#ifndef _RYML_SINGLE_HEADER_AMALGAMATED_HPP_
#define _RYML_SINGLE_HEADER_AMALGAMATED_HPP_

//
// Rapid YAML - a library to parse and emit YAML, and do it fast.
//
// https://github.com/biojppm/rapidyaml
//
// DO NOT EDIT. This file is generated automatically.
// This is an amalgamated single-header version of the library.
//
// INSTRUCTIONS:
//   - Include at will in any header of your project
//   - In one (and only one) of your project source files,
//     #define RYML_SINGLE_HDR_DEFINE_NOW and then include this header.
//     This will enable the function and class definitions in
//     the header file.
//   - To compile into a shared library, just define the
//     preprocessor symbol RYML_SHARED . This will take
//     care of symbol export/import.
//



//********************************************************************************
//--------------------------------------------------------------------------------
// LICENSE.txt
// https://github.com/biojppm/rapidyaml/LICENSE.txt
//--------------------------------------------------------------------------------
//********************************************************************************

// Copyright (c) 2018, Joao Paulo Magalhaes <dev@jpmag.me>
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//

 // shared library: export when defining
#if defined(RYML_SHARED) && defined(RYML_SINGLE_HDR_DEFINE_NOW) && !defined(RYML_EXPORTS)
#define RYML_EXPORTS
#endif


 // propagate defines to c4core
#if defined(RYML_SINGLE_HDR_DEFINE_NOW) && !defined(C4CORE_SINGLE_HDR_DEFINE_NOW)
#define C4CORE_SINGLE_HDR_DEFINE_NOW
#endif

#if defined(RYML_EXPORTS) && !defined(C4CORE_EXPORTS)
#define C4CORE_EXPORTS
#endif

#if defined(RYML_SHARED) && !defined(C4CORE_SHARED)
#define C4CORE_SHARED
#endif

// workaround for include removal while amalgamating
// resulting in <stdarg.h> missing in arm-none-eabi-g++
// https://github.com/biojppm/rapidyaml/issues/193
#include <stdarg.h>




//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/c4core_all.hpp
// https://github.com/biojppm/rapidyaml/src/c4/c4core_all.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4CORE_SINGLE_HEADER_AMALGAMATED_HPP_
#define _C4CORE_SINGLE_HEADER_AMALGAMATED_HPP_

//
// c4core - C++ utilities
//
// https://github.com/biojppm/c4core
//
// DO NOT EDIT. This file is generated automatically.
// This is an amalgamated single-header version of the library.
//
// INSTRUCTIONS:
//   - Include at will in any header of your project
//   - In one (and only one) of your project source files,
//     #define C4CORE_SINGLE_HDR_DEFINE_NOW and then include this header.
//     This will enable the function and class definitions in
//     the header file.
//   - To compile into a shared library, just define the
//     preprocessor symbol C4CORE_SHARED . This will take
//     care of symbol export/import.
//



//********************************************************************************
//--------------------------------------------------------------------------------
// LICENSE.txt
// https://github.com/biojppm/c4core/LICENSE.txt
//--------------------------------------------------------------------------------
//********************************************************************************

// Copyright (c) 2018, Joao Paulo Magalhaes <dev@jpmag.me>
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//

// shared library: export when defining
#if defined(C4CORE_SHARED) && defined(C4CORE_SINGLE_HDR_DEFINE_NOW) && !defined(C4CORE_EXPORTS)
#define C4CORE_EXPORTS
#endif




//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/export.hpp
// https://github.com/biojppm/c4core/src/c4/export.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef C4_EXPORT_HPP_
#define C4_EXPORT_HPP_

#ifdef _WIN32
    #ifdef C4CORE_SHARED
        #ifdef C4CORE_EXPORTS
            #define C4CORE_EXPORT __declspec(dllexport)
        #else
            #define C4CORE_EXPORT __declspec(dllimport)
        #endif
    #else
        #define C4CORE_EXPORT
    #endif
#else
    #define C4CORE_EXPORT
#endif

#endif /* C4CORE_EXPORT_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/export.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/preprocessor.hpp
// https://github.com/biojppm/c4core/src/c4/preprocessor.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_PREPROCESSOR_HPP_
#define _C4_PREPROCESSOR_HPP_

/** @file preprocessor.hpp Contains basic macros and preprocessor utilities.
 * @ingroup basic_headers */

#ifdef __clang__
    /* NOTE: using , ## __VA_ARGS__ to deal with zero-args calls to
     * variadic macros is not portable, but works in clang, gcc, msvc, icc.
     * clang requires switching off compiler warnings for pedantic mode.
     * @see http://stackoverflow.com/questions/32047685/variadic-macro-without-arguments */
#   pragma clang diagnostic push
#   pragma clang diagnostic ignored "-Wgnu-zero-variadic-macro-arguments" // warning: token pasting of ',' and __VA_ARGS__ is a GNU extension
#elif defined(__GNUC__)
    /* GCC also issues a warning for zero-args calls to variadic macros.
     * This warning is switched on with -pedantic and apparently there is no
     * easy way to turn it off as with clang. But marking this as a system
     * header works.
     * @see https://gcc.gnu.org/onlinedocs/cpp/System-Headers.html
     * @see http://stackoverflow.com/questions/35587137/ */
#   pragma GCC system_header
#endif

#define C4_WIDEN(str) L"" str

#define C4_COUNTOF(arr) (sizeof(arr)/sizeof((arr)[0]))

#define C4_EXPAND(arg) arg

/** useful in some macro calls with template arguments */
#define C4_COMMA ,
/** useful in some macro calls with template arguments
 * @see C4_COMMA */
#define C4_COMMA_X C4_COMMA

/** expand and quote */
#define C4_XQUOTE(arg) _C4_XQUOTE(arg)
#define _C4_XQUOTE(arg) C4_QUOTE(arg)
#define C4_QUOTE(arg) #arg

/** expand and concatenate */
#define C4_XCAT(arg1, arg2) _C4_XCAT(arg1, arg2)
#define _C4_XCAT(arg1, arg2) C4_CAT(arg1, arg2)
#define C4_CAT(arg1, arg2) arg1##arg2

#define C4_VERSION_CAT(major, minor, patch) ((major)*10000 + (minor)*100 + (patch))

/** A preprocessor foreach. Spectacular trick taken from:
 * http://stackoverflow.com/a/1872506/5875572
 * The first argument is for a macro receiving a single argument,
 * which will be called with every subsequent argument. There is
 * currently a limit of 32 arguments, and at least 1 must be provided.
 *
Example:
@code{.cpp}
struct Example {
    int a;
    int b;
    int c;
};
// define a one-arg macro to be called
#define PRN_STRUCT_OFFSETS(field) PRN_STRUCT_OFFSETS_(Example, field)
#define PRN_STRUCT_OFFSETS_(structure, field) printf(C4_XQUOTE(structure) ":" C4_XQUOTE(field)" - offset=%zu\n", offsetof(structure, field));

// now call the macro for a, b and c
C4_FOR_EACH(PRN_STRUCT_OFFSETS, a, b, c);
@endcode */
#define C4_FOR_EACH(what, ...) C4_FOR_EACH_SEP(what, ;, __VA_ARGS__)

/** same as C4_FOR_EACH(), but use a custom separator between statements.
 * If a comma is needed as the separator, use the C4_COMMA macro.
 * @see C4_FOR_EACH
 * @see C4_COMMA
 */
#define C4_FOR_EACH_SEP(what, sep, ...) _C4_FOR_EACH_(_C4_FOR_EACH_NARG(__VA_ARGS__), what, sep, __VA_ARGS__)

/// @cond dev

#define _C4_FOR_EACH_01(what, sep, x) what(x) sep
#define _C4_FOR_EACH_02(what, sep, x, ...) what(x) sep _C4_FOR_EACH_01(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_03(what, sep, x, ...) what(x) sep _C4_FOR_EACH_02(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_04(what, sep, x, ...) what(x) sep _C4_FOR_EACH_03(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_05(what, sep, x, ...) what(x) sep _C4_FOR_EACH_04(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_06(what, sep, x, ...) what(x) sep _C4_FOR_EACH_05(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_07(what, sep, x, ...) what(x) sep _C4_FOR_EACH_06(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_08(what, sep, x, ...) what(x) sep _C4_FOR_EACH_07(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_09(what, sep, x, ...) what(x) sep _C4_FOR_EACH_08(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_10(what, sep, x, ...) what(x) sep _C4_FOR_EACH_09(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_11(what, sep, x, ...) what(x) sep _C4_FOR_EACH_10(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_12(what, sep, x, ...) what(x) sep _C4_FOR_EACH_11(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_13(what, sep, x, ...) what(x) sep _C4_FOR_EACH_12(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_14(what, sep, x, ...) what(x) sep _C4_FOR_EACH_13(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_15(what, sep, x, ...) what(x) sep _C4_FOR_EACH_14(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_16(what, sep, x, ...) what(x) sep _C4_FOR_EACH_15(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_17(what, sep, x, ...) what(x) sep _C4_FOR_EACH_16(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_18(what, sep, x, ...) what(x) sep _C4_FOR_EACH_17(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_19(what, sep, x, ...) what(x) sep _C4_FOR_EACH_18(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_20(what, sep, x, ...) what(x) sep _C4_FOR_EACH_19(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_21(what, sep, x, ...) what(x) sep _C4_FOR_EACH_20(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_22(what, sep, x, ...) what(x) sep _C4_FOR_EACH_21(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_23(what, sep, x, ...) what(x) sep _C4_FOR_EACH_22(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_24(what, sep, x, ...) what(x) sep _C4_FOR_EACH_23(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_25(what, sep, x, ...) what(x) sep _C4_FOR_EACH_24(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_26(what, sep, x, ...) what(x) sep _C4_FOR_EACH_25(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_27(what, sep, x, ...) what(x) sep _C4_FOR_EACH_26(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_28(what, sep, x, ...) what(x) sep _C4_FOR_EACH_27(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_29(what, sep, x, ...) what(x) sep _C4_FOR_EACH_28(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_30(what, sep, x, ...) what(x) sep _C4_FOR_EACH_29(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_31(what, sep, x, ...) what(x) sep _C4_FOR_EACH_30(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_32(what, sep, x, ...) what(x) sep _C4_FOR_EACH_31(what, sep, __VA_ARGS__)
#define _C4_FOR_EACH_NARG(...) _C4_FOR_EACH_NARG_(__VA_ARGS__, _C4_FOR_EACH_RSEQ_N())
#define _C4_FOR_EACH_NARG_(...) _C4_FOR_EACH_ARG_N(__VA_ARGS__)
#define _C4_FOR_EACH_ARG_N(_01, _02, _03, _04, _05, _06, _07, _08, _09, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, N, ...) N
#define _C4_FOR_EACH_RSEQ_N() 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 09, 08, 07, 06, 05, 04, 03, 02, 01
#define _C4_FOR_EACH_(N, what, sep, ...) C4_XCAT(_C4_FOR_EACH_, N)(what, sep, __VA_ARGS__)

/// @endcond

#ifdef __clang__
#   pragma clang diagnostic pop
#endif

#endif /* _C4_PREPROCESSOR_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/preprocessor.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/platform.hpp
// https://github.com/biojppm/c4core/src/c4/platform.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_PLATFORM_HPP_
#define _C4_PLATFORM_HPP_

/** @file platform.hpp Provides platform information macros
 * @ingroup basic_headers */

// see also https://sourceforge.net/p/predef/wiki/OperatingSystems/

#if defined(_WIN64)
#   define C4_WIN
#   define C4_WIN64
#elif defined(_WIN32)
#   define C4_WIN
#   define C4_WIN32
#elif defined(__ANDROID__)
#   define C4_ANDROID
#elif defined(__APPLE__)
#   include "TargetConditionals.h"
#   if TARGET_OS_IPHONE || TARGET_IPHONE_SIMULATOR
#       define C4_IOS
#   elif TARGET_OS_MAC || TARGET_OS_OSX
#       define C4_MACOS
#   else
#       error "Unknown Apple platform"
#   endif
#elif defined(__linux__) || defined(__linux)
#   define C4_UNIX
#   define C4_LINUX
#elif defined(__unix__) || defined(__unix)
#   define C4_UNIX
#elif defined(__arm__) || defined(__aarch64__)
#   define C4_ARM
#elif defined(SWIG)
#   define C4_SWIG
#else
#   error "unknown platform"
#endif

#if defined(__posix) || defined(C4_UNIX) || defined(C4_LINUX)
#   define C4_POSIX
#endif


#endif /* _C4_PLATFORM_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/platform.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/cpu.hpp
// https://github.com/biojppm/c4core/src/c4/cpu.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_CPU_HPP_
#define _C4_CPU_HPP_

/** @file cpu.hpp Provides processor information macros
 * @ingroup basic_headers */

// see also https://sourceforge.net/p/predef/wiki/Architectures/
// see also https://sourceforge.net/p/predef/wiki/Endianness/
// see also https://github.com/googlesamples/android-ndk/blob/android-mk/hello-jni/jni/hello-jni.c
// see http://code.qt.io/cgit/qt/qtbase.git/tree/src/corelib/global/qprocessordetection.h

#ifdef __ORDER_LITTLE_ENDIAN__
    #define _C4EL __ORDER_LITTLE_ENDIAN__
#else
    #define _C4EL 1234
#endif

#ifdef __ORDER_BIG_ENDIAN__
    #define _C4EB __ORDER_BIG_ENDIAN__
#else
    #define _C4EB 4321
#endif

// mixed byte order (eg, PowerPC or ia64)
#define _C4EM 1111

#if defined(__x86_64) || defined(__x86_64__) || defined(__amd64) || defined(_M_X64)
    #define C4_CPU_X86_64
    #define C4_WORDSIZE 8
    #define C4_BYTE_ORDER _C4EL

#elif defined(__i386) || defined(__i386__) || defined(_M_IX86)
    #define C4_CPU_X86
    #define C4_WORDSIZE 4
    #define C4_BYTE_ORDER _C4EL

#elif defined(__arm__) || defined(_M_ARM) \
    || defined(__TARGET_ARCH_ARM) || defined(__aarch64__) || defined(_M_ARM64)
   #if defined(__aarch64__) || defined(_M_ARM64)
       #define C4_CPU_ARM64
       #define C4_CPU_ARMV8
       #define C4_WORDSIZE 8
   #else
       #define C4_CPU_ARM
       #define C4_WORDSIZE 4
       #if defined(__ARM_ARCH_8__) || defined(__ARM_ARCH_8A__)  \
        || (defined(__ARCH_ARM) && __ARCH_ARM >= 8)
        || (defined(__TARGET_ARCH_ARM) && __TARGET_ARCH_ARM >= 8)  \
           #define C4_CPU_ARMV8
       #elif defined(__ARM_ARCH_7__) || defined(_ARM_ARCH_7)    \
        || defined(__ARM_ARCH_7A__) || defined(__ARM_ARCH_7R__) \
        || defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7S__) \
        || defined(__ARM_ARCH_7EM__) \
        || (defined(__TARGET_ARCH_ARM) && __TARGET_ARCH_ARM >= 7) \
        || (defined(_M_ARM) && _M_ARM >= 7)
           #define C4_CPU_ARMV7
       #elif defined(__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) \
        || defined(__ARM_ARCH_6T2__) || defined(__ARM_ARCH_6Z__) \
        || defined(__ARM_ARCH_6K__)  || defined(__ARM_ARCH_6ZK__) \
        || defined(__ARM_ARCH_6M__) || defined(__ARM_ARCH_6KZ__) \
        || (defined(__TARGET_ARCH_ARM) && __TARGET_ARCH_ARM >= 6)
           #define C4_CPU_ARMV6
       #elif defined(__ARM_ARCH_5TEJ__) \
        || defined(__ARM_ARCH_5TE__) \
        || (defined(__TARGET_ARCH_ARM) && __TARGET_ARCH_ARM >= 5)
           #define C4_CPU_ARMV5
       #elif defined(__ARM_ARCH_4T__) \
        || (defined(__TARGET_ARCH_ARM) && __TARGET_ARCH_ARM >= 4)
           #define C4_CPU_ARMV4
       #else
           #error "unknown CPU architecture: ARM"
       #endif
   #endif
   #if defined(__ARMEL__) || defined(__LITTLE_ENDIAN__) || defined(__AARCH64EL__) \
       || (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)) \
       || defined(_MSC_VER) // winarm64 does not provide any of the above macros,
                            // but advises little-endianess:
                            // https://docs.microsoft.com/en-us/cpp/build/overview-of-arm-abi-conventions?view=msvc-170
                            // So if it is visual studio compiling, we'll assume little endian.
       #define C4_BYTE_ORDER _C4EL
   #elif defined(__ARMEB__) || defined(__BIG_ENDIAN__) || defined(__AARCH64EB__) \
       || (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
       #define C4_BYTE_ORDER _C4EB
   #elif defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_PDP_ENDIAN__)
       #define C4_BYTE_ORDER _C4EM
   #else
       #error "unknown endianness"
   #endif

#elif defined(__ia64) || defined(__ia64__) || defined(_M_IA64)
   #define C4_CPU_IA64
   #define C4_WORDSIZE 8
   #define C4_BYTE_ORDER _C4EM
   // itanium is bi-endian - check byte order below

#elif defined(__ppc__) || defined(__ppc) || defined(__powerpc__)       \
    || defined(_ARCH_COM) || defined(_ARCH_PWR) || defined(_ARCH_PPC)  \
    || defined(_M_MPPC) || defined(_M_PPC)
   #if defined(__ppc64__) || defined(__powerpc64__) || defined(__64BIT__)
       #define C4_CPU_PPC64
       #define C4_WORDSIZE 8
   #else
       #define C4_CPU_PPC
       #define C4_WORDSIZE 4
   #endif
   #define C4_BYTE_ORDER _C4EM
   // ppc is bi-endian - check byte order below

#elif defined(__s390x__) || defined(__zarch__) || defined(__SYSC_ZARCH_)
#   define C4_CPU_S390_X
#   define C4_WORDSIZE 8
#   define C4_BYTE_ORDER _C4EB

#elif defined(__riscv)
   #if __riscv_xlen == 64
       #define C4_CPU_RISCV64
       #define C4_WORDSIZE 8
   #else
       #define C4_CPU_RISCV32
       #define C4_WORDSIZE 4
   #endif
   #define C4_BYTE_ORDER _C4EL

#elif defined(__EMSCRIPTEN__)
#   define C4_BYTE_ORDER _C4EL
#   define C4_WORDSIZE 4

#elif defined(SWIG)
   #error "please define CPU architecture macros when compiling with swig"

#else
   #error "unknown CPU architecture"
#endif

#define C4_LITTLE_ENDIAN (C4_BYTE_ORDER == _C4EL)
#define C4_BIG_ENDIAN (C4_BYTE_ORDER == _C4EB)
#define C4_MIXED_ENDIAN (C4_BYTE_ORDER == _C4EM)

#endif /* _C4_CPU_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/cpu.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/compiler.hpp
// https://github.com/biojppm/c4core/src/c4/compiler.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_COMPILER_HPP_
#define _C4_COMPILER_HPP_

/** @file compiler.hpp Provides compiler information macros
 * @ingroup basic_headers */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/platform.hpp
//#include "c4/platform.hpp"
#if !defined(C4_PLATFORM_HPP_) && !defined(_C4_PLATFORM_HPP_)
#error "amalgamate: file c4/platform.hpp must have been included at this point"
#endif /* C4_PLATFORM_HPP_ */


// Compilers:
//      C4_MSVC
//             Visual Studio 2022: MSVC++ 17, 1930
//             Visual Studio 2019: MSVC++ 16, 1920
//             Visual Studio 2017: MSVC++ 15
//             Visual Studio 2015: MSVC++ 14
//             Visual Studio 2013: MSVC++ 13
//             Visual Studio 2013: MSVC++ 12
//             Visual Studio 2012: MSVC++ 11
//             Visual Studio 2010: MSVC++ 10
//             Visual Studio 2008: MSVC++ 09
//             Visual Studio 2005: MSVC++ 08
//      C4_CLANG
//      C4_GCC
//      C4_ICC (intel compiler)
/** @see http://sourceforge.net/p/predef/wiki/Compilers/ for a list of compiler identifier macros */
/** @see https://msdn.microsoft.com/en-us/library/b0084kay.aspx for VS2013 predefined macros */

#if defined(_MSC_VER)// && (defined(C4_WIN) || defined(C4_XBOX) || defined(C4_UE4))
#   define C4_MSVC
#   define C4_MSVC_VERSION_2022 17
#   define C4_MSVC_VERSION_2019 16
#   define C4_MSVC_VERSION_2017 15
#   define C4_MSVC_VERSION_2015 14
#   define C4_MSVC_VERSION_2013 12
#   define C4_MSVC_VERSION_2012 11
#   if _MSC_VER >= 1930
#       define C4_MSVC_VERSION C4_MSVC_VERSION_2022  // visual studio 2022
#       define C4_MSVC_2022
#   elif _MSC_VER >= 1920
#       define C4_MSVC_VERSION C_4MSVC_VERSION_2019  // visual studio 2019
#       define C4_MSVC_2019
#   elif _MSC_VER >= 1910
#       define C4_MSVC_VERSION C4_MSVC_VERSION_2017  // visual studio 2017
#       define C4_MSVC_2017
#   elif _MSC_VER == 1900
#       define C4_MSVC_VERSION C4_MSVC_VERSION_2015  // visual studio 2015
#       define C4_MSVC_2015
#   elif _MSC_VER == 1800
#       error "MSVC version not supported"
#       define C4_MSVC_VERSION C4_MSVC_VERSION_2013  // visual studio 2013
#       define C4_MSVC_2013
#   elif _MSC_VER == 1700
#       error "MSVC version not supported"
#       define C4_MSVC_VERSION C4_MSVC_VERSION_2012  // visual studio 2012
#       define C4_MSVC_2012
#   elif _MSC_VER == 1600
#       error "MSVC version not supported"
#       define C4_MSVC_VERSION 10  // visual studio 2010
#       define C4_MSVC_2010
#   elif _MSC_VER == 1500
#       error "MSVC version not supported"
#       define C4_MSVC_VERSION 09  // visual studio 2008
#       define C4_MSVC_2008
#   elif _MSC_VER == 1400
#       error "MSVC version not supported"
#       define C4_MSVC_VERSION 08  // visual studio 2005
#       define C4_MSVC_2005
#   else
#       error "MSVC version not supported"
#   endif // _MSC_VER
#else
#   define C4_MSVC_VERSION 0   // visual studio not present
#   define C4_GCC_LIKE
#   ifdef __INTEL_COMPILER // check ICC before checking GCC, as ICC defines __GNUC__ too
#       define C4_ICC
#       define C4_ICC_VERSION __INTEL_COMPILER
#   elif defined(__APPLE_CC__)
#       define C4_XCODE
#       if defined(__clang__)
#           define C4_CLANG
#           ifndef __apple_build_version__
#               define C4_CLANG_VERSION C4_VERSION_ENCODED(__clang_major__, __clang_minor__, __clang_patchlevel__)
#           else
#               define C4_CLANG_VERSION __apple_build_version__
#           endif
#       else
#           define C4_XCODE_VERSION __APPLE_CC__
#       endif
#   elif defined(__clang__)
#       define C4_CLANG
#       ifndef __apple_build_version__
#           define C4_CLANG_VERSION C4_VERSION_ENCODED(__clang_major__, __clang_minor__, __clang_patchlevel__)
#       else
#           define C4_CLANG_VERSION __apple_build_version__
#       endif
#   elif defined(__GNUC__)
#       define C4_GCC
#       if defined(__GNUC_PATCHLEVEL__)
#           define C4_GCC_VERSION C4_VERSION_ENCODED(__GNUC__, __GNUC_MINOR__, __GNUC_PATCHLEVEL__)
#       else
#           define C4_GCC_VERSION C4_VERSION_ENCODED(__GNUC__, __GNUC_MINOR__, 0)
#       endif
#       if __GNUC__ < 5
#           if __GNUC__ == 4 && __GNUC_MINOR__ >= 8
// provided by cmake sub-project
// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/gcc-4.8.hpp
//#               include "c4/gcc-4.8.hpp"
#if !defined(C4_GCC_4_8_HPP_) && !defined(_C4_GCC_4_8_HPP_)
#error "amalgamate: file c4/gcc-4.8.hpp must have been included at this point"
#endif /* C4_GCC_4_8_HPP_ */

#           else
// we do not support GCC < 4.8:
//  * misses std::is_trivially_copyable
//  * misses std::align
//  * -Wshadow has false positives when a local function parameter has the same name as a method
#               error "GCC < 4.8 is not supported"
#           endif
#       endif
#   endif
#endif // defined(C4_WIN) && defined(_MSC_VER)

#endif /* _C4_COMPILER_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/compiler.hpp)

// these includes are needed to work around conditional
// includes in the gcc4.8 shim
#include <cstdint>
#include <type_traits>
#include <cstring>




//********************************************************************************
//--------------------------------------------------------------------------------
// cmake/compat/c4/gcc-4.8.hpp
// https://github.com/biojppm/c4core/cmake/compat/c4/gcc-4.8.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_COMPAT_GCC_4_8_HPP_
#define _C4_COMPAT_GCC_4_8_HPP_

#if __GNUC__ == 4 && __GNUC_MINOR__ >= 8
/* STL polyfills for old GNU compilers */

_Pragma("GCC diagnostic ignored \"-Wshadow\"")
_Pragma("GCC diagnostic ignored \"-Wmissing-field-initializers\"")

#if __cplusplus
//included above:
//#include <cstdint>
//included above:
//#include <type_traits>

namespace std {

template<typename _Tp>
struct is_trivially_copyable : public integral_constant<bool,
    is_destructible<_Tp>::value && __has_trivial_destructor(_Tp) &&
    (__has_trivial_constructor(_Tp) || __has_trivial_copy(_Tp) || __has_trivial_assign(_Tp))>
{ };

template<typename _Tp>
using is_trivially_copy_constructible = has_trivial_copy_constructor<_Tp>;

template<typename _Tp>
using is_trivially_default_constructible = has_trivial_default_constructor<_Tp>;

template<typename _Tp>
using is_trivially_copy_assignable = has_trivial_copy_assign<_Tp>;

/* not supported */
template<typename _Tp>
struct is_trivially_move_constructible : false_type
{ };

/* not supported */
template<typename _Tp>
struct is_trivially_move_assignable : false_type
{ };

inline void *align(size_t __align, size_t __size, void*& __ptr, size_t& __space) noexcept
{
    if (__space < __size)
        return nullptr;
    const auto __intptr = reinterpret_cast<uintptr_t>(__ptr);
    const auto __aligned = (__intptr - 1u + __align) & -__align;
    const auto __diff = __aligned - __intptr;
    if (__diff > (__space - __size))
        return nullptr;
    else
    {
        __space -= __diff;
        return __ptr = reinterpret_cast<void*>(__aligned);
    }
}
typedef long double max_align_t ;

}
#else // __cplusplus

//included above:
//#include <string.h>
// see https://sourceware.org/bugzilla/show_bug.cgi?id=25399 (ubuntu gcc-4.8)
#define memset(s, c, count) __builtin_memset(s, c, count)

#endif // __cplusplus

#endif // __GNUC__ == 4 && __GNUC_MINOR__ >= 8

#endif // _C4_COMPAT_GCC_4_8_HPP_


// (end https://github.com/biojppm/c4core/cmake/compat/c4/gcc-4.8.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/language.hpp
// https://github.com/biojppm/c4core/src/c4/language.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_LANGUAGE_HPP_
#define _C4_LANGUAGE_HPP_

/** @file language.hpp Provides language standard information macros and
 * compiler agnostic utility macros: namespace facilities, function attributes,
 * variable attributes, etc.
 * @ingroup basic_headers */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/preprocessor.hpp
//#include "c4/preprocessor.hpp"
#if !defined(C4_PREPROCESSOR_HPP_) && !defined(_C4_PREPROCESSOR_HPP_)
#error "amalgamate: file c4/preprocessor.hpp must have been included at this point"
#endif /* C4_PREPROCESSOR_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/compiler.hpp
//#include "c4/compiler.hpp"
#if !defined(C4_COMPILER_HPP_) && !defined(_C4_COMPILER_HPP_)
#error "amalgamate: file c4/compiler.hpp must have been included at this point"
#endif /* C4_COMPILER_HPP_ */


/* Detect C++ standard.
 * @see http://stackoverflow.com/a/7132549/5875572 */
#ifndef C4_CPP
#   ifdef _MSC_VER
#       if _MSC_VER >= 1910  // >VS2015: VS2017, VS2019
#           if (!defined(_MSVC_LANG))
#               error _MSVC not defined
#           endif
#           if _MSVC_LANG >= 201705L
#               define C4_CPP 20
#               define C4_CPP20
#           elif _MSVC_LANG == 201703L
#               define C4_CPP 17
#               define C4_CPP17
#           elif _MSVC_LANG >= 201402L
#               define C4_CPP 14
#               define C4_CPP14
#           elif _MSVC_LANG >= 201103L
#               define C4_CPP 11
#               define C4_CPP11
#           else
#               error C++ lesser than C++11 not supported
#           endif
#       else
#           if _MSC_VER == 1900
#               define C4_CPP 14  // VS2015 is c++14 https://devblogs.microsoft.com/cppblog/c111417-features-in-vs-2015-rtm/
#               define C4_CPP14
#           elif _MSC_VER == 1800 // VS2013
#               define C4_CPP 11
#               define C4_CPP11
#           else
#               error C++ lesser than C++11 not supported
#           endif
#       endif
#   elif defined(__INTEL_COMPILER) // https://software.intel.com/en-us/node/524490
#       ifdef __INTEL_CXX20_MODE__ // not sure about this
#           define C4_CPP 20
#           define C4_CPP20
#       elif defined __INTEL_CXX17_MODE__ // not sure about this
#           define C4_CPP 17
#           define C4_CPP17
#       elif defined __INTEL_CXX14_MODE__ // not sure about this
#           define C4_CPP 14
#           define C4_CPP14
#       elif defined __INTEL_CXX11_MODE__
#           define C4_CPP 11
#           define C4_CPP11
#       else
#           error C++ lesser than C++11 not supported
#       endif
#   else
#       ifndef __cplusplus
#           error __cplusplus is not defined?
#       endif
#       if __cplusplus == 1
#           error cannot handle __cplusplus==1
#       elif __cplusplus >= 201709L
#           define C4_CPP 20
#           define C4_CPP20
#       elif __cplusplus >= 201703L
#           define C4_CPP 17
#           define C4_CPP17
#       elif __cplusplus >= 201402L
#           define C4_CPP 14
#           define C4_CPP14
#       elif __cplusplus >= 201103L
#           define C4_CPP 11
#           define C4_CPP11
#       elif __cplusplus >= 199711L
#           error C++ lesser than C++11 not supported
#       endif
#   endif
#else
#   ifdef C4_CPP == 20
#       define C4_CPP20
#   elif C4_CPP == 17
#       define C4_CPP17
#   elif C4_CPP == 14
#       define C4_CPP14
#   elif C4_CPP == 11
#       define C4_CPP11
#   elif C4_CPP == 98
#       define C4_CPP98
#       error C++ lesser than C++11 not supported
#   else
#       error C4_CPP must be one of 20, 17, 14, 11, 98
#   endif
#endif

#ifdef C4_CPP20
#   define C4_CPP17
#   define C4_CPP14
#   define C4_CPP11
#elif defined(C4_CPP17)
#   define C4_CPP14
#   define C4_CPP11
#elif defined(C4_CPP14)
#   define C4_CPP11
#endif

/** lifted from this answer: http://stackoverflow.com/a/20170989/5875572 */
#ifndef _MSC_VER
#  if __cplusplus < 201103
#    define C4_CONSTEXPR11
#    define C4_CONSTEXPR14
//#    define C4_NOEXCEPT
#  elif __cplusplus == 201103
#    define C4_CONSTEXPR11 constexpr
#    define C4_CONSTEXPR14
//#    define C4_NOEXCEPT noexcept
#  else
#    define C4_CONSTEXPR11 constexpr
#    define C4_CONSTEXPR14 constexpr
//#    define C4_NOEXCEPT noexcept
#  endif
#else  // _MSC_VER
#  if _MSC_VER < 1900
#    define C4_CONSTEXPR11
#    define C4_CONSTEXPR14
//#    define C4_NOEXCEPT
#  elif _MSC_VER < 2000
#    define C4_CONSTEXPR11 constexpr
#    define C4_CONSTEXPR14
//#    define C4_NOEXCEPT noexcept
#  else
#    define C4_CONSTEXPR11 constexpr
#    define C4_CONSTEXPR14 constexpr
//#    define C4_NOEXCEPT noexcept
#  endif
#endif  // _MSC_VER


#if C4_CPP < 17
#define C4_IF_CONSTEXPR
#define C4_INLINE_CONSTEXPR constexpr
#else
#define C4_IF_CONSTEXPR constexpr
#define C4_INLINE_CONSTEXPR inline constexpr
#endif


//------------------------------------------------------------

#define _C4_BEGIN_NAMESPACE(ns) namespace ns {
#define _C4_END_NAMESPACE(ns)   }

// MSVC cant handle the C4_FOR_EACH macro... need to fix this
//#define C4_BEGIN_NAMESPACE(...) C4_FOR_EACH_SEP(_C4_BEGIN_NAMESPACE, , __VA_ARGS__)
//#define C4_END_NAMESPACE(...) C4_FOR_EACH_SEP(_C4_END_NAMESPACE, , __VA_ARGS__)
#define C4_BEGIN_NAMESPACE(ns) namespace ns {
#define C4_END_NAMESPACE(ns) }

#define C4_BEGIN_HIDDEN_NAMESPACE namespace /*hidden*/ {
#define C4_END_HIDDEN_NAMESPACE } /* namespace hidden */

//------------------------------------------------------------

#ifndef C4_API
#   if defined(_MSC_VER)
#       if defined(C4_EXPORT)
#           define C4_API __declspec(dllexport)
#       elif defined(C4_IMPORT)
#           define C4_API __declspec(dllimport)
#       else
#           define C4_API
#       endif
#   else
#       define C4_API
#   endif
#endif

#ifndef _MSC_VER  ///< @todo assuming gcc-like compiler. check it is actually so.
/** for function attributes in GCC,
 * @see https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#Common-Function-Attributes */
/** for __builtin functions in GCC,
 * @see https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html */
#   define C4_RESTRICT __restrict__
#   define C4_RESTRICT_FN __attribute__((restrict))
#   define C4_NO_INLINE __attribute__((noinline))
#   define C4_ALWAYS_INLINE inline __attribute__((always_inline))
#   define C4_CONST __attribute__((const))
#   define C4_PURE __attribute__((pure))
/** force inlining of every callee function */
#   define C4_FLATTEN __atribute__((flatten))
/** mark a function as hot, ie as having a visible impact in CPU time
 * thus making it more likely to inline, etc
 * @see http://stackoverflow.com/questions/15028990/semantics-of-gcc-hot-attribute */
#   define C4_HOT __attribute__((hot))
/** mark a function as cold, ie as NOT having a visible impact in CPU time
 * @see http://stackoverflow.com/questions/15028990/semantics-of-gcc-hot-attribute */
#   define C4_COLD __attribute__((cold))
#   define C4_EXPECT(x, y) __builtin_expect(x, y) ///< @see https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html
#   define C4_LIKELY(x)   __builtin_expect(x, 1)
#   define C4_UNLIKELY(x) __builtin_expect(x, 0)
#   define C4_UNREACHABLE() __builtin_unreachable()
#   define C4_ATTR_FORMAT(...) //__attribute__((format (__VA_ARGS__))) ///< @see https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#Common-Function-Attributes
#   define C4_NORETURN __attribute__((noreturn))
#else
#   define C4_RESTRICT __restrict
#   define C4_RESTRICT_FN __declspec(restrict)
#   define C4_NO_INLINE __declspec(noinline)
#   define C4_ALWAYS_INLINE inline __forceinline
/** these are not available in VS AFAIK */
#   define C4_CONST
#   define C4_PURE
#   define C4_FLATTEN
#   define C4_HOT         /** @todo */
#   define C4_COLD        /** @todo */
#   define C4_EXPECT(x, y) x /** @todo */
#   define C4_LIKELY(x)   x /** @todo */
#   define C4_UNLIKELY(x) x /** @todo */
#   define C4_UNREACHABLE() /** @todo */
#   define C4_ATTR_FORMAT(...) /** */
#   define C4_NORETURN /** @todo */
#endif

#ifndef _MSC_VER
#   define C4_FUNC __FUNCTION__
#   define C4_PRETTY_FUNC __PRETTY_FUNCTION__
#else /// @todo assuming gcc-like compiler. check it is actually so.
#   define C4_FUNC __FUNCTION__
#   define C4_PRETTY_FUNC __FUNCSIG__
#endif

/** prevent compiler warnings about a specific var being unused */
#define C4_UNUSED(var) (void)var

#if C4_CPP >= 17
#define C4_STATIC_ASSERT(cond) static_assert(cond)
#else
#define C4_STATIC_ASSERT(cond) static_assert((cond), #cond)
#endif
#define C4_STATIC_ASSERT_MSG(cond, msg) static_assert((cond), #cond ": " msg)

/** @def C4_DONT_OPTIMIZE idea lifted from GoogleBenchmark.
 * @see https://github.com/google/benchmark/blob/master/include/benchmark/benchmark_api.h */
namespace c4 {
namespace detail {
#ifdef __GNUC__
#   define C4_DONT_OPTIMIZE(var) c4::detail::dont_optimize(var)
template< class T >
C4_ALWAYS_INLINE void dont_optimize(T const& value) { asm volatile("" : : "g"(value) : "memory"); }
#else
#   define C4_DONT_OPTIMIZE(var) c4::detail::use_char_pointer(reinterpret_cast< const char* >(&var))
void use_char_pointer(char const volatile*);
#endif
} // namespace detail
} // namespace c4

/** @def C4_KEEP_EMPTY_LOOP prevent an empty loop from being optimized out.
 * @see http://stackoverflow.com/a/7084193/5875572 */
#ifndef _MSC_VER
#   define C4_KEEP_EMPTY_LOOP { asm(""); }
#else
#   define C4_KEEP_EMPTY_LOOP { char c; C4_DONT_OPTIMIZE(c); }
#endif

/** @def C4_VA_LIST_REUSE_MUST_COPY
 * @todo <jpmag> I strongly suspect that this is actually only in UNIX platforms. revisit this. */
#ifdef __GNUC__
#   define C4_VA_LIST_REUSE_MUST_COPY
#endif

#endif /* _C4_LANGUAGE_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/language.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/types.hpp
// https://github.com/biojppm/c4core/src/c4/types.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_TYPES_HPP_
#define _C4_TYPES_HPP_

//included above:
//#include <stdint.h>
#include <stddef.h>
//included above:
//#include <type_traits>

#if __cplusplus >= 201103L
#include <utility>  // for integer_sequence and friends
#endif

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/preprocessor.hpp
//#include "c4/preprocessor.hpp"
#if !defined(C4_PREPROCESSOR_HPP_) && !defined(_C4_PREPROCESSOR_HPP_)
#error "amalgamate: file c4/preprocessor.hpp must have been included at this point"
#endif /* C4_PREPROCESSOR_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/language.hpp
//#include "c4/language.hpp"
#if !defined(C4_LANGUAGE_HPP_) && !defined(_C4_LANGUAGE_HPP_)
#error "amalgamate: file c4/language.hpp must have been included at this point"
#endif /* C4_LANGUAGE_HPP_ */


/** @file types.hpp basic types, and utility macros and traits for types.
 * @ingroup basic_headers */

/** @defgroup types Type utilities */

namespace c4 {

/** @defgroup intrinsic_types Intrinsic types
 * @ingroup types
 * @{ */

using cbyte = const char; /**< a constant byte */
using  byte =       char; /**< a mutable byte */

using  i8 =   int8_t;
using i16 =  int16_t;
using i32 =  int32_t;
using i64 =  int64_t;
using  u8 =  uint8_t;
using u16 = uint16_t;
using u32 = uint32_t;
using u64 = uint64_t;

using f32 =  float;
using f64 = double;

using ssize_t = typename std::make_signed<size_t>::type;

/** @} */

//--------------------------------------------------

/** @defgroup utility_types Utility types
 * @ingroup types
 * @{ */

// some tag types

/** a tag type for initializing the containers with variadic arguments a la
 * initializer_list, minus the initializer_list overload problems.
 */
struct aggregate_t {};
/** @see aggregate_t */
constexpr const aggregate_t aggregate{};

/** a tag type for specifying the initial capacity of allocatable contiguous storage */
struct with_capacity_t {};
/** @see with_capacity_t */
constexpr const with_capacity_t with_capacity{};

/** a tag type for disambiguating template parameter packs in variadic template overloads */
struct varargs_t {};
/** @see with_capacity_t */
constexpr const varargs_t varargs{};


//--------------------------------------------------

/** whether a value should be used in place of a const-reference in argument passing. */
template<class T>
struct cref_uses_val
{
    enum { value = (
    std::is_scalar<T>::value
    ||
    (
#if C4_CPP >= 20
        (std::is_trivially_copyable<T>::value && std::is_standard_layout<T>::value)
#else
        std::is_pod<T>::value
#endif
        &&
        sizeof(T) <= sizeof(size_t))) };
};
/** utility macro to override the default behaviour for c4::fastcref<T>
 @see fastcref */
#define C4_CREF_USES_VAL(T) \
template<>                  \
struct cref_uses_val<T>     \
{                           \
    enum { value = true };  \
};

/** Whether to use pass-by-value or pass-by-const-reference in a function argument
 * or return type. */
template<class T>
using fastcref = typename std::conditional<c4::cref_uses_val<T>::value, T, T const&>::type;

//--------------------------------------------------

/** Just what its name says. Useful sometimes as a default empty policy class. */
struct EmptyStruct
{
    template<class... T> EmptyStruct(T && ...){}
};

/** Just what its name says. Useful sometimes as a default policy class to
 * be inherited from. */
struct EmptyStructVirtual
{
    virtual ~EmptyStructVirtual() = default;
    template<class... T> EmptyStructVirtual(T && ...){}
};


/** */
template<class T>
struct inheritfrom : public T {};

//--------------------------------------------------
// Utilities to make a class obey size restrictions (eg, min size or size multiple of).
// DirectX usually makes this restriction with uniform buffers.
// This is also useful for padding to prevent false-sharing.

/** how many bytes must be added to size such that the result is at least minsize? */
C4_ALWAYS_INLINE constexpr size_t min_remainder(size_t size, size_t minsize) noexcept
{
    return size < minsize ? minsize-size : 0;
}

/** how many bytes must be added to size such that the result is a multiple of multipleof?  */
C4_ALWAYS_INLINE constexpr size_t mult_remainder(size_t size, size_t multipleof) noexcept
{
    return (((size % multipleof) != 0) ? (multipleof-(size % multipleof)) : 0);
}

/* force the following class to be tightly packed. */
#pragma pack(push, 1)
/** pad a class with more bytes at the end.
 * @see http://stackoverflow.com/questions/21092415/force-c-structure-to-pack-tightly */
template<class T, size_t BytesToPadAtEnd>
struct Padded : public T
{
    using T::T;
    using T::operator=;
    Padded(T const& val) : T(val) {}
    Padded(T && val) : T(val) {}
    char ___c4padspace___[BytesToPadAtEnd];
};
#pragma pack(pop)
/** When the padding argument is 0, we cannot declare the char[] array. */
template<class T>
struct Padded<T, 0> : public T
{
    using T::T;
    using T::operator=;
    Padded(T const& val) : T(val) {}
    Padded(T && val) : T(val) {}
};

/** make T have a size which is at least Min bytes */
template<class T, size_t Min>
using MinSized = Padded<T, min_remainder(sizeof(T), Min)>;

/** make T have a size which is a multiple of Mult bytes */
template<class T, size_t Mult>
using MultSized = Padded<T, mult_remainder(sizeof(T), Mult)>;

/** make T have a size which is simultaneously:
 *  -bigger or equal than Min
 *  -a multiple of Mult */
template<class T, size_t Min, size_t Mult>
using MinMultSized = MultSized<MinSized<T, Min>, Mult>;

/** make T be suitable for use as a uniform buffer. (at least with DirectX). */
template<class T>
using UbufSized = MinMultSized<T, 64, 16>;


//-----------------------------------------------------------------------------

#define C4_NO_COPY_CTOR(ty) ty(ty const&) = delete
#define C4_NO_MOVE_CTOR(ty) ty(ty     &&) = delete
#define C4_NO_COPY_ASSIGN(ty) ty& operator=(ty const&) = delete
#define C4_NO_MOVE_ASSIGN(ty) ty& operator=(ty     &&) = delete
#define C4_DEFAULT_COPY_CTOR(ty) ty(ty const&) noexcept = default
#define C4_DEFAULT_MOVE_CTOR(ty) ty(ty     &&) noexcept = default
#define C4_DEFAULT_COPY_ASSIGN(ty) ty& operator=(ty const&) noexcept = default
#define C4_DEFAULT_MOVE_ASSIGN(ty) ty& operator=(ty     &&) noexcept = default

#define C4_NO_COPY_OR_MOVE_CTOR(ty) \
    C4_NO_COPY_CTOR(ty); \
    C4_NO_MOVE_CTOR(ty)

#define C4_NO_COPY_OR_MOVE_ASSIGN(ty) \
    C4_NO_COPY_ASSIGN(ty); \
    C4_NO_MOVE_ASSIGN(ty)

#define C4_NO_COPY_OR_MOVE(ty) \
    C4_NO_COPY_OR_MOVE_CTOR(ty); \
    C4_NO_COPY_OR_MOVE_ASSIGN(ty)

#define C4_DEFAULT_COPY_AND_MOVE_CTOR(ty) \
    C4_DEFAULT_COPY_CTOR(ty); \
    C4_DEFAULT_MOVE_CTOR(ty)

#define C4_DEFAULT_COPY_AND_MOVE_ASSIGN(ty) \
    C4_DEFAULT_COPY_ASSIGN(ty); \
    C4_DEFAULT_MOVE_ASSIGN(ty)

#define C4_DEFAULT_COPY_AND_MOVE(ty) \
    C4_DEFAULT_COPY_AND_MOVE_CTOR(ty); \
    C4_DEFAULT_COPY_AND_MOVE_ASSIGN(ty)

/** @see https://en.cppreference.com/w/cpp/named_req/TriviallyCopyable */
#define C4_MUST_BE_TRIVIAL_COPY(ty) \
    static_assert(std::is_trivially_copyable<ty>::value, #ty " must be trivially copyable")

/** @} */


//-----------------------------------------------------------------------------

/** @defgroup traits_types Type traits utilities
 * @ingroup types
 * @{ */

// http://stackoverflow.com/questions/10821380/is-t-an-instance-of-a-template-in-c
template<template<typename...> class X, typename    T> struct is_instance_of_tpl             : std::false_type {};
template<template<typename...> class X, typename... Y> struct is_instance_of_tpl<X, X<Y...>> : std::true_type {};

//-----------------------------------------------------------------------------

/** SFINAE. use this macro to enable a template function overload
based on a compile-time condition.
@code
// define an overload for a non-pod type
template<class T, C4_REQUIRE_T(std::is_pod<T>::value)>
void foo() { std::cout << "pod type\n"; }

// define an overload for a non-pod type
template<class T, C4_REQUIRE_T(!std::is_pod<T>::value)>
void foo() { std::cout << "nonpod type\n"; }

struct non_pod
{
    non_pod() : name("asdfkjhasdkjh") {}
    const char *name;
};

int main()
{
    foo<float>(); // prints "pod type"
    foo<non_pod>(); // prints "nonpod type"
}
@endcode */
#define C4_REQUIRE_T(cond) typename std::enable_if<cond, bool>::type* = nullptr

/** enable_if for a return type
 * @see C4_REQUIRE_T */
#define C4_REQUIRE_R(cond, type_) typename std::enable_if<cond, type_>::type

//-----------------------------------------------------------------------------
/** define a traits class reporting whether a type provides a member typedef */
#define C4_DEFINE_HAS_TYPEDEF(member_typedef)               \
template<typename T>                                        \
struct has_##stype                                          \
{                                                           \
private:                                                    \
                                                            \
    typedef char                      yes;                  \
    typedef struct { char array[2]; } no;                   \
                                                            \
    template<typename C>                                    \
    static yes _test(typename C::member_typedef*);          \
                                                            \
    template<typename C>                                    \
    static no  _test(...);                                  \
                                                            \
public:                                                     \
                                                            \
    enum { value = (sizeof(_test<T>(0)) == sizeof(yes)) };  \
                                                            \
}


/** @} */


//-----------------------------------------------------------------------------


/** @defgroup type_declarations Type declaration utilities
 * @ingroup types
 * @{ */

#define _c4_DEFINE_ARRAY_TYPES_WITHOUT_ITERATOR(T, I)           \
                                                                \
    using size_type = I;                                        \
    using ssize_type = typename std::make_signed<I>::type;      \
    using difference_type = typename std::make_signed<I>::type; \
                                                                \
    using value_type = T;                                       \
    using pointer = T*;                                         \
    using const_pointer = T const*;                             \
    using reference = T&;                                       \
    using const_reference = T const&

#define _c4_DEFINE_TUPLE_ARRAY_TYPES_WITHOUT_ITERATOR(interior_types, I) \
                                                                        \
    using size_type = I;                                                \
    using ssize_type = typename std::make_signed<I>::type;              \
    using difference_type = typename std::make_signed<I>::type;         \
                                                                        \
    template<I n> using value_type = typename std::tuple_element< n, std::tuple<interior_types...>>::type; \
    template<I n> using pointer = value_type<n>*;                       \
    template<I n> using const_pointer = value_type<n> const*;           \
    template<I n> using reference = value_type<n>&;                     \
    template<I n> using const_reference = value_type<n> const&


#define _c4_DEFINE_ARRAY_TYPES(T, I)                                \
                                                                    \
    _c4_DEFINE_ARRAY_TYPES_WITHOUT_ITERATOR(T, I);                  \
                                                                    \
    using iterator = T*;                                            \
    using const_iterator = T const*;                                \
    using reverse_iterator = std::reverse_iterator<T*>;             \
    using const_reverse_iterator = std::reverse_iterator<T const*>


#define _c4_DEFINE_TUPLE_ARRAY_TYPES(interior_types, I)                 \
                                                                        \
    _c4_DEFINE_TUPLE_ARRAY_TYPES_WITHOUT_ITERATOR(interior_types, I);   \
                                                                        \
    template<I n> using iterator = value_type<n>*;                      \
    template<I n> using const_iterator = value_type<n> const*;          \
    template<I n> using reverse_iterator = std::reverse_iterator< value_type<n>*>; \
    template<I n> using const_reverse_iterator = std::reverse_iterator< value_type<n> const*>



/** @} */


//-----------------------------------------------------------------------------


/** @defgroup compatility_utilities Backport implementation of some Modern C++ utilities
 * @ingroup types
 * @{ */

//-----------------------------------------------------------------------------
// index_sequence and friends are available only for C++14 and later.
// A C++11 implementation is provided here.
// This implementation was copied over from clang.
// see http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/utility?revision=211563&view=markup#l687

#if __cplusplus > 201103L

using std::integer_sequence;
using std::index_sequence;
using std::make_integer_sequence;
using std::make_index_sequence;
using std::index_sequence_for;

#else

/** C++11 implementation of integer sequence
 * @see https://en.cppreference.com/w/cpp/utility/integer_sequence
 * @see taken from clang: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/utility?revision=211563&view=markup#l687 */
template<class _Tp, _Tp... _Ip>
struct integer_sequence
{
    static_assert(std::is_integral<_Tp>::value,
                  "std::integer_sequence can only be instantiated with an integral type" );
    using value_type = _Tp;
    static constexpr size_t size() noexcept { return sizeof...(_Ip); }
};

/** C++11 implementation of index sequence
 * @see https://en.cppreference.com/w/cpp/utility/integer_sequence
 * @see taken from clang: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/utility?revision=211563&view=markup#l687 */
template<size_t... _Ip>
using index_sequence = integer_sequence<size_t, _Ip...>;

/** @cond DONT_DOCUMENT_THIS */
namespace __detail {

template<typename _Tp, size_t ..._Extra>
struct __repeat;

template<typename _Tp, _Tp ..._Np, size_t ..._Extra>
struct __repeat<integer_sequence<_Tp, _Np...>, _Extra...>
{
    using type = integer_sequence<_Tp,
                            _Np...,
                            sizeof...(_Np) + _Np...,
                            2 * sizeof...(_Np) + _Np...,
                            3 * sizeof...(_Np) + _Np...,
                            4 * sizeof...(_Np) + _Np...,
                            5 * sizeof...(_Np) + _Np...,
                            6 * sizeof...(_Np) + _Np...,
                            7 * sizeof...(_Np) + _Np...,
                            _Extra...>;
};

template<size_t _Np> struct __parity;
template<size_t _Np> struct __make : __parity<_Np % 8>::template __pmake<_Np> {};

template<> struct __make<0> { using type = integer_sequence<size_t>; };
template<> struct __make<1> { using type = integer_sequence<size_t, 0>; };
template<> struct __make<2> { using type = integer_sequence<size_t, 0, 1>; };
template<> struct __make<3> { using type = integer_sequence<size_t, 0, 1, 2>; };
template<> struct __make<4> { using type = integer_sequence<size_t, 0, 1, 2, 3>; };
template<> struct __make<5> { using type = integer_sequence<size_t, 0, 1, 2, 3, 4>; };
template<> struct __make<6> { using type = integer_sequence<size_t, 0, 1, 2, 3, 4, 5>; };
template<> struct __make<7> { using type = integer_sequence<size_t, 0, 1, 2, 3, 4, 5, 6>; };

template<> struct __parity<0> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type> {}; };
template<> struct __parity<1> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 1> {}; };
template<> struct __parity<2> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 2, _Np - 1> {}; };
template<> struct __parity<3> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 3, _Np - 2, _Np - 1> {}; };
template<> struct __parity<4> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; };
template<> struct __parity<5> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 5, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; };
template<> struct __parity<6> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 6, _Np - 5, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; };
template<> struct __parity<7> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 7, _Np - 6, _Np - 5, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; };

template<typename _Tp, typename _Up>
struct __convert
{
    template<typename> struct __result;
    template<_Tp ..._Np> struct __result<integer_sequence<_Tp, _Np...>>
    {
        using type = integer_sequence<_Up, _Np...>;
    };
};

template<typename _Tp>
struct __convert<_Tp, _Tp>
{
    template<typename _Up> struct __result
    {
         using type = _Up;
    };
};

template<typename _Tp, _Tp _Np>
using __make_integer_sequence_unchecked = typename __detail::__convert<size_t, _Tp>::template __result<typename __detail::__make<_Np>::type>::type;

template<class _Tp, _Tp _Ep>
struct __make_integer_sequence
{
    static_assert(std::is_integral<_Tp>::value,
                  "std::make_integer_sequence can only be instantiated with an integral type" );
    static_assert(0 <= _Ep, "std::make_integer_sequence input shall not be negative");
    typedef __make_integer_sequence_unchecked<_Tp, _Ep> type;
};

} // namespace __detail
/** @endcond */


/** C++11 implementation of index sequence
 * @see https://en.cppreference.com/w/cpp/utility/integer_sequence
 * @see taken from clang: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/utility?revision=211563&view=markup#l687 */
template<class _Tp, _Tp _Np>
using make_integer_sequence = typename __detail::__make_integer_sequence<_Tp, _Np>::type;

/** C++11 implementation of index sequence
 * @see https://en.cppreference.com/w/cpp/utility/integer_sequence
 * @see taken from clang: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/utility?revision=211563&view=markup#l687 */
template<size_t _Np>
using make_index_sequence = make_integer_sequence<size_t, _Np>;

/** C++11 implementation of index sequence
 * @see https://en.cppreference.com/w/cpp/utility/integer_sequence
 * @see taken from clang: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/utility?revision=211563&view=markup#l687 */
template<class... _Tp>
using index_sequence_for = make_index_sequence<sizeof...(_Tp)>;
#endif

/** @} */


} // namespace c4

#endif /* _C4_TYPES_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/types.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/config.hpp
// https://github.com/biojppm/c4core/src/c4/config.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_CONFIG_HPP_
#define _C4_CONFIG_HPP_

/** @defgroup basic_headers Basic headers
 * @brief Headers providing basic macros, platform+cpu+compiler information,
 * C++ facilities and basic typedefs. */

/** @file config.hpp Contains configuration defines and includes the basic_headers.
 * @ingroup basic_headers */

//#define C4_DEBUG

#define C4_ERROR_SHOWS_FILELINE
//#define C4_ERROR_SHOWS_FUNC
//#define C4_ERROR_THROWS_EXCEPTION
//#define C4_NO_ALLOC_DEFAULTS
//#define C4_REDEFINE_CPPNEW

#ifndef C4_SIZE_TYPE
#   define C4_SIZE_TYPE size_t
#endif

#ifndef C4_STR_SIZE_TYPE
#   define C4_STR_SIZE_TYPE C4_SIZE_TYPE
#endif

#ifndef C4_TIME_TYPE
#   define C4_TIME_TYPE double
#endif

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/export.hpp
//#include "c4/export.hpp"
#if !defined(C4_EXPORT_HPP_) && !defined(_C4_EXPORT_HPP_)
#error "amalgamate: file c4/export.hpp must have been included at this point"
#endif /* C4_EXPORT_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/preprocessor.hpp
//#include "c4/preprocessor.hpp"
#if !defined(C4_PREPROCESSOR_HPP_) && !defined(_C4_PREPROCESSOR_HPP_)
#error "amalgamate: file c4/preprocessor.hpp must have been included at this point"
#endif /* C4_PREPROCESSOR_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/platform.hpp
//#include "c4/platform.hpp"
#if !defined(C4_PLATFORM_HPP_) && !defined(_C4_PLATFORM_HPP_)
#error "amalgamate: file c4/platform.hpp must have been included at this point"
#endif /* C4_PLATFORM_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/cpu.hpp
//#include "c4/cpu.hpp"
#if !defined(C4_CPU_HPP_) && !defined(_C4_CPU_HPP_)
#error "amalgamate: file c4/cpu.hpp must have been included at this point"
#endif /* C4_CPU_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/compiler.hpp
//#include "c4/compiler.hpp"
#if !defined(C4_COMPILER_HPP_) && !defined(_C4_COMPILER_HPP_)
#error "amalgamate: file c4/compiler.hpp must have been included at this point"
#endif /* C4_COMPILER_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/language.hpp
//#include "c4/language.hpp"
#if !defined(C4_LANGUAGE_HPP_) && !defined(_C4_LANGUAGE_HPP_)
#error "amalgamate: file c4/language.hpp must have been included at this point"
#endif /* C4_LANGUAGE_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/types.hpp
//#include "c4/types.hpp"
#if !defined(C4_TYPES_HPP_) && !defined(_C4_TYPES_HPP_)
#error "amalgamate: file c4/types.hpp must have been included at this point"
#endif /* C4_TYPES_HPP_ */


#endif // _C4_CONFIG_HPP_


// (end https://github.com/biojppm/c4core/src/c4/config.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/ext/debugbreak/debugbreak.h
// https://github.com/biojppm/c4core/src/c4/ext/debugbreak/debugbreak.h
//--------------------------------------------------------------------------------
//********************************************************************************

/* Copyright (c) 2011-2021, Scott Tsai
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
#ifndef DEBUG_BREAK_H
#define DEBUG_BREAK_H

#ifdef _MSC_VER

#define debug_break __debugbreak

#else

#ifdef __cplusplus
extern "C" {
#endif

#define DEBUG_BREAK_USE_TRAP_INSTRUCTION 1
#define DEBUG_BREAK_USE_BULTIN_TRAP      2
#define DEBUG_BREAK_USE_SIGTRAP          3

#if defined(__i386__) || defined(__x86_64__)
	#define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_TRAP_INSTRUCTION
__inline__ static void trap_instruction(void)
{
	__asm__ volatile("int $0x03");
}
#elif defined(__thumb__)
	#define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_TRAP_INSTRUCTION
/* FIXME: handle __THUMB_INTERWORK__ */
__attribute__((always_inline))
__inline__ static void trap_instruction(void)
{
	/* See 'arm-linux-tdep.c' in GDB source.
	 * Both instruction sequences below work. */
#if 1
	/* 'eabi_linux_thumb_le_breakpoint' */
	__asm__ volatile(".inst 0xde01");
#else
	/* 'eabi_linux_thumb2_le_breakpoint' */
	__asm__ volatile(".inst.w 0xf7f0a000");
#endif

	/* Known problem:
	 * After a breakpoint hit, can't 'stepi', 'step', or 'continue' in GDB.
	 * 'step' would keep getting stuck on the same instruction.
	 *
	 * Workaround: use the new GDB commands 'debugbreak-step' and
	 * 'debugbreak-continue' that become available
	 * after you source the script from GDB:
	 *
	 * $ gdb -x debugbreak-gdb.py <... USUAL ARGUMENTS ...>
	 *
	 * 'debugbreak-step' would jump over the breakpoint instruction with
	 * roughly equivalent of:
	 * (gdb) set $instruction_len = 2
	 * (gdb) tbreak *($pc + $instruction_len)
	 * (gdb) jump   *($pc + $instruction_len)
	 */
}
#elif defined(__arm__) && !defined(__thumb__)
	#define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_TRAP_INSTRUCTION
__attribute__((always_inline))
__inline__ static void trap_instruction(void)
{
	/* See 'arm-linux-tdep.c' in GDB source,
	 * 'eabi_linux_arm_le_breakpoint' */
	__asm__ volatile(".inst 0xe7f001f0");
	/* Known problem:
	 * Same problem and workaround as Thumb mode */
}
#elif defined(__aarch64__) && defined(__APPLE__)
	#define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_BULTIN_DEBUGTRAP
#elif defined(__aarch64__)
	#define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_TRAP_INSTRUCTION
__attribute__((always_inline))
__inline__ static void trap_instruction(void)
{
	/* See 'aarch64-tdep.c' in GDB source,
	 * 'aarch64_default_breakpoint' */
	__asm__ volatile(".inst 0xd4200000");
}
#elif defined(__powerpc__)
	/* PPC 32 or 64-bit, big or little endian */
	#define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_TRAP_INSTRUCTION
__attribute__((always_inline))
__inline__ static void trap_instruction(void)
{
	/* See 'rs6000-tdep.c' in GDB source,
	 * 'rs6000_breakpoint' */
	__asm__ volatile(".4byte 0x7d821008");

	/* Known problem:
	 * After a breakpoint hit, can't 'stepi', 'step', or 'continue' in GDB.
	 * 'step' stuck on the same instruction ("twge r2,r2").
	 *
	 * The workaround is the same as ARM Thumb mode: use debugbreak-gdb.py
	 * or manually jump over the instruction. */
}
#elif defined(__riscv)
	/* RISC-V 32 or 64-bit, whether the "C" extension
	 * for compressed, 16-bit instructions are supported or not */
	#define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_TRAP_INSTRUCTION
__attribute__((always_inline))
__inline__ static void trap_instruction(void)
{
	/* See 'riscv-tdep.c' in GDB source,
	 * 'riscv_sw_breakpoint_from_kind' */
	__asm__ volatile(".4byte 0x00100073");
}
#else
	#define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_SIGTRAP
#endif


#ifndef DEBUG_BREAK_IMPL
#error "debugbreak.h is not supported on this target"
#elif DEBUG_BREAK_IMPL == DEBUG_BREAK_USE_TRAP_INSTRUCTION
__attribute__((always_inline))
__inline__ static void debug_break(void)
{
	trap_instruction();
}
#elif DEBUG_BREAK_IMPL == DEBUG_BREAK_USE_BULTIN_DEBUGTRAP
__attribute__((always_inline))
__inline__ static void debug_break(void)
{
	__builtin_debugtrap();
}
#elif DEBUG_BREAK_IMPL == DEBUG_BREAK_USE_BULTIN_TRAP
__attribute__((always_inline))
__inline__ static void debug_break(void)
{
	__builtin_trap();
}
#elif DEBUG_BREAK_IMPL == DEBUG_BREAK_USE_SIGTRAP
#include <signal.h>
__attribute__((always_inline))
__inline__ static void debug_break(void)
{
	raise(SIGTRAP);
}
#else
#error "invalid DEBUG_BREAK_IMPL value"
#endif

#ifdef __cplusplus
}
#endif

#endif /* ifdef _MSC_VER */

#endif /* ifndef DEBUG_BREAK_H */


// (end https://github.com/biojppm/c4core/src/c4/ext/debugbreak/debugbreak.h)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/error.hpp
// https://github.com/biojppm/c4core/src/c4/error.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_ERROR_HPP_
#define _C4_ERROR_HPP_

/** @file error.hpp Facilities for error reporting and runtime assertions. */

/** @defgroup error_checking Error checking */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/config.hpp
//#include "c4/config.hpp"
#if !defined(C4_CONFIG_HPP_) && !defined(_C4_CONFIG_HPP_)
#error "amalgamate: file c4/config.hpp must have been included at this point"
#endif /* C4_CONFIG_HPP_ */


#ifdef _DOXYGEN_
    /** if this is defined and exceptions are enabled, then calls to C4_ERROR()
     * will throw an exception
     * @ingroup error_checking */
#   define C4_EXCEPTIONS_ENABLED
    /** if this is defined and exceptions are enabled, then calls to C4_ERROR()
     *  will throw an exception
     * @see C4_EXCEPTIONS_ENABLED
     * @ingroup error_checking */
#   define C4_ERROR_THROWS_EXCEPTION
    /** evaluates to noexcept when C4_ERROR might be called and
     * exceptions are disabled. Otherwise, defaults to nothing.
     * @ingroup error_checking */
#   define C4_NOEXCEPT
#endif // _DOXYGEN_

#if defined(C4_EXCEPTIONS_ENABLED) && defined(C4_ERROR_THROWS_EXCEPTION)
#   define C4_NOEXCEPT
#else
#   define C4_NOEXCEPT noexcept
#endif


namespace c4 {
namespace detail {
struct fail_type__ {};
} // detail
} // c4
#define C4_STATIC_ERROR(dummy_type, errmsg)                             \
    static_assert(std::is_same<dummy_type, c4::detail::fail_type__>::value, errmsg)


//-----------------------------------------------------------------------------

#define C4_ASSERT_SAME_TYPE(ty1, ty2)                       \
    C4_STATIC_ASSERT(std::is_same<ty1 C4_COMMA_X ty2>::value)

#define C4_ASSERT_DIFF_TYPE(ty1, ty2)                       \
    C4_STATIC_ASSERT( ! std::is_same<ty1 C4_COMMA_X ty2>::value)


//-----------------------------------------------------------------------------

#ifdef _DOXYGEN_
/** utility macro that triggers a breakpoint when
 * the debugger is attached and NDEBUG is not defined.
 * @ingroup error_checking */
#   define C4_DEBUG_BREAK()
#endif // _DOXYGEN_


#if defined(NDEBUG) || defined(C4_NO_DEBUG_BREAK)
#   define C4_DEBUG_BREAK()
#else
#   ifdef __clang__
#       pragma clang diagnostic push
#       if !defined(__APPLE_CC__)
#           if __clang_major__ >= 10
#               pragma clang diagnostic ignored "-Wgnu-inline-cpp-without-extern" // debugbreak/debugbreak.h:50:16: error: 'gnu_inline' attribute without 'extern' in C++ treated as externally available, this changed in Clang 10 [-Werror,-Wgnu-inline-cpp-without-extern]
#           endif
#       else
#           if __clang_major__ >= 13
#               pragma clang diagnostic ignored "-Wgnu-inline-cpp-without-extern" // debugbreak/debugbreak.h:50:16: error: 'gnu_inline' attribute without 'extern' in C++ treated as externally available, this changed in Clang 10 [-Werror,-Wgnu-inline-cpp-without-extern]
#           endif
#       endif
#   elif defined(__GNUC__)
#   endif
// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/ext/debugbreak/debugbreak.h
//#   include <c4/ext/debugbreak/debugbreak.h>
#if !defined(DEBUG_BREAK_H) && !defined(_DEBUG_BREAK_H)
#error "amalgamate: file c4/ext/debugbreak/debugbreak.h must have been included at this point"
#endif /* DEBUG_BREAK_H */

#   define C4_DEBUG_BREAK() if(c4::is_debugger_attached()) { ::debug_break(); }
#   ifdef __clang__
#       pragma clang diagnostic pop
#   elif defined(__GNUC__)
#   endif
#endif

namespace c4 {
C4CORE_EXPORT bool is_debugger_attached();
} // namespace c4


//-----------------------------------------------------------------------------

#ifdef __clang__
    /* NOTE: using , ## __VA_ARGS__ to deal with zero-args calls to
     * variadic macros is not portable, but works in clang, gcc, msvc, icc.
     * clang requires switching off compiler warnings for pedantic mode.
     * @see http://stackoverflow.com/questions/32047685/variadic-macro-without-arguments */
#   pragma clang diagnostic push
#   pragma clang diagnostic ignored "-Wgnu-zero-variadic-macro-arguments" // warning: token pasting of ',' and __VA_ARGS__ is a GNU extension
#elif defined(__GNUC__)
    /* GCC also issues a warning for zero-args calls to variadic macros.
     * This warning is switched on with -pedantic and apparently there is no
     * easy way to turn it off as with clang. But marking this as a system
     * header works.
     * @see https://gcc.gnu.org/onlinedocs/cpp/System-Headers.html
     * @see http://stackoverflow.com/questions/35587137/ */
#   pragma GCC system_header
#endif


//-----------------------------------------------------------------------------

namespace c4 {

typedef enum : uint32_t {
    /** when an error happens and the debugger is attached, call C4_DEBUG_BREAK().
     * Without effect otherwise. */
    ON_ERROR_DEBUGBREAK = 0x01 << 0,
    /** when an error happens log a message. */
    ON_ERROR_LOG = 0x01 << 1,
    /** when an error happens invoke a callback if it was set with
     * set_error_callback(). */
    ON_ERROR_CALLBACK = 0x01 << 2,
    /** when an error happens call std::terminate(). */
    ON_ERROR_ABORT = 0x01 << 3,
    /** when an error happens and exceptions are enabled throw an exception.
     * Without effect otherwise. */
    ON_ERROR_THROW = 0x01 << 4,
    /** the default flags. */
    ON_ERROR_DEFAULTS = ON_ERROR_DEBUGBREAK|ON_ERROR_LOG|ON_ERROR_CALLBACK|ON_ERROR_ABORT
} ErrorFlags_e;
using error_flags = uint32_t;
C4CORE_EXPORT void set_error_flags(error_flags f);
C4CORE_EXPORT error_flags get_error_flags();


using error_callback_type = void (*)(const char* msg, size_t msg_size);
C4CORE_EXPORT void set_error_callback(error_callback_type cb);
C4CORE_EXPORT error_callback_type get_error_callback();


//-----------------------------------------------------------------------------
/** RAII class controling the error settings inside a scope. */
struct ScopedErrorSettings
{
    error_flags m_flags;
    error_callback_type m_callback;

    explicit ScopedErrorSettings(error_callback_type cb)
    :   m_flags(get_error_flags()),
        m_callback(get_error_callback())
    {
        set_error_callback(cb);
    }
    explicit ScopedErrorSettings(error_flags flags)
    :   m_flags(get_error_flags()),
        m_callback(get_error_callback())
    {
        set_error_flags(flags);
    }
    explicit ScopedErrorSettings(error_flags flags, error_callback_type cb)
    :   m_flags(get_error_flags()),
        m_callback(get_error_callback())
    {
        set_error_flags(flags);
        set_error_callback(cb);
    }
    ~ScopedErrorSettings()
    {
        set_error_flags(m_flags);
        set_error_callback(m_callback);
    }
};


//-----------------------------------------------------------------------------

/** source location */
struct srcloc;

C4CORE_EXPORT void handle_error(srcloc s, const char *fmt, ...);
C4CORE_EXPORT void handle_warning(srcloc s, const char *fmt, ...);


#   define C4_ERROR(msg, ...)                               \
    do {                                                    \
        if(c4::get_error_flags() & c4::ON_ERROR_DEBUGBREAK) \
        {                                                   \
            C4_DEBUG_BREAK()                                \
        }                                                   \
        c4::handle_error(C4_SRCLOC(), msg, ## __VA_ARGS__); \
    } while(0)


#   define C4_WARNING(msg, ...)                             \
    c4::handle_warning(C4_SRCLOC(), msg, ## __VA_ARGS__)


#if defined(C4_ERROR_SHOWS_FILELINE) && defined(C4_ERROR_SHOWS_FUNC)

struct srcloc
{
    const char *file = "";
    const char *func = "";
    int line = 0;
};
#define C4_SRCLOC() c4::srcloc{__FILE__, C4_PRETTY_FUNC, __LINE__}

#elif defined(C4_ERROR_SHOWS_FILELINE)

struct srcloc
{
    const char *file;
    int line;
};
#define C4_SRCLOC() c4::srcloc{__FILE__, __LINE__}

#elif ! defined(C4_ERROR_SHOWS_FUNC)

struct srcloc
{
};
#define C4_SRCLOC() c4::srcloc()

#else
#   error not implemented
#endif


//-----------------------------------------------------------------------------
// assertions

// Doxygen needs this so that only one definition counts
#ifdef _DOXYGEN_
    /** Explicitly enables assertions, independently of NDEBUG status.
     * This is meant to allow enabling assertions even when NDEBUG is defined.
     * Defaults to undefined.
     * @ingroup error_checking */
#   define C4_USE_ASSERT
    /** assert that a condition is true; this is turned off when NDEBUG
     * is defined and C4_USE_ASSERT is not true.
     * @ingroup error_checking  */
#   define C4_ASSERT
    /** same as C4_ASSERT(), additionally prints a printf-formatted message
     * @ingroup error_checking */
#   define C4_ASSERT_MSG
    /** evaluates to C4_NOEXCEPT when C4_XASSERT is disabled; otherwise, defaults
     * to noexcept
     * @ingroup error_checking */
#   define C4_NOEXCEPT_A
#endif // _DOXYGEN_

#ifndef C4_USE_ASSERT
#   ifdef NDEBUG
#       define C4_USE_ASSERT 0
#   else
#       define C4_USE_ASSERT 1
#   endif
#endif

#if C4_USE_ASSERT
#   define C4_ASSERT(cond) C4_CHECK(cond)
#   define C4_ASSERT_MSG(cond, /*fmt, */...) C4_CHECK_MSG(cond, ## __VA_ARGS__)
#   define C4_ASSERT_IF(predicate, cond) if(predicate) { C4_ASSERT(cond); }
#   define C4_NOEXCEPT_A C4_NOEXCEPT
#else
#   define C4_ASSERT(cond)
#   define C4_ASSERT_MSG(cond, /*fmt, */...)
#   define C4_ASSERT_IF(predicate, cond)
#   define C4_NOEXCEPT_A noexcept
#endif


//-----------------------------------------------------------------------------
// extreme assertions

// Doxygen needs this so that only one definition counts
#ifdef _DOXYGEN_
    /** Explicitly enables extreme assertions; this is meant to allow enabling
     * assertions even when NDEBUG is defined. Defaults to undefined.
     * @ingroup error_checking */
#   define C4_USE_XASSERT
    /** extreme assertion: can be switched off independently of
     * the regular assertion; use for example for bounds checking in hot code.
     * Turned on only when C4_USE_XASSERT is defined
     * @ingroup error_checking */
#   define C4_XASSERT
    /** same as C4_XASSERT(), and additionally prints a printf-formatted message
     * @ingroup error_checking */
#   define C4_XASSERT_MSG
    /** evaluates to C4_NOEXCEPT when C4_XASSERT is disabled; otherwise, defaults to noexcept
     * @ingroup error_checking */
#   define C4_NOEXCEPT_X
#endif // _DOXYGEN_

#ifndef C4_USE_XASSERT
#   define C4_USE_XASSERT C4_USE_ASSERT
#endif

#if C4_USE_XASSERT
#   define C4_XASSERT(cond) C4_CHECK(cond)
#   define C4_XASSERT_MSG(cond, /*fmt, */...) C4_CHECK_MSG(cond, ## __VA_ARGS__)
#   define C4_XASSERT_IF(predicate, cond) if(predicate) { C4_XASSERT(cond); }
#   define C4_NOEXCEPT_X C4_NOEXCEPT
#else
#   define C4_XASSERT(cond)
#   define C4_XASSERT_MSG(cond, /*fmt, */...)
#   define C4_XASSERT_IF(predicate, cond)
#   define C4_NOEXCEPT_X noexcept
#endif


//-----------------------------------------------------------------------------
// checks: never switched-off

/** Check that a condition is true, or raise an error when not
 * true. Unlike C4_ASSERT(), this check is not disabled in non-debug
 * builds.
 * @see C4_ASSERT
 * @ingroup error_checking
 *
 * @todo add constexpr-compatible compile-time assert:
 * https://akrzemi1.wordpress.com/2017/05/18/asserts-in-constexpr-functions/
 */
#define C4_CHECK(cond)                              \
    do {                                            \
        if(C4_UNLIKELY(!(cond)))                    \
        {                                           \
            C4_ERROR("check failed: %s", #cond);    \
        }                                           \
    } while(0)


/** like C4_CHECK(), and additionally log a printf-style message.
 * @see C4_CHECK
 * @ingroup error_checking */
#define C4_CHECK_MSG(cond, fmt, ...)                                    \
    do {                                                                \
        if(C4_UNLIKELY(!(cond)))                                        \
        {                                                               \
            C4_ERROR("check failed: " #cond "\n" fmt, ## __VA_ARGS__);  \
        }                                                               \
    } while(0)


//-----------------------------------------------------------------------------
// Common error conditions

#define C4_NOT_IMPLEMENTED() C4_ERROR("NOT IMPLEMENTED")
#define C4_NOT_IMPLEMENTED_MSG(/*msg, */...) C4_ERROR("NOT IMPLEMENTED: " ## __VA_ARGS__)
#define C4_NOT_IMPLEMENTED_IF(condition) do { if(C4_UNLIKELY(condition)) { C4_ERROR("NOT IMPLEMENTED"); } } while(0)
#define C4_NOT_IMPLEMENTED_IF_MSG(condition, /*msg, */...) do { if(C4_UNLIKELY(condition)) { C4_ERROR("NOT IMPLEMENTED: " ## __VA_ARGS__); } } while(0)

#define C4_NEVER_REACH() do { C4_ERROR("never reach this point"); C4_UNREACHABLE(); } while(0)
#define C4_NEVER_REACH_MSG(/*msg, */...) do { C4_ERROR("never reach this point: " ## __VA_ARGS__); C4_UNREACHABLE(); } while(0)



//-----------------------------------------------------------------------------
// helpers for warning suppression
// idea adapted from https://github.com/onqtam/doctest/


#ifdef C4_MSVC
#define C4_SUPPRESS_WARNING_MSVC_PUSH __pragma(warning(push))
#define C4_SUPPRESS_WARNING_MSVC(w)  __pragma(warning(disable : w))
#define C4_SUPPRESS_WARNING_MSVC_POP __pragma(warning(pop))
#define C4_SUPPRESS_WARNING_MSVC_WITH_PUSH(w)   \
    C4_SUPPRESS_WARNING_MSVC_PUSH               \
    C4_SUPPRESS_WARNING_MSVC(w)
#else // C4_MSVC
#define C4_SUPPRESS_WARNING_MSVC_PUSH
#define C4_SUPPRESS_WARNING_MSVC(w)
#define C4_SUPPRESS_WARNING_MSVC_POP
#define C4_SUPPRESS_WARNING_MSVC_WITH_PUSH(w)
#endif // C4_MSVC


#ifdef C4_CLANG
#define C4_PRAGMA_TO_STR(x) _Pragma(#x)
#define C4_SUPPRESS_WARNING_CLANG_PUSH _Pragma("clang diagnostic push")
#define C4_SUPPRESS_WARNING_CLANG(w) C4_PRAGMA_TO_STR(clang diagnostic ignored w)
#define C4_SUPPRESS_WARNING_CLANG_POP _Pragma("clang diagnostic pop")
#define C4_SUPPRESS_WARNING_CLANG_WITH_PUSH(w)  \
    C4_SUPPRESS_WARNING_CLANG_PUSH              \
    C4_SUPPRESS_WARNING_CLANG(w)
#else // C4_CLANG
#define C4_SUPPRESS_WARNING_CLANG_PUSH
#define C4_SUPPRESS_WARNING_CLANG(w)
#define C4_SUPPRESS_WARNING_CLANG_POP
#define C4_SUPPRESS_WARNING_CLANG_WITH_PUSH(w)
#endif // C4_CLANG


#ifdef C4_GCC
#define C4_PRAGMA_TO_STR(x) _Pragma(#x)
#define C4_SUPPRESS_WARNING_GCC_PUSH _Pragma("GCC diagnostic push")
#define C4_SUPPRESS_WARNING_GCC(w) C4_PRAGMA_TO_STR(GCC diagnostic ignored w)
#define C4_SUPPRESS_WARNING_GCC_POP _Pragma("GCC diagnostic pop")
#define C4_SUPPRESS_WARNING_GCC_WITH_PUSH(w)    \
    C4_SUPPRESS_WARNING_GCC_PUSH                \
    C4_SUPPRESS_WARNING_GCC(w)
#else // C4_GCC
#define C4_SUPPRESS_WARNING_GCC_PUSH
#define C4_SUPPRESS_WARNING_GCC(w)
#define C4_SUPPRESS_WARNING_GCC_POP
#define C4_SUPPRESS_WARNING_GCC_WITH_PUSH(w)
#endif // C4_GCC


#define C4_SUPPRESS_WARNING_GCC_CLANG_PUSH \
    C4_SUPPRESS_WARNING_GCC_PUSH     \
    C4_SUPPRESS_WARNING_CLANG_PUSH

#define C4_SUPPRESS_WARNING_GCC_CLANG(w) \
    C4_SUPPRESS_WARNING_GCC(w)     \
    C4_SUPPRESS_WARNING_CLANG(w)

#define C4_SUPPRESS_WARNING_GCC_CLANG_WITH_PUSH(w) \
    C4_SUPPRESS_WARNING_GCC_WITH_PUSH(w)     \
    C4_SUPPRESS_WARNING_CLANG_WITH_PUSH(w)

#define C4_SUPPRESS_WARNING_GCC_CLANG_POP \
    C4_SUPPRESS_WARNING_GCC_POP     \
    C4_SUPPRESS_WARNING_CLANG_POP

} // namespace c4

#ifdef __clang__
#   pragma clang diagnostic pop
#endif

#endif /* _C4_ERROR_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/error.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/memory_util.hpp
// https://github.com/biojppm/c4core/src/c4/memory_util.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_MEMORY_UTIL_HPP_
#define _C4_MEMORY_UTIL_HPP_

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/config.hpp
//#include "c4/config.hpp"
#if !defined(C4_CONFIG_HPP_) && !defined(_C4_CONFIG_HPP_)
#error "amalgamate: file c4/config.hpp must have been included at this point"
#endif /* C4_CONFIG_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/error.hpp
//#include "c4/error.hpp"
#if !defined(C4_ERROR_HPP_) && !defined(_C4_ERROR_HPP_)
#error "amalgamate: file c4/error.hpp must have been included at this point"
#endif /* C4_ERROR_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/compiler.hpp
//#include "c4/compiler.hpp"
#if !defined(C4_COMPILER_HPP_) && !defined(_C4_COMPILER_HPP_)
#error "amalgamate: file c4/compiler.hpp must have been included at this point"
#endif /* C4_COMPILER_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/cpu.hpp
//#include "c4/cpu.hpp"
#if !defined(C4_CPU_HPP_) && !defined(_C4_CPU_HPP_)
#error "amalgamate: file c4/cpu.hpp must have been included at this point"
#endif /* C4_CPU_HPP_ */

#ifdef C4_MSVC
#include <intrin.h>
#endif
//included above:
//#include <string.h>

#if (defined(__GNUC__) && __GNUC__ >= 10) || defined(__has_builtin)
#define _C4_USE_LSB_INTRINSIC(which) __has_builtin(which)
#define _C4_USE_MSB_INTRINSIC(which) __has_builtin(which)
#elif defined(C4_MSVC)
#define _C4_USE_LSB_INTRINSIC(which) true
#define _C4_USE_MSB_INTRINSIC(which) true
#else
// let's try our luck
#define _C4_USE_LSB_INTRINSIC(which) true
#define _C4_USE_MSB_INTRINSIC(which) true
#endif


/** @file memory_util.hpp Some memory utilities. */

namespace c4 {

/** set the given memory to zero */
C4_ALWAYS_INLINE void mem_zero(void* mem, size_t num_bytes)
{
    memset(mem, 0, num_bytes);
}
/** set the given memory to zero */
template<class T>
C4_ALWAYS_INLINE void mem_zero(T* mem, size_t num_elms)
{
    memset(mem, 0, sizeof(T) * num_elms);
}
/** set the given memory to zero */
template<class T>
C4_ALWAYS_INLINE void mem_zero(T* mem)
{
    memset(mem, 0, sizeof(T));
}

C4_ALWAYS_INLINE C4_CONST bool mem_overlaps(void const* a, void const* b, size_t sza, size_t szb)
{
    // thanks @timwynants
    return (((const char*)b + szb) > a && b < ((const char*)a+sza));
}

void mem_repeat(void* dest, void const* pattern, size_t pattern_size, size_t num_times);


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

template<class T>
C4_ALWAYS_INLINE C4_CONST bool is_aligned(T *ptr, uintptr_t alignment=alignof(T))
{
    return (uintptr_t(ptr) & (alignment - uintptr_t(1))) == uintptr_t(0);
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
// least significant bit

/** @name msb Compute the least significant bit
 * @note the input value must be nonzero
 * @note the input type must be unsigned
 */
/** @{ */

// https://graphics.stanford.edu/~seander/bithacks.html#ZerosOnRightLinear
#define _c4_lsb_fallback                                                \
    unsigned c = 0;                                                     \
    v = (v ^ (v - 1)) >> 1; /* Set v's trailing 0s to 1s and zero rest */ \
    for(; v; ++c)                                                       \
        v >>= 1;                                                        \
    return (unsigned) c

// u8
template<class I>
C4_CONSTEXPR14
auto lsb(I v) noexcept
    -> typename std::enable_if<sizeof(I) == 1u, unsigned>::type
{
    C4_STATIC_ASSERT(std::is_unsigned<I>::value);
    C4_ASSERT(v != 0);
    #if _C4_USE_LSB_INTRINSIC(__builtin_ctz)
        // upcast to use the intrinsic, it's cheaper.
        #ifdef C4_MSVC
            #if !defined(C4_CPU_ARM64) && !defined(C4_CPU_ARM)
                unsigned long bit;
                _BitScanForward(&bit, (unsigned long)v);
                return bit;
            #else
                _c4_lsb_fallback;
            #endif
        #else
            return (unsigned)__builtin_ctz((unsigned)v);
        #endif
    #else
        _c4_lsb_fallback;
    #endif
}

// u16
template<class I>
C4_CONSTEXPR14
auto lsb(I v) noexcept
    -> typename std::enable_if<sizeof(I) == 2u, unsigned>::type
{
    C4_STATIC_ASSERT(std::is_unsigned<I>::value);
    C4_ASSERT(v != 0);
    #if _C4_USE_LSB_INTRINSIC(__builtin_ctz)
        // upcast to use the intrinsic, it's cheaper.
        // Then remember that the upcast makes it to 31bits
        #ifdef C4_MSVC
            #if !defined(C4_CPU_ARM64) && !defined(C4_CPU_ARM)
                unsigned long bit;
                _BitScanForward(&bit, (unsigned long)v);
                return bit;
            #else
                _c4_lsb_fallback;
            #endif
        #else
            return (unsigned)__builtin_ctz((unsigned)v);
        #endif
    #else
        _c4_lsb_fallback;
    #endif
}

// u32
template<class I>
C4_CONSTEXPR14
auto lsb(I v) noexcept
    -> typename std::enable_if<sizeof(I) == 4u, unsigned>::type
{
    C4_STATIC_ASSERT(std::is_unsigned<I>::value);
    C4_ASSERT(v != 0);
    #if _C4_USE_LSB_INTRINSIC(__builtin_ctz)
        #ifdef C4_MSVC
            #if !defined(C4_CPU_ARM64) && !defined(C4_CPU_ARM)
                unsigned long bit;
                _BitScanForward(&bit, v);
                return bit;
            #else
                _c4_lsb_fallback;
            #endif
        #else
            return (unsigned)__builtin_ctz((unsigned)v);
        #endif
    #else
        _c4_lsb_fallback;
    #endif
}

// u64 in 64bits
template<class I>
C4_CONSTEXPR14
auto lsb(I v) noexcept
    -> typename std::enable_if<sizeof(I) == 8u && sizeof(unsigned long) == 8u, unsigned>::type
{
    C4_STATIC_ASSERT(std::is_unsigned<I>::value);
    C4_ASSERT(v != 0);
    #if _C4_USE_LSB_INTRINSIC(__builtin_ctzl)
        #if defined(C4_MSVC)
            #if !defined(C4_CPU_ARM64) && !defined(C4_CPU_ARM)
                unsigned long bit;
                _BitScanForward64(&bit, v);
                return bit;
            #else
                _c4_lsb_fallback;
            #endif
        #else
            return (unsigned)__builtin_ctzl((unsigned long)v);
        #endif
    #else
        _c4_lsb_fallback;
    #endif
}

// u64 in 32bits
template<class I>
C4_CONSTEXPR14
auto lsb(I v) noexcept
    -> typename std::enable_if<sizeof(I) == 8u && sizeof(unsigned long long) == 8u && sizeof(unsigned long) != sizeof(unsigned long long), unsigned>::type
{
    C4_STATIC_ASSERT(std::is_unsigned<I>::value);
    C4_ASSERT(v != 0);
    #if _C4_USE_LSB_INTRINSIC(__builtin_ctzll)
        #if defined(C4_MSVC)
            #if !defined(C4_CPU_X86) && !defined(C4_CPU_ARM64) && !defined(C4_CPU_ARM)
                unsigned long bit;
                _BitScanForward64(&bit, v);
                return bit;
            #else
                _c4_lsb_fallback;
            #endif
        #else
            return (unsigned)__builtin_ctzll((unsigned long long)v);
        #endif
    #else
        _c4_lsb_fallback;
    #endif
}

#undef _c4_lsb_fallback

/** @} */


namespace detail {
template<class I, I val, unsigned num_bits, bool finished> struct _lsb11;
template<class I, I val, unsigned num_bits>
struct _lsb11<I, val, num_bits, false>
{
    enum : unsigned { num = _lsb11<I, (val>>1), num_bits+I(1), (((val>>1)&I(1))!=I(0))>::num };
};
template<class I, I val, unsigned num_bits>
struct _lsb11<I, val, num_bits, true>
{
    enum : unsigned { num = num_bits };
};
} // namespace detail


/** TMP version of lsb(); this needs to be implemented with template
 * meta-programming because C++11 cannot use a constexpr function with
 * local variables
 * @see lsb */
template<class I, I number>
struct lsb11
{
    static_assert(number != 0, "lsb: number must be nonzero");
    enum : unsigned { value = detail::_lsb11<I, number, 0, ((number&I(1))!=I(0))>::num};
};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
// most significant bit


/** @name msb Compute the most significant bit
 * @note the input value must be nonzero
 * @note the input type must be unsigned
 */
/** @{ */


#define _c4_msb8_fallback                       \
    unsigned n = 0;                             \
    if(v & I(0xf0)) v >>= 4, n |= I(4);         \
    if(v & I(0x0c)) v >>= 2, n |= I(2);         \
    if(v & I(0x02)) v >>= 1, n |= I(1);         \
    return n

#define _c4_msb16_fallback                      \
    unsigned n = 0;                             \
    if(v & I(0xff00)) v >>= 8, n |= I(8);       \
    if(v & I(0x00f0)) v >>= 4, n |= I(4);       \
    if(v & I(0x000c)) v >>= 2, n |= I(2);       \
    if(v & I(0x0002)) v >>= 1, n |= I(1);       \
    return n

#define _c4_msb32_fallback                      \
    unsigned n = 0;                             \
    if(v & I(0xffff0000)) v >>= 16, n |= 16;    \
    if(v & I(0x0000ff00)) v >>= 8, n |= 8;      \
    if(v & I(0x000000f0)) v >>= 4, n |= 4;      \
    if(v & I(0x0000000c)) v >>= 2, n |= 2;      \
    if(v & I(0x00000002)) v >>= 1, n |= 1;      \
    return n

#define _c4_msb64_fallback                              \
    unsigned n = 0;                                     \
    if(v & I(0xffffffff00000000)) v >>= 32, n |= I(32); \
    if(v & I(0x00000000ffff0000)) v >>= 16, n |= I(16); \
    if(v & I(0x000000000000ff00)) v >>= 8, n |= I(8);   \
    if(v & I(0x00000000000000f0)) v >>= 4, n |= I(4);   \
    if(v & I(0x000000000000000c)) v >>= 2, n |= I(2);   \
    if(v & I(0x0000000000000002)) v >>= 1, n |= I(1);   \
    return n


// u8
template<class I>
C4_CONSTEXPR14
auto msb(I v) noexcept
    -> typename std::enable_if<sizeof(I) == 1u, unsigned>::type
{
    C4_STATIC_ASSERT(std::is_unsigned<I>::value);
    C4_ASSERT(v != 0);
    #if _C4_USE_MSB_INTRINSIC(__builtin_clz)
        // upcast to use the intrinsic, it's cheaper.
        // Then remember that the upcast makes it to 31bits
        #ifdef C4_MSVC
            #if !defined(C4_CPU_ARM64) && !defined(C4_CPU_ARM)
                unsigned long bit;
                _BitScanReverse(&bit, (unsigned long)v);
                return bit;
            #else
                _c4_msb8_fallback;
            #endif
        #else
            return 31u - (unsigned)__builtin_clz((unsigned)v);
        #endif
    #else
        _c4_msb8_fallback;
    #endif
}

// u16
template<class I>
C4_CONSTEXPR14
auto msb(I v) noexcept
    -> typename std::enable_if<sizeof(I) == 2u, unsigned>::type
{
    C4_STATIC_ASSERT(std::is_unsigned<I>::value);
    C4_ASSERT(v != 0);
    #if _C4_USE_MSB_INTRINSIC(__builtin_clz)
        // upcast to use the intrinsic, it's cheaper.
        // Then remember that the upcast makes it to 31bits
        #ifdef C4_MSVC
            #if !defined(C4_CPU_ARM64) && !defined(C4_CPU_ARM)
                unsigned long bit;
                _BitScanReverse(&bit, (unsigned long)v);
                return bit;
            #else
                _c4_msb16_fallback;
            #endif
        #else
            return 31u - (unsigned)__builtin_clz((unsigned)v);
        #endif
    #else
        _c4_msb16_fallback;
    #endif
}

// u32
template<class I>
C4_CONSTEXPR14
auto msb(I v) noexcept
    -> typename std::enable_if<sizeof(I) == 4u, unsigned>::type
{
    C4_STATIC_ASSERT(std::is_unsigned<I>::value);
    C4_ASSERT(v != 0);
    #if _C4_USE_MSB_INTRINSIC(__builtin_clz)
        #ifdef C4_MSVC
            #if !defined(C4_CPU_ARM64) && !defined(C4_CPU_ARM)
                unsigned long bit;
                _BitScanReverse(&bit, v);
                return bit;
            #else
                _c4_msb32_fallback;
            #endif
        #else
            return 31u - (unsigned)__builtin_clz((unsigned)v);
        #endif
    #else
        _c4_msb32_fallback;
    #endif
}

// u64 in 64bits
template<class I>
C4_CONSTEXPR14
auto msb(I v) noexcept
    -> typename std::enable_if<sizeof(I) == 8u && sizeof(unsigned long) == 8u, unsigned>::type
{
    C4_STATIC_ASSERT(std::is_unsigned<I>::value);
    C4_ASSERT(v != 0);
    #if _C4_USE_MSB_INTRINSIC(__builtin_clzl)
        #ifdef C4_MSVC
            #if !defined(C4_CPU_ARM64) && !defined(C4_CPU_ARM)
                unsigned long bit;
                _BitScanReverse64(&bit, v);
                return bit;
            #else
                _c4_msb64_fallback;
            #endif
        #else
            return 63u - (unsigned)__builtin_clzl((unsigned long)v);
        #endif
    #else
        _c4_msb64_fallback;
    #endif
}

// u64 in 32bits
template<class I>
C4_CONSTEXPR14
auto msb(I v) noexcept
    -> typename std::enable_if<sizeof(I) == 8u && sizeof(unsigned long long) == 8u && sizeof(unsigned long) != sizeof(unsigned long long), unsigned>::type
{
    C4_STATIC_ASSERT(std::is_unsigned<I>::value);
    C4_ASSERT(v != 0);
    #if _C4_USE_MSB_INTRINSIC(__builtin_clzll)
        #ifdef C4_MSVC
            #if !defined(C4_CPU_X86) && !defined(C4_CPU_ARM64) && !defined(C4_CPU_ARM)
                unsigned long bit;
                _BitScanReverse64(&bit, v);
                return bit;
            #else
                _c4_msb64_fallback;
            #endif
        #else
            return 63u - (unsigned)__builtin_clzll((unsigned long long)v);
        #endif
    #else
        _c4_msb64_fallback;
    #endif
}

#undef _c4_msb8_fallback
#undef _c4_msb16_fallback
#undef _c4_msb32_fallback
#undef _c4_msb64_fallback

/** @} */


namespace detail {
template<class I, I val, I num_bits, bool finished> struct _msb11;
template<class I, I val, I num_bits>
struct _msb11< I, val, num_bits, false>
{
    enum : unsigned { num = _msb11<I, (val>>1), num_bits+I(1), ((val>>1)==I(0))>::num };
};
template<class I, I val, I num_bits>
struct _msb11<I, val, num_bits, true>
{
    static_assert(val == 0, "bad implementation");
    enum : unsigned { num = (unsigned)(num_bits-1) };
};
} // namespace detail


/** TMP version of msb(); this needs to be implemented with template
 * meta-programming because C++11 cannot use a constexpr function with
 * local variables
 * @see msb */
template<class I, I number>
struct msb11
{
    enum : unsigned { value = detail::_msb11<I, number, 0, (number==I(0))>::num };
};



#undef _C4_USE_LSB_INTRINSIC
#undef _C4_USE_MSB_INTRINSIC

//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

// there is an implicit conversion below; it happens when E or B are
// narrower than int, and thus any operation will upcast the result to
// int, and then downcast to assign
C4_SUPPRESS_WARNING_GCC_CLANG_WITH_PUSH("-Wconversion")

/** integer power; this function is constexpr-14 because of the local
 * variables */
template<class B, class E>
C4_CONSTEXPR14 C4_CONST auto ipow(B base, E exponent) noexcept -> typename std::enable_if<std::is_signed<E>::value, B>::type
{
    C4_STATIC_ASSERT(std::is_integral<E>::value);
    B r = B(1);
    if(exponent >= 0)
    {
        for(E e = 0; e < exponent; ++e)
            r *= base;
    }
    else
    {
        exponent *= E(-1);
        for(E e = 0; e < exponent; ++e)
            r /= base;
    }
    return r;
}

/** integer power; this function is constexpr-14 because of the local
 * variables */
template<class B, B base, class E>
C4_CONSTEXPR14 C4_CONST auto ipow(E exponent) noexcept -> typename std::enable_if<std::is_signed<E>::value, B>::type
{
    C4_STATIC_ASSERT(std::is_integral<E>::value);
    B r = B(1);
    if(exponent >= 0)
    {
        for(E e = 0; e < exponent; ++e)
            r *= base;
    }
    else
    {
        exponent *= E(-1);
        for(E e = 0; e < exponent; ++e)
            r /= base;
    }
    return r;
}

/** integer power; this function is constexpr-14 because of the local
 * variables */
template<class B, class Base, Base base, class E>
C4_CONSTEXPR14 C4_CONST auto ipow(E exponent) noexcept -> typename std::enable_if<std::is_signed<E>::value, B>::type
{
    C4_STATIC_ASSERT(std::is_integral<E>::value);
    B r = B(1);
    B bbase = B(base);
    if(exponent >= 0)
    {
        for(E e = 0; e < exponent; ++e)
            r *= bbase;
    }
    else
    {
        exponent *= E(-1);
        for(E e = 0; e < exponent; ++e)
            r /= bbase;
    }
    return r;
}

/** integer power; this function is constexpr-14 because of the local
 * variables */
template<class B, class E>
C4_CONSTEXPR14 C4_CONST auto ipow(B base, E exponent) noexcept -> typename std::enable_if<!std::is_signed<E>::value, B>::type
{
    C4_STATIC_ASSERT(std::is_integral<E>::value);
    B r = B(1);
    for(E e = 0; e < exponent; ++e)
        r *= base;
    return r;
}

/** integer power; this function is constexpr-14 because of the local
 * variables */
template<class B, B base, class E>
C4_CONSTEXPR14 C4_CONST auto ipow(E exponent) noexcept -> typename std::enable_if<!std::is_signed<E>::value, B>::type
{
    C4_STATIC_ASSERT(std::is_integral<E>::value);
    B r = B(1);
    for(E e = 0; e < exponent; ++e)
        r *= base;
    return r;
}
/** integer power; this function is constexpr-14 because of the local
 * variables */
template<class B, class Base, Base base, class E>
C4_CONSTEXPR14 C4_CONST auto ipow(E exponent) noexcept -> typename std::enable_if<!std::is_signed<E>::value, B>::type
{
    C4_STATIC_ASSERT(std::is_integral<E>::value);
    B r = B(1);
    B bbase = B(base);
    for(E e = 0; e < exponent; ++e)
        r *= bbase;
    return r;
}

C4_SUPPRESS_WARNING_GCC_CLANG_POP


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** return a mask with all bits set [first_bit,last_bit[; this function
 * is constexpr-14 because of the local variables */
template<class I>
C4_CONSTEXPR14 I contiguous_mask(I first_bit, I last_bit)
{
    I r = 0;
    for(I i = first_bit; i < last_bit; ++i)
    {
        r |= (I(1) << i);
    }
    return r;
}


namespace detail {

template<class I, I val, I first, I last, bool finished>
struct _ctgmsk11;

template<class I, I val, I first, I last>
struct _ctgmsk11< I, val, first, last, true>
{
    enum : I { value = _ctgmsk11<I, val|(I(1)<<first), first+I(1), last, (first+1!=last)>::value };
};

template<class I, I val, I first, I last>
struct _ctgmsk11< I, val, first, last, false>
{
    enum : I { value = val };
};

} // namespace detail


/** TMP version of contiguous_mask(); this needs to be implemented with template
 * meta-programming because C++11 cannot use a constexpr function with
 * local variables
 * @see contiguous_mask */
template<class I, I first_bit, I last_bit>
struct contiguous_mask11
{
    enum : I { value = detail::_ctgmsk11<I, I(0), first_bit, last_bit, (first_bit!=last_bit)>::value };
};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
/** use Empty Base Class Optimization to reduce the size of a pair of
 * potentially empty types*/

namespace detail {
typedef enum {
    tpc_same,
    tpc_same_empty,
    tpc_both_empty,
    tpc_first_empty,
    tpc_second_empty,
    tpc_general
} TightPairCase_e;

template<class First, class Second>
constexpr TightPairCase_e tpc_which_case()
{
    return std::is_same<First, Second>::value ?
               std::is_empty<First>::value ?
                   tpc_same_empty
                   :
                   tpc_same
               :
               std::is_empty<First>::value && std::is_empty<Second>::value ?
                   tpc_both_empty
                   :
                   std::is_empty<First>::value ?
                       tpc_first_empty
                       :
                       std::is_empty<Second>::value ?
                           tpc_second_empty
                           :
                           tpc_general
           ;
}

template<class First, class Second, TightPairCase_e Case>
struct tight_pair
{
private:

    First m_first;
    Second m_second;

public:

    using first_type = First;
    using second_type = Second;

    tight_pair() : m_first(), m_second() {}
    tight_pair(First const& f, Second const& s) : m_first(f), m_second(s) {}

    C4_ALWAYS_INLINE C4_CONSTEXPR14 First       & first ()       { return m_first; }
    C4_ALWAYS_INLINE C4_CONSTEXPR14 First  const& first () const { return m_first; }
    C4_ALWAYS_INLINE C4_CONSTEXPR14 Second      & second()       { return m_second; }
    C4_ALWAYS_INLINE C4_CONSTEXPR14 Second const& second() const { return m_second; }
};

template<class First, class Second>
struct tight_pair<First, Second, tpc_same_empty> : public First
{
    static_assert(std::is_same<First, Second>::value, "bad implementation");

    using first_type = First;
    using second_type = Second;

    tight_pair() : First() {}
    tight_pair(First const& f, Second const& /*s*/) : First(f) {}

    C4_ALWAYS_INLINE C4_CONSTEXPR14 First      & first ()       { return static_cast<First      &>(*this); }
    C4_ALWAYS_INLINE C4_CONSTEXPR14 First const& first () const { return static_cast<First const&>(*this); }
    C4_ALWAYS_INLINE C4_CONSTEXPR14 Second      & second()       { return reinterpret_cast<Second      &>(*this); }
    C4_ALWAYS_INLINE C4_CONSTEXPR14 Second const& second() const { return reinterpret_cast<Second const&>(*this); }
};

template<class First, class Second>
struct tight_pair<First, Second, tpc_both_empty> : public First, public Second
{
    using first_type = First;
    using second_type = Second;

    tight_pair() : First(), Second() {}
    tight_pair(First const& f, Second const& s) : First(f), Second(s) {}

    C4_ALWAYS_INLINE C4_CONSTEXPR14 First      & first ()       { return static_cast<First      &>(*this); }
    C4_ALWAYS_INLINE C4_CONSTEXPR14 First const& first () const { return static_cast<First const&>(*this); }
    C4_ALWAYS_INLINE C4_CONSTEXPR14 Second      & second()       { return static_cast<Second      &>(*this); }
    C4_ALWAYS_INLINE C4_CONSTEXPR14 Second const& second() const { return static_cast<Second const&>(*this); }
};

template<class First, class Second>
struct tight_pair<First, Second, tpc_same> : public First
{
    Second m_second;

    using first_type = First;
    using second_type = Second;

    tight_pair() : First() {}
    tight_pair(First const& f, Second const& s) : First(f), m_second(s) {}

    C4_ALWAYS_INLINE C4_CONSTEXPR14 First      & first ()       { return static_cast<First      &>(*this); }
    C4_ALWAYS_INLINE C4_CONSTEXPR14 First const& first () const { return static_cast<First const&>(*this); }
    C4_ALWAYS_INLINE C4_CONSTEXPR14 Second      & second()       { return m_second; }
    C4_ALWAYS_INLINE C4_CONSTEXPR14 Second const& second() const { return m_second; }
};

template<class First, class Second>
struct tight_pair<First, Second, tpc_first_empty> : public First
{
    Second m_second;

    using first_type = First;
    using second_type = Second;

    tight_pair() : First(), m_second() {}
    tight_pair(First const& f, Second const& s) : First(f), m_second(s) {}

    C4_ALWAYS_INLINE C4_CONSTEXPR14 First      & first ()       { return static_cast<First      &>(*this); }
    C4_ALWAYS_INLINE C4_CONSTEXPR14 First const& first () const { return static_cast<First const&>(*this); }
    C4_ALWAYS_INLINE C4_CONSTEXPR14 Second      & second()       { return m_second; }
    C4_ALWAYS_INLINE C4_CONSTEXPR14 Second const& second() const { return m_second; }
};

template<class First, class Second>
struct tight_pair<First, Second, tpc_second_empty> : public Second
{
    First m_first;

    using first_type = First;
    using second_type = Second;

    tight_pair() : Second(), m_first() {}
    tight_pair(First const& f, Second const& s) : Second(s), m_first(f) {}

    C4_ALWAYS_INLINE C4_CONSTEXPR14 First      & first ()       { return m_first; }
    C4_ALWAYS_INLINE C4_CONSTEXPR14 First const& first () const { return m_first; }
    C4_ALWAYS_INLINE C4_CONSTEXPR14 Second      & second()       { return static_cast<Second      &>(*this); }
    C4_ALWAYS_INLINE C4_CONSTEXPR14 Second const& second() const { return static_cast<Second const&>(*this); }
};

} // namespace detail

template<class First, class Second>
using tight_pair = detail::tight_pair<First, Second, detail::tpc_which_case<First,Second>()>;

} // namespace c4

#endif /* _C4_MEMORY_UTIL_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/memory_util.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/memory_resource.hpp
// https://github.com/biojppm/c4core/src/c4/memory_resource.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_MEMORY_RESOURCE_HPP_
#define _C4_MEMORY_RESOURCE_HPP_

/** @file memory_resource.hpp Provides facilities to allocate typeless
 *  memory, via the memory resource model consecrated with C++17. */

/** @defgroup memory memory utilities */

/** @defgroup raw_memory_alloc Raw memory allocation
 * @ingroup memory
 */

/** @defgroup memory_resources Memory resources
 * @ingroup memory
 */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/config.hpp
//#include "c4/config.hpp"
#if !defined(C4_CONFIG_HPP_) && !defined(_C4_CONFIG_HPP_)
#error "amalgamate: file c4/config.hpp must have been included at this point"
#endif /* C4_CONFIG_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/error.hpp
//#include "c4/error.hpp"
#if !defined(C4_ERROR_HPP_) && !defined(_C4_ERROR_HPP_)
#error "amalgamate: file c4/error.hpp must have been included at this point"
#endif /* C4_ERROR_HPP_ */


namespace c4 {

// need these forward decls here
struct MemoryResource;
struct MemoryResourceMalloc;
struct MemoryResourceStack;
MemoryResourceMalloc* get_memory_resource_malloc();
MemoryResourceStack* get_memory_resource_stack();
namespace detail { MemoryResource*& get_memory_resource(); }


// c-style allocation ---------------------------------------------------------

// this API provides aligned allocation functions.
// These functions forward the call to a user-modifiable function.


// aligned allocation.

/** Aligned allocation. Merely calls the current get_aalloc() function.
 * @see get_aalloc()
 * @ingroup raw_memory_alloc */
void* aalloc(size_t sz, size_t alignment);

/** Aligned free. Merely calls the current get_afree() function.
 * @see get_afree()
 * @ingroup raw_memory_alloc */
void afree(void* ptr);

/** Aligned reallocation. Merely calls the current get_arealloc() function.
 * @see get_arealloc()
 * @ingroup raw_memory_alloc */
void* arealloc(void* ptr, size_t oldsz, size_t newsz, size_t alignment);


// allocation setup facilities.

/** Function pointer type for aligned allocation
 * @see set_aalloc()
 * @ingroup raw_memory_alloc */
using aalloc_pfn = void* (*)(size_t size, size_t alignment);

/** Function pointer type for aligned deallocation
 * @see set_afree()
 * @ingroup raw_memory_alloc */
using afree_pfn = void  (*)(void *ptr);

/** Function pointer type for aligned reallocation
 * @see set_arealloc()
 * @ingroup raw_memory_alloc */
using arealloc_pfn = void* (*)(void *ptr, size_t oldsz, size_t newsz, size_t alignment);


// allocation function pointer setters/getters

/** Set the global aligned allocation function.
 * @see aalloc()
 * @see get_aalloc()
 * @ingroup raw_memory_alloc */
void set_aalloc(aalloc_pfn fn);

/** Set the global aligned deallocation function.
 * @see afree()
 * @see get_afree()
 * @ingroup raw_memory_alloc */
void set_afree(afree_pfn fn);

/** Set the global aligned reallocation function.
 * @see arealloc()
 * @see get_arealloc()
 * @ingroup raw_memory_alloc */
void set_arealloc(arealloc_pfn fn);


/** Get the global aligned reallocation function.
 * @see arealloc()
 * @ingroup raw_memory_alloc */
aalloc_pfn get_aalloc();

/** Get the global aligned deallocation function.
 * @see afree()
 * @ingroup raw_memory_alloc */
afree_pfn get_afree();

/** Get the global aligned reallocation function.
 * @see arealloc()
 * @ingroup raw_memory_alloc */
arealloc_pfn get_arealloc();


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
// c++-style allocation -------------------------------------------------------

/** C++17-style memory_resource base class. See http://en.cppreference.com/w/cpp/experimental/memory_resource
 * @ingroup memory_resources */
struct MemoryResource
{
    const char *name = nullptr;
    virtual ~MemoryResource() {}

    void* allocate(size_t sz, size_t alignment=alignof(max_align_t), void *hint=nullptr)
    {
        void *mem = this->do_allocate(sz, alignment, hint);
        C4_CHECK_MSG(mem != nullptr, "could not allocate %lu bytes", sz);
        return mem;
    }

    void* reallocate(void* ptr, size_t oldsz, size_t newsz, size_t alignment=alignof(max_align_t))
    {
        void *mem = this->do_reallocate(ptr, oldsz, newsz, alignment);
        C4_CHECK_MSG(mem != nullptr, "could not reallocate from %lu to %lu bytes", oldsz, newsz);
        return mem;
    }

    void deallocate(void* ptr, size_t sz, size_t alignment=alignof(max_align_t))
    {
        this->do_deallocate(ptr, sz, alignment);
    }

protected:

    virtual void* do_allocate(size_t sz, size_t alignment, void* hint) = 0;
    virtual void* do_reallocate(void* ptr, size_t oldsz, size_t newsz, size_t alignment) = 0;
    virtual void  do_deallocate(void* ptr, size_t sz, size_t alignment) = 0;

};

/** get the current global memory resource. To avoid static initialization
 * order problems, this is implemented using a function call to ensure
 * that it is available when first used.
 * @ingroup memory_resources */
C4_ALWAYS_INLINE MemoryResource* get_memory_resource()
{
    return detail::get_memory_resource();
}

/** set the global memory resource
 * @ingroup memory_resources */
C4_ALWAYS_INLINE void set_memory_resource(MemoryResource* mr)
{
    C4_ASSERT(mr != nullptr);
    detail::get_memory_resource() = mr;
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
/** A c4::aalloc-based memory resource. Thread-safe if the implementation
 * called by c4::aalloc() is safe.
 * @ingroup memory_resources */
struct MemoryResourceMalloc : public MemoryResource
{

    MemoryResourceMalloc() { name = "malloc"; }
    virtual ~MemoryResourceMalloc() override {}

protected:

    virtual void* do_allocate(size_t sz, size_t alignment, void *hint) override
    {
        C4_UNUSED(hint);
        return c4::aalloc(sz, alignment);
    }

    virtual void  do_deallocate(void* ptr, size_t sz, size_t alignment) override
    {
        C4_UNUSED(sz);
        C4_UNUSED(alignment);
        c4::afree(ptr);
    }

    virtual void* do_reallocate(void* ptr, size_t oldsz, size_t newsz, size_t alignment) override
    {
        return c4::arealloc(ptr, oldsz, newsz, alignment);
    }

};

/** returns a malloc-based memory resource
 * @ingroup memory_resources */
C4_ALWAYS_INLINE MemoryResourceMalloc* get_memory_resource_malloc()
{
    /** @todo use a nifty counter:
     * https://en.wikibooks.org/wiki/More_C%2B%2B_Idioms/Nifty_Counter */
    static MemoryResourceMalloc mr;
    return &mr;
}

namespace detail {
C4_ALWAYS_INLINE MemoryResource* & get_memory_resource()
{
    /** @todo use a nifty counter:
     * https://en.wikibooks.org/wiki/More_C%2B%2B_Idioms/Nifty_Counter */
    thread_local static MemoryResource* mr = get_memory_resource_malloc();
    return mr;
}
} // namespace detail


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

namespace detail {

/** Allows a memory resource to obtain its memory from another memory resource.
 * @ingroup memory_resources */
struct DerivedMemoryResource : public MemoryResource
{
public:

    DerivedMemoryResource(MemoryResource *mr_=nullptr) : m_local(mr_ ? mr_ : get_memory_resource()) {}

private:

    MemoryResource *m_local;

protected:

    virtual void* do_allocate(size_t sz, size_t alignment, void* hint) override
    {
        return m_local->allocate(sz, alignment, hint);
    }

    virtual void* do_reallocate(void* ptr, size_t oldsz, size_t newsz, size_t alignment) override
    {
        return m_local->reallocate(ptr, oldsz, newsz, alignment);
    }

    virtual void do_deallocate(void* ptr, size_t sz, size_t alignment) override
    {
        return m_local->deallocate(ptr, sz, alignment);
    }
};

/** Provides common facilities for memory resource consisting of a single memory block
 * @ingroup memory_resources */
struct _MemoryResourceSingleChunk : public DerivedMemoryResource
{

    C4_NO_COPY_OR_MOVE(_MemoryResourceSingleChunk);

    using impl_type = DerivedMemoryResource;

public:

    _MemoryResourceSingleChunk(MemoryResource *impl=nullptr) : DerivedMemoryResource(impl) { name = "linear_malloc"; }

    /** initialize with owned memory, allocated from the given (or the global) memory resource */
    _MemoryResourceSingleChunk(size_t sz, MemoryResource *impl=nullptr) : _MemoryResourceSingleChunk(impl) { acquire(sz); }
    /** initialize with borrowed memory */
    _MemoryResourceSingleChunk(void *mem, size_t sz) : _MemoryResourceSingleChunk() { acquire(mem, sz); }

    virtual ~_MemoryResourceSingleChunk() override { release(); }

public:

    void const* mem() const { return m_mem; }

    size_t capacity() const { return m_size; }
    size_t size() const { return m_pos; }
    size_t slack() const { C4_ASSERT(m_size >= m_pos); return m_size - m_pos; }

public:

    char  *m_mem{nullptr};
    size_t m_size{0};
    size_t m_pos{0};
    bool   m_owner;

public:

    /** set the internal pointer to the beginning of the linear buffer */
    void clear() { m_pos = 0; }

    /** initialize with owned memory, allocated from the global memory resource */
    void acquire(size_t sz);
    /** initialize with borrowed memory */
    void acquire(void *mem, size_t sz);
    /** release the memory */
    void release();

};

} // namespace detail


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
/** provides a linear memory resource. Allocates incrementally from a linear
 * buffer, without ever deallocating. Deallocations are a no-op, and the
 * memory is freed only when the resource is release()d. The memory used by
 * this object can be either owned or borrowed. When borrowed, no calls to
 * malloc/free take place.
 *
 * @ingroup memory_resources */
struct MemoryResourceLinear : public detail::_MemoryResourceSingleChunk
{

    C4_NO_COPY_OR_MOVE(MemoryResourceLinear);

public:

    using detail::_MemoryResourceSingleChunk::_MemoryResourceSingleChunk;

protected:

    virtual void* do_allocate(size_t sz, size_t alignment, void *hint) override;
    virtual void  do_deallocate(void* ptr, size_t sz, size_t alignment) override;
    virtual void* do_reallocate(void* ptr, size_t oldsz, size_t newsz, size_t alignment) override;
};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
/** provides a stack-type malloc-based memory resource.
 * @ingroup memory_resources */
struct MemoryResourceStack : public detail::_MemoryResourceSingleChunk
{

    C4_NO_COPY_OR_MOVE(MemoryResourceStack);

public:

    using detail::_MemoryResourceSingleChunk::_MemoryResourceSingleChunk;

protected:

    virtual void* do_allocate(size_t sz, size_t alignment, void *hint) override;
    virtual void  do_deallocate(void* ptr, size_t sz, size_t alignment) override;
    virtual void* do_reallocate(void* ptr, size_t oldsz, size_t newsz, size_t alignment) override;
};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
/** provides a linear array-based memory resource.
 * @see MemoryResourceLinear
 * @ingroup memory_resources */
template<size_t N>
struct MemoryResourceLinearArr : public MemoryResourceLinear
{
    #ifdef _MSC_VER
    #pragma warning(push)
    #pragma warning(disable: 4324) // structure was padded due to alignment specifier
    #endif
    alignas(alignof(max_align_t)) char m_arr[N];
    #ifdef _MSC_VER
    #pragma warning(pop)
    #endif
    MemoryResourceLinearArr() : MemoryResourceLinear(m_arr, N) { name = "linear_arr"; }
};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
struct AllocationCounts
{
    struct Item
    {
        ssize_t allocs;
        ssize_t size;

        void add(size_t sz)
        {
            ++allocs;
            size += static_cast<ssize_t>(sz);
        }
        void rem(size_t sz)
        {
            --allocs;
            size -= static_cast<ssize_t>(sz);
        }
        Item max(Item const& that) const
        {
            Item r(*this);
            r.allocs = r.allocs > that.allocs ? r.allocs : that.allocs;
            r.size = r.size > that.size ? r.size : that.size;
            return r;
        }
    };

    Item curr  = {0, 0};
    Item total = {0, 0};
    Item max   = {0, 0};

    void clear_counts()
    {
        curr  = {0, 0};
        total = {0, 0};
        max   = {0, 0};
    }

    void update(AllocationCounts const& that)
    {
        curr.allocs += that.curr.allocs;
        curr.size += that.curr.size;
        total.allocs += that.total.allocs;
        total.size += that.total.size;
        max.allocs += that.max.allocs;
        max.size += that.max.size;
    }

    void add_counts(void* ptr, size_t sz)
    {
        if(ptr == nullptr) return;
        curr.add(sz);
        total.add(sz);
        max = max.max(curr);
    }

    void rem_counts(void *ptr, size_t sz)
    {
        if(ptr == nullptr) return;
        curr.rem(sz);
    }

    AllocationCounts operator- (AllocationCounts const& that) const
    {
        AllocationCounts r(*this);
        r.curr.allocs -= that.curr.allocs;
        r.curr.size -= that.curr.size;
        r.total.allocs -= that.total.allocs;
        r.total.size -= that.total.size;
        r.max.allocs -= that.max.allocs;
        r.max.size -= that.max.size;
        return r;
    }

    AllocationCounts operator+ (AllocationCounts const& that) const
    {
        AllocationCounts r(*this);
        r.curr.allocs += that.curr.allocs;
        r.curr.size += that.curr.size;
        r.total.allocs += that.total.allocs;
        r.total.size += that.total.size;
        r.max.allocs += that.max.allocs;
        r.max.size += that.max.size;
        return r;
    }
};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
/** a MemoryResource which latches onto another MemoryResource
 * and counts allocations and sizes.
 * @ingroup memory_resources */
class MemoryResourceCounts : public MemoryResource
{
public:

    MemoryResourceCounts() : m_resource(get_memory_resource())
    {
        C4_ASSERT(m_resource != this);
        name = "MemoryResourceCounts";
    }
    MemoryResourceCounts(MemoryResource *res) : m_resource(res)
    {
        C4_ASSERT(m_resource != this);
        name = "MemoryResourceCounts";
    }

    MemoryResource *resource() { return m_resource; }
    AllocationCounts const& counts() const { return m_counts; }

protected:

    MemoryResource *m_resource;
    AllocationCounts m_counts;

protected:

    virtual void* do_allocate(size_t sz, size_t alignment, void * /*hint*/) override
    {
        void *ptr = m_resource->allocate(sz, alignment);
        m_counts.add_counts(ptr, sz);
        return ptr;
    }

    virtual void  do_deallocate(void* ptr, size_t sz, size_t alignment) override
    {
        m_counts.rem_counts(ptr, sz);
        m_resource->deallocate(ptr, sz, alignment);
    }

    virtual void* do_reallocate(void* ptr, size_t oldsz, size_t newsz, size_t alignment) override
    {
        m_counts.rem_counts(ptr, oldsz);
        void* nptr = m_resource->reallocate(ptr, oldsz, newsz, alignment);
        m_counts.add_counts(nptr, newsz);
        return nptr;
    }

};

//-----------------------------------------------------------------------------
/** RAII class which binds a memory resource with a scope duration.
 * @ingroup memory_resources */
struct ScopedMemoryResource
{
    MemoryResource *m_original;

    ScopedMemoryResource(MemoryResource *r)
    :
        m_original(get_memory_resource())
    {
        set_memory_resource(r);
    }

    ~ScopedMemoryResource()
    {
        set_memory_resource(m_original);
    }
};

//-----------------------------------------------------------------------------
/** RAII class which counts allocations and frees inside a scope. Can
 * optionally set also the memory resource to be used.
 * @ingroup memory_resources */
struct ScopedMemoryResourceCounts
{
    MemoryResourceCounts mr;

    ScopedMemoryResourceCounts() : mr()
    {
        set_memory_resource(&mr);
    }
    ScopedMemoryResourceCounts(MemoryResource *m) : mr(m)
    {
        set_memory_resource(&mr);
    }
    ~ScopedMemoryResourceCounts()
    {
        set_memory_resource(mr.resource());
    }
};

} // namespace c4

#endif /* _C4_MEMORY_RESOURCE_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/memory_resource.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/ctor_dtor.hpp
// https://github.com/biojppm/c4core/src/c4/ctor_dtor.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_CTOR_DTOR_HPP_
#define _C4_CTOR_DTOR_HPP_

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/preprocessor.hpp
//#include "c4/preprocessor.hpp"
#if !defined(C4_PREPROCESSOR_HPP_) && !defined(_C4_PREPROCESSOR_HPP_)
#error "amalgamate: file c4/preprocessor.hpp must have been included at this point"
#endif /* C4_PREPROCESSOR_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/language.hpp
//#include "c4/language.hpp"
#if !defined(C4_LANGUAGE_HPP_) && !defined(_C4_LANGUAGE_HPP_)
#error "amalgamate: file c4/language.hpp must have been included at this point"
#endif /* C4_LANGUAGE_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/memory_util.hpp
//#include "c4/memory_util.hpp"
#if !defined(C4_MEMORY_UTIL_HPP_) && !defined(_C4_MEMORY_UTIL_HPP_)
#error "amalgamate: file c4/memory_util.hpp must have been included at this point"
#endif /* C4_MEMORY_UTIL_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/error.hpp
//#include "c4/error.hpp"
#if !defined(C4_ERROR_HPP_) && !defined(_C4_ERROR_HPP_)
#error "amalgamate: file c4/error.hpp must have been included at this point"
#endif /* C4_ERROR_HPP_ */


//included above:
//#include <type_traits>
//included above:
//#include <utility> // std::forward

/** @file ctor_dtor.hpp object construction and destruction facilities.
 * Some of these are not yet available in C++11. */

namespace c4 {

/** default-construct an object, trivial version */
template <class U> C4_ALWAYS_INLINE typename std::enable_if<std::is_trivially_default_constructible<U>::value, void>::type
construct(U *ptr) noexcept
{
    memset(ptr, 0, sizeof(U));
}
/** default-construct an object, non-trivial version */
template<class U> C4_ALWAYS_INLINE typename std ::enable_if< ! std::is_trivially_default_constructible<U>::value, void>::type
construct(U* ptr) noexcept
{
    new ((void*)ptr) U();
}

/** default-construct n objects, trivial version */
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if<std::is_trivially_default_constructible<U>::value, void>::type
construct_n(U* ptr, I n) noexcept
{
    memset(ptr, 0, n * sizeof(U));
}
/** default-construct n objects, non-trivial version */
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if< ! std::is_trivially_default_constructible<U>::value, void>::type
construct_n(U* ptr, I n) noexcept
{
    for(I i = 0; i < n; ++i)
    {
        new ((void*)(ptr + i)) U();
    }
}

#ifdef __clang__
#   pragma clang diagnostic push
#elif defined(__GNUC__)
#   pragma GCC diagnostic push
#   if __GNUC__ >= 6
#       pragma GCC diagnostic ignored "-Wnull-dereference"
#   endif
#endif

template<class U, class ...Args>
inline void construct(U* ptr, Args&&... args)
{
    new ((void*)ptr) U(std::forward<Args>(args)...);
}
template<class U, class I, class ...Args>
inline void construct_n(U* ptr, I n, Args&&... args)
{
    for(I i = 0; i < n; ++i)
    {
        new ((void*)(ptr + i)) U(args...);
    }
}

#ifdef __clang__
#   pragma clang diagnostic pop
#elif defined(__GNUC__)
#   pragma GCC diagnostic pop
#endif


//-----------------------------------------------------------------------------
// copy-construct

template<class U> C4_ALWAYS_INLINE typename std::enable_if<std::is_trivially_copy_constructible<U>::value, void>::type
copy_construct(U* dst, U const* src) noexcept
{
    C4_ASSERT(dst != src);
    memcpy(dst, src, sizeof(U));
}
template<class U> C4_ALWAYS_INLINE typename std::enable_if< ! std::is_trivially_copy_constructible<U>::value, void>::type
copy_construct(U* dst, U const* src)
{
    C4_ASSERT(dst != src);
    new ((void*)dst) U(*src);
}
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if<std::is_trivially_copy_constructible<U>::value, void>::type
copy_construct_n(U* dst, U const* src, I n) noexcept
{
    C4_ASSERT(dst != src);
    memcpy(dst, src, n * sizeof(U));
}
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if< ! std::is_trivially_copy_constructible<U>::value, void>::type
copy_construct_n(U* dst, U const* src, I n)
{
    C4_ASSERT(dst != src);
    for(I i = 0; i < n; ++i)
    {
        new ((void*)(dst + i)) U(*(src + i));
    }
}

template<class U> C4_ALWAYS_INLINE typename std::enable_if<std::is_scalar<U>::value, void>::type
copy_construct(U* dst, U src) noexcept // pass by value for scalar types
{
    *dst = src;
}
template<class U> C4_ALWAYS_INLINE typename std::enable_if< ! std::is_scalar<U>::value, void>::type
copy_construct(U* dst, U const& src) // pass by reference for non-scalar types
{
    C4_ASSERT(dst != &src);
    new ((void*)dst) U(src);
}
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if<std::is_scalar<U>::value, void>::type
copy_construct_n(U* dst, U src, I n) noexcept // pass by value for scalar types
{
    for(I i = 0; i < n; ++i)
    {
        dst[i] = src;
    }
}
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if< ! std::is_scalar<U>::value, void>::type
copy_construct_n(U* dst, U const& src, I n) // pass by reference for non-scalar types
{
    C4_ASSERT(dst != &src);
    for(I i = 0; i < n; ++i)
    {
        new ((void*)(dst + i)) U(src);
    }
}

template<class U, size_t N>
C4_ALWAYS_INLINE void copy_construct(U (&dst)[N], U const (&src)[N]) noexcept
{
    copy_construct_n(dst, src, N);
}

//-----------------------------------------------------------------------------
// copy-assign

template<class U> C4_ALWAYS_INLINE typename std::enable_if<std::is_trivially_copy_assignable<U>::value, void>::type
copy_assign(U* dst, U const* src) noexcept
{
    C4_ASSERT(dst != src);
    memcpy(dst, src, sizeof(U));
}
template<class U> C4_ALWAYS_INLINE typename std::enable_if< ! std::is_trivially_copy_assignable<U>::value, void>::type
copy_assign(U* dst, U const* src) noexcept
{
    C4_ASSERT(dst != src);
    *dst = *src;
}
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if<std::is_trivially_copy_assignable<U>::value, void>::type
copy_assign_n(U* dst, U const* src, I n) noexcept
{
    C4_ASSERT(dst != src);
    memcpy(dst, src, n * sizeof(U));
}
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if< ! std::is_trivially_copy_assignable<U>::value, void>::type
copy_assign_n(U* dst, U const* src, I n) noexcept
{
    C4_ASSERT(dst != src);
    for(I i = 0; i < n; ++i)
    {
        dst[i] = src[i];
    }
}

template<class U> C4_ALWAYS_INLINE typename std::enable_if<std::is_scalar<U>::value, void>::type
copy_assign(U* dst, U src) noexcept // pass by value for scalar types
{
    *dst = src;
}
template<class U> C4_ALWAYS_INLINE typename std::enable_if< ! std::is_scalar<U>::value, void>::type
copy_assign(U* dst, U const& src) noexcept // pass by reference for non-scalar types
{
    C4_ASSERT(dst != &src);
    *dst = src;
}
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if<std::is_scalar<U>::value, void>::type
copy_assign_n(U* dst, U src, I n) noexcept // pass by value for scalar types
{
    for(I i = 0; i < n; ++i)
    {
        dst[i] = src;
    }
}
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if< ! std::is_scalar<U>::value, void>::type
copy_assign_n(U* dst, U const& src, I n) noexcept // pass by reference for non-scalar types
{
    C4_ASSERT(dst != &src);
    for(I i = 0; i < n; ++i)
    {
        dst[i] = src;
    }
}

template<class U, size_t N>
C4_ALWAYS_INLINE void copy_assign(U (&dst)[N], U const (&src)[N]) noexcept
{
    copy_assign_n(dst, src, N);
}

//-----------------------------------------------------------------------------
// move-construct

template<class U> C4_ALWAYS_INLINE typename std::enable_if<std::is_trivially_move_constructible<U>::value, void>::type
move_construct(U* dst, U* src) noexcept
{
    C4_ASSERT(dst != src);
    memcpy(dst, src, sizeof(U));
}
template<class U> C4_ALWAYS_INLINE typename std::enable_if< ! std::is_trivially_move_constructible<U>::value, void>::type
move_construct(U* dst, U* src) noexcept
{
    C4_ASSERT(dst != src);
    new ((void*)dst) U(std::move(*src));
}
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if<std::is_trivially_move_constructible<U>::value, void>::type
move_construct_n(U* dst, U* src, I n) noexcept
{
    C4_ASSERT(dst != src);
    memcpy(dst, src, n * sizeof(U));
}
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if< ! std::is_trivially_move_constructible<U>::value, void>::type
move_construct_n(U* dst, U* src, I n) noexcept
{
    C4_ASSERT(dst != src);
    for(I i = 0; i < n; ++i)
    {
        new ((void*)(dst + i)) U(std::move(src[i]));
    }
}

//-----------------------------------------------------------------------------
// move-assign

template<class U> C4_ALWAYS_INLINE typename std::enable_if<std::is_trivially_move_assignable<U>::value, void>::type
move_assign(U* dst, U* src) noexcept
{
    C4_ASSERT(dst != src);
    memcpy(dst, src, sizeof(U));
}
template<class U> C4_ALWAYS_INLINE typename std::enable_if< ! std::is_trivially_move_assignable<U>::value, void>::type
move_assign(U* dst, U* src) noexcept
{
    C4_ASSERT(dst != src);
    *dst = std::move(*src);
}
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if<std::is_trivially_move_assignable<U>::value, void>::type
move_assign_n(U* dst, U* src, I n) noexcept
{
    C4_ASSERT(dst != src);
    memcpy(dst, src, n * sizeof(U));
}
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if< ! std::is_trivially_move_assignable<U>::value, void>::type
move_assign_n(U* dst, U* src, I n) noexcept
{
    C4_ASSERT(dst != src);
    for(I i = 0; i < n; ++i)
    {
        *(dst + i) = std::move(*(src + i));
    }
}

//-----------------------------------------------------------------------------
// destroy

template<class U> C4_ALWAYS_INLINE typename std::enable_if<std::is_trivially_destructible<U>::value, void>::type
destroy(U* ptr) noexcept
{
    C4_UNUSED(ptr); // nothing to do
}
template<class U> C4_ALWAYS_INLINE typename std::enable_if< ! std::is_trivially_destructible<U>::value, void>::type
destroy(U* ptr) noexcept
{
    ptr->~U();
}
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if<std::is_trivially_destructible<U>::value, void>::type
destroy_n(U* ptr, I n) noexcept
{
    C4_UNUSED(ptr);
    C4_UNUSED(n); // nothing to do
}
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if< ! std::is_trivially_destructible<U>::value, void>::type
destroy_n(U* ptr, I n) noexcept
{
    for(I i = 0; i <n; ++i)
    {
        ptr[i].~U();
    }
}

//-----------------------------------------------------------------------------

/** makes room at the beginning of buf, which has a current size of n */
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if<std::is_trivially_move_constructible<U>::value, void>::type
make_room(U *buf, I bufsz, I room) C4_NOEXCEPT_A
{
    C4_ASSERT(bufsz >= 0 && room >= 0);
    if(room >= bufsz)
    {
        memcpy (buf + room, buf, bufsz * sizeof(U));
    }
    else
    {
        memmove(buf + room, buf, bufsz * sizeof(U));
    }
}
/** makes room at the beginning of buf, which has a current size of bufsz */
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if< ! std::is_trivially_move_constructible<U>::value, void>::type
make_room(U *buf, I bufsz, I room) C4_NOEXCEPT_A
{
    C4_ASSERT(bufsz >= 0 && room >= 0);
    if(room >= bufsz)
    {
        for(I i = 0; i < bufsz; ++i)
        {
            new ((void*)(buf + (i + room))) U(std::move(buf[i]));
        }
    }
    else
    {
        for(I i = 0; i < bufsz; ++i)
        {
            I w = bufsz-1 - i; // do a backwards loop
            new ((void*)(buf + (w + room))) U(std::move(buf[w]));
        }
    }
}

/** make room to the right of pos */
template<class U, class I>
C4_ALWAYS_INLINE void make_room(U *buf, I bufsz, I currsz, I pos, I room)
{
    C4_ASSERT(pos >= 0 && pos <= currsz);
    C4_ASSERT(currsz <= bufsz);
    C4_ASSERT(room + currsz <= bufsz);
    C4_UNUSED(bufsz);
    make_room(buf + pos, currsz - pos, room);
}


/** make room to the right of pos, copying to the beginning of a different buffer */
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if<std::is_trivially_move_constructible<U>::value, void>::type
make_room(U *dst, U const* src, I srcsz, I room, I pos) C4_NOEXCEPT_A
{
    C4_ASSERT(srcsz >= 0 && room >= 0 && pos >= 0);
    C4_ASSERT(pos < srcsz || (pos == 0 && srcsz == 0));
    memcpy(dst             , src      , pos           * sizeof(U));
    memcpy(dst + room + pos, src + pos, (srcsz - pos) * sizeof(U));
}
/** make room to the right of pos, copying to the beginning of a different buffer */
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if< ! std::is_trivially_move_constructible<U>::value, void>::type
make_room(U *dst, U const* src, I srcsz, I room, I pos)
{
    C4_ASSERT(srcsz >= 0 && room >= 0 && pos >= 0);
    C4_ASSERT(pos < srcsz || (pos == 0 && srcsz == 0));
    for(I i = 0; i < pos; ++i)
    {
        new ((void*)(dst + i)) U(std::move(src[i]));
    }
    src += pos;
    dst += room + pos;
    for(I i = 0, e = srcsz - pos; i < e; ++i)
    {
        new ((void*)(dst + i)) U(std::move(src[i]));
    }
}

template<class U, class I>
C4_ALWAYS_INLINE void make_room
(
    U      * dst, I dstsz,
    U const* src, I srcsz,
    I room, I pos
)
{
    C4_ASSERT(pos >= 0 && pos < srcsz || (srcsz == 0 && pos == 0));
    C4_ASSERT(pos >= 0 && pos < dstsz || (dstsz == 0 && pos == 0));
    C4_ASSERT(srcsz+room <= dstsz);
    C4_UNUSED(dstsz);
    make_room(dst, src, srcsz, room, pos);
}


//-----------------------------------------------------------------------------
/** destroy room at the beginning of buf, which has a current size of n */
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if<std::is_scalar<U>::value || (std::is_standard_layout<U>::value && std::is_trivial<U>::value), void>::type
destroy_room(U *buf, I n, I room) C4_NOEXCEPT_A
{
    C4_ASSERT(n >= 0 && room >= 0);
    C4_ASSERT(room <= n);
    if(room < n)
    {
        memmove(buf, buf + room, (n - room) * sizeof(U));
    }
    else
    {
        // nothing to do - no need to destroy scalar types
    }
}
/** destroy room at the beginning of buf, which has a current size of n */
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if< ! (std::is_scalar<U>::value || (std::is_standard_layout<U>::value && std::is_trivial<U>::value)), void>::type
destroy_room(U *buf, I n, I room)
{
    C4_ASSERT(n >= 0 && room >= 0);
    C4_ASSERT(room <= n);
    if(room < n)
    {
        for(I i = 0, e = n - room; i < e; ++i)
        {
            buf[i] = std::move(buf[i + room]);
        }
    }
    else
    {
        for(I i = 0; i < n; ++i)
        {
            buf[i].~U();
        }
    }
}

/** destroy room to the right of pos, copying to a different buffer */
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if<std::is_trivially_move_constructible<U>::value, void>::type
destroy_room(U *dst, U const* src, I n, I room, I pos) C4_NOEXCEPT_A
{
    C4_ASSERT(n >= 0 && room >= 0 && pos >= 0);
    C4_ASSERT(pos <n);
    C4_ASSERT(pos + room <= n);
    memcpy(dst, src, pos * sizeof(U));
    memcpy(dst + pos, src + room + pos, (n - pos - room) * sizeof(U));
}
/** destroy room to the right of pos, copying to a different buffer */
template<class U, class I> C4_ALWAYS_INLINE typename std::enable_if< ! std::is_trivially_move_constructible<U>::value, void>::type
destroy_room(U *dst, U const* src, I n, I room, I pos)
{
    C4_ASSERT(n >= 0 && room >= 0 && pos >= 0);
    C4_ASSERT(pos < n);
    C4_ASSERT(pos + room <= n);
    for(I i = 0; i < pos; ++i)
    {
        new ((void*)(dst + i)) U(std::move(src[i]));
    }
    src += room + pos;
    dst += pos;
    for(I i = 0, e = n - pos - room; i < e; ++i)
    {
        new ((void*)(dst + i)) U(std::move(src[i]));
    }
}

} // namespace c4

#undef _C4REQUIRE

#endif /* _C4_CTOR_DTOR_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/ctor_dtor.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/allocator.hpp
// https://github.com/biojppm/c4core/src/c4/allocator.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_ALLOCATOR_HPP_
#define _C4_ALLOCATOR_HPP_

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/memory_resource.hpp
//#include "c4/memory_resource.hpp"
#if !defined(C4_MEMORY_RESOURCE_HPP_) && !defined(_C4_MEMORY_RESOURCE_HPP_)
#error "amalgamate: file c4/memory_resource.hpp must have been included at this point"
#endif /* C4_MEMORY_RESOURCE_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/ctor_dtor.hpp
//#include "c4/ctor_dtor.hpp"
#if !defined(C4_CTOR_DTOR_HPP_) && !defined(_C4_CTOR_DTOR_HPP_)
#error "amalgamate: file c4/ctor_dtor.hpp must have been included at this point"
#endif /* C4_CTOR_DTOR_HPP_ */


#include <memory> // std::allocator_traits
//included above:
//#include <type_traits>

/** @file allocator.hpp Contains classes to make typeful allocations (note
 * that memory resources are typeless) */

/** @defgroup mem_res_providers Memory resource providers
 * @brief Policy classes which provide a memory resource for
 * use in an allocator.
 * @ingroup memory
 */

/** @defgroup allocators Allocators
 * @brief Lightweight classes that act as handles to specific memory
 * resources and provide typeful memory.
 * @ingroup memory
 */

namespace c4 {

namespace detail {
template<class T> inline size_t size_for      (size_t num_objs) noexcept { return num_objs * sizeof(T); }
template<       > inline size_t size_for<void>(size_t num_objs) noexcept { return num_objs;             }
} // namespace detail


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** provides a per-allocator memory resource
 * @ingroup mem_res_providers */
class MemRes
{
public:

    MemRes() : m_resource(get_memory_resource()) {}
    MemRes(MemoryResource* r) noexcept : m_resource(r ? r : get_memory_resource()) {}

    inline MemoryResource* resource() const { return m_resource; }

private:

    MemoryResource* m_resource;

};


/** the allocators using this will default to the global memory resource
 * @ingroup mem_res_providers */
class MemResGlobal
{
public:

    MemResGlobal() {}
    MemResGlobal(MemoryResource* r) noexcept { C4_UNUSED(r); C4_ASSERT(r == get_memory_resource()); }

    inline MemoryResource* resource() const { return get_memory_resource(); }
};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

namespace detail {
template<class MemRes>
struct _AllocatorUtil;

template<class T, class ...Args>
struct has_no_alloc
    : public std::integral_constant<bool,
                                    !(std::uses_allocator<T, MemoryResource*>::value)
                                    && std::is_constructible<T, Args...>::value> {};

// std::uses_allocator_v<U, MemoryResource> && std::is_constructible<U, std::allocator_arg_t, MemoryResource*, Args...>
// ie can construct(std::allocator_arg_t, MemoryResource*, Args...)
template<class T, class ...Args>
struct has_alloc_arg
    : public std::integral_constant<bool,
                                    std::uses_allocator<T, MemoryResource*>::value
                                    && std::is_constructible<T, std::allocator_arg_t, MemoryResource*, Args...>::value> {};
// std::uses_allocator<U> && std::is_constructible<U, Args..., MemoryResource*>
// ie, can construct(Args..., MemoryResource*)
template<class T, class ...Args>
struct has_alloc
    : public std::integral_constant<bool,
                                    std::uses_allocator<T, MemoryResource*>::value
                                    && std::is_constructible<T, Args..., MemoryResource*>::value> {};

} // namespace detail


template<class MemRes>
struct detail::_AllocatorUtil : public MemRes
{
    using MemRes::MemRes;

    /** for construct:
     * @see http://en.cppreference.com/w/cpp/experimental/polymorphic_allocator/construct */

    // 1. types with no allocators
    template <class U, class... Args>
    C4_ALWAYS_INLINE typename std::enable_if<detail::has_no_alloc<U, Args...>::value, void>::type
    construct(U *ptr, Args &&...args)
    {
        c4::construct(ptr, std::forward<Args>(args)...);
    }
    template<class U, class I, class... Args>
    C4_ALWAYS_INLINE typename std::enable_if<detail::has_no_alloc<U, Args...>::value, void>::type
    construct_n(U* ptr, I n, Args&&... args)
    {
        c4::construct_n(ptr, n, std::forward<Args>(args)...);
    }

    // 2. types using allocators (ie, containers)

    // 2.1. can construct(std::allocator_arg_t, MemoryResource*, Args...)
    template<class U, class... Args>
    C4_ALWAYS_INLINE typename std::enable_if<detail::has_alloc_arg<U, Args...>::value, void>::type
    construct(U* ptr, Args&&... args)
    {
        c4::construct(ptr, std::allocator_arg, this->resource(), std::forward<Args>(args)...);
    }
    template<class U, class I, class... Args>
    C4_ALWAYS_INLINE typename std::enable_if<detail::has_alloc_arg<U, Args...>::value, void>::type
    construct_n(U* ptr, I n, Args&&... args)
    {
        c4::construct_n(ptr, n, std::allocator_arg, this->resource(), std::forward<Args>(args)...);
    }

    // 2.2. can construct(Args..., MemoryResource*)
    template<class U, class... Args>
    C4_ALWAYS_INLINE typename std::enable_if<detail::has_alloc<U, Args...>::value, void>::type
    construct(U* ptr, Args&&... args)
    {
        c4::construct(ptr, std::forward<Args>(args)..., this->resource());
    }
    template<class U, class I, class... Args>
    C4_ALWAYS_INLINE typename std::enable_if<detail::has_alloc<U, Args...>::value, void>::type
    construct_n(U* ptr, I n, Args&&... args)
    {
        c4::construct_n(ptr, n, std::forward<Args>(args)..., this->resource());
    }

    template<class U>
    static C4_ALWAYS_INLINE void destroy(U* ptr)
    {
        c4::destroy(ptr);
    }
    template<class U, class I>
    static C4_ALWAYS_INLINE void destroy_n(U* ptr, I n)
    {
        c4::destroy_n(ptr, n);
    }
};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** An allocator is simply a proxy to a memory resource.
 * @param T
 * @param MemResProvider
 * @ingroup allocators */
template<class T, class MemResProvider=MemResGlobal>
class Allocator : public detail::_AllocatorUtil<MemResProvider>
{
public:

    using impl_type = detail::_AllocatorUtil<MemResProvider>;

    using value_type = T;
    using pointer = T*;
    using const_pointer = T const*;
    using reference = T&;
    using const_reference = T const&;
    using size_type = size_t;
    using difference_type = std::ptrdiff_t;
    using propagate_on_container_move_assigment = std::true_type;

public:

    template<class U, class MRProv>
    bool operator== (Allocator<U, MRProv> const& that) const
    {
        return this->resource() == that.resource();
    }
    template<class U, class MRProv>
    bool operator!= (Allocator<U, MRProv> const& that) const
    {
        return this->resource() != that.resource();
    }

public:

    template<class U, class MRProv> friend class Allocator;
    template<class U>
    struct rebind
    {
        using other = Allocator<U, MemResProvider>;
    };
    template<class U>
    typename rebind<U>::other rebound()
    {
        return typename rebind<U>::other(*this);
    }

public:

    using impl_type::impl_type;
    Allocator() : impl_type() {} // VS demands this

    template<class U> Allocator(Allocator<U, MemResProvider> const& that) : impl_type(that.resource()) {}

    Allocator(Allocator const&) = default;
    Allocator(Allocator     &&) = default;

    Allocator& operator= (Allocator const&) = default; // WTF? why? @see http://en.cppreference.com/w/cpp/memory/polymorphic_allocator
    Allocator& operator= (Allocator     &&) = default;

    /** returns a default-constructed polymorphic allocator object
     * @see http://en.cppreference.com/w/cpp/memory/polymorphic_allocator/select_on_container_copy_construction      */
    Allocator select_on_container_copy_construct() const { return Allocator(*this); }

    T* allocate(size_t num_objs, size_t alignment=alignof(T))
    {
        C4_ASSERT(this->resource() != nullptr);
        C4_ASSERT(alignment >= alignof(T));
        void* vmem = this->resource()->allocate(detail::size_for<T>(num_objs), alignment);
        T* mem = static_cast<T*>(vmem);
        return mem;
    }

    void deallocate(T * ptr, size_t num_objs, size_t alignment=alignof(T))
    {
        C4_ASSERT(this->resource() != nullptr);
        C4_ASSERT(alignment>= alignof(T));
        this->resource()->deallocate(ptr, detail::size_for<T>(num_objs), alignment);
    }

    T* reallocate(T* ptr, size_t oldnum, size_t newnum, size_t alignment=alignof(T))
    {
        C4_ASSERT(this->resource() != nullptr);
        C4_ASSERT(alignment >= alignof(T));
        void* vmem = this->resource()->reallocate(ptr, detail::size_for<T>(oldnum), detail::size_for<T>(newnum), alignment);
        T* mem = static_cast<T*>(vmem);
        return mem;
    }

};

//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** @ingroup allocators */
template<class T, size_t N=16, size_t Alignment=alignof(T), class MemResProvider=MemResGlobal>
class SmallAllocator : public detail::_AllocatorUtil<MemResProvider>
{
    static_assert(Alignment >= alignof(T), "invalid alignment");

    using impl_type = detail::_AllocatorUtil<MemResProvider>;

    alignas(Alignment) char m_arr[N * sizeof(T)];
    size_t m_num{0};

public:

    using value_type = T;
    using pointer = T*;
    using const_pointer = T const*;
    using reference = T&;
    using const_reference = T const&;
    using size_type = size_t;
    using difference_type = std::ptrdiff_t;
    using propagate_on_container_move_assigment = std::true_type;

    template<class U>
    bool operator== (SmallAllocator<U,N,Alignment,MemResProvider> const&) const
    {
        return false;
    }
    template<class U>
    bool operator!= (SmallAllocator<U,N,Alignment,MemResProvider> const&) const
    {
        return true;
    }

public:

    template<class U, size_t, size_t, class> friend class SmallAllocator;
    template<class U>
    struct rebind
    {
        using other = SmallAllocator<U, N, alignof(U), MemResProvider>;
    };
    template<class U>
    typename rebind<U>::other rebound()
    {
        return typename rebind<U>::other(*this);
    }

public:

    using impl_type::impl_type;
    SmallAllocator() : impl_type() {} // VS demands this

    template<class U, size_t N2, size_t A2, class MP2>
    SmallAllocator(SmallAllocator<U,N2,A2,MP2> const& that) : impl_type(that.resource())
    {
        C4_ASSERT(that.m_num == 0);
    }

    SmallAllocator(SmallAllocator const&) = default;
    SmallAllocator(SmallAllocator     &&) = default;

    SmallAllocator& operator= (SmallAllocator const&) = default; // WTF? why? @see http://en.cppreference.com/w/cpp/memory/polymorphic_allocator
    SmallAllocator& operator= (SmallAllocator     &&) = default;

    /** returns a default-constructed polymorphic allocator object
     * @see http://en.cppreference.com/w/cpp/memory/polymorphic_allocator/select_on_container_copy_construction      */
    SmallAllocator select_on_container_copy_construct() const { return SmallAllocator(*this); }

    T* allocate(size_t num_objs, size_t alignment=Alignment)
    {
        C4_ASSERT(this->resource() != nullptr);
        C4_ASSERT(alignment >= alignof(T));
        void *vmem;
        if(m_num + num_objs <= N)
        {
            vmem = (m_arr + m_num * sizeof(T));
        }
        else
        {
            vmem = this->resource()->allocate(num_objs * sizeof(T), alignment);
        }
        m_num += num_objs;
        T *mem = static_cast<T*>(vmem);
        return mem;
    }

    void deallocate(T * ptr, size_t num_objs, size_t alignment=Alignment)
    {
        C4_ASSERT(m_num >= num_objs);
        m_num -= num_objs;
        if((char*)ptr >= m_arr && (char*)ptr < m_arr + (N * sizeof(T)))
        {
            return;
        }
        C4_ASSERT(this->resource() != nullptr);
        C4_ASSERT(alignment >= alignof(T));
        this->resource()->deallocate(ptr, num_objs * sizeof(T), alignment);
    }

    T* reallocate(T * ptr, size_t oldnum, size_t newnum, size_t alignment=Alignment)
    {
        C4_ASSERT(this->resource() != nullptr);
        C4_ASSERT(alignment >= alignof(T));
        if(oldnum <= N && newnum <= N)
        {
            return m_arr;
        }
        else if(oldnum <= N && newnum > N)
        {
            return allocate(newnum, alignment);
        }
        else if(oldnum > N && newnum <= N)
        {
            deallocate(ptr, oldnum, alignment);
            return m_arr;
        }
        void* vmem = this->resource()->reallocate(ptr, oldnum * sizeof(T), newnum * sizeof(T), alignment);
        T* mem = static_cast<T*>(vmem);
        return mem;
    }

};

//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** An allocator making use of the global memory resource.
 * @ingroup allocators */
template<class T> using allocator = Allocator<T, MemResGlobal>;
/** An allocator with a per-instance memory resource
 * @ingroup allocators */
template<class T> using allocator_mr = Allocator<T, MemRes>;

/** @ingroup allocators */
template<class T, size_t N=16, size_t Alignment=alignof(T)> using small_allocator = SmallAllocator<T, N, Alignment, MemResGlobal>;
/** @ingroup allocators */
template<class T, size_t N=16, size_t Alignment=alignof(T)> using small_allocator_mr = SmallAllocator<T, N, Alignment, MemRes>;

} // namespace c4

#endif /* _C4_ALLOCATOR_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/allocator.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/char_traits.hpp
// https://github.com/biojppm/c4core/src/c4/char_traits.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_CHAR_TRAITS_HPP_
#define _C4_CHAR_TRAITS_HPP_

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/config.hpp
//#include "c4/config.hpp"
#if !defined(C4_CONFIG_HPP_) && !defined(_C4_CONFIG_HPP_)
#error "amalgamate: file c4/config.hpp must have been included at this point"
#endif /* C4_CONFIG_HPP_ */


#include <string> // needed because of std::char_traits
#include <cctype>
#include <cwctype>

namespace c4 {

C4_ALWAYS_INLINE bool isspace(char c) { return std::isspace(c) != 0; }
C4_ALWAYS_INLINE bool isspace(wchar_t c) { return std::iswspace(static_cast<wint_t>(c)) != 0; }

//-----------------------------------------------------------------------------
template<typename C>
struct char_traits;

template<>
struct char_traits<char> : public std::char_traits<char>
{
    constexpr static const char whitespace_chars[] = " \f\n\r\t\v";
    constexpr static const size_t num_whitespace_chars = sizeof(whitespace_chars) - 1;
};

template<>
struct char_traits<wchar_t> : public std::char_traits<wchar_t>
{
    constexpr static const wchar_t whitespace_chars[] = L" \f\n\r\t\v";
    constexpr static const size_t num_whitespace_chars = sizeof(whitespace_chars) - 1;
};


//-----------------------------------------------------------------------------
namespace detail {
template<typename C>
struct needed_chars;
template<>
struct needed_chars<char>
{
    template<class SizeType>
    C4_ALWAYS_INLINE constexpr static SizeType for_bytes(SizeType num_bytes)
    {
        return num_bytes;
    }
};
template<>
struct needed_chars<wchar_t>
{
    template<class SizeType>
    C4_ALWAYS_INLINE constexpr static SizeType for_bytes(SizeType num_bytes)
    {
        // wchar_t is not necessarily 2 bytes.
        return (num_bytes / static_cast<SizeType>(sizeof(wchar_t))) + ((num_bytes & static_cast<SizeType>(SizeType(sizeof(wchar_t)) - SizeType(1))) != 0);
    }
};
} // namespace detail

/** get the number of C characters needed to store a number of bytes */
template<typename C, typename SizeType>
C4_ALWAYS_INLINE constexpr SizeType num_needed_chars(SizeType num_bytes)
{
    return detail::needed_chars<C>::for_bytes(num_bytes);
}


//-----------------------------------------------------------------------------

/** get the given text string as either char or wchar_t according to the given type */
#define C4_TXTTY(txt, type) \
    /* is there a smarter way to do this? */\
    c4::detail::literal_as<type>::get(txt, C4_WIDEN(txt))

namespace detail {
template<typename C>
struct literal_as;

template<>
struct literal_as<char>
{
    C4_ALWAYS_INLINE static constexpr const char* get(const char* str, const wchar_t *)
    {
        return str;
    }
};
template<>
struct literal_as<wchar_t>
{
    C4_ALWAYS_INLINE static constexpr const wchar_t* get(const char*, const wchar_t *wstr)
    {
        return wstr;
    }
};
} // namespace detail

} // namespace c4

#endif /* _C4_CHAR_TRAITS_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/char_traits.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/hash.hpp
// https://github.com/biojppm/c4core/src/c4/hash.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_HASH_HPP_
#define _C4_HASH_HPP_

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/config.hpp
//#include "c4/config.hpp"
#if !defined(C4_CONFIG_HPP_) && !defined(_C4_CONFIG_HPP_)
#error "amalgamate: file c4/config.hpp must have been included at this point"
#endif /* C4_CONFIG_HPP_ */

#include <climits>

/** @file hash.hpp */

/** @defgroup hash Hash utils
 * @see http://aras-p.info/blog/2016/08/02/Hash-Functions-all-the-way-down/ */

namespace c4 {

namespace detail {

/** @internal
 * @ingroup hash
 * @see this was taken a great answer in stackoverflow:
 * https://stackoverflow.com/a/34597785/5875572
 * @see http://aras-p.info/blog/2016/08/02/Hash-Functions-all-the-way-down/ */
template<typename ResultT, ResultT OffsetBasis, ResultT Prime>
class basic_fnv1a final
{

  static_assert(std::is_unsigned<ResultT>::value, "need unsigned integer");

public:

    using result_type = ResultT;

private:

    result_type state_ {};

public:

    C4_CONSTEXPR14 basic_fnv1a() noexcept : state_ {OffsetBasis} {}

    C4_CONSTEXPR14 void update(const void *const data, const size_t size) noexcept
    {
        auto cdata = static_cast<const unsigned char *>(data);
        auto acc = this->state_;
        for(size_t i = 0; i < size; ++i)
        {
            const auto next = size_t(cdata[i]);
            acc = (acc ^ next) * Prime;
        }
        this->state_ = acc;
    }

    C4_CONSTEXPR14 result_type digest() const noexcept
    {
        return this->state_;
    }

};

using fnv1a_32 = basic_fnv1a<uint32_t, UINT32_C(          2166136261), UINT32_C(     16777619)>;
using fnv1a_64 = basic_fnv1a<uint64_t, UINT64_C(14695981039346656037), UINT64_C(1099511628211)>;

template<size_t Bits> struct fnv1a;
template<> struct fnv1a<32> { using type = fnv1a_32; };
template<> struct fnv1a<64> { using type = fnv1a_64; };

} // namespace detail


/** @ingroup hash */
template<size_t Bits>
using fnv1a_t = typename detail::fnv1a<Bits>::type;


/** @ingroup hash */
C4_CONSTEXPR14 inline size_t hash_bytes(const void *const data, const size_t size) noexcept
{
    fnv1a_t<CHAR_BIT * sizeof(size_t)> fn{};
    fn.update(data, size);
    return fn.digest();
}

/**
 * @overload hash_bytes
 * @ingroup hash */
template<size_t N>
C4_CONSTEXPR14 inline size_t hash_bytes(const char (&str)[N]) noexcept
{
    fnv1a_t<CHAR_BIT * sizeof(size_t)> fn{};
    fn.update(str, N);
    return fn.digest();
}

} // namespace c4


#endif // _C4_HASH_HPP_


// (end https://github.com/biojppm/c4core/src/c4/hash.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/szconv.hpp
// https://github.com/biojppm/c4core/src/c4/szconv.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_SZCONV_HPP_
#define _C4_SZCONV_HPP_

/** @file szconv.hpp utilities to deal safely with narrowing conversions */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/config.hpp
//#include "c4/config.hpp"
#if !defined(C4_CONFIG_HPP_) && !defined(_C4_CONFIG_HPP_)
#error "amalgamate: file c4/config.hpp must have been included at this point"
#endif /* C4_CONFIG_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/error.hpp
//#include "c4/error.hpp"
#if !defined(C4_ERROR_HPP_) && !defined(_C4_ERROR_HPP_)
#error "amalgamate: file c4/error.hpp must have been included at this point"
#endif /* C4_ERROR_HPP_ */


#include <limits>

namespace c4 {

/** @todo this would be so much easier with calls to numeric_limits::max()... */
template<class SizeOut, class SizeIn>
struct is_narrower_size : std::conditional
<
   (std::is_signed<SizeOut>::value == std::is_signed<SizeIn>::value)
   ?
   (sizeof(SizeOut) < sizeof(SizeIn))
   :
   (
       (sizeof(SizeOut) < sizeof(SizeIn))
       ||
       (
           (sizeof(SizeOut) == sizeof(SizeIn))
           &&
           (std::is_signed<SizeOut>::value && std::is_unsigned<SizeIn>::value)
       )
   ),
   std::true_type,
   std::false_type
>::type
{
    static_assert(std::is_integral<SizeIn >::value, "must be integral type");
    static_assert(std::is_integral<SizeOut>::value, "must be integral type");
};


/** when SizeOut is wider than SizeIn, assignment can occur without reservations */
template<class SizeOut, class SizeIn>
C4_ALWAYS_INLINE
typename std::enable_if< ! is_narrower_size<SizeOut, SizeIn>::value, SizeOut>::type
szconv(SizeIn sz) noexcept
{
    return static_cast<SizeOut>(sz);
}

/** when SizeOut is narrower than SizeIn, narrowing will occur, so we check
 * for overflow. Note that this check is done only if C4_XASSERT is enabled.
 * @see C4_XASSERT */
template<class SizeOut, class SizeIn>
C4_ALWAYS_INLINE
typename std::enable_if<is_narrower_size<SizeOut, SizeIn>::value, SizeOut>::type
szconv(SizeIn sz) C4_NOEXCEPT_X
{
    C4_XASSERT(sz >= 0);
    C4_XASSERT_MSG((SizeIn)sz <= (SizeIn)std::numeric_limits<SizeOut>::max(), "size conversion overflow: in=%zu", (size_t)sz);
    SizeOut szo = static_cast<SizeOut>(sz);
    return szo;
}

} // namespace c4

#endif /* _C4_SZCONV_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/szconv.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/blob.hpp
// https://github.com/biojppm/c4core/src/c4/blob.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_BLOB_HPP_
#define _C4_BLOB_HPP_

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/types.hpp
//#include "c4/types.hpp"
#if !defined(C4_TYPES_HPP_) && !defined(_C4_TYPES_HPP_)
#error "amalgamate: file c4/types.hpp must have been included at this point"
#endif /* C4_TYPES_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/error.hpp
//#include "c4/error.hpp"
#if !defined(C4_ERROR_HPP_) && !defined(_C4_ERROR_HPP_)
#error "amalgamate: file c4/error.hpp must have been included at this point"
#endif /* C4_ERROR_HPP_ */


/** @file blob.hpp Mutable and immutable binary data blobs.
*/

namespace c4 {

template<class T>
struct blob_
{
    T *    buf;
    size_t len;

    C4_ALWAYS_INLINE blob_() noexcept : buf(), len() {}

    C4_ALWAYS_INLINE blob_(blob_ const& that) noexcept = default;
    C4_ALWAYS_INLINE blob_(blob_     && that) noexcept = default;
    C4_ALWAYS_INLINE blob_& operator=(blob_     && that) noexcept = default;
    C4_ALWAYS_INLINE blob_& operator=(blob_ const& that) noexcept = default;

    // need to sfinae out copy constructors! (why? isn't the above sufficient?)
    #define _C4_REQUIRE_NOT_SAME class=typename std::enable_if<( ! std::is_same<U, blob_>::value) && ( ! std::is_pointer<U>::value), T>::type
    template<class U, _C4_REQUIRE_NOT_SAME> C4_ALWAYS_INLINE blob_(U &var) noexcept : buf(reinterpret_cast<T*>(&var)), len(sizeof(U)) {}
    template<class U, _C4_REQUIRE_NOT_SAME> C4_ALWAYS_INLINE blob_& operator= (U &var) noexcept { buf = reinterpret_cast<T*>(&var); len = sizeof(U); return *this; }
    #undef _C4_REQUIRE_NOT_SAME

    template<class U, size_t N> C4_ALWAYS_INLINE blob_(U (&arr)[N]) noexcept : buf(reinterpret_cast<T*>(arr)), len(sizeof(U) * N) {}
    template<class U, size_t N> C4_ALWAYS_INLINE blob_& operator= (U (&arr)[N]) noexcept { buf = reinterpret_cast<T*>(arr); len = sizeof(U) * N; return *this; }

    template<class U>
    C4_ALWAYS_INLINE blob_(U          *ptr, size_t n) noexcept : buf(reinterpret_cast<T*>(ptr)), len(sizeof(U) * n) { C4_ASSERT(is_aligned(ptr)); }
    C4_ALWAYS_INLINE blob_(void       *ptr, size_t n) noexcept : buf(reinterpret_cast<T*>(ptr)), len(n) {}
    C4_ALWAYS_INLINE blob_(void const *ptr, size_t n) noexcept : buf(reinterpret_cast<T*>(ptr)), len(n) {}
};

/** an immutable binary blob */
using cblob = blob_<cbyte>;
/** a mutable binary blob */
using  blob = blob_< byte>;

C4_MUST_BE_TRIVIAL_COPY(blob);
C4_MUST_BE_TRIVIAL_COPY(cblob);

} // namespace c4

#endif // _C4_BLOB_HPP_


// (end https://github.com/biojppm/c4core/src/c4/blob.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/substr_fwd.hpp
// https://github.com/biojppm/c4core/src/c4/substr_fwd.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_SUBSTR_FWD_HPP_
#define _C4_SUBSTR_FWD_HPP_

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/export.hpp
//#include "c4/export.hpp"
#if !defined(C4_EXPORT_HPP_) && !defined(_C4_EXPORT_HPP_)
#error "amalgamate: file c4/export.hpp must have been included at this point"
#endif /* C4_EXPORT_HPP_ */


namespace c4 {

#ifndef DOXYGEN
template<class C> struct basic_substring;
using csubstr = C4CORE_EXPORT basic_substring<const char>;
using substr = C4CORE_EXPORT basic_substring<char>;
#endif // !DOXYGEN

} // namespace c4

#endif /* _C4_SUBSTR_FWD_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/substr_fwd.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/substr.hpp
// https://github.com/biojppm/c4core/src/c4/substr.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_SUBSTR_HPP_
#define _C4_SUBSTR_HPP_

/** @file substr.hpp read+write string views */

//included above:
//#include <string.h>
//included above:
//#include <ctype.h>
//included above:
//#include <type_traits>

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/config.hpp
//#include "c4/config.hpp"
#if !defined(C4_CONFIG_HPP_) && !defined(_C4_CONFIG_HPP_)
#error "amalgamate: file c4/config.hpp must have been included at this point"
#endif /* C4_CONFIG_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/error.hpp
//#include "c4/error.hpp"
#if !defined(C4_ERROR_HPP_) && !defined(_C4_ERROR_HPP_)
#error "amalgamate: file c4/error.hpp must have been included at this point"
#endif /* C4_ERROR_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/substr_fwd.hpp
//#include "c4/substr_fwd.hpp"
#if !defined(C4_SUBSTR_FWD_HPP_) && !defined(_C4_SUBSTR_FWD_HPP_)
#error "amalgamate: file c4/substr_fwd.hpp must have been included at this point"
#endif /* C4_SUBSTR_FWD_HPP_ */


#ifdef __clang__
#   pragma clang diagnostic push
#elif defined(__GNUC__)
#   pragma GCC diagnostic push
#   pragma GCC diagnostic ignored "-Wtype-limits" // disable warnings on size_t>=0, used heavily in assertions below. These assertions are a preparation step for providing the index type as a template parameter.
#   pragma GCC diagnostic ignored "-Wuseless-cast"
#endif


namespace c4 {


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

namespace detail {

template<typename C>
static inline void _do_reverse(C *C4_RESTRICT first, C *C4_RESTRICT last)
{
    while(last > first)
    {
        C tmp = *last;
        *last-- = *first;
        *first++ = tmp;
    }
}

} // namespace detail


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

// utility macros to deuglify SFINAE code; undefined after the class.
// https://stackoverflow.com/questions/43051882/how-to-disable-a-class-member-funrtion-for-certain-template-types
#define C4_REQUIRE_RW(ret_type) \
    template <typename U=C> \
    typename std::enable_if< ! std::is_const<U>::value, ret_type>::type
// non-const-to-const
#define C4_NC2C(ty) \
    typename std::enable_if<std::is_const<C>::value && ( ! std::is_const<ty>::value), ty>::type


/** a non-owning string-view, consisting of a character pointer
 * and a length.
 *
 * @note The pointer is explicitly restricted.
 * @note Because of a C++ limitation, there cannot coexist overloads for
 * constructing from a char[N] and a char*; the latter will always be chosen
 * by the compiler. To construct an object of this type, call to_substr() or
 * to_csubstr(). For a more detailed explanation on why the overloads cannot
 * coexist, see http://cplusplus.bordoon.com/specializeForCharacterArrays.html
 *
 * @see to_substr()
 * @see to_csubstr()
 */
template<class C>
struct C4CORE_EXPORT basic_substring
{
public:

    /** a restricted pointer to the first character of the substring */
    C * C4_RESTRICT str;
    /** the length of the substring */
    size_t          len;

public:

    /** @name Types */
    /** @{ */

    using  CC  = typename std::add_const<C>::type;     //!< CC=const char
    using NCC_ = typename std::remove_const<C>::type; //!< NCC_=non const char

    using ro_substr = basic_substring<CC>;
    using rw_substr = basic_substring<NCC_>;

    using char_type = C;
    using size_type = size_t;

    using iterator = C*;
    using const_iterator = CC*;

    enum : size_t { npos = (size_t)-1, NONE = (size_t)-1 };

    /// convert automatically to substring of const C
    operator ro_substr () const { ro_substr s(str, len); return s; }

    /** @} */

public:

    /** @name Default construction and assignment */
    /** @{ */

    constexpr basic_substring() : str(nullptr), len(0) {}

    constexpr basic_substring(basic_substring const&) = default;
    constexpr basic_substring(basic_substring     &&) = default;
    constexpr basic_substring(std::nullptr_t) : str(nullptr), len(0) {}

    basic_substring& operator= (basic_substring const&) = default;
    basic_substring& operator= (basic_substring     &&) = default;
    basic_substring& operator= (std::nullptr_t) { str = nullptr; len = 0; return *this; }

    /** @} */

public:

    /** @name Construction and assignment from characters with the same type */
    /** @{ */

    //basic_substring(C *s_) : str(s_), len(s_ ? strlen(s_) : 0) {}
    /** the overload for receiving a single C* pointer will always
     * hide the array[N] overload. So it is disabled. If you want to
     * construct a substr from a single pointer containing a C-style string,
     * you can call c4::to_substr()/c4::to_csubstr().
     * @see c4::to_substr()
     * @see c4::to_csubstr() */
    template<size_t N>
    constexpr basic_substring(C (&s_)[N]) noexcept : str(s_), len(N-1) {}
    basic_substring(C *s_, size_t len_) : str(s_), len(len_) { C4_ASSERT(str || !len_); }
    basic_substring(C *beg_, C *end_) : str(beg_), len(static_cast<size_t>(end_ - beg_)) { C4_ASSERT(end_ >= beg_); }

    //basic_substring& operator= (C *s_) { this->assign(s_); return *this; }
    template<size_t N>
    basic_substring& operator= (C (&s_)[N]) { this->assign<N>(s_); return *this; }

    //void assign(C *s_) { str = (s_); len = (s_ ? strlen(s_) : 0); }
    /** the overload for receiving a single C* pointer will always
     * hide the array[N] overload. So it is disabled. If you want to
     * construct a substr from a single pointer containing a C-style string,
     * you can call c4::to_substr()/c4::to_csubstr().
     * @see c4::to_substr()
     * @see c4::to_csubstr() */
    template<size_t N>
    void assign(C (&s_)[N]) { str = (s_); len = (N-1); }
    void assign(C *s_, size_t len_) { str = s_; len = len_; C4_ASSERT(str || !len_); }
    void assign(C *beg_, C *end_) { C4_ASSERT(end_ >= beg_); str = (beg_); len = (end_ - beg_); }

    void clear() { str = nullptr; len = 0; }

    /** @} */

public:

    /** @name Construction from non-const characters */
    /** @{ */

    // when the char type is const, allow construction and assignment from non-const chars

    /** only available when the char type is const */
    template<size_t N, class U=NCC_> explicit basic_substring(C4_NC2C(U) (&s_)[N]) { str = s_; len = N-1; }
    /** only available when the char type is const */
    template<          class U=NCC_>          basic_substring(C4_NC2C(U) *s_, size_t len_) { str = s_; len = len_; }
    /** only available when the char type is const */
    template<          class U=NCC_>          basic_substring(C4_NC2C(U) *beg_, C4_NC2C(U) *end_) { C4_ASSERT(end_ >= beg_); str = beg_; len = end_ - beg_;  }

    /** only available when the char type is const */
    template<size_t N, class U=NCC_> void assign(C4_NC2C(U) (&s_)[N]) { str = s_; len = N-1; }
    /** only available when the char type is const */
    template<          class U=NCC_> void assign(C4_NC2C(U) *s_, size_t len_) { str = s_; len = len_; }
    /** only available when the char type is const */
    template<          class U=NCC_> void assign(C4_NC2C(U) *beg_, C4_NC2C(U) *end_) { C4_ASSERT(end_ >= beg_); str = beg_; len = end_ - beg_;  }

    /** only available when the char type is const */
    template<size_t N, class U=NCC_>
    basic_substring& operator=(C4_NC2C(U) (&s_)[N]) { str = s_; len = N-1; return *this; }

    /** @} */

public:

    /** @name Standard accessor methods */
    /** @{ */

    C4_ALWAYS_INLINE C4_PURE bool   has_str()   const noexcept { return ! empty() && str[0] != C(0); }
    C4_ALWAYS_INLINE C4_PURE bool   empty()     const noexcept { return (len == 0 || str == nullptr); }
    C4_ALWAYS_INLINE C4_PURE bool   not_empty() const noexcept { return (len != 0 && str != nullptr); }
    C4_ALWAYS_INLINE C4_PURE size_t size()      const noexcept { return len; }

    C4_ALWAYS_INLINE C4_PURE iterator begin() noexcept { return str; }
    C4_ALWAYS_INLINE C4_PURE iterator end  () noexcept { return str + len; }

    C4_ALWAYS_INLINE C4_PURE const_iterator begin() const noexcept { return str; }
    C4_ALWAYS_INLINE C4_PURE const_iterator end  () const noexcept { return str + len; }

    C4_ALWAYS_INLINE C4_PURE C      * data()       noexcept { return str; }
    C4_ALWAYS_INLINE C4_PURE C const* data() const noexcept { return str; }

    C4_ALWAYS_INLINE C4_PURE C      & operator[] (size_t i)       noexcept { C4_ASSERT(i >= 0 && i < len); return str[i]; }
    C4_ALWAYS_INLINE C4_PURE C const& operator[] (size_t i) const noexcept { C4_ASSERT(i >= 0 && i < len); return str[i]; }

    C4_ALWAYS_INLINE C4_PURE C      & front()       noexcept { C4_ASSERT(len > 0 && str != nullptr); return *str; }
    C4_ALWAYS_INLINE C4_PURE C const& front() const noexcept { C4_ASSERT(len > 0 && str != nullptr); return *str; }

    C4_ALWAYS_INLINE C4_PURE C      & back()       noexcept { C4_ASSERT(len > 0 && str != nullptr); return *(str + len - 1); }
    C4_ALWAYS_INLINE C4_PURE C const& back() const noexcept { C4_ASSERT(len > 0 && str != nullptr); return *(str + len - 1); }

    /** @} */

public:

    /** @name Comparison methods */
    /** @{ */

    C4_PURE int compare(C const c) const noexcept
    {
        C4_XASSERT((str != nullptr) || len == 0);
        if(C4_LIKELY(str != nullptr && len > 0))
            return (*str != c) ? *str - c : (static_cast<int>(len) - 1);
        else
            return -1;
    }

    C4_PURE int compare(const char *C4_RESTRICT that, size_t sz) const noexcept
    {
        C4_XASSERT(that || sz  == 0);
        C4_XASSERT(str  || len == 0);
        if(C4_LIKELY(str && that))
        {
            {
                const size_t min = len < sz ? len : sz;
                for(size_t i = 0; i < min; ++i)
                    if(str[i] != that[i])
                        return str[i] < that[i] ? -1 : 1;
            }
            if(len < sz)
                return -1;
            else if(len == sz)
                return 0;
            else
                return 1;
        }
        else if(len == sz)
        {
            C4_XASSERT(len == 0 && sz == 0);
            return 0;
        }
        return len < sz ? -1 : 1;
    }

    C4_ALWAYS_INLINE C4_PURE int compare(ro_substr const that) const noexcept { return this->compare(that.str, that.len); }

    C4_ALWAYS_INLINE C4_PURE bool operator== (std::nullptr_t) const noexcept { return str == nullptr; }
    C4_ALWAYS_INLINE C4_PURE bool operator!= (std::nullptr_t) const noexcept { return str != nullptr; }

    C4_ALWAYS_INLINE C4_PURE bool operator== (C const c) const noexcept { return this->compare(c) == 0; }
    C4_ALWAYS_INLINE C4_PURE bool operator!= (C const c) const noexcept { return this->compare(c) != 0; }
    C4_ALWAYS_INLINE C4_PURE bool operator<  (C const c) const noexcept { return this->compare(c) <  0; }
    C4_ALWAYS_INLINE C4_PURE bool operator>  (C const c) const noexcept { return this->compare(c) >  0; }
    C4_ALWAYS_INLINE C4_PURE bool operator<= (C const c) const noexcept { return this->compare(c) <= 0; }
    C4_ALWAYS_INLINE C4_PURE bool operator>= (C const c) const noexcept { return this->compare(c) >= 0; }

    template<class U> C4_ALWAYS_INLINE C4_PURE bool operator== (basic_substring<U> const that) const noexcept { return this->compare(that) == 0; }
    template<class U> C4_ALWAYS_INLINE C4_PURE bool operator!= (basic_substring<U> const that) const noexcept { return this->compare(that) != 0; }
    template<class U> C4_ALWAYS_INLINE C4_PURE bool operator<  (basic_substring<U> const that) const noexcept { return this->compare(that) <  0; }
    template<class U> C4_ALWAYS_INLINE C4_PURE bool operator>  (basic_substring<U> const that) const noexcept { return this->compare(that) >  0; }
    template<class U> C4_ALWAYS_INLINE C4_PURE bool operator<= (basic_substring<U> const that) const noexcept { return this->compare(that) <= 0; }
    template<class U> C4_ALWAYS_INLINE C4_PURE bool operator>= (basic_substring<U> const that) const noexcept { return this->compare(that) >= 0; }

    template<size_t N> C4_ALWAYS_INLINE C4_PURE bool operator== (const char (&that)[N]) const noexcept { return this->compare(that, N-1) == 0; }
    template<size_t N> C4_ALWAYS_INLINE C4_PURE bool operator!= (const char (&that)[N]) const noexcept { return this->compare(that, N-1) != 0; }
    template<size_t N> C4_ALWAYS_INLINE C4_PURE bool operator<  (const char (&that)[N]) const noexcept { return this->compare(that, N-1) <  0; }
    template<size_t N> C4_ALWAYS_INLINE C4_PURE bool operator>  (const char (&that)[N]) const noexcept { return this->compare(that, N-1) >  0; }
    template<size_t N> C4_ALWAYS_INLINE C4_PURE bool operator<= (const char (&that)[N]) const noexcept { return this->compare(that, N-1) <= 0; }
    template<size_t N> C4_ALWAYS_INLINE C4_PURE bool operator>= (const char (&that)[N]) const noexcept { return this->compare(that, N-1) >= 0; }

    /** @} */

public:

    /** @name Sub-selection methods */
    /** @{ */

    /** true if *this is a substring of that (ie, from the same buffer) */
    C4_ALWAYS_INLINE C4_PURE bool is_sub(ro_substr const that) const noexcept
    {
        return that.is_super(*this);
    }

    /** true if that is a substring of *this (ie, from the same buffer) */
    C4_ALWAYS_INLINE C4_PURE bool is_super(ro_substr const that) const noexcept
    {
        if(C4_LIKELY(len > 0))
            return that.str >= str && that.str+that.len <= str+len;
        else
            return that.len == 0 && that.str == str && str != nullptr;
    }

    /** true if there is overlap of at least one element between that and *this */
    C4_ALWAYS_INLINE C4_PURE bool overlaps(ro_substr const that) const noexcept
    {
        // thanks @timwynants
        return that.str+that.len > str && that.str < str+len;
    }

public:

    /** return [first,len[ */
    C4_ALWAYS_INLINE C4_PURE basic_substring sub(size_t first) const noexcept
    {
        C4_ASSERT(first >= 0 && first <= len);
        return basic_substring(str + first, len - first);
    }

    /** return [first,first+num[. If num==npos, return [first,len[ */
    C4_ALWAYS_INLINE C4_PURE basic_substring sub(size_t first, size_t num) const noexcept
    {
        C4_ASSERT(first >= 0 && first <= len);
        C4_ASSERT((num >= 0 && num <= len) || (num == npos));
        size_t rnum = num != npos ? num : len - first;
        C4_ASSERT((first >= 0 && first + rnum <= len) || (num == 0));
        return basic_substring(str + first, rnum);
    }

    /** return [first,last[. If last==npos, return [first,len[ */
    C4_ALWAYS_INLINE C4_PURE basic_substring range(size_t first, size_t last=npos) const noexcept
    {
        C4_ASSERT(first >= 0 && first <= len);
        last = last != npos ? last : len;
        C4_ASSERT(first <= last);
        C4_ASSERT(last  >= 0 && last  <= len);
        return basic_substring(str + first, last - first);
    }

    /** return the first @p num elements: [0,num[*/
    C4_ALWAYS_INLINE C4_PURE basic_substring first(size_t num) const noexcept
    {
        C4_ASSERT(num <= len || num == npos);
        return basic_substring(str, num != npos ? num : len);
    }

    /** return the last @num elements: [len-num,len[*/
    C4_ALWAYS_INLINE C4_PURE basic_substring last(size_t num) const noexcept
    {
        C4_ASSERT(num <= len || num == npos);
        return num != npos ?
            basic_substring(str + len - num, num) :
            *this;
    }

    /** offset from the ends: return [left,len-right[ ; ie, trim a
        number of characters from the left and right. This is
        equivalent to python's negative list indices. */
    C4_ALWAYS_INLINE C4_PURE basic_substring offs(size_t left, size_t right) const noexcept
    {
        C4_ASSERT(left  >= 0 && left  <= len);
        C4_ASSERT(right >= 0 && right <= len);
        C4_ASSERT(left  <= len - right + 1);
        return basic_substring(str + left, len - right - left);
    }

    /** return [0, pos[ . Same as .first(pos), but provided for compatibility with .right_of() */
    C4_ALWAYS_INLINE C4_PURE basic_substring left_of(size_t pos) const noexcept
    {
        C4_ASSERT(pos <= len || pos == npos);
        return (pos != npos) ?
            basic_substring(str, pos) :
            *this;
    }

    /** return [0, pos+include_pos[ . Same as .first(pos+1), but provided for compatibility with .right_of() */
    C4_ALWAYS_INLINE C4_PURE basic_substring left_of(size_t pos, bool include_pos) const noexcept
    {
        C4_ASSERT(pos <= len || pos == npos);
        return (pos != npos) ?
            basic_substring(str, pos+include_pos) :
            *this;
    }

    /** return [pos+1, len[ */
    C4_ALWAYS_INLINE C4_PURE basic_substring right_of(size_t pos) const noexcept
    {
        C4_ASSERT(pos <= len || pos == npos);
        return (pos != npos) ?
            basic_substring(str + (pos + 1), len - (pos + 1)) :
            basic_substring(str + len, size_t(0));
    }

    /** return [pos+!include_pos, len[ */
    C4_ALWAYS_INLINE C4_PURE basic_substring right_of(size_t pos, bool include_pos) const noexcept
    {
        C4_ASSERT(pos <= len || pos == npos);
        return (pos != npos) ?
            basic_substring(str + (pos + !include_pos), len - (pos + !include_pos)) :
            basic_substring(str + len, size_t(0));
    }

public:

    /** given @p subs a substring of the current string, get the
     * portion of the current string to the left of it */
    C4_ALWAYS_INLINE C4_PURE basic_substring left_of(ro_substr const subs) const noexcept
    {
        C4_ASSERT(is_super(subs) || subs.empty());
        auto ssb = subs.begin();
        auto b = begin();
        auto e = end();
        if(ssb >= b && ssb <= e)
            return sub(0, static_cast<size_t>(ssb - b));
        else
            return sub(0, 0);
    }

    /** given @p subs a substring of the current string, get the
     * portion of the current string to the right of it */
    C4_ALWAYS_INLINE C4_PURE basic_substring right_of(ro_substr const subs) const noexcept
    {
        C4_ASSERT(is_super(subs) || subs.empty());
        auto sse = subs.end();
        auto b = begin();
        auto e = end();
        if(sse >= b && sse <= e)
            return sub(static_cast<size_t>(sse - b), static_cast<size_t>(e - sse));
        else
            return sub(0, 0);
    }

    /** @} */

public:

    /** @name Removing characters (trim()) / patterns (strip()) from the tips of the string */
    /** @{ */

    /** trim left */
    basic_substring triml(const C c) const
    {
        if( ! empty())
        {
            size_t pos = first_not_of(c);
            if(pos != npos)
                return sub(pos);
        }
        return sub(0, 0);
    }
    /** trim left ANY of the characters.
     * @see stripl() to remove a pattern from the left */
    basic_substring triml(ro_substr chars) const
    {
        if( ! empty())
        {
            size_t pos = first_not_of(chars);
            if(pos != npos)
                return sub(pos);
        }
        return sub(0, 0);
    }

    /** trim the character c from the right */
    basic_substring trimr(const C c) const
    {
        if( ! empty())
        {
            size_t pos = last_not_of(c, npos);
            if(pos != npos)
                return sub(0, pos+1);
        }
        return sub(0, 0);
    }
    /** trim right ANY of the characters
     * @see stripr() to remove a pattern from the right  */
    basic_substring trimr(ro_substr chars) const
    {
        if( ! empty())
        {
            size_t pos = last_not_of(chars, npos);
            if(pos != npos)
                return sub(0, pos+1);
        }
        return sub(0, 0);
    }

    /** trim the character c left and right */
    basic_substring trim(const C c) const
    {
        return triml(c).trimr(c);
    }
    /** trim left and right ANY of the characters
     * @see strip() to remove a pattern from the left and right */
    basic_substring trim(ro_substr const chars) const
    {
        return triml(chars).trimr(chars);
    }

    /** remove a pattern from the left
     * @see triml() to remove characters*/
    basic_substring stripl(ro_substr pattern) const
    {
        if( ! begins_with(pattern))
            return *this;
        return sub(pattern.len < len ? pattern.len : len);
    }

    /** remove a pattern from the right
     * @see trimr() to remove characters*/
    basic_substring stripr(ro_substr pattern) const
    {
        if( ! ends_with(pattern))
            return *this;
        return left_of(len - (pattern.len < len ? pattern.len : len));
    }

    /** @} */

public:

    /** @name Lookup methods */
    /** @{ */

    inline size_t find(const C c, size_t start_pos=0) const
    {
        return first_of(c, start_pos);
    }
    inline size_t find(ro_substr pattern, size_t start_pos=0) const
    {
        C4_ASSERT(start_pos == npos || (start_pos >= 0 && start_pos <= len));
        if(len < pattern.len) return npos;
        for(size_t i = start_pos, e = len - pattern.len + 1; i < e; ++i)
        {
            bool gotit = true;
            for(size_t j = 0; j < pattern.len; ++j)
            {
                C4_ASSERT(i + j < len);
                if(str[i + j] != pattern.str[j])
                {
                    gotit = false;
                    break;
                }
            }
            if(gotit)
            {
                return i;
            }
        }
        return npos;
    }

public:

    /** count the number of occurrences of c */
    inline size_t count(const C c, size_t pos=0) const
    {
        C4_ASSERT(pos >= 0 && pos <= len);
        size_t num = 0;
        pos = find(c, pos);
        while(pos != npos)
        {
            ++num;
            pos = find(c, pos + 1);
        }
        return num;
    }

    /** count the number of occurrences of s */
    inline size_t count(ro_substr c, size_t pos=0) const
    {
        C4_ASSERT(pos >= 0 && pos <= len);
        size_t num = 0;
        pos = find(c, pos);
        while(pos != npos)
        {
            ++num;
            pos = find(c, pos + c.len);
        }
        return num;
    }

    /** get the substr consisting of the first occurrence of @p c after @p pos, or an empty substr if none occurs */
    inline basic_substring select(const C c, size_t pos=0) const
    {
        pos = find(c, pos);
        return pos != npos ? sub(pos, 1) : basic_substring();
    }

    /** get the substr consisting of the first occurrence of @p pattern after @p pos, or an empty substr if none occurs */
    inline basic_substring select(ro_substr pattern, size_t pos=0) const
    {
        pos = find(pattern, pos);
        return pos != npos ? sub(pos, pattern.len) : basic_substring();
    }

public:

    struct first_of_any_result
    {
        size_t which;
        size_t pos;
        inline operator bool() const { return which != NONE && pos != npos; }
    };

    first_of_any_result first_of_any(ro_substr s0, ro_substr s1) const
    {
        ro_substr s[2] = {s0, s1};
        return first_of_any_iter(&s[0], &s[0] + 2);
    }

    first_of_any_result first_of_any(ro_substr s0, ro_substr s1, ro_substr s2) const
    {
        ro_substr s[3] = {s0, s1, s2};
        return first_of_any_iter(&s[0], &s[0] + 3);
    }

    first_of_any_result first_of_any(ro_substr s0, ro_substr s1, ro_substr s2, ro_substr s3) const
    {
        ro_substr s[4] = {s0, s1, s2, s3};
        return first_of_any_iter(&s[0], &s[0] + 4);
    }

    first_of_any_result first_of_any(ro_substr s0, ro_substr s1, ro_substr s2, ro_substr s3, ro_substr s4) const
    {
        ro_substr s[5] = {s0, s1, s2, s3, s4};
        return first_of_any_iter(&s[0], &s[0] + 5);
    }

    template<class It>
    first_of_any_result first_of_any_iter(It first_span, It last_span) const
    {
        for(size_t i = 0; i < len; ++i)
        {
            size_t curr = 0;
            for(It it = first_span; it != last_span; ++curr, ++it)
            {
                auto const& chars = *it;
                if((i + chars.len) > len) continue;
                bool gotit = true;
                for(size_t j = 0; j < chars.len; ++j)
                {
                    C4_ASSERT(i + j < len);
                    if(str[i + j] != chars[j])
                    {
                        gotit = false;
                        break;
                    }
                }
                if(gotit)
                {
                    return {curr, i};
                }
            }
        }
        return {NONE, npos};
    }

public:

    /** true if the first character of the string is @p c */
    bool begins_with(const C c) const
    {
        return len > 0 ? str[0] == c : false;
    }

    /** true if the first @p num characters of the string are @p c */
    bool begins_with(const C c, size_t num) const
    {
        if(len < num)
        {
            return false;
        }
        for(size_t i = 0; i < num; ++i)
        {
            if(str[i] != c)
            {
                return false;
            }
        }
        return true;
    }

    /** true if the string begins with the given @p pattern */
    bool begins_with(ro_substr pattern) const
    {
        if(len < pattern.len)
        {
            return false;
        }
        for(size_t i = 0; i < pattern.len; ++i)
        {
            if(str[i] != pattern[i])
            {
                return false;
            }
        }
        return true;
    }

    /** true if the first character of the string is any of the given @p chars */
    bool begins_with_any(ro_substr chars) const
    {
        if(len == 0)
        {
            return false;
        }
        for(size_t i = 0; i < chars.len; ++i)
        {
            if(str[0] == chars.str[i])
            {
                return true;
            }
        }
        return false;
    }

    /** true if the last character of the string is @p c */
    bool ends_with(const C c) const
    {
        return len > 0 ? str[len-1] == c : false;
    }

    /** true if the last @p num characters of the string are @p c */
    bool ends_with(const C c, size_t num) const
    {
        if(len < num)
        {
            return false;
        }
        for(size_t i = len - num; i < len; ++i)
        {
            if(str[i] != c)
            {
                return false;
            }
        }
        return true;
    }

    /** true if the string ends with the given @p pattern */
    bool ends_with(ro_substr pattern) const
    {
        if(len < pattern.len)
        {
            return false;
        }
        for(size_t i = 0, s = len-pattern.len; i < pattern.len; ++i)
        {
            if(str[s+i] != pattern[i])
            {
                return false;
            }
        }
        return true;
    }

    /** true if the last character of the string is any of the given @p chars */
    bool ends_with_any(ro_substr chars) const
    {
        if(len == 0)
        {
            return false;
        }
        for(size_t i = 0; i < chars.len; ++i)
        {
            if(str[len - 1] == chars[i])
            {
                return true;
            }
        }
        return false;
    }

public:

    /** @return the first position where c is found in the string, or npos if none is found */
    size_t first_of(const C c, size_t start=0) const
    {
        C4_ASSERT(start == npos || (start >= 0 && start <= len));
        for(size_t i = start; i < len; ++i)
        {
            if(str[i] == c)
                return i;
        }
        return npos;
    }

    /** @return the last position where c is found in the string, or npos if none is found */
    size_t last_of(const C c, size_t start=npos) const
    {
        C4_ASSERT(start == npos || (start >= 0 && start <= len));
        if(start == npos)
            start = len;
        for(size_t i = start-1; i != size_t(-1); --i)
        {
            if(str[i] == c)
                return i;
        }
        return npos;
    }

    /** @return the first position where ANY of the chars is found in the string, or npos if none is found */
    size_t first_of(ro_substr chars, size_t start=0) const
    {
        C4_ASSERT(start == npos || (start >= 0 && start <= len));
        for(size_t i = start; i < len; ++i)
        {
            for(size_t j = 0; j < chars.len; ++j)
            {
                if(str[i] == chars[j])
                    return i;
            }
        }
        return npos;
    }

    /** @return the last position where ANY of the chars is found in the string, or npos if none is found */
    size_t last_of(ro_substr chars, size_t start=npos) const
    {
        C4_ASSERT(start == npos || (start >= 0 && start <= len));
        if(start == npos)
            start = len;
        for(size_t i = start-1; i != size_t(-1); --i)
        {
            for(size_t j = 0; j < chars.len; ++j)
            {
                if(str[i] == chars[j])
                    return i;
            }
        }
        return npos;
    }

public:

    size_t first_not_of(const C c, size_t start=0) const
    {
        C4_ASSERT((start >= 0 && start <= len) || (start == len && len == 0));
        for(size_t i = start; i < len; ++i)
        {
            if(str[i] != c)
                return i;
        }
        return npos;
    }

    size_t last_not_of(const C c, size_t start=npos) const
    {
        C4_ASSERT(start == npos || (start >= 0 && start <= len));
        if(start == npos)
            start = len;
        for(size_t i = start-1; i != size_t(-1); --i)
        {
            if(str[i] != c)
                return i;
        }
        return npos;
    }

    size_t first_not_of(ro_substr chars, size_t start=0) const
    {
        C4_ASSERT((start >= 0 && start <= len) || (start == len && len == 0));
        for(size_t i = start; i < len; ++i)
        {
            bool gotit = true;
            for(size_t j = 0; j < chars.len; ++j)
            {
                if(str[i] == chars.str[j])
                {
                    gotit = false;
                    break;
                }
            }
            if(gotit)
            {
                return i;
            }
        }
        return npos;
    }

    size_t last_not_of(ro_substr chars, size_t start=npos) const
    {
        C4_ASSERT(start == npos || (start >= 0 && start <= len));
        if(start == npos)
            start = len;
        for(size_t i = start-1; i != size_t(-1); --i)
        {
            bool gotit = true;
            for(size_t j = 0; j < chars.len; ++j)
            {
                if(str[i] == chars.str[j])
                {
                    gotit = false;
                    break;
                }
            }
            if(gotit)
            {
                return i;
            }
        }
        return npos;
    }

    /** @} */

public:

    /** @name Range lookup methods */
    /** @{ */

    /** get the range delimited by an open-close pair of characters.
     * @note There must be no nested pairs.
     * @note No checks for escapes are performed. */
    basic_substring pair_range(CC open, CC close) const
    {
        size_t b = find(open);
        if(b == npos)
            return basic_substring();
        size_t e = find(close, b+1);
        if(e == npos)
            return basic_substring();
        basic_substring ret = range(b, e+1);
        C4_ASSERT(ret.sub(1).find(open) == npos);
        return ret;
    }

    /** get the range delimited by a single open-close character (eg, quotes).
     * @note The open-close character can be escaped. */
    basic_substring pair_range_esc(CC open_close, CC escape=CC('\\'))
    {
        size_t b = find(open_close);
        if(b == npos) return basic_substring();
        for(size_t i = b+1; i < len; ++i)
        {
            CC c = str[i];
            if(c == open_close)
            {
                if(str[i-1] != escape)
                {
                    return range(b, i+1);
                }
            }
        }
        return basic_substring();
    }

    /** get the range delimited by an open-close pair of characters,
     * with possibly nested occurrences. No checks for escapes are
     * performed. */
    basic_substring pair_range_nested(CC open, CC close) const
    {
        size_t b = find(open);
        if(b == npos) return basic_substring();
        size_t e, curr = b+1, count = 0;
        const char both[] = {open, close, '\0'};
        while((e = first_of(both, curr)) != npos)
        {
            if(str[e] == open)
            {
                ++count;
                curr = e+1;
            }
            else if(str[e] == close)
            {
                if(count == 0) return range(b, e+1);
                --count;
                curr = e+1;
            }
        }
        return basic_substring();
    }

    basic_substring unquoted() const
    {
        constexpr const C dq('"'), sq('\'');
        if(len >= 2 && (str[len - 2] != C('\\')) &&
           ((begins_with(sq) && ends_with(sq))
            ||
            (begins_with(dq) && ends_with(dq))))
        {
            return range(1, len -1);
        }
        return *this;
    }

    /** @} */

public:

    /** @name Number-matching query methods */
    /** @{ */

    /** @return true if the substring contents are a floating-point or integer number.
     * @note any leading or trailing whitespace will return false. */
    bool is_number() const
    {
        if(empty() || (first_non_empty_span().empty()))
            return false;
        if(first_uint_span() == *this)
            return true;
        if(first_int_span() == *this)
            return true;
        if(first_real_span() == *this)
            return true;
        return false;
    }

    /** @return true if the substring contents are a real number.
     * @note any leading or trailing whitespace will return false. */
    bool is_real() const
    {
        if(empty() || (first_non_empty_span().empty()))
            return false;
        if(first_real_span() == *this)
            return true;
        return false;
    }

    /** @return true if the substring contents are an integer number.
     * @note any leading or trailing whitespace will return false. */
    bool is_integer() const
    {
        if(empty() || (first_non_empty_span().empty()))
            return false;
        if(first_uint_span() == *this)
            return true;
        if(first_int_span() == *this)
            return true;
        return false;
    }

    /** @return true if the substring contents are an unsigned integer number.
     * @note any leading or trailing whitespace will return false. */
    bool is_unsigned_integer() const
    {
        if(empty() || (first_non_empty_span().empty()))
            return false;
        if(first_uint_span() == *this)
            return true;
        return false;
    }

    /** get the first span consisting exclusively of non-empty characters */
    basic_substring first_non_empty_span() const
    {
        constexpr const ro_substr empty_chars(" \n\r\t");
        size_t pos = first_not_of(empty_chars);
        if(pos == npos)
            return first(0);
        auto ret = sub(pos);
        pos = ret.first_of(empty_chars);
        return ret.first(pos);
    }

    /** get the first span which can be interpreted as an unsigned integer */
    basic_substring first_uint_span() const
    {
        basic_substring ne = first_non_empty_span();
        if(ne.empty())
            return ne;
        if(ne.str[0] == '-')
            return first(0);
        size_t skip_start = (ne.str[0] == '+') ? 1 : 0;
        return ne._first_integral_span(skip_start);
    }

    /** get the first span which can be interpreted as a signed integer */
    basic_substring first_int_span() const
    {
        basic_substring ne = first_non_empty_span();
        if(ne.empty())
            return ne;
        size_t skip_start = (ne.str[0] == '+' || ne.str[0] == '-') ? 1 : 0;
        return ne._first_integral_span(skip_start);
    }

    basic_substring _first_integral_span(size_t skip_start) const
    {
        C4_ASSERT(!empty());
        if(skip_start == len)
            return first(0);
        C4_ASSERT(skip_start < len);
        if(len >= skip_start + 3)
        {
            if(str[skip_start] != '0')
            {
                for(size_t i = skip_start; i < len; ++i)
                {
                    char c = str[i];
                    if(c < '0' || c > '9')
                        return i > skip_start && _is_delim_char(c) ? first(i) : first(0);
                }
            }
            else
            {
                char next = str[skip_start + 1];
                if(next == 'x' || next == 'X')
                {
                    skip_start += 2;
                    for(size_t i = skip_start; i < len; ++i)
                    {
                        const char c = str[i];
                        if( ! _is_hex_char(c))
                            return i > skip_start && _is_delim_char(c) ? first(i) : first(0);
                    }
                    return *this;
                }
                else if(next == 'b' || next == 'B')
                {
                    skip_start += 2;
                    for(size_t i = skip_start; i < len; ++i)
                    {
                        const char c = str[i];
                        if(c != '0' && c != '1')
                            return i > skip_start && _is_delim_char(c) ? first(i) : first(0);
                    }
                    return *this;
                }
                else if(next == 'o' || next == 'O')
                {
                    skip_start += 2;
                    for(size_t i = skip_start; i < len; ++i)
                    {
                        const char c = str[i];
                        if(c < '0' || c > '7')
                            return i > skip_start && _is_delim_char(c) ? first(i) : first(0);
                    }
                    return *this;
                }
            }
        }
        // must be a decimal, or it is not a an number
        for(size_t i = skip_start; i < len; ++i)
        {
            const char c = str[i];
            if(c < '0' || c > '9')
                return i > skip_start && _is_delim_char(c) ? first(i) : first(0);
        }
        return *this;
    }

    /** get the first span which can be interpreted as a real (floating-point) number */
    basic_substring first_real_span() const
    {
        basic_substring ne = first_non_empty_span();
        if(ne.empty())
            return ne;
        size_t skip_start = (ne.str[0] == '+' || ne.str[0] == '-');
        C4_ASSERT(skip_start == 0 || skip_start == 1);
        // if we have at least three digits after the leading sign, it
        // can be decimal, or hex, or bin or oct. Ex:
        // non-decimal: 0x0, 0b0, 0o0
        // decimal: 1.0, 10., 1e1, 100, inf, nan, infinity
        if(ne.len >= skip_start+3)
        {
            // if it does not have leading 0, it must be decimal, or it is not a real
            if(ne.str[skip_start] != '0')
            {
                if(ne.str[skip_start] == 'i') // is it infinity or inf?
                {
                    basic_substring word = ne._word_follows(skip_start + 1, "nfinity");
                    if(word.len)
                        return word;
                    return ne._word_follows(skip_start + 1, "nf");
                }
                else if(ne.str[skip_start] == 'n') // is it nan?
                {
                    return ne._word_follows(skip_start + 1, "an");
                }
                else // must be a decimal, or it is not a real
                {
                    return ne._first_real_span_dec(skip_start);
                }
            }
            else // starts with 0. is it 0x, 0b or 0o?
            {
                const char next = ne.str[skip_start + 1];
                // hexadecimal
                if(next == 'x' || next == 'X')
                    return ne._first_real_span_hex(skip_start + 2);
                // binary
                else if(next == 'b' || next == 'B')
                    return ne._first_real_span_bin(skip_start + 2);
                // octal
                else if(next == 'o' || next == 'O')
                    return ne._first_real_span_oct(skip_start + 2);
                // none of the above. may still be a decimal.
                else
                    return ne._first_real_span_dec(skip_start); // do not skip the 0.
            }
        }
        // less than 3 chars after the leading sign. It is either a
        // decimal or it is not a real. (cannot be any of 0x0, etc).
        return ne._first_real_span_dec(skip_start);
    }

    /** true if the character is a delimiter character *at the end* */
    static constexpr C4_ALWAYS_INLINE C4_CONST bool _is_delim_char(char c) noexcept
    {
        return c == ' ' || c == '\n'
            || c == ']' || c == ')'  || c == '}'
            || c == ',' || c == ';' || c == '\r' || c == '\t' || c == '\0';
    }

    /** true if the character is in [0-9a-fA-F] */
    static constexpr C4_ALWAYS_INLINE C4_CONST bool _is_hex_char(char c) noexcept
    {
        return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F');
    }

    C4_NO_INLINE C4_PURE basic_substring _word_follows(size_t pos, csubstr word) const noexcept
    {
        size_t posend = pos + word.len;
        if(len >= posend && sub(pos, word.len) == word)
            if(len == posend || _is_delim_char(str[posend]))
                return first(posend);
        return first(0);
    }

    // this function is declared inside the class to avoid a VS error with __declspec(dllimport)
    C4_NO_INLINE C4_PURE basic_substring _first_real_span_dec(size_t pos) const noexcept
    {
        bool intchars = false;
        bool fracchars = false;
        bool powchars;
        // integral part
        for( ; pos < len; ++pos)
        {
            const char c = str[pos];
            if(c >= '0' && c <= '9')
            {
                intchars = true;
            }
            else if(c == '.')
            {
                ++pos;
                goto fractional_part_dec;
            }
            else if(c == 'e' || c == 'E')
            {
                ++pos;
                goto power_part_dec;
            }
            else if(_is_delim_char(c))
            {
                return intchars ? first(pos) : first(0);
            }
            else
            {
                return first(0);
            }
        }
        // no . or p were found; this is either an integral number
        // or not a number at all
        return intchars ?
            *this :
            first(0);
    fractional_part_dec:
        C4_ASSERT(pos > 0);
        C4_ASSERT(str[pos - 1] == '.');
        for( ; pos < len; ++pos)
        {
            const char c = str[pos];
            if(c >= '0' && c <= '9')
            {
                fracchars = true;
            }
            else if(c == 'e' || c == 'E')
            {
                ++pos;
                goto power_part_dec;
            }
            else if(_is_delim_char(c))
            {
                return intchars || fracchars ? first(pos) : first(0);
            }
            else
            {
                return first(0);
            }
        }
        return intchars || fracchars ?
            *this :
            first(0);
    power_part_dec:
        C4_ASSERT(pos > 0);
        C4_ASSERT(str[pos - 1] == 'e' || str[pos - 1] == 'E');
        // either a + or a - is expected here, followed by more chars.
        // also, using (pos+1) in this check will cause an early
        // return when no more chars follow the sign.
        if(len <= (pos+1) || ((!intchars) && (!fracchars)))
            return first(0);
        ++pos; // this was the sign.
        // ... so the (pos+1) ensures that we enter the loop and
        // hence that there exist chars in the power part
        powchars = false;
        for( ; pos < len; ++pos)
        {
            const char c = str[pos];
            if(c >= '0' && c <= '9')
                powchars = true;
            else if(powchars && _is_delim_char(c))
                return first(pos);
            else
                return first(0);
        }
        return *this;
    }

    // this function is declared inside the class to avoid a VS error with __declspec(dllimport)
    C4_NO_INLINE C4_PURE basic_substring _first_real_span_hex(size_t pos) const noexcept
    {
        bool intchars = false;
        bool fracchars = false;
        bool powchars;
        // integral part
        for( ; pos < len; ++pos)
        {
            const char c = str[pos];
            if(_is_hex_char(c))
            {
                intchars = true;
            }
            else if(c == '.')
            {
                ++pos;
                goto fractional_part_hex;
            }
            else if(c == 'p' || c == 'P')
            {
                ++pos;
                goto power_part_hex;
            }
            else if(_is_delim_char(c))
            {
                return intchars ? first(pos) : first(0);
            }
            else
            {
                return first(0);
            }
        }
        // no . or p were found; this is either an integral number
        // or not a number at all
        return intchars ?
            *this :
            first(0);
    fractional_part_hex:
        C4_ASSERT(pos > 0);
        C4_ASSERT(str[pos - 1] == '.');
        for( ; pos < len; ++pos)
        {
            const char c = str[pos];
            if(_is_hex_char(c))
            {
                fracchars = true;
            }
            else if(c == 'p' || c == 'P')
            {
                ++pos;
                goto power_part_hex;
            }
            else if(_is_delim_char(c))
            {
                return intchars || fracchars ? first(pos) : first(0);
            }
            else
            {
                return first(0);
            }
        }
        return intchars || fracchars ?
            *this :
            first(0);
    power_part_hex:
        C4_ASSERT(pos > 0);
        C4_ASSERT(str[pos - 1] == 'p' || str[pos - 1] == 'P');
        // either a + or a - is expected here, followed by more chars.
        // also, using (pos+1) in this check will cause an early
        // return when no more chars follow the sign.
        if(len <= (pos+1) || (str[pos] != '+' && str[pos] != '-') || ((!intchars) && (!fracchars)))
            return first(0);
        ++pos; // this was the sign.
        // ... so the (pos+1) ensures that we enter the loop and
        // hence that there exist chars in the power part
        powchars = false;
        for( ; pos < len; ++pos)
        {
            const char c = str[pos];
            if(c >= '0' && c <= '9')
                powchars = true;
            else if(powchars && _is_delim_char(c))
                return first(pos);
            else
                return first(0);
        }
        return *this;
    }

    // this function is declared inside the class to avoid a VS error with __declspec(dllimport)
    C4_NO_INLINE C4_PURE basic_substring _first_real_span_bin(size_t pos) const noexcept
    {
        bool intchars = false;
        bool fracchars = false;
        bool powchars;
        // integral part
        for( ; pos < len; ++pos)
        {
            const char c = str[pos];
            if(c == '0' || c == '1')
            {
                intchars = true;
            }
            else if(c == '.')
            {
                ++pos;
                goto fractional_part_bin;
            }
            else if(c == 'p' || c == 'P')
            {
                ++pos;
                goto power_part_bin;
            }
            else if(_is_delim_char(c))
            {
                return intchars ? first(pos) : first(0);
            }
            else
            {
                return first(0);
            }
        }
        // no . or p were found; this is either an integral number
        // or not a number at all
        return intchars ?
            *this :
            first(0);
    fractional_part_bin:
        C4_ASSERT(pos > 0);
        C4_ASSERT(str[pos - 1] == '.');
        for( ; pos < len; ++pos)
        {
            const char c = str[pos];
            if(c == '0' || c == '1')
            {
                fracchars = true;
            }
            else if(c == 'p' || c == 'P')
            {
                ++pos;
                goto power_part_bin;
            }
            else if(_is_delim_char(c))
            {
                return intchars || fracchars ? first(pos) : first(0);
            }
            else
            {
                return first(0);
            }
        }
        return intchars || fracchars ?
            *this :
            first(0);
    power_part_bin:
        C4_ASSERT(pos > 0);
        C4_ASSERT(str[pos - 1] == 'p' || str[pos - 1] == 'P');
        // either a + or a - is expected here, followed by more chars.
        // also, using (pos+1) in this check will cause an early
        // return when no more chars follow the sign.
        if(len <= (pos+1) || (str[pos] != '+' && str[pos] != '-') || ((!intchars) && (!fracchars)))
            return first(0);
        ++pos; // this was the sign.
        // ... so the (pos+1) ensures that we enter the loop and
        // hence that there exist chars in the power part
        powchars = false;
        for( ; pos < len; ++pos)
        {
            const char c = str[pos];
            if(c >= '0' && c <= '9')
                powchars = true;
            else if(powchars && _is_delim_char(c))
                return first(pos);
            else
                return first(0);
        }
        return *this;
    }

    // this function is declared inside the class to avoid a VS error with __declspec(dllimport)
    C4_NO_INLINE C4_PURE basic_substring _first_real_span_oct(size_t pos) const noexcept
    {
        bool intchars = false;
        bool fracchars = false;
        bool powchars;
        // integral part
        for( ; pos < len; ++pos)
        {
            const char c = str[pos];
            if(c >= '0' && c <= '7')
            {
                intchars = true;
            }
            else if(c == '.')
            {
                ++pos;
                goto fractional_part_oct;
            }
            else if(c == 'p' || c == 'P')
            {
                ++pos;
                goto power_part_oct;
            }
            else if(_is_delim_char(c))
            {
                return intchars ? first(pos) : first(0);
            }
            else
            {
                return first(0);
            }
        }
        // no . or p were found; this is either an integral number
        // or not a number at all
        return intchars ?
            *this :
            first(0);
    fractional_part_oct:
        C4_ASSERT(pos > 0);
        C4_ASSERT(str[pos - 1] == '.');
        for( ; pos < len; ++pos)
        {
            const char c = str[pos];
            if(c >= '0' && c <= '7')
            {
                fracchars = true;
            }
            else if(c == 'p' || c == 'P')
            {
                ++pos;
                goto power_part_oct;
            }
            else if(_is_delim_char(c))
            {
                return intchars || fracchars ? first(pos) : first(0);
            }
            else
            {
                return first(0);
            }
        }
        return intchars || fracchars ?
            *this :
            first(0);
    power_part_oct:
        C4_ASSERT(pos > 0);
        C4_ASSERT(str[pos - 1] == 'p' || str[pos - 1] == 'P');
        // either a + or a - is expected here, followed by more chars.
        // also, using (pos+1) in this check will cause an early
        // return when no more chars follow the sign.
        if(len <= (pos+1) || (str[pos] != '+' && str[pos] != '-') || ((!intchars) && (!fracchars)))
            return first(0);
        ++pos; // this was the sign.
        // ... so the (pos+1) ensures that we enter the loop and
        // hence that there exist chars in the power part
        powchars = false;
        for( ; pos < len; ++pos)
        {
            const char c = str[pos];
            if(c >= '0' && c <= '9')
                powchars = true;
            else if(powchars && _is_delim_char(c))
                return first(pos);
            else
                return first(0);
        }
        return *this;
    }

    /** @} */

public:

    /** @name Splitting methods */
    /** @{ */

    /** returns true if the string has not been exhausted yet, meaning
     * it's ok to call next_split() again. When no instance of sep
     * exists in the string, returns the full string. When the input
     * is an empty string, the output string is the empty string. */
    bool next_split(C sep, size_t *C4_RESTRICT start_pos, basic_substring *C4_RESTRICT out) const
    {
        if(C4_LIKELY(*start_pos < len))
        {
            for(size_t i = *start_pos, e = len; i < e; i++)
            {
                if(str[i] == sep)
                {
                    out->assign(str + *start_pos, i - *start_pos);
                    *start_pos = i+1;
                    return true;
                }
            }
            out->assign(str + *start_pos, len - *start_pos);
            *start_pos = len + 1;
            return true;
        }
        else
        {
            bool valid = len > 0 && (*start_pos == len);
            if(valid && !empty() && str[len-1] == sep)
            {
                out->assign(str + len, (size_t)0); // the cast is needed to prevent overload ambiguity
            }
            else
            {
                out->assign(str + len + 1, (size_t)0); // the cast is needed to prevent overload ambiguity
            }
            *start_pos = len + 1;
            return valid;
        }
    }

private:

    struct split_proxy_impl
    {
        struct split_iterator_impl
        {
            split_proxy_impl const* m_proxy;
            basic_substring m_str;
            size_t m_pos;
            NCC_ m_sep;

            split_iterator_impl(split_proxy_impl const* proxy, size_t pos, C sep)
                : m_proxy(proxy), m_pos(pos), m_sep(sep)
            {
                _tick();
            }

            void _tick()
            {
                m_proxy->m_str.next_split(m_sep, &m_pos, &m_str);
            }

            split_iterator_impl& operator++ () { _tick(); return *this; }
            split_iterator_impl  operator++ (int) { split_iterator_impl it = *this; _tick(); return it; }

            basic_substring& operator*  () { return  m_str; }
            basic_substring* operator-> () { return &m_str; }

            bool operator!= (split_iterator_impl const& that) const
            {
                return !(this->operator==(that));
            }
            bool operator== (split_iterator_impl const& that) const
            {
                C4_XASSERT((m_sep == that.m_sep) && "cannot compare split iterators with different separators");
                if(m_str.size() != that.m_str.size())
                    return false;
                if(m_str.data() != that.m_str.data())
                    return false;
                return m_pos == that.m_pos;
            }
        };

        basic_substring m_str;
        size_t m_start_pos;
        C m_sep;

        split_proxy_impl(basic_substring str_, size_t start_pos, C sep)
            : m_str(str_), m_start_pos(start_pos), m_sep(sep)
        {
        }

        split_iterator_impl begin() const
        {
            auto it = split_iterator_impl(this, m_start_pos, m_sep);
            return it;
        }
        split_iterator_impl end() const
        {
            size_t pos = m_str.size() + 1;
            auto it = split_iterator_impl(this, pos, m_sep);
            return it;
        }
    };

public:

    using split_proxy = split_proxy_impl;

    /** a view into the splits */
    split_proxy split(C sep, size_t start_pos=0) const
    {
        C4_XASSERT((start_pos >= 0 && start_pos < len) || empty());
        auto ss = sub(0, len);
        auto it = split_proxy(ss, start_pos, sep);
        return it;
    }

public:

    /** pop right: return the first split from the right. Use
     * gpop_left() to get the reciprocal part.
     */
    basic_substring pop_right(C sep=C('/'), bool skip_empty=false) const
    {
        if(C4_LIKELY(len > 1))
        {
            auto pos = last_of(sep);
            if(pos != npos)
            {
                if(pos + 1 < len) // does not end with sep
                {
                    return sub(pos + 1); // return from sep to end
                }
                else // the string ends with sep
                {
                    if( ! skip_empty)
                    {
                        return sub(pos + 1, 0);
                    }
                    auto ppos = last_not_of(sep); // skip repeated seps
                    if(ppos == npos) // the string is all made of seps
                    {
                        return sub(0, 0);
                    }
                    // find the previous sep
                    auto pos0 = last_of(sep, ppos);
                    if(pos0 == npos) // only the last sep exists
                    {
                        return sub(0); // return the full string (because skip_empty is true)
                    }
                    ++pos0;
                    return sub(pos0);
                }
            }
            else // no sep was found, return the full string
            {
                return *this;
            }
        }
        else if(len == 1)
        {
            if(begins_with(sep))
            {
                return sub(0, 0);
            }
            return *this;
        }
        else // an empty string
        {
            return basic_substring();
        }
    }

    /** return the first split from the left. Use gpop_right() to get
     * the reciprocal part. */
    basic_substring pop_left(C sep = C('/'), bool skip_empty=false) const
    {
        if(C4_LIKELY(len > 1))
        {
            auto pos = first_of(sep);
            if(pos != npos)
            {
                if(pos > 0)  // does not start with sep
                {
                    return sub(0, pos); //  return everything up to it
                }
                else  // the string starts with sep
                {
                    if( ! skip_empty)
                    {
                        return sub(0, 0);
                    }
                    auto ppos = first_not_of(sep); // skip repeated seps
                    if(ppos == npos) // the string is all made of seps
                    {
                        return sub(0, 0);
                    }
                    // find the next sep
                    auto pos0 = first_of(sep, ppos);
                    if(pos0 == npos) // only the first sep exists
                    {
                        return sub(0); // return the full string (because skip_empty is true)
                    }
                    C4_XASSERT(pos0 > 0);
                    // return everything up to the second sep
                    return sub(0, pos0);
                }
            }
            else // no sep was found, return the full string
            {
                return sub(0);
            }
        }
        else if(len == 1)
        {
            if(begins_with(sep))
            {
                return sub(0, 0);
            }
            return sub(0);
        }
        else // an empty string
        {
            return basic_substring();
        }
    }

public:

    /** greedy pop left. eg, csubstr("a/b/c").gpop_left('/')="c" */
    basic_substring gpop_left(C sep = C('/'), bool skip_empty=false) const
    {
        auto ss = pop_right(sep, skip_empty);
        ss = left_of(ss);
        if(ss.find(sep) != npos)
        {
            if(ss.ends_with(sep))
            {
                if(skip_empty)
                {
                    ss = ss.trimr(sep);
                }
                else
                {
                    ss = ss.sub(0, ss.len-1); // safe to subtract because ends_with(sep) is true
                }
            }
        }
        return ss;
    }

    /** greedy pop right. eg, csubstr("a/b/c").gpop_right('/')="a" */
    basic_substring gpop_right(C sep = C('/'), bool skip_empty=false) const
    {
        auto ss = pop_left(sep, skip_empty);
        ss = right_of(ss);
        if(ss.find(sep) != npos)
        {
            if(ss.begins_with(sep))
            {
                if(skip_empty)
                {
                    ss = ss.triml(sep);
                }
                else
                {
                    ss = ss.sub(1);
                }
            }
        }
        return ss;
    }

    /** @} */

public:

    /** @name Path-like manipulation methods */
    /** @{ */

    basic_substring basename(C sep=C('/')) const
    {
        auto ss = pop_right(sep, /*skip_empty*/true);
        ss = ss.trimr(sep);
        return ss;
    }

    basic_substring dirname(C sep=C('/')) const
    {
        auto ss = basename(sep);
        ss = ss.empty() ? *this : left_of(ss);
        return ss;
    }

    C4_ALWAYS_INLINE basic_substring name_wo_extshort() const
    {
        return gpop_left('.');
    }

    C4_ALWAYS_INLINE basic_substring name_wo_extlong() const
    {
        return pop_left('.');
    }

    C4_ALWAYS_INLINE basic_substring extshort() const
    {
        return pop_right('.');
    }

    C4_ALWAYS_INLINE basic_substring extlong() const
    {
        return gpop_right('.');
    }

    /** @} */

public:

    /** @name Content-modification methods (only for non-const C) */
    /** @{ */

    /** convert the string to upper-case
     * @note this method requires that the string memory is writeable and is SFINAEd out for const C */
    C4_REQUIRE_RW(void) toupper()
    {
        for(size_t i = 0; i < len; ++i)
        {
            str[i] = static_cast<C>(::toupper(str[i]));
        }
    }

    /** convert the string to lower-case
     * @note this method requires that the string memory is writeable and is SFINAEd out for const C */
    C4_REQUIRE_RW(void) tolower()
    {
        for(size_t i = 0; i < len; ++i)
        {
            str[i] = static_cast<C>(::tolower(str[i]));
        }
    }

public:

    /** fill the entire contents with the given @p val
     * @note this method requires that the string memory is writeable and is SFINAEd out for const C */
    C4_REQUIRE_RW(void) fill(C val)
    {
        for(size_t i = 0; i < len; ++i)
        {
            str[i] = val;
        }
    }

public:

    /** set the current substring to a copy of the given csubstr
     * @note this method requires that the string memory is writeable and is SFINAEd out for const C */
    C4_REQUIRE_RW(void) copy_from(ro_substr that, size_t ifirst=0, size_t num=npos)
    {
        C4_ASSERT(ifirst >= 0 && ifirst <= len);
        num = num != npos ? num : len - ifirst;
        num = num < that.len ? num : that.len;
        C4_ASSERT(ifirst + num >= 0 && ifirst + num <= len);
        // calling memcpy with null strings is undefined behavior
        // and will wreak havoc in calling code's branches.
        // see https://github.com/biojppm/rapidyaml/pull/264#issuecomment-1262133637
        if(num)
            memcpy(str + sizeof(C) * ifirst, that.str, sizeof(C) * num);
    }

public:

    /** reverse in place
     * @note this method requires that the string memory is writeable and is SFINAEd out for const C */
    C4_REQUIRE_RW(void) reverse()
    {
        if(len == 0) return;
        detail::_do_reverse(str, str + len - 1);
    }

    /** revert a subpart in place
     * @note this method requires that the string memory is writeable and is SFINAEd out for const C */
    C4_REQUIRE_RW(void) reverse_sub(size_t ifirst, size_t num)
    {
        C4_ASSERT(ifirst >= 0 && ifirst <= len);
        C4_ASSERT(ifirst + num >= 0 && ifirst + num <= len);
        if(num == 0) return;
        detail::_do_reverse(str + ifirst, str + ifirst + num - 1);
    }

    /** revert a range in place
     * @note this method requires that the string memory is writeable and is SFINAEd out for const C */
    C4_REQUIRE_RW(void) reverse_range(size_t ifirst, size_t ilast)
    {
        C4_ASSERT(ifirst >= 0 && ifirst <= len);
        C4_ASSERT(ilast  >= 0 && ilast  <= len);
        if(ifirst == ilast) return;
        detail::_do_reverse(str + ifirst, str + ilast - 1);
    }

public:

    /** erase part of the string. eg, with char s[] = "0123456789",
     * substr(s).erase(3, 2) = "01256789", and s is now "01245678989"
     * @note this method requires that the string memory is writeable and is SFINAEd out for const C */
    C4_REQUIRE_RW(basic_substring) erase(size_t pos, size_t num)
    {
        C4_ASSERT(pos >= 0 && pos+num <= len);
        size_t num_to_move = len - pos - num;
        memmove(str + pos, str + pos + num, sizeof(C) * num_to_move);
        return basic_substring{str, len - num};
    }

    /** @note this method requires that the string memory is writeable and is SFINAEd out for const C */
    C4_REQUIRE_RW(basic_substring) erase_range(size_t first, size_t last)
    {
        C4_ASSERT(first <= last);
        return erase(first, static_cast<size_t>(last-first));
    }

    /** erase a part of the string.
     * @note @p sub must be a substring of this string
     * @note this method requires that the string memory is writeable and is SFINAEd out for const C */
    C4_REQUIRE_RW(basic_substring) erase(ro_substr sub)
    {
        C4_ASSERT(is_super(sub));
        C4_ASSERT(sub.str >= str);
        return erase(static_cast<size_t>(sub.str - str), sub.len);
    }

public:

    /** replace every occurrence of character @p value with the character @p repl
     * @return the number of characters that were replaced
     * @note this method requires that the string memory is writeable and is SFINAEd out for const C */
    C4_REQUIRE_RW(size_t) replace(C value, C repl, size_t pos=0)
    {
        C4_ASSERT((pos >= 0 && pos <= len) || pos == npos);
        size_t did_it = 0;
        while((pos = find(value, pos)) != npos)
        {
            str[pos++] = repl;
            ++did_it;
        }
        return did_it;
    }

    /** replace every occurrence of each character in @p value with
     * the character @p repl.
     * @return the number of characters that were replaced
     * @note this method requires that the string memory is writeable and is SFINAEd out for const C */
    C4_REQUIRE_RW(size_t) replace(ro_substr chars, C repl, size_t pos=0)
    {
        C4_ASSERT((pos >= 0 && pos <= len) || pos == npos);
        size_t did_it = 0;
        while((pos = first_of(chars, pos)) != npos)
        {
            str[pos++] = repl;
            ++did_it;
        }
        return did_it;
    }

    /** replace @p pattern with @p repl, and write the result into
     * @dst. pattern and repl don't need equal sizes.
     *
     * @return the required size for dst. No overflow occurs if
     * dst.len is smaller than the required size; this can be used to
     * determine the required size for an existing container. */
    size_t replace_all(rw_substr dst, ro_substr pattern, ro_substr repl, size_t pos=0) const
    {
        C4_ASSERT( ! pattern.empty()); //!< @todo relax this precondition
        C4_ASSERT( ! this  ->overlaps(dst)); //!< @todo relax this precondition
        C4_ASSERT( ! pattern.overlaps(dst));
        C4_ASSERT( ! repl   .overlaps(dst));
        C4_ASSERT((pos >= 0 && pos <= len) || pos == npos);
        C4_SUPPRESS_WARNING_GCC_PUSH
        C4_SUPPRESS_WARNING_GCC("-Warray-bounds")  // gcc11 has a false positive here
        #if (!defined(__clang__)) && (defined(__GNUC__) && (__GNUC__ >= 7))
        C4_SUPPRESS_WARNING_GCC("-Wstringop-overflow")  // gcc11 has a false positive here
        #endif
        #define _c4append(first, last)                                  \
            {                                                           \
                C4_ASSERT((last) >= (first));                           \
                size_t num = static_cast<size_t>((last) - (first));     \
                if(num > 0 && sz + num <= dst.len)                      \
                {                                                       \
                    memcpy(dst.str + sz, first, num * sizeof(C));       \
                }                                                       \
                sz += num;                                              \
            }
        size_t sz = 0;
        size_t b = pos;
        _c4append(str, str + pos);
        do {
            size_t e = find(pattern, b);
            if(e == npos)
            {
                _c4append(str + b, str + len);
                break;
            }
            _c4append(str + b, str + e);
            _c4append(repl.begin(), repl.end());
            b = e + pattern.size();
        } while(b < len && b != npos);
        return sz;
        #undef _c4append
        C4_SUPPRESS_WARNING_GCC_POP
    }

    /** @} */

}; // template class basic_substring


#undef C4_REQUIRE_RW
#undef C4_REQUIRE_RO
#undef C4_NC2C


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** Because of a C++ limitation, substr cannot provide simultaneous
 * overloads for constructing from a char[N] and a char*; the latter
 * will always be chosen by the compiler. So this specialization is
 * provided to simplify obtaining a substr from a char*. Being a
 * function has the advantage of highlighting the strlen() cost.
 *
 * @see to_csubstr
 * @see For a more detailed explanation on why the overloads cannot
 * coexist, see http://cplusplus.bordoon.com/specializeForCharacterArrays.html */
inline substr to_substr(char *s)
{
    return substr(s, s ? strlen(s) : 0);
}

/** Because of a C++ limitation, substr cannot provide simultaneous
 * overloads for constructing from a char[N] and a char*; the latter
 * will always be chosen by the compiler. So this specialization is
 * provided to simplify obtaining a substr from a char*. Being a
 * function has the advantage of highlighting the strlen() cost.
 *
 * @see to_substr
 * @see For a more detailed explanation on why the overloads cannot
 * coexist, see http://cplusplus.bordoon.com/specializeForCharacterArrays.html */
inline csubstr to_csubstr(char *s)
{
    return csubstr(s, s ? strlen(s) : 0);
}

/** Because of a C++ limitation, substr cannot provide simultaneous
 * overloads for constructing from a const char[N] and a const char*;
 * the latter will always be chosen by the compiler. So this
 * specialization is provided to simplify obtaining a substr from a
 * char*. Being a function has the advantage of highlighting the
 * strlen() cost.
 *
 * @overload to_csubstr
 * @see to_substr
 * @see For a more detailed explanation on why the overloads cannot
 * coexist, see http://cplusplus.bordoon.com/specializeForCharacterArrays.html */
inline csubstr to_csubstr(const char *s)
{
    return csubstr(s, s ? strlen(s) : 0);
}


/** neutral version for use in generic code */
inline csubstr to_csubstr(csubstr s)
{
    return s;
}

/** neutral version for use in generic code */
inline csubstr to_csubstr(substr s)
{
    return s;
}

/** neutral version for use in generic code */
inline substr to_substr(substr s)
{
    return s;
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

template<typename C, size_t N> inline bool operator== (const C (&s)[N], basic_substring<C> const that) { return that.compare(s) == 0; }
template<typename C, size_t N> inline bool operator!= (const C (&s)[N], basic_substring<C> const that) { return that.compare(s) != 0; }
template<typename C, size_t N> inline bool operator<  (const C (&s)[N], basic_substring<C> const that) { return that.compare(s) >  0; }
template<typename C, size_t N> inline bool operator>  (const C (&s)[N], basic_substring<C> const that) { return that.compare(s) <  0; }
template<typename C, size_t N> inline bool operator<= (const C (&s)[N], basic_substring<C> const that) { return that.compare(s) >= 0; }
template<typename C, size_t N> inline bool operator>= (const C (&s)[N], basic_substring<C> const that) { return that.compare(s) <= 0; }

template<typename C> inline bool operator== (C const c, basic_substring<C> const that) { return that.compare(c) == 0; }
template<typename C> inline bool operator!= (C const c, basic_substring<C> const that) { return that.compare(c) != 0; }
template<typename C> inline bool operator<  (C const c, basic_substring<C> const that) { return that.compare(c) >  0; }
template<typename C> inline bool operator>  (C const c, basic_substring<C> const that) { return that.compare(c) <  0; }
template<typename C> inline bool operator<= (C const c, basic_substring<C> const that) { return that.compare(c) >= 0; }
template<typename C> inline bool operator>= (C const c, basic_substring<C> const that) { return that.compare(c) <= 0; }


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** @define C4_SUBSTR_NO_OSTREAM_LSHIFT doctest does not deal well with
 * template operator<<
 * @see https://github.com/onqtam/doctest/pull/431 */
#ifndef C4_SUBSTR_NO_OSTREAM_LSHIFT
#ifdef __clang__
#   pragma clang diagnostic push
#   pragma clang diagnostic ignored "-Wsign-conversion"
#elif defined(__GNUC__)
#   pragma GCC diagnostic push
#   pragma GCC diagnostic ignored "-Wsign-conversion"
#endif

/** output the string to a stream */
template<class OStream, class C>
inline OStream& operator<< (OStream& os, basic_substring<C> s)
{
    os.write(s.str, s.len);
    return os;
}

// this causes ambiguity
///** this is used by google test */
//template<class OStream, class C>
//inline void PrintTo(basic_substring<C> s, OStream* os)
//{
//    os->write(s.str, s.len);
//}

#ifdef __clang__
#   pragma clang diagnostic pop
#elif defined(__GNUC__)
#   pragma GCC diagnostic pop
#endif
#endif // !C4_SUBSTR_NO_OSTREAM_LSHIFT

} // namespace c4


#ifdef __clang__
#   pragma clang diagnostic pop
#elif defined(__GNUC__)
#   pragma GCC diagnostic pop
#endif

#endif /* _C4_SUBSTR_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/substr.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/ext/fast_float.hpp
// https://github.com/biojppm/c4core/src/c4/ext/fast_float.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_EXT_FAST_FLOAT_HPP_
#define _C4_EXT_FAST_FLOAT_HPP_

#ifdef _MSC_VER
#   pragma warning(push)
#   pragma warning(disable: 4996) // snprintf/scanf: this function or variable may be unsafe
#elif defined(__clang__) || defined(__APPLE_CC__) || defined(_LIBCPP_VERSION)
#   pragma clang diagnostic push
#   if (defined(__clang_major__) && _clang_major__ >= 9) || defined(__APPLE_CC__)
#       pragma clang diagnostic ignored "-Wfortify-source"
#   endif
#   pragma clang diagnostic ignored "-Wshift-count-overflow"
#elif defined(__GNUC__)
#   pragma GCC diagnostic push
#   pragma GCC diagnostic ignored "-Wuseless-cast"
#endif

// fast_float by Daniel Lemire
// fast_float by João Paulo Magalhaes


// with contributions from Eugene Golushkov
// with contributions from Maksim Kita
// with contributions from Marcin Wojdyr
// with contributions from Neal Richardson
// with contributions from Tim Paine
// with contributions from Fabio Pellacini


// Permission is hereby granted, free of charge, to any
// person obtaining a copy of this software and associated
// documentation files (the "Software"), to deal in the
// Software without restriction, including without
// limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software
// is furnished to do so, subject to the following
// conditions:
//
// The above copyright notice and this permission notice
// shall be included in all copies or substantial portions
// of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
// ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
// TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
// PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
// SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
// IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.


#ifndef FASTFLOAT_FAST_FLOAT_H
#define FASTFLOAT_FAST_FLOAT_H

#include <system_error>

namespace fast_float {
enum chars_format {
    scientific = 1<<0,
    fixed = 1<<2,
    hex = 1<<3,
    general = fixed | scientific
};


struct from_chars_result {
  const char *ptr;
  std::errc ec;
};

struct parse_options {
  constexpr explicit parse_options(chars_format fmt = chars_format::general,
                         char dot = '.')
    : format(fmt), decimal_point(dot) {}

  /** Which number formats are accepted */
  chars_format format;
  /** The character used as decimal point */
  char decimal_point;
};

/**
 * This function parses the character sequence [first,last) for a number. It parses floating-point numbers expecting
 * a locale-indepent format equivalent to what is used by std::strtod in the default ("C") locale.
 * The resulting floating-point value is the closest floating-point values (using either float or double),
 * using the "round to even" convention for values that would otherwise fall right in-between two values.
 * That is, we provide exact parsing according to the IEEE standard.
 *
 * Given a successful parse, the pointer (`ptr`) in the returned value is set to point right after the
 * parsed number, and the `value` referenced is set to the parsed value. In case of error, the returned
 * `ec` contains a representative error, otherwise the default (`std::errc()`) value is stored.
 *
 * The implementation does not throw and does not allocate memory (e.g., with `new` or `malloc`).
 *
 * Like the C++17 standard, the `fast_float::from_chars` functions take an optional last argument of
 * the type `fast_float::chars_format`. It is a bitset value: we check whether
 * `fmt & fast_float::chars_format::fixed` and `fmt & fast_float::chars_format::scientific` are set
 * to determine whether we allowe the fixed point and scientific notation respectively.
 * The default is  `fast_float::chars_format::general` which allows both `fixed` and `scientific`.
 */
template<typename T>
from_chars_result from_chars(const char *first, const char *last,
                             T &value, chars_format fmt = chars_format::general)  noexcept;

/**
 * Like from_chars, but accepts an `options` argument to govern number parsing.
 */
template<typename T>
from_chars_result from_chars_advanced(const char *first, const char *last,
                                      T &value, parse_options options)  noexcept;

}
#endif // FASTFLOAT_FAST_FLOAT_H


#ifndef FASTFLOAT_FLOAT_COMMON_H
#define FASTFLOAT_FLOAT_COMMON_H

#include <cfloat>
//included above:
//#include <cstdint>
#include <cassert>
//included above:
//#include <cstring>

#if (defined(__x86_64) || defined(__x86_64__) || defined(_M_X64)   \
       || defined(__amd64) || defined(__aarch64__) || defined(_M_ARM64) \
       || defined(__MINGW64__)                                          \
       || defined(__s390x__)                                            \
       || (defined(__ppc64__) || defined(__PPC64__) || defined(__ppc64le__) || defined(__PPC64LE__)) \
       || defined(__EMSCRIPTEN__))
#define FASTFLOAT_64BIT
#elif (defined(__i386) || defined(__i386__) || defined(_M_IX86)   \
     || defined(__arm__) || defined(_M_ARM)                   \
     || defined(__MINGW32__))
#define FASTFLOAT_32BIT
#else
  // Need to check incrementally, since SIZE_MAX is a size_t, avoid overflow.
  // We can never tell the register width, but the SIZE_MAX is a good approximation.
  // UINTPTR_MAX and INTPTR_MAX are optional, so avoid them for max portability.
  #if SIZE_MAX == 0xffff
    #error Unknown platform (16-bit, unsupported)
  #elif SIZE_MAX == 0xffffffff
    #define FASTFLOAT_32BIT
  #elif SIZE_MAX == 0xffffffffffffffff
    #define FASTFLOAT_64BIT
  #else
    #error Unknown platform (not 32-bit, not 64-bit?)
  #endif
#endif

#if ((defined(_WIN32) || defined(_WIN64)) && !defined(__clang__))
//included above:
//#include <intrin.h>
#endif

#if defined(_MSC_VER) && !defined(__clang__)
#define FASTFLOAT_VISUAL_STUDIO 1
#endif

#ifdef _WIN32
#define FASTFLOAT_IS_BIG_ENDIAN 0
#else
#if defined(__APPLE__) || defined(__FreeBSD__)
#include <machine/endian.h>
#elif defined(sun) || defined(__sun)
#include <sys/byteorder.h>
#else
#include <endian.h>
#endif
#
#ifndef __BYTE_ORDER__
// safe choice
#define FASTFLOAT_IS_BIG_ENDIAN 0
#endif
#
#ifndef __ORDER_LITTLE_ENDIAN__
// safe choice
#define FASTFLOAT_IS_BIG_ENDIAN 0
#endif
#
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#define FASTFLOAT_IS_BIG_ENDIAN 0
#else
#define FASTFLOAT_IS_BIG_ENDIAN 1
#endif
#endif

#ifdef FASTFLOAT_VISUAL_STUDIO
#define fastfloat_really_inline __forceinline
#else
#define fastfloat_really_inline inline __attribute__((always_inline))
#endif

#ifndef FASTFLOAT_ASSERT
#define FASTFLOAT_ASSERT(x)  { if (!(x)) abort(); }
#endif

#ifndef FASTFLOAT_DEBUG_ASSERT
//included above:
//#include <cassert>
#define FASTFLOAT_DEBUG_ASSERT(x) assert(x)
#endif

// rust style `try!()` macro, or `?` operator
#define FASTFLOAT_TRY(x) { if (!(x)) return false; }

namespace fast_float {

// Compares two ASCII strings in a case insensitive manner.
inline bool fastfloat_strncasecmp(const char *input1, const char *input2,
                                  size_t length) {
  char running_diff{0};
  for (size_t i = 0; i < length; i++) {
    running_diff |= (input1[i] ^ input2[i]);
  }
  return (running_diff == 0) || (running_diff == 32);
}

#ifndef FLT_EVAL_METHOD
#error "FLT_EVAL_METHOD should be defined, please include cfloat."
#endif

// a pointer and a length to a contiguous block of memory
template <typename T>
struct span {
  const T* ptr;
  size_t length;
  span(const T* _ptr, size_t _length) : ptr(_ptr), length(_length) {}
  span() : ptr(nullptr), length(0) {}

  constexpr size_t len() const noexcept {
    return length;
  }

  const T& operator[](size_t index) const noexcept {
    FASTFLOAT_DEBUG_ASSERT(index < length);
    return ptr[index];
  }
};

struct value128 {
  uint64_t low;
  uint64_t high;
  value128(uint64_t _low, uint64_t _high) : low(_low), high(_high) {}
  value128() : low(0), high(0) {}
};

/* result might be undefined when input_num is zero */
fastfloat_really_inline int leading_zeroes(uint64_t input_num) {
  assert(input_num > 0);
#ifdef FASTFLOAT_VISUAL_STUDIO
  #if defined(_M_X64) || defined(_M_ARM64)
  unsigned long leading_zero = 0;
  // Search the mask data from most significant bit (MSB)
  // to least significant bit (LSB) for a set bit (1).
  _BitScanReverse64(&leading_zero, input_num);
  return (int)(63 - leading_zero);
  #else
  int last_bit = 0;
  if(input_num & uint64_t(0xffffffff00000000)) input_num >>= 32, last_bit |= 32;
  if(input_num & uint64_t(        0xffff0000)) input_num >>= 16, last_bit |= 16;
  if(input_num & uint64_t(            0xff00)) input_num >>=  8, last_bit |=  8;
  if(input_num & uint64_t(              0xf0)) input_num >>=  4, last_bit |=  4;
  if(input_num & uint64_t(               0xc)) input_num >>=  2, last_bit |=  2;
  if(input_num & uint64_t(               0x2)) input_num >>=  1, last_bit |=  1;
  return 63 - last_bit;
  #endif
#else
  return __builtin_clzll(input_num);
#endif
}

#ifdef FASTFLOAT_32BIT

// slow emulation routine for 32-bit
fastfloat_really_inline uint64_t emulu(uint32_t x, uint32_t y) {
    return x * (uint64_t)y;
}

// slow emulation routine for 32-bit
#if !defined(__MINGW64__)
fastfloat_really_inline uint64_t _umul128(uint64_t ab, uint64_t cd,
                                          uint64_t *hi) {
  uint64_t ad = emulu((uint32_t)(ab >> 32), (uint32_t)cd);
  uint64_t bd = emulu((uint32_t)ab, (uint32_t)cd);
  uint64_t adbc = ad + emulu((uint32_t)ab, (uint32_t)(cd >> 32));
  uint64_t adbc_carry = !!(adbc < ad);
  uint64_t lo = bd + (adbc << 32);
  *hi = emulu((uint32_t)(ab >> 32), (uint32_t)(cd >> 32)) + (adbc >> 32) +
        (adbc_carry << 32) + !!(lo < bd);
  return lo;
}
#endif // !__MINGW64__

#endif // FASTFLOAT_32BIT


// compute 64-bit a*b
fastfloat_really_inline value128 full_multiplication(uint64_t a,
                                                     uint64_t b) {
  value128 answer;
#ifdef _M_ARM64
  // ARM64 has native support for 64-bit multiplications, no need to emulate
  answer.high = __umulh(a, b);
  answer.low = a * b;
#elif defined(FASTFLOAT_32BIT) || (defined(_WIN64) && !defined(__clang__))
  answer.low = _umul128(a, b, &answer.high); // _umul128 not available on ARM64
#elif defined(FASTFLOAT_64BIT)
  __uint128_t r = ((__uint128_t)a) * b;
  answer.low = uint64_t(r);
  answer.high = uint64_t(r >> 64);
#else
  #error Not implemented
#endif
  return answer;
}

struct adjusted_mantissa {
  uint64_t mantissa{0};
  int32_t power2{0}; // a negative value indicates an invalid result
  adjusted_mantissa() = default;
  bool operator==(const adjusted_mantissa &o) const {
    return mantissa == o.mantissa && power2 == o.power2;
  }
  bool operator!=(const adjusted_mantissa &o) const {
    return mantissa != o.mantissa || power2 != o.power2;
  }
};

// Bias so we can get the real exponent with an invalid adjusted_mantissa.
constexpr static int32_t invalid_am_bias = -0x8000;

constexpr static double powers_of_ten_double[] = {
    1e0,  1e1,  1e2,  1e3,  1e4,  1e5,  1e6,  1e7,  1e8,  1e9,  1e10, 1e11,
    1e12, 1e13, 1e14, 1e15, 1e16, 1e17, 1e18, 1e19, 1e20, 1e21, 1e22};
constexpr static float powers_of_ten_float[] = {1e0, 1e1, 1e2, 1e3, 1e4, 1e5,
                                                1e6, 1e7, 1e8, 1e9, 1e10};

template <typename T> struct binary_format {
  static inline constexpr int mantissa_explicit_bits();
  static inline constexpr int minimum_exponent();
  static inline constexpr int infinite_power();
  static inline constexpr int sign_index();
  static inline constexpr int min_exponent_fast_path();
  static inline constexpr int max_exponent_fast_path();
  static inline constexpr int max_exponent_round_to_even();
  static inline constexpr int min_exponent_round_to_even();
  static inline constexpr uint64_t max_mantissa_fast_path();
  static inline constexpr int largest_power_of_ten();
  static inline constexpr int smallest_power_of_ten();
  static inline constexpr T exact_power_of_ten(int64_t power);
  static inline constexpr size_t max_digits();
};

template <> inline constexpr int binary_format<double>::mantissa_explicit_bits() {
  return 52;
}
template <> inline constexpr int binary_format<float>::mantissa_explicit_bits() {
  return 23;
}

template <> inline constexpr int binary_format<double>::max_exponent_round_to_even() {
  return 23;
}

template <> inline constexpr int binary_format<float>::max_exponent_round_to_even() {
  return 10;
}

template <> inline constexpr int binary_format<double>::min_exponent_round_to_even() {
  return -4;
}

template <> inline constexpr int binary_format<float>::min_exponent_round_to_even() {
  return -17;
}

template <> inline constexpr int binary_format<double>::minimum_exponent() {
  return -1023;
}
template <> inline constexpr int binary_format<float>::minimum_exponent() {
  return -127;
}

template <> inline constexpr int binary_format<double>::infinite_power() {
  return 0x7FF;
}
template <> inline constexpr int binary_format<float>::infinite_power() {
  return 0xFF;
}

template <> inline constexpr int binary_format<double>::sign_index() { return 63; }
template <> inline constexpr int binary_format<float>::sign_index() { return 31; }

template <> inline constexpr int binary_format<double>::min_exponent_fast_path() {
#if (FLT_EVAL_METHOD != 1) && (FLT_EVAL_METHOD != 0)
  return 0;
#else
  return -22;
#endif
}
template <> inline constexpr int binary_format<float>::min_exponent_fast_path() {
#if (FLT_EVAL_METHOD != 1) && (FLT_EVAL_METHOD != 0)
  return 0;
#else
  return -10;
#endif
}

template <> inline constexpr int binary_format<double>::max_exponent_fast_path() {
  return 22;
}
template <> inline constexpr int binary_format<float>::max_exponent_fast_path() {
  return 10;
}

template <> inline constexpr uint64_t binary_format<double>::max_mantissa_fast_path() {
  return uint64_t(2) << mantissa_explicit_bits();
}
template <> inline constexpr uint64_t binary_format<float>::max_mantissa_fast_path() {
  return uint64_t(2) << mantissa_explicit_bits();
}

template <>
inline constexpr double binary_format<double>::exact_power_of_ten(int64_t power) {
  return powers_of_ten_double[power];
}
template <>
inline constexpr float binary_format<float>::exact_power_of_ten(int64_t power) {

  return powers_of_ten_float[power];
}


template <>
inline constexpr int binary_format<double>::largest_power_of_ten() {
  return 308;
}
template <>
inline constexpr int binary_format<float>::largest_power_of_ten() {
  return 38;
}

template <>
inline constexpr int binary_format<double>::smallest_power_of_ten() {
  return -342;
}
template <>
inline constexpr int binary_format<float>::smallest_power_of_ten() {
  return -65;
}

template <> inline constexpr size_t binary_format<double>::max_digits() {
  return 769;
}
template <> inline constexpr size_t binary_format<float>::max_digits() {
  return 114;
}

template<typename T>
fastfloat_really_inline void to_float(bool negative, adjusted_mantissa am, T &value) {
  uint64_t word = am.mantissa;
  word |= uint64_t(am.power2) << binary_format<T>::mantissa_explicit_bits();
  word = negative
  ? word | (uint64_t(1) << binary_format<T>::sign_index()) : word;
#if FASTFLOAT_IS_BIG_ENDIAN == 1
   if (std::is_same<T, float>::value) {
     ::memcpy(&value, (char *)&word + 4, sizeof(T)); // extract value at offset 4-7 if float on big-endian
   } else {
     ::memcpy(&value, &word, sizeof(T));
   }
#else
   // For little-endian systems:
   ::memcpy(&value, &word, sizeof(T));
#endif
}

} // namespace fast_float

#endif


#ifndef FASTFLOAT_ASCII_NUMBER_H
#define FASTFLOAT_ASCII_NUMBER_H

//included above:
//#include <cctype>
//included above:
//#include <cstdint>
//included above:
//#include <cstring>
#include <iterator>


namespace fast_float {

// Next function can be micro-optimized, but compilers are entirely
// able to optimize it well.
fastfloat_really_inline bool is_integer(char c)  noexcept  { return c >= '0' && c <= '9'; }

fastfloat_really_inline uint64_t byteswap(uint64_t val) {
  return (val & 0xFF00000000000000) >> 56
    | (val & 0x00FF000000000000) >> 40
    | (val & 0x0000FF0000000000) >> 24
    | (val & 0x000000FF00000000) >> 8
    | (val & 0x00000000FF000000) << 8
    | (val & 0x0000000000FF0000) << 24
    | (val & 0x000000000000FF00) << 40
    | (val & 0x00000000000000FF) << 56;
}

fastfloat_really_inline uint64_t read_u64(const char *chars) {
  uint64_t val;
  ::memcpy(&val, chars, sizeof(uint64_t));
#if FASTFLOAT_IS_BIG_ENDIAN == 1
  // Need to read as-if the number was in little-endian order.
  val = byteswap(val);
#endif
  return val;
}

fastfloat_really_inline void write_u64(uint8_t *chars, uint64_t val) {
#if FASTFLOAT_IS_BIG_ENDIAN == 1
  // Need to read as-if the number was in little-endian order.
  val = byteswap(val);
#endif
  ::memcpy(chars, &val, sizeof(uint64_t));
}

// credit  @aqrit
fastfloat_really_inline uint32_t  parse_eight_digits_unrolled(uint64_t val) {
  const uint64_t mask = 0x000000FF000000FF;
  const uint64_t mul1 = 0x000F424000000064; // 100 + (1000000ULL << 32)
  const uint64_t mul2 = 0x0000271000000001; // 1 + (10000ULL << 32)
  val -= 0x3030303030303030;
  val = (val * 10) + (val >> 8); // val = (val * 2561) >> 8;
  val = (((val & mask) * mul1) + (((val >> 16) & mask) * mul2)) >> 32;
  return uint32_t(val);
}

fastfloat_really_inline uint32_t parse_eight_digits_unrolled(const char *chars)  noexcept  {
  return parse_eight_digits_unrolled(read_u64(chars));
}

// credit @aqrit
fastfloat_really_inline bool is_made_of_eight_digits_fast(uint64_t val)  noexcept  {
  return !((((val + 0x4646464646464646) | (val - 0x3030303030303030)) &
     0x8080808080808080));
}

fastfloat_really_inline bool is_made_of_eight_digits_fast(const char *chars)  noexcept  {
  return is_made_of_eight_digits_fast(read_u64(chars));
}

typedef span<const char> byte_span;

struct parsed_number_string {
  int64_t exponent{0};
  uint64_t mantissa{0};
  const char *lastmatch{nullptr};
  bool negative{false};
  bool valid{false};
  bool too_many_digits{false};
  // contains the range of the significant digits
  byte_span integer{};  // non-nullable
  byte_span fraction{}; // nullable
};

// Assuming that you use no more than 19 digits, this will
// parse an ASCII string.
fastfloat_really_inline
parsed_number_string parse_number_string(const char *p, const char *pend, parse_options options) noexcept {
  const chars_format fmt = options.format;
  const char decimal_point = options.decimal_point;

  parsed_number_string answer;
  answer.valid = false;
  answer.too_many_digits = false;
  answer.negative = (*p == '-');
  if (*p == '-') { // C++17 20.19.3.(7.1) explicitly forbids '+' sign here
    ++p;
    if (p == pend) {
      return answer;
    }
    if (!is_integer(*p) && (*p != decimal_point)) { // a sign must be followed by an integer or the dot
      return answer;
    }
  }
  const char *const start_digits = p;

  uint64_t i = 0; // an unsigned int avoids signed overflows (which are bad)

  while ((std::distance(p, pend) >= 8) && is_made_of_eight_digits_fast(p)) {
    i = i * 100000000 + parse_eight_digits_unrolled(p); // in rare cases, this will overflow, but that's ok
    p += 8;
  }
  while ((p != pend) && is_integer(*p)) {
    // a multiplication by 10 is cheaper than an arbitrary integer
    // multiplication
    i = 10 * i +
        uint64_t(*p - '0'); // might overflow, we will handle the overflow later
    ++p;
  }
  const char *const end_of_integer_part = p;
  int64_t digit_count = int64_t(end_of_integer_part - start_digits);
  answer.integer = byte_span(start_digits, size_t(digit_count));
  int64_t exponent = 0;
  if ((p != pend) && (*p == decimal_point)) {
    ++p;
    const char* before = p;
    // can occur at most twice without overflowing, but let it occur more, since
    // for integers with many digits, digit parsing is the primary bottleneck.
    while ((std::distance(p, pend) >= 8) && is_made_of_eight_digits_fast(p)) {
      i = i * 100000000 + parse_eight_digits_unrolled(p); // in rare cases, this will overflow, but that's ok
      p += 8;
    }
    while ((p != pend) && is_integer(*p)) {
      uint8_t digit = uint8_t(*p - '0');
      ++p;
      i = i * 10 + digit; // in rare cases, this will overflow, but that's ok
    }
    exponent = before - p;
    answer.fraction = byte_span(before, size_t(p - before));
    digit_count -= exponent;
  }
  // we must have encountered at least one integer!
  if (digit_count == 0) {
    return answer;
  }
  int64_t exp_number = 0;            // explicit exponential part
  if ((fmt & chars_format::scientific) && (p != pend) && (('e' == *p) || ('E' == *p))) {
    const char * location_of_e = p;
    ++p;
    bool neg_exp = false;
    if ((p != pend) && ('-' == *p)) {
      neg_exp = true;
      ++p;
    } else if ((p != pend) && ('+' == *p)) { // '+' on exponent is allowed by C++17 20.19.3.(7.1)
      ++p;
    }
    if ((p == pend) || !is_integer(*p)) {
      if(!(fmt & chars_format::fixed)) {
        // We are in error.
        return answer;
      }
      // Otherwise, we will be ignoring the 'e'.
      p = location_of_e;
    } else {
      while ((p != pend) && is_integer(*p)) {
        uint8_t digit = uint8_t(*p - '0');
        if (exp_number < 0x10000000) {
          exp_number = 10 * exp_number + digit;
        }
        ++p;
      }
      if(neg_exp) { exp_number = - exp_number; }
      exponent += exp_number;
    }
  } else {
    // If it scientific and not fixed, we have to bail out.
    if((fmt & chars_format::scientific) && !(fmt & chars_format::fixed)) { return answer; }
  }
  answer.lastmatch = p;
  answer.valid = true;

  // If we frequently had to deal with long strings of digits,
  // we could extend our code by using a 128-bit integer instead
  // of a 64-bit integer. However, this is uncommon.
  //
  // We can deal with up to 19 digits.
  if (digit_count > 19) { // this is uncommon
    // It is possible that the integer had an overflow.
    // We have to handle the case where we have 0.0000somenumber.
    // We need to be mindful of the case where we only have zeroes...
    // E.g., 0.000000000...000.
    const char *start = start_digits;
    while ((start != pend) && (*start == '0' || *start == decimal_point)) {
      if(*start == '0') { digit_count --; }
      start++;
    }
    if (digit_count > 19) {
      answer.too_many_digits = true;
      // Let us start again, this time, avoiding overflows.
      // We don't need to check if is_integer, since we use the
      // pre-tokenized spans from above.
      i = 0;
      p = answer.integer.ptr;
      const char* int_end = p + answer.integer.len();
      const uint64_t minimal_nineteen_digit_integer{1000000000000000000};
      while((i < minimal_nineteen_digit_integer) && (p != int_end)) {
        i = i * 10 + uint64_t(*p - '0');
        ++p;
      }
      if (i >= minimal_nineteen_digit_integer) { // We have a big integers
        exponent = end_of_integer_part - p + exp_number;
      } else { // We have a value with a fractional component.
          p = answer.fraction.ptr;
          const char* frac_end = p + answer.fraction.len();
          while((i < minimal_nineteen_digit_integer) && (p != frac_end)) {
            i = i * 10 + uint64_t(*p - '0');
            ++p;
          }
          exponent = answer.fraction.ptr - p + exp_number;
      }
      // We have now corrected both exponent and i, to a truncated value
    }
  }
  answer.exponent = exponent;
  answer.mantissa = i;
  return answer;
}

} // namespace fast_float

#endif


#ifndef FASTFLOAT_FAST_TABLE_H
#define FASTFLOAT_FAST_TABLE_H

//included above:
//#include <cstdint>

namespace fast_float {

/**
 * When mapping numbers from decimal to binary,
 * we go from w * 10^q to m * 2^p but we have
 * 10^q = 5^q * 2^q, so effectively
 * we are trying to match
 * w * 2^q * 5^q to m * 2^p. Thus the powers of two
 * are not a concern since they can be represented
 * exactly using the binary notation, only the powers of five
 * affect the binary significand.
 */

/**
 * The smallest non-zero float (binary64) is 2^−1074.
 * We take as input numbers of the form w x 10^q where w < 2^64.
 * We have that w * 10^-343  <  2^(64-344) 5^-343 < 2^-1076.
 * However, we have that
 * (2^64-1) * 10^-342 =  (2^64-1) * 2^-342 * 5^-342 > 2^−1074.
 * Thus it is possible for a number of the form w * 10^-342 where
 * w is a 64-bit value to be a non-zero floating-point number.
 *********
 * Any number of form w * 10^309 where w>= 1 is going to be
 * infinite in binary64 so we never need to worry about powers
 * of 5 greater than 308.
 */
template <class unused = void>
struct powers_template {

constexpr static int smallest_power_of_five = binary_format<double>::smallest_power_of_ten();
constexpr static int largest_power_of_five = binary_format<double>::largest_power_of_ten();
constexpr static int number_of_entries = 2 * (largest_power_of_five - smallest_power_of_five + 1);
// Powers of five from 5^-342 all the way to 5^308 rounded toward one.
static const uint64_t power_of_five_128[number_of_entries];
};

template <class unused>
const uint64_t powers_template<unused>::power_of_five_128[number_of_entries] = {
        0xeef453d6923bd65a,0x113faa2906a13b3f,
        0x9558b4661b6565f8,0x4ac7ca59a424c507,
        0xbaaee17fa23ebf76,0x5d79bcf00d2df649,
        0xe95a99df8ace6f53,0xf4d82c2c107973dc,
        0x91d8a02bb6c10594,0x79071b9b8a4be869,
        0xb64ec836a47146f9,0x9748e2826cdee284,
        0xe3e27a444d8d98b7,0xfd1b1b2308169b25,
        0x8e6d8c6ab0787f72,0xfe30f0f5e50e20f7,
        0xb208ef855c969f4f,0xbdbd2d335e51a935,
        0xde8b2b66b3bc4723,0xad2c788035e61382,
        0x8b16fb203055ac76,0x4c3bcb5021afcc31,
        0xaddcb9e83c6b1793,0xdf4abe242a1bbf3d,
        0xd953e8624b85dd78,0xd71d6dad34a2af0d,
        0x87d4713d6f33aa6b,0x8672648c40e5ad68,
        0xa9c98d8ccb009506,0x680efdaf511f18c2,
        0xd43bf0effdc0ba48,0x212bd1b2566def2,
        0x84a57695fe98746d,0x14bb630f7604b57,
        0xa5ced43b7e3e9188,0x419ea3bd35385e2d,
        0xcf42894a5dce35ea,0x52064cac828675b9,
        0x818995ce7aa0e1b2,0x7343efebd1940993,
        0xa1ebfb4219491a1f,0x1014ebe6c5f90bf8,
        0xca66fa129f9b60a6,0xd41a26e077774ef6,
        0xfd00b897478238d0,0x8920b098955522b4,
        0x9e20735e8cb16382,0x55b46e5f5d5535b0,
        0xc5a890362fddbc62,0xeb2189f734aa831d,
        0xf712b443bbd52b7b,0xa5e9ec7501d523e4,
        0x9a6bb0aa55653b2d,0x47b233c92125366e,
        0xc1069cd4eabe89f8,0x999ec0bb696e840a,
        0xf148440a256e2c76,0xc00670ea43ca250d,
        0x96cd2a865764dbca,0x380406926a5e5728,
        0xbc807527ed3e12bc,0xc605083704f5ecf2,
        0xeba09271e88d976b,0xf7864a44c633682e,
        0x93445b8731587ea3,0x7ab3ee6afbe0211d,
        0xb8157268fdae9e4c,0x5960ea05bad82964,
        0xe61acf033d1a45df,0x6fb92487298e33bd,
        0x8fd0c16206306bab,0xa5d3b6d479f8e056,
        0xb3c4f1ba87bc8696,0x8f48a4899877186c,
        0xe0b62e2929aba83c,0x331acdabfe94de87,
        0x8c71dcd9ba0b4925,0x9ff0c08b7f1d0b14,
        0xaf8e5410288e1b6f,0x7ecf0ae5ee44dd9,
        0xdb71e91432b1a24a,0xc9e82cd9f69d6150,
        0x892731ac9faf056e,0xbe311c083a225cd2,
        0xab70fe17c79ac6ca,0x6dbd630a48aaf406,
        0xd64d3d9db981787d,0x92cbbccdad5b108,
        0x85f0468293f0eb4e,0x25bbf56008c58ea5,
        0xa76c582338ed2621,0xaf2af2b80af6f24e,
        0xd1476e2c07286faa,0x1af5af660db4aee1,
        0x82cca4db847945ca,0x50d98d9fc890ed4d,
        0xa37fce126597973c,0xe50ff107bab528a0,
        0xcc5fc196fefd7d0c,0x1e53ed49a96272c8,
        0xff77b1fcbebcdc4f,0x25e8e89c13bb0f7a,
        0x9faacf3df73609b1,0x77b191618c54e9ac,
        0xc795830d75038c1d,0xd59df5b9ef6a2417,
        0xf97ae3d0d2446f25,0x4b0573286b44ad1d,
        0x9becce62836ac577,0x4ee367f9430aec32,
        0xc2e801fb244576d5,0x229c41f793cda73f,
        0xf3a20279ed56d48a,0x6b43527578c1110f,
        0x9845418c345644d6,0x830a13896b78aaa9,
        0xbe5691ef416bd60c,0x23cc986bc656d553,
        0xedec366b11c6cb8f,0x2cbfbe86b7ec8aa8,
        0x94b3a202eb1c3f39,0x7bf7d71432f3d6a9,
        0xb9e08a83a5e34f07,0xdaf5ccd93fb0cc53,
        0xe858ad248f5c22c9,0xd1b3400f8f9cff68,
        0x91376c36d99995be,0x23100809b9c21fa1,
        0xb58547448ffffb2d,0xabd40a0c2832a78a,
        0xe2e69915b3fff9f9,0x16c90c8f323f516c,
        0x8dd01fad907ffc3b,0xae3da7d97f6792e3,
        0xb1442798f49ffb4a,0x99cd11cfdf41779c,
        0xdd95317f31c7fa1d,0x40405643d711d583,
        0x8a7d3eef7f1cfc52,0x482835ea666b2572,
        0xad1c8eab5ee43b66,0xda3243650005eecf,
        0xd863b256369d4a40,0x90bed43e40076a82,
        0x873e4f75e2224e68,0x5a7744a6e804a291,
        0xa90de3535aaae202,0x711515d0a205cb36,
        0xd3515c2831559a83,0xd5a5b44ca873e03,
        0x8412d9991ed58091,0xe858790afe9486c2,
        0xa5178fff668ae0b6,0x626e974dbe39a872,
        0xce5d73ff402d98e3,0xfb0a3d212dc8128f,
        0x80fa687f881c7f8e,0x7ce66634bc9d0b99,
        0xa139029f6a239f72,0x1c1fffc1ebc44e80,
        0xc987434744ac874e,0xa327ffb266b56220,
        0xfbe9141915d7a922,0x4bf1ff9f0062baa8,
        0x9d71ac8fada6c9b5,0x6f773fc3603db4a9,
        0xc4ce17b399107c22,0xcb550fb4384d21d3,
        0xf6019da07f549b2b,0x7e2a53a146606a48,
        0x99c102844f94e0fb,0x2eda7444cbfc426d,
        0xc0314325637a1939,0xfa911155fefb5308,
        0xf03d93eebc589f88,0x793555ab7eba27ca,
        0x96267c7535b763b5,0x4bc1558b2f3458de,
        0xbbb01b9283253ca2,0x9eb1aaedfb016f16,
        0xea9c227723ee8bcb,0x465e15a979c1cadc,
        0x92a1958a7675175f,0xbfacd89ec191ec9,
        0xb749faed14125d36,0xcef980ec671f667b,
        0xe51c79a85916f484,0x82b7e12780e7401a,
        0x8f31cc0937ae58d2,0xd1b2ecb8b0908810,
        0xb2fe3f0b8599ef07,0x861fa7e6dcb4aa15,
        0xdfbdcece67006ac9,0x67a791e093e1d49a,
        0x8bd6a141006042bd,0xe0c8bb2c5c6d24e0,
        0xaecc49914078536d,0x58fae9f773886e18,
        0xda7f5bf590966848,0xaf39a475506a899e,
        0x888f99797a5e012d,0x6d8406c952429603,
        0xaab37fd7d8f58178,0xc8e5087ba6d33b83,
        0xd5605fcdcf32e1d6,0xfb1e4a9a90880a64,
        0x855c3be0a17fcd26,0x5cf2eea09a55067f,
        0xa6b34ad8c9dfc06f,0xf42faa48c0ea481e,
        0xd0601d8efc57b08b,0xf13b94daf124da26,
        0x823c12795db6ce57,0x76c53d08d6b70858,
        0xa2cb1717b52481ed,0x54768c4b0c64ca6e,
        0xcb7ddcdda26da268,0xa9942f5dcf7dfd09,
        0xfe5d54150b090b02,0xd3f93b35435d7c4c,
        0x9efa548d26e5a6e1,0xc47bc5014a1a6daf,
        0xc6b8e9b0709f109a,0x359ab6419ca1091b,
        0xf867241c8cc6d4c0,0xc30163d203c94b62,
        0x9b407691d7fc44f8,0x79e0de63425dcf1d,
        0xc21094364dfb5636,0x985915fc12f542e4,
        0xf294b943e17a2bc4,0x3e6f5b7b17b2939d,
        0x979cf3ca6cec5b5a,0xa705992ceecf9c42,
        0xbd8430bd08277231,0x50c6ff782a838353,
        0xece53cec4a314ebd,0xa4f8bf5635246428,
        0x940f4613ae5ed136,0x871b7795e136be99,
        0xb913179899f68584,0x28e2557b59846e3f,
        0xe757dd7ec07426e5,0x331aeada2fe589cf,
        0x9096ea6f3848984f,0x3ff0d2c85def7621,
        0xb4bca50b065abe63,0xfed077a756b53a9,
        0xe1ebce4dc7f16dfb,0xd3e8495912c62894,
        0x8d3360f09cf6e4bd,0x64712dd7abbbd95c,
        0xb080392cc4349dec,0xbd8d794d96aacfb3,
        0xdca04777f541c567,0xecf0d7a0fc5583a0,
        0x89e42caaf9491b60,0xf41686c49db57244,
        0xac5d37d5b79b6239,0x311c2875c522ced5,
        0xd77485cb25823ac7,0x7d633293366b828b,
        0x86a8d39ef77164bc,0xae5dff9c02033197,
        0xa8530886b54dbdeb,0xd9f57f830283fdfc,
        0xd267caa862a12d66,0xd072df63c324fd7b,
        0x8380dea93da4bc60,0x4247cb9e59f71e6d,
        0xa46116538d0deb78,0x52d9be85f074e608,
        0xcd795be870516656,0x67902e276c921f8b,
        0x806bd9714632dff6,0xba1cd8a3db53b6,
        0xa086cfcd97bf97f3,0x80e8a40eccd228a4,
        0xc8a883c0fdaf7df0,0x6122cd128006b2cd,
        0xfad2a4b13d1b5d6c,0x796b805720085f81,
        0x9cc3a6eec6311a63,0xcbe3303674053bb0,
        0xc3f490aa77bd60fc,0xbedbfc4411068a9c,
        0xf4f1b4d515acb93b,0xee92fb5515482d44,
        0x991711052d8bf3c5,0x751bdd152d4d1c4a,
        0xbf5cd54678eef0b6,0xd262d45a78a0635d,
        0xef340a98172aace4,0x86fb897116c87c34,
        0x9580869f0e7aac0e,0xd45d35e6ae3d4da0,
        0xbae0a846d2195712,0x8974836059cca109,
        0xe998d258869facd7,0x2bd1a438703fc94b,
        0x91ff83775423cc06,0x7b6306a34627ddcf,
        0xb67f6455292cbf08,0x1a3bc84c17b1d542,
        0xe41f3d6a7377eeca,0x20caba5f1d9e4a93,
        0x8e938662882af53e,0x547eb47b7282ee9c,
        0xb23867fb2a35b28d,0xe99e619a4f23aa43,
        0xdec681f9f4c31f31,0x6405fa00e2ec94d4,
        0x8b3c113c38f9f37e,0xde83bc408dd3dd04,
        0xae0b158b4738705e,0x9624ab50b148d445,
        0xd98ddaee19068c76,0x3badd624dd9b0957,
        0x87f8a8d4cfa417c9,0xe54ca5d70a80e5d6,
        0xa9f6d30a038d1dbc,0x5e9fcf4ccd211f4c,
        0xd47487cc8470652b,0x7647c3200069671f,
        0x84c8d4dfd2c63f3b,0x29ecd9f40041e073,
        0xa5fb0a17c777cf09,0xf468107100525890,
        0xcf79cc9db955c2cc,0x7182148d4066eeb4,
        0x81ac1fe293d599bf,0xc6f14cd848405530,
        0xa21727db38cb002f,0xb8ada00e5a506a7c,
        0xca9cf1d206fdc03b,0xa6d90811f0e4851c,
        0xfd442e4688bd304a,0x908f4a166d1da663,
        0x9e4a9cec15763e2e,0x9a598e4e043287fe,
        0xc5dd44271ad3cdba,0x40eff1e1853f29fd,
        0xf7549530e188c128,0xd12bee59e68ef47c,
        0x9a94dd3e8cf578b9,0x82bb74f8301958ce,
        0xc13a148e3032d6e7,0xe36a52363c1faf01,
        0xf18899b1bc3f8ca1,0xdc44e6c3cb279ac1,
        0x96f5600f15a7b7e5,0x29ab103a5ef8c0b9,
        0xbcb2b812db11a5de,0x7415d448f6b6f0e7,
        0xebdf661791d60f56,0x111b495b3464ad21,
        0x936b9fcebb25c995,0xcab10dd900beec34,
        0xb84687c269ef3bfb,0x3d5d514f40eea742,
        0xe65829b3046b0afa,0xcb4a5a3112a5112,
        0x8ff71a0fe2c2e6dc,0x47f0e785eaba72ab,
        0xb3f4e093db73a093,0x59ed216765690f56,
        0xe0f218b8d25088b8,0x306869c13ec3532c,
        0x8c974f7383725573,0x1e414218c73a13fb,
        0xafbd2350644eeacf,0xe5d1929ef90898fa,
        0xdbac6c247d62a583,0xdf45f746b74abf39,
        0x894bc396ce5da772,0x6b8bba8c328eb783,
        0xab9eb47c81f5114f,0x66ea92f3f326564,
        0xd686619ba27255a2,0xc80a537b0efefebd,
        0x8613fd0145877585,0xbd06742ce95f5f36,
        0xa798fc4196e952e7,0x2c48113823b73704,
        0xd17f3b51fca3a7a0,0xf75a15862ca504c5,
        0x82ef85133de648c4,0x9a984d73dbe722fb,
        0xa3ab66580d5fdaf5,0xc13e60d0d2e0ebba,
        0xcc963fee10b7d1b3,0x318df905079926a8,
        0xffbbcfe994e5c61f,0xfdf17746497f7052,
        0x9fd561f1fd0f9bd3,0xfeb6ea8bedefa633,
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        0xb1d219647ae6b31c,0x596eb2d8ae258fc8,
        0xde469fbd99a05fe3,0x6fca5f8ed9aef3bb,
        0x8aec23d680043bee,0x25de7bb9480d5854,
        0xada72ccc20054ae9,0xaf561aa79a10ae6a,
        0xd910f7ff28069da4,0x1b2ba1518094da04,
        0x87aa9aff79042286,0x90fb44d2f05d0842,
        0xa99541bf57452b28,0x353a1607ac744a53,
        0xd3fa922f2d1675f2,0x42889b8997915ce8,
        0x847c9b5d7c2e09b7,0x69956135febada11,
        0xa59bc234db398c25,0x43fab9837e699095,
        0xcf02b2c21207ef2e,0x94f967e45e03f4bb,
        0x8161afb94b44f57d,0x1d1be0eebac278f5,
        0xa1ba1ba79e1632dc,0x6462d92a69731732,
        0xca28a291859bbf93,0x7d7b8f7503cfdcfe,
        0xfcb2cb35e702af78,0x5cda735244c3d43e,
        0x9defbf01b061adab,0x3a0888136afa64a7,
        0xc56baec21c7a1916,0x88aaa1845b8fdd0,
        0xf6c69a72a3989f5b,0x8aad549e57273d45,
        0x9a3c2087a63f6399,0x36ac54e2f678864b,
        0xc0cb28a98fcf3c7f,0x84576a1bb416a7dd,
        0xf0fdf2d3f3c30b9f,0x656d44a2a11c51d5,
        0x969eb7c47859e743,0x9f644ae5a4b1b325,
        0xbc4665b596706114,0x873d5d9f0dde1fee,
        0xeb57ff22fc0c7959,0xa90cb506d155a7ea,
        0x9316ff75dd87cbd8,0x9a7f12442d588f2,
        0xb7dcbf5354e9bece,0xc11ed6d538aeb2f,
        0xe5d3ef282a242e81,0x8f1668c8a86da5fa,
        0x8fa475791a569d10,0xf96e017d694487bc,
        0xb38d92d760ec4455,0x37c981dcc395a9ac,
        0xe070f78d3927556a,0x85bbe253f47b1417,
        0x8c469ab843b89562,0x93956d7478ccec8e,
        0xaf58416654a6babb,0x387ac8d1970027b2,
        0xdb2e51bfe9d0696a,0x6997b05fcc0319e,
        0x88fcf317f22241e2,0x441fece3bdf81f03,
        0xab3c2fddeeaad25a,0xd527e81cad7626c3,
        0xd60b3bd56a5586f1,0x8a71e223d8d3b074,
        0x85c7056562757456,0xf6872d5667844e49,
        0xa738c6bebb12d16c,0xb428f8ac016561db,
        0xd106f86e69d785c7,0xe13336d701beba52,
        0x82a45b450226b39c,0xecc0024661173473,
        0xa34d721642b06084,0x27f002d7f95d0190,
        0xcc20ce9bd35c78a5,0x31ec038df7b441f4,
        0xff290242c83396ce,0x7e67047175a15271,
        0x9f79a169bd203e41,0xf0062c6e984d386,
        0xc75809c42c684dd1,0x52c07b78a3e60868,
        0xf92e0c3537826145,0xa7709a56ccdf8a82,
        0x9bbcc7a142b17ccb,0x88a66076400bb691,
        0xc2abf989935ddbfe,0x6acff893d00ea435,
        0xf356f7ebf83552fe,0x583f6b8c4124d43,
        0x98165af37b2153de,0xc3727a337a8b704a,
        0xbe1bf1b059e9a8d6,0x744f18c0592e4c5c,
        0xeda2ee1c7064130c,0x1162def06f79df73,
        0x9485d4d1c63e8be7,0x8addcb5645ac2ba8,
        0xb9a74a0637ce2ee1,0x6d953e2bd7173692,
        0xe8111c87c5c1ba99,0xc8fa8db6ccdd0437,
        0x910ab1d4db9914a0,0x1d9c9892400a22a2,
        0xb54d5e4a127f59c8,0x2503beb6d00cab4b,
        0xe2a0b5dc971f303a,0x2e44ae64840fd61d,
        0x8da471a9de737e24,0x5ceaecfed289e5d2,
        0xb10d8e1456105dad,0x7425a83e872c5f47,
        0xdd50f1996b947518,0xd12f124e28f77719,
        0x8a5296ffe33cc92f,0x82bd6b70d99aaa6f,
        0xace73cbfdc0bfb7b,0x636cc64d1001550b,
        0xd8210befd30efa5a,0x3c47f7e05401aa4e,
        0x8714a775e3e95c78,0x65acfaec34810a71,
        0xa8d9d1535ce3b396,0x7f1839a741a14d0d,
        0xd31045a8341ca07c,0x1ede48111209a050,
        0x83ea2b892091e44d,0x934aed0aab460432,
        0xa4e4b66b68b65d60,0xf81da84d5617853f,
        0xce1de40642e3f4b9,0x36251260ab9d668e,
        0x80d2ae83e9ce78f3,0xc1d72b7c6b426019,
        0xa1075a24e4421730,0xb24cf65b8612f81f,
        0xc94930ae1d529cfc,0xdee033f26797b627,
        0xfb9b7cd9a4a7443c,0x169840ef017da3b1,
        0x9d412e0806e88aa5,0x8e1f289560ee864e,
        0xc491798a08a2ad4e,0xf1a6f2bab92a27e2,
        0xf5b5d7ec8acb58a2,0xae10af696774b1db,
        0x9991a6f3d6bf1765,0xacca6da1e0a8ef29,
        0xbff610b0cc6edd3f,0x17fd090a58d32af3,
        0xeff394dcff8a948e,0xddfc4b4cef07f5b0,
        0x95f83d0a1fb69cd9,0x4abdaf101564f98e,
        0xbb764c4ca7a4440f,0x9d6d1ad41abe37f1,
        0xea53df5fd18d5513,0x84c86189216dc5ed,
        0x92746b9be2f8552c,0x32fd3cf5b4e49bb4,
        0xb7118682dbb66a77,0x3fbc8c33221dc2a1,
        0xe4d5e82392a40515,0xfabaf3feaa5334a,
        0x8f05b1163ba6832d,0x29cb4d87f2a7400e,
        0xb2c71d5bca9023f8,0x743e20e9ef511012,
        0xdf78e4b2bd342cf6,0x914da9246b255416,
        0x8bab8eefb6409c1a,0x1ad089b6c2f7548e,
        0xae9672aba3d0c320,0xa184ac2473b529b1,
        0xda3c0f568cc4f3e8,0xc9e5d72d90a2741e,
        0x8865899617fb1871,0x7e2fa67c7a658892,
        0xaa7eebfb9df9de8d,0xddbb901b98feeab7,
        0xd51ea6fa85785631,0x552a74227f3ea565,
        0x8533285c936b35de,0xd53a88958f87275f,
        0xa67ff273b8460356,0x8a892abaf368f137,
        0xd01fef10a657842c,0x2d2b7569b0432d85,
        0x8213f56a67f6b29b,0x9c3b29620e29fc73,
        0xa298f2c501f45f42,0x8349f3ba91b47b8f,
        0xcb3f2f7642717713,0x241c70a936219a73,
        0xfe0efb53d30dd4d7,0xed238cd383aa0110,
        0x9ec95d1463e8a506,0xf4363804324a40aa,
        0xc67bb4597ce2ce48,0xb143c6053edcd0d5,
        0xf81aa16fdc1b81da,0xdd94b7868e94050a,
        0x9b10a4e5e9913128,0xca7cf2b4191c8326,
        0xc1d4ce1f63f57d72,0xfd1c2f611f63a3f0,
        0xf24a01a73cf2dccf,0xbc633b39673c8cec,
        0x976e41088617ca01,0xd5be0503e085d813,
        0xbd49d14aa79dbc82,0x4b2d8644d8a74e18,
        0xec9c459d51852ba2,0xddf8e7d60ed1219e,
        0x93e1ab8252f33b45,0xcabb90e5c942b503,
        0xb8da1662e7b00a17,0x3d6a751f3b936243,
        0xe7109bfba19c0c9d,0xcc512670a783ad4,
        0x906a617d450187e2,0x27fb2b80668b24c5,
        0xb484f9dc9641e9da,0xb1f9f660802dedf6,
        0xe1a63853bbd26451,0x5e7873f8a0396973,
        0x8d07e33455637eb2,0xdb0b487b6423e1e8,
        0xb049dc016abc5e5f,0x91ce1a9a3d2cda62,
        0xdc5c5301c56b75f7,0x7641a140cc7810fb,
        0x89b9b3e11b6329ba,0xa9e904c87fcb0a9d,
        0xac2820d9623bf429,0x546345fa9fbdcd44,
        0xd732290fbacaf133,0xa97c177947ad4095,
        0x867f59a9d4bed6c0,0x49ed8eabcccc485d,
        0xa81f301449ee8c70,0x5c68f256bfff5a74,
        0xd226fc195c6a2f8c,0x73832eec6fff3111,
        0x83585d8fd9c25db7,0xc831fd53c5ff7eab,
        0xa42e74f3d032f525,0xba3e7ca8b77f5e55,
        0xcd3a1230c43fb26f,0x28ce1bd2e55f35eb,
        0x80444b5e7aa7cf85,0x7980d163cf5b81b3,
        0xa0555e361951c366,0xd7e105bcc332621f,
        0xc86ab5c39fa63440,0x8dd9472bf3fefaa7,
        0xfa856334878fc150,0xb14f98f6f0feb951,
        0x9c935e00d4b9d8d2,0x6ed1bf9a569f33d3,
        0xc3b8358109e84f07,0xa862f80ec4700c8,
        0xf4a642e14c6262c8,0xcd27bb612758c0fa,
        0x98e7e9cccfbd7dbd,0x8038d51cb897789c,
        0xbf21e44003acdd2c,0xe0470a63e6bd56c3,
        0xeeea5d5004981478,0x1858ccfce06cac74,
        0x95527a5202df0ccb,0xf37801e0c43ebc8,
        0xbaa718e68396cffd,0xd30560258f54e6ba,
        0xe950df20247c83fd,0x47c6b82ef32a2069,
        0x91d28b7416cdd27e,0x4cdc331d57fa5441,
        0xb6472e511c81471d,0xe0133fe4adf8e952,
        0xe3d8f9e563a198e5,0x58180fddd97723a6,
        0x8e679c2f5e44ff8f,0x570f09eaa7ea7648,};
using powers = powers_template<>;

}

#endif


#ifndef FASTFLOAT_DECIMAL_TO_BINARY_H
#define FASTFLOAT_DECIMAL_TO_BINARY_H

//included above:
//#include <cfloat>
#include <cinttypes>
#include <cmath>
//included above:
//#include <cstdint>
#include <cstdlib>
//included above:
//#include <cstring>

namespace fast_float {

// This will compute or rather approximate w * 5**q and return a pair of 64-bit words approximating
// the result, with the "high" part corresponding to the most significant bits and the
// low part corresponding to the least significant bits.
//
template <int bit_precision>
fastfloat_really_inline
value128 compute_product_approximation(int64_t q, uint64_t w) {
  const int index = 2 * int(q - powers::smallest_power_of_five);
  // For small values of q, e.g., q in [0,27], the answer is always exact because
  // The line value128 firstproduct = full_multiplication(w, power_of_five_128[index]);
  // gives the exact answer.
  value128 firstproduct = full_multiplication(w, powers::power_of_five_128[index]);
  static_assert((bit_precision >= 0) && (bit_precision <= 64), " precision should  be in (0,64]");
  constexpr uint64_t precision_mask = (bit_precision < 64) ?
               (uint64_t(0xFFFFFFFFFFFFFFFF) >> bit_precision)
               : uint64_t(0xFFFFFFFFFFFFFFFF);
  if((firstproduct.high & precision_mask) == precision_mask) { // could further guard with  (lower + w < lower)
    // regarding the second product, we only need secondproduct.high, but our expectation is that the compiler will optimize this extra work away if needed.
    value128 secondproduct = full_multiplication(w, powers::power_of_five_128[index + 1]);
    firstproduct.low += secondproduct.high;
    if(secondproduct.high > firstproduct.low) {
      firstproduct.high++;
    }
  }
  return firstproduct;
}

namespace detail {
/**
 * For q in (0,350), we have that
 *  f = (((152170 + 65536) * q ) >> 16);
 * is equal to
 *   floor(p) + q
 * where
 *   p = log(5**q)/log(2) = q * log(5)/log(2)
 *
 * For negative values of q in (-400,0), we have that
 *  f = (((152170 + 65536) * q ) >> 16);
 * is equal to
 *   -ceil(p) + q
 * where
 *   p = log(5**-q)/log(2) = -q * log(5)/log(2)
 */
  constexpr fastfloat_really_inline int32_t power(int32_t q)  noexcept  {
    return (((152170 + 65536) * q) >> 16) + 63;
  }
} // namespace detail

// create an adjusted mantissa, biased by the invalid power2
// for significant digits already multiplied by 10 ** q.
template <typename binary>
fastfloat_really_inline
adjusted_mantissa compute_error_scaled(int64_t q, uint64_t w, int lz) noexcept  {
  int hilz = int(w >> 63) ^ 1;
  adjusted_mantissa answer;
  answer.mantissa = w << hilz;
  int bias = binary::mantissa_explicit_bits() - binary::minimum_exponent();
  answer.power2 = int32_t(detail::power(int32_t(q)) + bias - hilz - lz - 62 + invalid_am_bias);
  return answer;
}

// w * 10 ** q, without rounding the representation up.
// the power2 in the exponent will be adjusted by invalid_am_bias.
template <typename binary>
fastfloat_really_inline
adjusted_mantissa compute_error(int64_t q, uint64_t w)  noexcept  {
  int lz = leading_zeroes(w);
  w <<= lz;
  value128 product = compute_product_approximation<binary::mantissa_explicit_bits() + 3>(q, w);
  return compute_error_scaled<binary>(q, product.high, lz);
}

// w * 10 ** q
// The returned value should be a valid ieee64 number that simply need to be packed.
// However, in some very rare cases, the computation will fail. In such cases, we
// return an adjusted_mantissa with a negative power of 2: the caller should recompute
// in such cases.
template <typename binary>
fastfloat_really_inline
adjusted_mantissa compute_float(int64_t q, uint64_t w)  noexcept  {
  adjusted_mantissa answer;
  if ((w == 0) || (q < binary::smallest_power_of_ten())) {
    answer.power2 = 0;
    answer.mantissa = 0;
    // result should be zero
    return answer;
  }
  if (q > binary::largest_power_of_ten()) {
    // we want to get infinity:
    answer.power2 = binary::infinite_power();
    answer.mantissa = 0;
    return answer;
  }
  // At this point in time q is in [powers::smallest_power_of_five, powers::largest_power_of_five].

  // We want the most significant bit of i to be 1. Shift if needed.
  int lz = leading_zeroes(w);
  w <<= lz;

  // The required precision is binary::mantissa_explicit_bits() + 3 because
  // 1. We need the implicit bit
  // 2. We need an extra bit for rounding purposes
  // 3. We might lose a bit due to the "upperbit" routine (result too small, requiring a shift)

  value128 product = compute_product_approximation<binary::mantissa_explicit_bits() + 3>(q, w);
  if(product.low == 0xFFFFFFFFFFFFFFFF) { //  could guard it further
    // In some very rare cases, this could happen, in which case we might need a more accurate
    // computation that what we can provide cheaply. This is very, very unlikely.
    //
    const bool inside_safe_exponent = (q >= -27) && (q <= 55); // always good because 5**q <2**128 when q>=0,
    // and otherwise, for q<0, we have 5**-q<2**64 and the 128-bit reciprocal allows for exact computation.
    if(!inside_safe_exponent) {
      return compute_error_scaled<binary>(q, product.high, lz);
    }
  }
  // The "compute_product_approximation" function can be slightly slower than a branchless approach:
  // value128 product = compute_product(q, w);
  // but in practice, we can win big with the compute_product_approximation if its additional branch
  // is easily predicted. Which is best is data specific.
  int upperbit = int(product.high >> 63);

  answer.mantissa = product.high >> (upperbit + 64 - binary::mantissa_explicit_bits() - 3);

  answer.power2 = int32_t(detail::power(int32_t(q)) + upperbit - lz - binary::minimum_exponent());
  if (answer.power2 <= 0) { // we have a subnormal?
    // Here have that answer.power2 <= 0 so -answer.power2 >= 0
    if(-answer.power2 + 1 >= 64) { // if we have more than 64 bits below the minimum exponent, you have a zero for sure.
      answer.power2 = 0;
      answer.mantissa = 0;
      // result should be zero
      return answer;
    }
    // next line is safe because -answer.power2 + 1 < 64
    answer.mantissa >>= -answer.power2 + 1;
    // Thankfully, we can't have both "round-to-even" and subnormals because
    // "round-to-even" only occurs for powers close to 0.
    answer.mantissa += (answer.mantissa & 1); // round up
    answer.mantissa >>= 1;
    // There is a weird scenario where we don't have a subnormal but just.
    // Suppose we start with 2.2250738585072013e-308, we end up
    // with 0x3fffffffffffff x 2^-1023-53 which is technically subnormal
    // whereas 0x40000000000000 x 2^-1023-53  is normal. Now, we need to round
    // up 0x3fffffffffffff x 2^-1023-53  and once we do, we are no longer
    // subnormal, but we can only know this after rounding.
    // So we only declare a subnormal if we are smaller than the threshold.
    answer.power2 = (answer.mantissa < (uint64_t(1) << binary::mantissa_explicit_bits())) ? 0 : 1;
    return answer;
  }

  // usually, we round *up*, but if we fall right in between and and we have an
  // even basis, we need to round down
  // We are only concerned with the cases where 5**q fits in single 64-bit word.
  if ((product.low <= 1) &&  (q >= binary::min_exponent_round_to_even()) && (q <= binary::max_exponent_round_to_even()) &&
      ((answer.mantissa & 3) == 1) ) { // we may fall between two floats!
    // To be in-between two floats we need that in doing
    //   answer.mantissa = product.high >> (upperbit + 64 - binary::mantissa_explicit_bits() - 3);
    // ... we dropped out only zeroes. But if this happened, then we can go back!!!
    if((answer.mantissa  << (upperbit + 64 - binary::mantissa_explicit_bits() - 3)) ==  product.high) {
      answer.mantissa &= ~uint64_t(1);          // flip it so that we do not round up
    }
  }

  answer.mantissa += (answer.mantissa & 1); // round up
  answer.mantissa >>= 1;
  if (answer.mantissa >= (uint64_t(2) << binary::mantissa_explicit_bits())) {
    answer.mantissa = (uint64_t(1) << binary::mantissa_explicit_bits());
    answer.power2++; // undo previous addition
  }

  answer.mantissa &= ~(uint64_t(1) << binary::mantissa_explicit_bits());
  if (answer.power2 >= binary::infinite_power()) { // infinity
    answer.power2 = binary::infinite_power();
    answer.mantissa = 0;
  }
  return answer;
}

} // namespace fast_float

#endif


#ifndef FASTFLOAT_BIGINT_H
#define FASTFLOAT_BIGINT_H

#include <algorithm>
//included above:
//#include <cstdint>
//included above:
//#include <climits>
//included above:
//#include <cstring>


namespace fast_float {

// the limb width: we want efficient multiplication of double the bits in
// limb, or for 64-bit limbs, at least 64-bit multiplication where we can
// extract the high and low parts efficiently. this is every 64-bit
// architecture except for sparc, which emulates 128-bit multiplication.
// we might have platforms where `CHAR_BIT` is not 8, so let's avoid
// doing `8 * sizeof(limb)`.
#if defined(FASTFLOAT_64BIT) && !defined(__sparc)
#define FASTFLOAT_64BIT_LIMB
typedef uint64_t limb;
constexpr size_t limb_bits = 64;
#else
#define FASTFLOAT_32BIT_LIMB
typedef uint32_t limb;
constexpr size_t limb_bits = 32;
#endif

typedef span<limb> limb_span;

// number of bits in a bigint. this needs to be at least the number
// of bits required to store the largest bigint, which is
// `log2(10**(digits + max_exp))`, or `log2(10**(767 + 342))`, or
// ~3600 bits, so we round to 4000.
constexpr size_t bigint_bits = 4000;
constexpr size_t bigint_limbs = bigint_bits / limb_bits;

// vector-like type that is allocated on the stack. the entire
// buffer is pre-allocated, and only the length changes.
template <uint16_t size>
struct stackvec {
  limb data[size];
  // we never need more than 150 limbs
  uint16_t length{0};

  stackvec() = default;
  stackvec(const stackvec &) = delete;
  stackvec &operator=(const stackvec &) = delete;
  stackvec(stackvec &&) = delete;
  stackvec &operator=(stackvec &&other) = delete;

  // create stack vector from existing limb span.
  stackvec(limb_span s) {
    FASTFLOAT_ASSERT(try_extend(s));
  }

  limb& operator[](size_t index) noexcept {
    FASTFLOAT_DEBUG_ASSERT(index < length);
    return data[index];
  }
  const limb& operator[](size_t index) const noexcept {
    FASTFLOAT_DEBUG_ASSERT(index < length);
    return data[index];
  }
  // index from the end of the container
  const limb& rindex(size_t index) const noexcept {
    FASTFLOAT_DEBUG_ASSERT(index < length);
    size_t rindex = length - index - 1;
    return data[rindex];
  }

  // set the length, without bounds checking.
  void set_len(size_t len) noexcept {
    length = uint16_t(len);
  }
  constexpr size_t len() const noexcept {
    return length;
  }
  constexpr bool is_empty() const noexcept {
    return length == 0;
  }
  constexpr size_t capacity() const noexcept {
    return size;
  }
  // append item to vector, without bounds checking
  void push_unchecked(limb value) noexcept {
    data[length] = value;
    length++;
  }
  // append item to vector, returning if item was added
  bool try_push(limb value) noexcept {
    if (len() < capacity()) {
      push_unchecked(value);
      return true;
    } else {
      return false;
    }
  }
  // add items to the vector, from a span, without bounds checking
  void extend_unchecked(limb_span s) noexcept {
    limb* ptr = data + length;
    ::memcpy((void*)ptr, (const void*)s.ptr, sizeof(limb) * s.len());
    set_len(len() + s.len());
  }
  // try to add items to the vector, returning if items were added
  bool try_extend(limb_span s) noexcept {
    if (len() + s.len() <= capacity()) {
      extend_unchecked(s);
      return true;
    } else {
      return false;
    }
  }
  // resize the vector, without bounds checking
  // if the new size is longer than the vector, assign value to each
  // appended item.
  void resize_unchecked(size_t new_len, limb value) noexcept {
    if (new_len > len()) {
      size_t count = new_len - len();
      limb* first = data + len();
      limb* last = first + count;
      ::std::fill(first, last, value);
      set_len(new_len);
    } else {
      set_len(new_len);
    }
  }
  // try to resize the vector, returning if the vector was resized.
  bool try_resize(size_t new_len, limb value) noexcept {
    if (new_len > capacity()) {
      return false;
    } else {
      resize_unchecked(new_len, value);
      return true;
    }
  }
  // check if any limbs are non-zero after the given index.
  // this needs to be done in reverse order, since the index
  // is relative to the most significant limbs.
  bool nonzero(size_t index) const noexcept {
    while (index < len()) {
      if (rindex(index) != 0) {
        return true;
      }
      index++;
    }
    return false;
  }
  // normalize the big integer, so most-significant zero limbs are removed.
  void normalize() noexcept {
    while (len() > 0 && rindex(0) == 0) {
      length--;
    }
  }
};

fastfloat_really_inline
uint64_t empty_hi64(bool& truncated) noexcept {
  truncated = false;
  return 0;
}

fastfloat_really_inline
uint64_t uint64_hi64(uint64_t r0, bool& truncated) noexcept {
  truncated = false;
  int shl = leading_zeroes(r0);
  return r0 << shl;
}

fastfloat_really_inline
uint64_t uint64_hi64(uint64_t r0, uint64_t r1, bool& truncated) noexcept {
  int shl = leading_zeroes(r0);
  if (shl == 0) {
    truncated = r1 != 0;
    return r0;
  } else {
    int shr = 64 - shl;
    truncated = (r1 << shl) != 0;
    return (r0 << shl) | (r1 >> shr);
  }
}

fastfloat_really_inline
uint64_t uint32_hi64(uint32_t r0, bool& truncated) noexcept {
  return uint64_hi64(r0, truncated);
}

fastfloat_really_inline
uint64_t uint32_hi64(uint32_t r0, uint32_t r1, bool& truncated) noexcept {
  uint64_t x0 = r0;
  uint64_t x1 = r1;
  return uint64_hi64((x0 << 32) | x1, truncated);
}

fastfloat_really_inline
uint64_t uint32_hi64(uint32_t r0, uint32_t r1, uint32_t r2, bool& truncated) noexcept {
  uint64_t x0 = r0;
  uint64_t x1 = r1;
  uint64_t x2 = r2;
  return uint64_hi64(x0, (x1 << 32) | x2, truncated);
}

// add two small integers, checking for overflow.
// we want an efficient operation. for msvc, where
// we don't have built-in intrinsics, this is still
// pretty fast.
fastfloat_really_inline
limb scalar_add(limb x, limb y, bool& overflow) noexcept {
  limb z;

// gcc and clang
#if defined(__has_builtin)
  #if __has_builtin(__builtin_add_overflow)
    overflow = __builtin_add_overflow(x, y, &z);
    return z;
  #endif
#endif

  // generic, this still optimizes correctly on MSVC.
  z = x + y;
  overflow = z < x;
  return z;
}

// multiply two small integers, getting both the high and low bits.
fastfloat_really_inline
limb scalar_mul(limb x, limb y, limb& carry) noexcept {
#ifdef FASTFLOAT_64BIT_LIMB
  #if defined(__SIZEOF_INT128__)
  // GCC and clang both define it as an extension.
  __uint128_t z = __uint128_t(x) * __uint128_t(y) + __uint128_t(carry);
  carry = limb(z >> limb_bits);
  return limb(z);
  #else
  // fallback, no native 128-bit integer multiplication with carry.
  // on msvc, this optimizes identically, somehow.
  value128 z = full_multiplication(x, y);
  bool overflow;
  z.low = scalar_add(z.low, carry, overflow);
  z.high += uint64_t(overflow);  // cannot overflow
  carry = z.high;
  return z.low;
  #endif
#else
  uint64_t z = uint64_t(x) * uint64_t(y) + uint64_t(carry);
  carry = limb(z >> limb_bits);
  return limb(z);
#endif
}

// add scalar value to bigint starting from offset.
// used in grade school multiplication
template <uint16_t size>
inline bool small_add_from(stackvec<size>& vec, limb y, size_t start) noexcept {
  size_t index = start;
  limb carry = y;
  bool overflow;
  while (carry != 0 && index < vec.len()) {
    vec[index] = scalar_add(vec[index], carry, overflow);
    carry = limb(overflow);
    index += 1;
  }
  if (carry != 0) {
    FASTFLOAT_TRY(vec.try_push(carry));
  }
  return true;
}

// add scalar value to bigint.
template <uint16_t size>
fastfloat_really_inline bool small_add(stackvec<size>& vec, limb y) noexcept {
  return small_add_from(vec, y, 0);
}

// multiply bigint by scalar value.
template <uint16_t size>
inline bool small_mul(stackvec<size>& vec, limb y) noexcept {
  limb carry = 0;
  for (size_t index = 0; index < vec.len(); index++) {
    vec[index] = scalar_mul(vec[index], y, carry);
  }
  if (carry != 0) {
    FASTFLOAT_TRY(vec.try_push(carry));
  }
  return true;
}

// add bigint to bigint starting from index.
// used in grade school multiplication
template <uint16_t size>
bool large_add_from(stackvec<size>& x, limb_span y, size_t start) noexcept {
  // the effective x buffer is from `xstart..x.len()`, so exit early
  // if we can't get that current range.
  if (x.len() < start || y.len() > x.len() - start) {
      FASTFLOAT_TRY(x.try_resize(y.len() + start, 0));
  }

  bool carry = false;
  for (size_t index = 0; index < y.len(); index++) {
    limb xi = x[index + start];
    limb yi = y[index];
    bool c1 = false;
    bool c2 = false;
    xi = scalar_add(xi, yi, c1);
    if (carry) {
      xi = scalar_add(xi, 1, c2);
    }
    x[index + start] = xi;
    carry = c1 | c2;
  }

  // handle overflow
  if (carry) {
    FASTFLOAT_TRY(small_add_from(x, 1, y.len() + start));
  }
  return true;
}

// add bigint to bigint.
template <uint16_t size>
fastfloat_really_inline bool large_add_from(stackvec<size>& x, limb_span y) noexcept {
  return large_add_from(x, y, 0);
}

// grade-school multiplication algorithm
template <uint16_t size>
bool long_mul(stackvec<size>& x, limb_span y) noexcept {
  limb_span xs = limb_span(x.data, x.len());
  stackvec<size> z(xs);
  limb_span zs = limb_span(z.data, z.len());

  if (y.len() != 0) {
    limb y0 = y[0];
    FASTFLOAT_TRY(small_mul(x, y0));
    for (size_t index = 1; index < y.len(); index++) {
      limb yi = y[index];
      stackvec<size> zi;
      if (yi != 0) {
        // re-use the same buffer throughout
        zi.set_len(0);
        FASTFLOAT_TRY(zi.try_extend(zs));
        FASTFLOAT_TRY(small_mul(zi, yi));
        limb_span zis = limb_span(zi.data, zi.len());
        FASTFLOAT_TRY(large_add_from(x, zis, index));
      }
    }
  }

  x.normalize();
  return true;
}

// grade-school multiplication algorithm
template <uint16_t size>
bool large_mul(stackvec<size>& x, limb_span y) noexcept {
  if (y.len() == 1) {
    FASTFLOAT_TRY(small_mul(x, y[0]));
  } else {
    FASTFLOAT_TRY(long_mul(x, y));
  }
  return true;
}

// big integer type. implements a small subset of big integer
// arithmetic, using simple algorithms since asymptotically
// faster algorithms are slower for a small number of limbs.
// all operations assume the big-integer is normalized.
struct bigint {
  // storage of the limbs, in little-endian order.
  stackvec<bigint_limbs> vec;

  bigint(): vec() {}
  bigint(const bigint &) = delete;
  bigint &operator=(const bigint &) = delete;
  bigint(bigint &&) = delete;
  bigint &operator=(bigint &&other) = delete;

  bigint(uint64_t value): vec() {
#ifdef FASTFLOAT_64BIT_LIMB
    vec.push_unchecked(value);
#else
    vec.push_unchecked(uint32_t(value));
    vec.push_unchecked(uint32_t(value >> 32));
#endif
    vec.normalize();
  }

  // get the high 64 bits from the vector, and if bits were truncated.
  // this is to get the significant digits for the float.
  uint64_t hi64(bool& truncated) const noexcept {
#ifdef FASTFLOAT_64BIT_LIMB
    if (vec.len() == 0) {
      return empty_hi64(truncated);
    } else if (vec.len() == 1) {
      return uint64_hi64(vec.rindex(0), truncated);
    } else {
      uint64_t result = uint64_hi64(vec.rindex(0), vec.rindex(1), truncated);
      truncated |= vec.nonzero(2);
      return result;
    }
#else
    if (vec.len() == 0) {
      return empty_hi64(truncated);
    } else if (vec.len() == 1) {
      return uint32_hi64(vec.rindex(0), truncated);
    } else if (vec.len() == 2) {
      return uint32_hi64(vec.rindex(0), vec.rindex(1), truncated);
    } else {
      uint64_t result = uint32_hi64(vec.rindex(0), vec.rindex(1), vec.rindex(2), truncated);
      truncated |= vec.nonzero(3);
      return result;
    }
#endif
  }

  // compare two big integers, returning the large value.
  // assumes both are normalized. if the return value is
  // negative, other is larger, if the return value is
  // positive, this is larger, otherwise they are equal.
  // the limbs are stored in little-endian order, so we
  // must compare the limbs in ever order.
  int compare(const bigint& other) const noexcept {
    if (vec.len() > other.vec.len()) {
      return 1;
    } else if (vec.len() < other.vec.len()) {
      return -1;
    } else {
      for (size_t index = vec.len(); index > 0; index--) {
        limb xi = vec[index - 1];
        limb yi = other.vec[index - 1];
        if (xi > yi) {
          return 1;
        } else if (xi < yi) {
          return -1;
        }
      }
      return 0;
    }
  }

  // shift left each limb n bits, carrying over to the new limb
  // returns true if we were able to shift all the digits.
  bool shl_bits(size_t n) noexcept {
    // Internally, for each item, we shift left by n, and add the previous
    // right shifted limb-bits.
    // For example, we transform (for u8) shifted left 2, to:
    //      b10100100 b01000010
    //      b10 b10010001 b00001000
    FASTFLOAT_DEBUG_ASSERT(n != 0);
    FASTFLOAT_DEBUG_ASSERT(n < sizeof(limb) * 8);

    size_t shl = n;
    size_t shr = limb_bits - shl;
    limb prev = 0;
    for (size_t index = 0; index < vec.len(); index++) {
      limb xi = vec[index];
      vec[index] = (xi << shl) | (prev >> shr);
      prev = xi;
    }

    limb carry = prev >> shr;
    if (carry != 0) {
      return vec.try_push(carry);
    }
    return true;
  }

  // move the limbs left by `n` limbs.
  bool shl_limbs(size_t n) noexcept {
    FASTFLOAT_DEBUG_ASSERT(n != 0);
    if (n + vec.len() > vec.capacity()) {
      return false;
    } else if (!vec.is_empty()) {
      // move limbs
      limb* dst = vec.data + n;
      const limb* src = vec.data;
      ::memmove(dst, src, sizeof(limb) * vec.len());
      // fill in empty limbs
      limb* first = vec.data;
      limb* last = first + n;
      ::std::fill(first, last, 0);
      vec.set_len(n + vec.len());
      return true;
    } else {
      return true;
    }
  }

  // move the limbs left by `n` bits.
  bool shl(size_t n) noexcept {
    size_t rem = n % limb_bits;
    size_t div = n / limb_bits;
    if (rem != 0) {
      FASTFLOAT_TRY(shl_bits(rem));
    }
    if (div != 0) {
      FASTFLOAT_TRY(shl_limbs(div));
    }
    return true;
  }

  // get the number of leading zeros in the bigint.
  int ctlz() const noexcept {
    if (vec.is_empty()) {
      return 0;
    } else {
#ifdef FASTFLOAT_64BIT_LIMB
      return leading_zeroes(vec.rindex(0));
#else
      // no use defining a specialized leading_zeroes for a 32-bit type.
      uint64_t r0 = vec.rindex(0);
      return leading_zeroes(r0 << 32);
#endif
    }
  }

  // get the number of bits in the bigint.
  int bit_length() const noexcept {
    int lz = ctlz();
    return int(limb_bits * vec.len()) - lz;
  }

  bool mul(limb y) noexcept {
    return small_mul(vec, y);
  }

  bool add(limb y) noexcept {
    return small_add(vec, y);
  }

  // multiply as if by 2 raised to a power.
  bool pow2(uint32_t exp) noexcept {
    return shl(exp);
  }

  // multiply as if by 5 raised to a power.
  bool pow5(uint32_t exp) noexcept {
    // multiply by a power of 5
    static constexpr uint32_t large_step = 135;
    static constexpr uint64_t small_power_of_5[] = {
      1UL, 5UL, 25UL, 125UL, 625UL, 3125UL, 15625UL, 78125UL, 390625UL,
      1953125UL, 9765625UL, 48828125UL, 244140625UL, 1220703125UL,
      6103515625UL, 30517578125UL, 152587890625UL, 762939453125UL,
      3814697265625UL, 19073486328125UL, 95367431640625UL, 476837158203125UL,
      2384185791015625UL, 11920928955078125UL, 59604644775390625UL,
      298023223876953125UL, 1490116119384765625UL, 7450580596923828125UL,
    };
#ifdef FASTFLOAT_64BIT_LIMB
    constexpr static limb large_power_of_5[] = {
      1414648277510068013UL, 9180637584431281687UL, 4539964771860779200UL,
      10482974169319127550UL, 198276706040285095UL};
#else
    constexpr static limb large_power_of_5[] = {
      4279965485U, 329373468U, 4020270615U, 2137533757U, 4287402176U,
      1057042919U, 1071430142U, 2440757623U, 381945767U, 46164893U};
#endif
    size_t large_length = sizeof(large_power_of_5) / sizeof(limb);
    limb_span large = limb_span(large_power_of_5, large_length);
    while (exp >= large_step) {
      FASTFLOAT_TRY(large_mul(vec, large));
      exp -= large_step;
    }
#ifdef FASTFLOAT_64BIT_LIMB
    uint32_t small_step = 27;
    limb max_native = 7450580596923828125UL;
#else
    uint32_t small_step = 13;
    limb max_native = 1220703125U;
#endif
    while (exp >= small_step) {
      FASTFLOAT_TRY(small_mul(vec, max_native));
      exp -= small_step;
    }
    if (exp != 0) {
      FASTFLOAT_TRY(small_mul(vec, limb(small_power_of_5[exp])));
    }

    return true;
  }

  // multiply as if by 10 raised to a power.
  bool pow10(uint32_t exp) noexcept {
    FASTFLOAT_TRY(pow5(exp));
    return pow2(exp);
  }
};

} // namespace fast_float

#endif


#ifndef FASTFLOAT_ASCII_NUMBER_H
#define FASTFLOAT_ASCII_NUMBER_H

//included above:
//#include <cctype>
//included above:
//#include <cstdint>
//included above:
//#include <cstring>
//included above:
//#include <iterator>


namespace fast_float {

// Next function can be micro-optimized, but compilers are entirely
// able to optimize it well.
fastfloat_really_inline bool is_integer(char c)  noexcept  { return c >= '0' && c <= '9'; }

fastfloat_really_inline uint64_t byteswap(uint64_t val) {
  return (val & 0xFF00000000000000) >> 56
    | (val & 0x00FF000000000000) >> 40
    | (val & 0x0000FF0000000000) >> 24
    | (val & 0x000000FF00000000) >> 8
    | (val & 0x00000000FF000000) << 8
    | (val & 0x0000000000FF0000) << 24
    | (val & 0x000000000000FF00) << 40
    | (val & 0x00000000000000FF) << 56;
}

fastfloat_really_inline uint64_t read_u64(const char *chars) {
  uint64_t val;
  ::memcpy(&val, chars, sizeof(uint64_t));
#if FASTFLOAT_IS_BIG_ENDIAN == 1
  // Need to read as-if the number was in little-endian order.
  val = byteswap(val);
#endif
  return val;
}

fastfloat_really_inline void write_u64(uint8_t *chars, uint64_t val) {
#if FASTFLOAT_IS_BIG_ENDIAN == 1
  // Need to read as-if the number was in little-endian order.
  val = byteswap(val);
#endif
  ::memcpy(chars, &val, sizeof(uint64_t));
}

// credit  @aqrit
fastfloat_really_inline uint32_t  parse_eight_digits_unrolled(uint64_t val) {
  const uint64_t mask = 0x000000FF000000FF;
  const uint64_t mul1 = 0x000F424000000064; // 100 + (1000000ULL << 32)
  const uint64_t mul2 = 0x0000271000000001; // 1 + (10000ULL << 32)
  val -= 0x3030303030303030;
  val = (val * 10) + (val >> 8); // val = (val * 2561) >> 8;
  val = (((val & mask) * mul1) + (((val >> 16) & mask) * mul2)) >> 32;
  return uint32_t(val);
}

fastfloat_really_inline uint32_t parse_eight_digits_unrolled(const char *chars)  noexcept  {
  return parse_eight_digits_unrolled(read_u64(chars));
}

// credit @aqrit
fastfloat_really_inline bool is_made_of_eight_digits_fast(uint64_t val)  noexcept  {
  return !((((val + 0x4646464646464646) | (val - 0x3030303030303030)) &
     0x8080808080808080));
}

fastfloat_really_inline bool is_made_of_eight_digits_fast(const char *chars)  noexcept  {
  return is_made_of_eight_digits_fast(read_u64(chars));
}

typedef span<const char> byte_span;

struct parsed_number_string {
  int64_t exponent{0};
  uint64_t mantissa{0};
  const char *lastmatch{nullptr};
  bool negative{false};
  bool valid{false};
  bool too_many_digits{false};
  // contains the range of the significant digits
  byte_span integer{};  // non-nullable
  byte_span fraction{}; // nullable
};

// Assuming that you use no more than 19 digits, this will
// parse an ASCII string.
fastfloat_really_inline
parsed_number_string parse_number_string(const char *p, const char *pend, parse_options options) noexcept {
  const chars_format fmt = options.format;
  const char decimal_point = options.decimal_point;

  parsed_number_string answer;
  answer.valid = false;
  answer.too_many_digits = false;
  answer.negative = (*p == '-');
  if (*p == '-') { // C++17 20.19.3.(7.1) explicitly forbids '+' sign here
    ++p;
    if (p == pend) {
      return answer;
    }
    if (!is_integer(*p) && (*p != decimal_point)) { // a sign must be followed by an integer or the dot
      return answer;
    }
  }
  const char *const start_digits = p;

  uint64_t i = 0; // an unsigned int avoids signed overflows (which are bad)

  while ((std::distance(p, pend) >= 8) && is_made_of_eight_digits_fast(p)) {
    i = i * 100000000 + parse_eight_digits_unrolled(p); // in rare cases, this will overflow, but that's ok
    p += 8;
  }
  while ((p != pend) && is_integer(*p)) {
    // a multiplication by 10 is cheaper than an arbitrary integer
    // multiplication
    i = 10 * i +
        uint64_t(*p - '0'); // might overflow, we will handle the overflow later
    ++p;
  }
  const char *const end_of_integer_part = p;
  int64_t digit_count = int64_t(end_of_integer_part - start_digits);
  answer.integer = byte_span(start_digits, size_t(digit_count));
  int64_t exponent = 0;
  if ((p != pend) && (*p == decimal_point)) {
    ++p;
    const char* before = p;
    // can occur at most twice without overflowing, but let it occur more, since
    // for integers with many digits, digit parsing is the primary bottleneck.
    while ((std::distance(p, pend) >= 8) && is_made_of_eight_digits_fast(p)) {
      i = i * 100000000 + parse_eight_digits_unrolled(p); // in rare cases, this will overflow, but that's ok
      p += 8;
    }
    while ((p != pend) && is_integer(*p)) {
      uint8_t digit = uint8_t(*p - '0');
      ++p;
      i = i * 10 + digit; // in rare cases, this will overflow, but that's ok
    }
    exponent = before - p;
    answer.fraction = byte_span(before, size_t(p - before));
    digit_count -= exponent;
  }
  // we must have encountered at least one integer!
  if (digit_count == 0) {
    return answer;
  }
  int64_t exp_number = 0;            // explicit exponential part
  if ((fmt & chars_format::scientific) && (p != pend) && (('e' == *p) || ('E' == *p))) {
    const char * location_of_e = p;
    ++p;
    bool neg_exp = false;
    if ((p != pend) && ('-' == *p)) {
      neg_exp = true;
      ++p;
    } else if ((p != pend) && ('+' == *p)) { // '+' on exponent is allowed by C++17 20.19.3.(7.1)
      ++p;
    }
    if ((p == pend) || !is_integer(*p)) {
      if(!(fmt & chars_format::fixed)) {
        // We are in error.
        return answer;
      }
      // Otherwise, we will be ignoring the 'e'.
      p = location_of_e;
    } else {
      while ((p != pend) && is_integer(*p)) {
        uint8_t digit = uint8_t(*p - '0');
        if (exp_number < 0x10000000) {
          exp_number = 10 * exp_number + digit;
        }
        ++p;
      }
      if(neg_exp) { exp_number = - exp_number; }
      exponent += exp_number;
    }
  } else {
    // If it scientific and not fixed, we have to bail out.
    if((fmt & chars_format::scientific) && !(fmt & chars_format::fixed)) { return answer; }
  }
  answer.lastmatch = p;
  answer.valid = true;

  // If we frequently had to deal with long strings of digits,
  // we could extend our code by using a 128-bit integer instead
  // of a 64-bit integer. However, this is uncommon.
  //
  // We can deal with up to 19 digits.
  if (digit_count > 19) { // this is uncommon
    // It is possible that the integer had an overflow.
    // We have to handle the case where we have 0.0000somenumber.
    // We need to be mindful of the case where we only have zeroes...
    // E.g., 0.000000000...000.
    const char *start = start_digits;
    while ((start != pend) && (*start == '0' || *start == decimal_point)) {
      if(*start == '0') { digit_count --; }
      start++;
    }
    if (digit_count > 19) {
      answer.too_many_digits = true;
      // Let us start again, this time, avoiding overflows.
      // We don't need to check if is_integer, since we use the
      // pre-tokenized spans from above.
      i = 0;
      p = answer.integer.ptr;
      const char* int_end = p + answer.integer.len();
      const uint64_t minimal_nineteen_digit_integer{1000000000000000000};
      while((i < minimal_nineteen_digit_integer) && (p != int_end)) {
        i = i * 10 + uint64_t(*p - '0');
        ++p;
      }
      if (i >= minimal_nineteen_digit_integer) { // We have a big integers
        exponent = end_of_integer_part - p + exp_number;
      } else { // We have a value with a fractional component.
          p = answer.fraction.ptr;
          const char* frac_end = p + answer.fraction.len();
          while((i < minimal_nineteen_digit_integer) && (p != frac_end)) {
            i = i * 10 + uint64_t(*p - '0');
            ++p;
          }
          exponent = answer.fraction.ptr - p + exp_number;
      }
      // We have now corrected both exponent and i, to a truncated value
    }
  }
  answer.exponent = exponent;
  answer.mantissa = i;
  return answer;
}

} // namespace fast_float

#endif


#ifndef FASTFLOAT_DIGIT_COMPARISON_H
#define FASTFLOAT_DIGIT_COMPARISON_H

//included above:
//#include <algorithm>
//included above:
//#include <cstdint>
//included above:
//#include <cstring>
//included above:
//#include <iterator>


namespace fast_float {

// 1e0 to 1e19
constexpr static uint64_t powers_of_ten_uint64[] = {
    1UL, 10UL, 100UL, 1000UL, 10000UL, 100000UL, 1000000UL, 10000000UL, 100000000UL,
    1000000000UL, 10000000000UL, 100000000000UL, 1000000000000UL, 10000000000000UL,
    100000000000000UL, 1000000000000000UL, 10000000000000000UL, 100000000000000000UL,
    1000000000000000000UL, 10000000000000000000UL};

// calculate the exponent, in scientific notation, of the number.
// this algorithm is not even close to optimized, but it has no practical
// effect on performance: in order to have a faster algorithm, we'd need
// to slow down performance for faster algorithms, and this is still fast.
fastfloat_really_inline int32_t scientific_exponent(parsed_number_string& num) noexcept {
  uint64_t mantissa = num.mantissa;
  int32_t exponent = int32_t(num.exponent);
  while (mantissa >= 10000) {
    mantissa /= 10000;
    exponent += 4;
  }
  while (mantissa >= 100) {
    mantissa /= 100;
    exponent += 2;
  }
  while (mantissa >= 10) {
    mantissa /= 10;
    exponent += 1;
  }
  return exponent;
}

// this converts a native floating-point number to an extended-precision float.
template <typename T>
fastfloat_really_inline adjusted_mantissa to_extended(T value) noexcept {
  adjusted_mantissa am;
  int32_t bias = binary_format<T>::mantissa_explicit_bits() - binary_format<T>::minimum_exponent();
  if (std::is_same<T, float>::value) {
    constexpr uint32_t exponent_mask = 0x7F800000;
    constexpr uint32_t mantissa_mask = 0x007FFFFF;
    constexpr uint64_t hidden_bit_mask = 0x00800000;
    uint32_t bits;
    ::memcpy(&bits, &value, sizeof(T));
    if ((bits & exponent_mask) == 0) {
      // denormal
      am.power2 = 1 - bias;
      am.mantissa = bits & mantissa_mask;
    } else {
      // normal
      am.power2 = int32_t((bits & exponent_mask) >> binary_format<T>::mantissa_explicit_bits());
      am.power2 -= bias;
      am.mantissa = (bits & mantissa_mask) | hidden_bit_mask;
    }
  } else {
    constexpr uint64_t exponent_mask = 0x7FF0000000000000;
    constexpr uint64_t mantissa_mask = 0x000FFFFFFFFFFFFF;
    constexpr uint64_t hidden_bit_mask = 0x0010000000000000;
    uint64_t bits;
    ::memcpy(&bits, &value, sizeof(T));
    if ((bits & exponent_mask) == 0) {
      // denormal
      am.power2 = 1 - bias;
      am.mantissa = bits & mantissa_mask;
    } else {
      // normal
      am.power2 = int32_t((bits & exponent_mask) >> binary_format<T>::mantissa_explicit_bits());
      am.power2 -= bias;
      am.mantissa = (bits & mantissa_mask) | hidden_bit_mask;
    }
  }

  return am;
}

// get the extended precision value of the halfway point between b and b+u.
// we are given a native float that represents b, so we need to adjust it
// halfway between b and b+u.
template <typename T>
fastfloat_really_inline adjusted_mantissa to_extended_halfway(T value) noexcept {
  adjusted_mantissa am = to_extended(value);
  am.mantissa <<= 1;
  am.mantissa += 1;
  am.power2 -= 1;
  return am;
}

// round an extended-precision float to the nearest machine float.
template <typename T, typename callback>
fastfloat_really_inline void round(adjusted_mantissa& am, callback cb) noexcept {
  int32_t mantissa_shift = 64 - binary_format<T>::mantissa_explicit_bits() - 1;
  if (-am.power2 >= mantissa_shift) {
    // have a denormal float
    int32_t shift = -am.power2 + 1;
    cb(am, std::min(shift, 64));
    // check for round-up: if rounding-nearest carried us to the hidden bit.
    am.power2 = (am.mantissa < (uint64_t(1) << binary_format<T>::mantissa_explicit_bits())) ? 0 : 1;
    return;
  }

  // have a normal float, use the default shift.
  cb(am, mantissa_shift);

  // check for carry
  if (am.mantissa >= (uint64_t(2) << binary_format<T>::mantissa_explicit_bits())) {
    am.mantissa = (uint64_t(1) << binary_format<T>::mantissa_explicit_bits());
    am.power2++;
  }

  // check for infinite: we could have carried to an infinite power
  am.mantissa &= ~(uint64_t(1) << binary_format<T>::mantissa_explicit_bits());
  if (am.power2 >= binary_format<T>::infinite_power()) {
    am.power2 = binary_format<T>::infinite_power();
    am.mantissa = 0;
  }
}

template <typename callback>
fastfloat_really_inline
void round_nearest_tie_even(adjusted_mantissa& am, int32_t shift, callback cb) noexcept {
  uint64_t mask;
  uint64_t halfway;
  if (shift == 64) {
    mask = UINT64_MAX;
  } else {
    mask = (uint64_t(1) << shift) - 1;
  }
  if (shift == 0) {
    halfway = 0;
  } else {
    halfway = uint64_t(1) << (shift - 1);
  }
  uint64_t truncated_bits = am.mantissa & mask;
  uint64_t is_above = truncated_bits > halfway;
  uint64_t is_halfway = truncated_bits == halfway;

  // shift digits into position
  if (shift == 64) {
    am.mantissa = 0;
  } else {
    am.mantissa >>= shift;
  }
  am.power2 += shift;

  bool is_odd = (am.mantissa & 1) == 1;
  am.mantissa += uint64_t(cb(is_odd, is_halfway, is_above));
}

fastfloat_really_inline void round_down(adjusted_mantissa& am, int32_t shift) noexcept {
  if (shift == 64) {
    am.mantissa = 0;
  } else {
    am.mantissa >>= shift;
  }
  am.power2 += shift;
}

fastfloat_really_inline void skip_zeros(const char*& first, const char* last) noexcept {
  uint64_t val;
  while (std::distance(first, last) >= 8) {
    ::memcpy(&val, first, sizeof(uint64_t));
    if (val != 0x3030303030303030) {
      break;
    }
    first += 8;
  }
  while (first != last) {
    if (*first != '0') {
      break;
    }
    first++;
  }
}

// determine if any non-zero digits were truncated.
// all characters must be valid digits.
fastfloat_really_inline bool is_truncated(const char* first, const char* last) noexcept {
  // do 8-bit optimizations, can just compare to 8 literal 0s.
  uint64_t val;
  while (std::distance(first, last) >= 8) {
    ::memcpy(&val, first, sizeof(uint64_t));
    if (val != 0x3030303030303030) {
      return true;
    }
    first += 8;
  }
  while (first != last) {
    if (*first != '0') {
      return true;
    }
    first++;
  }
  return false;
}

fastfloat_really_inline bool is_truncated(byte_span s) noexcept {
  return is_truncated(s.ptr, s.ptr + s.len());
}

fastfloat_really_inline
void parse_eight_digits(const char*& p, limb& value, size_t& counter, size_t& count) noexcept {
  value = value * 100000000 + parse_eight_digits_unrolled(p);
  p += 8;
  counter += 8;
  count += 8;
}

fastfloat_really_inline
void parse_one_digit(const char*& p, limb& value, size_t& counter, size_t& count) noexcept {
  value = value * 10 + limb(*p - '0');
  p++;
  counter++;
  count++;
}

fastfloat_really_inline
void add_native(bigint& big, limb power, limb value) noexcept {
  big.mul(power);
  big.add(value);
}

fastfloat_really_inline void round_up_bigint(bigint& big, size_t& count) noexcept {
  // need to round-up the digits, but need to avoid rounding
  // ....9999 to ...10000, which could cause a false halfway point.
  add_native(big, 10, 1);
  count++;
}

// parse the significant digits into a big integer
inline void parse_mantissa(bigint& result, parsed_number_string& num, size_t max_digits, size_t& digits) noexcept {
  // try to minimize the number of big integer and scalar multiplication.
  // therefore, try to parse 8 digits at a time, and multiply by the largest
  // scalar value (9 or 19 digits) for each step.
  size_t counter = 0;
  digits = 0;
  limb value = 0;
#ifdef FASTFLOAT_64BIT_LIMB
  size_t step = 19;
#else
  size_t step = 9;
#endif

  // process all integer digits.
  const char* p = num.integer.ptr;
  const char* pend = p + num.integer.len();
  skip_zeros(p, pend);
  // process all digits, in increments of step per loop
  while (p != pend) {
    while ((std::distance(p, pend) >= 8) && (step - counter >= 8) && (max_digits - digits >= 8)) {
      parse_eight_digits(p, value, counter, digits);
    }
    while (counter < step && p != pend && digits < max_digits) {
      parse_one_digit(p, value, counter, digits);
    }
    if (digits == max_digits) {
      // add the temporary value, then check if we've truncated any digits
      add_native(result, limb(powers_of_ten_uint64[counter]), value);
      bool truncated = is_truncated(p, pend);
      if (num.fraction.ptr != nullptr) {
        truncated |= is_truncated(num.fraction);
      }
      if (truncated) {
        round_up_bigint(result, digits);
      }
      return;
    } else {
      add_native(result, limb(powers_of_ten_uint64[counter]), value);
      counter = 0;
      value = 0;
    }
  }

  // add our fraction digits, if they're available.
  if (num.fraction.ptr != nullptr) {
    p = num.fraction.ptr;
    pend = p + num.fraction.len();
    if (digits == 0) {
      skip_zeros(p, pend);
    }
    // process all digits, in increments of step per loop
    while (p != pend) {
      while ((std::distance(p, pend) >= 8) && (step - counter >= 8) && (max_digits - digits >= 8)) {
        parse_eight_digits(p, value, counter, digits);
      }
      while (counter < step && p != pend && digits < max_digits) {
        parse_one_digit(p, value, counter, digits);
      }
      if (digits == max_digits) {
        // add the temporary value, then check if we've truncated any digits
        add_native(result, limb(powers_of_ten_uint64[counter]), value);
        bool truncated = is_truncated(p, pend);
        if (truncated) {
          round_up_bigint(result, digits);
        }
        return;
      } else {
        add_native(result, limb(powers_of_ten_uint64[counter]), value);
        counter = 0;
        value = 0;
      }
    }
  }

  if (counter != 0) {
    add_native(result, limb(powers_of_ten_uint64[counter]), value);
  }
}

template <typename T>
inline adjusted_mantissa positive_digit_comp(bigint& bigmant, int32_t exponent) noexcept {
  FASTFLOAT_ASSERT(bigmant.pow10(uint32_t(exponent)));
  adjusted_mantissa answer;
  bool truncated;
  answer.mantissa = bigmant.hi64(truncated);
  int bias = binary_format<T>::mantissa_explicit_bits() - binary_format<T>::minimum_exponent();
  answer.power2 = bigmant.bit_length() - 64 + bias;

  round<T>(answer, [truncated](adjusted_mantissa& a, int32_t shift) {
    round_nearest_tie_even(a, shift, [truncated](bool is_odd, bool is_halfway, bool is_above) -> bool {
      return is_above || (is_halfway && truncated) || (is_odd && is_halfway);
    });
  });

  return answer;
}

// the scaling here is quite simple: we have, for the real digits `m * 10^e`,
// and for the theoretical digits `n * 2^f`. Since `e` is always negative,
// to scale them identically, we do `n * 2^f * 5^-f`, so we now have `m * 2^e`.
// we then need to scale by `2^(f- e)`, and then the two significant digits
// are of the same magnitude.
template <typename T>
inline adjusted_mantissa negative_digit_comp(bigint& bigmant, adjusted_mantissa am, int32_t exponent) noexcept {
  bigint& real_digits = bigmant;
  int32_t real_exp = exponent;

  // get the value of `b`, rounded down, and get a bigint representation of b+h
  adjusted_mantissa am_b = am;
  // gcc7 buf: use a lambda to remove the noexcept qualifier bug with -Wnoexcept-type.
  round<T>(am_b, [](adjusted_mantissa&a, int32_t shift) { round_down(a, shift); });
  T b;
  to_float(false, am_b, b);
  adjusted_mantissa theor = to_extended_halfway(b);
  bigint theor_digits(theor.mantissa);
  int32_t theor_exp = theor.power2;

  // scale real digits and theor digits to be same power.
  int32_t pow2_exp = theor_exp - real_exp;
  uint32_t pow5_exp = uint32_t(-real_exp);
  if (pow5_exp != 0) {
    FASTFLOAT_ASSERT(theor_digits.pow5(pow5_exp));
  }
  if (pow2_exp > 0) {
    FASTFLOAT_ASSERT(theor_digits.pow2(uint32_t(pow2_exp)));
  } else if (pow2_exp < 0) {
    FASTFLOAT_ASSERT(real_digits.pow2(uint32_t(-pow2_exp)));
  }

  // compare digits, and use it to director rounding
  int ord = real_digits.compare(theor_digits);
  adjusted_mantissa answer = am;
  round<T>(answer, [ord](adjusted_mantissa& a, int32_t shift) {
    round_nearest_tie_even(a, shift, [ord](bool is_odd, bool _, bool __) -> bool {
      (void)_;  // not needed, since we've done our comparison
      (void)__; // not needed, since we've done our comparison
      if (ord > 0) {
        return true;
      } else if (ord < 0) {
        return false;
      } else {
        return is_odd;
      }
    });
  });

  return answer;
}

// parse the significant digits as a big integer to unambiguously round the
// the significant digits. here, we are trying to determine how to round
// an extended float representation close to `b+h`, halfway between `b`
// (the float rounded-down) and `b+u`, the next positive float. this
// algorithm is always correct, and uses one of two approaches. when
// the exponent is positive relative to the significant digits (such as
// 1234), we create a big-integer representation, get the high 64-bits,
// determine if any lower bits are truncated, and use that to direct
// rounding. in case of a negative exponent relative to the significant
// digits (such as 1.2345), we create a theoretical representation of
// `b` as a big-integer type, scaled to the same binary exponent as
// the actual digits. we then compare the big integer representations
// of both, and use that to direct rounding.
template <typename T>
inline adjusted_mantissa digit_comp(parsed_number_string& num, adjusted_mantissa am) noexcept {
  // remove the invalid exponent bias
  am.power2 -= invalid_am_bias;

  int32_t sci_exp = scientific_exponent(num);
  size_t max_digits = binary_format<T>::max_digits();
  size_t digits = 0;
  bigint bigmant;
  parse_mantissa(bigmant, num, max_digits, digits);
  // can't underflow, since digits is at most max_digits.
  int32_t exponent = sci_exp + 1 - int32_t(digits);
  if (exponent >= 0) {
    return positive_digit_comp<T>(bigmant, exponent);
  } else {
    return negative_digit_comp<T>(bigmant, am, exponent);
  }
}

} // namespace fast_float

#endif


#ifndef FASTFLOAT_PARSE_NUMBER_H
#define FASTFLOAT_PARSE_NUMBER_H


//included above:
//#include <cmath>
//included above:
//#include <cstring>
//included above:
//#include <limits>
//included above:
//#include <system_error>

namespace fast_float {


namespace detail {
/**
 * Special case +inf, -inf, nan, infinity, -infinity.
 * The case comparisons could be made much faster given that we know that the
 * strings a null-free and fixed.
 **/
template <typename T>
from_chars_result parse_infnan(const char *first, const char *last, T &value)  noexcept  {
  from_chars_result answer;
  answer.ptr = first;
  answer.ec = std::errc(); // be optimistic
  bool minusSign = false;
  if (*first == '-') { // assume first < last, so dereference without checks; C++17 20.19.3.(7.1) explicitly forbids '+' here
      minusSign = true;
      ++first;
  }
  if (last - first >= 3) {
    if (fastfloat_strncasecmp(first, "nan", 3)) {
      answer.ptr = (first += 3);
      value = minusSign ? -std::numeric_limits<T>::quiet_NaN() : std::numeric_limits<T>::quiet_NaN();
      // Check for possible nan(n-char-seq-opt), C++17 20.19.3.7, C11 7.20.1.3.3. At least MSVC produces nan(ind) and nan(snan).
      if(first != last && *first == '(') {
        for(const char* ptr = first + 1; ptr != last; ++ptr) {
          if (*ptr == ')') {
            answer.ptr = ptr + 1; // valid nan(n-char-seq-opt)
            break;
          }
          else if(!(('a' <= *ptr && *ptr <= 'z') || ('A' <= *ptr && *ptr <= 'Z') || ('0' <= *ptr && *ptr <= '9') || *ptr == '_'))
            break; // forbidden char, not nan(n-char-seq-opt)
        }
      }
      return answer;
    }
    if (fastfloat_strncasecmp(first, "inf", 3)) {
      if ((last - first >= 8) && fastfloat_strncasecmp(first + 3, "inity", 5)) {
        answer.ptr = first + 8;
      } else {
        answer.ptr = first + 3;
      }
      value = minusSign ? -std::numeric_limits<T>::infinity() : std::numeric_limits<T>::infinity();
      return answer;
    }
  }
  answer.ec = std::errc::invalid_argument;
  return answer;
}

} // namespace detail

template<typename T>
from_chars_result from_chars(const char *first, const char *last,
                             T &value, chars_format fmt /*= chars_format::general*/)  noexcept  {
  return from_chars_advanced(first, last, value, parse_options{fmt});
}

template<typename T>
from_chars_result from_chars_advanced(const char *first, const char *last,
                                      T &value, parse_options options)  noexcept  {

  static_assert (std::is_same<T, double>::value || std::is_same<T, float>::value, "only float and double are supported");


  from_chars_result answer;
  if (first == last) {
    answer.ec = std::errc::invalid_argument;
    answer.ptr = first;
    return answer;
  }
  parsed_number_string pns = parse_number_string(first, last, options);
  if (!pns.valid) {
    return detail::parse_infnan(first, last, value);
  }
  answer.ec = std::errc(); // be optimistic
  answer.ptr = pns.lastmatch;
  // Next is Clinger's fast path.
  if (binary_format<T>::min_exponent_fast_path() <= pns.exponent && pns.exponent <= binary_format<T>::max_exponent_fast_path() && pns.mantissa <=binary_format<T>::max_mantissa_fast_path() && !pns.too_many_digits) {
    value = T(pns.mantissa);
    if (pns.exponent < 0) { value = value / binary_format<T>::exact_power_of_ten(-pns.exponent); }
    else { value = value * binary_format<T>::exact_power_of_ten(pns.exponent); }
    if (pns.negative) { value = -value; }
    return answer;
  }
  adjusted_mantissa am = compute_float<binary_format<T>>(pns.exponent, pns.mantissa);
  if(pns.too_many_digits && am.power2 >= 0) {
    if(am != compute_float<binary_format<T>>(pns.exponent, pns.mantissa + 1)) {
      am = compute_error<binary_format<T>>(pns.exponent, pns.mantissa);
    }
  }
  // If we called compute_float<binary_format<T>>(pns.exponent, pns.mantissa) and we have an invalid power (am.power2 < 0),
  // then we need to go the long way around again. This is very uncommon.
  if(am.power2 < 0) { am = digit_comp<T>(pns, am); }
  to_float(pns.negative, am, value);
  return answer;
}

} // namespace fast_float

#endif

#ifdef _MSC_VER
#   pragma warning(pop)
#elif defined(__clang__) || defined(__APPLE_CC__)
#   pragma clang diagnostic pop
#elif defined(__GNUC__)
#   pragma GCC diagnostic pop
#endif

#endif // _C4_EXT_FAST_FLOAT_HPP_


// (end https://github.com/biojppm/c4core/src/c4/ext/fast_float.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/std/vector_fwd.hpp
// https://github.com/biojppm/c4core/src/c4/std/vector_fwd.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_STD_VECTOR_FWD_HPP_
#define _C4_STD_VECTOR_FWD_HPP_

/** @file vector_fwd.hpp */

//included above:
//#include <cstddef>

// forward declarations for std::vector
#if defined(__GLIBCXX__) || defined(__GLIBCPP__) || defined(_MSC_VER)
#if defined(_MSC_VER)
__pragma(warning(push))
__pragma(warning(disable : 4643))
#endif
namespace std {
template<typename> class allocator;
template<typename T, typename Alloc> class vector;
} // namespace std
#if defined(_MSC_VER)
__pragma(warning(pop))
#endif
#elif defined(_LIBCPP_ABI_NAMESPACE)
namespace std {
inline namespace _LIBCPP_ABI_NAMESPACE {
template<typename> class allocator;
template<typename T, typename Alloc> class vector;
} // namespace _LIBCPP_ABI_NAMESPACE
} // namespace std
#else
#error "unknown standard library"
#endif

#ifndef C4CORE_SINGLE_HEADER
// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/substr_fwd.hpp
//#include "c4/substr_fwd.hpp"
#if !defined(C4_SUBSTR_FWD_HPP_) && !defined(_C4_SUBSTR_FWD_HPP_)
#error "amalgamate: file c4/substr_fwd.hpp must have been included at this point"
#endif /* C4_SUBSTR_FWD_HPP_ */

#endif

namespace c4 {

template<class Alloc> c4::substr to_substr(std::vector<char, Alloc> &vec);
template<class Alloc> c4::csubstr to_csubstr(std::vector<char, Alloc> const& vec);

template<class Alloc> bool operator!= (c4::csubstr ss, std::vector<char, Alloc> const& s);
template<class Alloc> bool operator== (c4::csubstr ss, std::vector<char, Alloc> const& s);
template<class Alloc> bool operator>= (c4::csubstr ss, std::vector<char, Alloc> const& s);
template<class Alloc> bool operator>  (c4::csubstr ss, std::vector<char, Alloc> const& s);
template<class Alloc> bool operator<= (c4::csubstr ss, std::vector<char, Alloc> const& s);
template<class Alloc> bool operator<  (c4::csubstr ss, std::vector<char, Alloc> const& s);

template<class Alloc> bool operator!= (std::vector<char, Alloc> const& s, c4::csubstr ss);
template<class Alloc> bool operator== (std::vector<char, Alloc> const& s, c4::csubstr ss);
template<class Alloc> bool operator>= (std::vector<char, Alloc> const& s, c4::csubstr ss);
template<class Alloc> bool operator>  (std::vector<char, Alloc> const& s, c4::csubstr ss);
template<class Alloc> bool operator<= (std::vector<char, Alloc> const& s, c4::csubstr ss);
template<class Alloc> bool operator<  (std::vector<char, Alloc> const& s, c4::csubstr ss);

template<class Alloc> size_t to_chars(c4::substr buf, std::vector<char, Alloc> const& s);
template<class Alloc> bool from_chars(c4::csubstr buf, std::vector<char, Alloc> * s);

} // namespace c4

#endif // _C4_STD_VECTOR_FWD_HPP_


// (end https://github.com/biojppm/c4core/src/c4/std/vector_fwd.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/std/string_fwd.hpp
// https://github.com/biojppm/c4core/src/c4/std/string_fwd.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_STD_STRING_FWD_HPP_
#define _C4_STD_STRING_FWD_HPP_

/** @file string_fwd.hpp */

#ifndef DOXYGEN

#ifndef C4CORE_SINGLE_HEADER
// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/substr_fwd.hpp
//#include "c4/substr_fwd.hpp"
#if !defined(C4_SUBSTR_FWD_HPP_) && !defined(_C4_SUBSTR_FWD_HPP_)
#error "amalgamate: file c4/substr_fwd.hpp must have been included at this point"
#endif /* C4_SUBSTR_FWD_HPP_ */

#endif

//included above:
//#include <cstddef>

// forward declarations for std::string
#if defined(__GLIBCXX__) || defined(__GLIBCPP__)
#include <bits/stringfwd.h>  // use the fwd header in glibcxx
#elif defined(_LIBCPP_VERSION) || defined(__APPLE_CC__)
#include <iosfwd>  // use the fwd header in stdlibc++
#elif defined(_MSC_VER)
//! @todo is there a fwd header in msvc?
namespace std {
template<typename> struct char_traits;
template<typename> class allocator;
template<typename _CharT, typename _Traits, typename _Alloc> class basic_string;
using string = basic_string<char, char_traits<char>, allocator<char>>;
} /* namespace std */
#else
#error "unknown standard library"
#endif

namespace c4 {

C4_ALWAYS_INLINE c4::substr to_substr(std::string &s) noexcept;
C4_ALWAYS_INLINE c4::csubstr to_csubstr(std::string const& s) noexcept;

bool operator== (c4::csubstr ss, std::string const& s);
bool operator!= (c4::csubstr ss, std::string const& s);
bool operator>= (c4::csubstr ss, std::string const& s);
bool operator>  (c4::csubstr ss, std::string const& s);
bool operator<= (c4::csubstr ss, std::string const& s);
bool operator<  (c4::csubstr ss, std::string const& s);

bool operator== (std::string const& s, c4::csubstr ss);
bool operator!= (std::string const& s, c4::csubstr ss);
bool operator>= (std::string const& s, c4::csubstr ss);
bool operator>  (std::string const& s, c4::csubstr ss);
bool operator<= (std::string const& s, c4::csubstr ss);
bool operator<  (std::string const& s, c4::csubstr ss);

size_t to_chars(c4::substr buf, std::string const& s);
bool from_chars(c4::csubstr buf, std::string * s);

} // namespace c4

#endif // DOXYGEN
#endif // _C4_STD_STRING_FWD_HPP_


// (end https://github.com/biojppm/c4core/src/c4/std/string_fwd.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/std/std_fwd.hpp
// https://github.com/biojppm/c4core/src/c4/std/std_fwd.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_STD_STD_FWD_HPP_
#define _C4_STD_STD_FWD_HPP_

/** @file std_fwd.hpp includes all c4-std interop fwd files */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/std/vector_fwd.hpp
//#include "c4/std/vector_fwd.hpp"
#if !defined(C4_STD_VECTOR_FWD_HPP_) && !defined(_C4_STD_VECTOR_FWD_HPP_)
#error "amalgamate: file c4/std/vector_fwd.hpp must have been included at this point"
#endif /* C4_STD_VECTOR_FWD_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/std/string_fwd.hpp
//#include "c4/std/string_fwd.hpp"
#if !defined(C4_STD_STRING_FWD_HPP_) && !defined(_C4_STD_STRING_FWD_HPP_)
#error "amalgamate: file c4/std/string_fwd.hpp must have been included at this point"
#endif /* C4_STD_STRING_FWD_HPP_ */

//#include "c4/std/tuple_fwd.hpp"

#endif // _C4_STD_STD_FWD_HPP_


// (end https://github.com/biojppm/c4core/src/c4/std/std_fwd.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/charconv.hpp
// https://github.com/biojppm/c4core/src/c4/charconv.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_CHARCONV_HPP_
#define _C4_CHARCONV_HPP_

/** @file charconv.hpp Lightweight generic type-safe wrappers for
 * converting individual values to/from strings.
 *
 * These are the main functions:
 *
 * @code{.cpp}
 * // Convert the given value, writing into the string.
 * // The resulting string will NOT be null-terminated.
 * // Return the number of characters needed.
 * // This function is safe to call when the string is too small -
 * // no writes will occur beyond the string's last character.
 * template<class T> size_t c4::to_chars(substr buf, T const& C4_RESTRICT val);
 *
 *
 * // Convert the given value to a string using to_chars(), and
 * // return the resulting string, up to and including the last
 * // written character.
 * template<class T> substr c4::to_chars_sub(substr buf, T const& C4_RESTRICT val);
 *
 *
 * // Read a value from the string, which must be
 * // trimmed to the value (ie, no leading/trailing whitespace).
 * // return true if the conversion succeeded.
 * // There is no check for overflow; the value wraps around in a way similar
 * // to the standard C/C++ overflow behavior. For example,
 * // from_chars<int8_t>("128", &val) returns true and val will be
 * // set tot 0.
 * template<class T> bool c4::from_chars(csubstr buf, T * C4_RESTRICT val);
 *
 *
 * // Read the first valid sequence of characters from the string,
 * // skipping leading whitespace, and convert it using from_chars().
 * // Return the number of characters read for converting.
 * template<class T> size_t c4::from_chars_first(csubstr buf, T * C4_RESTRICT val);
 * @endcode
 */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/language.hpp
//#include "c4/language.hpp"
#if !defined(C4_LANGUAGE_HPP_) && !defined(_C4_LANGUAGE_HPP_)
#error "amalgamate: file c4/language.hpp must have been included at this point"
#endif /* C4_LANGUAGE_HPP_ */

//included above:
//#include <inttypes.h>
//included above:
//#include <type_traits>
//included above:
//#include <climits>
//included above:
//#include <limits>
//included above:
//#include <utility>

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/config.hpp
//#include "c4/config.hpp"
#if !defined(C4_CONFIG_HPP_) && !defined(_C4_CONFIG_HPP_)
#error "amalgamate: file c4/config.hpp must have been included at this point"
#endif /* C4_CONFIG_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/substr.hpp
//#include "c4/substr.hpp"
#if !defined(C4_SUBSTR_HPP_) && !defined(_C4_SUBSTR_HPP_)
#error "amalgamate: file c4/substr.hpp must have been included at this point"
#endif /* C4_SUBSTR_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/std/std_fwd.hpp
//#include "c4/std/std_fwd.hpp"
#if !defined(C4_STD_STD_FWD_HPP_) && !defined(_C4_STD_STD_FWD_HPP_)
#error "amalgamate: file c4/std/std_fwd.hpp must have been included at this point"
#endif /* C4_STD_STD_FWD_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/memory_util.hpp
//#include "c4/memory_util.hpp"
#if !defined(C4_MEMORY_UTIL_HPP_) && !defined(_C4_MEMORY_UTIL_HPP_)
#error "amalgamate: file c4/memory_util.hpp must have been included at this point"
#endif /* C4_MEMORY_UTIL_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/szconv.hpp
//#include "c4/szconv.hpp"
#if !defined(C4_SZCONV_HPP_) && !defined(_C4_SZCONV_HPP_)
#error "amalgamate: file c4/szconv.hpp must have been included at this point"
#endif /* C4_SZCONV_HPP_ */


#ifndef C4CORE_NO_FAST_FLOAT
#   if (C4_CPP >= 17)
#       if defined(_MSC_VER)
#           if (C4_MSVC_VERSION >= C4_MSVC_VERSION_2019) // VS2017 and lower do not have these macros
#               include <charconv>
#               define C4CORE_HAVE_STD_TOCHARS 1
#               define C4CORE_HAVE_STD_FROMCHARS 0 // prefer fast_float with MSVC
#               define C4CORE_HAVE_FAST_FLOAT 1
#           else
#               define C4CORE_HAVE_STD_TOCHARS 0
#               define C4CORE_HAVE_STD_FROMCHARS 0
#               define C4CORE_HAVE_FAST_FLOAT 1
#           endif
#       else
#           if __has_include(<charconv>)
//included above:
//#               include <charconv>
#               if defined(__cpp_lib_to_chars)
#                   define C4CORE_HAVE_STD_TOCHARS 1
#                   define C4CORE_HAVE_STD_FROMCHARS 0 // glibc uses fast_float internally
#                   define C4CORE_HAVE_FAST_FLOAT 1
#               else
#                   define C4CORE_HAVE_STD_TOCHARS 0
#                   define C4CORE_HAVE_STD_FROMCHARS 0
#                   define C4CORE_HAVE_FAST_FLOAT 1
#               endif
#           else
#               define C4CORE_HAVE_STD_TOCHARS 0
#               define C4CORE_HAVE_STD_FROMCHARS 0
#               define C4CORE_HAVE_FAST_FLOAT 1
#           endif
#       endif
#   else
#       define C4CORE_HAVE_STD_TOCHARS 0
#       define C4CORE_HAVE_STD_FROMCHARS 0
#       define C4CORE_HAVE_FAST_FLOAT 1
#   endif
#   if C4CORE_HAVE_FAST_FLOAT
        C4_SUPPRESS_WARNING_GCC_WITH_PUSH("-Wsign-conversion")
        C4_SUPPRESS_WARNING_GCC("-Warray-bounds")
#       if __GNUC__ >= 5
            C4_SUPPRESS_WARNING_GCC("-Wshift-count-overflow")
#       endif
// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/ext/fast_float.hpp
//#       include "c4/ext/fast_float.hpp"
#if !defined(C4_EXT_FAST_FLOAT_HPP_) && !defined(_C4_EXT_FAST_FLOAT_HPP_)
#error "amalgamate: file c4/ext/fast_float.hpp must have been included at this point"
#endif /* C4_EXT_FAST_FLOAT_HPP_ */

        C4_SUPPRESS_WARNING_GCC_POP
#   endif
#elif (C4_CPP >= 17)
#   define C4CORE_HAVE_FAST_FLOAT 0
#   if defined(_MSC_VER)
#       if (C4_MSVC_VERSION >= C4_MSVC_VERSION_2019) // VS2017 and lower do not have these macros
//included above:
//#           include <charconv>
#           define C4CORE_HAVE_STD_TOCHARS 1
#           define C4CORE_HAVE_STD_FROMCHARS 1
#       else
#           define C4CORE_HAVE_STD_TOCHARS 0
#           define C4CORE_HAVE_STD_FROMCHARS 0
#       endif
#   else
#       if __has_include(<charconv>)
//included above:
//#           include <charconv>
#           if defined(__cpp_lib_to_chars)
#               define C4CORE_HAVE_STD_TOCHARS 1
#               define C4CORE_HAVE_STD_FROMCHARS 1 // glibc uses fast_float internally
#           else
#               define C4CORE_HAVE_STD_TOCHARS 0
#               define C4CORE_HAVE_STD_FROMCHARS 0
#           endif
#       else
#           define C4CORE_HAVE_STD_TOCHARS 0
#           define C4CORE_HAVE_STD_FROMCHARS 0
#       endif
#   endif
#else
#   define C4CORE_HAVE_STD_TOCHARS 0
#   define C4CORE_HAVE_STD_FROMCHARS 0
#   define C4CORE_HAVE_FAST_FLOAT 0
#endif


#if !C4CORE_HAVE_STD_FROMCHARS
#include <cstdio>
#endif


#ifdef _MSC_VER
#   pragma warning(push)
#   if C4_MSVC_VERSION != C4_MSVC_VERSION_2017
#       pragma warning(disable: 4800) //'int': forcing value to bool 'true' or 'false' (performance warning)
#   endif
#   pragma warning(disable: 4996) // snprintf/scanf: this function or variable may be unsafe
#elif defined(__clang__)
#   pragma clang diagnostic push
#   pragma clang diagnostic ignored "-Wtautological-constant-out-of-range-compare"
#   pragma clang diagnostic ignored "-Wformat-nonliteral"
#   pragma clang diagnostic ignored "-Wdouble-promotion" // implicit conversion increases floating-point precision
#elif defined(__GNUC__)
#   pragma GCC diagnostic push
#   pragma GCC diagnostic ignored "-Wformat-nonliteral"
#   pragma GCC diagnostic ignored "-Wdouble-promotion" // implicit conversion increases floating-point precision
#   pragma GCC diagnostic ignored "-Wuseless-cast"
#endif


namespace c4 {

#if C4CORE_HAVE_STD_TOCHARS
/** @warning Use only the symbol. Do not rely on the type or naked value of this enum. */
typedef enum : std::underlying_type<std::chars_format>::type {
    /** print the real number in floating point format (like %f) */
    FTOA_FLOAT = static_cast<std::underlying_type<std::chars_format>::type>(std::chars_format::fixed),
    /** print the real number in scientific format (like %e) */
    FTOA_SCIENT = static_cast<std::underlying_type<std::chars_format>::type>(std::chars_format::scientific),
    /** print the real number in flexible format (like %g) */
    FTOA_FLEX = static_cast<std::underlying_type<std::chars_format>::type>(std::chars_format::general),
    /** print the real number in hexadecimal format (like %a) */
    FTOA_HEXA = static_cast<std::underlying_type<std::chars_format>::type>(std::chars_format::hex),
} RealFormat_e;
#else
/** @warning Use only the symbol. Do not rely on the type or naked value of this enum. */
typedef enum : char {
    /** print the real number in floating point format (like %f) */
    FTOA_FLOAT = 'f',
    /** print the real number in scientific format (like %e) */
    FTOA_SCIENT = 'e',
    /** print the real number in flexible format (like %g) */
    FTOA_FLEX = 'g',
    /** print the real number in hexadecimal format (like %a) */
    FTOA_HEXA = 'a',
} RealFormat_e;
#endif


/** in some platforms, int,unsigned int
 *  are not any of int8_t...int64_t and
 *  long,unsigned long are not any of uint8_t...uint64_t */
template<class T>
struct is_fixed_length
{
    enum : bool {
        /** true if T is one of the fixed length signed types */
        value_i = (std::is_integral<T>::value
                   && (std::is_same<T, int8_t>::value
                       || std::is_same<T, int16_t>::value
                       || std::is_same<T, int32_t>::value
                       || std::is_same<T, int64_t>::value)),
        /** true if T is one of the fixed length unsigned types */
        value_u = (std::is_integral<T>::value
                   && (std::is_same<T, uint8_t>::value
                       || std::is_same<T, uint16_t>::value
                       || std::is_same<T, uint32_t>::value
                       || std::is_same<T, uint64_t>::value)),
        /** true if T is one of the fixed length signed or unsigned types */
        value = value_i || value_u
    };
};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

#ifdef _MSC_VER
#   pragma warning(push)
#elif defined(__clang__)
#   pragma clang diagnostic push
#elif defined(__GNUC__)
#   pragma GCC diagnostic push
#   pragma GCC diagnostic ignored "-Wconversion"
#   if __GNUC__ >= 6
#       pragma GCC diagnostic ignored "-Wnull-dereference"
#   endif
#endif

namespace detail {

/* python command to get the values below:
def dec(v):
    return str(v)
for bits in (8, 16, 32, 64):
    imin, imax, umax = (-(1 << (bits - 1))), (1 << (bits - 1)) - 1, (1 << bits) - 1
    for vname, v in (("imin", imin), ("imax", imax), ("umax", umax)):
        for f in (bin, oct, dec, hex):
            print(f"{bits}b: {vname}={v} {f.__name__}: len={len(f(v)):2d}: {v} {f(v)}")
*/

// do not use the type as the template argument because in some
// platforms long!=int32 and long!=int64. Just use the numbytes
// which is more generic and spares lengthy SFINAE code.
template<size_t num_bytes, bool is_signed> struct charconv_digits_;
template<class T> using charconv_digits = charconv_digits_<sizeof(T), std::is_signed<T>::value>;

template<> struct charconv_digits_<1u, true> // int8_t
{
    enum : size_t {
        maxdigits_bin       = 1 + 2 + 8, // -128==-0b10000000
        maxdigits_oct       = 1 + 2 + 3, // -128==-0o200
        maxdigits_dec       = 1     + 3, // -128
        maxdigits_hex       = 1 + 2 + 2, // -128==-0x80
        maxdigits_bin_nopfx =         8, // -128==-0b10000000
        maxdigits_oct_nopfx =         3, // -128==-0o200
        maxdigits_dec_nopfx =         3, // -128
        maxdigits_hex_nopfx =         2, // -128==-0x80
    };
    // min values without sign!
    static constexpr csubstr min_value_dec() noexcept { return csubstr("128"); }
    static constexpr csubstr min_value_hex() noexcept { return csubstr("80"); }
    static constexpr csubstr min_value_oct() noexcept { return csubstr("200"); }
    static constexpr csubstr min_value_bin() noexcept { return csubstr("10000000"); }
    static constexpr csubstr max_value_dec() noexcept { return csubstr("127"); }
    static constexpr bool    is_oct_overflow(csubstr str) noexcept { return !((str.len < 3) || (str.len == 3 && str[0] <= '1')); }
};
template<> struct charconv_digits_<1u, false> // uint8_t
{
    enum : size_t {
        maxdigits_bin       = 2 + 8, // 255 0b11111111
        maxdigits_oct       = 2 + 3, // 255 0o377
        maxdigits_dec       =     3, // 255
        maxdigits_hex       = 2 + 2, // 255 0xff
        maxdigits_bin_nopfx =     8, // 255 0b11111111
        maxdigits_oct_nopfx =     3, // 255 0o377
        maxdigits_dec_nopfx =     3, // 255
        maxdigits_hex_nopfx =     2, // 255 0xff
    };
    static constexpr csubstr max_value_dec() noexcept { return csubstr("255"); }
    static constexpr bool    is_oct_overflow(csubstr str) noexcept { return !((str.len < 3) || (str.len == 3 && str[0] <= '3')); }
};
template<> struct charconv_digits_<2u, true> // int16_t
{
    enum : size_t {
        maxdigits_bin       = 1 + 2 + 16, // -32768 -0b1000000000000000
        maxdigits_oct       = 1 + 2 +  6, // -32768 -0o100000
        maxdigits_dec       = 1     +  5, // -32768 -32768
        maxdigits_hex       = 1 + 2 +  4, // -32768 -0x8000
        maxdigits_bin_nopfx =         16, // -32768 -0b1000000000000000
        maxdigits_oct_nopfx =          6, // -32768 -0o100000
        maxdigits_dec_nopfx =          5, // -32768 -32768
        maxdigits_hex_nopfx =          4, // -32768 -0x8000
    };
    // min values without sign!
    static constexpr csubstr min_value_dec() noexcept { return csubstr("32768"); }
    static constexpr csubstr min_value_hex() noexcept { return csubstr("8000"); }
    static constexpr csubstr min_value_oct() noexcept { return csubstr("100000"); }
    static constexpr csubstr min_value_bin() noexcept { return csubstr("1000000000000000"); }
    static constexpr csubstr max_value_dec() noexcept { return csubstr("32767"); }
    static constexpr bool    is_oct_overflow(csubstr str) noexcept { return !((str.len < 6)); }
};
template<> struct charconv_digits_<2u, false> // uint16_t
{
    enum : size_t {
        maxdigits_bin       = 2 + 16, // 65535 0b1111111111111111
        maxdigits_oct       = 2 +  6, // 65535 0o177777
        maxdigits_dec       =      6, // 65535 65535
        maxdigits_hex       = 2 +  4, // 65535 0xffff
        maxdigits_bin_nopfx =     16, // 65535 0b1111111111111111
        maxdigits_oct_nopfx =      6, // 65535 0o177777
        maxdigits_dec_nopfx =      6, // 65535 65535
        maxdigits_hex_nopfx =      4, // 65535 0xffff
    };
    static constexpr csubstr max_value_dec() noexcept { return csubstr("65535"); }
    static constexpr bool    is_oct_overflow(csubstr str) noexcept { return !((str.len < 6) || (str.len == 6 && str[0] <= '1')); }
};
template<> struct charconv_digits_<4u, true> // int32_t
{
    enum : size_t {
        maxdigits_bin       = 1 + 2 + 32, // len=35: -2147483648 -0b10000000000000000000000000000000
        maxdigits_oct       = 1 + 2 + 11, // len=14: -2147483648 -0o20000000000
        maxdigits_dec       = 1     + 10, // len=11: -2147483648 -2147483648
        maxdigits_hex       = 1 + 2 +  8, // len=11: -2147483648 -0x80000000
        maxdigits_bin_nopfx =         32, // len=35: -2147483648 -0b10000000000000000000000000000000
        maxdigits_oct_nopfx =         11, // len=14: -2147483648 -0o20000000000
        maxdigits_dec_nopfx =         10, // len=11: -2147483648 -2147483648
        maxdigits_hex_nopfx =          8, // len=11: -2147483648 -0x80000000
    };
    // min values without sign!
    static constexpr csubstr min_value_dec() noexcept { return csubstr("2147483648"); }
    static constexpr csubstr min_value_hex() noexcept { return csubstr("80000000"); }
    static constexpr csubstr min_value_oct() noexcept { return csubstr("20000000000"); }
    static constexpr csubstr min_value_bin() noexcept { return csubstr("10000000000000000000000000000000"); }
    static constexpr csubstr max_value_dec() noexcept { return csubstr("2147483647"); }
    static constexpr bool    is_oct_overflow(csubstr str) noexcept { return !((str.len < 11) || (str.len == 11 && str[0] <= '1')); }
};
template<> struct charconv_digits_<4u, false> // uint32_t
{
    enum : size_t {
        maxdigits_bin       = 2 + 32, // len=34: 4294967295 0b11111111111111111111111111111111
        maxdigits_oct       = 2 + 11, // len=13: 4294967295 0o37777777777
        maxdigits_dec       =     10, // len=10: 4294967295 4294967295
        maxdigits_hex       = 2 +  8, // len=10: 4294967295 0xffffffff
        maxdigits_bin_nopfx =     32, // len=34: 4294967295 0b11111111111111111111111111111111
        maxdigits_oct_nopfx =     11, // len=13: 4294967295 0o37777777777
        maxdigits_dec_nopfx =     10, // len=10: 4294967295 4294967295
        maxdigits_hex_nopfx =      8, // len=10: 4294967295 0xffffffff
    };
    static constexpr csubstr max_value_dec() noexcept { return csubstr("4294967295"); }
    static constexpr bool is_oct_overflow(csubstr str) noexcept { return !((str.len < 11) || (str.len == 11 && str[0] <= '3')); }
};
template<> struct charconv_digits_<8u, true> // int32_t
{
    enum : size_t {
        maxdigits_bin       = 1 + 2 + 64, // len=67: -9223372036854775808 -0b1000000000000000000000000000000000000000000000000000000000000000
        maxdigits_oct       = 1 + 2 + 22, // len=25: -9223372036854775808 -0o1000000000000000000000
        maxdigits_dec       = 1     + 19, // len=20: -9223372036854775808 -9223372036854775808
        maxdigits_hex       = 1 + 2 + 16, // len=19: -9223372036854775808 -0x8000000000000000
        maxdigits_bin_nopfx =         64, // len=67: -9223372036854775808 -0b1000000000000000000000000000000000000000000000000000000000000000
        maxdigits_oct_nopfx =         22, // len=25: -9223372036854775808 -0o1000000000000000000000
        maxdigits_dec_nopfx =         19, // len=20: -9223372036854775808 -9223372036854775808
        maxdigits_hex_nopfx =         16, // len=19: -9223372036854775808 -0x8000000000000000
    };
    static constexpr csubstr min_value_dec() noexcept { return csubstr("9223372036854775808"); }
    static constexpr csubstr min_value_hex() noexcept { return csubstr("8000000000000000"); }
    static constexpr csubstr min_value_oct() noexcept { return csubstr("1000000000000000000000"); }
    static constexpr csubstr min_value_bin() noexcept { return csubstr("1000000000000000000000000000000000000000000000000000000000000000"); }
    static constexpr csubstr max_value_dec() noexcept { return csubstr("9223372036854775807"); }
    static constexpr bool    is_oct_overflow(csubstr str) noexcept { return !((str.len < 22)); }
};
template<> struct charconv_digits_<8u, false>
{
    enum : size_t {
        maxdigits_bin       = 2 + 64, // len=66: 18446744073709551615 0b1111111111111111111111111111111111111111111111111111111111111111
        maxdigits_oct       = 2 + 22, // len=24: 18446744073709551615 0o1777777777777777777777
        maxdigits_dec       =     20, // len=20: 18446744073709551615 18446744073709551615
        maxdigits_hex       = 2 + 16, // len=18: 18446744073709551615 0xffffffffffffffff
        maxdigits_bin_nopfx =     64, // len=66: 18446744073709551615 0b1111111111111111111111111111111111111111111111111111111111111111
        maxdigits_oct_nopfx =     22, // len=24: 18446744073709551615 0o1777777777777777777777
        maxdigits_dec_nopfx =     20, // len=20: 18446744073709551615 18446744073709551615
        maxdigits_hex_nopfx =     16, // len=18: 18446744073709551615 0xffffffffffffffff
    };
    static constexpr csubstr max_value_dec() noexcept { return csubstr("18446744073709551615"); }
    static constexpr bool    is_oct_overflow(csubstr str) noexcept { return !((str.len < 22) || (str.len == 22 && str[0] <= '1')); }
};
} // namespace detail


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

// Helper macros, undefined below
#define _c4append(c) { if(C4_LIKELY(pos < buf.len)) { buf.str[pos++] = static_cast<char>(c); } else { ++pos; } }
#define _c4appendhex(i) { if(C4_LIKELY(pos < buf.len)) { buf.str[pos++] = hexchars[i]; } else { ++pos; } }

/** @name digits_dec return the number of digits required to encode a
 * decimal number.
 *
 * @note At first sight this code may look heavily branchy and
 * therefore inefficient. However, measurements revealed this to be
 * the fastest among the alternatives.
 *
 * @see https://github.com/biojppm/c4core/pull/77 */
/** @{ */

template<class T>
C4_CONSTEXPR14 C4_ALWAYS_INLINE
auto digits_dec(T v) noexcept
    -> typename std::enable_if<sizeof(T) == 1u, unsigned>::type
{
    C4_STATIC_ASSERT(std::is_integral<T>::value);
    C4_ASSERT(v >= 0);
    return ((v >= 100) ? 3u : ((v >= 10) ? 2u : 1u));
}

template<class T>
C4_CONSTEXPR14 C4_ALWAYS_INLINE
auto digits_dec(T v) noexcept
    -> typename std::enable_if<sizeof(T) == 2u, unsigned>::type
{
    C4_STATIC_ASSERT(std::is_integral<T>::value);
    C4_ASSERT(v >= 0);
    return ((v >= 10000) ? 5u : (v >= 1000) ? 4u : (v >= 100) ? 3u : (v >= 10) ? 2u : 1u);
}

template<class T>
C4_CONSTEXPR14 C4_ALWAYS_INLINE
auto digits_dec(T v) noexcept
    -> typename std::enable_if<sizeof(T) == 4u, unsigned>::type
{
    C4_STATIC_ASSERT(std::is_integral<T>::value);
    C4_ASSERT(v >= 0);
    return ((v >= 1000000000) ? 10u : (v >= 100000000) ? 9u : (v >= 10000000) ? 8u :
            (v >= 1000000) ? 7u : (v >= 100000) ? 6u : (v >= 10000) ? 5u :
            (v >= 1000) ? 4u : (v >= 100) ? 3u : (v >= 10) ? 2u : 1u);
}

template<class T>
C4_CONSTEXPR14 C4_ALWAYS_INLINE
auto digits_dec(T v) noexcept
    -> typename std::enable_if<sizeof(T) == 8u, unsigned>::type
{
    // thanks @fargies!!!
    // https://github.com/biojppm/c4core/pull/77#issuecomment-1063753568
    C4_STATIC_ASSERT(std::is_integral<T>::value);
    C4_ASSERT(v >= 0);
    if(v >= 1000000000) // 10
    {
        if(v >= 100000000000000) // 15 [15-20] range
        {
            if(v >= 100000000000000000) // 18 (15 + (20 - 15) / 2)
            {
                if((typename std::make_unsigned<T>::type)v >= 10000000000000000000u) // 20
                    return 20u;
                else
                    return (v >= 1000000000000000000) ? 19u : 18u;
            }
            else if(v >= 10000000000000000) // 17
                return 17u;
            else
                return(v >= 1000000000000000) ? 16u : 15u;
        }
        else if(v >= 1000000000000) // 13
            return (v >= 10000000000000) ? 14u : 13u;
        else if(v >= 100000000000) // 12
            return 12;
        else
            return(v >= 10000000000) ? 11u : 10u;
    }
    else if(v >= 10000) // 5 [5-9] range
    {
        if(v >= 10000000) // 8
            return (v >= 100000000) ? 9u : 8u;
        else if(v >= 1000000) // 7
            return 7;
        else
            return (v >= 100000) ? 6u : 5u;
    }
    else if(v >= 100)
        return (v >= 1000) ? 4u : 3u;
    else
        return (v >= 10) ? 2u : 1u;
}

/** @} */


template<class T>
C4_CONSTEXPR14 C4_ALWAYS_INLINE unsigned digits_hex(T v) noexcept
{
    C4_STATIC_ASSERT(std::is_integral<T>::value);
    C4_ASSERT(v >= 0);
    return v ? 1u + (msb((typename std::make_unsigned<T>::type)v) >> 2u) : 1u;
}

template<class T>
C4_CONSTEXPR14 C4_ALWAYS_INLINE unsigned digits_bin(T v) noexcept
{
    C4_STATIC_ASSERT(std::is_integral<T>::value);
    C4_ASSERT(v >= 0);
    return v ? 1u + msb((typename std::make_unsigned<T>::type)v) : 1u;
}

template<class T>
C4_CONSTEXPR14 C4_ALWAYS_INLINE unsigned digits_oct(T v_) noexcept
{
    // TODO: is there a better way?
    C4_STATIC_ASSERT(std::is_integral<T>::value);
    C4_ASSERT(v_ >= 0);
    using U = typename
        std::conditional<sizeof(T) <= sizeof(unsigned),
                         unsigned,
                         typename std::make_unsigned<T>::type>::type;
    U v = (U) v_;  // safe because we require v_ >= 0
    unsigned __n = 1;
    const unsigned __b2 = 64u;
    const unsigned __b3 = __b2 * 8u;
    const unsigned long __b4 = __b3 * 8u;
    while(true)
	{
        if(v < 8u)
            return __n;
        if(v < __b2)
            return __n + 1;
        if(v < __b3)
            return __n + 2;
        if(v < __b4)
            return __n + 3;
        v /= (U) __b4;
        __n += 4;
	}
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

namespace detail {
C4_INLINE_CONSTEXPR const char hexchars[] = "0123456789abcdef";
C4_INLINE_CONSTEXPR const char digits0099[] =
    "0001020304050607080910111213141516171819"
    "2021222324252627282930313233343536373839"
    "4041424344454647484950515253545556575859"
    "6061626364656667686970717273747576777879"
    "8081828384858687888990919293949596979899";
} // namespace detail

C4_SUPPRESS_WARNING_GCC_PUSH
C4_SUPPRESS_WARNING_GCC("-Warray-bounds")  // gcc has false positives here
#if (defined(__GNUC__) && (__GNUC__ >= 7))
C4_SUPPRESS_WARNING_GCC("-Wstringop-overflow")  // gcc has false positives here
#endif

template<class T>
C4_HOT C4_ALWAYS_INLINE
void write_dec_unchecked(substr buf, T v, unsigned digits_v) noexcept
{
    C4_STATIC_ASSERT(std::is_integral<T>::value);
    C4_ASSERT(v >= 0);
    C4_ASSERT(buf.len >= digits_v);
    C4_XASSERT(digits_v == digits_dec(v));
    // in bm_xtoa: checkoncelog_singlediv_write2
    while(v >= T(100))
    {
        const T quo = v / T(100);
        const auto num = (v - quo * T(100)) << 1u;
        v = quo;
        buf.str[--digits_v] = detail::digits0099[num + 1];
        buf.str[--digits_v] = detail::digits0099[num];
    }
    if(v >= T(10))
    {
        C4_ASSERT(digits_v == 2);
        const auto num = v << 1u;
        buf.str[1] = detail::digits0099[num + 1];
        buf.str[0] = detail::digits0099[num];
    }
    else
    {
        C4_ASSERT(digits_v == 1);
        buf.str[0] = (char)('0' + v);
    }
}


template<class T>
C4_HOT C4_ALWAYS_INLINE
void write_hex_unchecked(substr buf, T v, unsigned digits_v) noexcept
{
    C4_STATIC_ASSERT(std::is_integral<T>::value);
    C4_ASSERT(v >= 0);
    C4_ASSERT(buf.len >= digits_v);
    C4_XASSERT(digits_v == digits_hex(v));
    do {
        buf.str[--digits_v] = detail::hexchars[v & T(15)];
        v >>= 4;
    } while(v);
    C4_ASSERT(digits_v == 0);
}


template<class T>
C4_HOT C4_ALWAYS_INLINE
void write_oct_unchecked(substr buf, T v, unsigned digits_v) noexcept
{
    C4_STATIC_ASSERT(std::is_integral<T>::value);
    C4_ASSERT(v >= 0);
    C4_ASSERT(buf.len >= digits_v);
    C4_XASSERT(digits_v == digits_oct(v));
    do {
        buf.str[--digits_v] = (char)('0' + (v & T(7)));
        v >>= 3;
    } while(v);
    C4_ASSERT(digits_v == 0);
}


template<class T>
C4_HOT C4_ALWAYS_INLINE
void write_bin_unchecked(substr buf, T v, unsigned digits_v) noexcept
{
    C4_STATIC_ASSERT(std::is_integral<T>::value);
    C4_ASSERT(v >= 0);
    C4_ASSERT(buf.len >= digits_v);
    C4_XASSERT(digits_v == digits_bin(v));
    do {
        buf.str[--digits_v] = (char)('0' + (v & T(1)));
        v >>= 1;
    } while(v);
    C4_ASSERT(digits_v == 0);
}


/** write an integer to a string in decimal format. This is the
 * lowest level (and the fastest) function to do this task.
 * @note does not accept negative numbers
 * @note the resulting string is NOT zero-terminated.
 * @note it is ok to call this with an empty or too-small buffer;
 * no writes will occur, and the required size will be returned
 * @return the number of characters required for the buffer. */
template<class T>
C4_ALWAYS_INLINE size_t write_dec(substr buf, T v) noexcept
{
    C4_STATIC_ASSERT(std::is_integral<T>::value);
    C4_ASSERT(v >= 0);
    unsigned digits = digits_dec(v);
    if(C4_LIKELY(buf.len >= digits))
        write_dec_unchecked(buf, v, digits);
    return digits;
}

/** write an integer to a string in hexadecimal format. This is the
 * lowest level (and the fastest) function to do this task.
 * @note does not accept negative numbers
 * @note does not prefix with 0x
 * @note the resulting string is NOT zero-terminated.
 * @note it is ok to call this with an empty or too-small buffer;
 * no writes will occur, and the required size will be returned
 * @return the number of characters required for the buffer. */
template<class T>
C4_ALWAYS_INLINE size_t write_hex(substr buf, T v) noexcept
{
    C4_STATIC_ASSERT(std::is_integral<T>::value);
    C4_ASSERT(v >= 0);
    unsigned digits = digits_hex(v);
    if(C4_LIKELY(buf.len >= digits))
        write_hex_unchecked(buf, v, digits);
    return digits;
}

/** write an integer to a string in octal format. This is the
 * lowest level (and the fastest) function to do this task.
 * @note does not accept negative numbers
 * @note does not prefix with 0o
 * @note the resulting string is NOT zero-terminated.
 * @note it is ok to call this with an empty or too-small buffer;
 * no writes will occur, and the required size will be returned
 * @return the number of characters required for the buffer. */
template<class T>
C4_ALWAYS_INLINE size_t write_oct(substr buf, T v) noexcept
{
    C4_STATIC_ASSERT(std::is_integral<T>::value);
    C4_ASSERT(v >= 0);
    unsigned digits = digits_oct(v);
    if(C4_LIKELY(buf.len >= digits))
        write_oct_unchecked(buf, v, digits);
    return digits;
}

/** write an integer to a string in binary format. This is the
 * lowest level (and the fastest) function to do this task.
 * @note does not accept negative numbers
 * @note does not prefix with 0b
 * @note the resulting string is NOT zero-terminated.
 * @note it is ok to call this with an empty or too-small buffer;
 * no writes will occur, and the required size will be returned
 * @return the number of characters required for the buffer. */
template<class T>
C4_ALWAYS_INLINE size_t write_bin(substr buf, T v) noexcept
{
    C4_STATIC_ASSERT(std::is_integral<T>::value);
    C4_ASSERT(v >= 0);
    unsigned digits = digits_bin(v);
    C4_ASSERT(digits > 0);
    if(C4_LIKELY(buf.len >= digits))
        write_bin_unchecked(buf, v, digits);
    return digits;
}


namespace detail {
template<class U> using NumberWriter = size_t (*)(substr, U);
template<class T, NumberWriter<T> writer>
size_t write_num_digits(substr buf, T v, size_t num_digits) noexcept
{
    C4_STATIC_ASSERT(std::is_integral<T>::value);
    size_t ret = writer(buf, v);
    if(ret >= num_digits)
        return ret;
    else if(ret >= buf.len || num_digits > buf.len)
        return num_digits;
    C4_ASSERT(num_digits >= ret);
    size_t delta = static_cast<size_t>(num_digits - ret);
    memmove(buf.str + delta, buf.str, ret);
    memset(buf.str, '0', delta);
    return num_digits;
}
} // namespace detail


/** same as c4::write_dec(), but pad with zeroes on the left
 * such that the resulting string is @p num_digits wide.
 * If the given number is requires more than num_digits, then the number prevails. */
template<class T>
C4_ALWAYS_INLINE size_t write_dec(substr buf, T val, size_t num_digits) noexcept
{
    return detail::write_num_digits<T, &write_dec<T>>(buf, val, num_digits);
}

/** same as c4::write_hex(), but pad with zeroes on the left
 * such that the resulting string is @p num_digits wide.
 * If the given number is requires more than num_digits, then the number prevails. */
template<class T>
C4_ALWAYS_INLINE size_t write_hex(substr buf, T val, size_t num_digits) noexcept
{
    return detail::write_num_digits<T, &write_hex<T>>(buf, val, num_digits);
}

/** same as c4::write_bin(), but pad with zeroes on the left
 * such that the resulting string is @p num_digits wide.
 * If the given number is requires more than num_digits, then the number prevails. */
template<class T>
C4_ALWAYS_INLINE size_t write_bin(substr buf, T val, size_t num_digits) noexcept
{
    return detail::write_num_digits<T, &write_bin<T>>(buf, val, num_digits);
}

/** same as c4::write_oct(), but pad with zeroes on the left
 * such that the resulting string is @p num_digits wide.
 * If the given number is requires more than num_digits, then the number prevails. */
template<class T>
C4_ALWAYS_INLINE size_t write_oct(substr buf, T val, size_t num_digits) noexcept
{
    return detail::write_num_digits<T, &write_oct<T>>(buf, val, num_digits);
}

C4_SUPPRESS_WARNING_GCC_POP


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** read a decimal integer from a string. This is the
 * lowest level (and the fastest) function to do this task.
 * @note does not accept negative numbers
 * @note The string must be trimmed. Whitespace is not accepted.
 * @note the string must not be empty
 * @note there is no check for overflow; the value wraps around
 * in a way similar to the standard C/C++ overflow behavior.
 * For example, `read_dec<int8_t>("128", &val)` returns true
 * and val will be set to 0 because 127 is the max i8 value.
 * @see overflows<T>() to find out if a number string overflows a type range
 * @return true if the conversion was successful (no overflow check) */
template<class I>
C4_ALWAYS_INLINE bool read_dec(csubstr s, I *C4_RESTRICT v) noexcept
{
    C4_STATIC_ASSERT(std::is_integral<I>::value);
    C4_ASSERT(!s.empty());
    *v = 0;
    for(char c : s)
    {
        if(C4_UNLIKELY(c < '0' || c > '9'))
            return false;
        *v = (*v) * I(10) + (I(c) - I('0'));
    }
    return true;
}

/** read an hexadecimal integer from a string. This is the
 * lowest level (and the fastest) function to do this task.
 * @note does not accept negative numbers
 * @note does not accept leading 0x or 0X
 * @note the string must not be empty
 * @note the string must be trimmed. Whitespace is not accepted.
 * @note there is no check for overflow; the value wraps around
 * in a way similar to the standard C/C++ overflow behavior.
 * For example, `read_hex<int8_t>("80", &val)` returns true
 * and val will be set to 0 because 7f is the max i8 value.
 * @see overflows<T>() to find out if a number string overflows a type range
 * @return true if the conversion was successful (no overflow check) */
template<class I>
C4_ALWAYS_INLINE bool read_hex(csubstr s, I *C4_RESTRICT v) noexcept
{
    C4_STATIC_ASSERT(std::is_integral<I>::value);
    C4_ASSERT(!s.empty());
    *v = 0;
    for(char c : s)
    {
        I cv;
        if(c >= '0' && c <= '9')
            cv = I(c) - I('0');
        else if(c >= 'a' && c <= 'f')
            cv = I(10) + (I(c) - I('a'));
        else if(c >= 'A' && c <= 'F')
            cv = I(10) + (I(c) - I('A'));
        else
            return false;
        *v = (*v) * I(16) + cv;
    }
    return true;
}

/** read a binary integer from a string. This is the
 * lowest level (and the fastest) function to do this task.
 * @note does not accept negative numbers
 * @note does not accept leading 0b or 0B
 * @note the string must not be empty
 * @note the string must be trimmed. Whitespace is not accepted.
 * @note there is no check for overflow; the value wraps around
 * in a way similar to the standard C/C++ overflow behavior.
 * For example, `read_bin<int8_t>("10000000", &val)` returns true
 * and val will be set to 0 because 1111111 is the max i8 value.
 * @see overflows<T>() to find out if a number string overflows a type range
 * @return true if the conversion was successful (no overflow check) */
template<class I>
C4_ALWAYS_INLINE bool read_bin(csubstr s, I *C4_RESTRICT v) noexcept
{
    C4_STATIC_ASSERT(std::is_integral<I>::value);
    C4_ASSERT(!s.empty());
    *v = 0;
    for(char c : s)
    {
        *v <<= 1;
        if(c == '1')
            *v |= 1;
        else if(c != '0')
            return false;
    }
    return true;
}

/** read an octal integer from a string. This is the
 * lowest level (and the fastest) function to do this task.
 * @note does not accept negative numbers
 * @note does not accept leading 0o or 0O
 * @note the string must not be empty
 * @note the string must be trimmed. Whitespace is not accepted.
 * @note there is no check for overflow; the value wraps around
 * in a way similar to the standard C/C++ overflow behavior.
 * For example, `read_oct<int8_t>("200", &val)` returns true
 * and val will be set to 0 because 177 is the max i8 value.
 * @see overflows<T>() to find out if a number string overflows a type range
 * @return true if the conversion was successful (no overflow check) */
template<class I>
C4_ALWAYS_INLINE bool read_oct(csubstr s, I *C4_RESTRICT v) noexcept
{
    C4_STATIC_ASSERT(std::is_integral<I>::value);
    C4_ASSERT(!s.empty());
    *v = 0;
    for(char c : s)
    {
        if(C4_UNLIKELY(c < '0' || c > '7'))
            return false;
        *v = (*v) * I(8) + (I(c) - I('0'));
    }
    return true;
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

namespace detail {
inline size_t _itoa2buf(substr buf, size_t pos, csubstr val) noexcept
{
    C4_ASSERT(pos + val.len <= buf.len);
    memcpy(buf.str + pos, val.str, val.len);
    return pos + val.len;
}
inline size_t _itoa2bufwithdigits(substr buf, size_t pos, size_t num_digits, csubstr val) noexcept
{
    num_digits = num_digits > val.len ? num_digits - val.len : 0;
    C4_ASSERT(num_digits + val.len <= buf.len);
    for(size_t i = 0; i < num_digits; ++i)
        _c4append('0');
    return detail::_itoa2buf(buf, pos, val);
}
template<class I>
C4_NO_INLINE size_t _itoadec2buf(substr buf) noexcept
{
    using digits_type = detail::charconv_digits<I>;
    if(C4_UNLIKELY(buf.len < digits_type::maxdigits_dec))
        return digits_type::maxdigits_dec;
    buf.str[0] = '-';
    return detail::_itoa2buf(buf, 1, digits_type::min_value_dec());
}
template<class I>
C4_NO_INLINE size_t _itoa2buf(substr buf, I radix) noexcept
{
    using digits_type = detail::charconv_digits<I>;
    size_t pos = 0;
    if(C4_LIKELY(buf.len > 0))
        buf.str[pos++] = '-';
    switch(radix)
    {
    case I(10):
        if(C4_UNLIKELY(buf.len < digits_type::maxdigits_dec))
            return digits_type::maxdigits_dec;
        pos =_itoa2buf(buf, pos, digits_type::min_value_dec());
        break;
    case I(16):
        if(C4_UNLIKELY(buf.len < digits_type::maxdigits_hex))
            return digits_type::maxdigits_hex;
        buf.str[pos++] = '0';
        buf.str[pos++] = 'x';
        pos = _itoa2buf(buf, pos, digits_type::min_value_hex());
        break;
    case I( 2):
        if(C4_UNLIKELY(buf.len < digits_type::maxdigits_bin))
            return digits_type::maxdigits_bin;
        buf.str[pos++] = '0';
        buf.str[pos++] = 'b';
        pos = _itoa2buf(buf, pos, digits_type::min_value_bin());
        break;
    case I( 8):
        if(C4_UNLIKELY(buf.len < digits_type::maxdigits_oct))
            return digits_type::maxdigits_oct;
        buf.str[pos++] = '0';
        buf.str[pos++] = 'o';
        pos = _itoa2buf(buf, pos, digits_type::min_value_oct());
        break;
    }
    return pos;
}
template<class I>
C4_NO_INLINE size_t _itoa2buf(substr buf, I radix, size_t num_digits) noexcept
{
    using digits_type = detail::charconv_digits<I>;
    size_t pos = 0;
    size_t needed_digits = 0;
    if(C4_LIKELY(buf.len > 0))
        buf.str[pos++] = '-';
    switch(radix)
    {
    case I(10):
        // add 1 to account for -
        needed_digits = num_digits+1 > digits_type::maxdigits_dec ? num_digits+1 : digits_type::maxdigits_dec;
        if(C4_UNLIKELY(buf.len < needed_digits))
            return needed_digits;
        pos = _itoa2bufwithdigits(buf, pos, num_digits, digits_type::min_value_dec());
        break;
    case I(16):
        // add 3 to account for -0x
        needed_digits = num_digits+3 > digits_type::maxdigits_hex ? num_digits+3 : digits_type::maxdigits_hex;
        if(C4_UNLIKELY(buf.len < needed_digits))
            return needed_digits;
        buf.str[pos++] = '0';
        buf.str[pos++] = 'x';
        pos = _itoa2bufwithdigits(buf, pos, num_digits, digits_type::min_value_hex());
        break;
    case I( 2):
        // add 3 to account for -0b
        needed_digits = num_digits+3 > digits_type::maxdigits_bin ? num_digits+3 : digits_type::maxdigits_bin;
        if(C4_UNLIKELY(buf.len < needed_digits))
            return needed_digits;
        C4_ASSERT(buf.len >= digits_type::maxdigits_bin);
        buf.str[pos++] = '0';
        buf.str[pos++] = 'b';
        pos = _itoa2bufwithdigits(buf, pos, num_digits, digits_type::min_value_bin());
        break;
    case I( 8):
        // add 3 to account for -0o
        needed_digits = num_digits+3 > digits_type::maxdigits_oct ? num_digits+3 : digits_type::maxdigits_oct;
        if(C4_UNLIKELY(buf.len < needed_digits))
            return needed_digits;
        C4_ASSERT(buf.len >= digits_type::maxdigits_oct);
        buf.str[pos++] = '0';
        buf.str[pos++] = 'o';
        pos = _itoa2bufwithdigits(buf, pos, num_digits, digits_type::min_value_oct());
        break;
    }
    return pos;
}
} // namespace detail


/** convert an integral signed decimal to a string.
 * @note the resulting string is NOT zero-terminated.
 * @note it is ok to call this with an empty or too-small buffer;
 * no writes will occur, and the needed size will be returned
 * @return the number of characters required for the buffer. */
template<class T>
C4_ALWAYS_INLINE size_t itoa(substr buf, T v) noexcept
{
    C4_STATIC_ASSERT(std::is_signed<T>::value);
    if(v >= T(0))
    {
        // write_dec() checks the buffer size, so no need to check here
        return write_dec(buf, v);
    }
    // when T is the min value (eg i8: -128), negating it
    // will overflow, so treat the min as a special case
    else if(C4_LIKELY(v != std::numeric_limits<T>::min()))
    {
        v = -v;
        unsigned digits = digits_dec(v);
        if(C4_LIKELY(buf.len >= digits + 1u))
        {
            buf.str[0] = '-';
            write_dec_unchecked(buf.sub(1), v, digits);
        }
        return digits + 1u;
    }
    return detail::_itoadec2buf<T>(buf);
}

/** convert an integral signed integer to a string, using a specific
 * radix. The radix must be 2, 8, 10 or 16.
 *
 * @note the resulting string is NOT zero-terminated.
 * @note it is ok to call this with an empty or too-small buffer;
 * no writes will occur, and the needed size will be returned
 * @return the number of characters required for the buffer. */
template<class T>
C4_ALWAYS_INLINE size_t itoa(substr buf, T v, T radix) noexcept
{
    C4_STATIC_ASSERT(std::is_signed<T>::value);
    C4_ASSERT(radix == 2 || radix == 8 || radix == 10 || radix == 16);
    C4_SUPPRESS_WARNING_GCC_PUSH
    #if (defined(__GNUC__) && (__GNUC__ >= 7))
        C4_SUPPRESS_WARNING_GCC("-Wstringop-overflow")  // gcc has a false positive here
    #endif
    // when T is the min value (eg i8: -128), negating it
    // will overflow, so treat the min as a special case
    if(C4_LIKELY(v != std::numeric_limits<T>::min()))
    {
        unsigned pos = 0;
        if(v < 0)
        {
            v = -v;
            if(C4_LIKELY(buf.len > 0))
                buf.str[pos] = '-';
            ++pos;
        }
        unsigned digits = 0;
        switch(radix)
        {
        case T(10):
            digits = digits_dec(v);
            if(C4_LIKELY(buf.len >= pos + digits))
                write_dec_unchecked(buf.sub(pos), v, digits);
            break;
        case T(16):
            digits = digits_hex(v);
            if(C4_LIKELY(buf.len >= pos + 2u + digits))
            {
                buf.str[pos + 0] = '0';
                buf.str[pos + 1] = 'x';
                write_hex_unchecked(buf.sub(pos + 2), v, digits);
            }
            digits += 2u;
            break;
        case T(2):
            digits = digits_bin(v);
            if(C4_LIKELY(buf.len >= pos + 2u + digits))
            {
                buf.str[pos + 0] = '0';
                buf.str[pos + 1] = 'b';
                write_bin_unchecked(buf.sub(pos + 2), v, digits);
            }
            digits += 2u;
            break;
        case T(8):
            digits = digits_oct(v);
            if(C4_LIKELY(buf.len >= pos + 2u + digits))
            {
                buf.str[pos + 0] = '0';
                buf.str[pos + 1] = 'o';
                write_oct_unchecked(buf.sub(pos + 2), v, digits);
            }
            digits += 2u;
            break;
        }
        return pos + digits;
    }
    C4_SUPPRESS_WARNING_GCC_POP
    // when T is the min value (eg i8: -128), negating it
    // will overflow
    return detail::_itoa2buf<T>(buf, radix);
}


/** same as c4::itoa(), but pad with zeroes on the left such that the
 * resulting string is @p num_digits wide, not accounting for radix
 * prefix (0x,0o,0b). The @p radix must be 2, 8, 10 or 16.
 *
 * @note the resulting string is NOT zero-terminated.
 * @note it is ok to call this with an empty or too-small buffer;
 * no writes will occur, and the needed size will be returned
 * @return the number of characters required for the buffer. */
template<class T>
C4_ALWAYS_INLINE size_t itoa(substr buf, T v, T radix, size_t num_digits) noexcept
{
    C4_STATIC_ASSERT(std::is_signed<T>::value);
    C4_ASSERT(radix == 2 || radix == 8 || radix == 10 || radix == 16);
    C4_SUPPRESS_WARNING_GCC_PUSH
    #if (defined(__GNUC__) && (__GNUC__ >= 7))
        C4_SUPPRESS_WARNING_GCC("-Wstringop-overflow")  // gcc has a false positive here
    #endif
    // when T is the min value (eg i8: -128), negating it
    // will overflow, so treat the min as a special case
    if(C4_LIKELY(v != std::numeric_limits<T>::min()))
    {
        unsigned pos = 0;
        if(v < 0)
        {
            v = -v;
            if(C4_LIKELY(buf.len > 0))
                buf.str[pos] = '-';
            ++pos;
        }
        unsigned total_digits = 0;
        switch(radix)
        {
        case T(10):
            total_digits = digits_dec(v);
            total_digits = pos + (unsigned)(num_digits > total_digits ? num_digits : total_digits);
            if(C4_LIKELY(buf.len >= total_digits))
                write_dec(buf.sub(pos), v, num_digits);
            break;
        case T(16):
            total_digits = digits_hex(v);
            total_digits = pos + 2u + (unsigned)(num_digits > total_digits ? num_digits : total_digits);
            if(C4_LIKELY(buf.len >= total_digits))
            {
                buf.str[pos + 0] = '0';
                buf.str[pos + 1] = 'x';
                write_hex(buf.sub(pos + 2), v, num_digits);
            }
            break;
        case T(2):
            total_digits = digits_bin(v);
            total_digits = pos + 2u + (unsigned)(num_digits > total_digits ? num_digits : total_digits);
            if(C4_LIKELY(buf.len >= total_digits))
            {
                buf.str[pos + 0] = '0';
                buf.str[pos + 1] = 'b';
                write_bin(buf.sub(pos + 2), v, num_digits);
            }
            break;
        case T(8):
            total_digits = digits_oct(v);
            total_digits = pos + 2u + (unsigned)(num_digits > total_digits ? num_digits : total_digits);
            if(C4_LIKELY(buf.len >= total_digits))
            {
                buf.str[pos + 0] = '0';
                buf.str[pos + 1] = 'o';
                write_oct(buf.sub(pos + 2), v, num_digits);
            }
            break;
        }
        return total_digits;
    }
    C4_SUPPRESS_WARNING_GCC_POP
    // when T is the min value (eg i8: -128), negating it
    // will overflow
    return detail::_itoa2buf<T>(buf, radix, num_digits);
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** convert an integral unsigned decimal to a string.
 *
 * @note the resulting string is NOT zero-terminated.
 * @note it is ok to call this with an empty or too-small buffer;
 * no writes will occur, and the needed size will be returned
 * @return the number of characters required for the buffer. */
template<class T>
C4_ALWAYS_INLINE size_t utoa(substr buf, T v) noexcept
{
    C4_STATIC_ASSERT(std::is_unsigned<T>::value);
    // write_dec() does the buffer length check, so no need to check here
    return write_dec(buf, v);
}

/** convert an integral unsigned integer to a string, using a specific
 * radix. The radix must be 2, 8, 10 or 16.
 *
 * @note the resulting string is NOT zero-terminated.
 * @note it is ok to call this with an empty or too-small buffer;
 * no writes will occur, and the needed size will be returned
 * @return the number of characters required for the buffer. */
template<class T>
C4_ALWAYS_INLINE size_t utoa(substr buf, T v, T radix) noexcept
{
    C4_STATIC_ASSERT(std::is_unsigned<T>::value);
    C4_ASSERT(radix == 10 || radix == 16 || radix == 2 || radix == 8);
    unsigned digits = 0;
    switch(radix)
    {
    case T(10):
        digits = digits_dec(v);
        if(C4_LIKELY(buf.len >= digits))
            write_dec_unchecked(buf, v, digits);
        break;
    case T(16):
        digits = digits_hex(v);
        if(C4_LIKELY(buf.len >= digits+2u))
        {
            buf.str[0] = '0';
            buf.str[1] = 'x';
            write_hex_unchecked(buf.sub(2), v, digits);
        }
        digits += 2u;
        break;
    case T(2):
        digits = digits_bin(v);
        if(C4_LIKELY(buf.len >= digits+2u))
        {
            buf.str[0] = '0';
            buf.str[1] = 'b';
            write_bin_unchecked(buf.sub(2), v, digits);
        }
        digits += 2u;
        break;
    case T(8):
        digits = digits_oct(v);
        if(C4_LIKELY(buf.len >= digits+2u))
        {
            buf.str[0] = '0';
            buf.str[1] = 'o';
            write_oct_unchecked(buf.sub(2), v, digits);
        }
        digits += 2u;
        break;
    }
    return digits;
}

/** same as c4::utoa(), but pad with zeroes on the left such that the
 * resulting string is @p num_digits wide. The @p radix must be 2,
 * 8, 10 or 16.
 *
 * @note the resulting string is NOT zero-terminated.
 * @note it is ok to call this with an empty or too-small buffer;
 * no writes will occur, and the needed size will be returned
 * @return the number of characters required for the buffer. */
template<class T>
C4_ALWAYS_INLINE size_t utoa(substr buf, T v, T radix, size_t num_digits) noexcept
{
    C4_STATIC_ASSERT(std::is_unsigned<T>::value);
    C4_ASSERT(radix == 10 || radix == 16 || radix == 2 || radix == 8);
    unsigned total_digits = 0;
    switch(radix)
    {
    case T(10):
        total_digits = digits_dec(v);
        total_digits = (unsigned)(num_digits > total_digits ? num_digits : total_digits);
        if(C4_LIKELY(buf.len >= total_digits))
            write_dec(buf, v, num_digits);
        break;
    case T(16):
        total_digits = digits_hex(v);
        total_digits = 2u + (unsigned)(num_digits > total_digits ? num_digits : total_digits);
        if(C4_LIKELY(buf.len >= total_digits))
        {
            buf.str[0] = '0';
            buf.str[1] = 'x';
            write_hex(buf.sub(2), v, num_digits);
        }
        break;
    case T(2):
        total_digits = digits_bin(v);
        total_digits = 2u + (unsigned)(num_digits > total_digits ? num_digits : total_digits);
        if(C4_LIKELY(buf.len >= total_digits))
        {
            buf.str[0] = '0';
            buf.str[1] = 'b';
            write_bin(buf.sub(2), v, num_digits);
        }
        break;
    case T(8):
        total_digits = digits_oct(v);
        total_digits = 2u + (unsigned)(num_digits > total_digits ? num_digits : total_digits);
        if(C4_LIKELY(buf.len >= total_digits))
        {
            buf.str[0] = '0';
            buf.str[1] = 'o';
            write_oct(buf.sub(2), v, num_digits);
        }
        break;
    }
    return total_digits;
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** Convert a trimmed string to a signed integral value. The input
 * string can be formatted as decimal, binary (prefix 0b or 0B), octal
 * (prefix 0o or 0O) or hexadecimal (prefix 0x or 0X). Strings with
 * leading zeroes are considered as decimal and not octal (unlike the
 * C/C++ convention). Every character in the input string is read for
 * the conversion; the input string must not contain any leading or
 * trailing whitespace.
 *
 * @return true if the conversion was successful.
 *
 * @note overflow is not detected: the return status is true even if
 * the conversion would return a value outside of the type's range, in
 * which case the result will wrap around the type's range.
 * This is similar to native behavior.
 *
 * @note a positive sign is not accepted. ie, the string must not
 * start with '+'
 *
 * @see atoi_first() if the string is not trimmed to the value to read. */
template<class T>
C4_ALWAYS_INLINE bool atoi(csubstr str, T * C4_RESTRICT v) noexcept
{
    C4_STATIC_ASSERT(std::is_integral<T>::value);
    C4_STATIC_ASSERT(std::is_signed<T>::value);

    if(C4_UNLIKELY(str.len == 0))
        return false;

    C4_ASSERT(str.str[0] != '+');

    T sign = 1;
    size_t start = 0;
    if(str.str[0] == '-')
    {
        if(C4_UNLIKELY(str.len == ++start))
            return false;
        sign = -1;
    }

    bool parsed_ok = true;
    if(str.str[start] != '0') // this should be the common case, so put it first
    {
        parsed_ok = read_dec(str.sub(start), v);
    }
    else if(str.len > start + 1)
    {
        // starts with 0: is it 0x, 0o, 0b?
        const char pfx = str.str[start + 1];
        if(pfx == 'x' || pfx == 'X')
            parsed_ok = str.len > start + 2 && read_hex(str.sub(start + 2), v);
        else if(pfx == 'b' || pfx == 'B')
            parsed_ok = str.len > start + 2 && read_bin(str.sub(start + 2), v);
        else if(pfx == 'o' || pfx == 'O')
            parsed_ok = str.len > start + 2 && read_oct(str.sub(start + 2), v);
        else
            parsed_ok = read_dec(str.sub(start + 1), v);
    }
    else
    {
        parsed_ok = read_dec(str.sub(start), v);
    }
    if(C4_LIKELY(parsed_ok))
        *v *= sign;
    return parsed_ok;
}


/** Select the next range of characters in the string that can be parsed
 * as a signed integral value, and convert it using atoi(). Leading
 * whitespace (space, newline, tabs) is skipped.
 * @return the number of characters read for conversion, or csubstr::npos if the conversion failed
 * @see atoi() if the string is already trimmed to the value to read.
 * @see csubstr::first_int_span() */
template<class T>
C4_ALWAYS_INLINE size_t atoi_first(csubstr str, T * C4_RESTRICT v)
{
    csubstr trimmed = str.first_int_span();
    if(trimmed.len == 0)
        return csubstr::npos;
    if(atoi(trimmed, v))
        return static_cast<size_t>(trimmed.end() - str.begin());
    return csubstr::npos;
}


//-----------------------------------------------------------------------------

/** Convert a trimmed string to an unsigned integral value. The string can be
 * formatted as decimal, binary (prefix 0b or 0B), octal (prefix 0o or 0O)
 * or hexadecimal (prefix 0x or 0X). Every character in the input string is read
 * for the conversion; it must not contain any leading or trailing whitespace.
 *
 * @return true if the conversion was successful.
 *
 * @note overflow is not detected: the return status is true even if
 * the conversion would return a value outside of the type's range, in
 * which case the result will wrap around the type's range.
 *
 * @note If the string has a minus character, the return status
 * will be false.
 *
 * @see atou_first() if the string is not trimmed to the value to read. */
template<class T>
bool atou(csubstr str, T * C4_RESTRICT v) noexcept
{
    C4_STATIC_ASSERT(std::is_integral<T>::value);

    if(C4_UNLIKELY(str.len == 0 || str.front() == '-'))
        return false;

    bool parsed_ok = true;
    if(str.str[0] != '0')
    {
        parsed_ok = read_dec(str, v);
    }
    else
    {
        if(str.len > 1)
        {
            const char pfx = str.str[1];
            if(pfx == 'x' || pfx == 'X')
                parsed_ok = str.len > 2 && read_hex(str.sub(2), v);
            else if(pfx == 'b' || pfx == 'B')
                parsed_ok = str.len > 2 && read_bin(str.sub(2), v);
            else if(pfx == 'o' || pfx == 'O')
                parsed_ok = str.len > 2 && read_oct(str.sub(2), v);
            else
                parsed_ok = read_dec(str, v);
        }
        else
        {
            *v = 0; // we know the first character is 0
        }
    }
    return parsed_ok;
}


/** Select the next range of characters in the string that can be parsed
 * as an unsigned integral value, and convert it using atou(). Leading
 * whitespace (space, newline, tabs) is skipped.
 * @return the number of characters read for conversion, or csubstr::npos if the conversion faileds
 * @see atou() if the string is already trimmed to the value to read.
 * @see csubstr::first_uint_span() */
template<class T>
C4_ALWAYS_INLINE size_t atou_first(csubstr str, T *v)
{
    csubstr trimmed = str.first_uint_span();
    if(trimmed.len == 0)
        return csubstr::npos;
    if(atou(trimmed, v))
        return static_cast<size_t>(trimmed.end() - str.begin());
    return csubstr::npos;
}


#ifdef _MSC_VER
#   pragma warning(pop)
#elif defined(__clang__)
#   pragma clang diagnostic pop
#elif defined(__GNUC__)
#   pragma GCC diagnostic pop
#endif


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
namespace detail {
inline bool check_overflow(csubstr str, csubstr limit) noexcept
{
    if(str.len == limit.len)
    {
        for(size_t i = 0; i < limit.len; ++i)
        {
            if(str[i] < limit[i])
                return false;
            else if(str[i] > limit[i])
                return true;
        }
        return false;
    }
    else
        return str.len > limit.len;
}
} // namespace detail


/** Test if the following string would overflow when converted to associated
 * types.
 * @return true if number will overflow, false if it fits (or doesn't parse)
 */
template<class T>
auto overflows(csubstr str) noexcept
    -> typename std::enable_if<std::is_unsigned<T>::value, bool>::type
{
    C4_STATIC_ASSERT(std::is_integral<T>::value);

    if(C4_UNLIKELY(str.len == 0))
    {
        return false;
    }
    else if(str.str[0] == '0')
    {
        if (str.len == 1)
            return false;
        switch (str.str[1])
        {
            case 'x':
            case 'X':
            {
                size_t fno = str.first_not_of('0', 2);
                if (fno == csubstr::npos)
                    return false;
                return !(str.len <= fno + (sizeof(T) * 2));
            }
            case 'b':
            case 'B':
            {
                size_t fno = str.first_not_of('0', 2);
                if (fno == csubstr::npos)
                    return false;
                return !(str.len <= fno +(sizeof(T) * 8));
            }
            case 'o':
            case 'O':
            {
                size_t fno = str.first_not_of('0', 2);
                if(fno == csubstr::npos)
                    return false;
                return detail::charconv_digits<T>::is_oct_overflow(str.sub(fno));
            }
            default:
            {
                size_t fno = str.first_not_of('0', 1);
                if(fno == csubstr::npos)
                    return false;
                return detail::check_overflow(str.sub(fno), detail::charconv_digits<T>::max_value_dec());
            }
        }
    }
    else if(C4_UNLIKELY(str[0] == '-'))
    {
        return true;
    }
    else
    {
        return detail::check_overflow(str, detail::charconv_digits<T>::max_value_dec());
    }
}


/** Test if the following string would overflow when converted to associated
 * types.
 * @return true if number will overflow, false if it fits (or doesn't parse)
 */
template<class T>
auto overflows(csubstr str)
    -> typename std::enable_if<std::is_signed<T>::value, bool>::type
{
    C4_STATIC_ASSERT(std::is_integral<T>::value);
    if(C4_UNLIKELY(str.len == 0))
        return false;
    if(str.str[0] == '-')
    {
        if(str.str[1] == '0')
        {
            if(str.len == 2)
                return false;
            switch(str.str[2])
            {
                case 'x':
                case 'X':
                {
                    size_t fno = str.first_not_of('0', 3);
                    if (fno == csubstr::npos)
                        return false;
                    return detail::check_overflow(str.sub(fno), detail::charconv_digits<T>::min_value_hex());
                }
                case 'b':
                case 'B':
                {
                    size_t fno = str.first_not_of('0', 3);
                    if (fno == csubstr::npos)
                        return false;
                    return detail::check_overflow(str.sub(fno), detail::charconv_digits<T>::min_value_bin());
                }
                case 'o':
                case 'O':
                {
                    size_t fno = str.first_not_of('0', 3);
                    if(fno == csubstr::npos)
                        return false;
                    return detail::check_overflow(str.sub(fno), detail::charconv_digits<T>::min_value_oct());
                }
                default:
                {
                    size_t fno = str.first_not_of('0', 2);
                    if(fno == csubstr::npos)
                        return false;
                    return detail::check_overflow(str.sub(fno), detail::charconv_digits<T>::min_value_dec());
                }
            }
        }
        else
            return detail::check_overflow(str.sub(1), detail::charconv_digits<T>::min_value_dec());
    }
    else if(str.str[0] == '0')
    {
        if (str.len == 1)
            return false;
        switch(str.str[1])
        {
            case 'x':
            case 'X':
            {
                size_t fno = str.first_not_of('0', 2);
                if (fno == csubstr::npos)
                    return false;
                const size_t len = str.len - fno;
                return !((len < sizeof (T) * 2) || (len == sizeof(T) * 2 && str[fno] <= '7'));
            }
            case 'b':
            case 'B':
            {
                size_t fno = str.first_not_of('0', 2);
                if (fno == csubstr::npos)
                    return false;
                return !(str.len <= fno + (sizeof(T) * 8 - 1));
            }
            case 'o':
            case 'O':
            {
                size_t fno = str.first_not_of('0', 2);
                if(fno == csubstr::npos)
                    return false;
                return detail::charconv_digits<T>::is_oct_overflow(str.sub(fno));
            }
            default:
            {
                size_t fno = str.first_not_of('0', 1);
                if(fno == csubstr::npos)
                    return false;
                return detail::check_overflow(str.sub(fno), detail::charconv_digits<T>::max_value_dec());
            }
        }
    }
    else
        return detail::check_overflow(str, detail::charconv_digits<T>::max_value_dec());
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

namespace detail {


#if (!C4CORE_HAVE_STD_FROMCHARS)
/** @see http://www.exploringbinary.com/ for many good examples on float-str conversion */
template<size_t N>
void get_real_format_str(char (& C4_RESTRICT fmt)[N], int precision, RealFormat_e formatting, const char* length_modifier="")
{
    int iret;
    if(precision == -1)
        iret = snprintf(fmt, sizeof(fmt), "%%%s%c", length_modifier, formatting);
    else if(precision == 0)
        iret = snprintf(fmt, sizeof(fmt), "%%.%s%c", length_modifier, formatting);
    else
        iret = snprintf(fmt, sizeof(fmt), "%%.%d%s%c", precision, length_modifier, formatting);
    C4_ASSERT(iret >= 2 && size_t(iret) < sizeof(fmt));
    C4_UNUSED(iret);
}


/** @todo we're depending on snprintf()/sscanf() for converting to/from
 * floating point numbers. Apparently, this increases the binary size
 * by a considerable amount. There are some lightweight printf
 * implementations:
 *
 * @see http://www.sparetimelabs.com/tinyprintf/tinyprintf.php (BSD)
 * @see https://github.com/weiss/c99-snprintf
 * @see https://github.com/nothings/stb/blob/master/stb_sprintf.h
 * @see http://www.exploringbinary.com/
 * @see https://blog.benoitblanchon.fr/lightweight-float-to-string/
 * @see http://www.ryanjuckett.com/programming/printing-floating-point-numbers/
 */
template<class T>
size_t print_one(substr str, const char* full_fmt, T v)
{
#ifdef _MSC_VER
    /** use _snprintf() to prevent early termination of the output
     * for writing the null character at the last position
     * @see https://msdn.microsoft.com/en-us/library/2ts7cx93.aspx */
    int iret = _snprintf(str.str, str.len, full_fmt, v);
    if(iret < 0)
    {
        /* when buf.len is not enough, VS returns a negative value.
         * so call it again with a negative value for getting an
         * actual length of the string */
        iret = snprintf(nullptr, 0, full_fmt, v);
        C4_ASSERT(iret > 0);
    }
    size_t ret = (size_t) iret;
    return ret;
#else
    int iret = snprintf(str.str, str.len, full_fmt, v);
    C4_ASSERT(iret >= 0);
    size_t ret = (size_t) iret;
    if(ret >= str.len)
        ++ret; /* snprintf() reserves the last character to write \0 */
    return ret;
#endif
}
#endif // (!C4CORE_HAVE_STD_FROMCHARS)


#if (!C4CORE_HAVE_STD_FROMCHARS) && (!C4CORE_HAVE_FAST_FLOAT)
/** scans a string using the given type format, while at the same time
 * allowing non-null-terminated strings AND guaranteeing that the given
 * string length is strictly respected, so that no buffer overflows
 * might occur. */
template<typename T>
inline size_t scan_one(csubstr str, const char *type_fmt, T *v)
{
    /* snscanf() is absolutely needed here as we must be sure that
     * str.len is strictly respected, because substr is
     * generally not null-terminated.
     *
     * Alas, there is no snscanf().
     *
     * So we fake it by using a dynamic format with an explicit
     * field size set to the length of the given span.
     * This trick is taken from:
     * https://stackoverflow.com/a/18368910/5875572 */

    /* this is the actual format we'll use for scanning */
    char fmt[16];

    /* write the length into it. Eg "%12f".
     * Also, get the number of characters read from the string.
     * So the final format ends up as "%12f%n"*/
    int iret = std::snprintf(fmt, sizeof(fmt), "%%" "%zu" "%s" "%%n", str.len, type_fmt);
    /* no nasty surprises, please! */
    C4_ASSERT(iret >= 0 && size_t(iret) < C4_COUNTOF(fmt));

    /* now we scan with confidence that the span length is respected */
    int num_chars;
    iret = std::sscanf(str.str, fmt, v, &num_chars);
    /* scanf returns the number of successful conversions */
    if(iret != 1) return csubstr::npos;
    C4_ASSERT(num_chars >= 0);
    return (size_t)(num_chars);
}
#endif // (!C4CORE_HAVE_STD_FROMCHARS) && (!C4CORE_HAVE_FAST_FLOAT)


#if C4CORE_HAVE_STD_TOCHARS
template<class T>
C4_ALWAYS_INLINE size_t rtoa(substr buf, T v, int precision=-1, RealFormat_e formatting=FTOA_FLEX) noexcept
{
    std::to_chars_result result;
    size_t pos = 0;
    if(formatting == FTOA_HEXA)
    {
        if(buf.len > size_t(2))
        {
            buf.str[0] = '0';
            buf.str[1] = 'x';
        }
        pos += size_t(2);
    }
    if(precision == -1)
        result = std::to_chars(buf.str + pos, buf.str + buf.len, v, (std::chars_format)formatting);
    else
        result = std::to_chars(buf.str + pos, buf.str + buf.len, v, (std::chars_format)formatting, precision);
    if(result.ec == std::errc())
    {
        // all good, no errors.
        C4_ASSERT(result.ptr >= buf.str);
        ptrdiff_t delta = result.ptr - buf.str;
        return static_cast<size_t>(delta);
    }
    C4_ASSERT(result.ec == std::errc::value_too_large);
    // This is unfortunate.
    //
    // When the result can't fit in the given buffer,
    // std::to_chars() returns the end pointer it was originally
    // given, which is useless because here we would like to know
    // _exactly_ how many characters the buffer must have to fit
    // the result.
    //
    // So we take the pessimistic view, and assume as many digits
    // as could ever be required:
    size_t ret = static_cast<size_t>(std::numeric_limits<T>::max_digits10);
    return ret > buf.len ? ret : buf.len + 1;
}
#endif // C4CORE_HAVE_STD_TOCHARS


#if C4CORE_HAVE_FAST_FLOAT
template<class T>
C4_ALWAYS_INLINE bool scan_rhex(csubstr s, T *C4_RESTRICT val) noexcept
{
    C4_ASSERT(s.len > 0);
    C4_ASSERT(s.str[0] != '-');
    C4_ASSERT(s.str[0] != '+');
    C4_ASSERT(!s.begins_with("0x"));
    C4_ASSERT(!s.begins_with("0X"));
    size_t pos = 0;
    // integer part
    for( ; pos < s.len; ++pos)
    {
        const char c = s.str[pos];
        if(c >= '0' && c <= '9')
            *val = *val * T(16) + T(c - '0');
        else if(c >= 'a' && c <= 'f')
            *val = *val * T(16) + T(c - 'a');
        else if(c >= 'A' && c <= 'F')
            *val = *val * T(16) + T(c - 'A');
        else if(c == '.')
        {
            ++pos;
            break; // follow on to mantissa
        }
        else if(c == 'p' || c == 'P')
        {
            ++pos;
            goto power; // no mantissa given, jump to power
        }
        else
        {
            return false;
        }
    }
    // mantissa
    {
        // 0.0625 == 1/16 == value of first digit after the comma
        for(T digit = T(0.0625); pos < s.len; ++pos, digit /= T(16))
        {
            const char c = s.str[pos];
            if(c >= '0' && c <= '9')
                *val += digit * T(c - '0');
            else if(c >= 'a' && c <= 'f')
                *val += digit * T(c - 'a');
            else if(c >= 'A' && c <= 'F')
                *val += digit * T(c - 'A');
            else if(c == 'p' || c == 'P')
            {
                ++pos;
                goto power; // mantissa finished, jump to power
            }
            else
            {
                return false;
            }
        }
    }
    return true;
power:
    if(C4_LIKELY(pos < s.len))
    {
        if(s.str[pos] == '+') // atoi() cannot handle a leading '+'
            ++pos;
        if(C4_LIKELY(pos < s.len))
        {
            int16_t powval = {};
            if(C4_LIKELY(atoi(s.sub(pos), &powval)))
            {
                *val *= ipow<T, int16_t, 16>(powval);
                return true;
            }
        }
    }
    return false;
}
#endif

} // namespace detail


#undef _c4appendhex
#undef _c4append


/** Convert a single-precision real number to string.  The string will
 * in general be NOT null-terminated.  For FTOA_FLEX, \p precision is
 * the number of significand digits. Otherwise \p precision is the
 * number of decimals. It is safe to call this function with an empty
 * or too-small buffer.
 *
 * @return the size of the buffer needed to write the number
 */
C4_ALWAYS_INLINE size_t ftoa(substr str, float v, int precision=-1, RealFormat_e formatting=FTOA_FLEX) noexcept
{
#if C4CORE_HAVE_STD_TOCHARS
    return detail::rtoa(str, v, precision, formatting);
#else
    char fmt[16];
    detail::get_real_format_str(fmt, precision, formatting, /*length_modifier*/"");
    return detail::print_one(str, fmt, v);
#endif
}


/** Convert a double-precision real number to string.  The string will
 * in general be NOT null-terminated.  For FTOA_FLEX, \p precision is
 * the number of significand digits. Otherwise \p precision is the
 * number of decimals. It is safe to call this function with an empty
 * or too-small buffer.
 *
 * @return the size of the buffer needed to write the number
 */
C4_ALWAYS_INLINE size_t dtoa(substr str, double v, int precision=-1, RealFormat_e formatting=FTOA_FLEX) noexcept
{
#if C4CORE_HAVE_STD_TOCHARS
    return detail::rtoa(str, v, precision, formatting);
#else
    char fmt[16];
    detail::get_real_format_str(fmt, precision, formatting, /*length_modifier*/"l");
    return detail::print_one(str, fmt, v);
#endif
}


/** Convert a string to a single precision real number.
 * The input string must be trimmed to the value, ie
 * no leading or trailing whitespace can be present.
 * @return true iff the conversion succeeded
 * @see atof_first() if the string is not trimmed
 */
C4_ALWAYS_INLINE bool atof(csubstr str, float * C4_RESTRICT v) noexcept
{
    C4_ASSERT(str.len > 0);
    C4_ASSERT(str.triml(" \r\t\n").len == str.len);
#if C4CORE_HAVE_FAST_FLOAT
    // fastfloat cannot parse hexadecimal floats
    bool isneg = (str.str[0] == '-');
    csubstr rem = str.sub(isneg || str.str[0] == '+');
    if(!(rem.len >= 2 && (rem.str[0] == '0' && (rem.str[1] == 'x' || rem.str[1] == 'X'))))
    {
        fast_float::from_chars_result result;
        result = fast_float::from_chars(str.str, str.str + str.len, *v);
        return result.ec == std::errc();
    }
    else if(detail::scan_rhex(rem.sub(2), v))
    {
        *v *= isneg ? -1.f : 1.f;
        return true;
    }
    return false;
#elif C4CORE_HAVE_STD_FROMCHARS
    std::from_chars_result result;
    result = std::from_chars(str.str, str.str + str.len, *v);
    return result.ec == std::errc();
#else
    csubstr rem = str.sub(str.str[0] == '-' || str.str[0] == '+');
    if(!(rem.len >= 2 && (rem.str[0] == '0' && (rem.str[1] == 'x' || rem.str[1] == 'X'))))
        return detail::scan_one(str, "f", v) != csubstr::npos;
    else
        return detail::scan_one(str, "a", v) != csubstr::npos;
#endif
}


/** Convert a string to a double precision real number.
 * The input string must be trimmed to the value, ie
 * no leading or trailing whitespace can be present.
 * @return true iff the conversion succeeded
 * @see atod_first() if the string is not trimmed
 */
C4_ALWAYS_INLINE bool atod(csubstr str, double * C4_RESTRICT v) noexcept
{
    C4_ASSERT(str.triml(" \r\t\n").len == str.len);
#if C4CORE_HAVE_FAST_FLOAT
    // fastfloat cannot parse hexadecimal floats
    bool isneg = (str.str[0] == '-');
    csubstr rem = str.sub(isneg || str.str[0] == '+');
    if(!(rem.len >= 2 && (rem.str[0] == '0' && (rem.str[1] == 'x' || rem.str[1] == 'X'))))
    {
        fast_float::from_chars_result result;
        result = fast_float::from_chars(str.str, str.str + str.len, *v);
        return result.ec == std::errc();
    }
    else if(detail::scan_rhex(rem.sub(2), v))
    {
        *v *= isneg ? -1. : 1.;
        return true;
    }
    return false;
#elif C4CORE_HAVE_STD_FROMCHARS
    std::from_chars_result result;
    result = std::from_chars(str.str, str.str + str.len, *v);
    return result.ec == std::errc();
#else
    csubstr rem = str.sub(str.str[0] == '-' || str.str[0] == '+');
    if(!(rem.len >= 2 && (rem.str[0] == '0' && (rem.str[1] == 'x' || rem.str[1] == 'X'))))
        return detail::scan_one(str, "lf", v) != csubstr::npos;
    else
        return detail::scan_one(str, "la", v) != csubstr::npos;
#endif
}


/** Convert a string to a single precision real number.
 * Leading whitespace is skipped until valid characters are found.
 * @return the number of characters read from the string, or npos if
 * conversion was not successful or if the string was empty */
inline size_t atof_first(csubstr str, float * C4_RESTRICT v) noexcept
{
    csubstr trimmed = str.first_real_span();
    if(trimmed.len == 0)
        return csubstr::npos;
    if(atof(trimmed, v))
        return static_cast<size_t>(trimmed.end() - str.begin());
    return csubstr::npos;
}


/** Convert a string to a double precision real number.
 * Leading whitespace is skipped until valid characters are found.
 * @return the number of characters read from the string, or npos if
 * conversion was not successful or if the string was empty */
inline size_t atod_first(csubstr str, double * C4_RESTRICT v) noexcept
{
    csubstr trimmed = str.first_real_span();
    if(trimmed.len == 0)
        return csubstr::npos;
    if(atod(trimmed, v))
        return static_cast<size_t>(trimmed.end() - str.begin());
    return csubstr::npos;
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
// generic versions

C4_ALWAYS_INLINE size_t xtoa(substr s,  uint8_t v) noexcept { return write_dec(s, v); }
C4_ALWAYS_INLINE size_t xtoa(substr s, uint16_t v) noexcept { return write_dec(s, v); }
C4_ALWAYS_INLINE size_t xtoa(substr s, uint32_t v) noexcept { return write_dec(s, v); }
C4_ALWAYS_INLINE size_t xtoa(substr s, uint64_t v) noexcept { return write_dec(s, v); }
C4_ALWAYS_INLINE size_t xtoa(substr s,   int8_t v) noexcept { return itoa(s, v); }
C4_ALWAYS_INLINE size_t xtoa(substr s,  int16_t v) noexcept { return itoa(s, v); }
C4_ALWAYS_INLINE size_t xtoa(substr s,  int32_t v) noexcept { return itoa(s, v); }
C4_ALWAYS_INLINE size_t xtoa(substr s,  int64_t v) noexcept { return itoa(s, v); }
C4_ALWAYS_INLINE size_t xtoa(substr s,    float v) noexcept { return ftoa(s, v); }
C4_ALWAYS_INLINE size_t xtoa(substr s,   double v) noexcept { return dtoa(s, v); }

C4_ALWAYS_INLINE size_t xtoa(substr s,  uint8_t v,  uint8_t radix) noexcept { return utoa(s, v, radix); }
C4_ALWAYS_INLINE size_t xtoa(substr s, uint16_t v, uint16_t radix) noexcept { return utoa(s, v, radix); }
C4_ALWAYS_INLINE size_t xtoa(substr s, uint32_t v, uint32_t radix) noexcept { return utoa(s, v, radix); }
C4_ALWAYS_INLINE size_t xtoa(substr s, uint64_t v, uint64_t radix) noexcept { return utoa(s, v, radix); }
C4_ALWAYS_INLINE size_t xtoa(substr s,   int8_t v,   int8_t radix) noexcept { return itoa(s, v, radix); }
C4_ALWAYS_INLINE size_t xtoa(substr s,  int16_t v,  int16_t radix) noexcept { return itoa(s, v, radix); }
C4_ALWAYS_INLINE size_t xtoa(substr s,  int32_t v,  int32_t radix) noexcept { return itoa(s, v, radix); }
C4_ALWAYS_INLINE size_t xtoa(substr s,  int64_t v,  int64_t radix) noexcept { return itoa(s, v, radix); }

C4_ALWAYS_INLINE size_t xtoa(substr s,  uint8_t v,  uint8_t radix, size_t num_digits) noexcept { return utoa(s, v, radix, num_digits); }
C4_ALWAYS_INLINE size_t xtoa(substr s, uint16_t v, uint16_t radix, size_t num_digits) noexcept { return utoa(s, v, radix, num_digits); }
C4_ALWAYS_INLINE size_t xtoa(substr s, uint32_t v, uint32_t radix, size_t num_digits) noexcept { return utoa(s, v, radix, num_digits); }
C4_ALWAYS_INLINE size_t xtoa(substr s, uint64_t v, uint64_t radix, size_t num_digits) noexcept { return utoa(s, v, radix, num_digits); }
C4_ALWAYS_INLINE size_t xtoa(substr s,   int8_t v,   int8_t radix, size_t num_digits) noexcept { return itoa(s, v, radix, num_digits); }
C4_ALWAYS_INLINE size_t xtoa(substr s,  int16_t v,  int16_t radix, size_t num_digits) noexcept { return itoa(s, v, radix, num_digits); }
C4_ALWAYS_INLINE size_t xtoa(substr s,  int32_t v,  int32_t radix, size_t num_digits) noexcept { return itoa(s, v, radix, num_digits); }
C4_ALWAYS_INLINE size_t xtoa(substr s,  int64_t v,  int64_t radix, size_t num_digits) noexcept { return itoa(s, v, radix, num_digits); }

C4_ALWAYS_INLINE size_t xtoa(substr s,  float v, int precision, RealFormat_e formatting=FTOA_FLEX) noexcept { return ftoa(s, v, precision, formatting); }
C4_ALWAYS_INLINE size_t xtoa(substr s, double v, int precision, RealFormat_e formatting=FTOA_FLEX) noexcept { return dtoa(s, v, precision, formatting); }

C4_ALWAYS_INLINE bool atox(csubstr s,  uint8_t *C4_RESTRICT v) noexcept { return atou(s, v); }
C4_ALWAYS_INLINE bool atox(csubstr s, uint16_t *C4_RESTRICT v) noexcept { return atou(s, v); }
C4_ALWAYS_INLINE bool atox(csubstr s, uint32_t *C4_RESTRICT v) noexcept { return atou(s, v); }
C4_ALWAYS_INLINE bool atox(csubstr s, uint64_t *C4_RESTRICT v) noexcept { return atou(s, v); }
C4_ALWAYS_INLINE bool atox(csubstr s,   int8_t *C4_RESTRICT v) noexcept { return atoi(s, v); }
C4_ALWAYS_INLINE bool atox(csubstr s,  int16_t *C4_RESTRICT v) noexcept { return atoi(s, v); }
C4_ALWAYS_INLINE bool atox(csubstr s,  int32_t *C4_RESTRICT v) noexcept { return atoi(s, v); }
C4_ALWAYS_INLINE bool atox(csubstr s,  int64_t *C4_RESTRICT v) noexcept { return atoi(s, v); }
C4_ALWAYS_INLINE bool atox(csubstr s,    float *C4_RESTRICT v) noexcept { return atof(s, v); }
C4_ALWAYS_INLINE bool atox(csubstr s,   double *C4_RESTRICT v) noexcept { return atod(s, v); }

C4_ALWAYS_INLINE size_t to_chars(substr buf,  uint8_t v) noexcept { return write_dec(buf, v); }
C4_ALWAYS_INLINE size_t to_chars(substr buf, uint16_t v) noexcept { return write_dec(buf, v); }
C4_ALWAYS_INLINE size_t to_chars(substr buf, uint32_t v) noexcept { return write_dec(buf, v); }
C4_ALWAYS_INLINE size_t to_chars(substr buf, uint64_t v) noexcept { return write_dec(buf, v); }
C4_ALWAYS_INLINE size_t to_chars(substr buf,   int8_t v) noexcept { return itoa(buf, v); }
C4_ALWAYS_INLINE size_t to_chars(substr buf,  int16_t v) noexcept { return itoa(buf, v); }
C4_ALWAYS_INLINE size_t to_chars(substr buf,  int32_t v) noexcept { return itoa(buf, v); }
C4_ALWAYS_INLINE size_t to_chars(substr buf,  int64_t v) noexcept { return itoa(buf, v); }
C4_ALWAYS_INLINE size_t to_chars(substr buf,    float v) noexcept { return ftoa(buf, v); }
C4_ALWAYS_INLINE size_t to_chars(substr buf,   double v) noexcept { return dtoa(buf, v); }

C4_ALWAYS_INLINE bool from_chars(csubstr buf,  uint8_t *C4_RESTRICT v) noexcept { return atou(buf, v); }
C4_ALWAYS_INLINE bool from_chars(csubstr buf, uint16_t *C4_RESTRICT v) noexcept { return atou(buf, v); }
C4_ALWAYS_INLINE bool from_chars(csubstr buf, uint32_t *C4_RESTRICT v) noexcept { return atou(buf, v); }
C4_ALWAYS_INLINE bool from_chars(csubstr buf, uint64_t *C4_RESTRICT v) noexcept { return atou(buf, v); }
C4_ALWAYS_INLINE bool from_chars(csubstr buf,   int8_t *C4_RESTRICT v) noexcept { return atoi(buf, v); }
C4_ALWAYS_INLINE bool from_chars(csubstr buf,  int16_t *C4_RESTRICT v) noexcept { return atoi(buf, v); }
C4_ALWAYS_INLINE bool from_chars(csubstr buf,  int32_t *C4_RESTRICT v) noexcept { return atoi(buf, v); }
C4_ALWAYS_INLINE bool from_chars(csubstr buf,  int64_t *C4_RESTRICT v) noexcept { return atoi(buf, v); }
C4_ALWAYS_INLINE bool from_chars(csubstr buf,    float *C4_RESTRICT v) noexcept { return atof(buf, v); }
C4_ALWAYS_INLINE bool from_chars(csubstr buf,   double *C4_RESTRICT v) noexcept { return atod(buf, v); }

C4_ALWAYS_INLINE size_t from_chars_first(csubstr buf,  uint8_t *C4_RESTRICT v) noexcept { return atou_first(buf, v); }
C4_ALWAYS_INLINE size_t from_chars_first(csubstr buf, uint16_t *C4_RESTRICT v) noexcept { return atou_first(buf, v); }
C4_ALWAYS_INLINE size_t from_chars_first(csubstr buf, uint32_t *C4_RESTRICT v) noexcept { return atou_first(buf, v); }
C4_ALWAYS_INLINE size_t from_chars_first(csubstr buf, uint64_t *C4_RESTRICT v) noexcept { return atou_first(buf, v); }
C4_ALWAYS_INLINE size_t from_chars_first(csubstr buf,   int8_t *C4_RESTRICT v) noexcept { return atoi_first(buf, v); }
C4_ALWAYS_INLINE size_t from_chars_first(csubstr buf,  int16_t *C4_RESTRICT v) noexcept { return atoi_first(buf, v); }
C4_ALWAYS_INLINE size_t from_chars_first(csubstr buf,  int32_t *C4_RESTRICT v) noexcept { return atoi_first(buf, v); }
C4_ALWAYS_INLINE size_t from_chars_first(csubstr buf,  int64_t *C4_RESTRICT v) noexcept { return atoi_first(buf, v); }
C4_ALWAYS_INLINE size_t from_chars_first(csubstr buf,    float *C4_RESTRICT v) noexcept { return atof_first(buf, v); }
C4_ALWAYS_INLINE size_t from_chars_first(csubstr buf,   double *C4_RESTRICT v) noexcept { return atod_first(buf, v); }


//-----------------------------------------------------------------------------
// on some platforms, (unsigned) int and (unsigned) long
// are not any of the fixed length types above

#define _C4_IF_NOT_FIXED_LENGTH_I(T, ty) C4_ALWAYS_INLINE typename std::enable_if<std::  is_signed<T>::value && !is_fixed_length<T>::value_i, ty>
#define _C4_IF_NOT_FIXED_LENGTH_U(T, ty) C4_ALWAYS_INLINE typename std::enable_if<std::is_unsigned<T>::value && !is_fixed_length<T>::value_u, ty>

template <class T> _C4_IF_NOT_FIXED_LENGTH_I(T, size_t)::type xtoa(substr buf, T v) noexcept { return itoa(buf, v); }
template <class T> _C4_IF_NOT_FIXED_LENGTH_U(T, size_t)::type xtoa(substr buf, T v) noexcept { return write_dec(buf, v); }

template <class T> _C4_IF_NOT_FIXED_LENGTH_I(T, bool  )::type atox(csubstr buf, T *C4_RESTRICT v) noexcept { return atoi(buf, v); }
template <class T> _C4_IF_NOT_FIXED_LENGTH_U(T, bool  )::type atox(csubstr buf, T *C4_RESTRICT v) noexcept { return atou(buf, v); }

template <class T> _C4_IF_NOT_FIXED_LENGTH_I(T, size_t)::type to_chars(substr buf, T v) noexcept { return itoa(buf, v); }
template <class T> _C4_IF_NOT_FIXED_LENGTH_U(T, size_t)::type to_chars(substr buf, T v) noexcept { return write_dec(buf, v); }

template <class T> _C4_IF_NOT_FIXED_LENGTH_I(T, bool  )::type from_chars(csubstr buf, T *C4_RESTRICT v) noexcept { return atoi(buf, v); }
template <class T> _C4_IF_NOT_FIXED_LENGTH_U(T, bool  )::type from_chars(csubstr buf, T *C4_RESTRICT v) noexcept { return atou(buf, v); }

template <class T> _C4_IF_NOT_FIXED_LENGTH_I(T, size_t)::type from_chars_first(csubstr buf, T *C4_RESTRICT v) noexcept { return atoi_first(buf, v); }
template <class T> _C4_IF_NOT_FIXED_LENGTH_U(T, size_t)::type from_chars_first(csubstr buf, T *C4_RESTRICT v) noexcept { return atou_first(buf, v); }

#undef _C4_IF_NOT_FIXED_LENGTH_I
#undef _C4_IF_NOT_FIXED_LENGTH_U


//-----------------------------------------------------------------------------
// for pointers

template <class T> C4_ALWAYS_INLINE size_t xtoa(substr s, T *v) noexcept { return itoa(s, (intptr_t)v, (intptr_t)16); }
template <class T> C4_ALWAYS_INLINE bool   atox(csubstr s, T **v) noexcept { intptr_t tmp; bool ret = atox(s, &tmp); if(ret) { *v = (T*)tmp; } return ret; }
template <class T> C4_ALWAYS_INLINE size_t to_chars(substr s, T *v) noexcept { return itoa(s, (intptr_t)v, (intptr_t)16); }
template <class T> C4_ALWAYS_INLINE bool   from_chars(csubstr buf, T **v) noexcept { intptr_t tmp; bool ret = from_chars(buf, &tmp); if(ret) { *v = (T*)tmp; } return ret; }
template <class T> C4_ALWAYS_INLINE size_t from_chars_first(csubstr buf, T **v) noexcept { intptr_t tmp; bool ret = from_chars_first(buf, &tmp); if(ret) { *v = (T*)tmp; } return ret; }


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
/** call to_chars() and return a substr consisting of the
 * written portion of the input buffer. Ie, same as to_chars(),
 * but return a substr instead of a size_t.
 *
 * @see to_chars() */
template<class T>
C4_ALWAYS_INLINE substr to_chars_sub(substr buf, T const& C4_RESTRICT v) noexcept
{
    size_t sz = to_chars(buf, v);
    return buf.left_of(sz <= buf.len ? sz : buf.len);
}

//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
// bool implementation

C4_ALWAYS_INLINE size_t to_chars(substr buf, bool v) noexcept
{
    int val = v;
    return to_chars(buf, val);
}

inline bool from_chars(csubstr buf, bool * C4_RESTRICT v) noexcept
{
    if(buf == '0')
    {
        *v = false; return true;
    }
    else if(buf == '1')
    {
        *v = true; return true;
    }
    else if(buf == "false")
    {
        *v = false; return true;
    }
    else if(buf == "true")
    {
        *v = true; return true;
    }
    else if(buf == "False")
    {
        *v = false; return true;
    }
    else if(buf == "True")
    {
        *v = true; return true;
    }
    else if(buf == "FALSE")
    {
        *v = false; return true;
    }
    else if(buf == "TRUE")
    {
        *v = true; return true;
    }
    // fallback to c-style int bools
    int val = 0;
    bool ret = from_chars(buf, &val);
    if(C4_LIKELY(ret))
    {
        *v = (val != 0);
    }
    return ret;
}

inline size_t from_chars_first(csubstr buf, bool * C4_RESTRICT v) noexcept
{
    csubstr trimmed = buf.first_non_empty_span();
    if(trimmed.len == 0 || !from_chars(buf, v))
        return csubstr::npos;
    return trimmed.len;
}


//-----------------------------------------------------------------------------
// single-char implementation

inline size_t to_chars(substr buf, char v) noexcept
{
    if(buf.len > 0)
        buf[0] = v;
    return 1;
}

/** extract a single character from a substring
 * @note to extract a string instead and not just a single character, use the csubstr overload */
inline bool from_chars(csubstr buf, char * C4_RESTRICT v) noexcept
{
    if(buf.len != 1)
        return false;
    *v = buf[0];
    return true;
}

inline size_t from_chars_first(csubstr buf, char * C4_RESTRICT v) noexcept
{
    if(buf.len < 1)
        return csubstr::npos;
    *v = buf[0];
    return 1;
}


//-----------------------------------------------------------------------------
// csubstr implementation

inline size_t to_chars(substr buf, csubstr v) noexcept
{
    C4_ASSERT(!buf.overlaps(v));
    size_t len = buf.len < v.len ? buf.len : v.len;
    // calling memcpy with null strings is undefined behavior
    // and will wreak havoc in calling code's branches.
    // see https://github.com/biojppm/rapidyaml/pull/264#issuecomment-1262133637
    if(len)
    {
        C4_ASSERT(buf.str != nullptr);
        C4_ASSERT(v.str != nullptr);
        memcpy(buf.str, v.str, len);
    }
    return v.len;
}

inline bool from_chars(csubstr buf, csubstr *C4_RESTRICT v) noexcept
{
    *v = buf;
    return true;
}

inline size_t from_chars_first(substr buf, csubstr * C4_RESTRICT v) noexcept
{
    csubstr trimmed = buf.first_non_empty_span();
    if(trimmed.len == 0)
        return csubstr::npos;
    *v = trimmed;
    return static_cast<size_t>(trimmed.end() - buf.begin());
}


//-----------------------------------------------------------------------------
// substr

inline size_t to_chars(substr buf, substr v) noexcept
{
    C4_ASSERT(!buf.overlaps(v));
    size_t len = buf.len < v.len ? buf.len : v.len;
    // calling memcpy with null strings is undefined behavior
    // and will wreak havoc in calling code's branches.
    // see https://github.com/biojppm/rapidyaml/pull/264#issuecomment-1262133637
    if(len)
    {
        C4_ASSERT(buf.str != nullptr);
        C4_ASSERT(v.str != nullptr);
        memcpy(buf.str, v.str, len);
    }
    return v.len;
}

inline bool from_chars(csubstr buf, substr * C4_RESTRICT v) noexcept
{
    C4_ASSERT(!buf.overlaps(*v));
    // is the destination buffer wide enough?
    if(v->len >= buf.len)
    {
        // calling memcpy with null strings is undefined behavior
        // and will wreak havoc in calling code's branches.
        // see https://github.com/biojppm/rapidyaml/pull/264#issuecomment-1262133637
        if(buf.len)
        {
            C4_ASSERT(buf.str != nullptr);
            C4_ASSERT(v->str != nullptr);
            memcpy(v->str, buf.str, buf.len);
        }
        v->len = buf.len;
        return true;
    }
    return false;
}

inline size_t from_chars_first(csubstr buf, substr * C4_RESTRICT v) noexcept
{
    csubstr trimmed = buf.first_non_empty_span();
    C4_ASSERT(!trimmed.overlaps(*v));
    if(C4_UNLIKELY(trimmed.len == 0))
        return csubstr::npos;
    size_t len = trimmed.len > v->len ? v->len : trimmed.len;
    // calling memcpy with null strings is undefined behavior
    // and will wreak havoc in calling code's branches.
    // see https://github.com/biojppm/rapidyaml/pull/264#issuecomment-1262133637
    if(len)
    {
        C4_ASSERT(buf.str != nullptr);
        C4_ASSERT(v->str != nullptr);
        memcpy(v->str, trimmed.str, len);
    }
    if(C4_UNLIKELY(trimmed.len > v->len))
        return csubstr::npos;
    return static_cast<size_t>(trimmed.end() - buf.begin());
}


//-----------------------------------------------------------------------------

template<size_t N>
inline size_t to_chars(substr buf, const char (& C4_RESTRICT v)[N]) noexcept
{
    csubstr sp(v);
    return to_chars(buf, sp);
}

inline size_t to_chars(substr buf, const char * C4_RESTRICT v) noexcept
{
    return to_chars(buf, to_csubstr(v));
}

} // namespace c4

#ifdef _MSC_VER
#   pragma warning(pop)
#elif defined(__clang__)
#   pragma clang diagnostic pop
#elif defined(__GNUC__)
#   pragma GCC diagnostic pop
#endif

#endif /* _C4_CHARCONV_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/charconv.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/utf.hpp
// https://github.com/biojppm/c4core/src/c4/utf.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef C4_UTF_HPP_
#define C4_UTF_HPP_

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/language.hpp
//#include "c4/language.hpp"
#if !defined(C4_LANGUAGE_HPP_) && !defined(_C4_LANGUAGE_HPP_)
#error "amalgamate: file c4/language.hpp must have been included at this point"
#endif /* C4_LANGUAGE_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/substr_fwd.hpp
//#include "c4/substr_fwd.hpp"
#if !defined(C4_SUBSTR_FWD_HPP_) && !defined(_C4_SUBSTR_FWD_HPP_)
#error "amalgamate: file c4/substr_fwd.hpp must have been included at this point"
#endif /* C4_SUBSTR_FWD_HPP_ */

//included above:
//#include <stddef.h>
//included above:
//#include <stdint.h>

namespace c4 {

substr decode_code_point(substr out, csubstr code_point);
size_t decode_code_point(uint8_t *C4_RESTRICT buf, size_t buflen, const uint32_t code);

} // namespace c4

#endif // C4_UTF_HPP_


// (end https://github.com/biojppm/c4core/src/c4/utf.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/format.hpp
// https://github.com/biojppm/c4core/src/c4/format.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_FORMAT_HPP_
#define _C4_FORMAT_HPP_

/** @file format.hpp provides type-safe facilities for formatting arguments
 * to string buffers */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/charconv.hpp
//#include "c4/charconv.hpp"
#if !defined(C4_CHARCONV_HPP_) && !defined(_C4_CHARCONV_HPP_)
#error "amalgamate: file c4/charconv.hpp must have been included at this point"
#endif /* C4_CHARCONV_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/blob.hpp
//#include "c4/blob.hpp"
#if !defined(C4_BLOB_HPP_) && !defined(_C4_BLOB_HPP_)
#error "amalgamate: file c4/blob.hpp must have been included at this point"
#endif /* C4_BLOB_HPP_ */



#ifdef _MSC_VER
#   pragma warning(push)
#   if C4_MSVC_VERSION != C4_MSVC_VERSION_2017
#       pragma warning(disable: 4800) // forcing value to bool 'true' or 'false' (performance warning)
#   endif
#   pragma warning(disable: 4996) // snprintf/scanf: this function or variable may be unsafe
#elif defined(__clang__)
#   pragma clang diagnostic push
#elif defined(__GNUC__)
#   pragma GCC diagnostic push
#   pragma GCC diagnostic ignored "-Wuseless-cast"
#endif

namespace c4 {


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
// formatting truthy types as booleans

namespace fmt {

/** write a variable as an alphabetic boolean, ie as either true or false
 * @param strict_read */
template<class T>
struct boolalpha_
{
    boolalpha_(T val_, bool strict_read_=false) : val(val_ ? true : false), strict_read(strict_read_) {}
    bool val;
    bool strict_read;
};

template<class T>
boolalpha_<T> boolalpha(T const& val, bool strict_read=false)
{
    return boolalpha_<T>(val, strict_read);
}

} // namespace fmt

/** write a variable as an alphabetic boolean, ie as either true or false */
template<class T>
inline size_t to_chars(substr buf, fmt::boolalpha_<T> fmt)
{
    return to_chars(buf, fmt.val ? "true" : "false");
}



//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
// formatting integral types

namespace fmt {

/** format an integral type with a custom radix */
template<typename T>
struct integral_
{
    T val;
    T radix;
    C4_ALWAYS_INLINE integral_(T val_, T radix_) : val(val_), radix(radix_) {}
};

/** format an integral type with a custom radix, and pad with zeroes on the left */
template<typename T>
struct integral_padded_
{
    T val;
    T radix;
    size_t num_digits;
    C4_ALWAYS_INLINE integral_padded_(T val_, T radix_, size_t nd) : val(val_), radix(radix_), num_digits(nd) {}
};

/** format an integral type with a custom radix */
template<class T>
C4_ALWAYS_INLINE integral_<T> integral(T val, T radix=10)
{
    return integral_<T>(val, radix);
}
/** format an integral type with a custom radix */
template<class T>
C4_ALWAYS_INLINE integral_<intptr_t> integral(T const* val, T radix=10)
{
    return integral_<intptr_t>(reinterpret_cast<intptr_t>(val), static_cast<intptr_t>(radix));
}
/** format an integral type with a custom radix */
template<class T>
C4_ALWAYS_INLINE integral_<intptr_t> integral(std::nullptr_t, T radix=10)
{
    return integral_<intptr_t>(intptr_t(0), static_cast<intptr_t>(radix));
}
/** pad the argument with zeroes on the left, with decimal radix */
template<class T>
C4_ALWAYS_INLINE integral_padded_<T> zpad(T val, size_t num_digits)
{
    return integral_padded_<T>(val, T(10), num_digits);
}
/** pad the argument with zeroes on the left */
template<class T>
C4_ALWAYS_INLINE integral_padded_<T> zpad(integral_<T> val, size_t num_digits)
{
    return integral_padded_<T>(val.val, val.radix, num_digits);
}
/** pad the argument with zeroes on the left */
C4_ALWAYS_INLINE integral_padded_<intptr_t> zpad(std::nullptr_t, size_t num_digits)
{
    return integral_padded_<intptr_t>(0, 16, num_digits);
}
/** pad the argument with zeroes on the left */
template<class T>
C4_ALWAYS_INLINE integral_padded_<intptr_t> zpad(T const* val, size_t num_digits)
{
    return integral_padded_<intptr_t>(reinterpret_cast<intptr_t>(val), 16, num_digits);
}
template<class T>
C4_ALWAYS_INLINE integral_padded_<intptr_t> zpad(T * val, size_t num_digits)
{
    return integral_padded_<intptr_t>(reinterpret_cast<intptr_t>(val), 16, num_digits);
}


/** format the pointer as an hexadecimal value */
template<class T>
inline integral_<intptr_t> hex(T * v)
{
    return integral_<intptr_t>(reinterpret_cast<intptr_t>(v), intptr_t(16));
}
/** format the pointer as an hexadecimal value */
template<class T>
inline integral_<intptr_t> hex(T const* v)
{
    return integral_<intptr_t>(reinterpret_cast<intptr_t>(v), intptr_t(16));
}
/** format null as an hexadecimal value
 * @overload hex */
inline integral_<intptr_t> hex(std::nullptr_t)
{
    return integral_<intptr_t>(0, intptr_t(16));
}
/** format the integral_ argument as an hexadecimal value
 * @overload hex */
template<class T>
inline integral_<T> hex(T v)
{
    return integral_<T>(v, T(16));
}

/** format the pointer as an octal value */
template<class T>
inline integral_<intptr_t> oct(T const* v)
{
    return integral_<intptr_t>(reinterpret_cast<intptr_t>(v), intptr_t(8));
}
/** format the pointer as an octal value */
template<class T>
inline integral_<intptr_t> oct(T * v)
{
    return integral_<intptr_t>(reinterpret_cast<intptr_t>(v), intptr_t(8));
}
/** format null as an octal value */
inline integral_<intptr_t> oct(std::nullptr_t)
{
    return integral_<intptr_t>(intptr_t(0), intptr_t(8));
}
/** format the integral_ argument as an octal value */
template<class T>
inline integral_<T> oct(T v)
{
    return integral_<T>(v, T(8));
}

/** format the pointer as a binary 0-1 value
 * @see c4::raw() if you want to use a binary memcpy instead of 0-1 formatting */
template<class T>
inline integral_<intptr_t> bin(T const* v)
{
    return integral_<intptr_t>(reinterpret_cast<intptr_t>(v), intptr_t(2));
}
/** format the pointer as a binary 0-1 value
 * @see c4::raw() if you want to use a binary memcpy instead of 0-1 formatting */
template<class T>
inline integral_<intptr_t> bin(T * v)
{
    return integral_<intptr_t>(reinterpret_cast<intptr_t>(v), intptr_t(2));
}
/** format null as a binary 0-1 value
 * @see c4::raw() if you want to use a binary memcpy instead of 0-1 formatting */
inline integral_<intptr_t> bin(std::nullptr_t)
{
    return integral_<intptr_t>(intptr_t(0), intptr_t(2));
}
/** format the integral_ argument as a binary 0-1 value
 * @see c4::raw() if you want to use a raw memcpy-based binary dump instead of 0-1 formatting */
template<class T>
inline integral_<T> bin(T v)
{
    return integral_<T>(v, T(2));
}


template<class T>
struct overflow_checked_
{
    static_assert(std::is_integral<T>::value, "range checking only for integral types");
    C4_ALWAYS_INLINE overflow_checked_(T &val_) : val(&val_) {}
    T *val;
};
template<class T>
C4_ALWAYS_INLINE overflow_checked_<T> overflow_checked(T &val)
{
   return overflow_checked_<T>(val);
}

} // namespace fmt

/** format an integral_ signed type */
template<typename T>
C4_ALWAYS_INLINE
typename std::enable_if<std::is_signed<T>::value, size_t>::type
to_chars(substr buf, fmt::integral_<T> fmt)
{
    return itoa(buf, fmt.val, fmt.radix);
}
/** format an integral_ signed type, pad with zeroes */
template<typename T>
C4_ALWAYS_INLINE
typename std::enable_if<std::is_signed<T>::value, size_t>::type
to_chars(substr buf, fmt::integral_padded_<T> fmt)
{
    return itoa(buf, fmt.val, fmt.radix, fmt.num_digits);
}

/** format an integral_ unsigned type */
template<typename T>
C4_ALWAYS_INLINE
typename std::enable_if<std::is_unsigned<T>::value, size_t>::type
to_chars(substr buf, fmt::integral_<T> fmt)
{
    return utoa(buf, fmt.val, fmt.radix);
}
/** format an integral_ unsigned type, pad with zeroes */
template<typename T>
C4_ALWAYS_INLINE
typename std::enable_if<std::is_unsigned<T>::value, size_t>::type
to_chars(substr buf, fmt::integral_padded_<T> fmt)
{
    return utoa(buf, fmt.val, fmt.radix, fmt.num_digits);
}

template<class T>
C4_ALWAYS_INLINE bool from_chars(csubstr s, fmt::overflow_checked_<T> wrapper)
{
    if(C4_LIKELY(!overflows<T>(s)))
        return atox(s, wrapper.val);
    return false;
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
// formatting real types

namespace fmt {

template<class T>
struct real_
{
    T val;
    int precision;
    RealFormat_e fmt;
    real_(T v, int prec=-1, RealFormat_e f=FTOA_FLOAT) : val(v), precision(prec), fmt(f)  {}
};

template<class T>
real_<T> real(T val, int precision, RealFormat_e fmt=FTOA_FLOAT)
{
    return real_<T>(val, precision, fmt);
}

} // namespace fmt

inline size_t to_chars(substr buf, fmt::real_< float> fmt) { return ftoa(buf, fmt.val, fmt.precision, fmt.fmt); }
inline size_t to_chars(substr buf, fmt::real_<double> fmt) { return dtoa(buf, fmt.val, fmt.precision, fmt.fmt); }


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
// writing raw binary data

namespace fmt {

/** @see blob_ */
template<class T>
struct raw_wrapper_ : public blob_<T>
{
    size_t alignment;

    C4_ALWAYS_INLINE raw_wrapper_(blob_<T> data, size_t alignment_) noexcept
        :
        blob_<T>(data),
        alignment(alignment_)
    {
        C4_ASSERT_MSG(alignment > 0 && (alignment & (alignment - 1)) == 0, "alignment must be a power of two");
    }
};

using const_raw_wrapper = raw_wrapper_<cbyte>;
using raw_wrapper = raw_wrapper_<byte>;

/** mark a variable to be written in raw binary format, using memcpy
 * @see blob_ */
inline const_raw_wrapper craw(cblob data, size_t alignment=alignof(max_align_t))
{
    return const_raw_wrapper(data, alignment);
}
/** mark a variable to be written in raw binary format, using memcpy
 * @see blob_ */
inline const_raw_wrapper raw(cblob data, size_t alignment=alignof(max_align_t))
{
    return const_raw_wrapper(data, alignment);
}
/** mark a variable to be written in raw binary format, using memcpy
 * @see blob_ */
template<class T>
inline const_raw_wrapper craw(T const& C4_RESTRICT data, size_t alignment=alignof(T))
{
    return const_raw_wrapper(cblob(data), alignment);
}
/** mark a variable to be written in raw binary format, using memcpy
 * @see blob_ */
template<class T>
inline const_raw_wrapper raw(T const& C4_RESTRICT data, size_t alignment=alignof(T))
{
    return const_raw_wrapper(cblob(data), alignment);
}

/** mark a variable to be read in raw binary format, using memcpy */
inline raw_wrapper raw(blob data, size_t alignment=alignof(max_align_t))
{
    return raw_wrapper(data, alignment);
}
/** mark a variable to be read in raw binary format, using memcpy */
template<class T>
inline raw_wrapper raw(T & C4_RESTRICT data, size_t alignment=alignof(T))
{
    return raw_wrapper(blob(data), alignment);
}

} // namespace fmt


/** write a variable in raw binary format, using memcpy */
C4CORE_EXPORT size_t to_chars(substr buf, fmt::const_raw_wrapper r);

/** read a variable in raw binary format, using memcpy */
C4CORE_EXPORT bool from_chars(csubstr buf, fmt::raw_wrapper *r);
/** read a variable in raw binary format, using memcpy */
inline bool from_chars(csubstr buf, fmt::raw_wrapper r)
{
    return from_chars(buf, &r);
}

/** read a variable in raw binary format, using memcpy */
inline size_t from_chars_first(csubstr buf, fmt::raw_wrapper *r)
{
    return from_chars(buf, r);
}
/** read a variable in raw binary format, using memcpy */
inline size_t from_chars_first(csubstr buf, fmt::raw_wrapper r)
{
    return from_chars(buf, &r);
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
// formatting aligned to left/right

namespace fmt {

template<class T>
struct left_
{
    T val;
    size_t width;
    char pad;
    left_(T v, size_t w, char p) : val(v), width(w), pad(p) {}
};

template<class T>
struct right_
{
    T val;
    size_t width;
    char pad;
    right_(T v, size_t w, char p) : val(v), width(w), pad(p) {}
};

/** mark an argument to be aligned left */
template<class T>
left_<T> left(T val, size_t width, char padchar=' ')
{
    return left_<T>(val, width, padchar);
}

/** mark an argument to be aligned right */
template<class T>
right_<T> right(T val, size_t width, char padchar=' ')
{
    return right_<T>(val, width, padchar);
}

} // namespace fmt


template<class T>
size_t to_chars(substr buf, fmt::left_<T> const& C4_RESTRICT align)
{
    size_t ret = to_chars(buf, align.val);
    if(ret >= buf.len || ret >= align.width)
        return ret > align.width ? ret : align.width;
    buf.first(align.width).sub(ret).fill(align.pad);
    to_chars(buf, align.val);
    return align.width;
}

template<class T>
size_t to_chars(substr buf, fmt::right_<T> const& C4_RESTRICT align)
{
    size_t ret = to_chars(buf, align.val);
    if(ret >= buf.len || ret >= align.width)
        return ret > align.width ? ret : align.width;
    size_t rem = static_cast<size_t>(align.width - ret);
    buf.first(rem).fill(align.pad);
    to_chars(buf.sub(rem), align.val);
    return align.width;
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/// @cond dev
// terminates the variadic recursion
inline size_t cat(substr /*buf*/)
{
    return 0;
}
/// @endcond


/** serialize the arguments, concatenating them to the given fixed-size buffer.
 * The buffer size is strictly respected: no writes will occur beyond its end.
 * @return the number of characters needed to write all the arguments into the buffer.
 * @see c4::catrs() if instead of a fixed-size buffer, a resizeable container is desired
 * @see c4::uncat() for the inverse function
 * @see c4::catsep() if a separator between each argument is to be used
 * @see c4::format() if a format string is desired */
template<class Arg, class... Args>
size_t cat(substr buf, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    size_t num = to_chars(buf, a);
    buf  = buf.len >= num ? buf.sub(num) : substr{};
    num += cat(buf, more...);
    return num;
}

/** like c4::cat() but return a substr instead of a size */
template<class... Args>
substr cat_sub(substr buf, Args && ...args)
{
    size_t sz = cat(buf, std::forward<Args>(args)...);
    C4_CHECK(sz <= buf.len);
    return {buf.str, sz <= buf.len ? sz : buf.len};
}


//-----------------------------------------------------------------------------

/// @cond dev
// terminates the variadic recursion
inline size_t uncat(csubstr /*buf*/)
{
    return 0;
}
/// @endcond


/** deserialize the arguments from the given buffer.
 *
 * @return the number of characters read from the buffer, or csubstr::npos
 *   if a conversion was not successful.
 * @see c4::cat(). c4::uncat() is the inverse of c4::cat(). */
template<class Arg, class... Args>
size_t uncat(csubstr buf, Arg & C4_RESTRICT a, Args & C4_RESTRICT ...more)
{
    size_t out = from_chars_first(buf, &a);
    if(C4_UNLIKELY(out == csubstr::npos))
        return csubstr::npos;
    buf  = buf.len >= out ? buf.sub(out) : substr{};
    size_t num = uncat(buf, more...);
    if(C4_UNLIKELY(num == csubstr::npos))
        return csubstr::npos;
    return out + num;
}



//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

namespace detail {

template<class Sep>
inline size_t catsep_more(substr /*buf*/, Sep const& C4_RESTRICT /*sep*/)
{
    return 0;
}

template<class Sep, class Arg, class... Args>
size_t catsep_more(substr buf, Sep const& C4_RESTRICT sep, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    size_t ret = to_chars(buf, sep), num = ret;
    buf  = buf.len >= ret ? buf.sub(ret) : substr{};
    ret  = to_chars(buf, a);
    num += ret;
    buf  = buf.len >= ret ? buf.sub(ret) : substr{};
    ret  = catsep_more(buf, sep, more...);
    num += ret;
    return num;
}

template<class Sep>
inline size_t uncatsep_more(csubstr /*buf*/, Sep & /*sep*/)
{
    return 0;
}

template<class Sep, class Arg, class... Args>
size_t uncatsep_more(csubstr buf, Sep & C4_RESTRICT sep, Arg & C4_RESTRICT a, Args & C4_RESTRICT ...more)
{
    size_t ret = from_chars_first(buf, &sep), num = ret;
    if(C4_UNLIKELY(ret == csubstr::npos))
        return csubstr::npos;
    buf  = buf.len >= ret ? buf.sub(ret) : substr{};
    ret  = from_chars_first(buf, &a);
    if(C4_UNLIKELY(ret == csubstr::npos))
        return csubstr::npos;
    num += ret;
    buf  = buf.len >= ret ? buf.sub(ret) : substr{};
    ret  = uncatsep_more(buf, sep, more...);
    if(C4_UNLIKELY(ret == csubstr::npos))
        return csubstr::npos;
    num += ret;
    return num;
}

} // namespace detail


/** serialize the arguments, concatenating them to the given fixed-size
 * buffer, using a separator between each argument.
 * The buffer size is strictly respected: no writes will occur beyond its end.
 * @return the number of characters needed to write all the arguments into the buffer.
 * @see c4::catseprs() if instead of a fixed-size buffer, a resizeable container is desired
 * @see c4::uncatsep() for the inverse function (ie, reading instead of writing)
 * @see c4::cat() if no separator is needed
 * @see c4::format() if a format string is desired */
template<class Sep, class Arg, class... Args>
size_t catsep(substr buf, Sep const& C4_RESTRICT sep, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    size_t num = to_chars(buf, a);
    buf  = buf.len >= num ? buf.sub(num) : substr{};
    num += detail::catsep_more(buf, sep, more...);
    return num;
}

/** like c4::catsep() but return a substr instead of a size
 * @see c4::catsep(). c4::uncatsep() is the inverse of c4::catsep(). */
template<class... Args>
substr catsep_sub(substr buf, Args && ...args)
{
    size_t sz = catsep(buf, std::forward<Args>(args)...);
    C4_CHECK(sz <= buf.len);
    return {buf.str, sz <= buf.len ? sz : buf.len};
}

/** deserialize the arguments from the given buffer, using a separator.
 *
 * @return the number of characters read from the buffer, or csubstr::npos
 *   if a conversion was not successful
 * @see c4::catsep(). c4::uncatsep() is the inverse of c4::catsep(). */
template<class Sep, class Arg, class... Args>
size_t uncatsep(csubstr buf, Sep & C4_RESTRICT sep, Arg & C4_RESTRICT a, Args & C4_RESTRICT ...more)
{
    size_t ret = from_chars_first(buf, &a), num = ret;
    if(C4_UNLIKELY(ret == csubstr::npos))
        return csubstr::npos;
    buf  = buf.len >= ret ? buf.sub(ret) : substr{};
    ret  = detail::uncatsep_more(buf, sep, more...);
    if(C4_UNLIKELY(ret == csubstr::npos))
        return csubstr::npos;
    num += ret;
    return num;
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/// @cond dev
// terminates the variadic recursion
inline size_t format(substr buf, csubstr fmt)
{
    return to_chars(buf, fmt);
}
/// @endcond


/** using a format string, serialize the arguments into the given
 * fixed-size buffer.
 * The buffer size is strictly respected: no writes will occur beyond its end.
 * In the format string, each argument is marked with a compact
 * curly-bracket pair: {}. Arguments beyond the last curly bracket pair
 * are silently ignored. For example:
 * @code{.cpp}
 * c4::format(buf, "the {} drank {} {}", "partier", 5, "beers"); // the partier drank 5 beers
 * c4::format(buf, "the {} drank {} {}", "programmer", 6, "coffees"); // the programmer drank 6 coffees
 * @endcode
 * @return the number of characters needed to write into the buffer.
 * @see c4::formatrs() if instead of a fixed-size buffer, a resizeable container is desired
 * @see c4::unformat() for the inverse function
 * @see c4::cat() if no format or separator is needed
 * @see c4::catsep() if no format is needed, but a separator must be used */
template<class Arg, class... Args>
size_t format(substr buf, csubstr fmt, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    size_t pos = fmt.find("{}"); // @todo use _find_fmt()
    if(C4_UNLIKELY(pos == csubstr::npos))
        return to_chars(buf, fmt);
    size_t num = to_chars(buf, fmt.sub(0, pos));
    size_t out = num;
    buf  = buf.len >= num ? buf.sub(num) : substr{};
    num  = to_chars(buf, a);
    out += num;
    buf  = buf.len >= num ? buf.sub(num) : substr{};
    num  = format(buf, fmt.sub(pos + 2), more...);
    out += num;
    return out;
}

/** like c4::format() but return a substr instead of a size
 * @see c4::format()
 * @see c4::catsep(). uncatsep() is the inverse of catsep(). */
template<class... Args>
substr format_sub(substr buf, csubstr fmt, Args const& C4_RESTRICT ...args)
{
    size_t sz = c4::format(buf, fmt, args...);
    C4_CHECK(sz <= buf.len);
    return {buf.str, sz <= buf.len ? sz : buf.len};
}


//-----------------------------------------------------------------------------

/// @cond dev
// terminates the variadic recursion
inline size_t unformat(csubstr /*buf*/, csubstr fmt)
{
    return fmt.len;
}
/// @endcond


/** using a format string, deserialize the arguments from the given
 * buffer.
 * @return the number of characters read from the buffer, or npos if a conversion failed.
 * @see c4::format(). c4::unformat() is the inverse function to format(). */
template<class Arg, class... Args>
size_t unformat(csubstr buf, csubstr fmt, Arg & C4_RESTRICT a, Args & C4_RESTRICT ...more)
{
    const size_t pos = fmt.find("{}");
    if(C4_UNLIKELY(pos == csubstr::npos))
        return unformat(buf, fmt);
    size_t num = pos;
    size_t out = num;
    buf  = buf.len >= num ? buf.sub(num) : substr{};
    num  = from_chars_first(buf, &a);
    if(C4_UNLIKELY(num == csubstr::npos))
        return csubstr::npos;
    out += num;
    buf  = buf.len >= num ? buf.sub(num) : substr{};
    num  = unformat(buf, fmt.sub(pos + 2), more...);
    if(C4_UNLIKELY(num == csubstr::npos))
        return csubstr::npos;
    out += num;
    return out;
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** a tag type for marking append to container
 * @see c4::catrs() */
struct append_t {};

/** a tag variable
 * @see c4::catrs() */
constexpr const append_t append = {};


//-----------------------------------------------------------------------------

/** like c4::cat(), but receives a container, and resizes it as needed to contain
 * the result. The container is overwritten. To append to it, use the append
 * overload.
 * @see c4::cat() */
template<class CharOwningContainer, class... Args>
inline void catrs(CharOwningContainer * C4_RESTRICT cont, Args const& C4_RESTRICT ...args)
{
retry:
    substr buf = to_substr(*cont);
    size_t ret = cat(buf, args...);
    cont->resize(ret);
    if(ret > buf.len)
        goto retry;
}

/** like c4::cat(), but creates and returns a new container sized as needed to contain
 * the result.
 * @see c4::cat() */
template<class CharOwningContainer, class... Args>
inline CharOwningContainer catrs(Args const& C4_RESTRICT ...args)
{
    CharOwningContainer cont;
    catrs(&cont, args...);
    return cont;
}

/** like c4::cat(), but receives a container, and appends to it instead of
 * overwriting it. The container is resized as needed to contain the result.
 * @return the region newly appended to the original container
 * @see c4::cat()
 * @see c4::catrs() */
template<class CharOwningContainer, class... Args>
inline csubstr catrs(append_t, CharOwningContainer * C4_RESTRICT cont, Args const& C4_RESTRICT ...args)
{
    const size_t pos = cont->size();
retry:
    substr buf = to_substr(*cont).sub(pos);
    size_t ret = cat(buf, args...);
    cont->resize(pos + ret);
    if(ret > buf.len)
        goto retry;
    return to_csubstr(*cont).range(pos, cont->size());
}


//-----------------------------------------------------------------------------

/// @cond dev
// terminates the recursion
template<class CharOwningContainer, class Sep, class... Args>
inline void catseprs(CharOwningContainer * C4_RESTRICT, Sep const& C4_RESTRICT)
{
    return;
}
/// @end cond


/** like c4::catsep(), but receives a container, and resizes it as needed to contain the result.
 * The container is overwritten. To append to the container use the append overload.
 * @see c4::catsep() */
template<class CharOwningContainer, class Sep, class... Args>
inline void catseprs(CharOwningContainer * C4_RESTRICT cont, Sep const& C4_RESTRICT sep, Args const& C4_RESTRICT ...args)
{
retry:
    substr buf = to_substr(*cont);
    size_t ret = catsep(buf, sep, args...);
    cont->resize(ret);
    if(ret > buf.len)
        goto retry;
}

/** like c4::catsep(), but create a new container with the result.
 * @return the requested container */
template<class CharOwningContainer, class Sep, class... Args>
inline CharOwningContainer catseprs(Sep const& C4_RESTRICT sep, Args const& C4_RESTRICT ...args)
{
    CharOwningContainer cont;
    catseprs(&cont, sep, args...);
    return cont;
}


/// @cond dev
// terminates the recursion
template<class CharOwningContainer, class Sep, class... Args>
inline csubstr catseprs(append_t, CharOwningContainer * C4_RESTRICT, Sep const& C4_RESTRICT)
{
    csubstr s;
    return s;
}
/// @endcond

/** like catsep(), but receives a container, and appends the arguments, resizing the
 * container as needed to contain the result. The buffer is appended to.
 * @return a csubstr of the appended part
 * @ingroup formatting_functions */
template<class CharOwningContainer, class Sep, class... Args>
inline csubstr catseprs(append_t, CharOwningContainer * C4_RESTRICT cont, Sep const& C4_RESTRICT sep, Args const& C4_RESTRICT ...args)
{
    const size_t pos = cont->size();
retry:
    substr buf = to_substr(*cont).sub(pos);
    size_t ret = catsep(buf, sep, args...);
    cont->resize(pos + ret);
    if(ret > buf.len)
        goto retry;
    return to_csubstr(*cont).range(pos, cont->size());
}


//-----------------------------------------------------------------------------

/** like c4::format(), but receives a container, and resizes it as needed
 * to contain the result.  The container is overwritten. To append to
 * the container use the append overload.
 * @see c4::format() */
template<class CharOwningContainer, class... Args>
inline void formatrs(CharOwningContainer * C4_RESTRICT cont, csubstr fmt, Args const& C4_RESTRICT ...args)
{
retry:
    substr buf = to_substr(*cont);
    size_t ret = format(buf, fmt, args...);
    cont->resize(ret);
    if(ret > buf.len)
        goto retry;
}

/** like c4::format(), but create a new container with the result.
 * @return the requested container */
template<class CharOwningContainer, class... Args>
inline CharOwningContainer formatrs(csubstr fmt, Args const& C4_RESTRICT ...args)
{
    CharOwningContainer cont;
    formatrs(&cont, fmt, args...);
    return cont;
}

/** like format(), but receives a container, and appends the
 * arguments, resizing the container as needed to contain the
 * result. The buffer is appended to.
 * @return the region newly appended to the original container
 * @ingroup formatting_functions */
template<class CharOwningContainer, class... Args>
inline csubstr formatrs(append_t, CharOwningContainer * C4_RESTRICT cont, csubstr fmt, Args const& C4_RESTRICT ...args)
{
    const size_t pos = cont->size();
retry:
    substr buf = to_substr(*cont).sub(pos);
    size_t ret = format(buf, fmt, args...);
    cont->resize(pos + ret);
    if(ret > buf.len)
        goto retry;
    return to_csubstr(*cont).range(pos, cont->size());
}

} // namespace c4

#ifdef _MSC_VER
#   pragma warning(pop)
#elif defined(__clang__)
#   pragma clang diagnostic pop
#elif defined(__GNUC__)
#   pragma GCC diagnostic pop
#endif

#endif /* _C4_FORMAT_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/format.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/dump.hpp
// https://github.com/biojppm/c4core/src/c4/dump.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef C4_DUMP_HPP_
#define C4_DUMP_HPP_

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/substr.hpp
//#include <c4/substr.hpp>
#if !defined(C4_SUBSTR_HPP_) && !defined(_C4_SUBSTR_HPP_)
#error "amalgamate: file c4/substr.hpp must have been included at this point"
#endif /* C4_SUBSTR_HPP_ */


namespace c4 {


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
/** type of the function to dump characters */
using DumperPfn = void (*)(csubstr buf);


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

template<DumperPfn dumpfn, class Arg>
inline size_t dump(substr buf, Arg const& a)
{
    size_t sz = to_chars(buf, a); // need to serialize to the buffer
    if(C4_LIKELY(sz <= buf.len))
        dumpfn(buf.first(sz));
    return sz;
}

template<class DumperFn, class Arg>
inline size_t dump(DumperFn &&dumpfn, substr buf, Arg const& a)
{
    size_t sz = to_chars(buf, a); // need to serialize to the buffer
    if(C4_LIKELY(sz <= buf.len))
        dumpfn(buf.first(sz));
    return sz;
}

template<DumperPfn dumpfn>
inline size_t dump(substr buf, csubstr a)
{
    if(buf.len)
        dumpfn(a); // dump directly, no need to serialize to the buffer
    return 0; // no space was used in the buffer
}

template<class DumperFn>
inline size_t dump(DumperFn &&dumpfn, substr buf, csubstr a)
{
    if(buf.len)
        dumpfn(a); // dump directly, no need to serialize to the buffer
    return 0; // no space was used in the buffer
}

template<DumperPfn dumpfn, size_t N>
inline size_t dump(substr buf, const char (&a)[N])
{
    if(buf.len)
        dumpfn(csubstr(a)); // dump directly, no need to serialize to the buffer
    return 0; // no space was used in the buffer
}

template<class DumperFn, size_t N>
inline size_t dump(DumperFn &&dumpfn, substr buf, const char (&a)[N])
{
    if(buf.len)
        dumpfn(csubstr(a)); // dump directly, no need to serialize to the buffer
    return 0; // no space was used in the buffer
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** */
struct DumpResults
{
    enum : size_t { noarg = (size_t)-1 };
    size_t bufsize = 0;
    size_t lastok = noarg;
    bool success_until(size_t expected) const { return lastok == noarg ? false : lastok >= expected; }
    bool write_arg(size_t arg) const { return lastok == noarg || arg > lastok; }
    size_t argfail() const { return lastok + 1; }
};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/// @cond dev
// terminates the variadic recursion
template<class DumperFn>
size_t cat_dump(DumperFn &&, substr)
{
    return 0;
}

// terminates the variadic recursion
template<DumperPfn dumpfn>
size_t cat_dump(substr)
{
    return 0;
}
/// @endcond

/** take the function pointer as a function argument */
template<class DumperFn, class Arg, class... Args>
size_t cat_dump(DumperFn &&dumpfn, substr buf, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    size_t size_for_a = dump(dumpfn, buf, a);
    if(C4_UNLIKELY(size_for_a > buf.len))
        buf = buf.first(0); // ensure no more calls
    size_t size_for_more = cat_dump(dumpfn, buf, more...);
    return size_for_more > size_for_a ? size_for_more : size_for_a;
}

/** take the function pointer as a template argument */
template<DumperPfn dumpfn,class Arg, class... Args>
size_t cat_dump(substr buf, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    size_t size_for_a = dump<dumpfn>(buf, a);
    if(C4_LIKELY(size_for_a > buf.len))
        buf = buf.first(0); // ensure no more calls
    size_t size_for_more = cat_dump<dumpfn>(buf, more...);
    return size_for_more > size_for_a ? size_for_more : size_for_a;
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/// @cond dev
namespace detail {

// terminates the variadic recursion
template<DumperPfn dumpfn, class Arg>
DumpResults cat_dump_resume(size_t currarg, DumpResults results, substr buf, Arg const& C4_RESTRICT a)
{
    if(C4_LIKELY(results.write_arg(currarg)))
    {
        size_t sz = dump<dumpfn>(buf, a);  // yield to the specialized function
        if(currarg == results.lastok + 1 && sz <= buf.len)
            results.lastok = currarg;
        results.bufsize = sz > results.bufsize ? sz : results.bufsize;
    }
    return results;
}

// terminates the variadic recursion
template<class DumperFn, class Arg>
DumpResults cat_dump_resume(size_t currarg, DumperFn &&dumpfn, DumpResults results, substr buf, Arg const& C4_RESTRICT a)
{
    if(C4_LIKELY(results.write_arg(currarg)))
    {
        size_t sz = dump(dumpfn, buf, a);  // yield to the specialized function
        if(currarg == results.lastok + 1 && sz <= buf.len)
            results.lastok = currarg;
        results.bufsize = sz > results.bufsize ? sz : results.bufsize;
    }
    return results;
}

template<DumperPfn dumpfn, class Arg, class... Args>
DumpResults cat_dump_resume(size_t currarg, DumpResults results, substr buf, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    results = detail::cat_dump_resume<dumpfn>(currarg, results, buf, a);
    return detail::cat_dump_resume<dumpfn>(currarg + 1u, results, buf, more...);
}

template<class DumperFn, class Arg, class... Args>
DumpResults cat_dump_resume(size_t currarg, DumperFn &&dumpfn, DumpResults results, substr buf, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    results = detail::cat_dump_resume(currarg, dumpfn, results, buf, a);
    return detail::cat_dump_resume(currarg + 1u, dumpfn, results, buf, more...);
}
} // namespace detail
/// @endcond


template<DumperPfn dumpfn, class Arg, class... Args>
C4_ALWAYS_INLINE DumpResults cat_dump_resume(DumpResults results, substr buf, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    if(results.bufsize > buf.len)
        return results;
    return detail::cat_dump_resume<dumpfn>(0u, results, buf, a, more...);
}

template<class DumperFn, class Arg, class... Args>
C4_ALWAYS_INLINE DumpResults cat_dump_resume(DumperFn &&dumpfn, DumpResults results, substr buf, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    if(results.bufsize > buf.len)
        return results;
    return detail::cat_dump_resume(0u, dumpfn, results, buf, a, more...);
}

template<DumperPfn dumpfn, class Arg, class... Args>
C4_ALWAYS_INLINE DumpResults cat_dump_resume(substr buf, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    return detail::cat_dump_resume<dumpfn>(0u, DumpResults{}, buf, a, more...);
}

template<class DumperFn, class Arg, class... Args>
C4_ALWAYS_INLINE DumpResults cat_dump_resume(DumperFn &&dumpfn, substr buf, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    return detail::cat_dump_resume(0u, dumpfn, DumpResults{}, buf, a, more...);
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/// @cond dev
// terminate the recursion
template<class DumperFn, class Sep>
size_t catsep_dump(DumperFn &&, substr, Sep const& C4_RESTRICT)
{
    return 0;
}

// terminate the recursion
template<DumperPfn dumpfn, class Sep>
size_t catsep_dump(substr, Sep const& C4_RESTRICT)
{
    return 0;
}
/// @endcond

/** take the function pointer as a function argument */
template<class DumperFn, class Sep, class Arg, class... Args>
size_t catsep_dump(DumperFn &&dumpfn, substr buf, Sep const& C4_RESTRICT sep, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    size_t sz = dump(dumpfn, buf, a);
    if(C4_UNLIKELY(sz > buf.len))
        buf = buf.first(0); // ensure no more calls
    if C4_IF_CONSTEXPR (sizeof...(more) > 0)
    {
        size_t szsep = dump(dumpfn, buf, sep);
        if(C4_UNLIKELY(szsep > buf.len))
            buf = buf.first(0); // ensure no more calls
        sz = sz > szsep ? sz : szsep;
    }
    size_t size_for_more = catsep_dump(dumpfn, buf, sep, more...);
    return size_for_more > sz ? size_for_more : sz;
}

/** take the function pointer as a template argument */
template<DumperPfn dumpfn, class Sep, class Arg, class... Args>
size_t catsep_dump(substr buf, Sep const& C4_RESTRICT sep, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    size_t sz = dump<dumpfn>(buf, a);
    if(C4_UNLIKELY(sz > buf.len))
        buf = buf.first(0); // ensure no more calls
    if C4_IF_CONSTEXPR (sizeof...(more) > 0)
    {
        size_t szsep = dump<dumpfn>(buf, sep);
        if(C4_UNLIKELY(szsep > buf.len))
            buf = buf.first(0); // ensure no more calls
        sz = sz > szsep ? sz : szsep;
    }
    size_t size_for_more = catsep_dump<dumpfn>(buf, sep, more...);
    return size_for_more > sz ? size_for_more : sz;
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/// @cond dev
namespace detail {
template<DumperPfn dumpfn, class Arg>
void catsep_dump_resume_(size_t currarg, DumpResults *C4_RESTRICT results, substr *C4_RESTRICT buf, Arg const& C4_RESTRICT a)
{
    if(C4_LIKELY(results->write_arg(currarg)))
    {
        size_t sz = dump<dumpfn>(*buf, a);
        results->bufsize = sz > results->bufsize ? sz : results->bufsize;
        if(C4_LIKELY(sz <= buf->len))
            results->lastok = currarg;
        else
            buf->len = 0;
    }
}

template<class DumperFn, class Arg>
void catsep_dump_resume_(size_t currarg, DumperFn &&dumpfn, DumpResults *C4_RESTRICT results, substr *C4_RESTRICT buf, Arg const& C4_RESTRICT a)
{
    if(C4_LIKELY(results->write_arg(currarg)))
    {
        size_t sz = dump(dumpfn, *buf, a);
        results->bufsize = sz > results->bufsize ? sz : results->bufsize;
        if(C4_LIKELY(sz <= buf->len))
            results->lastok = currarg;
        else
            buf->len = 0;
    }
}

template<DumperPfn dumpfn, class Sep, class Arg>
C4_ALWAYS_INLINE void catsep_dump_resume(size_t currarg, DumpResults *C4_RESTRICT results, substr *C4_RESTRICT buf, Sep const& C4_RESTRICT, Arg const& C4_RESTRICT a)
{
    detail::catsep_dump_resume_<dumpfn>(currarg, results, buf, a);
}

template<class DumperFn, class Sep, class Arg>
C4_ALWAYS_INLINE void catsep_dump_resume(size_t currarg, DumperFn &&dumpfn, DumpResults *C4_RESTRICT results, substr *C4_RESTRICT buf, Sep const& C4_RESTRICT, Arg const& C4_RESTRICT a)
{
    detail::catsep_dump_resume_(currarg, dumpfn, results, buf, a);
}

template<DumperPfn dumpfn, class Sep, class Arg, class... Args>
C4_ALWAYS_INLINE void catsep_dump_resume(size_t currarg, DumpResults *C4_RESTRICT results, substr *C4_RESTRICT buf, Sep const& C4_RESTRICT sep, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    detail::catsep_dump_resume_<dumpfn>(currarg     , results, buf, a);
    detail::catsep_dump_resume_<dumpfn>(currarg + 1u, results, buf, sep);
    detail::catsep_dump_resume <dumpfn>(currarg + 2u, results, buf, sep, more...);
}

template<class DumperFn, class Sep, class Arg, class... Args>
C4_ALWAYS_INLINE void catsep_dump_resume(size_t currarg, DumperFn &&dumpfn, DumpResults *C4_RESTRICT results, substr *C4_RESTRICT buf, Sep const& C4_RESTRICT sep, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    detail::catsep_dump_resume_(currarg     , dumpfn, results, buf, a);
    detail::catsep_dump_resume_(currarg + 1u, dumpfn, results, buf, sep);
    detail::catsep_dump_resume (currarg + 2u, dumpfn, results, buf, sep, more...);
}
} // namespace detail
/// @endcond


template<DumperPfn dumpfn, class Sep, class... Args>
C4_ALWAYS_INLINE DumpResults catsep_dump_resume(DumpResults results, substr buf, Sep const& C4_RESTRICT sep, Args const& C4_RESTRICT ...more)
{
    detail::catsep_dump_resume<dumpfn>(0u, &results, &buf, sep, more...);
    return results;
}

template<class DumperFn, class Sep, class... Args>
C4_ALWAYS_INLINE DumpResults catsep_dump_resume(DumperFn &&dumpfn, DumpResults results, substr buf, Sep const& C4_RESTRICT sep, Args const& C4_RESTRICT ...more)
{
    detail::catsep_dump_resume(0u, dumpfn, &results, &buf, sep, more...);
    return results;
}

template<DumperPfn dumpfn, class Sep, class... Args>
C4_ALWAYS_INLINE DumpResults catsep_dump_resume(substr buf, Sep const& C4_RESTRICT sep, Args const& C4_RESTRICT ...more)
{
    DumpResults results;
    detail::catsep_dump_resume<dumpfn>(0u, &results, &buf, sep, more...);
    return results;
}

template<class DumperFn, class Sep, class... Args>
C4_ALWAYS_INLINE DumpResults catsep_dump_resume(DumperFn &&dumpfn, substr buf, Sep const& C4_RESTRICT sep, Args const& C4_RESTRICT ...more)
{
    DumpResults results;
    detail::catsep_dump_resume(0u, dumpfn, &results, &buf, sep, more...);
    return results;
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** take the function pointer as a function argument */
template<class DumperFn>
C4_ALWAYS_INLINE size_t format_dump(DumperFn &&dumpfn, substr buf, csubstr fmt)
{
    // we can dump without using buf
    // but we'll only dump if the buffer is ok
    if(C4_LIKELY(buf.len > 0 && fmt.len))
        dumpfn(fmt);
    return 0u;
}

/** take the function pointer as a function argument */
template<DumperPfn dumpfn>
C4_ALWAYS_INLINE size_t format_dump(substr buf, csubstr fmt)
{
    // we can dump without using buf
    // but we'll only dump if the buffer is ok
    if(C4_LIKELY(buf.len > 0 && fmt.len > 0))
        dumpfn(fmt);
    return 0u;
}

/** take the function pointer as a function argument */
template<class DumperFn, class Arg, class... Args>
size_t format_dump(DumperFn &&dumpfn, substr buf, csubstr fmt, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    // we can dump without using buf
    // but we'll only dump if the buffer is ok
    size_t pos = fmt.find("{}"); // @todo use _find_fmt()
    if(C4_UNLIKELY(pos == csubstr::npos))
    {
        if(C4_LIKELY(buf.len > 0 && fmt.len > 0))
            dumpfn(fmt);
        return 0u;
    }
    if(C4_LIKELY(buf.len > 0 && pos > 0))
        dumpfn(fmt.first(pos)); // we can dump without using buf
    fmt = fmt.sub(pos + 2); // skip {} do this before assigning to pos again
    pos = dump(dumpfn, buf, a);
    if(C4_UNLIKELY(pos > buf.len))
        buf.len = 0; // ensure no more calls to dump
    size_t size_for_more = format_dump(dumpfn, buf, fmt, more...);
    return size_for_more > pos ? size_for_more : pos;
}

/** take the function pointer as a template argument */
template<DumperPfn dumpfn, class Arg, class... Args>
size_t format_dump(substr buf, csubstr fmt, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    // we can dump without using buf
    // but we'll only dump if the buffer is ok
    size_t pos = fmt.find("{}"); // @todo use _find_fmt()
    if(C4_UNLIKELY(pos == csubstr::npos))
    {
        if(C4_LIKELY(buf.len > 0 && fmt.len > 0))
            dumpfn(fmt);
        return 0u;
    }
    if(C4_LIKELY(buf.len > 0 && pos > 0))
        dumpfn(fmt.first(pos)); // we can dump without using buf
    fmt = fmt.sub(pos + 2); // skip {} do this before assigning to pos again
    pos = dump<dumpfn>(buf, a);
    if(C4_UNLIKELY(pos > buf.len))
        buf.len = 0; // ensure no more calls to dump
    size_t size_for_more = format_dump<dumpfn>(buf, fmt, more...);
    return size_for_more > pos ? size_for_more : pos;
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/// @cond dev
namespace detail {

template<DumperPfn dumpfn>
DumpResults format_dump_resume(size_t currarg, DumpResults results, substr buf, csubstr fmt)
{
    // we can dump without using buf
    // but we'll only dump if the buffer is ok
    if(C4_LIKELY(buf.len > 0))
    {
        dumpfn(fmt);
        results.lastok = currarg;
    }
    return results;
}

template<class DumperFn>
DumpResults format_dump_resume(size_t currarg, DumperFn &&dumpfn, DumpResults results, substr buf, csubstr fmt)
{
    // we can dump without using buf
    // but we'll only dump if the buffer is ok
    if(C4_LIKELY(buf.len > 0))
    {
        dumpfn(fmt);
        results.lastok = currarg;
    }
    return results;
}

template<DumperPfn dumpfn, class Arg, class... Args>
DumpResults format_dump_resume(size_t currarg, DumpResults results, substr buf, csubstr fmt, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    // we need to process the format even if we're not
    // going to print the first arguments because we're resuming
    size_t pos = fmt.find("{}"); // @todo use _find_fmt()
    // we can dump without using buf
    // but we'll only dump if the buffer is ok
    if(C4_LIKELY(results.write_arg(currarg)))
    {
        if(C4_UNLIKELY(pos == csubstr::npos))
        {
            if(C4_LIKELY(buf.len > 0))
            {
                results.lastok = currarg;
                dumpfn(fmt);
            }
            return results;
        }
        if(C4_LIKELY(buf.len > 0))
        {
            results.lastok = currarg;
            dumpfn(fmt.first(pos));
        }
    }
    fmt = fmt.sub(pos + 2);
    if(C4_LIKELY(results.write_arg(currarg + 1)))
    {
        pos = dump<dumpfn>(buf, a);
        results.bufsize = pos > results.bufsize ? pos : results.bufsize;
        if(C4_LIKELY(pos <= buf.len))
            results.lastok = currarg + 1;
        else
            buf.len = 0;
    }
    return detail::format_dump_resume<dumpfn>(currarg + 2u, results, buf, fmt, more...);
}
/// @endcond


template<class DumperFn, class Arg, class... Args>
DumpResults format_dump_resume(size_t currarg, DumperFn &&dumpfn, DumpResults results, substr buf, csubstr fmt, Arg const& C4_RESTRICT a, Args const& C4_RESTRICT ...more)
{
    // we need to process the format even if we're not
    // going to print the first arguments because we're resuming
    size_t pos = fmt.find("{}"); // @todo use _find_fmt()
    // we can dump without using buf
    // but we'll only dump if the buffer is ok
    if(C4_LIKELY(results.write_arg(currarg)))
    {
        if(C4_UNLIKELY(pos == csubstr::npos))
        {
            if(C4_LIKELY(buf.len > 0))
            {
                results.lastok = currarg;
                dumpfn(fmt);
            }
            return results;
        }
        if(C4_LIKELY(buf.len > 0))
        {
            results.lastok = currarg;
            dumpfn(fmt.first(pos));
        }
    }
    fmt = fmt.sub(pos + 2);
    if(C4_LIKELY(results.write_arg(currarg + 1)))
    {
        pos = dump(dumpfn, buf, a);
        results.bufsize = pos > results.bufsize ? pos : results.bufsize;
        if(C4_LIKELY(pos <= buf.len))
            results.lastok = currarg + 1;
        else
            buf.len = 0;
    }
    return detail::format_dump_resume(currarg + 2u, dumpfn, results, buf, fmt, more...);
}
} // namespace detail


template<DumperPfn dumpfn, class... Args>
C4_ALWAYS_INLINE DumpResults format_dump_resume(DumpResults results, substr buf, csubstr fmt, Args const& C4_RESTRICT ...more)
{
    return detail::format_dump_resume<dumpfn>(0u, results, buf, fmt, more...);
}

template<class DumperFn, class... Args>
C4_ALWAYS_INLINE DumpResults format_dump_resume(DumperFn &&dumpfn, DumpResults results, substr buf, csubstr fmt, Args const& C4_RESTRICT ...more)
{
    return detail::format_dump_resume(0u, dumpfn, results, buf, fmt, more...);
}


template<DumperPfn dumpfn, class... Args>
C4_ALWAYS_INLINE DumpResults format_dump_resume(substr buf, csubstr fmt, Args const& C4_RESTRICT ...more)
{
    return detail::format_dump_resume<dumpfn>(0u, DumpResults{}, buf, fmt, more...);
}

template<class DumperFn, class... Args>
C4_ALWAYS_INLINE DumpResults format_dump_resume(DumperFn &&dumpfn, substr buf, csubstr fmt, Args const& C4_RESTRICT ...more)
{
    return detail::format_dump_resume(0u, dumpfn, DumpResults{}, buf, fmt, more...);
}


} // namespace c4


#endif /* C4_DUMP_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/dump.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/enum.hpp
// https://github.com/biojppm/c4core/src/c4/enum.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_ENUM_HPP_
#define _C4_ENUM_HPP_

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/error.hpp
//#include "c4/error.hpp"
#if !defined(C4_ERROR_HPP_) && !defined(_C4_ERROR_HPP_)
#error "amalgamate: file c4/error.hpp must have been included at this point"
#endif /* C4_ERROR_HPP_ */

//included above:
//#include <string.h>

/** @file enum.hpp utilities for enums: convert to/from string
 */


namespace c4 {

//! taken from http://stackoverflow.com/questions/15586163/c11-type-trait-to-differentiate-between-enum-class-and-regular-enum
template<typename Enum>
using is_scoped_enum = std::integral_constant<bool, std::is_enum<Enum>::value && !std::is_convertible<Enum, int>::value>;


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

typedef enum {
    EOFFS_NONE = 0,  ///< no offset
    EOFFS_CLS = 1,   ///< get the enum offset for the class name. @see eoffs_cls()
    EOFFS_PFX = 2,   ///< get the enum offset for the enum prefix. @see eoffs_pfx()
    _EOFFS_LAST      ///< reserved
} EnumOffsetType;


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
/** A simple (proxy) container for the value-name pairs of an enum type.
 * Uses linear search for finds; this could be improved for time-critical
 * code. */
template<class Enum>
class EnumSymbols
{
public:

    struct Sym
    {
        Enum value;
        const char *name;

        bool cmp(const char *s) const;
        bool cmp(const char *s, size_t len) const;

        const char *name_offs(EnumOffsetType t) const;
    };

    using const_iterator = Sym const*;

public:

    template<size_t N>
    EnumSymbols(Sym const (&p)[N]) : m_symbols(p), m_num(N) {}

    size_t size() const { return m_num; }
    bool empty() const { return m_num == 0; }

    Sym const* get(Enum v) const { auto p = find(v); C4_CHECK_MSG(p != nullptr, "could not find symbol=%zd", (std::ptrdiff_t)v); return p; }
    Sym const* get(const char *s) const { auto p = find(s); C4_CHECK_MSG(p != nullptr, "could not find symbol \"%s\"", s); return p; }
    Sym const* get(const char *s, size_t len) const { auto p = find(s, len); C4_CHECK_MSG(p != nullptr, "could not find symbol \"%.*s\"", len, s); return p; }

    Sym const* find(Enum v) const;
    Sym const* find(const char *s) const;
    Sym const* find(const char *s, size_t len) const;

    Sym const& operator[] (size_t i) const { C4_CHECK(i < m_num); return m_symbols[i]; }

    Sym const* begin() const { return m_symbols; }
    Sym const* end  () const { return m_symbols + m_num; }

private:

    Sym const* m_symbols;
    size_t const m_num;

};

//-----------------------------------------------------------------------------
/** return an EnumSymbols object for the enum type T
 *
 * @warning SPECIALIZE! This needs to be specialized for each enum
 * type. Failure to provide a specialization will cause a linker
 * error. */
template<class Enum>
EnumSymbols<Enum> const esyms();


/** return the offset for an enum symbol class. For example,
 * eoffs_cls<MyEnumClass>() would be 13=strlen("MyEnumClass::").
 *
 * With this function you can announce that the full prefix (including
 * an eventual enclosing class or C++11 enum class) is of a certain
 * length.
 *
 * @warning Needs to be specialized for each enum class type that
 * wants to use this. When no specialization is given, will return
 * 0. */
template<class Enum>
size_t eoffs_cls()
{
    return 0;
}


/** return the offset for an enum symbol prefix. This includes
 * eoffs_cls().  With this function you can announce that the full
 * prefix (including an eventual enclosing class or C++11 enum class
 * plus the string prefix) is of a certain length.
 *
 * @warning Needs to be specialized for each enum class type that
 * wants to use this. When no specialization is given, will return
 * 0. */
template<class Enum>
size_t eoffs_pfx()
{
    return 0;
}


template<class Enum>
size_t eoffs(EnumOffsetType which)
{
    switch(which)
    {
    case EOFFS_NONE:
        return 0;
    case EOFFS_CLS:
        return eoffs_cls<Enum>();
    case EOFFS_PFX:
    {
        size_t pfx = eoffs_pfx<Enum>();
        return pfx > 0 ? pfx : eoffs_cls<Enum>();
    }
    default:
        C4_ERROR("unknown offset type %d", (int)which);
        return 0;
    }
}


//-----------------------------------------------------------------------------
/** get the enum value corresponding to a c-string */

#ifdef __clang__
#   pragma clang diagnostic push
#elif defined(__GNUC__)
#   pragma GCC diagnostic push
#   if __GNUC__ >= 6
#       pragma GCC diagnostic ignored "-Wnull-dereference"
#   endif
#endif

template<class Enum>
Enum str2e(const char* str)
{
    auto pairs = esyms<Enum>();
    auto *p = pairs.get(str);
    C4_CHECK_MSG(p != nullptr, "no valid enum pair name for '%s'", str);
    return p->value;
}

/** get the c-string corresponding to an enum value */
template<class Enum>
const char* e2str(Enum e)
{
    auto es = esyms<Enum>();
    auto *p = es.get(e);
    C4_CHECK_MSG(p != nullptr, "no valid enum pair name");
    return p->name;
}

/** like e2str(), but add an offset. */
template<class Enum>
const char* e2stroffs(Enum e, EnumOffsetType ot=EOFFS_PFX)
{
    const char *s = e2str<Enum>(e) + eoffs<Enum>(ot);
    return s;
}

#ifdef __clang__
#   pragma clang diagnostic pop
#elif defined(__GNUC__)
#   pragma GCC diagnostic pop
#endif

//-----------------------------------------------------------------------------
/** Find a symbol by value. Returns nullptr when none is found */
template<class Enum>
typename EnumSymbols<Enum>::Sym const* EnumSymbols<Enum>::find(Enum v) const
{
    for(Sym const* p = this->m_symbols, *e = p+this->m_num; p < e; ++p)
        if(p->value == v)
            return p;
    return nullptr;
}

/** Find a symbol by name. Returns nullptr when none is found */
template<class Enum>
typename EnumSymbols<Enum>::Sym const* EnumSymbols<Enum>::find(const char *s) const
{
    for(Sym const* p = this->m_symbols, *e = p+this->m_num; p < e; ++p)
        if(p->cmp(s))
            return p;
    return nullptr;
}

/** Find a symbol by name. Returns nullptr when none is found */
template<class Enum>
typename EnumSymbols<Enum>::Sym const* EnumSymbols<Enum>::find(const char *s, size_t len) const
{
    for(Sym const* p = this->m_symbols, *e = p+this->m_num; p < e; ++p)
        if(p->cmp(s, len))
            return p;
    return nullptr;
}

//-----------------------------------------------------------------------------
template<class Enum>
bool EnumSymbols<Enum>::Sym::cmp(const char *s) const
{
    if(strcmp(name, s) == 0)
        return true;

    for(int i = 1; i < _EOFFS_LAST; ++i)
    {
        auto o = eoffs<Enum>((EnumOffsetType)i);
        if(o > 0)
            if(strcmp(name + o, s) == 0)
                return true;
    }

    return false;
}

template<class Enum>
bool EnumSymbols<Enum>::Sym::cmp(const char *s, size_t len) const
{
    if(strncmp(name, s, len) == 0)
        return true;

    size_t nlen = 0;
    for(int i = 1; i <_EOFFS_LAST; ++i)
    {
        auto o = eoffs<Enum>((EnumOffsetType)i);
        if(o > 0)
        {
            if(!nlen)
            {
                nlen = strlen(name);
            }
            C4_ASSERT(o < nlen);
            size_t rem = nlen - o;
            auto m = len > rem ? len : rem;
            if(len >= m && strncmp(name + o, s, m) == 0)
                return true;
        }
    }

    return false;
}

//-----------------------------------------------------------------------------
template<class Enum>
const char* EnumSymbols<Enum>::Sym::name_offs(EnumOffsetType t) const
{
    C4_ASSERT(eoffs<Enum>(t) < strlen(name));
    return name + eoffs<Enum>(t);
}

} // namespace c4

#endif // _C4_ENUM_HPP_


// (end https://github.com/biojppm/c4core/src/c4/enum.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/bitmask.hpp
// https://github.com/biojppm/c4core/src/c4/bitmask.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_BITMASK_HPP_
#define _C4_BITMASK_HPP_

/** @file bitmask.hpp bitmask utilities */

//included above:
//#include <cstring>
//included above:
//#include <type_traits>

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/enum.hpp
//#include "c4/enum.hpp"
#if !defined(C4_ENUM_HPP_) && !defined(_C4_ENUM_HPP_)
#error "amalgamate: file c4/enum.hpp must have been included at this point"
#endif /* C4_ENUM_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/format.hpp
//#include "c4/format.hpp"
#if !defined(C4_FORMAT_HPP_) && !defined(_C4_FORMAT_HPP_)
#error "amalgamate: file c4/format.hpp must have been included at this point"
#endif /* C4_FORMAT_HPP_ */


#ifdef _MSC_VER
#   pragma warning(push)
#   pragma warning(disable : 4996) // 'strncpy', fopen, etc: This function or variable may be unsafe
#elif defined(__clang__)
#elif defined(__GNUC__)
#   pragma GCC diagnostic push
#   if __GNUC__ >= 8
#       pragma GCC diagnostic ignored "-Wstringop-truncation"
#       pragma GCC diagnostic ignored "-Wstringop-overflow"
#   endif
#endif

namespace c4 {

//-----------------------------------------------------------------------------
/** write a bitmask to a stream, formatted as a string */

template<class Enum, class Stream>
Stream& bm2stream(Stream &s, typename std::underlying_type<Enum>::type bits, EnumOffsetType offst=EOFFS_PFX)
{
    using I = typename std::underlying_type<Enum>::type;
    bool written = false;

    auto const& pairs = esyms<Enum>();

    // write non null value
    if(bits)
    {
        // do reverse iteration to give preference to composite enum symbols,
        // which are likely to appear at the end of the enum sequence
        for(size_t i = pairs.size() - 1; i != size_t(-1); --i)
        {
            auto p = pairs[i];
            I b(static_cast<I>(p.value));
            if(b && (bits & b) == b)
            {
                if(written) s << '|'; // append bit-or character
                written = true;
                s << p.name_offs(offst); // append bit string
                bits &= ~b;
            }
        }
        return s;
    }
    else
    {
        // write a null value
        for(size_t i = pairs.size() - 1; i != size_t(-1); --i)
        {
            auto p = pairs[i];
            I b(static_cast<I>(p.value));
            if(b == 0)
            {
                s << p.name_offs(offst);
                written = true;
                break;
            }
        }
    }
    if(!written)
    {
        s << '0';
    }
    return s;
}

template<class Enum, class Stream>
typename std::enable_if<is_scoped_enum<Enum>::value, Stream&>::type
bm2stream(Stream &s, Enum value, EnumOffsetType offst=EOFFS_PFX)
{
    using I = typename std::underlying_type<Enum>::type;
    return bm2stream<Enum>(s, static_cast<I>(value), offst);
}


//-----------------------------------------------------------------------------

// some utility macros, undefed below

/// @cond dev

/* Execute `code` if the `num` of characters is available in the str
 * buffer. This macro simplifies the code for bm2str().
 * @todo improve performance by writing from the end and moving only once. */
#define _c4prependchars(code, num)                                      \
    if(str && (pos + num <= sz))                                        \
    {                                                                   \
        /* move the current string to the right */                      \
        memmove(str + num, str, pos);                                   \
        /* now write in the beginning of the string */                  \
        code;                                                           \
    }                                                                   \
    else if(str && sz)                                                  \
    {                                                                   \
        C4_ERROR("cannot write to string pos=%d num=%d sz=%d",          \
                 (int)pos, (int)num, (int)sz);                          \
    }                                                                   \
    pos += num

/* Execute `code` if the `num` of characters is available in the str
 * buffer. This macro simplifies the code for bm2str(). */
#define _c4appendchars(code, num)                                       \
    if(str && (pos + num <= sz))                                        \
    {                                                                   \
        code;                                                           \
    }                                                                   \
    else if(str && sz)                                                  \
    {                                                                   \
        C4_ERROR("cannot write to string pos=%d num=%d sz=%d",          \
                 (int)pos, (int)num, (int)sz);                          \
    }                                                                   \
    pos += num

/// @endcond


/** convert a bitmask to string.
 * return the number of characters written. To find the needed size,
 * call first with str=nullptr and sz=0 */
template<class Enum>
size_t bm2str
(
    typename std::underlying_type<Enum>::type bits,
    char *str=nullptr,
    size_t sz=0,
    EnumOffsetType offst=EOFFS_PFX
)
{
    using I = typename std::underlying_type<Enum>::type;
    C4_ASSERT((str == nullptr) == (sz == 0));

    auto syms = esyms<Enum>();
    size_t pos = 0;
    typename EnumSymbols<Enum>::Sym const* C4_RESTRICT zero = nullptr;

    // do reverse iteration to give preference to composite enum symbols,
    // which are likely to appear later in the enum sequence
    for(size_t i = syms.size()-1; i != size_t(-1); --i)
    {
        auto const &C4_RESTRICT p = syms[i]; // do not copy, we are assigning to `zero`
        I b = static_cast<I>(p.value);
        if(b == 0)
        {
            zero = &p; // save this symbol for later
        }
        else if((bits & b) == b)
        {
            bits &= ~b;
            // append bit-or character
            if(pos > 0)
            {
                _c4prependchars(*str = '|', 1);
            }
            // append bit string
            const char *pname = p.name_offs(offst);
            size_t len = strlen(pname);
            _c4prependchars(strncpy(str, pname, len), len);
        }
    }

    C4_CHECK_MSG(bits == 0, "could not find all bits");
    if(pos == 0) // make sure at least something is written
    {
        if(zero) // if we have a zero symbol, use that
        {
            const char *pname = zero->name_offs(offst);
            size_t len = strlen(pname);
            _c4prependchars(strncpy(str, pname, len), len);
        }
        else // otherwise just write an integer zero
        {
            _c4prependchars(*str = '0', 1);
        }
    }
    _c4appendchars(str[pos] = '\0', 1);

    return pos;
}


// cleanup!
#undef _c4appendchars
#undef _c4prependchars


/** scoped enums do not convert automatically to their underlying type,
 * so this SFINAE overload will accept scoped enum symbols and cast them
 * to the underlying type */
template<class Enum>
typename std::enable_if<is_scoped_enum<Enum>::value, size_t>::type
bm2str
(
    Enum bits,
    char *str=nullptr,
    size_t sz=0,
    EnumOffsetType offst=EOFFS_PFX
)
{
    using I = typename std::underlying_type<Enum>::type;
    return bm2str<Enum>(static_cast<I>(bits), str, sz, offst);
}


//-----------------------------------------------------------------------------

namespace detail {

#ifdef __clang__
#   pragma clang diagnostic push
#elif defined(__GNUC__)
#   pragma GCC diagnostic push
#   if __GNUC__ >= 6
#       pragma GCC diagnostic ignored "-Wnull-dereference"
#   endif
#endif

template<class Enum>
typename std::underlying_type<Enum>::type str2bm_read_one(const char *str, size_t sz, bool alnum)
{
    using I = typename std::underlying_type<Enum>::type;
    auto pairs = esyms<Enum>();
    if(alnum)
    {
        auto *p = pairs.find(str, sz);
        C4_CHECK_MSG(p != nullptr, "no valid enum pair name for '%.*s'", (int)sz, str);
        return static_cast<I>(p->value);
    }
    I tmp;
    size_t len = uncat(csubstr(str, sz), tmp);
    C4_CHECK_MSG(len != csubstr::npos, "could not read string as an integral type: '%.*s'", (int)sz, str);
    return tmp;
}

#ifdef __clang__
#   pragma clang diagnostic pop
#elif defined(__GNUC__)
#   pragma GCC diagnostic pop
#endif
} // namespace detail

/** convert a string to a bitmask */
template<class Enum>
typename std::underlying_type<Enum>::type str2bm(const char *str, size_t sz)
{
    using I = typename std::underlying_type<Enum>::type;

    I val = 0;
    bool started = false;
    bool alnum = false, num = false;
    const char *f = nullptr, *pc = str;
    for( ; pc < str+sz; ++pc)
    {
        const char c = *pc;
        if((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || c == '_')
        {
            C4_CHECK(( ! num) || ((pc - f) == 1 && (c == 'x' || c == 'X'))); // accept hexadecimal numbers
            if( ! started)
            {
                f = pc;
                alnum = started = true;
            }
        }
        else if(c >= '0' && c <= '9')
        {
            C4_CHECK( ! alnum);
            if(!started)
            {
                f = pc;
                num = started = true;
            }
        }
        else if(c == ':' || c == ' ')
        {
            // skip this char
        }
        else if(c == '|' || c == '\0')
        {
            C4_ASSERT(num != alnum);
            C4_ASSERT(pc >= f);
            val |= detail::str2bm_read_one<Enum>(f, static_cast<size_t>(pc-f), alnum);
            started = num = alnum = false;
            if(c == '\0')
            {
                return val;
            }
        }
        else
        {
            C4_ERROR("bad character '%c' in bitmask string", c);
        }
    }

    if(f)
    {
        C4_ASSERT(num != alnum);
        C4_ASSERT(pc >= f);
        val |= detail::str2bm_read_one<Enum>(f, static_cast<size_t>(pc-f), alnum);
    }

    return val;
}

/** convert a string to a bitmask */
template<class Enum>
typename std::underlying_type<Enum>::type str2bm(const char *str)
{
    return str2bm<Enum>(str, strlen(str));
}

} // namespace c4

#ifdef _MSC_VER
#   pragma warning(pop)
#elif defined(__clang__)
#elif defined(__GNUC__)
#   pragma GCC diagnostic pop
#endif

#endif // _C4_BITMASK_HPP_


// (end https://github.com/biojppm/c4core/src/c4/bitmask.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/span.hpp
// https://github.com/biojppm/c4core/src/c4/span.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_SPAN_HPP_
#define _C4_SPAN_HPP_

/** @file span.hpp Provides span classes. */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/config.hpp
//#include "c4/config.hpp"
#if !defined(C4_CONFIG_HPP_) && !defined(_C4_CONFIG_HPP_)
#error "amalgamate: file c4/config.hpp must have been included at this point"
#endif /* C4_CONFIG_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/error.hpp
//#include "c4/error.hpp"
#if !defined(C4_ERROR_HPP_) && !defined(_C4_ERROR_HPP_)
#error "amalgamate: file c4/error.hpp must have been included at this point"
#endif /* C4_ERROR_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/szconv.hpp
//#include "c4/szconv.hpp"
#if !defined(C4_SZCONV_HPP_) && !defined(_C4_SZCONV_HPP_)
#error "amalgamate: file c4/szconv.hpp must have been included at this point"
#endif /* C4_SZCONV_HPP_ */


//included above:
//#include <algorithm>

namespace c4 {

//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
/** a crtp base for implementing span classes
 *
 * A span is a non-owning range of elements contiguously stored in memory.
 * Unlike STL's array_view, the span allows write-access to its members.
 *
 * To obtain subspans from a span, the following const member functions
 * are available:
 *  - subspan(first, num)
 *  - range(first, last)
 *  - first(num)
 *  - last(num)
 *
 * A span can also be resized via the following non-const member functions:
 *  - resize(sz)
 *  - ltrim(num)
 *  - rtrim(num)
 *
 * @see span
 * @see cspan
 * @see spanrs
 * @see cspanrs
 * @see spanrsl
 * @see cspanrsl
 */
template<class T, class I, class SpanImpl>
class span_crtp
{
// some utility defines, undefined at the end of this class
#define _c4this  ((SpanImpl      *)this)
#define _c4cthis ((SpanImpl const*)this)
#define _c4ptr   ((SpanImpl      *)this)->m_ptr
#define _c4cptr  ((SpanImpl const*)this)->m_ptr
#define _c4sz    ((SpanImpl      *)this)->m_size
#define _c4csz   ((SpanImpl const*)this)->m_size

public:

    _c4_DEFINE_ARRAY_TYPES(T, I);

public:

    C4_ALWAYS_INLINE constexpr I value_size() const noexcept { return sizeof(T); }
    C4_ALWAYS_INLINE constexpr I elm_size  () const noexcept { return sizeof(T); }
    C4_ALWAYS_INLINE constexpr I type_size () const noexcept { return sizeof(T); }
    C4_ALWAYS_INLINE           I byte_size () const noexcept { return _c4csz*sizeof(T); }

    C4_ALWAYS_INLINE bool empty()    const noexcept { return _c4csz == 0; }
    C4_ALWAYS_INLINE I    size()     const noexcept { return _c4csz; }
    //C4_ALWAYS_INLINE I    capacity() const noexcept { return _c4sz; } // this must be defined by impl classes

    C4_ALWAYS_INLINE void clear() noexcept { _c4sz = 0; }

    C4_ALWAYS_INLINE T      * data()       noexcept { return _c4ptr; }
    C4_ALWAYS_INLINE T const* data() const noexcept { return _c4cptr; }

    C4_ALWAYS_INLINE       iterator  begin()       noexcept { return _c4ptr; }
    C4_ALWAYS_INLINE const_iterator  begin() const noexcept { return _c4cptr; }
    C4_ALWAYS_INLINE const_iterator cbegin() const noexcept { return _c4cptr; }

    C4_ALWAYS_INLINE       iterator  end()       noexcept { return _c4ptr  + _c4sz; }
    C4_ALWAYS_INLINE const_iterator  end() const noexcept { return _c4cptr + _c4csz; }
    C4_ALWAYS_INLINE const_iterator cend() const noexcept { return _c4cptr + _c4csz; }

    C4_ALWAYS_INLINE       reverse_iterator  rbegin()       noexcept { return reverse_iterator(_c4ptr + _c4sz); }
    C4_ALWAYS_INLINE const_reverse_iterator  rbegin() const noexcept { return reverse_iterator(_c4cptr + _c4sz); }
    C4_ALWAYS_INLINE const_reverse_iterator crbegin() const noexcept { return reverse_iterator(_c4cptr + _c4sz); }

    C4_ALWAYS_INLINE       reverse_iterator  rend()       noexcept { return const_reverse_iterator(_c4ptr); }
    C4_ALWAYS_INLINE const_reverse_iterator  rend() const noexcept { return const_reverse_iterator(_c4cptr); }
    C4_ALWAYS_INLINE const_reverse_iterator crend() const noexcept { return const_reverse_iterator(_c4cptr); }

    C4_ALWAYS_INLINE T      & front()       C4_NOEXCEPT_X { C4_XASSERT(!empty()); return _c4ptr [0]; }
    C4_ALWAYS_INLINE T const& front() const C4_NOEXCEPT_X { C4_XASSERT(!empty()); return _c4cptr[0]; }

    C4_ALWAYS_INLINE T      & back()       C4_NOEXCEPT_X { C4_XASSERT(!empty()); return _c4ptr [_c4sz  - 1]; }
    C4_ALWAYS_INLINE T const& back() const C4_NOEXCEPT_X { C4_XASSERT(!empty()); return _c4cptr[_c4csz - 1]; }

    C4_ALWAYS_INLINE T      & operator[] (I i)       C4_NOEXCEPT_X { C4_XASSERT(i >= 0 && i < _c4sz ); return _c4ptr [i]; }
    C4_ALWAYS_INLINE T const& operator[] (I i) const C4_NOEXCEPT_X { C4_XASSERT(i >= 0 && i < _c4csz); return _c4cptr[i]; }

    C4_ALWAYS_INLINE SpanImpl subspan(I first, I num) const C4_NOEXCEPT_X
    {
        C4_XASSERT((first >= 0 && first < _c4csz) || (first == _c4csz && num == 0));
        C4_XASSERT((first + num >= 0) && (first + num <= _c4csz));
        return _c4cthis->_select(_c4cptr + first, num);
    }
    C4_ALWAYS_INLINE SpanImpl subspan(I first) const C4_NOEXCEPT_X ///< goes up until the end of the span
    {
        C4_XASSERT(first >= 0 && first <= _c4csz);
        return _c4cthis->_select(_c4cptr + first, _c4csz - first);
    }

    C4_ALWAYS_INLINE SpanImpl range(I first, I last) const C4_NOEXCEPT_X ///< last element is NOT included
    {
        C4_XASSERT(((first >= 0) && (first < _c4csz)) || (first == _c4csz && first == last));
        C4_XASSERT((last >= 0) && (last <= _c4csz));
        C4_XASSERT(last >= first);
        return _c4cthis->_select(_c4cptr + first, last - first);
    }
    C4_ALWAYS_INLINE SpanImpl range(I first) const C4_NOEXCEPT_X ///< goes up until the end of the span
    {
        C4_XASSERT(((first >= 0) && (first <= _c4csz)));
        return _c4cthis->_select(_c4cptr + first, _c4csz - first);
    }

    C4_ALWAYS_INLINE SpanImpl first(I num) const C4_NOEXCEPT_X ///< get the first num elements, starting at 0
    {
        C4_XASSERT((num >= 0) && (num <= _c4csz));
        return _c4cthis->_select(_c4cptr, num);
    }
    C4_ALWAYS_INLINE SpanImpl last(I num) const C4_NOEXCEPT_X ///< get the last num elements, starting at size()-num
    {
        C4_XASSERT((num >= 0) && (num <= _c4csz));
        return _c4cthis->_select(_c4cptr + _c4csz - num, num);
    }

    bool is_subspan(span_crtp const& ss) const noexcept
    {
        if(_c4cptr == nullptr) return false;
        auto *b = begin(), *e = end();
        auto *ssb = ss.begin(), *sse = ss.end();
        if(ssb >= b && sse <= e)
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    /** COMPLement Left: return the complement to the left of the beginning of the given subspan.
     * If ss does not begin inside this, returns an empty substring. */
    SpanImpl compll(span_crtp const& ss) const C4_NOEXCEPT_X
    {
        auto ssb = ss.begin();
        auto b = begin();
        auto e = end();
        if(ssb >= b && ssb <= e)
        {
            return subspan(0, static_cast<size_t>(ssb - b));
        }
        else
        {
            return subspan(0, 0);
        }
    }

    /** COMPLement Right: return the complement to the right of the end of the given subspan.
     * If ss does not end inside this, returns an empty substring. */
    SpanImpl complr(span_crtp const& ss) const C4_NOEXCEPT_X
    {
        auto sse = ss.end();
        auto b = begin();
        auto e = end();
        if(sse >= b && sse <= e)
        {
            return subspan(static_cast<size_t>(sse - b), static_cast<size_t>(e - sse));
        }
        else
        {
            return subspan(0, 0);
        }
    }

    C4_ALWAYS_INLINE bool same_span(span_crtp const& that) const noexcept
    {
        return size() == that.size() && data() == that.data();
    }
    template<class I2, class Impl2>
    C4_ALWAYS_INLINE bool same_span(span_crtp<T, I2, Impl2> const& that) const C4_NOEXCEPT_X
    {
        I tsz = szconv<I>(that.size()); // x-asserts that the size does not overflow
        return size() == tsz && data() == that.data();
    }

#undef _c4this
#undef _c4cthis
#undef _c4ptr
#undef _c4cptr
#undef _c4sz
#undef _c4csz
};

//-----------------------------------------------------------------------------
template<class T, class Il, class Ir, class _Impll, class _Implr>
inline constexpr bool operator==
(
    span_crtp<T, Il, _Impll> const& l,
    span_crtp<T, Ir, _Implr> const& r
)
{
#if C4_CPP >= 14
    return std::equal(l.begin(), l.end(), r.begin(), r.end());
#else
    return l.same_span(r) || std::equal(l.begin(), l.end(), r.begin());
#endif
}

template<class T, class Il, class Ir, class _Impll, class _Implr>
inline constexpr bool operator!=
(
    span_crtp<T, Il, _Impll> const& l,
    span_crtp<T, Ir, _Implr> const& r
)
{
    return ! (l == r);
}

//-----------------------------------------------------------------------------
template<class T, class Il, class Ir, class _Impll, class _Implr>
inline constexpr bool operator<
(
    span_crtp<T, Il, _Impll> const& l,
    span_crtp<T, Ir, _Implr> const& r
)
{
    return std::lexicographical_compare(l.begin(), l.end(), r.begin(), r.end());
}

template<class T, class Il, class Ir, class _Impll, class _Implr>
inline constexpr bool operator<=
(
    span_crtp<T, Il, _Impll> const& l,
    span_crtp<T, Ir, _Implr> const& r
)
{
    return ! (l > r);
}

//-----------------------------------------------------------------------------
template<class T, class Il, class Ir, class _Impll, class _Implr>
inline constexpr bool operator>
(
    span_crtp<T, Il, _Impll> const& l,
    span_crtp<T, Ir, _Implr> const& r
)
{
    return r < l;
}

//-----------------------------------------------------------------------------
template<class T, class Il, class Ir, class _Impll, class _Implr>
inline constexpr bool operator>=
(
    span_crtp<T, Il, _Impll> const& l,
    span_crtp<T, Ir, _Implr> const& r
)
{
    return ! (l < r);
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
/** A non-owning span of elements contiguously stored in memory. */
template<class T, class I=C4_SIZE_TYPE>
class span : public span_crtp<T, I, span<T, I>>
{
    friend class span_crtp<T, I, span<T, I>>;

    T * C4_RESTRICT m_ptr;
    I   m_size;

    C4_ALWAYS_INLINE span _select(T *p, I sz) const { return span(p, sz); }

public:

    _c4_DEFINE_ARRAY_TYPES(T, I);
    using NCT = typename std::remove_const<T>::type; //!< NCT=non const type
    using CT = typename std::add_const<T>::type; //!< CT=const type
    using const_type = span<CT, I>;

    /// convert automatically to span of const T
    operator span<CT, I> () const { span<CT, I> s(m_ptr, m_size); return s; }

public:

    C4_ALWAYS_INLINE C4_CONSTEXPR14 span() noexcept : m_ptr{nullptr}, m_size{0} {}

    span(span const&) = default;
    span(span     &&) = default;

    span& operator= (span const&) = default;
    span& operator= (span     &&) = default;

public:

    /** @name Construction and assignment from same type */
    /** @{ */

    template<size_t N> C4_ALWAYS_INLINE C4_CONSTEXPR14      span  (T (&arr)[N]) noexcept : m_ptr{arr}, m_size{N} {}
    template<size_t N> C4_ALWAYS_INLINE C4_CONSTEXPR14 void assign(T (&arr)[N]) noexcept { m_ptr = arr; m_size = N; }

    C4_ALWAYS_INLINE C4_CONSTEXPR14        span(T *p, I sz) noexcept : m_ptr{p}, m_size{sz} {}
    C4_ALWAYS_INLINE C4_CONSTEXPR14 void   assign(T *p, I sz) noexcept { m_ptr = p; m_size = sz; }

    C4_ALWAYS_INLINE C4_CONSTEXPR14      span  (c4::aggregate_t, std::initializer_list<T> il) noexcept : m_ptr{&*il.begin()}, m_size{il.size()} {}
    C4_ALWAYS_INLINE C4_CONSTEXPR14 void assign(c4::aggregate_t, std::initializer_list<T> il) noexcept { m_ptr = &*il.begin(); m_size = il.size(); }

    /** @} */

public:

    C4_ALWAYS_INLINE I capacity() const noexcept { return m_size; }

    C4_ALWAYS_INLINE void resize(I sz) C4_NOEXCEPT_A { C4_ASSERT(sz <= m_size); m_size = sz; }
    C4_ALWAYS_INLINE void rtrim (I n ) C4_NOEXCEPT_A { C4_ASSERT(n >= 0 && n < m_size); m_size -= n; }
    C4_ALWAYS_INLINE void ltrim (I n ) C4_NOEXCEPT_A { C4_ASSERT(n >= 0 && n < m_size); m_size -= n; m_ptr += n; }

};
template<class T, class I=C4_SIZE_TYPE> using cspan = span<const T, I>;


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
/** A non-owning span resizeable up to a capacity. Subselection or resizing
 * will keep the original provided it starts at begin(). If subselection or
 * resizing change the pointer, then the original capacity information will
 * be lost.
 *
 * Thus, resizing via resize() and ltrim() and subselecting via first()
 * or any of subspan() or range() when starting from the beginning will keep
 * the original capacity. OTOH, using last(), or any of subspan() or range()
 * with an offset from the start will remove from capacity (shifting the
 * pointer) by the corresponding offset. If this is undesired, then consider
 * using spanrsl.
 *
 * @see spanrs for a span resizeable on the right
 * @see spanrsl for a span resizeable on the right and left
 */

template<class T, class I=C4_SIZE_TYPE>
class spanrs : public span_crtp<T, I, spanrs<T, I>>
{
    friend class span_crtp<T, I, spanrs<T, I>>;

    T * C4_RESTRICT m_ptr;
    I   m_size;
    I   m_capacity;

    C4_ALWAYS_INLINE spanrs _select(T *p, I sz) const noexcept
    {
        C4_ASSERT(p >= m_ptr);
        size_t delta = static_cast<size_t>(p - m_ptr);
        C4_ASSERT(m_capacity >= delta);
        return spanrs(p, sz, static_cast<size_t>(m_capacity - delta));
    }

public:

    _c4_DEFINE_ARRAY_TYPES(T, I);
    using NCT = typename std::remove_const<T>::type; //!< NCT=non const type
    using CT = typename std::add_const<T>::type; //!< CT=const type
    using const_type = spanrs<CT, I>;

    /// convert automatically to span of T
    C4_ALWAYS_INLINE operator span<T, I > () const noexcept { return span<T, I>(m_ptr, m_size); }
    /// convert automatically to span of const T
    //C4_ALWAYS_INLINE operator span<CT, I> () const noexcept { span<CT, I> s(m_ptr, m_size); return s; }
    /// convert automatically to spanrs of const T
    C4_ALWAYS_INLINE operator spanrs<CT, I> () const noexcept { spanrs<CT, I> s(m_ptr, m_size, m_capacity); return s; }

public:

    C4_ALWAYS_INLINE spanrs() noexcept : m_ptr{nullptr}, m_size{0}, m_capacity{0} {}

    spanrs(spanrs const&) = default;
    spanrs(spanrs     &&) = default;

    spanrs& operator= (spanrs const&) = default;
    spanrs& operator= (spanrs     &&) = default;

public:

    /** @name Construction and assignment from same type */
    /** @{ */

    C4_ALWAYS_INLINE      spanrs(T *p, I sz) noexcept : m_ptr{p}, m_size{sz}, m_capacity{sz} {}
    /** @warning will reset the capacity to sz */
    C4_ALWAYS_INLINE void assign(T *p, I sz) noexcept { m_ptr = p; m_size = sz; m_capacity = sz; }

    C4_ALWAYS_INLINE      spanrs(T *p, I sz, I cap) noexcept : m_ptr{p}, m_size{sz}, m_capacity{cap} {}
    C4_ALWAYS_INLINE void assign(T *p, I sz, I cap) noexcept { m_ptr = p; m_size = sz; m_capacity = cap; }

    template<size_t N> C4_ALWAYS_INLINE      spanrs(T (&arr)[N]) noexcept : m_ptr{arr}, m_size{N}, m_capacity{N} {}
    template<size_t N> C4_ALWAYS_INLINE void assign(T (&arr)[N]) noexcept { m_ptr = arr; m_size = N; m_capacity = N; }

    C4_ALWAYS_INLINE      spanrs(c4::aggregate_t, std::initializer_list<T> il) noexcept : m_ptr{il.begin()}, m_size{il.size()}, m_capacity{il.size()} {}
    C4_ALWAYS_INLINE void assign(c4::aggregate_t, std::initializer_list<T> il) noexcept { m_ptr = il.begin(); m_size = il.size(); m_capacity = il.size(); }

    /** @} */

public:

    C4_ALWAYS_INLINE I capacity() const noexcept { return m_capacity; }

    C4_ALWAYS_INLINE void resize(I sz) C4_NOEXCEPT_A { C4_ASSERT(sz <= m_capacity); m_size = sz; }
    C4_ALWAYS_INLINE void rtrim (I n ) C4_NOEXCEPT_A { C4_ASSERT(n >= 0 && n < m_size); m_size -= n; }
    C4_ALWAYS_INLINE void ltrim (I n ) C4_NOEXCEPT_A { C4_ASSERT(n >= 0 && n < m_size); m_size -= n; m_ptr += n; m_capacity -= n; }

};
template<class T, class I=C4_SIZE_TYPE> using cspanrs = spanrs<const T, I>;


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
/** A non-owning span which always retains the capacity of the original
 * range it was taken from (though it may loose its original size).
 * The resizing methods resize(), ltrim(), rtrim() as well
 * as the subselection methods subspan(), range(), first() and last() can be
 * used at will without loosing the original capacity; the full capacity span
 * can always be recovered by calling original().
 */
template<class T, class I=C4_SIZE_TYPE>
class spanrsl : public span_crtp<T, I, spanrsl<T, I>>
{
    friend class span_crtp<T, I, spanrsl<T, I>>;

    T *C4_RESTRICT m_ptr;      ///< the current ptr. the original ptr is (m_ptr - m_offset).
    I   m_size;     ///< the current size. the original size is unrecoverable.
    I   m_capacity; ///< the current capacity. the original capacity is (m_capacity + m_offset).
    I   m_offset;   ///< the offset of the current m_ptr to the start of the original memory block.

    C4_ALWAYS_INLINE spanrsl _select(T *p, I sz) const noexcept
    {
        C4_ASSERT(p >= m_ptr);
        I delta = static_cast<I>(p - m_ptr);
        C4_ASSERT(m_capacity >= delta);
        return spanrsl(p, sz, static_cast<I>(m_capacity - delta), m_offset + delta);
    }

public:

    _c4_DEFINE_ARRAY_TYPES(T, I);
    using NCT = typename std::remove_const<T>::type; //!< NCT=non const type
    using CT = typename std::add_const<T>::type; //!< CT=const type
    using const_type = spanrsl<CT, I>;

    C4_ALWAYS_INLINE operator span<T, I> () const noexcept { return span<T, I>(m_ptr, m_size); }
    C4_ALWAYS_INLINE operator spanrs<T, I> () const noexcept { return spanrs<T, I>(m_ptr, m_size, m_capacity); }
    C4_ALWAYS_INLINE operator spanrsl<CT, I> () const noexcept { return spanrsl<CT, I>(m_ptr, m_size, m_capacity, m_offset); }

public:

    C4_ALWAYS_INLINE spanrsl() noexcept : m_ptr{nullptr}, m_size{0}, m_capacity{0}, m_offset{0} {}

    spanrsl(spanrsl const&) = default;
    spanrsl(spanrsl     &&) = default;

    spanrsl& operator= (spanrsl const&) = default;
    spanrsl& operator= (spanrsl     &&) = default;

public:

    C4_ALWAYS_INLINE     spanrsl(T *p, I sz) noexcept : m_ptr{p}, m_size{sz}, m_capacity{sz}, m_offset{0} {}
    C4_ALWAYS_INLINE void assign(T *p, I sz) noexcept { m_ptr = p; m_size = sz; m_capacity = sz; m_offset = 0; }

    C4_ALWAYS_INLINE     spanrsl(T *p, I sz, I cap) noexcept : m_ptr{p}, m_size{sz}, m_capacity{cap}, m_offset{0} {}
    C4_ALWAYS_INLINE void assign(T *p, I sz, I cap) noexcept { m_ptr = p; m_size = sz; m_capacity = cap; m_offset = 0; }

    C4_ALWAYS_INLINE     spanrsl(T *p, I sz, I cap, I offs) noexcept : m_ptr{p}, m_size{sz}, m_capacity{cap}, m_offset{offs} {}
    C4_ALWAYS_INLINE void assign(T *p, I sz, I cap, I offs) noexcept { m_ptr = p; m_size = sz; m_capacity = cap; m_offset = offs; }

    template<size_t N> C4_ALWAYS_INLINE     spanrsl(T (&arr)[N]) noexcept : m_ptr{arr}, m_size{N}, m_capacity{N}, m_offset{0} {}
    template<size_t N> C4_ALWAYS_INLINE void assign(T (&arr)[N]) noexcept { m_ptr = arr; m_size = N; m_capacity = N; m_offset = 0; }

    C4_ALWAYS_INLINE      spanrsl(c4::aggregate_t, std::initializer_list<T> il) noexcept : m_ptr{il.begin()}, m_size{il.size()}, m_capacity{il.size()}, m_offset{0} {}
    C4_ALWAYS_INLINE void assign (c4::aggregate_t, std::initializer_list<T> il) noexcept { m_ptr = il.begin(); m_size = il.size(); m_capacity = il.size(); m_offset = 0; }

public:

    C4_ALWAYS_INLINE I offset() const noexcept { return m_offset; }
    C4_ALWAYS_INLINE I capacity() const noexcept { return m_capacity; }

    C4_ALWAYS_INLINE void resize(I sz) C4_NOEXCEPT_A { C4_ASSERT(sz <= m_capacity); m_size = sz; }
    C4_ALWAYS_INLINE void rtrim (I n ) C4_NOEXCEPT_A { C4_ASSERT(n >= 0 && n < m_size); m_size -= n; }
    C4_ALWAYS_INLINE void ltrim (I n ) C4_NOEXCEPT_A { C4_ASSERT(n >= 0 && n < m_size); m_size -= n; m_ptr += n; m_offset += n; m_capacity -= n; }

    /** recover the original span as an spanrsl */
    C4_ALWAYS_INLINE spanrsl original() const
    {
        return spanrsl(m_ptr - m_offset, m_capacity + m_offset, m_capacity + m_offset, 0);
    }
    /** recover the original span as a different span type. Example: spanrs<...> orig = s.original<spanrs>(); */
    template<template<class, class> class OtherSpanType>
    C4_ALWAYS_INLINE OtherSpanType<T, I> original()
    {
        return OtherSpanType<T, I>(m_ptr - m_offset, m_capacity + m_offset);
    }
};
template<class T, class I=C4_SIZE_TYPE> using cspanrsl = spanrsl<const T, I>;


} // namespace c4


#endif /* _C4_SPAN_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/span.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/type_name.hpp
// https://github.com/biojppm/c4core/src/c4/type_name.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_TYPENAME_HPP_
#define _C4_TYPENAME_HPP_

/** @file type_name.hpp compile-time type name */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/span.hpp
//#include "c4/span.hpp"
#if !defined(C4_SPAN_HPP_) && !defined(_C4_SPAN_HPP_)
#error "amalgamate: file c4/span.hpp must have been included at this point"
#endif /* C4_SPAN_HPP_ */


/// @cond dev
struct _c4t
{
    const char *str;
    size_t sz;
    template<size_t N>
    constexpr _c4t(const char (&s)[N]) : str(s), sz(N-1) {} // take off the \0
};
// this is a more abbreviated way of getting the type name
// (if we used span in the return type, the name would involve
// templates and would create longer type name strings,
// as well as larger differences between compilers)
template<class T>
C4_CONSTEXPR14 C4_ALWAYS_INLINE
_c4t _c4tn()
{
    auto p = _c4t(C4_PRETTY_FUNC);
    return p;
}
/// @endcond


namespace c4 {

/** compile-time type name
 * @see http://stackoverflow.com/a/20170989/5875572 */
template<class T>
C4_CONSTEXPR14 cspan<char> type_name()
{
    const _c4t p = _c4tn<T>();

#if (0) // _C4_THIS_IS_A_DEBUG_SCAFFOLD
    for(size_t index = 0; index < p.sz; ++index)
    {
        printf(" %2c", p.str[index]);
    }
    printf("\n");
    for(size_t index = 0; index < p.sz; ++index)
    {
        printf(" %2d", (int)index);
    }
    printf("\n");
#endif

#if defined(_MSC_VER)
#   if defined(__clang__) // Visual Studio has the clang toolset
    // example:
    // ..........................xxx.
    // _c4t __cdecl _c4tn() [T = int]
    enum : size_t { tstart = 26, tend = 1};

#   elif defined(C4_MSVC_2015) || defined(C4_MSVC_2017) || defined(C4_MSVC_2019) || defined(C4_MSVC_2022)
    // Note: subtract 7 at the end because the function terminates with ">(void)" in VS2015+
    cspan<char>::size_type tstart = 26, tend = 7;

    const char *s = p.str + tstart; // look at the start

    // we're not using strcmp() or memcmp() to spare the #include

    // does it start with 'class '?
    if(p.sz > 6 && s[0] == 'c' && s[1] == 'l' && s[2] == 'a' && s[3] == 's' && s[4] == 's' && s[5] == ' ')
    {
        tstart += 6;
    }
    // does it start with 'struct '?
    else if(p.sz > 7 && s[0] == 's' && s[1] == 't' && s[2] == 'r' && s[3] == 'u' && s[4] == 'c' && s[5] == 't' && s[6] == ' ')
    {
        tstart += 7;
    }

#   else
    C4_NOT_IMPLEMENTED();
#   endif

#elif defined(__ICC)
    // example:
    // ........................xxx.
    // "_c4t _c4tn() [with T = int]"
    enum : size_t { tstart = 23, tend = 1};

#elif defined(__clang__)
    // example:
    // ...................xxx.
    // "_c4t _c4tn() [T = int]"
    enum : size_t { tstart = 18, tend = 1};

#elif defined(__GNUC__)
    #if __GNUC__ >= 7 && C4_CPP >= 14
        // example:
        // ..................................xxx.
        // "constexpr _c4t _c4tn() [with T = int]"
        enum : size_t { tstart = 33, tend = 1 };
    #else
        // example:
        // ........................xxx.
        // "_c4t _c4tn() [with T = int]"
        enum : size_t { tstart = 23, tend = 1 };
    #endif
#else
    C4_NOT_IMPLEMENTED();
#endif

    cspan<char> o(p.str + tstart, p.sz - tstart - tend);

    return o;
}

/** compile-time type name
 * @overload */
template<class T>
C4_CONSTEXPR14 C4_ALWAYS_INLINE cspan<char> type_name(T const&)
{
    return type_name<T>();
}

} // namespace c4

#endif //_C4_TYPENAME_HPP_


// (end https://github.com/biojppm/c4core/src/c4/type_name.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/base64.hpp
// https://github.com/biojppm/c4core/src/c4/base64.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_BASE64_HPP_
#define _C4_BASE64_HPP_

/** @file base64.hpp encoding/decoding for base64.
 * @see https://en.wikipedia.org/wiki/Base64
 * @see https://www.base64encode.org/
 * */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/charconv.hpp
//#include "c4/charconv.hpp"
#if !defined(C4_CHARCONV_HPP_) && !defined(_C4_CHARCONV_HPP_)
#error "amalgamate: file c4/charconv.hpp must have been included at this point"
#endif /* C4_CHARCONV_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/blob.hpp
//#include "c4/blob.hpp"
#if !defined(C4_BLOB_HPP_) && !defined(_C4_BLOB_HPP_)
#error "amalgamate: file c4/blob.hpp must have been included at this point"
#endif /* C4_BLOB_HPP_ */


namespace c4 {

/** check that the given buffer is a valid base64 encoding
 * @see https://en.wikipedia.org/wiki/Base64 */
bool base64_valid(csubstr encoded);

/** base64-encode binary data.
 * @param encoded [out] output buffer for encoded data
 * @param data [in] the input buffer with the binary data
 * @return the number of bytes needed to return the output. No writes occur beyond the end of the output buffer.
 * @see https://en.wikipedia.org/wiki/Base64 */
size_t base64_encode(substr encoded, cblob data);

/** decode the base64 encoding in the given buffer
 * @param encoded [in] the encoded base64
 * @param data [out] the output buffer
 * @return the number of bytes needed to return the output.. No writes occur beyond the end of the output buffer.
 * @see https://en.wikipedia.org/wiki/Base64 */
size_t base64_decode(csubstr encoded, blob data);


namespace fmt {

template<typename CharOrConstChar>
struct base64_wrapper_
{
    blob_<CharOrConstChar> data;
    base64_wrapper_() : data() {}
    base64_wrapper_(blob_<CharOrConstChar> blob) : data(blob) {}
};
using const_base64_wrapper = base64_wrapper_<cbyte>;
using base64_wrapper = base64_wrapper_<byte>;


/** mark a variable to be written in base64 format */
template<class ...Args>
C4_ALWAYS_INLINE const_base64_wrapper cbase64(Args const& C4_RESTRICT ...args)
{
    return const_base64_wrapper(cblob(args...));
}
/** mark a csubstr to be written in base64 format */
C4_ALWAYS_INLINE const_base64_wrapper cbase64(csubstr s)
{
    return const_base64_wrapper(cblob(s.str, s.len));
}
/** mark a variable to be written in base64 format */
template<class ...Args>
C4_ALWAYS_INLINE const_base64_wrapper base64(Args const& C4_RESTRICT ...args)
{
    return const_base64_wrapper(cblob(args...));
}
/** mark a csubstr to be written in base64 format */
C4_ALWAYS_INLINE const_base64_wrapper base64(csubstr s)
{
    return const_base64_wrapper(cblob(s.str, s.len));
}

/** mark a variable to be read in base64 format */
template<class ...Args>
C4_ALWAYS_INLINE base64_wrapper base64(Args &... args)
{
    return base64_wrapper(blob(args...));
}
/** mark a variable to be read in base64 format */
C4_ALWAYS_INLINE base64_wrapper base64(substr s)
{
    return base64_wrapper(blob(s.str, s.len));
}

} // namespace fmt


/** write a variable in base64 format */
inline size_t to_chars(substr buf, fmt::const_base64_wrapper b)
{
    return base64_encode(buf, b.data);
}

/** read a variable in base64 format */
inline size_t from_chars(csubstr buf, fmt::base64_wrapper *b)
{
    return base64_decode(buf, b->data);
}

} // namespace c4

#endif /* _C4_BASE64_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/base64.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/std/string.hpp
// https://github.com/biojppm/c4core/src/c4/std/string.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_STD_STRING_HPP_
#define _C4_STD_STRING_HPP_

/** @file string.hpp */

#ifndef C4CORE_SINGLE_HEADER
// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/substr.hpp
//#include "c4/substr.hpp"
#if !defined(C4_SUBSTR_HPP_) && !defined(_C4_SUBSTR_HPP_)
#error "amalgamate: file c4/substr.hpp must have been included at this point"
#endif /* C4_SUBSTR_HPP_ */

#endif

//included above:
//#include <string>

namespace c4 {

//-----------------------------------------------------------------------------

/** get a writeable view to an existing std::string.
 * When the string is empty, the returned view will be pointing
 * at the character with value '\0', but the size will be zero.
 * @see https://en.cppreference.com/w/cpp/string/basic_string/operator_at
 */
C4_ALWAYS_INLINE c4::substr to_substr(std::string &s) noexcept
{
    #if C4_CPP < 11
    #error this function will do undefined behavior
    #endif
    // since c++11 it is legal to call s[s.size()].
    return c4::substr(&s[0], s.size());
}

/** get a readonly view to an existing std::string.
 * When the string is empty, the returned view will be pointing
 * at the character with value '\0', but the size will be zero.
 * @see https://en.cppreference.com/w/cpp/string/basic_string/operator_at
 */
C4_ALWAYS_INLINE c4::csubstr to_csubstr(std::string const& s) noexcept
{
    #if C4_CPP < 11
    #error this function will do undefined behavior
    #endif
    // since c++11 it is legal to call s[s.size()].
    return c4::csubstr(&s[0], s.size());
}

//-----------------------------------------------------------------------------

C4_ALWAYS_INLINE bool operator== (c4::csubstr ss, std::string const& s) { return ss.compare(to_csubstr(s)) == 0; }
C4_ALWAYS_INLINE bool operator!= (c4::csubstr ss, std::string const& s) { return ss.compare(to_csubstr(s)) != 0; }
C4_ALWAYS_INLINE bool operator>= (c4::csubstr ss, std::string const& s) { return ss.compare(to_csubstr(s)) >= 0; }
C4_ALWAYS_INLINE bool operator>  (c4::csubstr ss, std::string const& s) { return ss.compare(to_csubstr(s)) >  0; }
C4_ALWAYS_INLINE bool operator<= (c4::csubstr ss, std::string const& s) { return ss.compare(to_csubstr(s)) <= 0; }
C4_ALWAYS_INLINE bool operator<  (c4::csubstr ss, std::string const& s) { return ss.compare(to_csubstr(s)) <  0; }

C4_ALWAYS_INLINE bool operator== (std::string const& s, c4::csubstr ss) { return ss.compare(to_csubstr(s)) == 0; }
C4_ALWAYS_INLINE bool operator!= (std::string const& s, c4::csubstr ss) { return ss.compare(to_csubstr(s)) != 0; }
C4_ALWAYS_INLINE bool operator>= (std::string const& s, c4::csubstr ss) { return ss.compare(to_csubstr(s)) <= 0; }
C4_ALWAYS_INLINE bool operator>  (std::string const& s, c4::csubstr ss) { return ss.compare(to_csubstr(s)) <  0; }
C4_ALWAYS_INLINE bool operator<= (std::string const& s, c4::csubstr ss) { return ss.compare(to_csubstr(s)) >= 0; }
C4_ALWAYS_INLINE bool operator<  (std::string const& s, c4::csubstr ss) { return ss.compare(to_csubstr(s)) >  0; }

//-----------------------------------------------------------------------------

/** copy an std::string to a writeable string view */
inline size_t to_chars(c4::substr buf, std::string const& s)
{
    C4_ASSERT(!buf.overlaps(to_csubstr(s)));
    size_t len = buf.len < s.size() ? buf.len : s.size();
    // calling memcpy with null strings is undefined behavior
    // and will wreak havoc in calling code's branches.
    // see https://github.com/biojppm/rapidyaml/pull/264#issuecomment-1262133637
    if(len)
    {
        C4_ASSERT(s.data() != nullptr);
        C4_ASSERT(buf.str != nullptr);
        memcpy(buf.str, s.data(), len);
    }
    return s.size(); // return the number of needed chars
}

/** copy a string view to an existing std::string */
inline bool from_chars(c4::csubstr buf, std::string * s)
{
    s->resize(buf.len);
    C4_ASSERT(!buf.overlaps(to_csubstr(*s)));
    // calling memcpy with null strings is undefined behavior
    // and will wreak havoc in calling code's branches.
    // see https://github.com/biojppm/rapidyaml/pull/264#issuecomment-1262133637
    if(buf.len)
    {
        C4_ASSERT(buf.str != nullptr);
        memcpy(&(*s)[0], buf.str, buf.len);
    }
    return true;
}

} // namespace c4

#endif // _C4_STD_STRING_HPP_


// (end https://github.com/biojppm/c4core/src/c4/std/string.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/std/vector.hpp
// https://github.com/biojppm/c4core/src/c4/std/vector.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_STD_VECTOR_HPP_
#define _C4_STD_VECTOR_HPP_

/** @file vector.hpp provides conversion and comparison facilities
 * from/between std::vector<char> to c4::substr and c4::csubstr.
 * @todo add to_span() and friends
 */

#ifndef C4CORE_SINGLE_HEADER
// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/substr.hpp
//#include "c4/substr.hpp"
#if !defined(C4_SUBSTR_HPP_) && !defined(_C4_SUBSTR_HPP_)
#error "amalgamate: file c4/substr.hpp must have been included at this point"
#endif /* C4_SUBSTR_HPP_ */

#endif

#include <vector>

namespace c4 {

//-----------------------------------------------------------------------------

/** get a substr (writeable string view) of an existing std::vector<char> */
template<class Alloc>
c4::substr to_substr(std::vector<char, Alloc> &vec)
{
    char *data = vec.empty() ? nullptr : vec.data(); // data() may or may not return a null pointer.
    return c4::substr(data, vec.size());
}

/** get a csubstr (read-only string) view of an existing std::vector<char> */
template<class Alloc>
c4::csubstr to_csubstr(std::vector<char, Alloc> const& vec)
{
    const char *data = vec.empty() ? nullptr : vec.data(); // data() may or may not return a null pointer.
    return c4::csubstr(data, vec.size());
}

//-----------------------------------------------------------------------------
// comparisons between substrings and std::vector<char>

template<class Alloc> C4_ALWAYS_INLINE bool operator!= (c4::csubstr ss, std::vector<char, Alloc> const& s) { return ss != to_csubstr(s); }
template<class Alloc> C4_ALWAYS_INLINE bool operator== (c4::csubstr ss, std::vector<char, Alloc> const& s) { return ss == to_csubstr(s); }
template<class Alloc> C4_ALWAYS_INLINE bool operator>= (c4::csubstr ss, std::vector<char, Alloc> const& s) { return ss >= to_csubstr(s); }
template<class Alloc> C4_ALWAYS_INLINE bool operator>  (c4::csubstr ss, std::vector<char, Alloc> const& s) { return ss >  to_csubstr(s); }
template<class Alloc> C4_ALWAYS_INLINE bool operator<= (c4::csubstr ss, std::vector<char, Alloc> const& s) { return ss <= to_csubstr(s); }
template<class Alloc> C4_ALWAYS_INLINE bool operator<  (c4::csubstr ss, std::vector<char, Alloc> const& s) { return ss <  to_csubstr(s); }

template<class Alloc> C4_ALWAYS_INLINE bool operator!= (std::vector<char, Alloc> const& s, c4::csubstr ss) { return ss != to_csubstr(s); }
template<class Alloc> C4_ALWAYS_INLINE bool operator== (std::vector<char, Alloc> const& s, c4::csubstr ss) { return ss == to_csubstr(s); }
template<class Alloc> C4_ALWAYS_INLINE bool operator>= (std::vector<char, Alloc> const& s, c4::csubstr ss) { return ss <= to_csubstr(s); }
template<class Alloc> C4_ALWAYS_INLINE bool operator>  (std::vector<char, Alloc> const& s, c4::csubstr ss) { return ss <  to_csubstr(s); }
template<class Alloc> C4_ALWAYS_INLINE bool operator<= (std::vector<char, Alloc> const& s, c4::csubstr ss) { return ss >= to_csubstr(s); }
template<class Alloc> C4_ALWAYS_INLINE bool operator<  (std::vector<char, Alloc> const& s, c4::csubstr ss) { return ss >  to_csubstr(s); }

//-----------------------------------------------------------------------------

/** copy a std::vector<char> to a writeable string view */
template<class Alloc>
inline size_t to_chars(c4::substr buf, std::vector<char, Alloc> const& s)
{
    C4_ASSERT(!buf.overlaps(to_csubstr(s)));
    size_t len = buf.len < s.size() ? buf.len : s.size();
    // calling memcpy with null strings is undefined behavior
    // and will wreak havoc in calling code's branches.
    // see https://github.com/biojppm/rapidyaml/pull/264#issuecomment-1262133637
    if(len > 0)
    {
        memcpy(buf.str, s.data(), len);
    }
    return s.size(); // return the number of needed chars
}

/** copy a string view to an existing std::vector<char> */
template<class Alloc>
inline bool from_chars(c4::csubstr buf, std::vector<char, Alloc> * s)
{
    s->resize(buf.len);
    C4_ASSERT(!buf.overlaps(to_csubstr(*s)));
    // calling memcpy with null strings is undefined behavior
    // and will wreak havoc in calling code's branches.
    // see https://github.com/biojppm/rapidyaml/pull/264#issuecomment-1262133637
    if(buf.len > 0)
    {
        memcpy(&(*s)[0], buf.str, buf.len);
    }
    return true;
}

} // namespace c4

#endif // _C4_STD_VECTOR_HPP_


// (end https://github.com/biojppm/c4core/src/c4/std/vector.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/std/tuple.hpp
// https://github.com/biojppm/c4core/src/c4/std/tuple.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_STD_TUPLE_HPP_
#define _C4_STD_TUPLE_HPP_

/** @file tuple.hpp */

#ifndef C4CORE_SINGLE_HEADER
// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/format.hpp
//#include "c4/format.hpp"
#if !defined(C4_FORMAT_HPP_) && !defined(_C4_FORMAT_HPP_)
#error "amalgamate: file c4/format.hpp must have been included at this point"
#endif /* C4_FORMAT_HPP_ */

#endif

#include <tuple>

/** this is a work in progress */
#undef C4_TUPLE_TO_CHARS

namespace c4 {

#ifdef C4_TUPLE_TO_CHARS
namespace detail {

template< size_t Curr, class... Types >
struct tuple_helper
{
    static size_t do_cat(substr buf, std::tuple< Types... > const& tp)
    {
        size_t num = to_chars(buf, std::get<Curr>(tp));
        buf = buf.len >= num ? buf.sub(num) : substr{};
        num += tuple_helper< Curr+1, Types... >::do_cat(buf, tp);
        return num;
    }

    static size_t do_uncat(csubstr buf, std::tuple< Types... > & tp)
    {
        size_t num = from_str_trim(buf, &std::get<Curr>(tp));
        if(num == csubstr::npos) return csubstr::npos;
        buf = buf.len >= num ? buf.sub(num) : substr{};
        num += tuple_helper< Curr+1, Types... >::do_uncat(buf, tp);
        return num;
    }

    template< class Sep >
    static size_t do_catsep_more(substr buf, Sep const& sep, std::tuple< Types... > const& tp)
    {
        size_t ret = to_chars(buf, sep), num = ret;
        buf  = buf.len >= ret ? buf.sub(ret) : substr{};
        ret  = to_chars(buf, std::get<Curr>(tp));
        num += ret;
        buf  = buf.len >= ret ? buf.sub(ret) : substr{};
        ret  = tuple_helper< Curr+1, Types... >::do_catsep_more(buf, sep, tp);
        num += ret;
        return num;
    }

    template< class Sep >
    static size_t do_uncatsep_more(csubstr buf, Sep & sep, std::tuple< Types... > & tp)
    {
        size_t ret = from_str_trim(buf, &sep), num = ret;
        if(ret == csubstr::npos) return csubstr::npos;
        buf  = buf.len >= ret ? buf.sub(ret) : substr{};
        ret  = from_str_trim(buf, &std::get<Curr>(tp));
        if(ret == csubstr::npos) return csubstr::npos;
        num += ret;
        buf  = buf.len >= ret ? buf.sub(ret) : substr{};
        ret  = tuple_helper< Curr+1, Types... >::do_uncatsep_more(buf, sep, tp);
        if(ret == csubstr::npos) return csubstr::npos;
        num += ret;
        return num;
    }

    static size_t do_format(substr buf, csubstr fmt, std::tuple< Types... > const& tp)
    {
        auto pos = fmt.find("{}");
        if(pos != csubstr::npos)
        {
            size_t num = to_chars(buf, fmt.sub(0, pos));
            size_t out = num;
            buf  = buf.len >= num ? buf.sub(num) : substr{};
            num  = to_chars(buf, std::get<Curr>(tp));
            out += num;
            buf  = buf.len >= num ? buf.sub(num) : substr{};
            num  = tuple_helper< Curr+1, Types... >::do_format(buf, fmt.sub(pos + 2), tp);
            out += num;
            return out;
        }
        else
        {
            return format(buf, fmt);
        }
    }

    static size_t do_unformat(csubstr buf, csubstr fmt, std::tuple< Types... > & tp)
    {
        auto pos = fmt.find("{}");
        if(pos != csubstr::npos)
        {
            size_t num = pos;
            size_t out = num;
            buf  = buf.len >= num ? buf.sub(num) : substr{};
            num  = from_str_trim(buf, &std::get<Curr>(tp));
            out += num;
            buf  = buf.len >= num ? buf.sub(num) : substr{};
            num  = tuple_helper< Curr+1, Types... >::do_unformat(buf, fmt.sub(pos + 2), tp);
            out += num;
            return out;
        }
        else
        {
            return tuple_helper< sizeof...(Types), Types... >::do_unformat(buf, fmt, tp);
        }
    }

};

/** @todo VS compilation fails for this class */
template< class... Types >
struct tuple_helper< sizeof...(Types), Types... >
{
    static size_t do_cat(substr /*buf*/, std::tuple<Types...> const& /*tp*/) { return 0; }
    static size_t do_uncat(csubstr /*buf*/, std::tuple<Types...> & /*tp*/) { return 0; }

    template< class Sep > static size_t do_catsep_more(substr /*buf*/, Sep const& /*sep*/, std::tuple<Types...> const& /*tp*/) { return 0; }
    template< class Sep > static size_t do_uncatsep_more(csubstr /*buf*/, Sep & /*sep*/, std::tuple<Types...> & /*tp*/) { return 0; }

    static size_t do_format(substr buf, csubstr fmt, std::tuple<Types...> const& /*tp*/)
    {
        return to_chars(buf, fmt);
    }

    static size_t do_unformat(csubstr buf, csubstr fmt, std::tuple<Types...> const& /*tp*/)
    {
        return 0;
    }
};

} // namespace detail

template< class... Types >
inline size_t cat(substr buf, std::tuple< Types... > const& tp)
{
    return detail::tuple_helper< 0, Types... >::do_cat(buf, tp);
}

template< class... Types >
inline size_t uncat(csubstr buf, std::tuple< Types... > & tp)
{
    return detail::tuple_helper< 0, Types... >::do_uncat(buf, tp);
}

template< class Sep, class... Types >
inline size_t catsep(substr buf, Sep const& sep, std::tuple< Types... > const& tp)
{
    size_t num = to_chars(buf, std::cref(std::get<0>(tp)));
    buf  = buf.len >= num ? buf.sub(num) : substr{};
    num += detail::tuple_helper< 1, Types... >::do_catsep_more(buf, sep, tp);
    return num;
}

template< class Sep, class... Types >
inline size_t uncatsep(csubstr buf, Sep & sep, std::tuple< Types... > & tp)
{
    size_t ret = from_str_trim(buf, &std::get<0>(tp)), num = ret;
    if(ret == csubstr::npos) return csubstr::npos;
    buf  = buf.len >= ret ? buf.sub(ret) : substr{};
    ret  = detail::tuple_helper< 1, Types... >::do_uncatsep_more(buf, sep, tp);
    if(ret == csubstr::npos) return csubstr::npos;
    num += ret;
    return num;
}

template< class... Types >
inline size_t format(substr buf, csubstr fmt, std::tuple< Types... > const& tp)
{
    return detail::tuple_helper< 0, Types... >::do_format(buf, fmt, tp);
}

template< class... Types >
inline size_t unformat(csubstr buf, csubstr fmt, std::tuple< Types... > & tp)
{
    return detail::tuple_helper< 0, Types... >::do_unformat(buf, fmt, tp);
}
#endif // C4_TUPLE_TO_CHARS

} // namespace c4

#endif /* _C4_STD_TUPLE_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/std/tuple.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/ext/rng/rng.hpp
// https://github.com/biojppm/c4core/src/c4/ext/rng/rng.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

/* Copyright (c) 2018 Arvid Gerstmann.
 *
 * https://arvid.io/2018/07/02/better-cxx-prng/
 *
 * This code is licensed under MIT license. */
#ifndef AG_RANDOM_H
#define AG_RANDOM_H

//included above:
//#include <stdint.h>
#include <random>


namespace c4 {
namespace rng {


class splitmix
{
public:
    using result_type = uint32_t;
    static constexpr result_type (min)() { return 0; }
    static constexpr result_type (max)() { return UINT32_MAX; }
    friend bool operator==(splitmix const &, splitmix const &);
    friend bool operator!=(splitmix const &, splitmix const &);

    splitmix() : m_seed(1) {}
    explicit splitmix(uint64_t s) : m_seed(s) {}
    explicit splitmix(std::random_device &rd)
    {
        seed(rd);
    }

    void seed(uint64_t s) { m_seed = s; }
    void seed(std::random_device &rd)
    {
        m_seed = uint64_t(rd()) << 31 | uint64_t(rd());
    }

    result_type operator()()
    {
        uint64_t z = (m_seed += UINT64_C(0x9E3779B97F4A7C15));
        z = (z ^ (z >> 30)) * UINT64_C(0xBF58476D1CE4E5B9);
        z = (z ^ (z >> 27)) * UINT64_C(0x94D049BB133111EB);
        return result_type((z ^ (z >> 31)) >> 31);
    }

    void discard(unsigned long long n)
    {
        for (unsigned long long i = 0; i < n; ++i)
            operator()();
    }

private:
    uint64_t m_seed;
};

inline bool operator==(splitmix const &lhs, splitmix const &rhs)
{
    return lhs.m_seed == rhs.m_seed;
}
inline bool operator!=(splitmix const &lhs, splitmix const &rhs)
{
    return lhs.m_seed != rhs.m_seed;
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

class xorshift
{
public:
    using result_type = uint32_t;
    static constexpr result_type (min)() { return 0; }
    static constexpr result_type (max)() { return UINT32_MAX; }
    friend bool operator==(xorshift const &, xorshift const &);
    friend bool operator!=(xorshift const &, xorshift const &);

    xorshift() : m_seed(0xc1f651c67c62c6e0ull) {}
    explicit xorshift(std::random_device &rd)
    {
        seed(rd);
    }

    void seed(uint64_t s) { m_seed = s; }
    void seed(std::random_device &rd)
    {
        m_seed = uint64_t(rd()) << 31 | uint64_t(rd());
    }

    result_type operator()()
    {
        uint64_t result = m_seed * 0xd989bcacc137dcd5ull;
        m_seed ^= m_seed >> 11;
        m_seed ^= m_seed << 31;
        m_seed ^= m_seed >> 18;
        return uint32_t(result >> 32ull);
    }

    void discard(unsigned long long n)
    {
        for (unsigned long long i = 0; i < n; ++i)
            operator()();
    }

private:
    uint64_t m_seed;
};

inline bool operator==(xorshift const &lhs, xorshift const &rhs)
{
    return lhs.m_seed == rhs.m_seed;
}
inline bool operator!=(xorshift const &lhs, xorshift const &rhs)
{
    return lhs.m_seed != rhs.m_seed;
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

class pcg
{
public:
    using result_type = uint32_t;
    static constexpr result_type (min)() { return 0; }
    static constexpr result_type (max)() { return UINT32_MAX; }
    friend bool operator==(pcg const &, pcg const &);
    friend bool operator!=(pcg const &, pcg const &);

    pcg()
        : m_state(0x853c49e6748fea9bULL)
        , m_inc(0xda3e39cb94b95bdbULL)
    {}
    explicit pcg(uint64_t s) { m_state = s; m_inc = m_state << 1; }
    explicit pcg(std::random_device &rd)
    {
        seed(rd);
    }

    void seed(uint64_t s) { m_state = s; }
    void seed(std::random_device &rd)
    {
        uint64_t s0 = uint64_t(rd()) << 31 | uint64_t(rd());
        uint64_t s1 = uint64_t(rd()) << 31 | uint64_t(rd());

        m_state = 0;
        m_inc = (s1 << 1) | 1;
        (void)operator()();
        m_state += s0;
        (void)operator()();
    }

    result_type operator()()
    {
        uint64_t oldstate = m_state;
        m_state = oldstate * 6364136223846793005ULL + m_inc;
        uint32_t xorshifted = uint32_t(((oldstate >> 18u) ^ oldstate) >> 27u);
        //int rot = oldstate >> 59u; // the original. error?
        int64_t rot = (int64_t)oldstate >> 59u; // error?
        return (xorshifted >> rot) | (xorshifted << ((uint64_t)(-rot) & 31));
    }

    void discard(unsigned long long n)
    {
        for (unsigned long long i = 0; i < n; ++i)
            operator()();
    }

private:
    uint64_t m_state;
    uint64_t m_inc;
};

inline bool operator==(pcg const &lhs, pcg const &rhs)
{
    return lhs.m_state == rhs.m_state
        && lhs.m_inc == rhs.m_inc;
}
inline bool operator!=(pcg const &lhs, pcg const &rhs)
{
    return lhs.m_state != rhs.m_state
        || lhs.m_inc != rhs.m_inc;
}

} // namespace rng
} // namespace c4

#endif /* AG_RANDOM_H */


// (end https://github.com/biojppm/c4core/src/c4/ext/rng/rng.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/ext/sg14/inplace_function.h
// https://github.com/biojppm/c4core/src/c4/ext/sg14/inplace_function.h
//--------------------------------------------------------------------------------
//********************************************************************************

/*
 * Boost Software License - Version 1.0 - August 17th, 2003
 *
 * Permission is hereby granted, free of charge, to any person or organization
 * obtaining a copy of the software and accompanying documentation covered by
 * this license (the "Software") to use, reproduce, display, distribute,
 * execute, and transmit the Software, and to prepare derivative works of the
 * Software, and to permit third-parties to whom the Software is furnished to
 * do so, all subject to the following:
 *
 * The copyright notices in the Software and this entire statement, including
 * the above license grant, this restriction and the following disclaimer,
 * must be included in all copies of the Software, in whole or in part, and
 * all derivative works of the Software, unless such copies or derivative
 * works are solely in the form of machine-executable object code generated by
 * a source language processor.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
 * SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
 * FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */
#ifndef _C4_EXT_SG14_INPLACE_FUNCTION_H_
#define _C4_EXT_SG14_INPLACE_FUNCTION_H_

//included above:
//#include <type_traits>
//included above:
//#include <utility>
#include <functional>

namespace stdext {

namespace inplace_function_detail {

static constexpr size_t InplaceFunctionDefaultCapacity = 32;

#if defined(__GLIBCXX__)  // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61458
template<size_t Cap>
union aligned_storage_helper {
    struct double1 { double a; };
    struct double4 { double a[4]; };
    template<class T> using maybe = typename std::conditional<(Cap >= sizeof(T)), T, char>::type;
    char real_data[Cap];
    maybe<int> a;
    maybe<long> b;
    maybe<long long> c;
    maybe<void*> d;
    maybe<void(*)()> e;
    maybe<double1> f;
    maybe<double4> g;
    maybe<long double> h;
};

template<size_t Cap, size_t Align = std::alignment_of<aligned_storage_helper<Cap>>::value>
struct aligned_storage {
    using type = typename std::aligned_storage<Cap, Align>::type;
};
#else
using std::aligned_storage;
#endif

template<typename T> struct wrapper
{
    using type = T;
};

template<typename R, typename... Args> struct vtable
{
    using storage_ptr_t = void*;

    using invoke_ptr_t = R(*)(storage_ptr_t, Args&&...);
    using process_ptr_t = void(*)(storage_ptr_t, storage_ptr_t);
    using destructor_ptr_t = void(*)(storage_ptr_t);

    const invoke_ptr_t invoke_ptr;
    const process_ptr_t copy_ptr;
    const process_ptr_t move_ptr;
    const destructor_ptr_t destructor_ptr;

    explicit constexpr vtable() noexcept :
        invoke_ptr{ [](storage_ptr_t, Args&&...) -> R
            { throw std::bad_function_call(); }
        },
        copy_ptr{ [](storage_ptr_t, storage_ptr_t) noexcept -> void {} },
        move_ptr{ [](storage_ptr_t, storage_ptr_t) noexcept -> void {} },
        destructor_ptr{ [](storage_ptr_t) noexcept -> void {} }
    {}

    template<typename C> explicit constexpr vtable(wrapper<C>) noexcept :
        invoke_ptr{ [](storage_ptr_t storage_ptr, Args&&... args)
            noexcept(noexcept(std::declval<C>()(args...))) -> R
            { return (*static_cast<C*>(storage_ptr))(
                std::forward<Args>(args)...
            ); }
        },
        copy_ptr{ [](storage_ptr_t dst_ptr, storage_ptr_t src_ptr)
            noexcept(std::is_nothrow_copy_constructible<C>::value) -> void
            { new (dst_ptr) C{ (*static_cast<C*>(src_ptr)) }; }
        },
        move_ptr{ [](storage_ptr_t dst_ptr, storage_ptr_t src_ptr)
            noexcept(std::is_nothrow_move_constructible<C>::value) -> void
            { new (dst_ptr) C{ std::move(*static_cast<C*>(src_ptr)) }; }
        },
        destructor_ptr{ [](storage_ptr_t storage_ptr)
            noexcept -> void
            { static_cast<C*>(storage_ptr)->~C(); }
        }
    {}

    vtable(const vtable&) = delete;
    vtable(vtable&&) = delete;

    vtable& operator= (const vtable&) = delete;
    vtable& operator= (vtable&&) = delete;

    ~vtable() = default;
};

template<size_t DstCap, size_t DstAlign, size_t SrcCap, size_t SrcAlign>
struct is_valid_inplace_dst : std::true_type
{
    static_assert(DstCap >= SrcCap,
        "Can't squeeze larger inplace_function into a smaller one"
    );

    static_assert(DstAlign % SrcAlign == 0,
        "Incompatible inplace_function alignments"
    );
};

} // namespace inplace_function_detail

template<
    typename Signature,
    size_t Capacity = inplace_function_detail::InplaceFunctionDefaultCapacity,
    size_t Alignment = std::alignment_of<typename inplace_function_detail::aligned_storage<Capacity>::type>::value
>
class inplace_function; // unspecified

template<
    typename R,
    typename... Args,
    size_t Capacity,
    size_t Alignment
>
class inplace_function<R(Args...), Capacity, Alignment>
{
    static const constexpr inplace_function_detail::vtable<R, Args...> empty_vtable{};
public:
    using capacity = std::integral_constant<size_t, Capacity>;
    using alignment = std::integral_constant<size_t, Alignment>;

    using storage_t = typename inplace_function_detail::aligned_storage<Capacity, Alignment>::type;
    using vtable_t = inplace_function_detail::vtable<R, Args...>;
    using vtable_ptr_t = const vtable_t*;

    template <typename, size_t, size_t>	friend class inplace_function;

    inplace_function() noexcept :
        vtable_ptr_{std::addressof(empty_vtable)}
    {}

    template<
        typename T,
        typename C = typename std::decay<T>::type,
        typename = typename std::enable_if<
            !(std::is_same<C, inplace_function>::value
            || std::is_convertible<C, inplace_function>::value)
        >::type
    >
    inplace_function(T&& closure)
    {
#if __cplusplus >= 201703L
        static_assert(std::is_invocable_r<R, C, Args...>::value,
            "inplace_function cannot be constructed from non-callable type"
        );
#endif
        static_assert(std::is_copy_constructible<C>::value,
            "inplace_function cannot be constructed from non-copyable type"
        );

        static_assert(sizeof(C) <= Capacity,
            "inplace_function cannot be constructed from object with this (large) size"
        );

        static_assert(Alignment % std::alignment_of<C>::value == 0,
            "inplace_function cannot be constructed from object with this (large) alignment"
        );

        static const vtable_t vt{inplace_function_detail::wrapper<C>{}};
        vtable_ptr_ = std::addressof(vt);

        new (std::addressof(storage_)) C{std::forward<T>(closure)};
    }

    inplace_function(std::nullptr_t) noexcept :
        vtable_ptr_{std::addressof(empty_vtable)}
    {}

    inplace_function(const inplace_function& other) :
        vtable_ptr_{other.vtable_ptr_}
    {
        vtable_ptr_->copy_ptr(
            std::addressof(storage_),
            std::addressof(other.storage_)
        );
    }

    inplace_function(inplace_function&& other) :
        vtable_ptr_{other.vtable_ptr_}
    {
        vtable_ptr_->move_ptr(
            std::addressof(storage_),
            std::addressof(other.storage_)
        );
    }

    inplace_function& operator= (std::nullptr_t) noexcept
    {
        vtable_ptr_->destructor_ptr(std::addressof(storage_));
        vtable_ptr_ = std::addressof(empty_vtable);
        return *this;
    }

    inplace_function& operator= (const inplace_function& other)
    {
        if(this != std::addressof(other))
        {
            vtable_ptr_->destructor_ptr(std::addressof(storage_));

            vtable_ptr_ = other.vtable_ptr_;
            vtable_ptr_->copy_ptr(
                std::addressof(storage_),
                std::addressof(other.storage_)
            );
        }
        return *this;
    }

    inplace_function& operator= (inplace_function&& other)
    {
        if(this != std::addressof(other))
        {
            vtable_ptr_->destructor_ptr(std::addressof(storage_));

            vtable_ptr_ = other.vtable_ptr_;
            vtable_ptr_->move_ptr(
                std::addressof(storage_),
                std::addressof(other.storage_)
            );
        }
        return *this;
    }

    ~inplace_function()
    {
        vtable_ptr_->destructor_ptr(std::addressof(storage_));
    }

    R operator() (Args... args) const
    {
        return vtable_ptr_->invoke_ptr(
            std::addressof(storage_),
            std::forward<Args>(args)...
        );
    }

    constexpr bool operator== (std::nullptr_t) const noexcept
    {
        return !operator bool();
    }

    constexpr bool operator!= (std::nullptr_t) const noexcept
    {
        return operator bool();
    }

    explicit constexpr operator bool() const noexcept
    {
        return vtable_ptr_ != std::addressof(empty_vtable);
    }

    template<size_t Cap, size_t Align>
    operator inplace_function<R(Args...), Cap, Align>() const&
    {
        static_assert(inplace_function_detail::is_valid_inplace_dst<
            Cap, Align, Capacity, Alignment
        >::value, "conversion not allowed");

        return {vtable_ptr_, vtable_ptr_->copy_ptr, std::addressof(storage_)};
    }

    template<size_t Cap, size_t Align>
    operator inplace_function<R(Args...), Cap, Align>() &&
    {
        static_assert(inplace_function_detail::is_valid_inplace_dst<
            Cap, Align, Capacity, Alignment
        >::value, "conversion not allowed");

        return {vtable_ptr_, vtable_ptr_->move_ptr, std::addressof(storage_)};
    }

    void swap(inplace_function& other)
    {
        if (this == std::addressof(other)) return;

        storage_t tmp;
        vtable_ptr_->move_ptr(
            std::addressof(tmp),
            std::addressof(storage_)
        );
        vtable_ptr_->destructor_ptr(std::addressof(storage_));

        other.vtable_ptr_->move_ptr(
            std::addressof(storage_),
            std::addressof(other.storage_)
        );
        other.vtable_ptr_->destructor_ptr(std::addressof(other.storage_));

        vtable_ptr_->move_ptr(
            std::addressof(other.storage_),
            std::addressof(tmp)
        );
        vtable_ptr_->destructor_ptr(std::addressof(tmp));

        std::swap(vtable_ptr_, other.vtable_ptr_);
    }

private:
    vtable_ptr_t vtable_ptr_;
    mutable storage_t storage_;

    inplace_function(
        vtable_ptr_t vtable_ptr,
        typename vtable_t::process_ptr_t process_ptr,
        typename vtable_t::storage_ptr_t storage_ptr
    ) : vtable_ptr_{vtable_ptr}
    {
        process_ptr(std::addressof(storage_), storage_ptr);
    }
};

} // namespace stdext

#endif /* _C4_EXT_SG14_INPLACE_FUNCTION_H_ */


// (end https://github.com/biojppm/c4core/src/c4/ext/sg14/inplace_function.h)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/language.cpp
// https://github.com/biojppm/c4core/src/c4/language.cpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifdef C4CORE_SINGLE_HDR_DEFINE_NOW
// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/language.hpp
//#include "c4/language.hpp"
#if !defined(C4_LANGUAGE_HPP_) && !defined(_C4_LANGUAGE_HPP_)
#error "amalgamate: file c4/language.hpp must have been included at this point"
#endif /* C4_LANGUAGE_HPP_ */


namespace c4 {
namespace detail {

#ifndef __GNUC__
void use_char_pointer(char const volatile* v)
{
    C4_UNUSED(v);
}
#else
void foo() {} // to avoid empty file warning from the linker
#endif

} // namespace detail
} // namespace c4

#endif /* C4CORE_SINGLE_HDR_DEFINE_NOW */


// (end https://github.com/biojppm/c4core/src/c4/language.cpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/format.cpp
// https://github.com/biojppm/c4core/src/c4/format.cpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifdef C4CORE_SINGLE_HDR_DEFINE_NOW
// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/format.hpp
//#include "c4/format.hpp"
#if !defined(C4_FORMAT_HPP_) && !defined(_C4_FORMAT_HPP_)
#error "amalgamate: file c4/format.hpp must have been included at this point"
#endif /* C4_FORMAT_HPP_ */


//included above:
//#include <memory> // for std::align

#ifdef __clang__
#   pragma clang diagnostic push
#   pragma clang diagnostic ignored "-Wformat-nonliteral"
#elif defined(__GNUC__)
#   pragma GCC diagnostic push
#   pragma GCC diagnostic ignored "-Wformat-nonliteral"
#endif

namespace c4 {


size_t to_chars(substr buf, fmt::const_raw_wrapper r)
{
    void * vptr = buf.str;
    size_t space = buf.len;
    auto ptr = (decltype(buf.str)) std::align(r.alignment, r.len, vptr, space);
    if(ptr == nullptr)
    {
        // if it was not possible to align, return a conservative estimate
        // of the required space
        return r.alignment + r.len;
    }
    C4_CHECK(ptr >= buf.begin() && ptr <= buf.end());
    size_t sz = static_cast<size_t>(ptr - buf.str) + r.len;
    if(sz <= buf.len)
    {
        memcpy(ptr, r.buf, r.len);
    }
    return sz;
}


bool from_chars(csubstr buf, fmt::raw_wrapper *r)
{
    void * vptr = (void*)buf.str;
    size_t space = buf.len;
    auto ptr = (decltype(buf.str)) std::align(r->alignment, r->len, vptr, space);
    C4_CHECK(ptr != nullptr);
    C4_CHECK(ptr >= buf.begin() && ptr <= buf.end());
    //size_t dim = (ptr - buf.str) + r->len;
    memcpy(r->buf, ptr, r->len);
    return true;
}


} // namespace c4

#ifdef __clang__
#   pragma clang diagnostic pop
#elif defined(__GNUC__)
#   pragma GCC diagnostic pop
#endif

#endif /* C4CORE_SINGLE_HDR_DEFINE_NOW */


// (end https://github.com/biojppm/c4core/src/c4/format.cpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/memory_util.cpp
// https://github.com/biojppm/c4core/src/c4/memory_util.cpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifdef C4CORE_SINGLE_HDR_DEFINE_NOW
// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/memory_util.hpp
//#include "c4/memory_util.hpp"
#if !defined(C4_MEMORY_UTIL_HPP_) && !defined(_C4_MEMORY_UTIL_HPP_)
#error "amalgamate: file c4/memory_util.hpp must have been included at this point"
#endif /* C4_MEMORY_UTIL_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/error.hpp
//#include "c4/error.hpp"
#if !defined(C4_ERROR_HPP_) && !defined(_C4_ERROR_HPP_)
#error "amalgamate: file c4/error.hpp must have been included at this point"
#endif /* C4_ERROR_HPP_ */


namespace c4 {

/** Fills 'dest' with the first 'pattern_size' bytes at 'pattern', 'num_times'. */
void mem_repeat(void* dest, void const* pattern, size_t pattern_size, size_t num_times)
{
    if(C4_UNLIKELY(num_times == 0))
        return;
    C4_ASSERT( ! mem_overlaps(dest, pattern, num_times*pattern_size, pattern_size));
    char *begin = (char*)dest;
    char *end   = begin + num_times * pattern_size;
    // copy the pattern once
    ::memcpy(begin, pattern, pattern_size);
    // now copy from dest to itself, doubling up every time
    size_t n = pattern_size;
    while(begin + 2*n < end)
    {
        ::memcpy(begin + n, begin, n);
        n <<= 1; // double n
    }
    // copy the missing part
    if(begin + n < end)
    {
        ::memcpy(begin + n, begin, static_cast<size_t>(end - (begin + n)));
    }
}

} // namespace c4

#endif /* C4CORE_SINGLE_HDR_DEFINE_NOW */


// (end https://github.com/biojppm/c4core/src/c4/memory_util.cpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/char_traits.cpp
// https://github.com/biojppm/c4core/src/c4/char_traits.cpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifdef C4CORE_SINGLE_HDR_DEFINE_NOW
// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/char_traits.hpp
//#include "c4/char_traits.hpp"
#if !defined(C4_CHAR_TRAITS_HPP_) && !defined(_C4_CHAR_TRAITS_HPP_)
#error "amalgamate: file c4/char_traits.hpp must have been included at this point"
#endif /* C4_CHAR_TRAITS_HPP_ */


namespace c4 {

constexpr const char char_traits< char >::whitespace_chars[];
constexpr const size_t char_traits< char >::num_whitespace_chars;
constexpr const wchar_t char_traits< wchar_t >::whitespace_chars[];
constexpr const size_t char_traits< wchar_t >::num_whitespace_chars;

} // namespace c4

#endif /* C4CORE_SINGLE_HDR_DEFINE_NOW */


// (end https://github.com/biojppm/c4core/src/c4/char_traits.cpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/memory_resource.cpp
// https://github.com/biojppm/c4core/src/c4/memory_resource.cpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifdef C4CORE_SINGLE_HDR_DEFINE_NOW
// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/memory_resource.hpp
//#include "c4/memory_resource.hpp"
#if !defined(C4_MEMORY_RESOURCE_HPP_) && !defined(_C4_MEMORY_RESOURCE_HPP_)
#error "amalgamate: file c4/memory_resource.hpp must have been included at this point"
#endif /* C4_MEMORY_RESOURCE_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/memory_util.hpp
//#include "c4/memory_util.hpp"
#if !defined(C4_MEMORY_UTIL_HPP_) && !defined(_C4_MEMORY_UTIL_HPP_)
#error "amalgamate: file c4/memory_util.hpp must have been included at this point"
#endif /* C4_MEMORY_UTIL_HPP_ */


//included above:
//#include <stdlib.h>
//included above:
//#include <string.h>
#if defined(C4_POSIX) || defined(C4_IOS) || defined(C4_MACOS) || defined(C4_ARM)
#   include <errno.h>
#endif
#if defined(C4_ARM)
#   include <malloc.h>
#endif

//included above:
//#include <memory>

namespace c4 {

namespace detail {


#ifdef C4_NO_ALLOC_DEFAULTS
aalloc_pfn s_aalloc = nullptr;
free_pfn s_afree = nullptr;
arealloc_pfn s_arealloc = nullptr;
#else


void afree_impl(void *ptr)
{
#if defined(C4_WIN) || defined(C4_XBOX)
    ::_aligned_free(ptr);
#else
    ::free(ptr);
#endif
}


void* aalloc_impl(size_t size, size_t alignment)
{
    void *mem;
#if defined(C4_WIN) || defined(C4_XBOX)
    mem = ::_aligned_malloc(size, alignment);
    C4_CHECK(mem != nullptr || size == 0);
#elif defined(C4_ARM)
    // https://stackoverflow.com/questions/53614538/undefined-reference-to-posix-memalign-in-arm-gcc
    // https://electronics.stackexchange.com/questions/467382/e2-studio-undefined-reference-to-posix-memalign/467753
    mem = memalign(alignment, size);
    C4_CHECK(mem != nullptr || size == 0);
#elif defined(C4_POSIX) || defined(C4_IOS) || defined(C4_MACOS)
    // NOTE: alignment needs to be sized in multiples of sizeof(void*)
    size_t amult = alignment;
    if(C4_UNLIKELY(alignment < sizeof(void*)))
    {
        amult = sizeof(void*);
    }
    int ret = ::posix_memalign(&mem, amult, size);
    if(C4_UNLIKELY(ret))
    {
        if(ret == EINVAL)
        {
            C4_ERROR("The alignment argument %zu was not a power of two, "
                     "or was not a multiple of sizeof(void*)", alignment);
        }
        else if(ret == ENOMEM)
        {
            C4_ERROR("There was insufficient memory to fulfill the "
                     "allocation request of %zu bytes (alignment=%lu)", size, size);
        }
        return nullptr;
    }
#else
    C4_NOT_IMPLEMENTED_MSG("need to implement an aligned allocation for this platform");
#endif
    C4_ASSERT_MSG((uintptr_t(mem) & (alignment-1)) == 0, "address %p is not aligned to %zu boundary", mem, alignment);
    return mem;
}


void* arealloc_impl(void* ptr, size_t oldsz, size_t newsz, size_t alignment)
{
    /** @todo make this more efficient
     * @see https://stackoverflow.com/questions/9078259/does-realloc-keep-the-memory-alignment-of-posix-memalign
     * @see look for qReallocAligned() in http://code.qt.io/cgit/qt/qtbase.git/tree/src/corelib/global/qmalloc.cpp
     */
    void *tmp = aalloc(newsz, alignment);
    size_t min = newsz < oldsz ? newsz : oldsz;
    if(mem_overlaps(ptr, tmp, oldsz, newsz))
    {
        ::memmove(tmp, ptr, min);
    }
    else
    {
        ::memcpy(tmp, ptr, min);
    }
    afree(ptr);
    return tmp;
}

aalloc_pfn s_aalloc = aalloc_impl;
afree_pfn s_afree = afree_impl;
arealloc_pfn s_arealloc = arealloc_impl;

#endif // C4_NO_ALLOC_DEFAULTS

} // namespace detail


aalloc_pfn get_aalloc()
{
    return detail::s_aalloc;
}
void set_aalloc(aalloc_pfn fn)
{
    detail::s_aalloc = fn;
}

afree_pfn get_afree()
{
    return detail::s_afree;
}
void set_afree(afree_pfn fn)
{
    detail::s_afree = fn;
}

arealloc_pfn get_arealloc()
{
    return detail::s_arealloc;
}
void set_arealloc(arealloc_pfn fn)
{
    detail::s_arealloc = fn;
}


void* aalloc(size_t sz, size_t alignment)
{
    C4_ASSERT_MSG(c4::get_aalloc() != nullptr, "did you forget to call set_aalloc()?");
    auto fn = c4::get_aalloc();
    void* ptr = fn(sz, alignment);
    return ptr;
}

void afree(void* ptr)
{
    C4_ASSERT_MSG(c4::get_afree() != nullptr, "did you forget to call set_afree()?");
    auto fn = c4::get_afree();
    fn(ptr);
}

void* arealloc(void *ptr, size_t oldsz, size_t newsz, size_t alignment)
{
    C4_ASSERT_MSG(c4::get_arealloc() != nullptr, "did you forget to call set_arealloc()?");
    auto fn = c4::get_arealloc();
    void* nptr = fn(ptr, oldsz, newsz, alignment);
    return nptr;
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

void detail::_MemoryResourceSingleChunk::release()
{
    if(m_mem && m_owner)
    {
        impl_type::deallocate(m_mem, m_size);
    }
    m_mem = nullptr;
    m_size = 0;
    m_owner = false;
    m_pos = 0;
}

void detail::_MemoryResourceSingleChunk::acquire(size_t sz)
{
    clear();
    m_owner = true;
    m_mem = (char*) impl_type::allocate(sz, alignof(max_align_t));
    m_size = sz;
    m_pos = 0;
}

void detail::_MemoryResourceSingleChunk::acquire(void *mem, size_t sz)
{
    clear();
    m_owner = false;
    m_mem = (char*) mem;
    m_size = sz;
    m_pos = 0;
}

//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

void* MemoryResourceLinear::do_allocate(size_t sz, size_t alignment, void *hint)
{
    C4_UNUSED(hint);
    if(sz == 0) return nullptr;
    // make sure there's enough room to allocate
    if(m_pos + sz > m_size)
    {
        C4_ERROR("out of memory");
        return nullptr;
    }
    void *mem = m_mem + m_pos;
    size_t space = m_size - m_pos;
    if(std::align(alignment, sz, mem, space))
    {
        C4_ASSERT(m_pos <= m_size);
        C4_ASSERT(m_size - m_pos >= space);
        m_pos += (m_size - m_pos) - space;
        m_pos += sz;
        C4_ASSERT(m_pos <= m_size);
    }
    else
    {
        C4_ERROR("could not align memory");
        mem = nullptr;
    }
    return mem;
}

void MemoryResourceLinear::do_deallocate(void* ptr, size_t sz, size_t alignment)
{
    C4_UNUSED(ptr);
    C4_UNUSED(sz);
    C4_UNUSED(alignment);
    // nothing to do!!
}

void* MemoryResourceLinear::do_reallocate(void* ptr, size_t oldsz, size_t newsz, size_t alignment)
{
    if(newsz == oldsz) return ptr;
    // is ptr the most recently allocated (MRA) block?
    char *cptr = (char*)ptr;
    bool same_pos = (m_mem + m_pos == cptr + oldsz);
    // no need to get more memory when shrinking
    if(newsz < oldsz)
    {
        // if this is the MRA, we can safely shrink the position
        if(same_pos)
        {
            m_pos -= oldsz - newsz;
        }
        return ptr;
    }
    // we're growing the block, and it fits in size
    else if(same_pos && cptr + newsz <= m_mem + m_size)
    {
        // if this is the MRA, we can safely shrink the position
        m_pos += newsz - oldsz;
        return ptr;
    }
    // we're growing the block or it doesn't fit -
    // delegate any of these situations to do_deallocate()
    return do_allocate(newsz, alignment, ptr);
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** @todo add a free list allocator. A good candidate because of its
 * small size is TLSF.
 *
 * @see https://github.com/mattconte/tlsf
 *
 * Comparisons:
 *
 * @see https://www.researchgate.net/publication/262375150_A_Comparative_Study_on_Memory_Allocators_in_Multicore_and_Multithreaded_Applications_-_SBESC_2011_-_Presentation_Slides
 * @see http://webkit.sed.hu/blog/20100324/war-allocators-tlsf-action
 * @see https://github.com/emeryberger/Malloc-Implementations/tree/master/allocators
 *
 * */

} // namespace c4


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

#ifdef C4_REDEFINE_CPPNEW
#include <new>
void* operator new(size_t size)
{
    auto *mr = ::c4::get_memory_resource();
    return mr->allocate(size);
}
void operator delete(void *p) noexcept
{
    C4_NEVER_REACH();
}
void operator delete(void *p, size_t size)
{
    auto *mr = ::c4::get_memory_resource();
    mr->deallocate(p, size);
}
void* operator new[](size_t size)
{
    return operator new(size);
}
void operator delete[](void *p) noexcept
{
    operator delete(p);
}
void operator delete[](void *p, size_t size)
{
    operator delete(p, size);
}
void* operator new(size_t size, std::nothrow_t)
{
    return operator new(size);
}
void operator delete(void *p, std::nothrow_t)
{
    operator delete(p);
}
void operator delete(void *p, size_t size, std::nothrow_t)
{
    operator delete(p, size);
}
void* operator new[](size_t size, std::nothrow_t)
{
    return operator new(size);
}
void operator delete[](void *p, std::nothrow_t)
{
    operator delete(p);
}
void operator delete[](void *p, size_t, std::nothrow_t)
{
    operator delete(p, size);
}
#endif // C4_REDEFINE_CPPNEW

#endif /* C4CORE_SINGLE_HDR_DEFINE_NOW */


// (end https://github.com/biojppm/c4core/src/c4/memory_resource.cpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/utf.cpp
// https://github.com/biojppm/c4core/src/c4/utf.cpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifdef C4CORE_SINGLE_HDR_DEFINE_NOW
// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/utf.hpp
//#include "c4/utf.hpp"
#if !defined(C4_UTF_HPP_) && !defined(_C4_UTF_HPP_)
#error "amalgamate: file c4/utf.hpp must have been included at this point"
#endif /* C4_UTF_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/charconv.hpp
//#include "c4/charconv.hpp"
#if !defined(C4_CHARCONV_HPP_) && !defined(_C4_CHARCONV_HPP_)
#error "amalgamate: file c4/charconv.hpp must have been included at this point"
#endif /* C4_CHARCONV_HPP_ */


namespace c4 {

size_t decode_code_point(uint8_t *C4_RESTRICT buf, size_t buflen, const uint32_t code)
{
    C4_UNUSED(buflen);
    C4_ASSERT(buflen >= 4);
    if (code <= UINT32_C(0x7f))
    {
        buf[0] = (uint8_t)code;
        return 1u;
    }
    else if(code <= UINT32_C(0x7ff))
    {
        buf[0] = (uint8_t)(UINT32_C(0xc0) | (code >> 6));             /* 110xxxxx */
        buf[1] = (uint8_t)(UINT32_C(0x80) | (code & UINT32_C(0x3f))); /* 10xxxxxx */
        return 2u;
    }
    else if(code <= UINT32_C(0xffff))
    {
        buf[0] = (uint8_t)(UINT32_C(0xe0) | ((code >> 12)));                  /* 1110xxxx */
        buf[1] = (uint8_t)(UINT32_C(0x80) | ((code >>  6) & UINT32_C(0x3f))); /* 10xxxxxx */
        buf[2] = (uint8_t)(UINT32_C(0x80) | ((code      ) & UINT32_C(0x3f))); /* 10xxxxxx */
        return 3u;
    }
    else if(code <= UINT32_C(0x10ffff))
    {
        buf[0] = (uint8_t)(UINT32_C(0xf0) | ((code >> 18)));                  /* 11110xxx */
        buf[1] = (uint8_t)(UINT32_C(0x80) | ((code >> 12) & UINT32_C(0x3f))); /* 10xxxxxx */
        buf[2] = (uint8_t)(UINT32_C(0x80) | ((code >>  6) & UINT32_C(0x3f))); /* 10xxxxxx */
        buf[3] = (uint8_t)(UINT32_C(0x80) | ((code      ) & UINT32_C(0x3f))); /* 10xxxxxx */
        return 4u;
    }
    return 0;
}

substr decode_code_point(substr out, csubstr code_point)
{
    C4_ASSERT(out.len >= 4);
    C4_ASSERT(!code_point.begins_with("U+"));
    C4_ASSERT(!code_point.begins_with("\\x"));
    C4_ASSERT(!code_point.begins_with("\\u"));
    C4_ASSERT(!code_point.begins_with("\\U"));
    C4_ASSERT(!code_point.begins_with('0'));
    C4_ASSERT(code_point.len <= 8);
    C4_ASSERT(code_point.len > 0);
    uint32_t code_point_val;
    C4_CHECK(read_hex(code_point, &code_point_val));
    size_t ret = decode_code_point((uint8_t*)out.str, out.len, code_point_val);
    C4_ASSERT(ret <= 4);
    return out.first(ret);
}

} // namespace c4

#endif /* C4CORE_SINGLE_HDR_DEFINE_NOW */


// (end https://github.com/biojppm/c4core/src/c4/utf.cpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/base64.cpp
// https://github.com/biojppm/c4core/src/c4/base64.cpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifdef C4CORE_SINGLE_HDR_DEFINE_NOW
// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/base64.hpp
//#include "c4/base64.hpp"
#if !defined(C4_BASE64_HPP_) && !defined(_C4_BASE64_HPP_)
#error "amalgamate: file c4/base64.hpp must have been included at this point"
#endif /* C4_BASE64_HPP_ */


#ifdef __clang__
#   pragma clang diagnostic push
#   pragma clang diagnostic ignored "-Wchar-subscripts" // array subscript is of type 'char'
#elif defined(__GNUC__)
#   pragma GCC diagnostic push
#   pragma GCC diagnostic ignored "-Wchar-subscripts"
#   pragma GCC diagnostic ignored "-Wtype-limits"
#endif

namespace c4 {

namespace detail {

constexpr static const char base64_sextet_to_char_[64] = {
    /* 0/ 65*/ 'A', /* 1/ 66*/ 'B', /* 2/ 67*/ 'C', /* 3/ 68*/ 'D',
    /* 4/ 69*/ 'E', /* 5/ 70*/ 'F', /* 6/ 71*/ 'G', /* 7/ 72*/ 'H',
    /* 8/ 73*/ 'I', /* 9/ 74*/ 'J', /*10/ 75*/ 'K', /*11/ 74*/ 'L',
    /*12/ 77*/ 'M', /*13/ 78*/ 'N', /*14/ 79*/ 'O', /*15/ 78*/ 'P',
    /*16/ 81*/ 'Q', /*17/ 82*/ 'R', /*18/ 83*/ 'S', /*19/ 82*/ 'T',
    /*20/ 85*/ 'U', /*21/ 86*/ 'V', /*22/ 87*/ 'W', /*23/ 88*/ 'X',
    /*24/ 89*/ 'Y', /*25/ 90*/ 'Z', /*26/ 97*/ 'a', /*27/ 98*/ 'b',
    /*28/ 99*/ 'c', /*29/100*/ 'd', /*30/101*/ 'e', /*31/102*/ 'f',
    /*32/103*/ 'g', /*33/104*/ 'h', /*34/105*/ 'i', /*35/106*/ 'j',
    /*36/107*/ 'k', /*37/108*/ 'l', /*38/109*/ 'm', /*39/110*/ 'n',
    /*40/111*/ 'o', /*41/112*/ 'p', /*42/113*/ 'q', /*43/114*/ 'r',
    /*44/115*/ 's', /*45/116*/ 't', /*46/117*/ 'u', /*47/118*/ 'v',
    /*48/119*/ 'w', /*49/120*/ 'x', /*50/121*/ 'y', /*51/122*/ 'z',
    /*52/ 48*/ '0', /*53/ 49*/ '1', /*54/ 50*/ '2', /*55/ 51*/ '3',
    /*56/ 52*/ '4', /*57/ 53*/ '5', /*58/ 54*/ '6', /*59/ 55*/ '7',
    /*60/ 56*/ '8', /*61/ 57*/ '9', /*62/ 43*/ '+', /*63/ 47*/ '/',
};

// https://www.cs.cmu.edu/~pattis/15-1XX/common/handouts/ascii.html
constexpr static const char base64_char_to_sextet_[128] = {
    #define __ char(-1) // undefined below
    /*  0 NUL*/ __, /*  1 SOH*/ __, /*  2 STX*/ __, /*  3 ETX*/ __,
    /*  4 EOT*/ __, /*  5 ENQ*/ __, /*  6 ACK*/ __, /*  7 BEL*/ __,
    /*  8 BS */ __, /*  9 TAB*/ __, /* 10 LF */ __, /* 11 VT */ __,
    /* 12 FF */ __, /* 13 CR */ __, /* 14 SO */ __, /* 15 SI */ __,
    /* 16 DLE*/ __, /* 17 DC1*/ __, /* 18 DC2*/ __, /* 19 DC3*/ __,
    /* 20 DC4*/ __, /* 21 NAK*/ __, /* 22 SYN*/ __, /* 23 ETB*/ __,
    /* 24 CAN*/ __, /* 25 EM */ __, /* 26 SUB*/ __, /* 27 ESC*/ __,
    /* 28 FS */ __, /* 29 GS */ __, /* 30 RS */ __, /* 31 US */ __,
    /* 32 SPC*/ __, /* 33 !  */ __, /* 34 "  */ __, /* 35 #  */ __,
    /* 36 $  */ __, /* 37 %  */ __, /* 38 &  */ __, /* 39 '  */ __,
    /* 40 (  */ __, /* 41 )  */ __, /* 42 *  */ __, /* 43 +  */ 62,
    /* 44 ,  */ __, /* 45 -  */ __, /* 46 .  */ __, /* 47 /  */ 63,
    /* 48 0  */ 52, /* 49 1  */ 53, /* 50 2  */ 54, /* 51 3  */ 55,
    /* 52 4  */ 56, /* 53 5  */ 57, /* 54 6  */ 58, /* 55 7  */ 59,
    /* 56 8  */ 60, /* 57 9  */ 61, /* 58 :  */ __, /* 59 ;  */ __,
    /* 60 <  */ __, /* 61 =  */ __, /* 62 >  */ __, /* 63 ?  */ __,
    /* 64 @  */ __, /* 65 A  */  0, /* 66 B  */  1, /* 67 C  */  2,
    /* 68 D  */  3, /* 69 E  */  4, /* 70 F  */  5, /* 71 G  */  6,
    /* 72 H  */  7, /* 73 I  */  8, /* 74 J  */  9, /* 75 K  */ 10,
    /* 76 L  */ 11, /* 77 M  */ 12, /* 78 N  */ 13, /* 79 O  */ 14,
    /* 80 P  */ 15, /* 81 Q  */ 16, /* 82 R  */ 17, /* 83 S  */ 18,
    /* 84 T  */ 19, /* 85 U  */ 20, /* 86 V  */ 21, /* 87 W  */ 22,
    /* 88 X  */ 23, /* 89 Y  */ 24, /* 90 Z  */ 25, /* 91 [  */ __,
    /* 92 \  */ __, /* 93 ]  */ __, /* 94 ^  */ __, /* 95 _  */ __,
    /* 96 `  */ __, /* 97 a  */ 26, /* 98 b  */ 27, /* 99 c  */ 28,
    /*100 d  */ 29, /*101 e  */ 30, /*102 f  */ 31, /*103 g  */ 32,
    /*104 h  */ 33, /*105 i  */ 34, /*106 j  */ 35, /*107 k  */ 36,
    /*108 l  */ 37, /*109 m  */ 38, /*110 n  */ 39, /*111 o  */ 40,
    /*112 p  */ 41, /*113 q  */ 42, /*114 r  */ 43, /*115 s  */ 44,
    /*116 t  */ 45, /*117 u  */ 46, /*118 v  */ 47, /*119 w  */ 48,
    /*120 x  */ 49, /*121 y  */ 50, /*122 z  */ 51, /*123 {  */ __,
    /*124 |  */ __, /*125 }  */ __, /*126 ~  */ __, /*127 DEL*/ __,
    #undef __
};

#ifndef NDEBUG
void base64_test_tables()
{
    for(size_t i = 0; i < C4_COUNTOF(detail::base64_sextet_to_char_); ++i)
    {
        char s2c = base64_sextet_to_char_[i];
        char c2s = base64_char_to_sextet_[(int)s2c];
        C4_CHECK((size_t)c2s == i);
    }
    for(size_t i = 0; i < C4_COUNTOF(detail::base64_char_to_sextet_); ++i)
    {
        char c2s = base64_char_to_sextet_[i];
        if(c2s == char(-1))
            continue;
        char s2c = base64_sextet_to_char_[(int)c2s];
        C4_CHECK((size_t)s2c == i);
    }
}
#endif
} // namespace detail


bool base64_valid(csubstr encoded)
{
    if(encoded.len % 4) return false;
    for(const char c : encoded)
    {
        if(c < 0/* || c >= 128*/)
            return false;
        if(c == '=')
            continue;
        if(detail::base64_char_to_sextet_[c] == char(-1))
            return false;
    }
    return true;
}


size_t base64_encode(substr buf, cblob data)
{
    #define c4append_(c) { if(pos < buf.len) { buf.str[pos] = (c); } ++pos; }
    #define c4append_idx_(char_idx) \
    {\
         C4_XASSERT((char_idx) < sizeof(detail::base64_sextet_to_char_));\
         c4append_(detail::base64_sextet_to_char_[(char_idx)]);\
    }

    size_t rem, pos = 0;
    constexpr const uint32_t sextet_mask = uint32_t(1 << 6) - 1;
    const unsigned char *C4_RESTRICT d = (unsigned char *) data.buf; // cast to unsigned to avoid wrapping high-bits
    for(rem = data.len; rem >= 3; rem -= 3, d += 3)
    {
        const uint32_t val = ((uint32_t(d[0]) << 16) | (uint32_t(d[1]) << 8) | (uint32_t(d[2])));
        c4append_idx_((val >> 18) & sextet_mask);
        c4append_idx_((val >> 12) & sextet_mask);
        c4append_idx_((val >>  6) & sextet_mask);
        c4append_idx_((val      ) & sextet_mask);
    }
    C4_ASSERT(rem < 3);
    if(rem == 2)
    {
        const uint32_t val = ((uint32_t(d[0]) << 16) | (uint32_t(d[1]) << 8));
        c4append_idx_((val >> 18) & sextet_mask);
        c4append_idx_((val >> 12) & sextet_mask);
        c4append_idx_((val >>  6) & sextet_mask);
        c4append_('=');
    }
    else if(rem == 1)
    {
        const uint32_t val = ((uint32_t(d[0]) << 16));
        c4append_idx_((val >> 18) & sextet_mask);
        c4append_idx_((val >> 12) & sextet_mask);
        c4append_('=');
        c4append_('=');
    }
    return pos;

    #undef c4append_
    #undef c4append_idx_
}


size_t base64_decode(csubstr encoded, blob data)
{
    #define c4append_(c) { if(wpos < data.len) { data.buf[wpos] = static_cast<c4::byte>(c); } ++wpos; }
    #define c4appendval_(c, shift)\
    {\
        C4_XASSERT(c >= 0);\
        C4_XASSERT(size_t(c) < sizeof(detail::base64_char_to_sextet_));\
        val |= static_cast<uint32_t>(detail::base64_char_to_sextet_[(c)]) << ((shift) * 6);\
    }

    C4_ASSERT(base64_valid(encoded));
    C4_CHECK(encoded.len % 4 == 0);
    size_t wpos = 0;  // the write position
    const char *C4_RESTRICT d = encoded.str;
    constexpr const uint32_t full_byte = 0xff;
    // process every quartet of input 6 bits --> triplet of output bytes
    for(size_t rpos = 0; rpos < encoded.len; rpos += 4, d += 4)
    {
        if(d[2] == '=' || d[3] == '=') // skip the last quartet if it is padded
        {
            C4_ASSERT(d + 4 == encoded.str + encoded.len);
            break;
        }
        uint32_t val = 0;
        c4appendval_(d[3], 0);
        c4appendval_(d[2], 1);
        c4appendval_(d[1], 2);
        c4appendval_(d[0], 3);
        c4append_((val >> (2 * 8)) & full_byte);
        c4append_((val >> (1 * 8)) & full_byte);
        c4append_((val           ) & full_byte);
    }
    // deal with the last quartet when it is padded
    if(d == encoded.str + encoded.len)
        return wpos;
    if(d[2] == '=') // 2 padding chars
    {
        C4_ASSERT(d + 4 == encoded.str + encoded.len);
        C4_ASSERT(d[3] == '=');
        uint32_t val = 0;
        c4appendval_(d[1], 2);
        c4appendval_(d[0], 3);
        c4append_((val >> (2 * 8)) & full_byte);
    }
    else if(d[3] == '=') // 1 padding char
    {
        C4_ASSERT(d + 4 == encoded.str + encoded.len);
        uint32_t val = 0;
        c4appendval_(d[2], 1);
        c4appendval_(d[1], 2);
        c4appendval_(d[0], 3);
        c4append_((val >> (2 * 8)) & full_byte);
        c4append_((val >> (1 * 8)) & full_byte);
    }
    return wpos;
    #undef c4append_
    #undef c4appendval_
}

} // namespace c4

#ifdef __clang__
#    pragma clang diagnostic pop
#elif defined(__GNUC__)
#    pragma GCC diagnostic pop
#endif

#endif /* C4CORE_SINGLE_HDR_DEFINE_NOW */


// (end https://github.com/biojppm/c4core/src/c4/base64.cpp)

#define C4_WINDOWS_POP_HPP_



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/windows_push.hpp
// https://github.com/biojppm/c4core/src/c4/windows_push.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_WINDOWS_PUSH_HPP_
#define _C4_WINDOWS_PUSH_HPP_

/** @file windows_push.hpp sets up macros to include windows header files
 * without pulling in all of <windows.h>
 *
 * @see #include windows_pop.hpp to undefine these macros
 *
 * @see https://aras-p.info/blog/2018/01/12/Minimizing-windows.h/ */


#if defined(_WIN64) || defined(_WIN32)

#if defined(_M_AMD64)
#   ifndef _AMD64_
#       define _c4_AMD64_
#       define _AMD64_
#   endif
#elif defined(_M_IX86)
#   ifndef _X86_
#       define _c4_X86_
#       define _X86_
#   endif
#elif defined(_M_ARM64)
#   ifndef _ARM64_
#       define _c4_ARM64_
#       define _ARM64_
#   endif
#elif defined(_M_ARM)
#   ifndef _ARM_
#       define _c4_ARM_
#       define _ARM_
#   endif
#endif

#ifndef NOMINMAX
#    define _c4_NOMINMAX
#    define NOMINMAX
#endif

#ifndef NOGDI
#    define _c4_NOGDI
#    define NOGDI
#endif

#ifndef VC_EXTRALEAN
#    define _c4_VC_EXTRALEAN
#    define VC_EXTRALEAN
#endif

#ifndef WIN32_LEAN_AND_MEAN
#    define _c4_WIN32_LEAN_AND_MEAN
#    define WIN32_LEAN_AND_MEAN
#endif

/*  If defined, the following flags inhibit definition
 *     of the indicated items.
 *
 *  NOGDICAPMASKS     - CC_*, LC_*, PC_*, CP_*, TC_*, RC_
 *  NOVIRTUALKEYCODES - VK_*
 *  NOWINMESSAGES     - WM_*, EM_*, LB_*, CB_*
 *  NOWINSTYLES       - WS_*, CS_*, ES_*, LBS_*, SBS_*, CBS_*
 *  NOSYSMETRICS      - SM_*
 *  NOMENUS           - MF_*
 *  NOICONS           - IDI_*
 *  NOKEYSTATES       - MK_*
 *  NOSYSCOMMANDS     - SC_*
 *  NORASTEROPS       - Binary and Tertiary raster ops
 *  NOSHOWWINDOW      - SW_*
 *  OEMRESOURCE       - OEM Resource values
 *  NOATOM            - Atom Manager routines
 *  NOCLIPBOARD       - Clipboard routines
 *  NOCOLOR           - Screen colors
 *  NOCTLMGR          - Control and Dialog routines
 *  NODRAWTEXT        - DrawText() and DT_*
 *  NOGDI             - All GDI defines and routines
 *  NOKERNEL          - All KERNEL defines and routines
 *  NOUSER            - All USER defines and routines
 *  NONLS             - All NLS defines and routines
 *  NOMB              - MB_* and MessageBox()
 *  NOMEMMGR          - GMEM_*, LMEM_*, GHND, LHND, associated routines
 *  NOMETAFILE        - typedef METAFILEPICT
 *  NOMINMAX          - Macros min(a,b) and max(a,b)
 *  NOMSG             - typedef MSG and associated routines
 *  NOOPENFILE        - OpenFile(), OemToAnsi, AnsiToOem, and OF_*
 *  NOSCROLL          - SB_* and scrolling routines
 *  NOSERVICE         - All Service Controller routines, SERVICE_ equates, etc.
 *  NOSOUND           - Sound driver routines
 *  NOTEXTMETRIC      - typedef TEXTMETRIC and associated routines
 *  NOWH              - SetWindowsHook and WH_*
 *  NOWINOFFSETS      - GWL_*, GCL_*, associated routines
 *  NOCOMM            - COMM driver routines
 *  NOKANJI           - Kanji support stuff.
 *  NOHELP            - Help engine interface.
 *  NOPROFILER        - Profiler interface.
 *  NODEFERWINDOWPOS  - DeferWindowPos routines
 *  NOMCX             - Modem Configuration Extensions
 */

#endif /* defined(_WIN64) || defined(_WIN32) */

#endif /* _C4_WINDOWS_PUSH_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/windows_push.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/windows.hpp
// https://github.com/biojppm/c4core/src/c4/windows.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_WINDOWS_HPP_
#define _C4_WINDOWS_HPP_

#if defined(_WIN64) || defined(_WIN32)
// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/windows_push.hpp
//#include "c4/windows_push.hpp"
#if !defined(C4_WINDOWS_PUSH_HPP_) && !defined(_C4_WINDOWS_PUSH_HPP_)
#error "amalgamate: file c4/windows_push.hpp must have been included at this point"
#endif /* C4_WINDOWS_PUSH_HPP_ */

#include <windows.h>
// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/windows_pop.hpp
//#include "c4/windows_pop.hpp"
#if !defined(C4_WINDOWS_POP_HPP_) && !defined(_C4_WINDOWS_POP_HPP_)
#error "amalgamate: file c4/windows_pop.hpp must have been included at this point"
#endif /* C4_WINDOWS_POP_HPP_ */

#endif

#endif /* _C4_WINDOWS_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/windows.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/windows_pop.hpp
// https://github.com/biojppm/c4core/src/c4/windows_pop.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_WINDOWS_POP_HPP_
#define _C4_WINDOWS_POP_HPP_

#if defined(_WIN64) || defined(_WIN32)

#ifdef _c4_AMD64_
#    undef _c4_AMD64_
#    undef _AMD64_
#endif
#ifdef _c4_X86_
#    undef _c4_X86_
#    undef _X86_
#endif
#ifdef _c4_ARM_
#    undef _c4_ARM_
#    undef _ARM_
#endif

#ifdef _c4_NOMINMAX
#    undef _c4_NOMINMAX
#    undef NOMINMAX
#endif

#ifdef NOGDI
#    undef _c4_NOGDI
#    undef NOGDI
#endif

#ifdef VC_EXTRALEAN
#    undef _c4_VC_EXTRALEAN
#    undef VC_EXTRALEAN
#endif

#ifdef WIN32_LEAN_AND_MEAN
#    undef _c4_WIN32_LEAN_AND_MEAN
#    undef WIN32_LEAN_AND_MEAN
#endif

#endif /* defined(_WIN64) || defined(_WIN32) */

#endif /* _C4_WINDOWS_POP_HPP_ */


// (end https://github.com/biojppm/c4core/src/c4/windows_pop.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/error.cpp
// https://github.com/biojppm/c4core/src/c4/error.cpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifdef C4CORE_SINGLE_HDR_DEFINE_NOW
// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/error.hpp
//#include "c4/error.hpp"
#if !defined(C4_ERROR_HPP_) && !defined(_C4_ERROR_HPP_)
#error "amalgamate: file c4/error.hpp must have been included at this point"
#endif /* C4_ERROR_HPP_ */


//included above:
//#include <stdlib.h>
//included above:
//#include <stdio.h>
//included above:
//#include <stdarg.h>

#define C4_LOGF_ERR(...) fprintf(stderr, __VA_ARGS__); fflush(stderr)
#define C4_LOGF_WARN(...) fprintf(stderr, __VA_ARGS__); fflush(stderr)
#define C4_LOGP(msg, ...) printf(msg)

#if defined(C4_XBOX) || (defined(C4_WIN) && defined(C4_MSVC))
// amalgamate: removed include of
// https://github.com/biojppm/c4core/src/c4/windows.hpp
//#   include "c4/windows.hpp"
#if !defined(C4_WINDOWS_HPP_) && !defined(_C4_WINDOWS_HPP_)
#error "amalgamate: file c4/windows.hpp must have been included at this point"
#endif /* C4_WINDOWS_HPP_ */

#elif defined(C4_PS4)
#   include <libdbg.h>
#elif defined(C4_UNIX) || defined(C4_LINUX)
#   include <sys/stat.h>
//included above:
//#   include <cstring>
#   include <fcntl.h>
#elif defined(C4_MACOS) || defined(C4_IOS)
//included above:
//#   include <assert.h>
#   include <stdbool.h>
#   include <sys/types.h>
#   include <sys/sysctl.h>
#endif
// the amalgamation tool is dumb and was omitting this include under MACOS.
// So do it only once:
#if defined(C4_UNIX) || defined(C4_LINUX) || defined(C4_MACOS) || defined(C4_IOS)
#   include <unistd.h>
#endif

#if defined(C4_EXCEPTIONS_ENABLED) && defined(C4_ERROR_THROWS_EXCEPTION)
#   include <exception>
#endif

#ifdef __clang__
#   pragma clang diagnostic push
#   pragma clang diagnostic ignored "-Wformat-nonliteral"
#elif defined(__GNUC__)
#   pragma GCC diagnostic push
#   pragma GCC diagnostic ignored "-Wformat-nonliteral"
#endif


//-----------------------------------------------------------------------------
namespace c4 {

static error_flags         s_error_flags = ON_ERROR_DEFAULTS;
static error_callback_type s_error_callback = nullptr;

//-----------------------------------------------------------------------------

error_flags get_error_flags()
{
    return s_error_flags;
}
void set_error_flags(error_flags flags)
{
    s_error_flags = flags;
}

error_callback_type get_error_callback()
{
    return s_error_callback;
}
/** Set the function which is called when an error occurs. */
void set_error_callback(error_callback_type cb)
{
    s_error_callback = cb;
}

//-----------------------------------------------------------------------------

void handle_error(srcloc where, const char *fmt, ...)
{
    char buf[1024];
    size_t msglen = 0;
    if(s_error_flags & (ON_ERROR_LOG|ON_ERROR_CALLBACK))
    {
        va_list args;
        va_start(args, fmt);
        int ilen = vsnprintf(buf, sizeof(buf), fmt, args); // ss.vprintf(fmt, args);
        va_end(args);
        msglen = ilen >= 0 && ilen < (int)sizeof(buf) ? static_cast<size_t>(ilen) : sizeof(buf)-1;
    }

    if(s_error_flags & ON_ERROR_LOG)
    {
        C4_LOGF_ERR("\n");
#if defined(C4_ERROR_SHOWS_FILELINE) && defined(C4_ERROR_SHOWS_FUNC)
        C4_LOGF_ERR("%s:%d: ERROR: %s\n", where.file, where.line, buf);
        C4_LOGF_ERR("%s:%d: ERROR here: %s\n", where.file, where.line, where.func);
#elif defined(C4_ERROR_SHOWS_FILELINE)
        C4_LOGF_ERR("%s:%d: ERROR: %s\n", where.file, where.line, buf);
#elif ! defined(C4_ERROR_SHOWS_FUNC)
        C4_LOGF_ERR("ERROR: %s\n", buf);
#endif
    }

    if(s_error_flags & ON_ERROR_CALLBACK)
    {
        if(s_error_callback)
        {
            s_error_callback(buf, msglen/*ss.c_strp(), ss.tellp()*/);
        }
    }

    if(s_error_flags & ON_ERROR_ABORT)
    {
        abort();
    }

    if(s_error_flags & ON_ERROR_THROW)
    {
#if defined(C4_EXCEPTIONS_ENABLED) && defined(C4_ERROR_THROWS_EXCEPTION)
        throw Exception(buf);
#else
        abort();
#endif
    }
}

//-----------------------------------------------------------------------------

void handle_warning(srcloc where, const char *fmt, ...)
{
    va_list args;
    char buf[1024]; //sstream<c4::string> ss;
    va_start(args, fmt);
    vsnprintf(buf, sizeof(buf), fmt, args);
    va_end(args);
    C4_LOGF_WARN("\n");
#if defined(C4_ERROR_SHOWS_FILELINE) && defined(C4_ERROR_SHOWS_FUNC)
    C4_LOGF_WARN("%s:%d: WARNING: %s\n", where.file, where.line, buf/*ss.c_strp()*/);
    C4_LOGF_WARN("%s:%d: WARNING: here: %s\n", where.file, where.line, where.func);
#elif defined(C4_ERROR_SHOWS_FILELINE)
    C4_LOGF_WARN("%s:%d: WARNING: %s\n", where.file, where.line, buf/*ss.c_strp()*/);
#elif ! defined(C4_ERROR_SHOWS_FUNC)
    C4_LOGF_WARN("WARNING: %s\n", buf/*ss.c_strp()*/);
#endif
    //c4::log.flush();
}

//-----------------------------------------------------------------------------
bool is_debugger_attached()
{
#if defined(C4_UNIX) || defined(C4_LINUX)
    static bool first_call = true;
    static bool first_call_result = false;
    if(first_call)
    {
        first_call = false;
        //! @see http://stackoverflow.com/questions/3596781/how-to-detect-if-the-current-process-is-being-run-by-gdb
        //! (this answer: http://stackoverflow.com/a/24969863/3968589 )
        char buf[1024] = "";

        int status_fd = open("/proc/self/status", O_RDONLY);
        if (status_fd == -1)
        {
            return 0;
        }

        ssize_t num_read = ::read(status_fd, buf, sizeof(buf));

        if (num_read > 0)
        {
            static const char TracerPid[] = "TracerPid:";
            char *tracer_pid;

            if(num_read < 1024)
            {
                buf[num_read] = 0;
            }
            tracer_pid = strstr(buf, TracerPid);
            if (tracer_pid)
            {
                first_call_result = !!::atoi(tracer_pid + sizeof(TracerPid) - 1);
            }
        }
    }
    return first_call_result;
#elif defined(C4_PS4)
    return (sceDbgIsDebuggerAttached() != 0);
#elif defined(C4_XBOX) || (defined(C4_WIN) && defined(C4_MSVC))
    return IsDebuggerPresent() != 0;
#elif defined(C4_MACOS) || defined(C4_IOS)
    // https://stackoverflow.com/questions/2200277/detecting-debugger-on-mac-os-x
    // Returns true if the current process is being debugged (either
    // running under the debugger or has a debugger attached post facto).
    int                 junk;
    int                 mib[4];
    struct kinfo_proc   info;
    size_t              size;

    // Initialize the flags so that, if sysctl fails for some bizarre
    // reason, we get a predictable result.

    info.kp_proc.p_flag = 0;

    // Initialize mib, which tells sysctl the info we want, in this case
    // we're looking for information about a specific process ID.

    mib[0] = CTL_KERN;
    mib[1] = KERN_PROC;
    mib[2] = KERN_PROC_PID;
    mib[3] = getpid();

    // Call sysctl.

    size = sizeof(info);
    junk = sysctl(mib, sizeof(mib) / sizeof(*mib), &info, &size, NULL, 0);
    assert(junk == 0);

    // We're being debugged if the P_TRACED flag is set.
    return ((info.kp_proc.p_flag & P_TRACED) != 0);
#else
    return false;
#endif
} // is_debugger_attached()

} // namespace c4


#ifdef __clang__
#   pragma clang diagnostic pop
#elif defined(__GNUC__)
#   pragma GCC diagnostic pop
#endif

#endif /* C4CORE_SINGLE_HDR_DEFINE_NOW */


// (end https://github.com/biojppm/c4core/src/c4/error.cpp)

#endif /* _C4CORE_SINGLE_HEADER_AMALGAMATED_HPP_ */



// (end https://github.com/biojppm/rapidyaml/src/c4/c4core_all.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/export.hpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/export.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef C4_YML_EXPORT_HPP_
#define C4_YML_EXPORT_HPP_

#ifdef _WIN32
    #ifdef RYML_SHARED
        #ifdef RYML_EXPORTS
            #define RYML_EXPORT __declspec(dllexport)
        #else
            #define RYML_EXPORT __declspec(dllimport)
        #endif
    #else
        #define RYML_EXPORT
    #endif
#else
    #define RYML_EXPORT
#endif

#endif /* C4_YML_EXPORT_HPP_ */


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/export.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/common.hpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/common.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_YML_COMMON_HPP_
#define _C4_YML_COMMON_HPP_

//included above:
//#include <cstddef>
// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/substr.hpp
//#include <c4/substr.hpp>
#if !defined(C4_SUBSTR_HPP_) && !defined(_C4_SUBSTR_HPP_)
#error "amalgamate: file c4/substr.hpp must have been included at this point"
#endif /* C4_SUBSTR_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/export.hpp
//#include <c4/yml/export.hpp>
#if !defined(C4_YML_EXPORT_HPP_) && !defined(_C4_YML_EXPORT_HPP_)
#error "amalgamate: file c4/yml/export.hpp must have been included at this point"
#endif /* C4_YML_EXPORT_HPP_ */



#ifndef RYML_USE_ASSERT
#   define RYML_USE_ASSERT C4_USE_ASSERT
#endif


#if RYML_USE_ASSERT
#   define RYML_ASSERT(cond) RYML_CHECK(cond)
#   define RYML_ASSERT_MSG(cond, msg) RYML_CHECK_MSG(cond, msg)
#else
#   define RYML_ASSERT(cond)
#   define RYML_ASSERT_MSG(cond, msg)
#endif


#if defined(NDEBUG) || defined(C4_NO_DEBUG_BREAK)
#   define RYML_DEBUG_BREAK()
#else
#   define RYML_DEBUG_BREAK()                               \
    {                                                       \
        if(c4::get_error_flags() & c4::ON_ERROR_DEBUGBREAK) \
        {                                                   \
            C4_DEBUG_BREAK();                               \
        }                                                   \
    }
#endif


#define RYML_CHECK(cond)                                                \
    do {                                                                \
        if(!(cond))                                                     \
        {                                                               \
            RYML_DEBUG_BREAK()                                          \
            c4::yml::error("check failed: " #cond, c4::yml::Location(__FILE__, __LINE__, 0)); \
        }                                                               \
    } while(0)

#define RYML_CHECK_MSG(cond, msg)                                       \
    do                                                                  \
    {                                                                   \
        if(!(cond))                                                     \
        {                                                               \
            RYML_DEBUG_BREAK()                                          \
            c4::yml::error(msg ": check failed: " #cond, c4::yml::Location(__FILE__, __LINE__, 0)); \
        }                                                               \
    } while(0)


#if C4_CPP >= 14
#   define RYML_DEPRECATED(msg) [[deprecated(msg)]]
#else
#   if defined(_MSC_VER)
#       define RYML_DEPRECATED(msg) __declspec(deprecated(msg))
#   else // defined(__GNUC__) || defined(__clang__)
#       define RYML_DEPRECATED(msg) __attribute__((deprecated(msg)))
#   endif
#endif


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

namespace c4 {
namespace yml {

enum : size_t {
    /** a null position */
    npos = size_t(-1),
    /** an index to none */
    NONE = size_t(-1)
};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

//! holds a position into a source buffer
struct RYML_EXPORT LineCol
{
    //! number of bytes from the beginning of the source buffer
    size_t offset;
    //! line
    size_t line;
    //! column
    size_t col;

    LineCol() : offset(), line(), col() {}
    //! construct from line and column
    LineCol(size_t l, size_t c) : offset(0), line(l), col(c) {}
    //! construct from offset, line and column
    LineCol(size_t o, size_t l, size_t c) : offset(o), line(l), col(c) {}
};


//! a source file position
struct RYML_EXPORT Location : public LineCol
{
    csubstr name;

    operator bool () const { return !name.empty() || line != 0 || offset != 0; }

    Location() : LineCol(), name() {}
    Location(                         size_t l, size_t c) : LineCol{   l, c}, name( ) {}
    Location(    csubstr n,           size_t l, size_t c) : LineCol{   l, c}, name(n) {}
    Location(    csubstr n, size_t b, size_t l, size_t c) : LineCol{b, l, c}, name(n) {}
    Location(const char *n,           size_t l, size_t c) : LineCol{   l, c}, name(to_csubstr(n)) {}
    Location(const char *n, size_t b, size_t l, size_t c) : LineCol{b, l, c}, name(to_csubstr(n)) {}
};


//-----------------------------------------------------------------------------

/** the type of the function used to report errors. This function must
 * interrupt execution, either by raising an exception or calling
 * std::abort().
 *
 * @warning the error callback must never return: it must either abort
 * or throw an exception. Otherwise, the parser will enter into an
 * infinite loop, or the program may crash. */
using pfn_error = void (*)(const char* msg, size_t msg_len, Location location, void *user_data);
/** the type of the function used to allocate memory */
using pfn_allocate = void* (*)(size_t len, void* hint, void *user_data);
/** the type of the function used to free memory */
using pfn_free = void (*)(void* mem, size_t size, void *user_data);

/** trigger an error: call the current error callback. */
RYML_EXPORT void error(const char *msg, size_t msg_len, Location loc);
/** @overload error */
inline void error(const char *msg, size_t msg_len)
{
    error(msg, msg_len, Location{});
}
/** @overload error */
template<size_t N>
inline void error(const char (&msg)[N], Location loc)
{
    error(msg, N-1, loc);
}
/** @overload error */
template<size_t N>
inline void error(const char (&msg)[N])
{
    error(msg, N-1, Location{});
}

//-----------------------------------------------------------------------------

/** a c-style callbacks class
 *
 * @warning the error callback must never return: it must either abort
 * or throw an exception. Otherwise, the parser will enter into an
 * infinite loop, or the program may crash. */
struct RYML_EXPORT Callbacks
{
    void *       m_user_data;
    pfn_allocate m_allocate;
    pfn_free     m_free;
    pfn_error    m_error;

    Callbacks();
    Callbacks(void *user_data, pfn_allocate alloc, pfn_free free, pfn_error error_);

    bool operator!= (Callbacks const& that) const { return !operator==(that); }
    bool operator== (Callbacks const& that) const
    {
        return (m_user_data == that.m_user_data &&
                m_allocate == that.m_allocate &&
                m_free == that.m_free &&
                m_error == that.m_error);
    }
};

/** set the global callbacks.
 *
 * @warning the error callback must never return: it must either abort
 * or throw an exception. Otherwise, the parser will enter into an
 * infinite loop, or the program may crash. */
RYML_EXPORT void set_callbacks(Callbacks const& c);
/// get the global callbacks
RYML_EXPORT Callbacks const& get_callbacks();
/// set the global callbacks back to their defaults
RYML_EXPORT void reset_callbacks();

/// @cond dev
#define _RYML_CB_ERR(cb, msg_literal)                                   \
do                                                                      \
{                                                                       \
    const char msg[] = msg_literal;                                     \
    RYML_DEBUG_BREAK()                                                  \
    (cb).m_error(msg, sizeof(msg), c4::yml::Location(__FILE__, 0, __LINE__, 0), (cb).m_user_data); \
} while(0)
#define _RYML_CB_CHECK(cb, cond)                                        \
    do                                                                  \
    {                                                                   \
        if(!(cond))                                                     \
        {                                                               \
            const char msg[] = "check failed: " #cond;                  \
            RYML_DEBUG_BREAK()                                          \
            (cb).m_error(msg, sizeof(msg), c4::yml::Location(__FILE__, 0, __LINE__, 0), (cb).m_user_data); \
        }                                                               \
    } while(0)
#ifdef RYML_USE_ASSERT
#define _RYML_CB_ASSERT(cb, cond) _RYML_CB_CHECK((cb), (cond))
#else
#define _RYML_CB_ASSERT(cb, cond) do {} while(0)
#endif
#define _RYML_CB_ALLOC_HINT(cb, T, num, hint) (T*) (cb).m_allocate((num) * sizeof(T), (hint), (cb).m_user_data)
#define _RYML_CB_ALLOC(cb, T, num) _RYML_CB_ALLOC_HINT((cb), (T), (num), nullptr)
#define _RYML_CB_FREE(cb, buf, T, num)                              \
    do {                                                            \
        (cb).m_free((buf), (num) * sizeof(T), (cb).m_user_data);    \
        (buf) = nullptr;                                            \
    } while(0)



namespace detail {
template<int8_t signedval, uint8_t unsignedval>
struct _charconstant_t
    : public std::conditional<std::is_signed<char>::value,
                              std::integral_constant<int8_t, signedval>,
                              std::integral_constant<uint8_t, unsignedval>>::type
{};
#define _RYML_CHCONST(signedval, unsignedval) ::c4::yml::detail::_charconstant_t<INT8_C(signedval), UINT8_C(unsignedval)>::value
} // namespace detail


namespace detail {
struct _SubstrWriter
{
    substr buf;
    size_t pos;
    _SubstrWriter(substr buf_, size_t pos_=0) : buf(buf_), pos(pos_) {}
    void append(csubstr s)
    {
        C4_ASSERT(!s.overlaps(buf));
        if(pos + s.len <= buf.len)
            memcpy(buf.str + pos, s.str, s.len);
        pos += s.len;
    }
    void append(char c)
    {
        if(pos < buf.len)
            buf.str[pos] = c;
        ++pos;
    }
    void append_n(char c, size_t numtimes)
    {
        if(pos + numtimes < buf.len)
            memset(buf.str + pos, c, numtimes);
        pos += numtimes;
    }
    size_t slack() const { return pos <= buf.len ? buf.len - pos : 0; }
    size_t excess() const { return pos > buf.len ? pos - buf.len : 0; }
    //! get the part written so far
    csubstr curr() const { return pos <= buf.len ? buf.first(pos) : buf; }
    //! get the part that is still free to write to (the remainder)
    substr rem() { return pos < buf.len ? buf.sub(pos) : buf.last(0); }

    size_t advance(size_t more) { pos += more; return pos; }
};
} // namespace detail

/// @endcond

} // namespace yml
} // namespace c4

#endif /* _C4_YML_COMMON_HPP_ */


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/common.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/tree.hpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/tree.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_YML_TREE_HPP_
#define _C4_YML_TREE_HPP_


// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/error.hpp
//#include "c4/error.hpp"
#if !defined(C4_ERROR_HPP_) && !defined(_C4_ERROR_HPP_)
#error "amalgamate: file c4/error.hpp must have been included at this point"
#endif /* C4_ERROR_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/types.hpp
//#include "c4/types.hpp"
#if !defined(C4_TYPES_HPP_) && !defined(_C4_TYPES_HPP_)
#error "amalgamate: file c4/types.hpp must have been included at this point"
#endif /* C4_TYPES_HPP_ */

#ifndef _C4_YML_COMMON_HPP_
// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/common.hpp
//#include "c4/yml/common.hpp"
#if !defined(C4_YML_COMMON_HPP_) && !defined(_C4_YML_COMMON_HPP_)
#error "amalgamate: file c4/yml/common.hpp must have been included at this point"
#endif /* C4_YML_COMMON_HPP_ */

#endif

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/charconv.hpp
//#include <c4/charconv.hpp>
#if !defined(C4_CHARCONV_HPP_) && !defined(_C4_CHARCONV_HPP_)
#error "amalgamate: file c4/charconv.hpp must have been included at this point"
#endif /* C4_CHARCONV_HPP_ */

//included above:
//#include <cmath>
//included above:
//#include <limits>


C4_SUPPRESS_WARNING_MSVC_PUSH
C4_SUPPRESS_WARNING_MSVC(4251) // needs to have dll-interface to be used by clients of struct
C4_SUPPRESS_WARNING_MSVC(4296) // expression is always 'boolean_value'
C4_SUPPRESS_WARNING_GCC_CLANG_PUSH
C4_SUPPRESS_WARNING_GCC("-Wtype-limits")


namespace c4 {
namespace yml {

struct NodeScalar;
struct NodeInit;
struct NodeData;
class NodeRef;
class ConstNodeRef;
class Tree;


/** encode a floating point value to a string. */
template<class T>
size_t to_chars_float(substr buf, T val)
{
    C4_SUPPRESS_WARNING_GCC_CLANG_WITH_PUSH("-Wfloat-equal");
    static_assert(std::is_floating_point<T>::value, "must be floating point");
    if(C4_UNLIKELY(std::isnan(val)))
        return to_chars(buf, csubstr(".nan"));
    else if(C4_UNLIKELY(val == std::numeric_limits<T>::infinity()))
        return to_chars(buf, csubstr(".inf"));
    else if(C4_UNLIKELY(val == -std::numeric_limits<T>::infinity()))
        return to_chars(buf, csubstr("-.inf"));
    return to_chars(buf, val);
    C4_SUPPRESS_WARNING_GCC_CLANG_POP
}


/** decode a floating point from string. Accepts special values: .nan,
 * .inf, -.inf */
template<class T>
bool from_chars_float(csubstr buf, T *C4_RESTRICT val)
{
    static_assert(std::is_floating_point<T>::value, "must be floating point");
    if(C4_LIKELY(from_chars(buf, val)))
    {
        return true;
    }
    else if(C4_UNLIKELY(buf == ".nan" || buf == ".NaN" || buf == ".NAN"))
    {
        *val = std::numeric_limits<T>::quiet_NaN();
        return true;
    }
    else if(C4_UNLIKELY(buf == ".inf" || buf == ".Inf" || buf == ".INF"))
    {
        *val = std::numeric_limits<T>::infinity();
        return true;
    }
    else if(C4_UNLIKELY(buf == "-.inf" || buf == "-.Inf" || buf == "-.INF"))
    {
        *val = -std::numeric_limits<T>::infinity();
        return true;
    }
    else
    {
        return false;
    }
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** the integral type necessary to cover all the bits marking node tags */
using tag_bits = uint16_t;

/** a bit mask for marking tags for types */
typedef enum : tag_bits {
    // container types
    TAG_NONE      =  0,
    TAG_MAP       =  1, /**< !!map   Unordered set of key: value pairs without duplicates. @see https://yaml.org/type/map.html */
    TAG_OMAP      =  2, /**< !!omap  Ordered sequence of key: value pairs without duplicates. @see https://yaml.org/type/omap.html */
    TAG_PAIRS     =  3, /**< !!pairs Ordered sequence of key: value pairs allowing duplicates. @see https://yaml.org/type/pairs.html */
    TAG_SET       =  4, /**< !!set   Unordered set of non-equal values. @see https://yaml.org/type/set.html */
    TAG_SEQ       =  5, /**< !!seq   Sequence of arbitrary values. @see https://yaml.org/type/seq.html */
    // scalar types
    TAG_BINARY    =  6, /**< !!binary A sequence of zero or more octets (8 bit values). @see https://yaml.org/type/binary.html */
    TAG_BOOL      =  7, /**< !!bool   Mathematical Booleans. @see https://yaml.org/type/bool.html */
    TAG_FLOAT     =  8, /**< !!float  Floating-point approximation to real numbers. https://yaml.org/type/float.html */
    TAG_INT       =  9, /**< !!float  Mathematical integers. https://yaml.org/type/int.html */
    TAG_MERGE     = 10, /**< !!merge  Specify one or more mapping to be merged with the current one. https://yaml.org/type/merge.html */
    TAG_NULL      = 11, /**< !!null   Devoid of value. https://yaml.org/type/null.html */
    TAG_STR       = 12, /**< !!str    A sequence of zero or more Unicode characters. https://yaml.org/type/str.html */
    TAG_TIMESTAMP = 13, /**< !!timestamp A point in time https://yaml.org/type/timestamp.html */
    TAG_VALUE     = 14, /**< !!value  Specify the default value of a mapping https://yaml.org/type/value.html */
    TAG_YAML      = 15, /**< !!yaml   Specify the default value of a mapping https://yaml.org/type/yaml.html */
} YamlTag_e;

YamlTag_e to_tag(csubstr tag);
csubstr from_tag(YamlTag_e tag);
csubstr from_tag_long(YamlTag_e tag);
csubstr normalize_tag(csubstr tag);
csubstr normalize_tag_long(csubstr tag);

struct TagDirective
{
    /** Eg `!e!` in `%TAG !e! tag:example.com,2000:app/` */
    csubstr handle;
    /** Eg `tag:example.com,2000:app/` in `%TAG !e! tag:example.com,2000:app/` */
    csubstr prefix;
    /** The next node to which this tag directive applies */
    size_t next_node_id;
};

#ifndef RYML_MAX_TAG_DIRECTIVES
/** the maximum number of tag directives in a Tree */
#define RYML_MAX_TAG_DIRECTIVES 4
#endif



//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------


/** the integral type necessary to cover all the bits marking node types */
using type_bits = uint64_t;


/** a bit mask for marking node types */
typedef enum : type_bits {
    // a convenience define, undefined below
    #define c4bit(v) (type_bits(1) << v)
    NOTYPE  = 0,            ///< no node type is set
    VAL     = c4bit(0),     ///< a leaf node, has a (possibly empty) value
    KEY     = c4bit(1),     ///< is member of a map, must have non-empty key
    MAP     = c4bit(2),     ///< a map: a parent of keyvals
    SEQ     = c4bit(3),     ///< a seq: a parent of vals
    DOC     = c4bit(4),     ///< a document
    STREAM  = c4bit(5)|SEQ, ///< a stream: a seq of docs
    KEYREF  = c4bit(6),     ///< a *reference: the key references an &anchor
    VALREF  = c4bit(7),     ///< a *reference: the val references an &anchor
    KEYANCH = c4bit(8),     ///< the key has an &anchor
    VALANCH = c4bit(9),     ///< the val has an &anchor
    KEYTAG  = c4bit(10),    ///< the key has an explicit tag/type
    VALTAG  = c4bit(11),    ///< the val has an explicit tag/type
    _TYMASK = c4bit(12)-1,  // all the bits up to here
    VALQUO  = c4bit(12),    ///< the val is quoted by '', "", > or |
    KEYQUO  = c4bit(13),    ///< the key is quoted by '', "", > or |
    KEYVAL  = KEY|VAL,
    KEYSEQ  = KEY|SEQ,
    KEYMAP  = KEY|MAP,
    DOCMAP  = DOC|MAP,
    DOCSEQ  = DOC|SEQ,
    DOCVAL  = DOC|VAL,
    _KEYMASK = KEY | KEYQUO | KEYANCH | KEYREF | KEYTAG,
    _VALMASK = VAL | VALQUO | VALANCH | VALREF | VALTAG,
    // these flags are from a work in progress and should not be used yet
    _WIP_STYLE_FLOW_SL = c4bit(14), ///< mark container with single-line flow format (seqs as '[val1,val2], maps as '{key: val, key2: val2}')
    _WIP_STYLE_FLOW_ML = c4bit(15), ///< mark container with multi-line flow format (seqs as '[val1,\nval2], maps as '{key: val,\nkey2: val2}')
    _WIP_STYLE_BLOCK   = c4bit(16), ///< mark container with block format (seqs as '- val\n', maps as 'key: val')
    _WIP_KEY_LITERAL   = c4bit(17), ///< mark key scalar as multiline, block literal |
    _WIP_VAL_LITERAL   = c4bit(18), ///< mark val scalar as multiline, block literal |
    _WIP_KEY_FOLDED    = c4bit(19), ///< mark key scalar as multiline, block folded >
    _WIP_VAL_FOLDED    = c4bit(20), ///< mark val scalar as multiline, block folded >
    _WIP_KEY_SQUO      = c4bit(21), ///< mark key scalar as single quoted
    _WIP_VAL_SQUO      = c4bit(22), ///< mark val scalar as single quoted
    _WIP_KEY_DQUO      = c4bit(23), ///< mark key scalar as double quoted
    _WIP_VAL_DQUO      = c4bit(24), ///< mark val scalar as double quoted
    _WIP_KEY_PLAIN     = c4bit(25), ///< mark key scalar as plain scalar (unquoted, even when multiline)
    _WIP_VAL_PLAIN     = c4bit(26), ///< mark val scalar as plain scalar (unquoted, even when multiline)
    _WIP_KEY_STYLE     = _WIP_KEY_LITERAL|_WIP_KEY_FOLDED|_WIP_KEY_SQUO|_WIP_KEY_DQUO|_WIP_KEY_PLAIN,
    _WIP_VAL_STYLE     = _WIP_VAL_LITERAL|_WIP_VAL_FOLDED|_WIP_VAL_SQUO|_WIP_VAL_DQUO|_WIP_VAL_PLAIN,
    _WIP_KEY_FT_NL     = c4bit(27), ///< features: mark key scalar as having \n in its contents
    _WIP_VAL_FT_NL     = c4bit(28), ///< features: mark val scalar as having \n in its contents
    _WIP_KEY_FT_SQ     = c4bit(29), ///< features: mark key scalar as having single quotes in its contents
    _WIP_VAL_FT_SQ     = c4bit(30), ///< features: mark val scalar as having single quotes in its contents
    _WIP_KEY_FT_DQ     = c4bit(31), ///< features: mark key scalar as having double quotes in its contents
    _WIP_VAL_FT_DQ     = c4bit(32), ///< features: mark val scalar as having double quotes in its contents
    #undef c4bit
} NodeType_e;


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** wraps a NodeType_e element with some syntactic sugar and predicates */
struct NodeType
{
public:

    NodeType_e type;

public:

    C4_ALWAYS_INLINE NodeType() : type(NOTYPE) {}
    C4_ALWAYS_INLINE NodeType(NodeType_e t) : type(t) {}
    C4_ALWAYS_INLINE NodeType(type_bits t) : type((NodeType_e)t) {}

    C4_ALWAYS_INLINE const char *type_str() const { return type_str(type); }
    static const char* type_str(NodeType_e t);

    C4_ALWAYS_INLINE void set(NodeType_e t) { type = t; }
    C4_ALWAYS_INLINE void set(type_bits  t) { type = (NodeType_e)t; }

    C4_ALWAYS_INLINE void add(NodeType_e t) { type = (NodeType_e)(type|t); }
    C4_ALWAYS_INLINE void add(type_bits  t) { type = (NodeType_e)(type|t); }

    C4_ALWAYS_INLINE void rem(NodeType_e t) { type = (NodeType_e)(type & ~t); }
    C4_ALWAYS_INLINE void rem(type_bits  t) { type = (NodeType_e)(type & ~t); }

    C4_ALWAYS_INLINE void clear() { type = NOTYPE; }

public:

    C4_ALWAYS_INLINE operator NodeType_e      & C4_RESTRICT ()       { return type; }
    C4_ALWAYS_INLINE operator NodeType_e const& C4_RESTRICT () const { return type; }

    C4_ALWAYS_INLINE bool operator== (NodeType_e t) const { return type == t; }
    C4_ALWAYS_INLINE bool operator!= (NodeType_e t) const { return type != t; }

public:

    #if defined(__clang__)
    #   pragma clang diagnostic push
    #   pragma clang diagnostic ignored "-Wnull-dereference"
    #elif defined(__GNUC__)
    #   pragma GCC diagnostic push
    #   if __GNUC__ >= 6
    #       pragma GCC diagnostic ignored "-Wnull-dereference"
    #   endif
    #endif

    C4_ALWAYS_INLINE bool is_notype() const { return type == NOTYPE; }
    C4_ALWAYS_INLINE bool is_stream() const { return ((type & STREAM) == STREAM) != 0; }
    C4_ALWAYS_INLINE bool is_doc() const { return (type & DOC) != 0; }
    C4_ALWAYS_INLINE bool is_container() const { return (type & (MAP|SEQ|STREAM)) != 0; }
    C4_ALWAYS_INLINE bool is_map() const { return (type & MAP) != 0; }
    C4_ALWAYS_INLINE bool is_seq() const { return (type & SEQ) != 0; }
    C4_ALWAYS_INLINE bool has_key() const { return (type & KEY) != 0; }
    C4_ALWAYS_INLINE bool has_val() const { return (type & VAL) != 0; }
    C4_ALWAYS_INLINE bool is_val() const { return (type & KEYVAL) == VAL; }
    C4_ALWAYS_INLINE bool is_keyval() const { return (type & KEYVAL) == KEYVAL; }
    C4_ALWAYS_INLINE bool has_key_tag() const { return (type & (KEY|KEYTAG)) == (KEY|KEYTAG); }
    C4_ALWAYS_INLINE bool has_val_tag() const { return ((type & VALTAG) && (type & (VAL|MAP|SEQ))); }
    C4_ALWAYS_INLINE bool has_key_anchor() const { return (type & (KEY|KEYANCH)) == (KEY|KEYANCH); }
    C4_ALWAYS_INLINE bool is_key_anchor() const { return (type & (KEY|KEYANCH)) == (KEY|KEYANCH); }
    C4_ALWAYS_INLINE bool has_val_anchor() const { return (type & VALANCH) != 0 && (type & (VAL|SEQ|MAP)) != 0; }
    C4_ALWAYS_INLINE bool is_val_anchor() const { return (type & VALANCH) != 0 && (type & (VAL|SEQ|MAP)) != 0; }
    C4_ALWAYS_INLINE bool has_anchor() const { return (type & (KEYANCH|VALANCH)) != 0; }
    C4_ALWAYS_INLINE bool is_anchor() const { return (type & (KEYANCH|VALANCH)) != 0; }
    C4_ALWAYS_INLINE bool is_key_ref() const { return (type & KEYREF) != 0; }
    C4_ALWAYS_INLINE bool is_val_ref() const { return (type & VALREF) != 0; }
    C4_ALWAYS_INLINE bool is_ref() const { return (type & (KEYREF|VALREF)) != 0; }
    C4_ALWAYS_INLINE bool is_anchor_or_ref() const { return (type & (KEYANCH|VALANCH|KEYREF|VALREF)) != 0; }
    C4_ALWAYS_INLINE bool is_key_quoted() const { return (type & (KEY|KEYQUO)) == (KEY|KEYQUO); }
    C4_ALWAYS_INLINE bool is_val_quoted() const { return (type & (VAL|VALQUO)) == (VAL|VALQUO); }
    C4_ALWAYS_INLINE bool is_quoted() const { return (type & (KEY|KEYQUO)) == (KEY|KEYQUO) || (type & (VAL|VALQUO)) == (VAL|VALQUO); }

    // these predicates are a work in progress and subject to change. Don't use yet.
    C4_ALWAYS_INLINE bool default_block() const { return (type & (_WIP_STYLE_BLOCK|_WIP_STYLE_FLOW_ML|_WIP_STYLE_FLOW_SL)) == 0; }
    C4_ALWAYS_INLINE bool marked_block() const { return (type & (_WIP_STYLE_BLOCK)) != 0; }
    C4_ALWAYS_INLINE bool marked_flow_sl() const { return (type & (_WIP_STYLE_FLOW_SL)) != 0; }
    C4_ALWAYS_INLINE bool marked_flow_ml() const { return (type & (_WIP_STYLE_FLOW_ML)) != 0; }
    C4_ALWAYS_INLINE bool marked_flow() const { return (type & (_WIP_STYLE_FLOW_ML|_WIP_STYLE_FLOW_SL)) != 0; }
    C4_ALWAYS_INLINE bool key_marked_literal() const { return (type & (_WIP_KEY_LITERAL)) != 0; }
    C4_ALWAYS_INLINE bool val_marked_literal() const { return (type & (_WIP_VAL_LITERAL)) != 0; }
    C4_ALWAYS_INLINE bool key_marked_folded() const { return (type & (_WIP_KEY_FOLDED)) != 0; }
    C4_ALWAYS_INLINE bool val_marked_folded() const { return (type & (_WIP_VAL_FOLDED)) != 0; }
    C4_ALWAYS_INLINE bool key_marked_squo() const { return (type & (_WIP_KEY_SQUO)) != 0; }
    C4_ALWAYS_INLINE bool val_marked_squo() const { return (type & (_WIP_VAL_SQUO)) != 0; }
    C4_ALWAYS_INLINE bool key_marked_dquo() const { return (type & (_WIP_KEY_DQUO)) != 0; }
    C4_ALWAYS_INLINE bool val_marked_dquo() const { return (type & (_WIP_VAL_DQUO)) != 0; }
    C4_ALWAYS_INLINE bool key_marked_plain() const { return (type & (_WIP_KEY_PLAIN)) != 0; }
    C4_ALWAYS_INLINE bool val_marked_plain() const { return (type & (_WIP_VAL_PLAIN)) != 0; }

    #if defined(__clang__)
    #   pragma clang diagnostic pop
    #elif defined(__GNUC__)
    #   pragma GCC diagnostic pop
    #endif

};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** a node scalar is a csubstr, which may be tagged and anchored. */
struct NodeScalar
{
    csubstr tag;
    csubstr scalar;
    csubstr anchor;

public:

    /// initialize as an empty scalar
    inline NodeScalar() noexcept : tag(), scalar(), anchor() {}

    /// initialize as an untagged scalar
    template<size_t N>
    inline NodeScalar(const char (&s)[N]) noexcept : tag(), scalar(s), anchor() {}
    inline NodeScalar(csubstr      s    ) noexcept : tag(), scalar(s), anchor() {}

    /// initialize as a tagged scalar
    template<size_t N, size_t M>
    inline NodeScalar(const char (&t)[N], const char (&s)[N]) noexcept : tag(t), scalar(s), anchor() {}
    inline NodeScalar(csubstr      t    , csubstr      s    ) noexcept : tag(t), scalar(s), anchor() {}

public:

    ~NodeScalar() noexcept = default;
    NodeScalar(NodeScalar &&) noexcept = default;
    NodeScalar(NodeScalar const&) noexcept = default;
    NodeScalar& operator= (NodeScalar &&) noexcept = default;
    NodeScalar& operator= (NodeScalar const&) noexcept = default;

public:

    bool empty() const noexcept { return tag.empty() && scalar.empty() && anchor.empty(); }

    void clear() noexcept { tag.clear(); scalar.clear(); anchor.clear(); }

    void set_ref_maybe_replacing_scalar(csubstr ref, bool has_scalar) noexcept
    {
        csubstr trimmed = ref.begins_with('*') ? ref.sub(1) : ref;
        anchor = trimmed;
        if((!has_scalar) || !scalar.ends_with(trimmed))
            scalar = ref;
    }
};
C4_MUST_BE_TRIVIAL_COPY(NodeScalar);


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** convenience class to initialize nodes */
struct NodeInit
{

    NodeType   type;
    NodeScalar key;
    NodeScalar val;

public:

    /// initialize as an empty node
    NodeInit() : type(NOTYPE), key(), val() {}
    /// initialize as a typed node
    NodeInit(NodeType_e t) : type(t), key(), val() {}
    /// initialize as a sequence member
    NodeInit(NodeScalar const& v) : type(VAL), key(), val(v) { _add_flags(); }
    /// initialize as a mapping member
    NodeInit(              NodeScalar const& k, NodeScalar const& v) : type(KEYVAL), key(k.tag, k.scalar), val(v.tag, v.scalar) { _add_flags(); }
    /// initialize as a mapping member with explicit type
    NodeInit(NodeType_e t, NodeScalar const& k, NodeScalar const& v) : type(t     ), key(k.tag, k.scalar), val(v.tag, v.scalar) { _add_flags(); }
    /// initialize as a mapping member with explicit type (eg SEQ or MAP)
    NodeInit(NodeType_e t, NodeScalar const& k                     ) : type(t     ), key(k.tag, k.scalar), val(               ) { _add_flags(KEY); }

public:

    void clear()
    {
        type.clear();
        key.clear();
        val.clear();
    }

    void _add_flags(type_bits more_flags=0)
    {
        type = (type|more_flags);
        if( ! key.tag.empty())
            type = (type|KEYTAG);
        if( ! val.tag.empty())
            type = (type|VALTAG);
        if( ! key.anchor.empty())
            type = (type|KEYANCH);
        if( ! val.anchor.empty())
            type = (type|VALANCH);
    }

    bool _check() const
    {
        // key cannot be empty
        RYML_ASSERT(key.scalar.empty() == ((type & KEY) == 0));
        // key tag cannot be empty
        RYML_ASSERT(key.tag.empty() == ((type & KEYTAG) == 0));
        // val may be empty even though VAL is set. But when VAL is not set, val must be empty
        RYML_ASSERT(((type & VAL) != 0) || val.scalar.empty());
        // val tag cannot be empty
        RYML_ASSERT(val.tag.empty() == ((type & VALTAG) == 0));
        return true;
    }
};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** contains the data for each YAML node. */
struct NodeData
{
    NodeType   m_type;

    NodeScalar m_key;
    NodeScalar m_val;

    size_t     m_parent;
    size_t     m_first_child;
    size_t     m_last_child;
    size_t     m_next_sibling;
    size_t     m_prev_sibling;
};
C4_MUST_BE_TRIVIAL_COPY(NodeData);


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

class RYML_EXPORT Tree
{
public:

    /** @name construction and assignment */
    /** @{ */

    Tree() : Tree(get_callbacks()) {}
    Tree(Callbacks const& cb);
    Tree(size_t node_capacity, size_t arena_capacity=0) : Tree(node_capacity, arena_capacity, get_callbacks()) {}
    Tree(size_t node_capacity, size_t arena_capacity, Callbacks const& cb);

    ~Tree();

    Tree(Tree const& that) noexcept;
    Tree(Tree     && that) noexcept;

    Tree& operator= (Tree const& that) noexcept;
    Tree& operator= (Tree     && that) noexcept;

    /** @} */

public:

    /** @name memory and sizing */
    /** @{ */

    void reserve(size_t node_capacity);

    /** clear the tree and zero every node
     * @note does NOT clear the arena
     * @see clear_arena() */
    void clear();
    inline void clear_arena() { m_arena_pos = 0; }

    inline bool   empty() const { return m_size == 0; }

    inline size_t size() const { return m_size; }
    inline size_t capacity() const { return m_cap; }
    inline size_t slack() const { RYML_ASSERT(m_cap >= m_size); return m_cap - m_size; }

    Callbacks const& callbacks() const { return m_callbacks; }
    void callbacks(Callbacks const& cb) { m_callbacks = cb; }

    /** @} */

public:

    /** @name node getters */
    /** @{ */

    //! get the index of a node belonging to this tree.
    //! @p n can be nullptr, in which case a
    size_t id(NodeData const* n) const
    {
        if( ! n)
        {
            return NONE;
        }
        RYML_ASSERT(n >= m_buf && n < m_buf + m_cap);
        return static_cast<size_t>(n - m_buf);
    }

    //! get a pointer to a node's NodeData.
    //! i can be NONE, in which case a nullptr is returned
    inline NodeData *get(size_t i)
    {
        if(i == NONE)
            return nullptr;
        RYML_ASSERT(i >= 0 && i < m_cap);
        return m_buf + i;
    }
    //! get a pointer to a node's NodeData.
    //! i can be NONE, in which case a nullptr is returned.
    inline NodeData const *get(size_t i) const
    {
        if(i == NONE)
            return nullptr;
        RYML_ASSERT(i >= 0 && i < m_cap);
        return m_buf + i;
    }

    //! An if-less form of get() that demands a valid node index.
    //! This function is implementation only; use at your own risk.
    inline NodeData       * _p(size_t i)       { RYML_ASSERT(i != NONE && i >= 0 && i < m_cap); return m_buf + i; }
    //! An if-less form of get() that demands a valid node index.
    //! This function is implementation only; use at your own risk.
    inline NodeData const * _p(size_t i) const { RYML_ASSERT(i != NONE && i >= 0 && i < m_cap); return m_buf + i; }

    //! Get the id of the root node
    size_t root_id()       { if(m_cap == 0) { reserve(16); } RYML_ASSERT(m_cap > 0 && m_size > 0); return 0; }
    //! Get the id of the root node
    size_t root_id() const {                                 RYML_ASSERT(m_cap > 0 && m_size > 0); return 0; }

    //! Get a NodeRef of a node by id
    NodeRef      ref(size_t id);
    //! Get a NodeRef of a node by id
    ConstNodeRef ref(size_t id) const;
    //! Get a NodeRef of a node by id
    ConstNodeRef cref(size_t id);
    //! Get a NodeRef of a node by id
    ConstNodeRef cref(size_t id) const;

    //! Get the root as a NodeRef
    NodeRef      rootref();
    //! Get the root as a NodeRef
    ConstNodeRef rootref() const;
    //! Get the root as a NodeRef
    ConstNodeRef crootref();
    //! Get the root as a NodeRef
    ConstNodeRef crootref() const;

    //! find a root child by name, return it as a NodeRef
    //! @note requires the root to be a map.
    NodeRef      operator[] (csubstr key);
    //! find a root child by name, return it as a NodeRef
    //! @note requires the root to be a map.
    ConstNodeRef operator[] (csubstr key) const;

    //! find a root child by index: return the root node's @p i-th child as a NodeRef
    //! @note @i is NOT the node id, but the child's position
    NodeRef      operator[] (size_t i);
    //! find a root child by index: return the root node's @p i-th child as a NodeRef
    //! @note @i is NOT the node id, but the child's position
    ConstNodeRef operator[] (size_t i) const;

    //! get the i-th document of the stream
    //! @note @i is NOT the node id, but the doc position within the stream
    NodeRef      docref(size_t i);
    //! get the i-th document of the stream
    //! @note @i is NOT the node id, but the doc position within the stream
    ConstNodeRef docref(size_t i) const;

    /** @} */

public:

    /** @name node property getters */
    /** @{ */

    NodeType type(size_t node) const { return _p(node)->m_type; }
    const char* type_str(size_t node) const { return NodeType::type_str(_p(node)->m_type); }

    csubstr    const& key       (size_t node) const { RYML_ASSERT(has_key(node)); return _p(node)->m_key.scalar; }
    csubstr    const& key_tag   (size_t node) const { RYML_ASSERT(has_key_tag(node)); return _p(node)->m_key.tag; }
    csubstr    const& key_ref   (size_t node) const { RYML_ASSERT(is_key_ref(node) && ! has_key_anchor(node)); return _p(node)->m_key.anchor; }
    csubstr    const& key_anchor(size_t node) const { RYML_ASSERT( ! is_key_ref(node) && has_key_anchor(node)); return _p(node)->m_key.anchor; }
    NodeScalar const& keysc     (size_t node) const { RYML_ASSERT(has_key(node)); return _p(node)->m_key; }

    csubstr    const& val       (size_t node) const { RYML_ASSERT(has_val(node)); return _p(node)->m_val.scalar; }
    csubstr    const& val_tag   (size_t node) const { RYML_ASSERT(has_val_tag(node)); return _p(node)->m_val.tag; }
    csubstr    const& val_ref   (size_t node) const { RYML_ASSERT(is_val_ref(node) && ! has_val_anchor(node)); return _p(node)->m_val.anchor; }
    csubstr    const& val_anchor(size_t node) const { RYML_ASSERT( ! is_val_ref(node) && has_val_anchor(node)); return _p(node)->m_val.anchor; }
    NodeScalar const& valsc     (size_t node) const { RYML_ASSERT(has_val(node)); return _p(node)->m_val; }

    /** @} */

public:

    /** @name node predicates */
    /** @{ */

    C4_ALWAYS_INLINE bool is_stream(size_t node) const { return _p(node)->m_type.is_stream(); }
    C4_ALWAYS_INLINE bool is_doc(size_t node) const { return _p(node)->m_type.is_doc(); }
    C4_ALWAYS_INLINE bool is_container(size_t node) const { return _p(node)->m_type.is_container(); }
    C4_ALWAYS_INLINE bool is_map(size_t node) const { return _p(node)->m_type.is_map(); }
    C4_ALWAYS_INLINE bool is_seq(size_t node) const { return _p(node)->m_type.is_seq(); }
    C4_ALWAYS_INLINE bool has_key(size_t node) const { return _p(node)->m_type.has_key(); }
    C4_ALWAYS_INLINE bool has_val(size_t node) const { return _p(node)->m_type.has_val(); }
    C4_ALWAYS_INLINE bool is_val(size_t node) const { return _p(node)->m_type.is_val(); }
    C4_ALWAYS_INLINE bool is_keyval(size_t node) const { return _p(node)->m_type.is_keyval(); }
    C4_ALWAYS_INLINE bool has_key_tag(size_t node) const { return _p(node)->m_type.has_key_tag(); }
    C4_ALWAYS_INLINE bool has_val_tag(size_t node) const { return _p(node)->m_type.has_val_tag(); }
    C4_ALWAYS_INLINE bool has_key_anchor(size_t node) const { return _p(node)->m_type.has_key_anchor(); }
    C4_ALWAYS_INLINE bool is_key_anchor(size_t node) const { return _p(node)->m_type.is_key_anchor(); }
    C4_ALWAYS_INLINE bool has_val_anchor(size_t node) const { return _p(node)->m_type.has_val_anchor(); }
    C4_ALWAYS_INLINE bool is_val_anchor(size_t node) const { return _p(node)->m_type.is_val_anchor(); }
    C4_ALWAYS_INLINE bool has_anchor(size_t node) const { return _p(node)->m_type.has_anchor(); }
    C4_ALWAYS_INLINE bool is_anchor(size_t node) const { return _p(node)->m_type.is_anchor(); }
    C4_ALWAYS_INLINE bool is_key_ref(size_t node) const { return _p(node)->m_type.is_key_ref(); }
    C4_ALWAYS_INLINE bool is_val_ref(size_t node) const { return _p(node)->m_type.is_val_ref(); }
    C4_ALWAYS_INLINE bool is_ref(size_t node) const { return _p(node)->m_type.is_ref(); }
    C4_ALWAYS_INLINE bool is_anchor_or_ref(size_t node) const { return _p(node)->m_type.is_anchor_or_ref(); }
    C4_ALWAYS_INLINE bool is_key_quoted(size_t node) const { return _p(node)->m_type.is_key_quoted(); }
    C4_ALWAYS_INLINE bool is_val_quoted(size_t node) const { return _p(node)->m_type.is_val_quoted(); }
    C4_ALWAYS_INLINE bool is_quoted(size_t node) const { return _p(node)->m_type.is_quoted(); }

    C4_ALWAYS_INLINE bool parent_is_seq(size_t node) const { RYML_ASSERT(has_parent(node)); return is_seq(_p(node)->m_parent); }
    C4_ALWAYS_INLINE bool parent_is_map(size_t node) const { RYML_ASSERT(has_parent(node)); return is_map(_p(node)->m_parent); }

    /** true when key and val are empty, and has no children */
    C4_ALWAYS_INLINE bool empty(size_t node) const { return ! has_children(node) && _p(node)->m_key.empty() && (( ! (_p(node)->m_type & VAL)) || _p(node)->m_val.empty()); }
    /** true when the node has an anchor named a */
    C4_ALWAYS_INLINE bool has_anchor(size_t node, csubstr a) const { return _p(node)->m_key.anchor == a || _p(node)->m_val.anchor == a; }

    C4_ALWAYS_INLINE bool key_is_null(size_t node) const { RYML_ASSERT(has_key(node)); NodeData const* C4_RESTRICT n = _p(node); return !n->m_type.is_key_quoted() && _is_null(n->m_key.scalar); }
    C4_ALWAYS_INLINE bool val_is_null(size_t node) const { RYML_ASSERT(has_val(node)); NodeData const* C4_RESTRICT n = _p(node); return !n->m_type.is_val_quoted() && _is_null(n->m_val.scalar); }
    static bool _is_null(csubstr s) noexcept
    {
        return s.str == nullptr ||
            s == "~" ||
            s == "null" ||
            s == "Null" ||
            s == "NULL";
    }

    /** @} */

public:

    /** @name hierarchy predicates */
    /** @{ */

    bool is_root(size_t node) const { RYML_ASSERT(_p(node)->m_parent != NONE || node == 0); return _p(node)->m_parent == NONE; }

    bool has_parent(size_t node) const { return _p(node)->m_parent != NONE; }

    /** true if @p node has a child with id @p ch */
    bool has_child(size_t node, size_t ch) const { return _p(ch)->m_parent == node; }
    /** true if @p node has a child with key @p key */
    bool has_child(size_t node, csubstr key) const { return find_child(node, key) != npos; }
    /** true if @p node has any children key */
    bool has_children(size_t node) const { return _p(node)->m_first_child != NONE; }

    /** true if @p node has a sibling with id @p sib */
    bool has_sibling(size_t node, size_t sib) const { return _p(node)->m_parent == _p(sib)->m_parent; }
    /** true if one of the node's siblings has the given key */
    bool has_sibling(size_t node, csubstr key) const { return find_sibling(node, key) != npos; }
    /** true if node is not a single child */
    bool has_other_siblings(size_t node) const
    {
        NodeData const *n = _p(node);
        if(C4_LIKELY(n->m_parent != NONE))
        {
            n = _p(n->m_parent);
            return n->m_first_child != n->m_last_child;
        }
        return false;
    }

    RYML_DEPRECATED("use has_other_siblings()") bool has_siblings(size_t /*node*/) const { return true; }

    /** @} */

public:

    /** @name hierarchy getters */
    /** @{ */

    size_t parent(size_t node) const { return _p(node)->m_parent; }

    size_t prev_sibling(size_t node) const { return _p(node)->m_prev_sibling; }
    size_t next_sibling(size_t node) const { return _p(node)->m_next_sibling; }

    /** O(#num_children) */
    size_t num_children(size_t node) const;
    size_t child_pos(size_t node, size_t ch) const;
    size_t first_child(size_t node) const { return _p(node)->m_first_child; }
    size_t last_child(size_t node) const { return _p(node)->m_last_child; }
    size_t child(size_t node, size_t pos) const;
    size_t find_child(size_t node, csubstr const& key) const;

    /** O(#num_siblings) */
    /** counts with this */
    size_t num_siblings(size_t node) const { return is_root(node) ? 1 : num_children(_p(node)->m_parent); }
    /** does not count with this */
    size_t num_other_siblings(size_t node) const { size_t ns = num_siblings(node); RYML_ASSERT(ns > 0); return ns-1; }
    size_t sibling_pos(size_t node, size_t sib) const { RYML_ASSERT( ! is_root(node) || node == root_id()); return child_pos(_p(node)->m_parent, sib); }
    size_t first_sibling(size_t node) const { return is_root(node) ? node : _p(_p(node)->m_parent)->m_first_child; }
    size_t last_sibling(size_t node) const { return is_root(node) ? node : _p(_p(node)->m_parent)->m_last_child; }
    size_t sibling(size_t node, size_t pos) const { return child(_p(node)->m_parent, pos); }
    size_t find_sibling(size_t node, csubstr const& key) const { return find_child(_p(node)->m_parent, key); }

    size_t doc(size_t i) const { size_t rid = root_id(); RYML_ASSERT(is_stream(rid)); return child(rid, i); } //!< gets the @p i document node index. requires that the root node is a stream.

    /** @} */

public:

    /** @name node modifiers */
    /** @{ */

    void to_keyval(size_t node, csubstr key, csubstr val, type_bits more_flags=0);
    void to_map(size_t node, csubstr key, type_bits more_flags=0);
    void to_seq(size_t node, csubstr key, type_bits more_flags=0);
    void to_val(size_t node, csubstr val, type_bits more_flags=0);
    void to_map(size_t node, type_bits more_flags=0);
    void to_seq(size_t node, type_bits more_flags=0);
    void to_doc(size_t node, type_bits more_flags=0);
    void to_stream(size_t node, type_bits more_flags=0);

    void set_key(size_t node, csubstr key) { RYML_ASSERT(has_key(node)); _p(node)->m_key.scalar = key; }
    void set_val(size_t node, csubstr val) { RYML_ASSERT(has_val(node)); _p(node)->m_val.scalar = val; }

    void set_key_tag(size_t node, csubstr tag) { RYML_ASSERT(has_key(node)); _p(node)->m_key.tag = tag; _add_flags(node, KEYTAG); }
    void set_val_tag(size_t node, csubstr tag) { RYML_ASSERT(has_val(node) || is_container(node)); _p(node)->m_val.tag = tag; _add_flags(node, VALTAG); }

    void set_key_anchor(size_t node, csubstr anchor) { RYML_ASSERT( ! is_key_ref(node)); _p(node)->m_key.anchor = anchor.triml('&'); _add_flags(node, KEYANCH); }
    void set_val_anchor(size_t node, csubstr anchor) { RYML_ASSERT( ! is_val_ref(node)); _p(node)->m_val.anchor = anchor.triml('&'); _add_flags(node, VALANCH); }
    void set_key_ref   (size_t node, csubstr ref   ) { RYML_ASSERT( ! has_key_anchor(node)); NodeData* C4_RESTRICT n = _p(node); n->m_key.set_ref_maybe_replacing_scalar(ref, n->m_type.has_key()); _add_flags(node, KEY|KEYREF); }
    void set_val_ref   (size_t node, csubstr ref   ) { RYML_ASSERT( ! has_val_anchor(node)); NodeData* C4_RESTRICT n = _p(node); n->m_val.set_ref_maybe_replacing_scalar(ref, n->m_type.has_val()); _add_flags(node, VAL|VALREF); }

    void rem_key_anchor(size_t node) { _p(node)->m_key.anchor.clear(); _rem_flags(node, KEYANCH); }
    void rem_val_anchor(size_t node) { _p(node)->m_val.anchor.clear(); _rem_flags(node, VALANCH); }
    void rem_key_ref   (size_t node) { _p(node)->m_key.anchor.clear(); _rem_flags(node, KEYREF); }
    void rem_val_ref   (size_t node) { _p(node)->m_val.anchor.clear(); _rem_flags(node, VALREF); }
    void rem_anchor_ref(size_t node) { _p(node)->m_key.anchor.clear(); _p(node)->m_val.anchor.clear(); _rem_flags(node, KEYANCH|VALANCH|KEYREF|VALREF); }

    /** @} */

public:

    /** @name tree modifiers */
    /** @{ */

    /** reorder the tree in memory so that all the nodes are stored
     * in a linear sequence when visited in depth-first order.
     * This will invalidate existing ids, since the node id is its
     * position in the node array. */
    void reorder();

    /** Resolve references (aliases <- anchors) in the tree.
     *
     * Dereferencing is opt-in; after parsing, Tree::resolve()
     * has to be called explicitly for obtaining resolved references in the
     * tree. This method will resolve all references and substitute the
     * anchored values in place of the reference.
     *
     * This method first does a full traversal of the tree to gather all
     * anchors and references in a separate collection, then it goes through
     * that collection to locate the names, which it does by obeying the YAML
     * standard diktat that "an alias node refers to the most recent node in
     * the serialization having the specified anchor"
     *
     * So, depending on the number of anchor/alias nodes, this is a
     * potentially expensive operation, with a best-case linear complexity
     * (from the initial traversal). This potential cost is the reason for
     * requiring an explicit call.
     */
    void resolve();

    /** @} */

public:

    /** @name tag directives */
    /** @{ */

    void resolve_tags();

    size_t num_tag_directives() const;
    size_t add_tag_directive(TagDirective const& td);
    void clear_tag_directives();

    size_t resolve_tag(substr output, csubstr tag, size_t node_id) const;
    csubstr resolve_tag_sub(substr output, csubstr tag, size_t node_id) const
    {
        size_t needed = resolve_tag(output, tag, node_id);
        return needed <= output.len ? output.first(needed) : output;
    }

    using tag_directive_const_iterator = TagDirective const*;
    tag_directive_const_iterator begin_tag_directives() const { return m_tag_directives; }
    tag_directive_const_iterator end_tag_directives() const { return m_tag_directives + num_tag_directives(); }

    struct TagDirectiveProxy
    {
        tag_directive_const_iterator b, e;
        tag_directive_const_iterator begin() const { return b; }
        tag_directive_const_iterator end() const { return e; }
    };

    TagDirectiveProxy tag_directives() const { return TagDirectiveProxy{begin_tag_directives(), end_tag_directives()}; }

    /** @} */

public:

    /** @name modifying hierarchy */
    /** @{ */

    /** create and insert a new child of @p parent. insert after the (to-be)
     * sibling @p after, which must be a child of @p parent. To insert as the
     * first child, set after to NONE */
    C4_ALWAYS_INLINE size_t insert_child(size_t parent, size_t after)
    {
        RYML_ASSERT(parent != NONE);
        RYML_ASSERT(is_container(parent) || is_root(parent));
        RYML_ASSERT(after == NONE || (_p(after)->m_parent == parent));
        size_t child = _claim();
        _set_hierarchy(child, parent, after);
        return child;
    }
    /** create and insert a node as the first child of @p parent */
    C4_ALWAYS_INLINE size_t prepend_child(size_t parent) { return insert_child(parent, NONE); }
    /** create and insert a node as the last child of @p parent */
    C4_ALWAYS_INLINE size_t  append_child(size_t parent) { return insert_child(parent, _p(parent)->m_last_child); }

public:

    #if defined(__clang__)
    #   pragma clang diagnostic push
    #   pragma clang diagnostic ignored "-Wnull-dereference"
    #elif defined(__GNUC__)
    #   pragma GCC diagnostic push
    #   if __GNUC__ >= 6
    #       pragma GCC diagnostic ignored "-Wnull-dereference"
    #   endif
    #endif

    //! create and insert a new sibling of n. insert after "after"
    C4_ALWAYS_INLINE size_t insert_sibling(size_t node, size_t after)
    {
        return insert_child(_p(node)->m_parent, after);
    }
    /** create and insert a node as the first node of @p parent */
    C4_ALWAYS_INLINE size_t prepend_sibling(size_t node) { return prepend_child(_p(node)->m_parent); }
    C4_ALWAYS_INLINE size_t  append_sibling(size_t node) { return append_child(_p(node)->m_parent); }

public:

    /** remove an entire branch at once: ie remove the children and the node itself */
    inline void remove(size_t node)
    {
        remove_children(node);
        _release(node);
    }

    /** remove all the node's children, but keep the node itself */
    void remove_children(size_t node);

    /** change the @p type of the node to one of MAP, SEQ or VAL.  @p
     * type must have one and only one of MAP,SEQ,VAL; @p type may
     * possibly have KEY, but if it does, then the @p node must also
     * have KEY. Changing to the same type is a no-op. Otherwise,
     * changing to a different type will initialize the node with an
     * empty value of the desired type: changing to VAL will
     * initialize with a null scalar (~), changing to MAP will
     * initialize with an empty map ({}), and changing to SEQ will
     * initialize with an empty seq ([]). */
    bool change_type(size_t node, NodeType type);

    bool change_type(size_t node, type_bits type)
    {
        return change_type(node, (NodeType)type);
    }

    #if defined(__clang__)
    #   pragma clang diagnostic pop
    #elif defined(__GNUC__)
    #   pragma GCC diagnostic pop
    #endif

public:

    /** change the node's position in the parent */
    void move(size_t node, size_t after);

    /** change the node's parent and position */
    void move(size_t node, size_t new_parent, size_t after);

    /** change the node's parent and position to a different tree
     * @return the index of the new node in the destination tree */
    size_t move(Tree * src, size_t node, size_t new_parent, size_t after);

    /** ensure the first node is a stream. Eg, change this tree
     *
     *  DOCMAP
     *    MAP
     *      KEYVAL
     *      KEYVAL
     *    SEQ
     *      VAL
     *
     * to
     *
     *  STREAM
     *    DOCMAP
     *      MAP
     *        KEYVAL
     *        KEYVAL
     *      SEQ
     *        VAL
     *
     * If the root is already a stream, this is a no-op.
     */
    void set_root_as_stream();

public:

    /** recursively duplicate a node from this tree into a new parent,
     * placing it after one of its children
     * @return the index of the copy */
    size_t duplicate(size_t node, size_t new_parent, size_t after);
    /** recursively duplicate a node from a different tree into a new parent,
     * placing it after one of its children
     * @return the index of the copy */
    size_t duplicate(Tree const* src, size_t node, size_t new_parent, size_t after);

    /** recursively duplicate the node's children (but not the node)
     * @return the index of the last duplicated child */
    size_t duplicate_children(size_t node, size_t parent, size_t after);
    /** recursively duplicate the node's children (but not the node), where
     * the node is from a different tree
     * @return the index of the last duplicated child */
    size_t duplicate_children(Tree const* src, size_t node, size_t parent, size_t after);

    void duplicate_contents(size_t node, size_t where);
    void duplicate_contents(Tree const* src, size_t node, size_t where);

    /** duplicate the node's children (but not the node) in a new parent, but
     * omit repetitions where a duplicated node has the same key (in maps) or
     * value (in seqs). If one of the duplicated children has the same key
     * (in maps) or value (in seqs) as one of the parent's children, the one
     * that is placed closest to the end will prevail. */
    size_t duplicate_children_no_rep(size_t node, size_t parent, size_t after);
    size_t duplicate_children_no_rep(Tree const* src, size_t node, size_t parent, size_t after);

public:

    void merge_with(Tree const* src, size_t src_node=NONE, size_t dst_root=NONE);

    /** @} */

public:

    /** @name internal string arena */
    /** @{ */

    /** get the current size of the tree's internal arena */
    RYML_DEPRECATED("use arena_size() instead") size_t arena_pos() const { return m_arena_pos; }
    /** get the current size of the tree's internal arena */
    inline size_t arena_size() const { return m_arena_pos; }
    /** get the current capacity of the tree's internal arena */
    inline size_t arena_capacity() const { return m_arena.len; }
    /** get the current slack of the tree's internal arena */
    inline size_t arena_slack() const { RYML_ASSERT(m_arena.len >= m_arena_pos); return m_arena.len - m_arena_pos; }

    /** get the current arena */
    substr arena() const { return m_arena.first(m_arena_pos); }

    /** return true if the given substring is part of the tree's string arena */
    bool in_arena(csubstr s) const
    {
        return m_arena.is_super(s);
    }

    /** serialize the given floating-point variable to the tree's
     * arena, growing it as needed to accomodate the serialization.
     *
     * @note Growing the arena may cause relocation of the entire
     * existing arena, and thus change the contents of individual
     * nodes, and thus cost O(numnodes)+O(arenasize). To avoid this
     * cost, ensure that the arena is reserved to an appropriate size
     * using .reserve_arena()
     *
     * @see alloc_arena() */
    template<class T>
    typename std::enable_if<std::is_floating_point<T>::value, csubstr>::type
    to_arena(T const& C4_RESTRICT a)
    {
        substr rem(m_arena.sub(m_arena_pos));
        size_t num = to_chars_float(rem, a);
        if(num > rem.len)
        {
            rem = _grow_arena(num);
            num = to_chars_float(rem, a);
            RYML_ASSERT(num <= rem.len);
        }
        rem = _request_span(num);
        return rem;
    }

    /** serialize the given non-floating-point variable to the tree's
     * arena, growing it as needed to accomodate the serialization.
     *
     * @note Growing the arena may cause relocation of the entire
     * existing arena, and thus change the contents of individual
     * nodes, and thus cost O(numnodes)+O(arenasize). To avoid this
     * cost, ensure that the arena is reserved to an appropriate size
     * using .reserve_arena()
     *
     * @see alloc_arena() */
    template<class T>
    typename std::enable_if<!std::is_floating_point<T>::value, csubstr>::type
    to_arena(T const& C4_RESTRICT a)
    {
        substr rem(m_arena.sub(m_arena_pos));
        size_t num = to_chars(rem, a);
        if(num > rem.len)
        {
            rem = _grow_arena(num);
            num = to_chars(rem, a);
            RYML_ASSERT(num <= rem.len);
        }
        rem = _request_span(num);
        return rem;
    }

    /** serialize the given csubstr to the tree's arena, growing the
     * arena as needed to accomodate the serialization.
     *
     * @note Growing the arena may cause relocation of the entire
     * existing arena, and thus change the contents of individual
     * nodes, and thus cost O(numnodes)+O(arenasize). To avoid this
     * cost, ensure that the arena is reserved to an appropriate size
     * using .reserve_arena()
     *
     * @see alloc_arena() */
    csubstr to_arena(csubstr a)
    {
        if(a.len > 0)
        {
            substr rem(m_arena.sub(m_arena_pos));
            size_t num = to_chars(rem, a);
            if(num > rem.len)
            {
                rem = _grow_arena(num);
                num = to_chars(rem, a);
                RYML_ASSERT(num <= rem.len);
            }
            return _request_span(num);
        }
        else
        {
            if(a.str == nullptr)
            {
                return csubstr{};
            }
            else if(m_arena.str == nullptr)
            {
                // Arena is empty and we want to store a non-null
                // zero-length string.
                // Even though the string has zero length, we need
                // some "memory" to store a non-nullptr string
                _grow_arena(1);
            }
            return _request_span(0);
        }
    }
    C4_ALWAYS_INLINE csubstr to_arena(const char *s)
    {
        return to_arena(to_csubstr(s));
    }
    C4_ALWAYS_INLINE csubstr to_arena(std::nullptr_t)
    {
        return csubstr{};
    }

    /** copy the given substr to the tree's arena, growing it by the
     * required size
     *
     * @note Growing the arena may cause relocation of the entire
     * existing arena, and thus change the contents of individual
     * nodes, and thus cost O(numnodes)+O(arenasize). To avoid this
     * cost, ensure that the arena is reserved to an appropriate size
     * using .reserve_arena()
     *
     * @see alloc_arena() */
    substr copy_to_arena(csubstr s)
    {
        substr cp = alloc_arena(s.len);
        RYML_ASSERT(cp.len == s.len);
        RYML_ASSERT(!s.overlaps(cp));
        #if (!defined(__clang__)) && (defined(__GNUC__) && __GNUC__ >= 10)
        C4_SUPPRESS_WARNING_GCC_PUSH
        C4_SUPPRESS_WARNING_GCC("-Wstringop-overflow=") // no need for terminating \0
        C4_SUPPRESS_WARNING_GCC( "-Wrestrict") // there's an assert to ensure no violation of restrict behavior
        #endif
        if(s.len)
            memcpy(cp.str, s.str, s.len);
        #if (!defined(__clang__)) && (defined(__GNUC__) && __GNUC__ >= 10)
        C4_SUPPRESS_WARNING_GCC_POP
        #endif
        return cp;
    }

    /** grow the tree's string arena by the given size and return a substr
     * of the added portion
     *
     * @note Growing the arena may cause relocation of the entire
     * existing arena, and thus change the contents of individual
     * nodes, and thus cost O(numnodes)+O(arenasize). To avoid this
     * cost, ensure that the arena is reserved to an appropriate size
     * using .reserve_arena().
     *
     * @see reserve_arena() */
    substr alloc_arena(size_t sz)
    {
        if(sz > arena_slack())
            _grow_arena(sz - arena_slack());
        substr s = _request_span(sz);
        return s;
    }

    /** ensure the tree's internal string arena is at least the given capacity
     * @note This operation has a potential complexity of O(numNodes)+O(arenasize).
     * Growing the arena may cause relocation of the entire
     * existing arena, and thus change the contents of individual nodes. */
    void reserve_arena(size_t arena_cap)
    {
        if(arena_cap > m_arena.len)
        {
            substr buf;
            buf.str = (char*) m_callbacks.m_allocate(arena_cap, m_arena.str, m_callbacks.m_user_data);
            buf.len = arena_cap;
            if(m_arena.str)
            {
                RYML_ASSERT(m_arena.len >= 0);
                _relocate(buf); // does a memcpy and changes nodes using the arena
                m_callbacks.m_free(m_arena.str, m_arena.len, m_callbacks.m_user_data);
            }
            m_arena = buf;
        }
    }

    /** @} */

private:

    substr _grow_arena(size_t more)
    {
        size_t cap = m_arena.len + more;
        cap = cap < 2 * m_arena.len ? 2 * m_arena.len : cap;
        cap = cap < 64 ? 64 : cap;
        reserve_arena(cap);
        return m_arena.sub(m_arena_pos);
    }

    substr _request_span(size_t sz)
    {
        substr s;
        s = m_arena.sub(m_arena_pos, sz);
        m_arena_pos += sz;
        return s;
    }

    substr _relocated(csubstr s, substr next_arena) const
    {
        RYML_ASSERT(m_arena.is_super(s));
        RYML_ASSERT(m_arena.sub(0, m_arena_pos).is_super(s));
        auto pos = (s.str - m_arena.str);
        substr r(next_arena.str + pos, s.len);
        RYML_ASSERT(r.str - next_arena.str == pos);
        RYML_ASSERT(next_arena.sub(0, m_arena_pos).is_super(r));
        return r;
    }

public:

    /** @name lookup */
    /** @{ */

    struct lookup_result
    {
        size_t  target;
        size_t  closest;
        size_t  path_pos;
        csubstr path;

        inline operator bool() const { return target != NONE; }

        lookup_result() : target(NONE), closest(NONE), path_pos(0), path() {}
        lookup_result(csubstr path_, size_t start) : target(NONE), closest(start), path_pos(0), path(path_) {}

        /** get the part ot the input path that was resolved */
        csubstr resolved() const;
        /** get the part ot the input path that was unresolved */
        csubstr unresolved() const;
    };

    /** for example foo.bar[0].baz */
    lookup_result lookup_path(csubstr path, size_t start=NONE) const;

    /** defaulted lookup: lookup @p path; if the lookup fails, recursively modify
     * the tree so that the corresponding lookup_path() would return the
     * default value.
     * @see lookup_path() */
    size_t lookup_path_or_modify(csubstr default_value, csubstr path, size_t start=NONE);

    /** defaulted lookup: lookup @p path; if the lookup fails, recursively modify
     * the tree so that the corresponding lookup_path() would return the
     * branch @p src_node (from the tree @p src).
     * @see lookup_path() */
    size_t lookup_path_or_modify(Tree const *src, size_t src_node, csubstr path, size_t start=NONE);

    /** @} */

private:

    struct _lookup_path_token
    {
        csubstr value;
        NodeType type;
        _lookup_path_token() : value(), type() {}
        _lookup_path_token(csubstr v, NodeType t) : value(v), type(t) {}
        inline operator bool() const { return type != NOTYPE; }
        bool is_index() const { return value.begins_with('[') && value.ends_with(']'); }
    };

    size_t _lookup_path_or_create(csubstr path, size_t start);

    void   _lookup_path       (lookup_result *r) const;
    void   _lookup_path_modify(lookup_result *r);

    size_t _next_node       (lookup_result *r, _lookup_path_token *parent) const;
    size_t _next_node_modify(lookup_result *r, _lookup_path_token *parent);

    void   _advance(lookup_result *r, size_t more) const;

    _lookup_path_token _next_token(lookup_result *r, _lookup_path_token const& parent) const;

private:

    void _clear();
    void _free();
    void _copy(Tree const& that);
    void _move(Tree      & that);

    void _relocate(substr next_arena);

public:

    #if ! RYML_USE_ASSERT
    C4_ALWAYS_INLINE void _check_next_flags(size_t, type_bits) {}
    #else
    void _check_next_flags(size_t node, type_bits f)
    {
        auto n = _p(node);
        type_bits o = n->m_type; // old
        C4_UNUSED(o);
        if(f & MAP)
        {
            RYML_ASSERT_MSG((f & SEQ) == 0, "cannot mark simultaneously as map and seq");
            RYML_ASSERT_MSG((f & VAL) == 0, "cannot mark simultaneously as map and val");
            RYML_ASSERT_MSG((o & SEQ) == 0, "cannot turn a seq into a map; clear first");
            RYML_ASSERT_MSG((o & VAL) == 0, "cannot turn a val into a map; clear first");
        }
        else if(f & SEQ)
        {
            RYML_ASSERT_MSG((f & MAP) == 0, "cannot mark simultaneously as seq and map");
            RYML_ASSERT_MSG((f & VAL) == 0, "cannot mark simultaneously as seq and val");
            RYML_ASSERT_MSG((o & MAP) == 0, "cannot turn a map into a seq; clear first");
            RYML_ASSERT_MSG((o & VAL) == 0, "cannot turn a val into a seq; clear first");
        }
        if(f & KEY)
        {
            RYML_ASSERT(!is_root(node));
            auto pid = parent(node); C4_UNUSED(pid);
            RYML_ASSERT(is_map(pid));
        }
        if((f & VAL) && !is_root(node))
        {
            auto pid = parent(node); C4_UNUSED(pid);
            RYML_ASSERT(is_map(pid) || is_seq(pid));
        }
    }
    #endif

    inline void _set_flags(size_t node, NodeType_e f) { _check_next_flags(node, f); _p(node)->m_type = f; }
    inline void _set_flags(size_t node, type_bits  f) { _check_next_flags(node, f); _p(node)->m_type = f; }

    inline void _add_flags(size_t node, NodeType_e f) { NodeData *d = _p(node); type_bits fb = f |  d->m_type; _check_next_flags(node, fb); d->m_type = (NodeType_e) fb; }
    inline void _add_flags(size_t node, type_bits  f) { NodeData *d = _p(node);                f |= d->m_type; _check_next_flags(node,  f); d->m_type = f; }

    inline void _rem_flags(size_t node, NodeType_e f) { NodeData *d = _p(node); type_bits fb = d->m_type & ~f; _check_next_flags(node, fb); d->m_type = (NodeType_e) fb; }
    inline void _rem_flags(size_t node, type_bits  f) { NodeData *d = _p(node);            f = d->m_type & ~f; _check_next_flags(node,  f); d->m_type = f; }

    void _set_key(size_t node, csubstr key, type_bits more_flags=0)
    {
        _p(node)->m_key.scalar = key;
        _add_flags(node, KEY|more_flags);
    }
    void _set_key(size_t node, NodeScalar const& key, type_bits more_flags=0)
    {
        _p(node)->m_key = key;
        _add_flags(node, KEY|more_flags);
    }

    void _set_val(size_t node, csubstr val, type_bits more_flags=0)
    {
        RYML_ASSERT(num_children(node) == 0);
        RYML_ASSERT(!is_seq(node) && !is_map(node));
        _p(node)->m_val.scalar = val;
        _add_flags(node, VAL|more_flags);
    }
    void _set_val(size_t node, NodeScalar const& val, type_bits more_flags=0)
    {
        RYML_ASSERT(num_children(node) == 0);
        RYML_ASSERT( ! is_container(node));
        _p(node)->m_val = val;
        _add_flags(node, VAL|more_flags);
    }

    void _set(size_t node, NodeInit const& i)
    {
        RYML_ASSERT(i._check());
        NodeData *n = _p(node);
        RYML_ASSERT(n->m_key.scalar.empty() || i.key.scalar.empty() || i.key.scalar == n->m_key.scalar);
        _add_flags(node, i.type);
        if(n->m_key.scalar.empty())
        {
            if( ! i.key.scalar.empty())
            {
                _set_key(node, i.key.scalar);
            }
        }
        n->m_key.tag = i.key.tag;
        n->m_val = i.val;
    }

    void _set_parent_as_container_if_needed(size_t in)
    {
        NodeData const* n = _p(in);
        size_t ip = parent(in);
        if(ip != NONE)
        {
            if( ! (is_seq(ip) || is_map(ip)))
            {
                if((in == first_child(ip)) && (in == last_child(ip)))
                {
                    if( ! n->m_key.empty() || has_key(in))
                    {
                        _add_flags(ip, MAP);
                    }
                    else
                    {
                        _add_flags(ip, SEQ);
                    }
                }
            }
        }
    }

    void _seq2map(size_t node)
    {
        RYML_ASSERT(is_seq(node));
        for(size_t i = first_child(node); i != NONE; i = next_sibling(i))
        {
            NodeData *C4_RESTRICT ch = _p(i);
            if(ch->m_type.is_keyval())
                continue;
            ch->m_type.add(KEY);
            ch->m_key = ch->m_val;
        }
        auto *C4_RESTRICT n = _p(node);
        n->m_type.rem(SEQ);
        n->m_type.add(MAP);
    }

    size_t _do_reorder(size_t *node, size_t count);

    void _swap(size_t n_, size_t m_);
    void _swap_props(size_t n_, size_t m_);
    void _swap_hierarchy(size_t n_, size_t m_);
    void _copy_hierarchy(size_t dst_, size_t src_);

    inline void _copy_props(size_t dst_, size_t src_)
    {
        _copy_props(dst_, this, src_);
    }

    inline void _copy_props_wo_key(size_t dst_, size_t src_)
    {
        _copy_props_wo_key(dst_, this, src_);
    }

    void _copy_props(size_t dst_, Tree const* that_tree, size_t src_)
    {
        auto      & C4_RESTRICT dst = *_p(dst_);
        auto const& C4_RESTRICT src = *that_tree->_p(src_);
        dst.m_type = src.m_type;
        dst.m_key  = src.m_key;
        dst.m_val  = src.m_val;
    }

    void _copy_props_wo_key(size_t dst_, Tree const* that_tree, size_t src_)
    {
        auto      & C4_RESTRICT dst = *_p(dst_);
        auto const& C4_RESTRICT src = *that_tree->_p(src_);
        dst.m_type = (src.m_type & ~_KEYMASK) | (dst.m_type & _KEYMASK);
        dst.m_val  = src.m_val;
    }

    inline void _clear_type(size_t node)
    {
        _p(node)->m_type = NOTYPE;
    }

    inline void _clear(size_t node)
    {
        auto *C4_RESTRICT n = _p(node);
        n->m_type = NOTYPE;
        n->m_key.clear();
        n->m_val.clear();
        n->m_parent = NONE;
        n->m_first_child = NONE;
        n->m_last_child = NONE;
    }

    inline void _clear_key(size_t node)
    {
        _p(node)->m_key.clear();
        _rem_flags(node, KEY);
    }

    inline void _clear_val(size_t node)
    {
        _p(node)->m_val.clear();
        _rem_flags(node, VAL);
    }

private:

    void _clear_range(size_t first, size_t num);

    size_t _claim();
    void   _claim_root();
    void   _release(size_t node);
    void   _free_list_add(size_t node);
    void   _free_list_rem(size_t node);

    void _set_hierarchy(size_t node, size_t parent, size_t after_sibling);
    void _rem_hierarchy(size_t node);

public:

    // members are exposed, but you should NOT access them directly

    NodeData * m_buf;
    size_t m_cap;

    size_t m_size;

    size_t m_free_head;
    size_t m_free_tail;

    substr m_arena;
    size_t m_arena_pos;

    Callbacks m_callbacks;

    TagDirective m_tag_directives[RYML_MAX_TAG_DIRECTIVES];

};

} // namespace yml
} // namespace c4


C4_SUPPRESS_WARNING_MSVC_POP
C4_SUPPRESS_WARNING_GCC_CLANG_POP


#endif /* _C4_YML_TREE_HPP_ */


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/tree.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/node.hpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/node.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_YML_NODE_HPP_
#define _C4_YML_NODE_HPP_

/** @file node.hpp
 * @see NodeRef */

//included above:
//#include <cstddef>

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/tree.hpp
//#include "c4/yml/tree.hpp"
#if !defined(C4_YML_TREE_HPP_) && !defined(_C4_YML_TREE_HPP_)
#error "amalgamate: file c4/yml/tree.hpp must have been included at this point"
#endif /* C4_YML_TREE_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/base64.hpp
//#include "c4/base64.hpp"
#if !defined(C4_BASE64_HPP_) && !defined(_C4_BASE64_HPP_)
#error "amalgamate: file c4/base64.hpp must have been included at this point"
#endif /* C4_BASE64_HPP_ */


#ifdef __GNUC__
#   pragma GCC diagnostic push
#   pragma GCC diagnostic ignored "-Wtype-limits"
#endif

#if defined(_MSC_VER)
#   pragma warning(push)
#   pragma warning(disable: 4251/*needs to have dll-interface to be used by clients of struct*/)
#   pragma warning(disable: 4296/*expression is always 'boolean_value'*/)
#endif

namespace c4 {
namespace yml {

template<class K> struct Key { K & k; };
template<> struct Key<fmt::const_base64_wrapper> { fmt::const_base64_wrapper wrapper; };
template<> struct Key<fmt::base64_wrapper> { fmt::base64_wrapper wrapper; };

template<class K> C4_ALWAYS_INLINE Key<K> key(K & k) { return Key<K>{k}; }
C4_ALWAYS_INLINE Key<fmt::const_base64_wrapper> key(fmt::const_base64_wrapper w) { return {w}; }
C4_ALWAYS_INLINE Key<fmt::base64_wrapper> key(fmt::base64_wrapper w) { return {w}; }

template<class T> void write(NodeRef *n, T const& v);

template<class T>
typename std::enable_if< ! std::is_floating_point<T>::value, bool>::type
read(NodeRef const& n, T *v);

template<class T>
typename std::enable_if<   std::is_floating_point<T>::value, bool>::type
read(NodeRef const& n, T *v);


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

// forward decls
class NodeRef;
class ConstNodeRef;

//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

namespace detail {

template<class NodeRefType>
struct child_iterator
{
    using value_type = NodeRefType;
    using tree_type = typename NodeRefType::tree_type;

    tree_type * C4_RESTRICT m_tree;
    size_t m_child_id;

    child_iterator(tree_type * t, size_t id) : m_tree(t), m_child_id(id) {}

    child_iterator& operator++ () { RYML_ASSERT(m_child_id != NONE); m_child_id = m_tree->next_sibling(m_child_id); return *this; }
    child_iterator& operator-- () { RYML_ASSERT(m_child_id != NONE); m_child_id = m_tree->prev_sibling(m_child_id); return *this; }

    NodeRefType operator*  () const { return NodeRefType(m_tree, m_child_id); }
    NodeRefType operator-> () const { return NodeRefType(m_tree, m_child_id); }

    bool operator!= (child_iterator that) const { RYML_ASSERT(m_tree == that.m_tree); return m_child_id != that.m_child_id; }
    bool operator== (child_iterator that) const { RYML_ASSERT(m_tree == that.m_tree); return m_child_id == that.m_child_id; }
};

template<class NodeRefType>
struct children_view_
{
    using n_iterator = child_iterator<NodeRefType>;

    n_iterator b, e;

    inline children_view_(n_iterator const& C4_RESTRICT b_,
                          n_iterator const& C4_RESTRICT e_) : b(b_), e(e_) {}

    inline n_iterator begin() const { return b; }
    inline n_iterator end  () const { return e; }
};

template<class NodeRefType, class Visitor>
bool _visit(NodeRefType &node, Visitor fn, size_t indentation_level, bool skip_root=false)
{
    size_t increment = 0;
    if( ! (node.is_root() && skip_root))
    {
        if(fn(node, indentation_level))
            return true;
        ++increment;
    }
    if(node.has_children())
    {
        for(auto ch : node.children())
        {
            if(_visit(ch, fn, indentation_level + increment, false)) // no need to forward skip_root as it won't be root
            {
                return true;
            }
        }
    }
    return false;
}

template<class NodeRefType, class Visitor>
bool _visit_stacked(NodeRefType &node, Visitor fn, size_t indentation_level, bool skip_root=false)
{
    size_t increment = 0;
    if( ! (node.is_root() && skip_root))
    {
        if(fn(node, indentation_level))
        {
            return true;
        }
        ++increment;
    }
    if(node.has_children())
    {
        fn.push(node, indentation_level);
        for(auto ch : node.children())
        {
            if(_visit_stacked(ch, fn, indentation_level + increment, false)) // no need to forward skip_root as it won't be root
            {
                fn.pop(node, indentation_level);
                return true;
            }
        }
        fn.pop(node, indentation_level);
    }
    return false;
}


//-----------------------------------------------------------------------------

/** a CRTP base for read-only node methods */
template<class Impl, class ConstImpl>
struct RoNodeMethods
{
    C4_SUPPRESS_WARNING_GCC_CLANG_WITH_PUSH("-Wcast-align")
    // helper CRTP macros, undefined at the end
    #define tree_ ((ConstImpl const* C4_RESTRICT)this)->m_tree
    #define id_ ((ConstImpl const* C4_RESTRICT)this)->m_id
    #define tree__ ((Impl const* C4_RESTRICT)this)->m_tree
    #define id__ ((Impl const* C4_RESTRICT)this)->m_id
    // require valid
    #define _C4RV()                                       \
        RYML_ASSERT(tree_ != nullptr);                    \
        _RYML_CB_ASSERT(tree_->m_callbacks, id_ != NONE)
    #define _C4_IF_MUTABLE(ty) typename std::enable_if<!std::is_same<U, ConstImpl>::value, ty>::type

public:

    /** @name node property getters */
    /** @{ */

    /** returns the data or null when the id is NONE */
    C4_ALWAYS_INLINE C4_PURE NodeData const* get() const noexcept { RYML_ASSERT(tree_ != nullptr); return tree_->get(id_); }
    /** returns the data or null when the id is NONE */
    template<class U=Impl>
    C4_ALWAYS_INLINE C4_PURE auto get() noexcept -> _C4_IF_MUTABLE(NodeData*) { RYML_ASSERT(tree_ != nullptr); return tree__->get(id__); }

    C4_ALWAYS_INLINE C4_PURE NodeType    type() const noexcept { _C4RV(); return tree_->type(id_); }
    C4_ALWAYS_INLINE C4_PURE const char* type_str() const noexcept { return tree_->type_str(id_); }

    C4_ALWAYS_INLINE C4_PURE csubstr key()        const noexcept { _C4RV(); return tree_->key(id_); }
    C4_ALWAYS_INLINE C4_PURE csubstr key_tag()    const noexcept { _C4RV(); return tree_->key_tag(id_); }
    C4_ALWAYS_INLINE C4_PURE csubstr key_ref()    const noexcept { _C4RV(); return tree_->key_ref(id_); }
    C4_ALWAYS_INLINE C4_PURE csubstr key_anchor() const noexcept { _C4RV(); return tree_->key_anchor(id_); }

    C4_ALWAYS_INLINE C4_PURE csubstr val()        const noexcept { _C4RV(); return tree_->val(id_); }
    C4_ALWAYS_INLINE C4_PURE csubstr val_tag()    const noexcept { _C4RV(); return tree_->val_tag(id_); }
    C4_ALWAYS_INLINE C4_PURE csubstr val_ref()    const noexcept { _C4RV(); return tree_->val_ref(id_); }
    C4_ALWAYS_INLINE C4_PURE csubstr val_anchor() const noexcept { _C4RV(); return tree_->val_anchor(id_); }

    C4_ALWAYS_INLINE C4_PURE NodeScalar const& keysc() const noexcept { _C4RV(); return tree_->keysc(id_); }
    C4_ALWAYS_INLINE C4_PURE NodeScalar const& valsc() const noexcept { _C4RV(); return tree_->valsc(id_); }

    C4_ALWAYS_INLINE C4_PURE bool key_is_null() const noexcept { _C4RV(); return tree_->key_is_null(id_); }
    C4_ALWAYS_INLINE C4_PURE bool val_is_null() const noexcept { _C4RV(); return tree_->val_is_null(id_); }

    /** @} */

public:

    /** @name node property predicates */
    /** @{ */

    C4_ALWAYS_INLINE C4_PURE bool empty()            const noexcept { _C4RV(); return tree_->empty(id_); }
    C4_ALWAYS_INLINE C4_PURE bool is_stream()        const noexcept { _C4RV(); return tree_->is_stream(id_); }
    C4_ALWAYS_INLINE C4_PURE bool is_doc()           const noexcept { _C4RV(); return tree_->is_doc(id_); }
    C4_ALWAYS_INLINE C4_PURE bool is_container()     const noexcept { _C4RV(); return tree_->is_container(id_); }
    C4_ALWAYS_INLINE C4_PURE bool is_map()           const noexcept { _C4RV(); return tree_->is_map(id_); }
    C4_ALWAYS_INLINE C4_PURE bool is_seq()           const noexcept { _C4RV(); return tree_->is_seq(id_); }
    C4_ALWAYS_INLINE C4_PURE bool has_val()          const noexcept { _C4RV(); return tree_->has_val(id_); }
    C4_ALWAYS_INLINE C4_PURE bool has_key()          const noexcept { _C4RV(); return tree_->has_key(id_); }
    C4_ALWAYS_INLINE C4_PURE bool is_val()           const noexcept { _C4RV(); return tree_->is_val(id_); }
    C4_ALWAYS_INLINE C4_PURE bool is_keyval()        const noexcept { _C4RV(); return tree_->is_keyval(id_); }
    C4_ALWAYS_INLINE C4_PURE bool has_key_tag()      const noexcept { _C4RV(); return tree_->has_key_tag(id_); }
    C4_ALWAYS_INLINE C4_PURE bool has_val_tag()      const noexcept { _C4RV(); return tree_->has_val_tag(id_); }
    C4_ALWAYS_INLINE C4_PURE bool has_key_anchor()   const noexcept { _C4RV(); return tree_->has_key_anchor(id_); }
    C4_ALWAYS_INLINE C4_PURE bool is_key_anchor()    const noexcept { _C4RV(); return tree_->is_key_anchor(id_); }
    C4_ALWAYS_INLINE C4_PURE bool has_val_anchor()   const noexcept { _C4RV(); return tree_->has_val_anchor(id_); }
    C4_ALWAYS_INLINE C4_PURE bool is_val_anchor()    const noexcept { _C4RV(); return tree_->is_val_anchor(id_); }
    C4_ALWAYS_INLINE C4_PURE bool has_anchor()       const noexcept { _C4RV(); return tree_->has_anchor(id_); }
    C4_ALWAYS_INLINE C4_PURE bool is_anchor()        const noexcept { _C4RV(); return tree_->is_anchor(id_); }
    C4_ALWAYS_INLINE C4_PURE bool is_key_ref()       const noexcept { _C4RV(); return tree_->is_key_ref(id_); }
    C4_ALWAYS_INLINE C4_PURE bool is_val_ref()       const noexcept { _C4RV(); return tree_->is_val_ref(id_); }
    C4_ALWAYS_INLINE C4_PURE bool is_ref()           const noexcept { _C4RV(); return tree_->is_ref(id_); }
    C4_ALWAYS_INLINE C4_PURE bool is_anchor_or_ref() const noexcept { _C4RV(); return tree_->is_anchor_or_ref(id_); }
    C4_ALWAYS_INLINE C4_PURE bool is_key_quoted()    const noexcept { _C4RV(); return tree_->is_key_quoted(id_); }
    C4_ALWAYS_INLINE C4_PURE bool is_val_quoted()    const noexcept { _C4RV(); return tree_->is_val_quoted(id_); }
    C4_ALWAYS_INLINE C4_PURE bool is_quoted()        const noexcept { _C4RV(); return tree_->is_quoted(id_); }
    C4_ALWAYS_INLINE C4_PURE bool parent_is_seq()    const noexcept { _C4RV(); return tree_->parent_is_seq(id_); }
    C4_ALWAYS_INLINE C4_PURE bool parent_is_map()    const noexcept { _C4RV(); return tree_->parent_is_map(id_); }

    /** @} */

public:

    /** @name hierarchy predicates */
    /** @{ */

    C4_ALWAYS_INLINE C4_PURE bool is_root()    const noexcept { _C4RV(); return tree_->is_root(id_); }
    C4_ALWAYS_INLINE C4_PURE bool has_parent() const noexcept { _C4RV(); return tree_->has_parent(id_); }

    C4_ALWAYS_INLINE C4_PURE bool has_child(ConstImpl const& ch) const noexcept { _C4RV(); return tree_->has_child(id_, ch.m_id); }
    C4_ALWAYS_INLINE C4_PURE bool has_child(csubstr name) const noexcept { _C4RV(); return tree_->has_child(id_, name); }
    C4_ALWAYS_INLINE C4_PURE bool has_children() const noexcept { _C4RV(); return tree_->has_children(id_); }

    C4_ALWAYS_INLINE C4_PURE bool has_sibling(ConstImpl const& n) const noexcept { _C4RV(); return tree_->has_sibling(id_, n.m_id); }
    C4_ALWAYS_INLINE C4_PURE bool has_sibling(csubstr name) const noexcept { _C4RV(); return tree_->has_sibling(id_, name); }
    /** counts with this */
    C4_ALWAYS_INLINE C4_PURE bool has_siblings() const noexcept { _C4RV(); return tree_->has_siblings(id_); }
    /** does not count with this */
    C4_ALWAYS_INLINE C4_PURE bool has_other_siblings() const noexcept { _C4RV(); return tree_->has_other_siblings(id_); }

    /** @} */

public:

    /** @name hierarchy getters */
    /** @{ */


    template<class U=Impl>
    C4_ALWAYS_INLINE C4_PURE auto doc(size_t num) noexcept -> _C4_IF_MUTABLE(Impl) { _C4RV(); return {tree__, tree__->doc(num)}; }
    C4_ALWAYS_INLINE C4_PURE ConstImpl doc(size_t num) const noexcept { _C4RV(); return {tree_, tree_->doc(num)}; }


    template<class U=Impl>
    C4_ALWAYS_INLINE C4_PURE auto parent() noexcept -> _C4_IF_MUTABLE(Impl) { _C4RV(); return {tree__, tree__->parent(id__)}; }
    C4_ALWAYS_INLINE C4_PURE ConstImpl parent() const noexcept { _C4RV(); return {tree_, tree_->parent(id_)}; }


    /** O(#num_children) */
    C4_ALWAYS_INLINE C4_PURE size_t child_pos(ConstImpl const& n) const noexcept { _C4RV(); return tree_->child_pos(id_, n.m_id); }
    C4_ALWAYS_INLINE C4_PURE size_t num_children() const noexcept { _C4RV(); return tree_->num_children(id_); }

    template<class U=Impl>
    C4_ALWAYS_INLINE C4_PURE auto first_child() noexcept -> _C4_IF_MUTABLE(Impl) { _C4RV(); return {tree__, tree__->first_child(id__)}; }
    C4_ALWAYS_INLINE C4_PURE ConstImpl first_child() const noexcept { _C4RV(); return {tree_, tree_->first_child(id_)}; }

    template<class U=Impl>
    C4_ALWAYS_INLINE C4_PURE auto last_child() noexcept -> _C4_IF_MUTABLE(Impl) { _C4RV(); return {tree__, tree__->last_child(id__)}; }
    C4_ALWAYS_INLINE C4_PURE ConstImpl last_child () const noexcept { _C4RV(); return {tree_, tree_->last_child (id_)}; }

    template<class U=Impl>
    C4_ALWAYS_INLINE C4_PURE auto child(size_t pos) noexcept -> _C4_IF_MUTABLE(Impl) { _C4RV(); return {tree__, tree__->child(id__, pos)}; }
    C4_ALWAYS_INLINE C4_PURE ConstImpl child(size_t pos) const noexcept { _C4RV(); return {tree_, tree_->child(id_, pos)}; }

    template<class U=Impl>
    C4_ALWAYS_INLINE C4_PURE auto find_child(csubstr name)  noexcept -> _C4_IF_MUTABLE(Impl) { _C4RV(); return {tree__, tree__->find_child(id__, name)}; }
    C4_ALWAYS_INLINE C4_PURE ConstImpl find_child(csubstr name) const noexcept { _C4RV(); return {tree_, tree_->find_child(id_, name)}; }


    /** O(#num_siblings) */
    C4_ALWAYS_INLINE C4_PURE size_t num_siblings() const noexcept { _C4RV(); return tree_->num_siblings(id_); }
    C4_ALWAYS_INLINE C4_PURE size_t num_other_siblings() const noexcept { _C4RV(); return tree_->num_other_siblings(id_); }
    C4_ALWAYS_INLINE C4_PURE size_t sibling_pos(ConstImpl const& n) const noexcept { _C4RV(); return tree_->child_pos(tree_->parent(id_), n.m_id); }

    template<class U=Impl>
    C4_ALWAYS_INLINE C4_PURE auto prev_sibling() noexcept -> _C4_IF_MUTABLE(Impl) { _C4RV(); return {tree__, tree__->prev_sibling(id__)}; }
    C4_ALWAYS_INLINE C4_PURE ConstImpl prev_sibling() const noexcept { _C4RV(); return {tree_, tree_->prev_sibling(id_)}; }

    template<class U=Impl>
    C4_ALWAYS_INLINE C4_PURE auto next_sibling() noexcept -> _C4_IF_MUTABLE(Impl) { _C4RV(); return {tree__, tree__->next_sibling(id__)}; }
    C4_ALWAYS_INLINE C4_PURE ConstImpl next_sibling() const noexcept { _C4RV(); return {tree_, tree_->next_sibling(id_)}; }

    template<class U=Impl>
    C4_ALWAYS_INLINE C4_PURE auto first_sibling() noexcept -> _C4_IF_MUTABLE(Impl) { _C4RV(); return {tree__, tree__->first_sibling(id__)}; }
    C4_ALWAYS_INLINE C4_PURE ConstImpl first_sibling() const noexcept { _C4RV(); return {tree_, tree_->first_sibling(id_)}; }

    template<class U=Impl>
    C4_ALWAYS_INLINE C4_PURE auto last_sibling() noexcept -> _C4_IF_MUTABLE(Impl) { _C4RV(); return {tree__, tree__->last_sibling(id__)}; }
    C4_ALWAYS_INLINE C4_PURE ConstImpl last_sibling () const noexcept { _C4RV(); return {tree_, tree_->last_sibling(id_)}; }

    template<class U=Impl>
    C4_ALWAYS_INLINE C4_PURE auto sibling(size_t pos) noexcept -> _C4_IF_MUTABLE(Impl) { _C4RV(); return {tree__, tree__->sibling(id__, pos)}; }
    C4_ALWAYS_INLINE C4_PURE ConstImpl sibling(size_t pos) const noexcept { _C4RV(); return {tree_, tree_->sibling(id_, pos)}; }

    template<class U=Impl>
    C4_ALWAYS_INLINE C4_PURE auto find_sibling(csubstr name) noexcept -> _C4_IF_MUTABLE(Impl) { _C4RV(); return {tree__, tree__->find_sibling(id__, name)}; }
    C4_ALWAYS_INLINE C4_PURE ConstImpl find_sibling(csubstr name) const noexcept { _C4RV(); return {tree_, tree_->find_sibling(id_, name)}; }


    /** O(num_children) */
    C4_ALWAYS_INLINE C4_PURE ConstImpl operator[] (csubstr k) const noexcept
    {
        _C4RV();
        size_t ch = tree_->find_child(id_, k);
        _RYML_CB_ASSERT(tree_->m_callbacks, ch != NONE);
        return {tree_, ch};
    }
    /** Find child by key. O(num_children). returns a seed node if no such child is found.  */
    template<class U=Impl>
    C4_ALWAYS_INLINE C4_PURE auto operator[] (csubstr k) noexcept -> _C4_IF_MUTABLE(Impl)
    {
        _C4RV();
        size_t ch = tree__->find_child(id__, k);
        return ch != NONE ? Impl(tree__, ch) : NodeRef(tree__, id__, k);
    }

    /** O(num_children) */
    C4_ALWAYS_INLINE C4_PURE ConstImpl operator[] (size_t pos) const noexcept
    {
        _C4RV();
        size_t ch = tree_->child(id_, pos);
        _RYML_CB_ASSERT(tree_->m_callbacks, ch != NONE);
        return {tree_, ch};
    }

    /** Find child by position. O(pos). returns a seed node if no such child is found.  */
    template<class U=Impl>
    C4_ALWAYS_INLINE C4_PURE auto operator[] (size_t pos) noexcept -> _C4_IF_MUTABLE(Impl)
    {
        _C4RV();
        size_t ch = tree__->child(id__, pos);
        return ch != NONE ? Impl(tree__, ch) : NodeRef(tree__, id__, pos);
    }

    /** @} */

public:

    /** deserialization */
    /** @{ */

    template<class T>
    ConstImpl const& operator>> (T &v) const
    {
        _C4RV();
        if( ! read((ConstImpl const&)*this, &v))
            _RYML_CB_ERR(tree_->m_callbacks, "could not deserialize value");
        return *((ConstImpl const*)this);
    }

    /** deserialize the node's key to the given variable */
    template<class T>
    ConstImpl const& operator>> (Key<T> v) const
    {
        _C4RV();
        if( ! from_chars(key(), &v.k))
            _RYML_CB_ERR(tree_->m_callbacks, "could not deserialize key");
        return *((ConstImpl const*)this);
    }

    /** deserialize the node's key as base64 */
    ConstImpl const& operator>> (Key<fmt::base64_wrapper> w) const
    {
        deserialize_key(w.wrapper);
        return *((ConstImpl const*)this);
    }

    /** deserialize the node's val as base64 */
    ConstImpl const& operator>> (fmt::base64_wrapper w) const
    {
        deserialize_val(w);
        return *((ConstImpl const*)this);
    }

    /** decode the base64-encoded key and assign the
     * decoded blob to the given buffer/
     * @return the size of base64-decoded blob */
    size_t deserialize_key(fmt::base64_wrapper v) const
    {
        _C4RV();
        return from_chars(key(), &v);
    }
    /** decode the base64-encoded key and assign the
     * decoded blob to the given buffer/
     * @return the size of base64-decoded blob */
    size_t deserialize_val(fmt::base64_wrapper v) const
    {
        _C4RV();
        return from_chars(val(), &v);
    };

    template<class T>
    bool get_if(csubstr name, T *var) const
    {
        auto ch = find_child(name);
        if(!ch.valid())
            return false;
        ch >> *var;
        return true;
    }

    template<class T>
    bool get_if(csubstr name, T *var, T const& fallback) const
    {
        auto ch = find_child(name);
        if(ch.valid())
        {
            ch >> *var;
            return true;
        }
        else
        {
            *var = fallback;
            return false;
        }
    }

    /** @} */

public:

    #if defined(__clang__)
    #   pragma clang diagnostic push
    #   pragma clang diagnostic ignored "-Wnull-dereference"
    #elif defined(__GNUC__)
    #   pragma GCC diagnostic push
    #   if __GNUC__ >= 6
    #       pragma GCC diagnostic ignored "-Wnull-dereference"
    #   endif
    #endif

    /** @name iteration */
    /** @{ */

    using iterator = detail::child_iterator<Impl>;
    using const_iterator = detail::child_iterator<ConstImpl>;
    using children_view = detail::children_view_<Impl>;
    using const_children_view = detail::children_view_<ConstImpl>;

    template<class U=Impl>
    C4_ALWAYS_INLINE C4_PURE auto begin() noexcept -> _C4_IF_MUTABLE(iterator) { _C4RV(); return iterator(tree__, tree__->first_child(id__)); }
    C4_ALWAYS_INLINE C4_PURE const_iterator begin() const noexcept { _C4RV(); return const_iterator(tree_, tree_->first_child(id_)); }
    C4_ALWAYS_INLINE C4_PURE const_iterator cbegin() const noexcept { _C4RV(); return const_iterator(tree_, tree_->first_child(id_)); }

    template<class U=Impl>
    C4_ALWAYS_INLINE C4_PURE auto end() noexcept -> _C4_IF_MUTABLE(iterator) { _C4RV(); return iterator(tree__, NONE); }
    C4_ALWAYS_INLINE C4_PURE const_iterator end() const noexcept { _C4RV(); return const_iterator(tree_, NONE); }
    C4_ALWAYS_INLINE C4_PURE const_iterator cend() const noexcept { _C4RV(); return const_iterator(tree_, tree_->first_child(id_)); }

    /** get an iterable view over children */
    template<class U=Impl>
    C4_ALWAYS_INLINE C4_PURE auto children() noexcept -> _C4_IF_MUTABLE(children_view) { _C4RV(); return children_view(begin(), end()); }
    /** get an iterable view over children */
    C4_ALWAYS_INLINE C4_PURE const_children_view children() const noexcept { _C4RV(); return const_children_view(begin(), end()); }
    /** get an iterable view over children */
    C4_ALWAYS_INLINE C4_PURE const_children_view cchildren() const noexcept { _C4RV(); return const_children_view(begin(), end()); }

    /** get an iterable view over all siblings (including the calling node) */
    template<class U=Impl>
    C4_ALWAYS_INLINE C4_PURE auto siblings() noexcept -> _C4_IF_MUTABLE(children_view)
    {
        _C4RV();
        NodeData const *nd = tree__->get(id__);
        return (nd->m_parent != NONE) ? // does it have a parent?
            children_view(iterator(tree__, tree_->get(nd->m_parent)->m_first_child), iterator(tree__, NONE))
            :
            children_view(end(), end());
    }
    /** get an iterable view over all siblings (including the calling node) */
    C4_ALWAYS_INLINE C4_PURE const_children_view siblings() const noexcept
    {
        _C4RV();
        NodeData const *nd = tree_->get(id_);
        return (nd->m_parent != NONE) ? // does it have a parent?
            const_children_view(const_iterator(tree_, tree_->get(nd->m_parent)->m_first_child), const_iterator(tree_, NONE))
            :
            const_children_view(end(), end());
    }
    /** get an iterable view over all siblings (including the calling node) */
    C4_ALWAYS_INLINE C4_PURE const_children_view csiblings() const noexcept { return siblings(); }

    /** visit every child node calling fn(node) */
    template<class Visitor>
    C4_ALWAYS_INLINE C4_PURE bool visit(Visitor fn, size_t indentation_level=0, bool skip_root=true) const noexcept
    {
        return detail::_visit(*(ConstImpl*)this, fn, indentation_level, skip_root);
    }
    /** visit every child node calling fn(node) */
    template<class Visitor, class U=Impl>
    auto visit(Visitor fn, size_t indentation_level=0, bool skip_root=true) noexcept
        -> _C4_IF_MUTABLE(bool)
    {
        return detail::_visit(*(Impl*)this, fn, indentation_level, skip_root);
    }

    /** visit every child node calling fn(node, level) */
    template<class Visitor>
    C4_ALWAYS_INLINE C4_PURE bool visit_stacked(Visitor fn, size_t indentation_level=0, bool skip_root=true) const noexcept
    {
        return detail::_visit_stacked(*(ConstImpl*)this, fn, indentation_level, skip_root);
    }
    /** visit every child node calling fn(node, level) */
    template<class Visitor, class U=Impl>
    auto visit_stacked(Visitor fn, size_t indentation_level=0, bool skip_root=true) noexcept
        -> _C4_IF_MUTABLE(bool)
    {
        return detail::_visit_stacked(*(Impl*)this, fn, indentation_level, skip_root);
    }

    /** @} */

    #if defined(__clang__)
    #   pragma clang diagnostic pop
    #elif defined(__GNUC__)
    #   pragma GCC diagnostic pop
    #endif

    #undef _C4_IF_MUTABLE
    #undef _C4RV
    #undef tree_
    #undef tree__
    #undef id_
    #undef id__

    C4_SUPPRESS_WARNING_GCC_CLANG_POP
};

} // namespace detail


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
class RYML_EXPORT ConstNodeRef : public detail::RoNodeMethods<ConstNodeRef, ConstNodeRef>
{
public:

    using tree_type = Tree const;

public:

    Tree const* C4_RESTRICT m_tree;
    size_t m_id;

    friend NodeRef;
    friend struct detail::RoNodeMethods<ConstNodeRef, ConstNodeRef>;

public:

    /** @name construction */
    /** @{ */

    ConstNodeRef() : m_tree(nullptr), m_id(NONE) {}
    ConstNodeRef(Tree const &t) : m_tree(&t), m_id(t .root_id()) {}
    ConstNodeRef(Tree const *t) : m_tree(t ), m_id(t->root_id()) {}
    ConstNodeRef(Tree const *t, size_t id) : m_tree(t), m_id(id) {}
    ConstNodeRef(std::nullptr_t) : m_tree(nullptr), m_id(NONE) {}

    ConstNodeRef(ConstNodeRef const&) = default;
    ConstNodeRef(ConstNodeRef     &&) = default;

    ConstNodeRef(NodeRef const&);
    ConstNodeRef(NodeRef     &&);

    /** @} */

public:

    /** @name assignment */
    /** @{ */

    ConstNodeRef& operator= (std::nullptr_t) { m_tree = nullptr; m_id = NONE; return *this; }

    ConstNodeRef& operator= (ConstNodeRef const&) = default;
    ConstNodeRef& operator= (ConstNodeRef     &&) = default;

    ConstNodeRef& operator= (NodeRef const&);
    ConstNodeRef& operator= (NodeRef     &&);


    /** @} */

public:

    /** @name state queries */
    /** @{ */

    C4_ALWAYS_INLINE C4_PURE bool valid() const noexcept { return m_tree != nullptr && m_id != NONE; }

    /** @} */

public:

    /** @name member getters */
    /** @{ */

    C4_ALWAYS_INLINE C4_PURE Tree const* tree() const noexcept { return m_tree; }
    C4_ALWAYS_INLINE C4_PURE size_t id() const noexcept { return m_id; }

    /** @} */

public:

    /** @name comparisons */
    /** @{ */

    C4_ALWAYS_INLINE C4_PURE bool operator== (ConstNodeRef const& that) const noexcept { RYML_ASSERT(that.m_tree == m_tree); return m_id == that.m_id; }
    C4_ALWAYS_INLINE C4_PURE bool operator!= (ConstNodeRef const& that) const noexcept { RYML_ASSERT(that.m_tree == m_tree); return ! this->operator==(that); }

    C4_ALWAYS_INLINE C4_PURE bool operator== (std::nullptr_t) const noexcept { return m_tree == nullptr || m_id == NONE; }
    C4_ALWAYS_INLINE C4_PURE bool operator!= (std::nullptr_t) const noexcept { return ! this->operator== (nullptr); }

    C4_ALWAYS_INLINE C4_PURE bool operator== (csubstr val) const noexcept { RYML_ASSERT(has_val()); return m_tree->val(m_id) == val; }
    C4_ALWAYS_INLINE C4_PURE bool operator!= (csubstr val) const noexcept { RYML_ASSERT(has_val()); return m_tree->val(m_id) != val; }

    /** @} */

};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** a reference to a node in an existing yaml tree, offering a more
 * convenient API than the index-based API used in the tree. */
class RYML_EXPORT NodeRef : public detail::RoNodeMethods<NodeRef, ConstNodeRef>
{
public:

    using tree_type = Tree;
    using base_type = detail::RoNodeMethods<NodeRef, ConstNodeRef>;

private:

    Tree *C4_RESTRICT m_tree;
    size_t m_id;

    /** This member is used to enable lazy operator[] writing. When a child
     * with a key or index is not found, m_id is set to the id of the parent
     * and the asked-for key or index are stored in this member until a write
     * does happen. Then it is given as key or index for creating the child.
     * When a key is used, the csubstr stores it (so the csubstr's string is
     * non-null and the csubstr's size is different from NONE). When an index is
     * used instead, the csubstr's string is set to null, and only the csubstr's
     * size is set to a value different from NONE. Otherwise, when operator[]
     * does find the child then this member is empty: the string is null and
     * the size is NONE. */
    csubstr m_seed;

    friend ConstNodeRef;
    friend struct detail::RoNodeMethods<NodeRef, ConstNodeRef>;

    // require valid: a helper macro, undefined at the end
    #define _C4RV()                                                         \
        RYML_ASSERT(m_tree != nullptr);                                     \
        _RYML_CB_ASSERT(m_tree->m_callbacks, m_id != NONE && !is_seed())

public:

    /** @name construction */
    /** @{ */

    NodeRef() : m_tree(nullptr), m_id(NONE), m_seed() { _clear_seed(); }
    NodeRef(Tree &t) : m_tree(&t), m_id(t .root_id()), m_seed() { _clear_seed(); }
    NodeRef(Tree *t) : m_tree(t ), m_id(t->root_id()), m_seed() { _clear_seed(); }
    NodeRef(Tree *t, size_t id) : m_tree(t), m_id(id), m_seed() { _clear_seed(); }
    NodeRef(Tree *t, size_t id, size_t seed_pos) : m_tree(t), m_id(id), m_seed() { m_seed.str = nullptr; m_seed.len = seed_pos; }
    NodeRef(Tree *t, size_t id, csubstr  seed_key) : m_tree(t), m_id(id), m_seed(seed_key) {}
    NodeRef(std::nullptr_t) : m_tree(nullptr), m_id(NONE), m_seed() {}

    /** @} */

public:

    /** @name assignment */
    /** @{ */

    NodeRef(NodeRef const&) = default;
    NodeRef(NodeRef     &&) = default;

    NodeRef& operator= (NodeRef const&) = default;
    NodeRef& operator= (NodeRef     &&) = default;

    /** @} */

public:

    /** @name state queries */
    /** @{ */

    inline bool valid() const { return m_tree != nullptr && m_id != NONE; }
    inline bool is_seed() const { return m_seed.str != nullptr || m_seed.len != NONE; }

    inline void _clear_seed() { /*do this manually or an assert is triggered*/ m_seed.str = nullptr; m_seed.len = NONE; }

    /** @} */

public:

    /** @name comparisons */
    /** @{ */

    inline bool operator== (NodeRef const& that) const { _C4RV(); RYML_ASSERT(that.valid() && !that.is_seed()); RYML_ASSERT(that.m_tree == m_tree); return m_id == that.m_id; }
    inline bool operator!= (NodeRef const& that) const { return ! this->operator==(that); }

    inline bool operator== (ConstNodeRef const& that) const { _C4RV(); RYML_ASSERT(that.valid()); RYML_ASSERT(that.m_tree == m_tree); return m_id == that.m_id; }
    inline bool operator!= (ConstNodeRef const& that) const { return ! this->operator==(that); }

    inline bool operator== (std::nullptr_t) const { return m_tree == nullptr || m_id == NONE || is_seed(); }
    inline bool operator!= (std::nullptr_t) const { return m_tree != nullptr && m_id != NONE && !is_seed(); }

    inline bool operator== (csubstr val) const { _C4RV(); RYML_ASSERT(has_val()); return m_tree->val(m_id) == val; }
    inline bool operator!= (csubstr val) const { _C4RV(); RYML_ASSERT(has_val()); return m_tree->val(m_id) != val; }

    //inline operator bool () const { return m_tree == nullptr || m_id == NONE || is_seed(); }

    /** @} */

public:

    /** @name node property getters */
    /** @{ */

    C4_ALWAYS_INLINE C4_PURE Tree * tree() noexcept { return m_tree; }
    C4_ALWAYS_INLINE C4_PURE Tree const* tree() const noexcept { return m_tree; }

    C4_ALWAYS_INLINE C4_PURE size_t id() const noexcept { return m_id; }

    /** @} */

public:

    /** @name node modifiers */
    /** @{ */

    void change_type(NodeType t) { _C4RV(); m_tree->change_type(m_id, t); }

    void set_type(NodeType t) { _C4RV(); m_tree->_set_flags(m_id, t); }
    void set_key(csubstr key) { _C4RV(); m_tree->_set_key(m_id, key); }
    void set_val(csubstr val) { _C4RV(); m_tree->_set_val(m_id, val); }
    void set_key_tag(csubstr key_tag) { _C4RV(); m_tree->set_key_tag(m_id, key_tag); }
    void set_val_tag(csubstr val_tag) { _C4RV(); m_tree->set_val_tag(m_id, val_tag); }
    void set_key_anchor(csubstr key_anchor) { _C4RV(); m_tree->set_key_anchor(m_id, key_anchor); }
    void set_val_anchor(csubstr val_anchor) { _C4RV(); m_tree->set_val_anchor(m_id, val_anchor); }
    void set_key_ref(csubstr key_ref) { _C4RV(); m_tree->set_key_ref(m_id, key_ref); }
    void set_val_ref(csubstr val_ref) { _C4RV(); m_tree->set_val_ref(m_id, val_ref); }

    template<class T>
    size_t set_key_serialized(T const& C4_RESTRICT k)
    {
        _C4RV();
        csubstr s = m_tree->to_arena(k);
        m_tree->_set_key(m_id, s);
        return s.len;
    }
    template<class T>
    size_t set_val_serialized(T const& C4_RESTRICT v)
    {
        _C4RV();
        csubstr s = m_tree->to_arena(v);
        m_tree->_set_val(m_id, s);
        return s.len;
    }
    size_t set_val_serialized(std::nullptr_t)
    {
        _C4RV();
        m_tree->_set_val(m_id, csubstr{});
        return 0;
    }

    /** encode a blob as base64, then assign the result to the node's key
     * @return the size of base64-encoded blob */
    size_t set_key_serialized(fmt::const_base64_wrapper w);
    /** encode a blob as base64, then assign the result to the node's val
     * @return the size of base64-encoded blob */
    size_t set_val_serialized(fmt::const_base64_wrapper w);

public:

    inline void clear()
    {
        if(is_seed())
            return;
        m_tree->remove_children(m_id);
        m_tree->_clear(m_id);
    }

    inline void clear_key()
    {
        if(is_seed())
            return;
        m_tree->_clear_key(m_id);
    }

    inline void clear_val()
    {
        if(is_seed())
            return;
        m_tree->_clear_val(m_id);
    }

    inline void clear_children()
    {
        if(is_seed())
            return;
        m_tree->remove_children(m_id);
    }

    void create() { _apply_seed(); }

    inline void operator= (NodeType_e t)
    {
        _apply_seed();
        m_tree->_add_flags(m_id, t);
    }

    inline void operator|= (NodeType_e t)
    {
        _apply_seed();
        m_tree->_add_flags(m_id, t);
    }

    inline void operator= (NodeInit const& v)
    {
        _apply_seed();
        _apply(v);
    }

    inline void operator= (NodeScalar const& v)
    {
        _apply_seed();
        _apply(v);
    }

    inline void operator= (std::nullptr_t)
    {
        _apply_seed();
        _apply(csubstr{});
    }

    inline void operator= (csubstr v)
    {
        _apply_seed();
        _apply(v);
    }

    template<size_t N>
    inline void operator= (const char (&v)[N])
    {
        _apply_seed();
        csubstr sv;
        sv.assign<N>(v);
        _apply(sv);
    }

    /** @} */

public:

    /** @name serialization */
    /** @{ */

    /** serialize a variable to the arena */
    template<class T>
    inline csubstr to_arena(T const& C4_RESTRICT s)
    {
        _C4RV();
        return m_tree->to_arena(s);
    }

    /** serialize a variable, then assign the result to the node's val */
    inline NodeRef& operator<< (csubstr s)
    {
        // this overload is needed to prevent ambiguity (there's also
        // operator<< for writing a substr to a stream)
        _apply_seed();
        write(this, s);
        RYML_ASSERT(val() == s);
        return *this;
    }

    template<class T>
    inline NodeRef& operator<< (T const& C4_RESTRICT v)
    {
        _apply_seed();
        write(this, v);
        return *this;
    }

    /** serialize a variable, then assign the result to the node's key */
    template<class T>
    inline NodeRef& operator<< (Key<const T> const& C4_RESTRICT v)
    {
        _apply_seed();
        set_key_serialized(v.k);
        return *this;
    }

    /** serialize a variable, then assign the result to the node's key */
    template<class T>
    inline NodeRef& operator<< (Key<T> const& C4_RESTRICT v)
    {
        _apply_seed();
        set_key_serialized(v.k);
        return *this;
    }

    NodeRef& operator<< (Key<fmt::const_base64_wrapper> w)
    {
        set_key_serialized(w.wrapper);
        return *this;
    }

    NodeRef& operator<< (fmt::const_base64_wrapper w)
    {
        set_val_serialized(w);
        return *this;
    }

    /** @} */

private:

    void _apply_seed()
    {
        if(m_seed.str) // we have a seed key: use it to create the new child
        {
            //RYML_ASSERT(i.key.scalar.empty() || m_key == i.key.scalar || m_key.empty());
            m_id = m_tree->append_child(m_id);
            m_tree->_set_key(m_id, m_seed);
            m_seed.str = nullptr;
            m_seed.len = NONE;
        }
        else if(m_seed.len != NONE) // we have a seed index: create a child at that position
        {
            RYML_ASSERT(m_tree->num_children(m_id) == m_seed.len);
            m_id = m_tree->append_child(m_id);
            m_seed.str = nullptr;
            m_seed.len = NONE;
        }
        else
        {
            RYML_ASSERT(valid());
        }
    }

    inline void _apply(csubstr v)
    {
        m_tree->_set_val(m_id, v);
    }

    inline void _apply(NodeScalar const& v)
    {
        m_tree->_set_val(m_id, v);
    }

    inline void _apply(NodeInit const& i)
    {
        m_tree->_set(m_id, i);
    }

public:

    /** @name modification of hierarchy */
    /** @{ */

    inline NodeRef insert_child(NodeRef after)
    {
        _C4RV();
        RYML_ASSERT(after.m_tree == m_tree);
        NodeRef r(m_tree, m_tree->insert_child(m_id, after.m_id));
        return r;
    }

    inline NodeRef insert_child(NodeInit const& i, NodeRef after)
    {
        _C4RV();
        RYML_ASSERT(after.m_tree == m_tree);
        NodeRef r(m_tree, m_tree->insert_child(m_id, after.m_id));
        r._apply(i);
        return r;
    }

    inline NodeRef prepend_child()
    {
        _C4RV();
        NodeRef r(m_tree, m_tree->insert_child(m_id, NONE));
        return r;
    }

    inline NodeRef prepend_child(NodeInit const& i)
    {
        _C4RV();
        NodeRef r(m_tree, m_tree->insert_child(m_id, NONE));
        r._apply(i);
        return r;
    }

    inline NodeRef append_child()
    {
        _C4RV();
        NodeRef r(m_tree, m_tree->append_child(m_id));
        return r;
    }

    inline NodeRef append_child(NodeInit const& i)
    {
        _C4RV();
        NodeRef r(m_tree, m_tree->append_child(m_id));
        r._apply(i);
        return r;
    }

public:

    inline NodeRef insert_sibling(ConstNodeRef const& after)
    {
        _C4RV();
        RYML_ASSERT(after.m_tree == m_tree);
        NodeRef r(m_tree, m_tree->insert_sibling(m_id, after.m_id));
        return r;
    }

    inline NodeRef insert_sibling(NodeInit const& i, ConstNodeRef const& after)
    {
        _C4RV();
        RYML_ASSERT(after.m_tree == m_tree);
        NodeRef r(m_tree, m_tree->insert_sibling(m_id, after.m_id));
        r._apply(i);
        return r;
    }

    inline NodeRef prepend_sibling()
    {
        _C4RV();
        NodeRef r(m_tree, m_tree->prepend_sibling(m_id));
        return r;
    }

    inline NodeRef prepend_sibling(NodeInit const& i)
    {
        _C4RV();
        NodeRef r(m_tree, m_tree->prepend_sibling(m_id));
        r._apply(i);
        return r;
    }

    inline NodeRef append_sibling()
    {
        _C4RV();
        NodeRef r(m_tree, m_tree->append_sibling(m_id));
        return r;
    }

    inline NodeRef append_sibling(NodeInit const& i)
    {
        _C4RV();
        NodeRef r(m_tree, m_tree->append_sibling(m_id));
        r._apply(i);
        return r;
    }

public:

    inline void remove_child(NodeRef & child)
    {
        _C4RV();
        RYML_ASSERT(has_child(child));
        RYML_ASSERT(child.parent().id() == id());
        m_tree->remove(child.id());
        child.clear();
    }

    //! remove the nth child of this node
    inline void remove_child(size_t pos)
    {
        _C4RV();
        RYML_ASSERT(pos >= 0 && pos < num_children());
        size_t child = m_tree->child(m_id, pos);
        RYML_ASSERT(child != NONE);
        m_tree->remove(child);
    }

    //! remove a child by name
    inline void remove_child(csubstr key)
    {
        _C4RV();
        size_t child = m_tree->find_child(m_id, key);
        RYML_ASSERT(child != NONE);
        m_tree->remove(child);
    }

public:

    /** change the node's position within its parent, placing it after
     * @p after. To move to the first position in the parent, simply
     * pass an empty or default-constructed reference like this:
     * `n.move({})`. */
    inline void move(ConstNodeRef const& after)
    {
        _C4RV();
        m_tree->move(m_id, after.m_id);
    }

    /** move the node to a different @p parent (which may belong to a
     * different tree), placing it after @p after. When the
     * destination parent is in a new tree, then this node's tree
     * pointer is reset to the tree of the parent node. */
    inline void move(NodeRef const& parent, ConstNodeRef const& after)
    {
        _C4RV();
        if(parent.m_tree == m_tree)
        {
            m_tree->move(m_id, parent.m_id, after.m_id);
        }
        else
        {
            parent.m_tree->move(m_tree, m_id, parent.m_id, after.m_id);
            m_tree = parent.m_tree;
        }
    }

    /** duplicate the current node somewhere within its parent, and
     * place it after the node @p after. To place into the first
     * position of the parent, simply pass an empty or
     * default-constructed reference like this: `n.move({})`. */
    inline NodeRef duplicate(ConstNodeRef const& after) const
    {
        _C4RV();
        RYML_ASSERT(m_tree == after.m_tree || after.m_id == NONE);
        size_t dup = m_tree->duplicate(m_id, m_tree->parent(m_id), after.m_id);
        NodeRef r(m_tree, dup);
        return r;
    }

    /** duplicate the current node somewhere into a different @p parent
     * (possibly from a different tree), and place it after the node
     * @p after. To place into the first position of the parent,
     * simply pass an empty or default-constructed reference like
     * this: `n.move({})`. */
    inline NodeRef duplicate(NodeRef const& parent, ConstNodeRef const& after) const
    {
        _C4RV();
        RYML_ASSERT(parent.m_tree == after.m_tree || after.m_id == NONE);
        if(parent.m_tree == m_tree)
        {
            size_t dup = m_tree->duplicate(m_id, parent.m_id, after.m_id);
            NodeRef r(m_tree, dup);
            return r;
        }
        else
        {
            size_t dup = parent.m_tree->duplicate(m_tree, m_id, parent.m_id, after.m_id);
            NodeRef r(parent.m_tree, dup);
            return r;
        }
    }

    inline void duplicate_children(NodeRef const& parent, ConstNodeRef const& after) const
    {
        _C4RV();
        RYML_ASSERT(parent.m_tree == after.m_tree);
        if(parent.m_tree == m_tree)
        {
            m_tree->duplicate_children(m_id, parent.m_id, after.m_id);
        }
        else
        {
            parent.m_tree->duplicate_children(m_tree, m_id, parent.m_id, after.m_id);
        }
    }

    /** @} */

#undef _C4RV
};


//-----------------------------------------------------------------------------

inline ConstNodeRef::ConstNodeRef(NodeRef const& that)
    : m_tree(that.m_tree)
    , m_id(!that.is_seed() ? that.id() : NONE)
{
}

inline ConstNodeRef::ConstNodeRef(NodeRef && that)
    : m_tree(that.m_tree)
    , m_id(!that.is_seed() ? that.id() : NONE)
{
}


inline ConstNodeRef& ConstNodeRef::operator= (NodeRef const& that)
{
    m_tree = (that.m_tree);
    m_id = (!that.is_seed() ? that.id() : NONE);
    return *this;
}

inline ConstNodeRef& ConstNodeRef::operator= (NodeRef && that)
{
    m_tree = (that.m_tree);
    m_id = (!that.is_seed() ? that.id() : NONE);
    return *this;
}


//-----------------------------------------------------------------------------

template<class T>
inline void write(NodeRef *n, T const& v)
{
    n->set_val_serialized(v);
}

template<class T>
typename std::enable_if< ! std::is_floating_point<T>::value, bool>::type
inline read(NodeRef const& n, T *v)
{
    return from_chars(n.val(), v);
}
template<class T>
typename std::enable_if< ! std::is_floating_point<T>::value, bool>::type
inline read(ConstNodeRef const& n, T *v)
{
    return from_chars(n.val(), v);
}

template<class T>
typename std::enable_if<std::is_floating_point<T>::value, bool>::type
inline read(NodeRef const& n, T *v)
{
    return from_chars_float(n.val(), v);
}
template<class T>
typename std::enable_if<std::is_floating_point<T>::value, bool>::type
inline read(ConstNodeRef const& n, T *v)
{
    return from_chars_float(n.val(), v);
}


} // namespace yml
} // namespace c4


#if defined(_MSC_VER)
#   pragma warning(pop)
#endif

#ifdef __GNUC__
#   pragma GCC diagnostic pop
#endif

#endif /* _C4_YML_NODE_HPP_ */


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/node.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/writer.hpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/writer.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_YML_WRITER_HPP_
#define _C4_YML_WRITER_HPP_

#ifndef _C4_YML_COMMON_HPP_
#include "./common.hpp"
#endif

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/substr.hpp
//#include <c4/substr.hpp>
#if !defined(C4_SUBSTR_HPP_) && !defined(_C4_SUBSTR_HPP_)
#error "amalgamate: file c4/substr.hpp must have been included at this point"
#endif /* C4_SUBSTR_HPP_ */

//included above:
//#include <stdio.h>  // fwrite(), fputc()
//included above:
//#include <string.h> // memcpy()


namespace c4 {
namespace yml {


/** Repeat-Character: a character to be written a number of times. */
struct RepC
{
    char c;
    size_t num_times;
};
inline RepC indent_to(size_t num_levels)
{
    return {' ', size_t(2) * num_levels};
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
/** A writer that outputs to a file. Defaults to stdout. */
struct WriterFile
{
    FILE * m_file;
    size_t m_pos;

    WriterFile(FILE *f = nullptr) : m_file(f ? f : stdout), m_pos(0) {}

    inline substr _get(bool /*error_on_excess*/)
    {
        substr sp;
        sp.str = nullptr;
        sp.len = m_pos;
        return sp;
    }

    template<size_t N>
    inline void _do_write(const char (&a)[N])
    {
        fwrite(a, sizeof(char), N - 1, m_file);
        m_pos += N - 1;
    }

    inline void _do_write(csubstr sp)
    {
        #if defined(__clang__)
        #   pragma clang diagnostic push
        #   pragma GCC diagnostic ignored "-Wsign-conversion"
        #elif defined(__GNUC__)
        #   pragma GCC diagnostic push
        #   pragma GCC diagnostic ignored "-Wsign-conversion"
        #endif
        if(sp.empty()) return;
        fwrite(sp.str, sizeof(csubstr::char_type), sp.len, m_file);
        m_pos += sp.len;
        #if defined(__clang__)
        #   pragma clang diagnostic pop
        #elif defined(__GNUC__)
        #   pragma GCC diagnostic pop
        #endif
    }

    inline void _do_write(const char c)
    {
        fputc(c, m_file);
        ++m_pos;
    }

    inline void _do_write(RepC const rc)
    {
        for(size_t i = 0; i < rc.num_times; ++i)
        {
            fputc(rc.c, m_file);
        }
        m_pos += rc.num_times;
    }
};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
/** A writer that outputs to an STL-like ostream. */
template<class OStream>
struct WriterOStream
{
    OStream& m_stream;
    size_t   m_pos;

    WriterOStream(OStream &s) : m_stream(s), m_pos(0) {}

    inline substr _get(bool /*error_on_excess*/)
    {
        substr sp;
        sp.str = nullptr;
        sp.len = m_pos;
        return sp;
    }

    template<size_t N>
    inline void _do_write(const char (&a)[N])
    {
        m_stream.write(a, N - 1);
        m_pos += N - 1;
    }

    inline void _do_write(csubstr sp)
    {
        #if defined(__clang__)
        #   pragma clang diagnostic push
        #   pragma GCC diagnostic ignored "-Wsign-conversion"
        #elif defined(__GNUC__)
        #   pragma GCC diagnostic push
        #   pragma GCC diagnostic ignored "-Wsign-conversion"
        #endif
        if(sp.empty()) return;
        m_stream.write(sp.str, sp.len);
        m_pos += sp.len;
        #if defined(__clang__)
        #   pragma clang diagnostic pop
        #elif defined(__GNUC__)
        #   pragma GCC diagnostic pop
        #endif
    }

    inline void _do_write(const char c)
    {
        m_stream.put(c);
        ++m_pos;
    }

    inline void _do_write(RepC const rc)
    {
        for(size_t i = 0; i < rc.num_times; ++i)
        {
            m_stream.put(rc.c);
        }
        m_pos += rc.num_times;
    }
};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
/** a writer to a substr */
struct WriterBuf
{
    substr m_buf;
    size_t m_pos;

    WriterBuf(substr sp) : m_buf(sp), m_pos(0) {}

    inline substr _get(bool error_on_excess)
    {
        if(m_pos <= m_buf.len)
        {
            return m_buf.first(m_pos);
        }
        if(error_on_excess)
        {
            c4::yml::error("not enough space in the given buffer");
        }
        substr sp;
        sp.str = nullptr;
        sp.len = m_pos;
        return sp;
    }

    template<size_t N>
    inline void _do_write(const char (&a)[N])
    {
        RYML_ASSERT( ! m_buf.overlaps(a));
        if(m_pos + N-1 <= m_buf.len)
        {
            memcpy(&(m_buf[m_pos]), a, N-1);
        }
        m_pos += N-1;
    }

    inline void _do_write(csubstr sp)
    {
        if(sp.empty()) return;
        RYML_ASSERT( ! sp.overlaps(m_buf));
        if(m_pos + sp.len <= m_buf.len)
        {
            memcpy(&(m_buf[m_pos]), sp.str, sp.len);
        }
        m_pos += sp.len;
    }

    inline void _do_write(const char c)
    {
        if(m_pos + 1 <= m_buf.len)
        {
            m_buf[m_pos] = c;
        }
        ++m_pos;
    }

    inline void _do_write(RepC const rc)
    {
        if(m_pos + rc.num_times <= m_buf.len)
        {
            for(size_t i = 0; i < rc.num_times; ++i)
            {
                m_buf[m_pos + i] = rc.c;
            }
        }
        m_pos += rc.num_times;
    }
};


} // namespace yml
} // namespace c4

#endif /* _C4_YML_WRITER_HPP_ */


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/writer.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/detail/parser_dbg.hpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/detail/parser_dbg.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_YML_DETAIL_PARSER_DBG_HPP_
#define _C4_YML_DETAIL_PARSER_DBG_HPP_

#ifndef _C4_YML_COMMON_HPP_
#include "../common.hpp"
#endif
//included above:
//#include <cstdio>

//-----------------------------------------------------------------------------
// some debugging scaffolds

#if defined(_MSC_VER)
#   pragma warning(push)
#   pragma warning(disable: 4068/*unknown pragma*/)
#endif

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunknown-pragmas"
//#pragma GCC diagnostic ignored "-Wpragma-system-header-outside-header"
#pragma GCC system_header

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Werror"
#pragma clang diagnostic ignored "-Wgnu-zero-variadic-macro-arguments"

// some debugging scaffolds
#ifdef RYML_DBG
// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/dump.hpp
//#include <c4/dump.hpp>
#if !defined(C4_DUMP_HPP_) && !defined(_C4_DUMP_HPP_)
#error "amalgamate: file c4/dump.hpp must have been included at this point"
#endif /* C4_DUMP_HPP_ */

namespace c4 {
inline void _dbg_dumper(csubstr s) { fwrite(s.str, 1, s.len, stdout); };
template<class ...Args>
void _dbg_printf(c4::csubstr fmt, Args&& ...args)
{
    static char writebuf[256];
    auto results = c4::format_dump_resume<&_dbg_dumper>(writebuf, fmt, std::forward<Args>(args)...);
    // resume writing if the results failed to fit the buffer
    if(C4_UNLIKELY(results.bufsize > sizeof(writebuf))) // bufsize will be that of the largest element serialized. Eg int(1), will require 1 byte.
    {
        results = format_dump_resume<&_dbg_dumper>(results, writebuf, fmt, std::forward<Args>(args)...);
        if(C4_UNLIKELY(results.bufsize > sizeof(writebuf)))
        {
            results = format_dump_resume<&_dbg_dumper>(results, writebuf, fmt, std::forward<Args>(args)...);
        }
    }
}
} // namespace c4

#   define _c4dbgt(fmt, ...)   this->_dbg ("{}:{}: "   fmt     , __FILE__, __LINE__, ## __VA_ARGS__)
#   define _c4dbgpf(fmt, ...)  _dbg_printf("{}:{}: "   fmt "\n", __FILE__, __LINE__, ## __VA_ARGS__)
#   define _c4dbgp(msg)        _dbg_printf("{}:{}: "   msg "\n", __FILE__, __LINE__                )
#   define _c4dbgq(msg)        _dbg_printf(msg "\n")
#   define _c4err(fmt, ...)   \
    do { if(c4::is_debugger_attached()) { C4_DEBUG_BREAK(); } \
         this->_err("ERROR:\n" "{}:{}: " fmt, __FILE__, __LINE__, ## __VA_ARGS__); } while(0)
#else
#   define _c4dbgt(fmt, ...)
#   define _c4dbgpf(fmt, ...)
#   define _c4dbgp(msg)
#   define _c4dbgq(msg)
#   define _c4err(fmt, ...)   \
    do { if(c4::is_debugger_attached()) { C4_DEBUG_BREAK(); } \
         this->_err("ERROR: " fmt, ## __VA_ARGS__); } while(0)
#endif

#define _c4prsp(sp) sp
#define _c4presc(s) __c4presc(s.str, s.len)
inline c4::csubstr _c4prc(const char &C4_RESTRICT c)
{
    switch(c)
    {
    case '\n': return c4::csubstr("\\n");
    case '\t': return c4::csubstr("\\t");
    case '\0': return c4::csubstr("\\0");
    case '\r': return c4::csubstr("\\r");
    case '\f': return c4::csubstr("\\f");
    case '\b': return c4::csubstr("\\b");
    case '\v': return c4::csubstr("\\v");
    case '\a': return c4::csubstr("\\a");
    default: return c4::csubstr(&c, 1);
    }
}
inline void __c4presc(const char *s, size_t len)
{
    size_t prev = 0;
    for(size_t i = 0; i < len; ++i)
    {
        switch(s[i])
        {
        case '\n'  : fwrite(s+prev, 1, i-prev, stdout); putchar('\\'); putchar('n'); putchar('\n'); prev = i+1; break;
        case '\t'  : fwrite(s+prev, 1, i-prev, stdout); putchar('\\'); putchar('t'); prev = i+1; break;
        case '\0'  : fwrite(s+prev, 1, i-prev, stdout); putchar('\\'); putchar('0'); prev = i+1; break;
        case '\r'  : fwrite(s+prev, 1, i-prev, stdout); putchar('\\'); putchar('r'); prev = i+1; break;
        case '\f'  : fwrite(s+prev, 1, i-prev, stdout); putchar('\\'); putchar('f'); prev = i+1; break;
        case '\b'  : fwrite(s+prev, 1, i-prev, stdout); putchar('\\'); putchar('b'); prev = i+1; break;
        case '\v'  : fwrite(s+prev, 1, i-prev, stdout); putchar('\\'); putchar('v'); prev = i+1; break;
        case '\a'  : fwrite(s+prev, 1, i-prev, stdout); putchar('\\'); putchar('a'); prev = i+1; break;
        case '\x1b': fwrite(s+prev, 1, i-prev, stdout); putchar('\\'); putchar('e'); prev = i+1; break;
        case -0x3e/*0xc2u*/:
            if(i+1 < len)
            {
                if(s[i+1] == -0x60/*0xa0u*/)
                {
                    fwrite(s+prev, 1, i-prev, stdout); putchar('\\'); putchar('_'); prev = i+2; ++i;
                }
                else if(s[i+1] == -0x7b/*0x85u*/)
                {
                    fwrite(s+prev, 1, i-prev, stdout); putchar('\\'); putchar('N'); prev = i+2; ++i;
                }
                break;
            }
        case -0x1e/*0xe2u*/:
            if(i+2 < len && s[i+1] == -0x80/*0x80u*/)
            {
                if(s[i+2] == -0x58/*0xa8u*/)
                {
                    fwrite(s+prev, 1, i-prev, stdout); putchar('\\'); putchar('L'); prev = i+3; i += 2;
                }
                else if(s[i+2] == -0x57/*0xa9u*/)
                {
                    fwrite(s+prev, 1, i-prev, stdout); putchar('\\'); putchar('P'); prev = i+3; i += 2;
                }
                break;
            }
        }
    }
    fwrite(s + prev, 1, len - prev, stdout);
}

#pragma clang diagnostic pop
#pragma GCC diagnostic pop

#if defined(_MSC_VER)
#   pragma warning(pop)
#endif


#endif /* _C4_YML_DETAIL_PARSER_DBG_HPP_ */


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/detail/parser_dbg.hpp)

#define C4_YML_EMIT_DEF_HPP_



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/emit.hpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/emit.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_YML_EMIT_HPP_
#define _C4_YML_EMIT_HPP_

#ifndef _C4_YML_WRITER_HPP_
#include "./writer.hpp"
#endif

#ifndef _C4_YML_TREE_HPP_
#include "./tree.hpp"
#endif

#ifndef _C4_YML_NODE_HPP_
#include "./node.hpp"
#endif


#define RYML_DEPRECATE_EMIT                                             \
    RYML_DEPRECATED("use emit_yaml() instead. See https://github.com/biojppm/rapidyaml/issues/120")
#ifdef emit
#error "emit is defined, likely from a Qt include. This will cause a compilation error. See https://github.com/biojppm/rapidyaml/issues/120"
#endif
#define RYML_DEPRECATE_EMITRS                                           \
    RYML_DEPRECATED("use emitrs_yaml() instead. See https://github.com/biojppm/rapidyaml/issues/120")


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

namespace c4 {
namespace yml {

template<class Writer> class Emitter;

template<class OStream>
using EmitterOStream = Emitter<WriterOStream<OStream>>;
using EmitterFile = Emitter<WriterFile>;
using EmitterBuf  = Emitter<WriterBuf>;

typedef enum {
    EMIT_YAML = 0,
    EMIT_JSON = 1
} EmitType_e;


/** mark a tree or node to be emitted as json */
struct as_json
{
    Tree const* tree;
    size_t node;
    as_json(Tree const& t) : tree(&t), node(t.empty() ? NONE : t.root_id()) {}
    as_json(Tree const& t, size_t id) : tree(&t), node(id) {}
    as_json(ConstNodeRef const& n) : tree(n.tree()), node(n.id()) {}
};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

template<class Writer>
class Emitter : public Writer
{
public:

    using Writer::Writer;

    /** emit!
     *
     * When writing to a buffer, returns a substr of the emitted YAML.
     * If the given buffer has insufficient space, the returned span will
     * be null and its size will be the needed space. No writes are done
     * after the end of the buffer.
     *
     * When writing to a file, the returned substr will be null, but its
     * length will be set to the number of bytes written. */
    substr emit_as(EmitType_e type, Tree const& t, size_t id, bool error_on_excess);
    /** emit starting at the root node */
    substr emit_as(EmitType_e type, Tree const& t, bool error_on_excess=true);
    /** emit the given node */
    substr emit_as(EmitType_e type, ConstNodeRef const& n, bool error_on_excess=true);

private:

    Tree const* C4_RESTRICT m_tree;

    void _emit_yaml(size_t id);
    void _do_visit_flow_sl(size_t id, size_t ilevel=0);
    void _do_visit_flow_ml(size_t id, size_t ilevel=0, size_t do_indent=1);
    void _do_visit_block(size_t id, size_t ilevel=0, size_t do_indent=1);
    void _do_visit_block_container(size_t id, size_t next_level, size_t do_indent);
    void _do_visit_json(size_t id);

private:

    void _write(NodeScalar const& C4_RESTRICT sc, NodeType flags, size_t level);
    void _write_json(NodeScalar const& C4_RESTRICT sc, NodeType flags);

    void _write_doc(size_t id);
    void _write_scalar(csubstr s, bool was_quoted);
    void _write_scalar_json(csubstr s, bool as_key, bool was_quoted);
    void _write_scalar_literal(csubstr s, size_t level, bool as_key, bool explicit_indentation=false);
    void _write_scalar_folded(csubstr s, size_t level, bool as_key);
    void _write_scalar_squo(csubstr s, size_t level);
    void _write_scalar_dquo(csubstr s, size_t level);
    void _write_scalar_plain(csubstr s, size_t level);

    void _write_tag(csubstr tag)
    {
        if(!tag.begins_with('!'))
            this->Writer::_do_write('!');
        this->Writer::_do_write(tag);
    }

    enum : type_bits {
        _keysc =  (KEY|KEYREF|KEYANCH|KEYQUO|_WIP_KEY_STYLE) | ~(VAL|VALREF|VALANCH|VALQUO|_WIP_VAL_STYLE),
        _valsc = ~(KEY|KEYREF|KEYANCH|KEYQUO|_WIP_KEY_STYLE) |  (VAL|VALREF|VALANCH|VALQUO|_WIP_VAL_STYLE),
        _keysc_json =  (KEY)  | ~(VAL),
        _valsc_json = ~(KEY)  |  (VAL),
    };

    C4_ALWAYS_INLINE void _writek(size_t id, size_t level) { _write(m_tree->keysc(id), m_tree->_p(id)->m_type.type & ~_valsc, level); }
    C4_ALWAYS_INLINE void _writev(size_t id, size_t level) { _write(m_tree->valsc(id), m_tree->_p(id)->m_type.type & ~_keysc, level); }

    C4_ALWAYS_INLINE void _writek_json(size_t id) { _write_json(m_tree->keysc(id), m_tree->_p(id)->m_type.type & ~(VAL)); }
    C4_ALWAYS_INLINE void _writev_json(size_t id) { _write_json(m_tree->valsc(id), m_tree->_p(id)->m_type.type & ~(KEY)); }

};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** emit YAML to the given file. A null file defaults to stdout.
 * Return the number of bytes written. */
inline size_t emit_yaml(Tree const& t, size_t id, FILE *f)
{
    EmitterFile em(f);
    return em.emit_as(EMIT_YAML, t, id, /*error_on_excess*/true).len;
}
RYML_DEPRECATE_EMIT inline size_t emit(Tree const& t, size_t id, FILE *f)
{
    return emit_yaml(t, id, f);
}

/** emit JSON to the given file. A null file defaults to stdout.
 * Return the number of bytes written. */
inline size_t emit_json(Tree const& t, size_t id, FILE *f)
{
    EmitterFile em(f);
    return em.emit_as(EMIT_JSON, t, id, /*error_on_excess*/true).len;
}


/** emit YAML to the given file. A null file defaults to stdout.
 * Return the number of bytes written.
 * @overload */
inline size_t emit_yaml(Tree const& t, FILE *f=nullptr)
{
    EmitterFile em(f);
    return em.emit_as(EMIT_YAML, t, /*error_on_excess*/true).len;
}
RYML_DEPRECATE_EMIT inline size_t emit(Tree const& t, FILE *f=nullptr)
{
    return emit_yaml(t, f);
}

/** emit JSON to the given file. A null file defaults to stdout.
 * Return the number of bytes written.
 * @overload */
inline size_t emit_json(Tree const& t, FILE *f=nullptr)
{
    EmitterFile em(f);
    return em.emit_as(EMIT_JSON, t, /*error_on_excess*/true).len;
}


/** emit YAML to the given file. A null file defaults to stdout.
 * Return the number of bytes written.
 * @overload */
inline size_t emit_yaml(ConstNodeRef const& r, FILE *f=nullptr)
{
    EmitterFile em(f);
    return em.emit_as(EMIT_YAML, r, /*error_on_excess*/true).len;
}
RYML_DEPRECATE_EMIT inline size_t emit(ConstNodeRef const& r, FILE *f=nullptr)
{
    return emit_yaml(r, f);
}

/** emit JSON to the given file. A null file defaults to stdout.
 * Return the number of bytes written.
 * @overload */
inline size_t emit_json(ConstNodeRef const& r, FILE *f=nullptr)
{
    EmitterFile em(f);
    return em.emit_as(EMIT_JSON, r, /*error_on_excess*/true).len;
}


//-----------------------------------------------------------------------------

/** emit YAML to an STL-like ostream */
template<class OStream>
inline OStream& operator<< (OStream& s, Tree const& t)
{
    EmitterOStream<OStream> em(s);
    em.emit_as(EMIT_YAML, t);
    return s;
}

/** emit YAML to an STL-like ostream
 * @overload */
template<class OStream>
inline OStream& operator<< (OStream& s, ConstNodeRef const& n)
{
    EmitterOStream<OStream> em(s);
    em.emit_as(EMIT_YAML, n);
    return s;
}

/** emit json to an STL-like stream */
template<class OStream>
inline OStream& operator<< (OStream& s, as_json const& j)
{
    EmitterOStream<OStream> em(s);
    em.emit_as(EMIT_JSON, *j.tree, j.node, true);
    return s;
}


//-----------------------------------------------------------------------------


/** emit YAML to the given buffer. Return a substr trimmed to the emitted YAML.
 * @param error_on_excess Raise an error if the space in the buffer is insufficient.
 * @overload */
inline substr emit_yaml(Tree const& t, size_t id, substr buf, bool error_on_excess=true)
{
    EmitterBuf em(buf);
    return em.emit_as(EMIT_YAML, t, id, error_on_excess);
}
RYML_DEPRECATE_EMIT inline substr emit(Tree const& t, size_t id, substr buf, bool error_on_excess=true)
{
    return emit_yaml(t, id, buf, error_on_excess);
}

/** emit JSON to the given buffer. Return a substr trimmed to the emitted JSON.
 * @param error_on_excess Raise an error if the space in the buffer is insufficient.
 * @overload */
inline substr emit_json(Tree const& t, size_t id, substr buf, bool error_on_excess=true)
{
    EmitterBuf em(buf);
    return em.emit_as(EMIT_JSON, t, id, error_on_excess);
}


/** emit YAML to the given buffer. Return a substr trimmed to the emitted YAML.
 * @param error_on_excess Raise an error if the space in the buffer is insufficient.
 * @overload */
inline substr emit_yaml(Tree const& t, substr buf, bool error_on_excess=true)
{
    EmitterBuf em(buf);
    return em.emit_as(EMIT_YAML, t, error_on_excess);
}
RYML_DEPRECATE_EMIT inline substr emit(Tree const& t, substr buf, bool error_on_excess=true)
{
    return emit_yaml(t, buf, error_on_excess);
}

/** emit JSON to the given buffer. Return a substr trimmed to the emitted JSON.
 * @param error_on_excess Raise an error if the space in the buffer is insufficient.
 * @overload */
inline substr emit_json(Tree const& t, substr buf, bool error_on_excess=true)
{
    EmitterBuf em(buf);
    return em.emit_as(EMIT_JSON, t, error_on_excess);
}


/** emit YAML to the given buffer. Return a substr trimmed to the emitted YAML.
 * @param error_on_excess Raise an error if the space in the buffer is insufficient.
 * @overload
 */
inline substr emit_yaml(ConstNodeRef const& r, substr buf, bool error_on_excess=true)
{
    EmitterBuf em(buf);
    return em.emit_as(EMIT_YAML, r, error_on_excess);
}
RYML_DEPRECATE_EMIT inline substr emit(ConstNodeRef const& r, substr buf, bool error_on_excess=true)
{
    return emit_yaml(r, buf, error_on_excess);
}

/** emit JSON to the given buffer. Return a substr trimmed to the emitted JSON.
 * @param error_on_excess Raise an error if the space in the buffer is insufficient.
 * @overload
 */
inline substr emit_json(ConstNodeRef const& r, substr buf, bool error_on_excess=true)
{
    EmitterBuf em(buf);
    return em.emit_as(EMIT_JSON, r, error_on_excess);
}


//-----------------------------------------------------------------------------

/** emit+resize: emit YAML to the given std::string/std::vector-like
 * container, resizing it as needed to fit the emitted YAML. */
template<class CharOwningContainer>
substr emitrs_yaml(Tree const& t, size_t id, CharOwningContainer * cont)
{
    substr buf = to_substr(*cont);
    substr ret = emit_yaml(t, id, buf, /*error_on_excess*/false);
    if(ret.str == nullptr && ret.len > 0)
    {
        cont->resize(ret.len);
        buf = to_substr(*cont);
        ret = emit_yaml(t, id, buf, /*error_on_excess*/true);
    }
    return ret;
}
template<class CharOwningContainer>
RYML_DEPRECATE_EMITRS substr emitrs(Tree const& t, size_t id, CharOwningContainer * cont)
{
    return emitrs_yaml(t, id, cont);
}

/** emit+resize: emit JSON to the given std::string/std::vector-like
 * container, resizing it as needed to fit the emitted JSON. */
template<class CharOwningContainer>
substr emitrs_json(Tree const& t, size_t id, CharOwningContainer * cont)
{
    substr buf = to_substr(*cont);
    substr ret = emit_json(t, id, buf, /*error_on_excess*/false);
    if(ret.str == nullptr && ret.len > 0)
    {
        cont->resize(ret.len);
        buf = to_substr(*cont);
        ret = emit_json(t, id, buf, /*error_on_excess*/true);
    }
    return ret;
}


/** emit+resize: emit YAML to the given std::string/std::vector-like
 * container, resizing it as needed to fit the emitted YAML. */
template<class CharOwningContainer>
CharOwningContainer emitrs_yaml(Tree const& t, size_t id)
{
    CharOwningContainer c;
    emitrs_yaml(t, id, &c);
    return c;
}
template<class CharOwningContainer>
RYML_DEPRECATE_EMITRS CharOwningContainer emitrs(Tree const& t, size_t id)
{
    CharOwningContainer c;
    emitrs_yaml(t, id, &c);
    return c;
}

/** emit+resize: emit JSON to the given std::string/std::vector-like
 * container, resizing it as needed to fit the emitted JSON. */
template<class CharOwningContainer>
CharOwningContainer emitrs_json(Tree const& t, size_t id)
{
    CharOwningContainer c;
    emitrs_json(t, id, &c);
    return c;
}


/** emit+resize: YAML to the given std::string/std::vector-like
 * container, resizing it as needed to fit the emitted YAML. */
template<class CharOwningContainer>
substr emitrs_yaml(Tree const& t, CharOwningContainer * cont)
{
    if(t.empty())
        return {};
    return emitrs_yaml(t, t.root_id(), cont);
}
template<class CharOwningContainer>
RYML_DEPRECATE_EMITRS substr emitrs(Tree const& t, CharOwningContainer * cont)
{
    return emitrs_yaml(t, cont);
}

/** emit+resize: JSON to the given std::string/std::vector-like
 * container, resizing it as needed to fit the emitted JSON. */
template<class CharOwningContainer>
substr emitrs_json(Tree const& t, CharOwningContainer * cont)
{
    if(t.empty())
        return {};
    return emitrs_json(t, t.root_id(), cont);
}


/** emit+resize: YAML to the given std::string/std::vector-like container,
 * resizing it as needed to fit the emitted YAML. */
template<class CharOwningContainer>
CharOwningContainer emitrs_yaml(Tree const& t)
{
    CharOwningContainer c;
    if(t.empty())
        return c;
    emitrs_yaml(t, t.root_id(), &c);
    return c;
}
template<class CharOwningContainer>
RYML_DEPRECATE_EMITRS CharOwningContainer emitrs(Tree const& t)
{
    return emitrs_yaml<CharOwningContainer>(t);
}

/** emit+resize: JSON to the given std::string/std::vector-like container,
 * resizing it as needed to fit the emitted JSON. */
template<class CharOwningContainer>
CharOwningContainer emitrs_json(Tree const& t)
{
    CharOwningContainer c;
    if(t.empty())
        return c;
    emitrs_json(t, t.root_id(), &c);
    return c;
}


/** emit+resize: YAML to the given std::string/std::vector-like container,
 * resizing it as needed to fit the emitted YAML. */
template<class CharOwningContainer>
substr emitrs_yaml(ConstNodeRef const& n, CharOwningContainer * cont)
{
    _RYML_CB_CHECK(n.tree()->callbacks(), n.valid());
    return emitrs_yaml(*n.tree(), n.id(), cont);
}
template<class CharOwningContainer>
RYML_DEPRECATE_EMITRS substr emitrs(ConstNodeRef const& n, CharOwningContainer * cont)
{
    return emitrs_yaml(n, cont);
}

/** emit+resize: JSON to the given std::string/std::vector-like container,
 * resizing it as needed to fit the emitted JSON. */
template<class CharOwningContainer>
substr emitrs_json(ConstNodeRef const& n, CharOwningContainer * cont)
{
    _RYML_CB_CHECK(n.tree()->callbacks(), n.valid());
    return emitrs_json(*n.tree(), n.id(), cont);
}


/** emit+resize: YAML to the given std::string/std::vector-like container,
 * resizing it as needed to fit the emitted YAML. */
template<class CharOwningContainer>
CharOwningContainer emitrs_yaml(ConstNodeRef const& n)
{
    _RYML_CB_CHECK(n.tree()->callbacks(), n.valid());
    CharOwningContainer c;
    emitrs_yaml(*n.tree(), n.id(), &c);
    return c;
}
template<class CharOwningContainer>
RYML_DEPRECATE_EMITRS CharOwningContainer emitrs(ConstNodeRef const& n)
{
    return emitrs_yaml<CharOwningContainer>(n);
}

/** emit+resize: JSON to the given std::string/std::vector-like container,
 * resizing it as needed to fit the emitted JSON. */
template<class CharOwningContainer>
CharOwningContainer emitrs_json(ConstNodeRef const& n)
{
    _RYML_CB_CHECK(n.tree()->callbacks(), n.valid());
    CharOwningContainer c;
    emitrs_json(*n.tree(), n.id(), &c);
    return c;
}

} // namespace yml
} // namespace c4

#undef RYML_DEPRECATE_EMIT
#undef RYML_DEPRECATE_EMITRS

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/emit.def.hpp
//#include "c4/yml/emit.def.hpp"
#if !defined(C4_YML_EMIT_DEF_HPP_) && !defined(_C4_YML_EMIT_DEF_HPP_)
#error "amalgamate: file c4/yml/emit.def.hpp must have been included at this point"
#endif /* C4_YML_EMIT_DEF_HPP_ */


#endif /* _C4_YML_EMIT_HPP_ */


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/emit.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/emit.def.hpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/emit.def.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_YML_EMIT_DEF_HPP_
#define _C4_YML_EMIT_DEF_HPP_

#ifndef _C4_YML_EMIT_HPP_
// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/emit.hpp
//#include "c4/yml/emit.hpp"
#if !defined(C4_YML_EMIT_HPP_) && !defined(_C4_YML_EMIT_HPP_)
#error "amalgamate: file c4/yml/emit.hpp must have been included at this point"
#endif /* C4_YML_EMIT_HPP_ */

#endif

namespace c4 {
namespace yml {

template<class Writer>
substr Emitter<Writer>::emit_as(EmitType_e type, Tree const& t, size_t id, bool error_on_excess)
{
    if(t.empty())
    {
        _RYML_CB_ASSERT(t.callbacks(), id == NONE);
        return {};
    }
    _RYML_CB_CHECK(t.callbacks(), id < t.size());
    m_tree = &t;
    if(type == EMIT_YAML)
        _emit_yaml(id);
    else if(type == EMIT_JSON)
        _do_visit_json(id);
    else
        _RYML_CB_ERR(m_tree->callbacks(), "unknown emit type");
    return this->Writer::_get(error_on_excess);
}

template<class Writer>
substr Emitter<Writer>::emit_as(EmitType_e type, Tree const& t, bool error_on_excess)
{
    if(t.empty())
        return {};
    return this->emit_as(type, t, t.root_id(), error_on_excess);
}

template<class Writer>
substr Emitter<Writer>::emit_as(EmitType_e type, ConstNodeRef const& n, bool error_on_excess)
{
    _RYML_CB_CHECK(n.tree()->callbacks(), n.valid());
    return this->emit_as(type, *n.tree(), n.id(), error_on_excess);
}


//-----------------------------------------------------------------------------

template<class Writer>
void Emitter<Writer>::_emit_yaml(size_t id)
{
    // save branches in the visitor by doing the initial stream/doc
    // logic here, sparing the need to check stream/val/keyval inside
    // the visitor functions
    auto dispatch = [this](size_t node){
        NodeType ty = m_tree->type(node);
        if(ty.marked_flow_sl())
            _do_visit_flow_sl(node, 0);
        else if(ty.marked_flow_ml())
            _do_visit_flow_ml(node, 0);
        else
        {
            _do_visit_block(node, 0);
        }
    };
    if(!m_tree->is_root(id))
    {
        if(m_tree->is_container(id) && !m_tree->type(id).marked_flow())
        {
            size_t ilevel = 0;
            if(m_tree->has_key(id))
            {
                this->Writer::_do_write(m_tree->key(id));
                this->Writer::_do_write(":\n");
                ++ilevel;
            }
            _do_visit_block_container(id, ilevel, ilevel);
            return;
        }
    }

    auto *btd = m_tree->tag_directives().b;
    auto *etd = m_tree->tag_directives().e;
    auto write_tag_directives = [&btd, etd, this](size_t next_node){
        auto end = btd;
        while(end < etd)
        {
            if(end->next_node_id > next_node)
                break;
            ++end;
        }
        for( ; btd != end; ++btd)
        {
            if(next_node != m_tree->first_child(m_tree->parent(next_node)))
                this->Writer::_do_write("...\n");
            this->Writer::_do_write("%TAG ");
            this->Writer::_do_write(btd->handle);
            this->Writer::_do_write(' ');
            this->Writer::_do_write(btd->prefix);
            this->Writer::_do_write('\n');
        }
    };
    if(m_tree->is_stream(id))
    {
        if(m_tree->first_child(id) != NONE)
            write_tag_directives(m_tree->first_child(id));
        for(size_t child = m_tree->first_child(id); child != NONE; child = m_tree->next_sibling(child))
        {
            dispatch(child);
            if(m_tree->next_sibling(child) != NONE)
                write_tag_directives(m_tree->next_sibling(child));
        }
    }
    else if(m_tree->is_container(id))
    {
        dispatch(id);
    }
    else if(m_tree->is_doc(id))
    {
        _RYML_CB_ASSERT(m_tree->callbacks(), !m_tree->is_container(id)); // checked above
        _RYML_CB_ASSERT(m_tree->callbacks(), m_tree->is_val(id)); // so it must be a val
        _write_doc(id);
    }
    else if(m_tree->is_keyval(id))
    {
        _writek(id, 0);
        this->Writer::_do_write(": ");
        _writev(id, 0);
        if(!m_tree->type(id).marked_flow())
            this->Writer::_do_write('\n');
    }
    else if(m_tree->is_val(id))
    {
        //this->Writer::_do_write("- ");
        _writev(id, 0);
        if(!m_tree->type(id).marked_flow())
            this->Writer::_do_write('\n');
    }
    else if(m_tree->type(id) == NOTYPE)
    {
        ;
    }
    else
    {
        _RYML_CB_ERR(m_tree->callbacks(), "unknown type");
    }
}

template<class Writer>
void Emitter<Writer>::_write_doc(size_t id)
{
    RYML_ASSERT(m_tree->is_doc(id));
    if(!m_tree->is_root(id))
    {
        RYML_ASSERT(m_tree->is_stream(m_tree->parent(id)));
        this->Writer::_do_write("---");
    }
    if(!m_tree->has_val(id)) // this is more frequent
    {
        if(m_tree->has_val_tag(id))
        {
            if(!m_tree->is_root(id))
                this->Writer::_do_write(' ');
            _write_tag(m_tree->val_tag(id));
        }
        if(m_tree->has_val_anchor(id))
        {
            if(!m_tree->is_root(id))
                this->Writer::_do_write(' ');
            this->Writer::_do_write('&');
            this->Writer::_do_write(m_tree->val_anchor(id));
        }
    }
    else // docval
    {
        RYML_ASSERT(m_tree->has_val(id));
        RYML_ASSERT(!m_tree->has_key(id));
        if(!m_tree->is_root(id))
            this->Writer::_do_write(' ');
        _writev(id, 0);
    }
    this->Writer::_do_write('\n');
}

template<class Writer>
void Emitter<Writer>::_do_visit_flow_sl(size_t node, size_t ilevel)
{
    RYML_ASSERT(!m_tree->is_stream(node));
    RYML_ASSERT(m_tree->is_container(node) || m_tree->is_doc(node));
    RYML_ASSERT(m_tree->is_root(node) || (m_tree->parent_is_map(node) || m_tree->parent_is_seq(node)));

    if(m_tree->is_doc(node))
    {
        _write_doc(node);
        if(!m_tree->has_children(node))
            return;
    }
    else if(m_tree->is_container(node))
    {
        RYML_ASSERT(m_tree->is_map(node) || m_tree->is_seq(node));

        bool spc = false; // write a space

        if(m_tree->has_key(node))
        {
            _writek(node, ilevel);
            this->Writer::_do_write(':');
            spc = true;
        }

        if(m_tree->has_val_tag(node))
        {
            if(spc)
                this->Writer::_do_write(' ');
            _write_tag(m_tree->val_tag(node));
            spc = true;
        }

        if(m_tree->has_val_anchor(node))
        {
            if(spc)
                this->Writer::_do_write(' ');
            this->Writer::_do_write('&');
            this->Writer::_do_write(m_tree->val_anchor(node));
            spc = true;
        }

        if(spc)
            this->Writer::_do_write(' ');

        if(m_tree->is_map(node))
        {
            this->Writer::_do_write('{');
        }
        else
        {
            _RYML_CB_ASSERT(m_tree->callbacks(), m_tree->is_seq(node));
            this->Writer::_do_write('[');
        }
    } // container

    for(size_t child = m_tree->first_child(node), count = 0; child != NONE; child = m_tree->next_sibling(child))
    {
        if(count++)
            this->Writer::_do_write(',');
        if(m_tree->is_keyval(child))
        {
            _writek(child, ilevel);
            this->Writer::_do_write(": ");
            _writev(child, ilevel);
        }
        else if(m_tree->is_val(child))
        {
            _writev(child, ilevel);
        }
        else
        {
            // with single-line flow, we can never go back to block
            _do_visit_flow_sl(child, ilevel + 1);
        }
    }

    if(m_tree->is_map(node))
    {
        this->Writer::_do_write('}');
    }
    else if(m_tree->is_seq(node))
    {
        this->Writer::_do_write(']');
    }
}

template<class Writer>
void Emitter<Writer>::_do_visit_flow_ml(size_t id, size_t ilevel, size_t do_indent)
{
    C4_UNUSED(id);
    C4_UNUSED(ilevel);
    C4_UNUSED(do_indent);
    RYML_CHECK(false/*not implemented*/);
}

template<class Writer>
void Emitter<Writer>::_do_visit_block_container(size_t node, size_t next_level, size_t do_indent)
{
    RepC ind = indent_to(do_indent * next_level);

    if(m_tree->is_seq(node))
    {
        for(size_t child = m_tree->first_child(node); child != NONE; child = m_tree->next_sibling(child))
        {
            _RYML_CB_ASSERT(m_tree->callbacks(), !m_tree->has_key(child));
            if(m_tree->is_val(child))
            {
                this->Writer::_do_write(ind);
                this->Writer::_do_write("- ");
                _writev(child, next_level);
                this->Writer::_do_write('\n');
            }
            else
            {
                _RYML_CB_ASSERT(m_tree->callbacks(), m_tree->is_container(child));
                NodeType ty = m_tree->type(child);
                if(ty.marked_flow_sl())
                {
                    this->Writer::_do_write(ind);
                    this->Writer::_do_write("- ");
                    _do_visit_flow_sl(child, 0u);
                    this->Writer::_do_write('\n');
                }
                else if(ty.marked_flow_ml())
                {
                    this->Writer::_do_write(ind);
                    this->Writer::_do_write("- ");
                    _do_visit_flow_ml(child, next_level, do_indent);
                    this->Writer::_do_write('\n');
                }
                else
                {
                    _do_visit_block(child, next_level, do_indent);
                }
            }
            do_indent = true;
            ind = indent_to(do_indent * next_level);
        }
    }
    else // map
    {
        _RYML_CB_ASSERT(m_tree->callbacks(), m_tree->is_map(node));
        for(size_t ich = m_tree->first_child(node); ich != NONE; ich = m_tree->next_sibling(ich))
        {
            _RYML_CB_ASSERT(m_tree->callbacks(), m_tree->has_key(ich));
            if(m_tree->is_keyval(ich))
            {
                this->Writer::_do_write(ind);
                _writek(ich, next_level);
                this->Writer::_do_write(": ");
                _writev(ich, next_level);
                this->Writer::_do_write('\n');
            }
            else
            {
                _RYML_CB_ASSERT(m_tree->callbacks(), m_tree->is_container(ich));
                NodeType ty = m_tree->type(ich);
                if(ty.marked_flow_sl())
                {
                    this->Writer::_do_write(ind);
                    _do_visit_flow_sl(ich, 0u);
                    this->Writer::_do_write('\n');
                }
                else if(ty.marked_flow_ml())
                {
                    this->Writer::_do_write(ind);
                    _do_visit_flow_ml(ich, 0u);
                    this->Writer::_do_write('\n');
                }
                else
                {
                    _do_visit_block(ich, next_level, do_indent);
                }
            }
            do_indent = true;
            ind = indent_to(do_indent * next_level);
        }
    }
}

template<class Writer>
void Emitter<Writer>::_do_visit_block(size_t node, size_t ilevel, size_t do_indent)
{
    RYML_ASSERT(!m_tree->is_stream(node));
    RYML_ASSERT(m_tree->is_container(node) || m_tree->is_doc(node));
    RYML_ASSERT(m_tree->is_root(node) || (m_tree->parent_is_map(node) || m_tree->parent_is_seq(node)));
    RepC ind = indent_to(do_indent * ilevel);

    if(m_tree->is_doc(node))
    {
        _write_doc(node);
        if(!m_tree->has_children(node))
            return;
    }
    else if(m_tree->is_container(node))
    {
        RYML_ASSERT(m_tree->is_map(node) || m_tree->is_seq(node));

        bool spc = false; // write a space
        bool nl = false;  // write a newline

        if(m_tree->has_key(node))
        {
            this->Writer::_do_write(ind);
            _writek(node, ilevel);
            this->Writer::_do_write(':');
            spc = true;
        }
        else if(!m_tree->is_root(node))
        {
            this->Writer::_do_write(ind);
            this->Writer::_do_write('-');
            spc = true;
        }

        if(m_tree->has_val_tag(node))
        {
            if(spc)
                this->Writer::_do_write(' ');
            _write_tag(m_tree->val_tag(node));
            spc = true;
            nl = true;
        }

        if(m_tree->has_val_anchor(node))
        {
            if(spc)
                this->Writer::_do_write(' ');
            this->Writer::_do_write('&');
            this->Writer::_do_write(m_tree->val_anchor(node));
            spc = true;
            nl = true;
        }

        if(m_tree->has_children(node))
        {
            if(m_tree->has_key(node))
                nl = true;
            else
                if(!m_tree->is_root(node) && !nl)
                    spc = true;
        }
        else
        {
            if(m_tree->is_seq(node))
                this->Writer::_do_write(" []\n");
            else if(m_tree->is_map(node))
                this->Writer::_do_write(" {}\n");
            return;
        }

        if(spc && !nl)
            this->Writer::_do_write(' ');

        do_indent = 0;
        if(nl)
        {
            this->Writer::_do_write('\n');
            do_indent = 1;
        }
    } // container

    size_t next_level = ilevel + 1;
    if(m_tree->is_root(node) || m_tree->is_doc(node))
        next_level = ilevel; // do not indent at top level

    _do_visit_block_container(node, next_level, do_indent);
}

template<class Writer>
void Emitter<Writer>::_do_visit_json(size_t id)
{
    _RYML_CB_CHECK(m_tree->callbacks(), !m_tree->is_stream(id)); // JSON does not have streams
    if(m_tree->is_keyval(id))
    {
        _writek_json(id);
        this->Writer::_do_write(": ");
        _writev_json(id);
    }
    else if(m_tree->is_val(id))
    {
        _writev_json(id);
    }
    else if(m_tree->is_container(id))
    {
        if(m_tree->has_key(id))
        {
            _writek_json(id);
            this->Writer::_do_write(": ");
        }
        if(m_tree->is_seq(id))
            this->Writer::_do_write('[');
        else if(m_tree->is_map(id))
            this->Writer::_do_write('{');
    }  // container

    for(size_t ich = m_tree->first_child(id); ich != NONE; ich = m_tree->next_sibling(ich))
    {
        if(ich != m_tree->first_child(id))
            this->Writer::_do_write(',');
        _do_visit_json(ich);
    }

    if(m_tree->is_seq(id))
        this->Writer::_do_write(']');
    else if(m_tree->is_map(id))
        this->Writer::_do_write('}');
}

template<class Writer>
void Emitter<Writer>::_write(NodeScalar const& C4_RESTRICT sc, NodeType flags, size_t ilevel)
{
    if( ! sc.tag.empty())
    {
        _write_tag(sc.tag);
        this->Writer::_do_write(' ');
    }
    if(flags.has_anchor())
    {
        RYML_ASSERT(flags.is_ref() != flags.has_anchor());
        RYML_ASSERT( ! sc.anchor.empty());
        this->Writer::_do_write('&');
        this->Writer::_do_write(sc.anchor);
        this->Writer::_do_write(' ');
    }
    else if(flags.is_ref())
    {
        if(sc.anchor != "<<")
            this->Writer::_do_write('*');
        this->Writer::_do_write(sc.anchor);
        return;
    }

    // ensure the style flags only have one of KEY or VAL
    _RYML_CB_ASSERT(m_tree->callbacks(), ((flags & (_WIP_KEY_STYLE|_WIP_VAL_STYLE)) == 0) || (((flags&_WIP_KEY_STYLE) == 0) != ((flags&_WIP_VAL_STYLE) == 0)));

    auto style_marks = flags & (_WIP_KEY_STYLE|_WIP_VAL_STYLE);
    if(style_marks & (_WIP_KEY_LITERAL|_WIP_VAL_LITERAL))
    {
        _write_scalar_literal(sc.scalar, ilevel, flags.has_key());
    }
    else if(style_marks & (_WIP_KEY_FOLDED|_WIP_VAL_FOLDED))
    {
        _write_scalar_folded(sc.scalar, ilevel, flags.has_key());
    }
    else if(style_marks & (_WIP_KEY_SQUO|_WIP_VAL_SQUO))
    {
        _write_scalar_squo(sc.scalar, ilevel);
    }
    else if(style_marks & (_WIP_KEY_DQUO|_WIP_VAL_DQUO))
    {
        _write_scalar_dquo(sc.scalar, ilevel);
    }
    else if(style_marks & (_WIP_KEY_PLAIN|_WIP_VAL_PLAIN))
    {
        _write_scalar_plain(sc.scalar, ilevel);
    }
    else if(!style_marks)
    {
        size_t first_non_nl = sc.scalar.first_not_of('\n');
        bool all_newlines = first_non_nl == npos;
        bool has_leading_ws = (!all_newlines) && sc.scalar.sub(first_non_nl).begins_with_any(" \t");
        bool do_literal = ((!sc.scalar.empty() && all_newlines) || (has_leading_ws && !sc.scalar.trim(' ').empty()));
        if(do_literal)
        {
            _write_scalar_literal(sc.scalar, ilevel, flags.has_key(), /*explicit_indentation*/has_leading_ws);
        }
        else
        {
            for(size_t i = 0; i < sc.scalar.len; ++i)
            {
                if(sc.scalar.str[i] == '\n')
                {
                    _write_scalar_literal(sc.scalar, ilevel, flags.has_key(), /*explicit_indentation*/has_leading_ws);
                    goto wrote_special;
                }
                // todo: check for escaped characters requiring double quotes
            }
            _write_scalar(sc.scalar, flags.is_quoted());
        wrote_special:
            ;
        }
    }
    else
    {
        _RYML_CB_ERR(m_tree->callbacks(), "not implemented");
    }
}
template<class Writer>
void Emitter<Writer>::_write_json(NodeScalar const& C4_RESTRICT sc, NodeType flags)
{
    if(C4_UNLIKELY( ! sc.tag.empty()))
        _RYML_CB_ERR(m_tree->callbacks(), "JSON does not have tags");
    if(C4_UNLIKELY(flags.has_anchor()))
        _RYML_CB_ERR(m_tree->callbacks(), "JSON does not have anchors");
    _write_scalar_json(sc.scalar, flags.has_key(), flags.is_quoted());
}

#define _rymlindent_nextline() for(size_t lv = 0; lv < ilevel+1; ++lv) { this->Writer::_do_write(' '); this->Writer::_do_write(' '); }

template<class Writer>
void Emitter<Writer>::_write_scalar_literal(csubstr s, size_t ilevel, bool explicit_key, bool explicit_indentation)
{
    if(explicit_key)
        this->Writer::_do_write("? ");
    csubstr trimmed = s.trimr("\n\r");
    size_t numnewlines_at_end = s.len - trimmed.len - s.sub(trimmed.len).count('\r');
    //
    if(!explicit_indentation)
        this->Writer::_do_write('|');
    else
        this->Writer::_do_write("|2");
    //
    if(numnewlines_at_end > 1 || (trimmed.len == 0 && s.len > 0)/*only newlines*/)
        this->Writer::_do_write("+\n");
    else if(numnewlines_at_end == 1)
        this->Writer::_do_write('\n');
    else
        this->Writer::_do_write("-\n");
    //
    if(trimmed.len)
    {
        size_t pos = 0; // tracks the last character that was already written
        for(size_t i = 0; i < trimmed.len; ++i)
        {
            if(trimmed[i] != '\n')
                continue;
            // write everything up to this point
            csubstr since_pos = trimmed.range(pos, i+1); // include the newline
            _rymlindent_nextline()
            this->Writer::_do_write(since_pos);
            pos = i+1; // already written
        }
        if(pos < trimmed.len)
        {
            _rymlindent_nextline()
            this->Writer::_do_write(trimmed.sub(pos));
        }
        if(numnewlines_at_end)
        {
            this->Writer::_do_write('\n');
            --numnewlines_at_end;
        }
    }
    for(size_t i = 0; i < numnewlines_at_end; ++i)
    {
        _rymlindent_nextline()
        if(i+1 < numnewlines_at_end || explicit_key)
            this->Writer::_do_write('\n');
    }
    if(explicit_key && !numnewlines_at_end)
        this->Writer::_do_write('\n');
}

template<class Writer>
void Emitter<Writer>::_write_scalar_folded(csubstr s, size_t ilevel, bool explicit_key)
{
    if(explicit_key)
    {
        this->Writer::_do_write("? ");
    }
    RYML_ASSERT(s.find("\r") == csubstr::npos);
    csubstr trimmed = s.trimr('\n');
    size_t numnewlines_at_end = s.len - trimmed.len;
    if(numnewlines_at_end == 0)
    {
        this->Writer::_do_write(">-\n");
    }
    else if(numnewlines_at_end == 1)
    {
        this->Writer::_do_write(">\n");
    }
    else if(numnewlines_at_end > 1)
    {
        this->Writer::_do_write(">+\n");
    }
    if(trimmed.len)
    {
        size_t pos = 0; // tracks the last character that was already written
        for(size_t i = 0; i < trimmed.len; ++i)
        {
            if(trimmed[i] != '\n')
                continue;
            // write everything up to this point
            csubstr since_pos = trimmed.range(pos, i+1); // include the newline
            pos = i+1; // because of the newline
            _rymlindent_nextline()
            this->Writer::_do_write(since_pos);
            this->Writer::_do_write('\n'); // write the newline twice
        }
        if(pos < trimmed.len)
        {
            _rymlindent_nextline()
            this->Writer::_do_write(trimmed.sub(pos));
        }
        if(numnewlines_at_end)
        {
            this->Writer::_do_write('\n');
            --numnewlines_at_end;
        }
    }
    for(size_t i = 0; i < numnewlines_at_end; ++i)
    {
        _rymlindent_nextline()
        if(i+1 < numnewlines_at_end || explicit_key)
            this->Writer::_do_write('\n');
    }
    if(explicit_key && !numnewlines_at_end)
        this->Writer::_do_write('\n');
}

template<class Writer>
void Emitter<Writer>::_write_scalar_squo(csubstr s, size_t ilevel)
{
    size_t pos = 0; // tracks the last character that was already written
    this->Writer::_do_write('\'');
    for(size_t i = 0; i < s.len; ++i)
    {
        if(s[i] == '\n')
        {
            csubstr sub = s.range(pos, i+1);
            this->Writer::_do_write(sub);  // write everything up to (including) this char
            this->Writer::_do_write('\n'); // write the character again
            if(i + 1 < s.len)
                _rymlindent_nextline()     // indent the next line
            pos = i+1;
        }
        else if(s[i] == '\'')
        {
            csubstr sub = s.range(pos, i+1);
            this->Writer::_do_write(sub); // write everything up to (including) this char
            this->Writer::_do_write('\''); // write the character again
            pos = i+1;
        }
    }
    // write missing characters at the end of the string
    if(pos < s.len)
        this->Writer::_do_write(s.sub(pos));
    this->Writer::_do_write('\'');
}

template<class Writer>
void Emitter<Writer>::_write_scalar_dquo(csubstr s, size_t ilevel)
{
    size_t pos = 0; // tracks the last character that was already written
    this->Writer::_do_write('"');
    for(size_t i = 0; i < s.len; ++i)
    {
        const char curr = s.str[i];
        if(curr == '"' || curr == '\\')
        {
            csubstr sub = s.range(pos, i);
            this->Writer::_do_write(sub);  // write everything up to (excluding) this char
            this->Writer::_do_write('\\'); // write the escape
            this->Writer::_do_write(curr); // write the char
            pos = i+1;
        }
        else if(s[i] == '\n')
        {
            csubstr sub = s.range(pos, i+1);
            this->Writer::_do_write(sub);  // write everything up to (including) this newline
            this->Writer::_do_write('\n'); // write the newline again
            if(i + 1 < s.len)
                _rymlindent_nextline()     // indent the next line
            pos = i+1;
            if(i+1 < s.len) // escape leading whitespace after the newline
            {
                const char next = s.str[i+1];
                if(next == ' ' || next == '\t')
                    this->Writer::_do_write('\\');
            }
        }
        else if(curr == ' ' || curr == '\t')
        {
            // escape trailing whitespace before a newline
            size_t next = s.first_not_of(" \t\r", i);
            if(next != npos && s[next] == '\n')
            {
                csubstr sub = s.range(pos, i);
                this->Writer::_do_write(sub);  // write everything up to (excluding) this char
                this->Writer::_do_write('\\'); // escape the whitespace
                pos = i;
            }
        }
        else if(C4_UNLIKELY(curr == '\r'))
        {
            csubstr sub = s.range(pos, i);
            this->Writer::_do_write(sub);  // write everything up to (excluding) this char
            this->Writer::_do_write("\\r"); // write the escaped char
            pos = i+1;
        }
    }
    // write missing characters at the end of the string
    if(pos < s.len)
    {
        csubstr sub = s.sub(pos);
        this->Writer::_do_write(sub);
    }
    this->Writer::_do_write('"');
}

template<class Writer>
void Emitter<Writer>::_write_scalar_plain(csubstr s, size_t ilevel)
{
    size_t pos = 0; // tracks the last character that was already written
    for(size_t i = 0; i < s.len; ++i)
    {
        const char curr = s.str[i];
        if(curr == '\n')
        {
            csubstr sub = s.range(pos, i+1);
            this->Writer::_do_write(sub);  // write everything up to (including) this newline
            this->Writer::_do_write('\n'); // write the newline again
            if(i + 1 < s.len)
                _rymlindent_nextline()     // indent the next line
            pos = i+1;
        }
    }
    // write missing characters at the end of the string
    if(pos < s.len)
    {
        csubstr sub = s.sub(pos);
        this->Writer::_do_write(sub);
    }
}

#undef _rymlindent_nextline

template<class Writer>
void Emitter<Writer>::_write_scalar(csubstr s, bool was_quoted)
{
    // this block of code needed to be moved to before the needs_quotes
    // assignment to work around a g++ optimizer bug where (s.str != nullptr)
    // was evaluated as true even if s.str was actually a nullptr (!!!)
    if(s.len == size_t(0))
    {
        if(was_quoted || s.str != nullptr)
            this->Writer::_do_write("''");
        return;
    }

    const bool needs_quotes = (
        was_quoted
        ||
        (
            ( ! s.is_number())
            &&
            (
                // has leading whitespace
                // looks like reference or anchor
                // would be treated as a directive
                // see https://www.yaml.info/learn/quote.html#noplain
                s.begins_with_any(" \n\t\r*&%@`")
                ||
                s.begins_with("<<")
                ||
                // has trailing whitespace
                s.ends_with_any(" \n\t\r")
                ||
                // has special chars
                (s.first_of("#:-?,\n{}[]'\"") != npos)
            )
        )
    );

    if( ! needs_quotes)
    {
        this->Writer::_do_write(s);
    }
    else
    {
        const bool has_dquotes = s.first_of( '"') != npos;
        const bool has_squotes = s.first_of('\'') != npos;
        if(!has_squotes && has_dquotes)
        {
            this->Writer::_do_write('\'');
            this->Writer::_do_write(s);
            this->Writer::_do_write('\'');
        }
        else if(has_squotes && !has_dquotes)
        {
            RYML_ASSERT(s.count('\n') == 0);
            this->Writer::_do_write('"');
            this->Writer::_do_write(s);
            this->Writer::_do_write('"');
        }
        else
        {
            _write_scalar_squo(s, /*FIXME FIXME FIXME*/0);
        }
    }
}
template<class Writer>
void Emitter<Writer>::_write_scalar_json(csubstr s, bool as_key, bool use_quotes)
{
    if((!use_quotes)
       // json keys require quotes
       && (!as_key)
       && (
           // do not quote special cases
           (s == "true" || s == "false" || s == "null")
           || (
               // do not quote numbers
               (s.is_number()
                && (
                    // quote integral numbers if they have a leading 0
                    // https://github.com/biojppm/rapidyaml/issues/291
                    (!(s.len > 1 && s.begins_with('0')))
                    // do not quote reals with leading 0
                    // https://github.com/biojppm/rapidyaml/issues/313
                    || (s.find('.') != csubstr::npos) ))
               )
           )
        )
    {
        this->Writer::_do_write(s);
    }
    else
    {
        size_t pos = 0;
        this->Writer::_do_write('"');
        for(size_t i = 0; i < s.len; ++i)
        {
            switch(s.str[i])
            {
            case '"':
              this->Writer ::_do_write(s.range(pos, i));
              this->Writer ::_do_write("\\\"");
              pos = i + 1;
              break;
            case '\n':
              this->Writer ::_do_write(s.range(pos, i));
              this->Writer ::_do_write("\\n");
              pos = i + 1;
              break;
            case '\t':
              this->Writer ::_do_write(s.range(pos, i));
              this->Writer ::_do_write("\\t");
              pos = i + 1;
              break;
            case '\\':
              this->Writer ::_do_write(s.range(pos, i));
              this->Writer ::_do_write("\\\\");
              pos = i + 1;
              break;
            case '\r':
              this->Writer ::_do_write(s.range(pos, i));
              this->Writer ::_do_write("\\r");
              pos = i + 1;
              break;
            case '\b':
              this->Writer ::_do_write(s.range(pos, i));
              this->Writer ::_do_write("\\b");
              pos = i + 1;
              break;
            case '\f':
              this->Writer ::_do_write(s.range(pos, i));
              this->Writer ::_do_write("\\f");
              pos = i + 1;
              break;
            }
        }
        if(pos < s.len)
        {
            csubstr sub = s.sub(pos);
            this->Writer::_do_write(sub);
        }
        this->Writer::_do_write('"');
    }
}

} // namespace yml
} // namespace c4

#endif /* _C4_YML_EMIT_DEF_HPP_ */


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/emit.def.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/detail/stack.hpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/detail/stack.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_YML_DETAIL_STACK_HPP_
#define _C4_YML_DETAIL_STACK_HPP_

#ifndef _C4_YML_COMMON_HPP_
//included above:
//#include "../common.hpp"
#endif

#ifdef RYML_DBG
//included above:
//#   include <type_traits>
#endif

//included above:
//#include <string.h>

namespace c4 {
namespace yml {
namespace detail {

/** A lightweight contiguous stack with SSO. This avoids a dependency on std. */
template<class T, size_t N=16>
class stack
{
    static_assert(std::is_trivially_copyable<T>::value, "T must be trivially copyable");
    static_assert(std::is_trivially_destructible<T>::value, "T must be trivially destructible");

    enum : size_t { sso_size = N };

public:

    T         m_buf[N];
    T *       m_stack;
    size_t    m_size;
    size_t    m_capacity;
    Callbacks m_callbacks;

public:

    constexpr static bool is_contiguous() { return true; }

    stack(Callbacks const& cb)
        : m_buf()
        , m_stack(m_buf)
        , m_size(0)
        , m_capacity(N)
        , m_callbacks(cb) {}
    stack() : stack(get_callbacks()) {}
    ~stack()
    {
        _free();
    }

    stack(stack const& that) noexcept : stack(that.m_callbacks)
    {
        resize(that.m_size);
        _cp(&that);
    }

    stack(stack &&that) noexcept : stack(that.m_callbacks)
    {
        _mv(&that);
    }

    stack& operator= (stack const& that) noexcept
    {
        _cb(that.m_callbacks);
        resize(that.m_size);
        _cp(&that);
        return *this;
    }

    stack& operator= (stack &&that) noexcept
    {
        _cb(that.m_callbacks);
        _mv(&that);
        return *this;
    }

public:

    size_t size() const { return m_size; }
    size_t empty() const { return m_size == 0; }
    size_t capacity() const { return m_capacity; }

    void clear()
    {
        m_size = 0;
    }

    void resize(size_t sz)
    {
        reserve(sz);
        m_size = sz;
    }

    void reserve(size_t sz);

    void push(T const& C4_RESTRICT n)
    {
        RYML_ASSERT((const char*)&n + sizeof(T) < (const char*)m_stack || &n > m_stack + m_capacity);
        if(m_size == m_capacity)
        {
            size_t cap = m_capacity == 0 ? N : 2 * m_capacity;
            reserve(cap);
        }
        m_stack[m_size] = n;
        ++m_size;
    }

    void push_top()
    {
        RYML_ASSERT(m_size > 0);
        if(m_size == m_capacity)
        {
            size_t cap = m_capacity == 0 ? N : 2 * m_capacity;
            reserve(cap);
        }
        m_stack[m_size] = m_stack[m_size - 1];
        ++m_size;
    }

    T const& C4_RESTRICT pop()
    {
        RYML_ASSERT(m_size > 0);
        --m_size;
        return m_stack[m_size];
    }

    C4_ALWAYS_INLINE T const& C4_RESTRICT top() const { RYML_ASSERT(m_size > 0); return m_stack[m_size - 1]; }
    C4_ALWAYS_INLINE T      & C4_RESTRICT top()       { RYML_ASSERT(m_size > 0); return m_stack[m_size - 1]; }

    C4_ALWAYS_INLINE T const& C4_RESTRICT bottom() const { RYML_ASSERT(m_size > 0); return m_stack[0]; }
    C4_ALWAYS_INLINE T      & C4_RESTRICT bottom()       { RYML_ASSERT(m_size > 0); return m_stack[0]; }

    C4_ALWAYS_INLINE T const& C4_RESTRICT top(size_t i) const { RYML_ASSERT(i < m_size); return m_stack[m_size - 1 - i]; }
    C4_ALWAYS_INLINE T      & C4_RESTRICT top(size_t i)       { RYML_ASSERT(i < m_size); return m_stack[m_size - 1 - i]; }

    C4_ALWAYS_INLINE T const& C4_RESTRICT bottom(size_t i) const { RYML_ASSERT(i < m_size); return m_stack[i]; }
    C4_ALWAYS_INLINE T      & C4_RESTRICT bottom(size_t i)       { RYML_ASSERT(i < m_size); return m_stack[i]; }

    C4_ALWAYS_INLINE T const& C4_RESTRICT operator[](size_t i) const { RYML_ASSERT(i < m_size); return m_stack[i]; }
    C4_ALWAYS_INLINE T      & C4_RESTRICT operator[](size_t i)       { RYML_ASSERT(i < m_size); return m_stack[i]; }

public:

    using       iterator = T       *;
    using const_iterator = T const *;

    iterator begin() { return m_stack; }
    iterator end  () { return m_stack + m_size; }

    const_iterator begin() const { return (const_iterator)m_stack; }
    const_iterator end  () const { return (const_iterator)m_stack + m_size; }

public:
    void _free();
    void _cp(stack const* C4_RESTRICT that);
    void _mv(stack * that);
    void _cb(Callbacks const& cb);
};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

template<class T, size_t N>
void stack<T, N>::reserve(size_t sz)
{
    if(sz <= m_size)
        return;
    if(sz <= N)
    {
        m_stack = m_buf;
        m_capacity = N;
        return;
    }
    T *buf = (T*) m_callbacks.m_allocate(sz * sizeof(T), m_stack, m_callbacks.m_user_data);
    memcpy(buf, m_stack, m_size * sizeof(T));
    if(m_stack != m_buf)
    {
        m_callbacks.m_free(m_stack, m_capacity * sizeof(T), m_callbacks.m_user_data);
    }
    m_stack = buf;
    m_capacity = sz;
}


//-----------------------------------------------------------------------------

template<class T, size_t N>
void stack<T, N>::_free()
{
    RYML_ASSERT(m_stack != nullptr); // this structure cannot be memset() to zero
    if(m_stack != m_buf)
    {
        m_callbacks.m_free(m_stack, m_capacity * sizeof(T), m_callbacks.m_user_data);
        m_stack = m_buf;
        m_size = N;
        m_capacity = N;
    }
    else
    {
        RYML_ASSERT(m_capacity == N);
    }
}


//-----------------------------------------------------------------------------

template<class T, size_t N>
void stack<T, N>::_cp(stack const* C4_RESTRICT that)
{
    if(that->m_stack != that->m_buf)
    {
        RYML_ASSERT(that->m_capacity > N);
        RYML_ASSERT(that->m_size <= that->m_capacity);
    }
    else
    {
        RYML_ASSERT(that->m_capacity <= N);
        RYML_ASSERT(that->m_size <= that->m_capacity);
    }
    memcpy(m_stack, that->m_stack, that->m_size * sizeof(T));
    m_size = that->m_size;
    m_capacity = that->m_size < N ? N : that->m_size;
    m_callbacks = that->m_callbacks;
}


//-----------------------------------------------------------------------------

template<class T, size_t N>
void stack<T, N>::_mv(stack * that)
{
    if(that->m_stack != that->m_buf)
    {
        RYML_ASSERT(that->m_capacity > N);
        RYML_ASSERT(that->m_size <= that->m_capacity);
        m_stack = that->m_stack;
    }
    else
    {
        RYML_ASSERT(that->m_capacity <= N);
        RYML_ASSERT(that->m_size <= that->m_capacity);
        memcpy(m_buf, that->m_buf, that->m_size * sizeof(T));
        m_stack = m_buf;
    }
    m_size = that->m_size;
    m_capacity = that->m_capacity;
    m_callbacks = that->m_callbacks;
    // make sure no deallocation happens on destruction
    RYML_ASSERT(that->m_stack != m_buf);
    that->m_stack = that->m_buf;
    that->m_capacity = N;
    that->m_size = 0;
}


//-----------------------------------------------------------------------------

template<class T, size_t N>
void stack<T, N>::_cb(Callbacks const& cb)
{
    if(cb != m_callbacks)
    {
        _free();
        m_callbacks = cb;
    }
}

} // namespace detail
} // namespace yml
} // namespace c4

#endif /* _C4_YML_DETAIL_STACK_HPP_ */


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/detail/stack.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/parse.hpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/parse.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_YML_PARSE_HPP_
#define _C4_YML_PARSE_HPP_

#ifndef _C4_YML_TREE_HPP_
// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/tree.hpp
//#include "c4/yml/tree.hpp"
#if !defined(C4_YML_TREE_HPP_) && !defined(_C4_YML_TREE_HPP_)
#error "amalgamate: file c4/yml/tree.hpp must have been included at this point"
#endif /* C4_YML_TREE_HPP_ */

#endif

#ifndef _C4_YML_NODE_HPP_
// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/node.hpp
//#include "c4/yml/node.hpp"
#if !defined(C4_YML_NODE_HPP_) && !defined(_C4_YML_NODE_HPP_)
#error "amalgamate: file c4/yml/node.hpp must have been included at this point"
#endif /* C4_YML_NODE_HPP_ */

#endif

#ifndef _C4_YML_DETAIL_STACK_HPP_
// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/detail/stack.hpp
//#include "c4/yml/detail/stack.hpp"
#if !defined(C4_YML_DETAIL_STACK_HPP_) && !defined(_C4_YML_DETAIL_STACK_HPP_)
#error "amalgamate: file c4/yml/detail/stack.hpp must have been included at this point"
#endif /* C4_YML_DETAIL_STACK_HPP_ */

#endif

//included above:
//#include <stdarg.h>

#if defined(_MSC_VER)
#   pragma warning(push)
#   pragma warning(disable: 4251/*needs to have dll-interface to be used by clients of struct*/)
#endif

namespace c4 {
namespace yml {

struct RYML_EXPORT ParserOptions
{
private:

    typedef enum : uint32_t {
        LOCATIONS = (1 << 0),
        DEFAULTS = 0,
    } Flags_e;

    uint32_t flags = DEFAULTS;
public:
    ParserOptions() = default;

    /** @name source location tracking */
    /** @{ */

    /** enable/disable source location tracking */
    ParserOptions& locations(bool enabled)
    {
        if(enabled)
            flags |= LOCATIONS;
        else
            flags &= ~LOCATIONS;
        return *this;
    }
    bool locations() const { return (flags & LOCATIONS) != 0u; }

    /** @} */
};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
class RYML_EXPORT Parser
{
public:

    /** @name construction and assignment */
    /** @{ */

    Parser(Callbacks const& cb, ParserOptions opts={});
    Parser(ParserOptions opts={}) : Parser(get_callbacks(), opts) {}
    ~Parser();

    Parser(Parser &&);
    Parser(Parser const&);
    Parser& operator=(Parser &&);
    Parser& operator=(Parser const&);

    /** @} */

public:

    /** @name modifiers */
    /** @{ */

    /** Reserve a certain capacity for the parsing stack.
     * This should be larger than the expected depth of the parsed
     * YAML tree.
     *
     * The parsing stack is the only (potential) heap memory used by
     * the parser.
     *
     * If the requested capacity is below the default
     * stack size of 16, the memory is used directly in the parser
     * object; otherwise it will be allocated from the heap.
     *
     * @note this reserves memory only for the parser itself; all the
     * allocations for the parsed tree will go through the tree's
     * allocator.
     *
     * @note the tree and the arena can (and should) also be reserved. */
    void reserve_stack(size_t capacity)
    {
        m_stack.reserve(capacity);
    }

    /** Reserve a certain capacity for the array used to track node
     * locations in the source buffer. */
    void reserve_locations(size_t num_source_lines)
    {
        _resize_locations(num_source_lines);
    }

    /** Reserve a certain capacity for the character arena used to
     * filter scalars. */
    void reserve_filter_arena(size_t num_characters)
    {
        _resize_filter_arena(num_characters);
    }

    /** @} */

public:

    /** @name getters and modifiers */
    /** @{ */

    /** Get the current callbacks in the parser. */
    Callbacks callbacks() const { return m_stack.m_callbacks; }

    /** Get the name of the latest file parsed by this object. */
    csubstr filename() const { return m_file; }

    /** Get the latest YAML buffer parsed by this object. */
    csubstr source() const { return m_buf; }

    size_t stack_capacity() const { return m_stack.capacity(); }
    size_t locations_capacity() const { return m_newline_offsets_capacity; }
    size_t filter_arena_capacity() const { return m_filter_arena.len; }

    ParserOptions const& options() const { return m_options; }

    /** @} */

public:

    /** @name parse_in_place */
    /** @{ */

    /** Create a new tree and parse into its root.
     * The tree is created with the callbacks currently in the parser. */
    Tree parse_in_place(csubstr filename, substr src)
    {
        Tree t(callbacks());
        t.reserve(_estimate_capacity(src));
        this->parse_in_place(filename, src, &t, t.root_id());
        return t;
    }

    /** Parse into an existing tree, starting at its root node.
     * The callbacks in the tree are kept, and used to allocate
     * the tree members, if any allocation is required. */
    void parse_in_place(csubstr filename, substr src, Tree *t)
    {
        this->parse_in_place(filename, src, t, t->root_id());
    }

    /** Parse into an existing node.
     * The callbacks in the tree are kept, and used to allocate
     * the tree members, if any allocation is required. */
    void parse_in_place(csubstr filename, substr src, Tree *t, size_t node_id);
    //   ^^^^^^^^^^^^^ this is the workhorse overload; everything else is syntactic candy

    /** Parse into an existing node.
     * The callbacks in the tree are kept, and used to allocate
     * the tree members, if any allocation is required. */
    void parse_in_place(csubstr filename, substr src, NodeRef node)
    {
        this->parse_in_place(filename, src, node.tree(), node.id());
    }

    RYML_DEPRECATED("use parse_in_place() instead") Tree parse(csubstr filename, substr src) { return parse_in_place(filename, src); }
    RYML_DEPRECATED("use parse_in_place() instead") void parse(csubstr filename, substr src, Tree *t) { parse_in_place(filename, src, t); }
    RYML_DEPRECATED("use parse_in_place() instead") void parse(csubstr filename, substr src, Tree *t, size_t node_id) { parse_in_place(filename, src, t, node_id); }
    RYML_DEPRECATED("use parse_in_place() instead") void parse(csubstr filename, substr src, NodeRef node) { parse_in_place(filename, src, node); }

    /** @} */

public:

    /** @name parse_in_arena: copy the YAML source buffer to the
     * tree's arena, then parse the copy in situ
     *
     * @note overloads receiving a substr YAML buffer are intentionally
     * left undefined, such that calling parse_in_arena() with a substr
     * will cause a linker error. This is to prevent an accidental
     * copy of the source buffer to the tree's arena, because substr
     * is implicitly convertible to csubstr. If you really intend to parse
     * a mutable buffer in the tree's arena, convert it first to immutable
     * by assigning the substr to a csubstr prior to calling parse_in_arena().
     * This is not needed for parse_in_place() because csubstr is not
     * implicitly convertible to substr. */
    /** @{ */

    // READ THE NOTE ABOVE!
    #define RYML_DONT_PARSE_SUBSTR_IN_ARENA "Do not pass a (mutable) substr to parse_in_arena(); if you have a substr, it should be parsed in place. Consider using parse_in_place() instead, or convert the buffer to csubstr prior to calling. This function is deliberately left undefined and will cause a linker error."
    RYML_DEPRECATED(RYML_DONT_PARSE_SUBSTR_IN_ARENA) Tree parse_in_arena(csubstr filename, substr csrc);
    RYML_DEPRECATED(RYML_DONT_PARSE_SUBSTR_IN_ARENA) void parse_in_arena(csubstr filename, substr csrc, Tree *t);
    RYML_DEPRECATED(RYML_DONT_PARSE_SUBSTR_IN_ARENA) void parse_in_arena(csubstr filename, substr csrc, Tree *t, size_t node_id);
    RYML_DEPRECATED(RYML_DONT_PARSE_SUBSTR_IN_ARENA) void parse_in_arena(csubstr filename, substr csrc, NodeRef node);

    /** Create a new tree and parse into its root.
     * The immutable YAML source is first copied to the tree's arena,
     * and parsed from there.
     * The callbacks in the tree are kept, and used to allocate
     * the tree members, if any allocation is required. */
    Tree parse_in_arena(csubstr filename, csubstr csrc)
    {
        Tree t(callbacks());
        substr src = t.copy_to_arena(csrc);
        t.reserve(_estimate_capacity(csrc));
        this->parse_in_place(filename, src, &t, t.root_id());
        return t;
    }

    /** Parse into an existing tree, starting at its root node.
     * The immutable YAML source is first copied to the tree's arena,
     * and parsed from there.
     * The callbacks in the tree are kept, and used to allocate
     * the tree members, if any allocation is required. */
    void parse_in_arena(csubstr filename, csubstr csrc, Tree *t)
    {
        substr src = t->copy_to_arena(csrc);
        this->parse_in_place(filename, src, t, t->root_id());
    }

    /** Parse into a specific node in an existing tree.
     * The immutable YAML source is first copied to the tree's arena,
     * and parsed from there.
     * The callbacks in the tree are kept, and used to allocate
     * the tree members, if any allocation is required. */
    void parse_in_arena(csubstr filename, csubstr csrc, Tree *t, size_t node_id)
    {
        substr src = t->copy_to_arena(csrc);
        this->parse_in_place(filename, src, t, node_id);
    }

    /** Parse into a specific node in an existing tree.
     * The immutable YAML source is first copied to the tree's arena,
     * and parsed from there.
     * The callbacks in the tree are kept, and used to allocate
     * the tree members, if any allocation is required. */
    void parse_in_arena(csubstr filename, csubstr csrc, NodeRef node)
    {
        substr src = node.tree()->copy_to_arena(csrc);
        this->parse_in_place(filename, src, node.tree(), node.id());
    }

    RYML_DEPRECATED("use parse_in_arena() instead") Tree parse(csubstr filename, csubstr csrc) { return parse_in_arena(filename, csrc); }
    RYML_DEPRECATED("use parse_in_arena() instead") void parse(csubstr filename, csubstr csrc, Tree *t) { parse_in_arena(filename, csrc, t); }
    RYML_DEPRECATED("use parse_in_arena() instead") void parse(csubstr filename, csubstr csrc, Tree *t, size_t node_id) { parse_in_arena(filename, csrc, t, node_id); }
    RYML_DEPRECATED("use parse_in_arena() instead") void parse(csubstr filename, csubstr csrc, NodeRef node) { parse_in_arena(filename, csrc, node); }

    /** @} */

public:

    /** @name locations */
    /** @{ */

    /** Get the location of a node of the last tree to be parsed by this parser. */
    Location location(Tree const& tree, size_t node_id) const;
    /** Get the location of a node of the last tree to be parsed by this parser. */
    Location location(ConstNodeRef node) const;
    /** Get the string starting at a particular location, to the end
     * of the parsed source buffer. */
    csubstr location_contents(Location const& loc) const;
    /** Given a pointer to a buffer position, get the location. @p val
     * must be pointing to somewhere in the source buffer that was
     * last parsed by this object. */
    Location val_location(const char *val) const;

    /** @} */

private:

    typedef enum {
        BLOCK_LITERAL, //!< keep newlines (|)
        BLOCK_FOLD     //!< replace newline with single space (>)
    } BlockStyle_e;

    typedef enum {
        CHOMP_CLIP,    //!< single newline at end (default)
        CHOMP_STRIP,   //!< no newline at end     (-)
        CHOMP_KEEP     //!< all newlines from end (+)
    } BlockChomp_e;

private:

    using flag_t = int;

    static size_t _estimate_capacity(csubstr src) { size_t c = _count_nlines(src); c = c >= 16 ? c : 16; return c; }

    void  _reset();

    bool  _finished_file() const;
    bool  _finished_line() const;

    csubstr _peek_next_line(size_t pos=npos) const;
    bool    _advance_to_peeked();
    void    _scan_line();

    csubstr _slurp_doc_scalar();

    /**
     * @param [out] quoted
     * Will only be written to if this method returns true.
     * Will be set to true if the scanned scalar was quoted, by '', "", > or |.
     */
    bool    _scan_scalar_seq_blck(csubstr *C4_RESTRICT scalar, bool *C4_RESTRICT quoted);
    bool    _scan_scalar_map_blck(csubstr *C4_RESTRICT scalar, bool *C4_RESTRICT quoted);
    bool    _scan_scalar_seq_flow(csubstr *C4_RESTRICT scalar, bool *C4_RESTRICT quoted);
    bool    _scan_scalar_map_flow(csubstr *C4_RESTRICT scalar, bool *C4_RESTRICT quoted);
    bool    _scan_scalar_unk(csubstr *C4_RESTRICT scalar, bool *C4_RESTRICT quoted);

    csubstr _scan_comment();
    csubstr _scan_squot_scalar();
    csubstr _scan_dquot_scalar();
    csubstr _scan_block();
    substr  _scan_plain_scalar_blck(csubstr currscalar, csubstr peeked_line, size_t indentation);
    substr  _scan_plain_scalar_flow(csubstr currscalar, csubstr peeked_line);
    substr  _scan_complex_key(csubstr currscalar, csubstr peeked_line);
    csubstr _scan_to_next_nonempty_line(size_t indentation);
    csubstr _extend_scanned_scalar(csubstr currscalar);

    csubstr _filter_squot_scalar(const substr s);
    csubstr _filter_dquot_scalar(substr s);
    csubstr _filter_plain_scalar(substr s, size_t indentation);
    csubstr _filter_block_scalar(substr s, BlockStyle_e style, BlockChomp_e chomp, size_t indentation);
    template<bool backslash_is_escape, bool keep_trailing_whitespace>
    bool    _filter_nl(substr scalar, size_t *C4_RESTRICT pos, size_t *C4_RESTRICT filter_arena_pos, size_t indentation);
    template<bool keep_trailing_whitespace>
    void    _filter_ws(substr scalar, size_t *C4_RESTRICT pos, size_t *C4_RESTRICT filter_arena_pos);
    bool    _apply_chomp(substr buf, size_t *C4_RESTRICT pos, BlockChomp_e chomp);

    void  _handle_finished_file();
    void  _handle_line();

    bool  _handle_indentation();

    bool  _handle_unk();
    bool  _handle_map_flow();
    bool  _handle_map_blck();
    bool  _handle_seq_flow();
    bool  _handle_seq_blck();
    bool  _handle_top();
    bool  _handle_types();
    bool  _handle_key_anchors_and_refs();
    bool  _handle_val_anchors_and_refs();
    void  _move_val_tag_to_key_tag();
    void  _move_key_tag_to_val_tag();
    void  _move_key_tag2_to_key_tag();
    void  _move_val_anchor_to_key_anchor();
    void  _move_key_anchor_to_val_anchor();

    void  _push_level(bool explicit_flow_chars = false);
    void  _pop_level();

    void  _start_unk(bool as_child=true);

    void  _start_map(bool as_child=true);
    void  _start_map_unk(bool as_child);
    void  _stop_map();

    void  _start_seq(bool as_child=true);
    void  _stop_seq();

    void  _start_seqimap();
    void  _stop_seqimap();

    void  _start_doc(bool as_child=true);
    void  _stop_doc();
    void  _start_new_doc(csubstr rem);
    void  _end_stream();

    NodeData* _append_val(csubstr val, flag_t quoted=false);
    NodeData* _append_key_val(csubstr val, flag_t val_quoted=false);
    bool  _rval_dash_start_or_continue_seq();

    void  _store_scalar(csubstr s, flag_t is_quoted);
    csubstr _consume_scalar();
    void  _move_scalar_from_top();

    inline NodeData* _append_val_null(const char *str) { _RYML_CB_ASSERT(m_stack.m_callbacks, str >= m_buf.begin() && str <= m_buf.end()); return _append_val({nullptr, size_t(0)}); }
    inline NodeData* _append_key_val_null(const char *str) { _RYML_CB_ASSERT(m_stack.m_callbacks, str >= m_buf.begin() && str <= m_buf.end()); return _append_key_val({nullptr, size_t(0)}); }
    inline void      _store_scalar_null(const char *str) {  _RYML_CB_ASSERT(m_stack.m_callbacks, str >= m_buf.begin() && str <= m_buf.end()); _store_scalar({nullptr, size_t(0)}, false); }

    void  _set_indentation(size_t behind);
    void  _save_indentation(size_t behind=0);
    bool  _maybe_set_indentation_from_anchor_or_tag();

    void  _write_key_anchor(size_t node_id);
    void  _write_val_anchor(size_t node_id);

    void _handle_directive(csubstr directive);

    void _skipchars(char c);
    template<size_t N>
    void _skipchars(const char (&chars)[N]);

private:

    static size_t _count_nlines(csubstr src);

private:

    typedef enum : flag_t {
        RTOP = 0x01 <<  0,   ///< reading at top level
        RUNK = 0x01 <<  1,   ///< reading an unknown: must determine whether scalar, map or seq
        RMAP = 0x01 <<  2,   ///< reading a map
        RSEQ = 0x01 <<  3,   ///< reading a seq
        FLOW = 0x01 <<  4,   ///< reading is inside explicit flow chars: [] or {}
        QMRK = 0x01 <<  5,   ///< reading an explicit key (`? key`)
        RKEY = 0x01 <<  6,   ///< reading a scalar as key
        RVAL = 0x01 <<  7,   ///< reading a scalar as val
        RNXT = 0x01 <<  8,   ///< read next val or keyval
        SSCL = 0x01 <<  9,   ///< there's a stored scalar
        QSCL = 0x01 << 10,   ///< stored scalar was quoted
        RSET = 0x01 << 11,   ///< the (implicit) map being read is a !!set. @see https://yaml.org/type/set.html
        NDOC = 0x01 << 12,   ///< no document mode. a document has ended and another has not started yet.
        //! reading an implicit map nested in an explicit seq.
        //! eg, {key: [key2: value2, key3: value3]}
        //! is parsed as {key: [{key2: value2}, {key3: value3}]}
        RSEQIMAP = 0x01 << 13,
    } State_e;

    struct LineContents
    {
        csubstr  full;        ///< the full line, including newlines on the right
        csubstr  stripped;    ///< the stripped line, excluding newlines on the right
        csubstr  rem;         ///< the stripped line remainder; initially starts at the first non-space character
        size_t   indentation; ///< the number of spaces on the beginning of the line

        LineContents() : full(), stripped(), rem(), indentation() {}

        void reset_with_next_line(csubstr buf, size_t pos);

        void reset(csubstr full_, csubstr stripped_)
        {
            full = full_;
            stripped = stripped_;
            rem = stripped_;
            // find the first column where the character is not a space
            indentation = full.first_not_of(' ');
        }

        size_t current_col() const
        {
            return current_col(rem);
        }

        size_t current_col(csubstr s) const
        {
            RYML_ASSERT(s.str >= full.str);
            RYML_ASSERT(full.is_super(s));
            size_t col = static_cast<size_t>(s.str - full.str);
            return col;
        }
    };

    struct State
    {
        flag_t       flags;
        size_t       level;
        size_t       node_id; // don't hold a pointer to the node as it will be relocated during tree resizes
        csubstr      scalar;
        size_t       scalar_col; // the column where the scalar (or its quotes) begin

        Location     pos;
        LineContents line_contents;
        size_t       indref;

        State() : flags(), level(), node_id(), scalar(), scalar_col(), pos(), line_contents(), indref() {}

        void reset(const char *file, size_t node_id_)
        {
            flags = RUNK|RTOP;
            level = 0;
            pos.name = to_csubstr(file);
            pos.offset = 0;
            pos.line = 1;
            pos.col = 1;
            node_id = node_id_;
            scalar_col = 0;
            scalar.clear();
            indref = 0;
        }
    };

    void _line_progressed(size_t ahead);
    void _line_ended();
    void _line_ended_undo();

    void _prepare_pop()
    {
        RYML_ASSERT(m_stack.size() > 1);
        State const& curr = m_stack.top();
        State      & next = m_stack.top(1);
        next.pos = curr.pos;
        next.line_contents = curr.line_contents;
        next.scalar = curr.scalar;
    }

    inline bool _at_line_begin() const
    {
        return m_state->line_contents.rem.begin() == m_state->line_contents.full.begin();
    }
    inline bool _at_line_end() const
    {
        csubstr r = m_state->line_contents.rem;
        return r.empty() || r.begins_with(' ', r.len);
    }
    inline bool _token_is_from_this_line(csubstr token) const
    {
        return token.is_sub(m_state->line_contents.full);
    }

    inline NodeData * node(State const* s) const { return m_tree->get(s->node_id); }
    inline NodeData * node(State const& s) const { return m_tree->get(s .node_id); }
    inline NodeData * node(size_t node_id) const { return m_tree->get(   node_id); }

    inline bool has_all(flag_t f) const { return (m_state->flags & f) == f; }
    inline bool has_any(flag_t f) const { return (m_state->flags & f) != 0; }
    inline bool has_none(flag_t f) const { return (m_state->flags & f) == 0; }

    static inline bool has_all(flag_t f, State const* s) { return (s->flags & f) == f; }
    static inline bool has_any(flag_t f, State const* s) { return (s->flags & f) != 0; }
    static inline bool has_none(flag_t f, State const* s) { return (s->flags & f) == 0; }

    inline void set_flags(flag_t f) { set_flags(f, m_state); }
    inline void add_flags(flag_t on) { add_flags(on, m_state); }
    inline void addrem_flags(flag_t on, flag_t off) { addrem_flags(on, off, m_state); }
    inline void rem_flags(flag_t off) { rem_flags(off, m_state); }

    void set_flags(flag_t f, State * s);
    void add_flags(flag_t on, State * s);
    void addrem_flags(flag_t on, flag_t off, State * s);
    void rem_flags(flag_t off, State * s);

    void _resize_filter_arena(size_t num_characters);
    void _grow_filter_arena(size_t num_characters);
    substr _finish_filter_arena(substr dst, size_t pos);

    void _prepare_locations();
    void _resize_locations(size_t sz);
    bool _locations_dirty() const;

    bool _location_from_cont(Tree const& tree, size_t node, Location *C4_RESTRICT loc) const;
    bool _location_from_node(Tree const& tree, size_t node, Location *C4_RESTRICT loc, size_t level) const;

private:

    void _free();
    void _clr();
    void _cp(Parser const* that);
    void _mv(Parser *that);

#ifdef RYML_DBG
    template<class ...Args> void _dbg(csubstr fmt, Args const& C4_RESTRICT ...args) const;
#endif
    template<class ...Args> void _err(csubstr fmt, Args const& C4_RESTRICT ...args) const;
    template<class DumpFn>  void _fmt_msg(DumpFn &&dumpfn) const;
    static csubstr _prfl(substr buf, flag_t v);

private:

    ParserOptions m_options;

    csubstr m_file;
     substr m_buf;

    size_t  m_root_id;
    Tree *  m_tree;

    detail::stack<State> m_stack;
    State * m_state;

    size_t  m_key_tag_indentation;
    size_t  m_key_tag2_indentation;
    csubstr m_key_tag;
    csubstr m_key_tag2;
    size_t  m_val_tag_indentation;
    csubstr m_val_tag;

    bool    m_key_anchor_was_before;
    size_t  m_key_anchor_indentation;
    csubstr m_key_anchor;
    size_t  m_val_anchor_indentation;
    csubstr m_val_anchor;

    substr m_filter_arena;

    size_t *m_newline_offsets;
    size_t  m_newline_offsets_size;
    size_t  m_newline_offsets_capacity;
    csubstr m_newline_offsets_buf;
};


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

/** @name parse_in_place
 *
 * @desc parse a mutable YAML source buffer.
 *
 * @note These freestanding functions use a temporary parser object,
 * and are convenience functions to easily parse YAML without the need
 * to instantiate a separate parser. Note that some properties
 * (notably node locations in the original source code) are only
 * available through the parser object after it has parsed the
 * code. If you need access to any of these properties, use
 * Parser::parse_in_place() */
/** @{ */

inline Tree parse_in_place(                  substr yaml                         ) { Parser np; return np.parse_in_place({}      , yaml); } //!< parse in-situ a modifiable YAML source buffer.
inline Tree parse_in_place(csubstr filename, substr yaml                         ) { Parser np; return np.parse_in_place(filename, yaml); } //!< parse in-situ a modifiable YAML source buffer, providing a filename for error messages.
inline void parse_in_place(                  substr yaml, Tree *t                ) { Parser np; np.parse_in_place({}      , yaml, t); } //!< reusing the YAML tree, parse in-situ a modifiable YAML source buffer
inline void parse_in_place(csubstr filename, substr yaml, Tree *t                ) { Parser np; np.parse_in_place(filename, yaml, t); } //!< reusing the YAML tree, parse in-situ a modifiable YAML source buffer, providing a filename for error messages.
inline void parse_in_place(                  substr yaml, Tree *t, size_t node_id) { Parser np; np.parse_in_place({}      , yaml, t, node_id); } //!< reusing the YAML tree, parse in-situ a modifiable YAML source buffer
inline void parse_in_place(csubstr filename, substr yaml, Tree *t, size_t node_id) { Parser np; np.parse_in_place(filename, yaml, t, node_id); } //!< reusing the YAML tree, parse in-situ a modifiable YAML source buffer, providing a filename for error messages.
inline void parse_in_place(                  substr yaml, NodeRef node           ) { Parser np; np.parse_in_place({}      , yaml, node); } //!< reusing the YAML tree, parse in-situ a modifiable YAML source buffer
inline void parse_in_place(csubstr filename, substr yaml, NodeRef node           ) { Parser np; np.parse_in_place(filename, yaml, node); } //!< reusing the YAML tree, parse in-situ a modifiable YAML source buffer, providing a filename for error messages.

RYML_DEPRECATED("use parse_in_place() instead") inline Tree parse(                  substr yaml                         ) { Parser np; return np.parse_in_place({}      , yaml); }
RYML_DEPRECATED("use parse_in_place() instead") inline Tree parse(csubstr filename, substr yaml                         ) { Parser np; return np.parse_in_place(filename, yaml); }
RYML_DEPRECATED("use parse_in_place() instead") inline void parse(                  substr yaml, Tree *t                ) { Parser np; np.parse_in_place({}      , yaml, t); }
RYML_DEPRECATED("use parse_in_place() instead") inline void parse(csubstr filename, substr yaml, Tree *t                ) { Parser np; np.parse_in_place(filename, yaml, t); }
RYML_DEPRECATED("use parse_in_place() instead") inline void parse(                  substr yaml, Tree *t, size_t node_id) { Parser np; np.parse_in_place({}      , yaml, t, node_id); }
RYML_DEPRECATED("use parse_in_place() instead") inline void parse(csubstr filename, substr yaml, Tree *t, size_t node_id) { Parser np; np.parse_in_place(filename, yaml, t, node_id); }
RYML_DEPRECATED("use parse_in_place() instead") inline void parse(                  substr yaml, NodeRef node           ) { Parser np; np.parse_in_place({}      , yaml, node); }
RYML_DEPRECATED("use parse_in_place() instead") inline void parse(csubstr filename, substr yaml, NodeRef node           ) { Parser np; np.parse_in_place(filename, yaml, node); }

/** @} */


//-----------------------------------------------------------------------------

/** @name parse_in_arena
 * @desc parse a read-only YAML source buffer, copying it first to the tree's arena.
 *
 * @note These freestanding functions use a temporary parser object,
 * and are convenience functions to easily parse YAML without the need
 * to instantiate a separate parser. Note that some properties
 * (notably node locations in the original source code) are only
 * available through the parser object after it has parsed the
 * code. If you need access to any of these properties, use
 * Parser::parse_in_arena().
 *
 * @note overloads receiving a substr YAML buffer are intentionally
 * left undefined, such that calling parse_in_arena() with a substr
 * will cause a linker error. This is to prevent an accidental
 * copy of the source buffer to the tree's arena, because substr
 * is implicitly convertible to csubstr. If you really intend to parse
 * a mutable buffer in the tree's arena, convert it first to immutable
 * by assigning the substr to a csubstr prior to calling parse_in_arena().
 * This is not needed for parse_in_place() because csubstr is not
 * implicitly convertible to substr. */
/** @{ */

/* READ THE NOTE ABOVE! */
RYML_DEPRECATED(RYML_DONT_PARSE_SUBSTR_IN_ARENA) Tree parse_in_arena(                  substr yaml                         );
RYML_DEPRECATED(RYML_DONT_PARSE_SUBSTR_IN_ARENA) Tree parse_in_arena(csubstr filename, substr yaml                         );
RYML_DEPRECATED(RYML_DONT_PARSE_SUBSTR_IN_ARENA) void parse_in_arena(                  substr yaml, Tree *t                );
RYML_DEPRECATED(RYML_DONT_PARSE_SUBSTR_IN_ARENA) void parse_in_arena(csubstr filename, substr yaml, Tree *t                );
RYML_DEPRECATED(RYML_DONT_PARSE_SUBSTR_IN_ARENA) void parse_in_arena(                  substr yaml, Tree *t, size_t node_id);
RYML_DEPRECATED(RYML_DONT_PARSE_SUBSTR_IN_ARENA) void parse_in_arena(csubstr filename, substr yaml, Tree *t, size_t node_id);
RYML_DEPRECATED(RYML_DONT_PARSE_SUBSTR_IN_ARENA) void parse_in_arena(                  substr yaml, NodeRef node           );
RYML_DEPRECATED(RYML_DONT_PARSE_SUBSTR_IN_ARENA) void parse_in_arena(csubstr filename, substr yaml, NodeRef node           );

inline Tree parse_in_arena(                  csubstr yaml                         ) { Parser np; return np.parse_in_arena({}      , yaml); } //!< parse a read-only YAML source buffer, copying it first to the tree's source arena.
inline Tree parse_in_arena(csubstr filename, csubstr yaml                         ) { Parser np; return np.parse_in_arena(filename, yaml); } //!< parse a read-only YAML source buffer, copying it first to the tree's source arena, providing a filename for error messages.
inline void parse_in_arena(                  csubstr yaml, Tree *t                ) { Parser np; np.parse_in_arena({}      , yaml, t); } //!< reusing the YAML tree, parse a read-only YAML source buffer, copying it first to the tree's source arena.
inline void parse_in_arena(csubstr filename, csubstr yaml, Tree *t                ) { Parser np; np.parse_in_arena(filename, yaml, t); } //!< reusing the YAML tree, parse a read-only YAML source buffer, copying it first to the tree's source arena, providing a filename for error messages.
inline void parse_in_arena(                  csubstr yaml, Tree *t, size_t node_id) { Parser np; np.parse_in_arena({}      , yaml, t, node_id); } //!< reusing the YAML tree, parse a read-only YAML source buffer, copying it first to the tree's source arena.
inline void parse_in_arena(csubstr filename, csubstr yaml, Tree *t, size_t node_id) { Parser np; np.parse_in_arena(filename, yaml, t, node_id); } //!< reusing the YAML tree, parse a read-only YAML source buffer, copying it first to the tree's source arena, providing a filename for error messages.
inline void parse_in_arena(                  csubstr yaml, NodeRef node           ) { Parser np; np.parse_in_arena({}      , yaml, node); } //!< reusing the YAML tree, parse a read-only YAML source buffer, copying it first to the tree's source arena.
inline void parse_in_arena(csubstr filename, csubstr yaml, NodeRef node           ) { Parser np; np.parse_in_arena(filename, yaml, node); } //!< reusing the YAML tree, parse a read-only YAML source buffer, copying it first to the tree's source arena, providing a filename for error messages.

RYML_DEPRECATED("use parse_in_arena() instead") inline Tree parse(                  csubstr yaml                         ) { Parser np; return np.parse_in_arena({}      , yaml); } //!< parse a read-only YAML source buffer, copying it first to the tree's source arena.
RYML_DEPRECATED("use parse_in_arena() instead") inline Tree parse(csubstr filename, csubstr yaml                         ) { Parser np; return np.parse_in_arena(filename, yaml); } //!< parse a read-only YAML source buffer, copying it first to the tree's source arena, providing a filename for error messages.
RYML_DEPRECATED("use parse_in_arena() instead") inline void parse(                  csubstr yaml, Tree *t                ) { Parser np; np.parse_in_arena({}      , yaml, t); } //!< reusing the YAML tree, parse a read-only YAML source buffer, copying it first to the tree's source arena.
RYML_DEPRECATED("use parse_in_arena() instead") inline void parse(csubstr filename, csubstr yaml, Tree *t                ) { Parser np; np.parse_in_arena(filename, yaml, t); } //!< reusing the YAML tree, parse a read-only YAML source buffer, copying it first to the tree's source arena, providing a filename for error messages.
RYML_DEPRECATED("use parse_in_arena() instead") inline void parse(                  csubstr yaml, Tree *t, size_t node_id) { Parser np; np.parse_in_arena({}      , yaml, t, node_id); } //!< reusing the YAML tree, parse a read-only YAML source buffer, copying it first to the tree's source arena.
RYML_DEPRECATED("use parse_in_arena() instead") inline void parse(csubstr filename, csubstr yaml, Tree *t, size_t node_id) { Parser np; np.parse_in_arena(filename, yaml, t, node_id); } //!< reusing the YAML tree, parse a read-only YAML source buffer, copying it first to the tree's source arena, providing a filename for error messages.
RYML_DEPRECATED("use parse_in_arena() instead") inline void parse(                  csubstr yaml, NodeRef node           ) { Parser np; np.parse_in_arena({}      , yaml, node); } //!< reusing the YAML tree, parse a read-only YAML source buffer, copying it first to the tree's source arena.
RYML_DEPRECATED("use parse_in_arena() instead") inline void parse(csubstr filename, csubstr yaml, NodeRef node           ) { Parser np; np.parse_in_arena(filename, yaml, node); } //!< reusing the YAML tree, parse a read-only YAML source buffer, copying it first to the tree's source arena, providing a filename for error messages.

/** @} */

} // namespace yml
} // namespace c4

#if defined(_MSC_VER)
#   pragma warning(pop)
#endif

#endif /* _C4_YML_PARSE_HPP_ */


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/parse.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/std/map.hpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/std/map.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_YML_STD_MAP_HPP_
#define _C4_YML_STD_MAP_HPP_

/** @file map.hpp write/read std::map to/from a YAML tree. */

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/node.hpp
//#include "c4/yml/node.hpp"
#if !defined(C4_YML_NODE_HPP_) && !defined(_C4_YML_NODE_HPP_)
#error "amalgamate: file c4/yml/node.hpp must have been included at this point"
#endif /* C4_YML_NODE_HPP_ */

#include <map>

namespace c4 {
namespace yml {

// std::map requires child nodes in the data
// tree hierarchy (a MAP node in ryml parlance).
// So it should be serialized via write()/read().

template<class K, class V, class Less, class Alloc>
void write(c4::yml::NodeRef *n, std::map<K, V, Less, Alloc> const& m)
{
    *n |= c4::yml::MAP;
    for(auto const& C4_RESTRICT p : m)
    {
        auto ch = n->append_child();
        ch << c4::yml::key(p.first);
        ch << p.second;
    }
}

template<class K, class V, class Less, class Alloc>
bool read(c4::yml::ConstNodeRef const& n, std::map<K, V, Less, Alloc> * m)
{
    K k{};
    V v{};
    for(auto const& C4_RESTRICT ch : n)
    {
        ch >> c4::yml::key(k);
        ch >> v;
        m->emplace(std::make_pair(std::move(k), std::move(v)));
    }
    return true;
}

} // namespace yml
} // namespace c4

#endif // _C4_YML_STD_MAP_HPP_


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/std/map.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/std/string.hpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/std/string.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef C4_YML_STD_STRING_HPP_
#define C4_YML_STD_STRING_HPP_

/** @file string.hpp substring conversions for/from std::string */

// everything we need is implemented here:
// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/std/string.hpp
//#include <c4/std/string.hpp>
#if !defined(C4_STD_STRING_HPP_) && !defined(_C4_STD_STRING_HPP_)
#error "amalgamate: file c4/std/string.hpp must have been included at this point"
#endif /* C4_STD_STRING_HPP_ */


#endif // C4_YML_STD_STRING_HPP_


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/std/string.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/std/vector.hpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/std/vector.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_YML_STD_VECTOR_HPP_
#define _C4_YML_STD_VECTOR_HPP_

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/node.hpp
//#include "c4/yml/node.hpp"
#if !defined(C4_YML_NODE_HPP_) && !defined(_C4_YML_NODE_HPP_)
#error "amalgamate: file c4/yml/node.hpp must have been included at this point"
#endif /* C4_YML_NODE_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/std/vector.hpp
//#include <c4/std/vector.hpp>
#if !defined(C4_STD_VECTOR_HPP_) && !defined(_C4_STD_VECTOR_HPP_)
#error "amalgamate: file c4/std/vector.hpp must have been included at this point"
#endif /* C4_STD_VECTOR_HPP_ */

//included above:
//#include <vector>

namespace c4 {
namespace yml {

// vector is a sequence-like type, and it requires child nodes
// in the data tree hierarchy (a SEQ node in ryml parlance).
// So it should be serialized via write()/read().


template<class V, class Alloc>
void write(c4::yml::NodeRef *n, std::vector<V, Alloc> const& vec)
{
    *n |= c4::yml::SEQ;
    for(auto const& v : vec)
        n->append_child() << v;
}

template<class V, class Alloc>
bool read(c4::yml::ConstNodeRef const& n, std::vector<V, Alloc> *vec)
{
    vec->resize(n.num_children());
    size_t pos = 0;
    for(auto const ch : n)
        ch >> (*vec)[pos++];
    return true;
}

/** specialization: std::vector<bool> uses std::vector<bool>::reference as
 * the return value of its operator[]. */
template<class Alloc>
bool read(c4::yml::ConstNodeRef const& n, std::vector<bool, Alloc> *vec)
{
    vec->resize(n.num_children());
    size_t pos = 0;
    bool tmp;
    for(auto const ch : n)
    {
        ch >> tmp;
        (*vec)[pos++] = tmp;
    }
    return true;
}

} // namespace yml
} // namespace c4

#endif // _C4_YML_STD_VECTOR_HPP_


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/std/vector.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/std/std.hpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/std/std.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_YML_STD_STD_HPP_
#define _C4_YML_STD_STD_HPP_

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/std/string.hpp
//#include "c4/yml/std/string.hpp"
#if !defined(C4_YML_STD_STRING_HPP_) && !defined(_C4_YML_STD_STRING_HPP_)
#error "amalgamate: file c4/yml/std/string.hpp must have been included at this point"
#endif /* C4_YML_STD_STRING_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/std/vector.hpp
//#include "c4/yml/std/vector.hpp"
#if !defined(C4_YML_STD_VECTOR_HPP_) && !defined(_C4_YML_STD_VECTOR_HPP_)
#error "amalgamate: file c4/yml/std/vector.hpp must have been included at this point"
#endif /* C4_YML_STD_VECTOR_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/std/map.hpp
//#include "c4/yml/std/map.hpp"
#if !defined(C4_YML_STD_MAP_HPP_) && !defined(_C4_YML_STD_MAP_HPP_)
#error "amalgamate: file c4/yml/std/map.hpp must have been included at this point"
#endif /* C4_YML_STD_MAP_HPP_ */


#endif // _C4_YML_STD_STD_HPP_


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/std/std.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/common.cpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/common.cpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifdef RYML_SINGLE_HDR_DEFINE_NOW
// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/common.hpp
//#include "c4/yml/common.hpp"
#if !defined(C4_YML_COMMON_HPP_) && !defined(_C4_YML_COMMON_HPP_)
#error "amalgamate: file c4/yml/common.hpp must have been included at this point"
#endif /* C4_YML_COMMON_HPP_ */


#ifndef RYML_NO_DEFAULT_CALLBACKS
//included above:
//#   include <stdlib.h>
//included above:
//#   include <stdio.h>
#endif // RYML_NO_DEFAULT_CALLBACKS

namespace c4 {
namespace yml {

namespace {
Callbacks s_default_callbacks;
} // anon namespace

#ifndef RYML_NO_DEFAULT_CALLBACKS
void report_error_impl(const char* msg, size_t length, Location loc, FILE *f)
{
    if(!f)
        f = stderr;
    if(loc)
    {
        if(!loc.name.empty())
        {
            fwrite(loc.name.str, 1, loc.name.len, f);
            fputc(':', f);
        }
        fprintf(f, "%zu:", loc.line);
        if(loc.col)
            fprintf(f, "%zu:", loc.col);
        if(loc.offset)
            fprintf(f, " (%zuB):", loc.offset);
    }
    fprintf(f, "%.*s\n", (int)length, msg);
    fflush(f);
}

void error_impl(const char* msg, size_t length, Location loc, void * /*user_data*/)
{
    report_error_impl(msg, length, loc, nullptr);
    ::abort();
}

void* allocate_impl(size_t length, void * /*hint*/, void * /*user_data*/)
{
    void *mem = ::malloc(length);
    if(mem == nullptr)
    {
        const char msg[] = "could not allocate memory";
        error_impl(msg, sizeof(msg)-1, {}, nullptr);
    }
    return mem;
}

void free_impl(void *mem, size_t /*length*/, void * /*user_data*/)
{
    ::free(mem);
}
#endif // RYML_NO_DEFAULT_CALLBACKS



Callbacks::Callbacks()
    :
    m_user_data(nullptr),
    #ifndef RYML_NO_DEFAULT_CALLBACKS
    m_allocate(allocate_impl),
    m_free(free_impl),
    m_error(error_impl)
    #else
    m_allocate(nullptr),
    m_free(nullptr),
    m_error(nullptr)
    #endif
{
}

Callbacks::Callbacks(void *user_data, pfn_allocate alloc_, pfn_free free_, pfn_error error_)
    :
    m_user_data(user_data),
    #ifndef RYML_NO_DEFAULT_CALLBACKS
    m_allocate(alloc_ ? alloc_ : allocate_impl),
    m_free(free_ ? free_ : free_impl),
    m_error(error_ ? error_ : error_impl)
    #else
    m_allocate(alloc_),
    m_free(free_),
    m_error(error_)
    #endif
{
    C4_CHECK(m_allocate);
    C4_CHECK(m_free);
    C4_CHECK(m_error);
}


void set_callbacks(Callbacks const& c)
{
    s_default_callbacks = c;
}

Callbacks const& get_callbacks()
{
    return s_default_callbacks;
}

void reset_callbacks()
{
    set_callbacks(Callbacks());
}

void error(const char *msg, size_t msg_len, Location loc)
{
    s_default_callbacks.m_error(msg, msg_len, loc, s_default_callbacks.m_user_data);
}

} // namespace yml
} // namespace c4

#endif /* RYML_SINGLE_HDR_DEFINE_NOW */


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/common.cpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/tree.cpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/tree.cpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifdef RYML_SINGLE_HDR_DEFINE_NOW
// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/tree.hpp
//#include "c4/yml/tree.hpp"
#if !defined(C4_YML_TREE_HPP_) && !defined(_C4_YML_TREE_HPP_)
#error "amalgamate: file c4/yml/tree.hpp must have been included at this point"
#endif /* C4_YML_TREE_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/detail/parser_dbg.hpp
//#include "c4/yml/detail/parser_dbg.hpp"
#if !defined(C4_YML_DETAIL_PARSER_DBG_HPP_) && !defined(_C4_YML_DETAIL_PARSER_DBG_HPP_)
#error "amalgamate: file c4/yml/detail/parser_dbg.hpp must have been included at this point"
#endif /* C4_YML_DETAIL_PARSER_DBG_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/node.hpp
//#include "c4/yml/node.hpp"
#if !defined(C4_YML_NODE_HPP_) && !defined(_C4_YML_NODE_HPP_)
#error "amalgamate: file c4/yml/node.hpp must have been included at this point"
#endif /* C4_YML_NODE_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/detail/stack.hpp
//#include "c4/yml/detail/stack.hpp"
#if !defined(C4_YML_DETAIL_STACK_HPP_) && !defined(_C4_YML_DETAIL_STACK_HPP_)
#error "amalgamate: file c4/yml/detail/stack.hpp must have been included at this point"
#endif /* C4_YML_DETAIL_STACK_HPP_ */



C4_SUPPRESS_WARNING_GCC_WITH_PUSH("-Wtype-limits")
C4_SUPPRESS_WARNING_MSVC_WITH_PUSH(4296/*expression is always 'boolean_value'*/)

namespace c4 {
namespace yml {


csubstr normalize_tag(csubstr tag)
{
    YamlTag_e t = to_tag(tag);
    if(t != TAG_NONE)
        return from_tag(t);
    if(tag.begins_with("!<"))
        tag = tag.sub(1);
    if(tag.begins_with("<!"))
        return tag;
    return tag;
}

csubstr normalize_tag_long(csubstr tag)
{
    YamlTag_e t = to_tag(tag);
    if(t != TAG_NONE)
        return from_tag_long(t);
    if(tag.begins_with("!<"))
        tag = tag.sub(1);
    if(tag.begins_with("<!"))
        return tag;
    return tag;
}

YamlTag_e to_tag(csubstr tag)
{
    if(tag.begins_with("!<"))
        tag = tag.sub(1);
    if(tag.begins_with("!!"))
        tag = tag.sub(2);
    else if(tag.begins_with('!'))
        return TAG_NONE;
    else if(tag.begins_with("tag:yaml.org,2002:"))
    {
        RYML_ASSERT(csubstr("tag:yaml.org,2002:").len == 18);
        tag = tag.sub(18);
    }
    else if(tag.begins_with("<tag:yaml.org,2002:"))
    {
        RYML_ASSERT(csubstr("<tag:yaml.org,2002:").len == 19);
        tag = tag.sub(19);
        if(!tag.len)
            return TAG_NONE;
        tag = tag.offs(0, 1);
    }

    if(tag == "map")
        return TAG_MAP;
    else if(tag == "omap")
        return TAG_OMAP;
    else if(tag == "pairs")
        return TAG_PAIRS;
    else if(tag == "set")
        return TAG_SET;
    else if(tag == "seq")
        return TAG_SEQ;
    else if(tag == "binary")
        return TAG_BINARY;
    else if(tag == "bool")
        return TAG_BOOL;
    else if(tag == "float")
        return TAG_FLOAT;
    else if(tag == "int")
        return TAG_INT;
    else if(tag == "merge")
        return TAG_MERGE;
    else if(tag == "null")
        return TAG_NULL;
    else if(tag == "str")
        return TAG_STR;
    else if(tag == "timestamp")
        return TAG_TIMESTAMP;
    else if(tag == "value")
        return TAG_VALUE;

    return TAG_NONE;
}

csubstr from_tag_long(YamlTag_e tag)
{
    switch(tag)
    {
    case TAG_MAP:
        return {"<tag:yaml.org,2002:map>"};
    case TAG_OMAP:
        return {"<tag:yaml.org,2002:omap>"};
    case TAG_PAIRS:
        return {"<tag:yaml.org,2002:pairs>"};
    case TAG_SET:
        return {"<tag:yaml.org,2002:set>"};
    case TAG_SEQ:
        return {"<tag:yaml.org,2002:seq>"};
    case TAG_BINARY:
        return {"<tag:yaml.org,2002:binary>"};
    case TAG_BOOL:
        return {"<tag:yaml.org,2002:bool>"};
    case TAG_FLOAT:
        return {"<tag:yaml.org,2002:float>"};
    case TAG_INT:
        return {"<tag:yaml.org,2002:int>"};
    case TAG_MERGE:
        return {"<tag:yaml.org,2002:merge>"};
    case TAG_NULL:
        return {"<tag:yaml.org,2002:null>"};
    case TAG_STR:
        return {"<tag:yaml.org,2002:str>"};
    case TAG_TIMESTAMP:
        return {"<tag:yaml.org,2002:timestamp>"};
    case TAG_VALUE:
        return {"<tag:yaml.org,2002:value>"};
    case TAG_YAML:
        return {"<tag:yaml.org,2002:yaml>"};
    case TAG_NONE:
        return {""};
    }
    return {""};
}

csubstr from_tag(YamlTag_e tag)
{
    switch(tag)
    {
    case TAG_MAP:
        return {"!!map"};
    case TAG_OMAP:
        return {"!!omap"};
    case TAG_PAIRS:
        return {"!!pairs"};
    case TAG_SET:
        return {"!!set"};
    case TAG_SEQ:
        return {"!!seq"};
    case TAG_BINARY:
        return {"!!binary"};
    case TAG_BOOL:
        return {"!!bool"};
    case TAG_FLOAT:
        return {"!!float"};
    case TAG_INT:
        return {"!!int"};
    case TAG_MERGE:
        return {"!!merge"};
    case TAG_NULL:
        return {"!!null"};
    case TAG_STR:
        return {"!!str"};
    case TAG_TIMESTAMP:
        return {"!!timestamp"};
    case TAG_VALUE:
        return {"!!value"};
    case TAG_YAML:
        return {"!!yaml"};
    case TAG_NONE:
        return {""};
    }
    return {""};
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

const char* NodeType::type_str(NodeType_e ty)
{
    switch(ty & _TYMASK)
    {
    case KEYVAL:
        return "KEYVAL";
    case KEY:
        return "KEY";
    case VAL:
        return "VAL";
    case MAP:
        return "MAP";
    case SEQ:
        return "SEQ";
    case KEYMAP:
        return "KEYMAP";
    case KEYSEQ:
        return "KEYSEQ";
    case DOCSEQ:
        return "DOCSEQ";
    case DOCMAP:
        return "DOCMAP";
    case DOCVAL:
        return "DOCVAL";
    case DOC:
        return "DOC";
    case STREAM:
        return "STREAM";
    case NOTYPE:
        return "NOTYPE";
    default:
        if((ty & KEYVAL) == KEYVAL)
            return "KEYVAL***";
        if((ty & KEYMAP) == KEYMAP)
            return "KEYMAP***";
        if((ty & KEYSEQ) == KEYSEQ)
            return "KEYSEQ***";
        if((ty & DOCSEQ) == DOCSEQ)
            return "DOCSEQ***";
        if((ty & DOCMAP) == DOCMAP)
            return "DOCMAP***";
        if((ty & DOCVAL) == DOCVAL)
            return "DOCVAL***";
        if(ty & KEY)
            return "KEY***";
        if(ty & VAL)
            return "VAL***";
        if(ty & MAP)
            return "MAP***";
        if(ty & SEQ)
            return "SEQ***";
        if(ty & DOC)
            return "DOC***";
        return "(unk)";
    }
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

NodeRef Tree::rootref()
{
    return NodeRef(this, root_id());
}
ConstNodeRef Tree::rootref() const
{
    return ConstNodeRef(this, root_id());
}

ConstNodeRef Tree::crootref()
{
    return ConstNodeRef(this, root_id());
}
ConstNodeRef Tree::crootref() const
{
    return ConstNodeRef(this, root_id());
}

NodeRef Tree::ref(size_t id)
{
    _RYML_CB_ASSERT(m_callbacks, id != NONE && id >= 0 && id < m_size);
    return NodeRef(this, id);
}
ConstNodeRef Tree::ref(size_t id) const
{
    _RYML_CB_ASSERT(m_callbacks, id != NONE && id >= 0 && id < m_size);
    return ConstNodeRef(this, id);
}

ConstNodeRef Tree::cref(size_t id)
{
    _RYML_CB_ASSERT(m_callbacks, id != NONE && id >= 0 && id < m_size);
    return ConstNodeRef(this, id);
}
ConstNodeRef Tree::cref(size_t id) const
{
    _RYML_CB_ASSERT(m_callbacks, id != NONE && id >= 0 && id < m_size);
    return ConstNodeRef(this, id);
}

NodeRef Tree::operator[] (csubstr key)
{
    return rootref()[key];
}
ConstNodeRef Tree::operator[] (csubstr key) const
{
    return rootref()[key];
}

NodeRef Tree::operator[] (size_t i)
{
    return rootref()[i];
}
ConstNodeRef Tree::operator[] (size_t i) const
{
    return rootref()[i];
}

NodeRef Tree::docref(size_t i)
{
    return ref(doc(i));
}
ConstNodeRef Tree::docref(size_t i) const
{
    return cref(doc(i));
}


//-----------------------------------------------------------------------------
Tree::Tree(Callbacks const& cb)
    : m_buf(nullptr)
    , m_cap(0)
    , m_size(0)
    , m_free_head(NONE)
    , m_free_tail(NONE)
    , m_arena()
    , m_arena_pos(0)
    , m_callbacks(cb)
{
}

Tree::Tree(size_t node_capacity, size_t arena_capacity, Callbacks const& cb)
    : Tree(cb)
{
    reserve(node_capacity);
    reserve_arena(arena_capacity);
}

Tree::~Tree()
{
    _free();
}


Tree::Tree(Tree const& that) noexcept : Tree(that.m_callbacks)
{
    _copy(that);
}

Tree& Tree::operator= (Tree const& that) noexcept
{
    _free();
    m_callbacks = that.m_callbacks;
    _copy(that);
    return *this;
}

Tree::Tree(Tree && that) noexcept : Tree(that.m_callbacks)
{
    _move(that);
}

Tree& Tree::operator= (Tree && that) noexcept
{
    _free();
    m_callbacks = that.m_callbacks;
    _move(that);
    return *this;
}

void Tree::_free()
{
    if(m_buf)
    {
        _RYML_CB_ASSERT(m_callbacks, m_cap > 0);
        _RYML_CB_FREE(m_callbacks, m_buf, NodeData, m_cap);
    }
    if(m_arena.str)
    {
        _RYML_CB_ASSERT(m_callbacks, m_arena.len > 0);
        _RYML_CB_FREE(m_callbacks, m_arena.str, char, m_arena.len);
    }
    _clear();
}


C4_SUPPRESS_WARNING_GCC_PUSH
#if defined(__GNUC__) && __GNUC__>= 8
    C4_SUPPRESS_WARNING_GCC_WITH_PUSH("-Wclass-memaccess") // error: ‘void* memset(void*, int, size_t)’ clearing an object of type ‘class c4::yml::Tree’ with no trivial copy-assignment; use assignment or value-initialization instead
#endif

void Tree::_clear()
{
    m_buf = nullptr;
    m_cap = 0;
    m_size = 0;
    m_free_head = 0;
    m_free_tail = 0;
    m_arena = {};
    m_arena_pos = 0;
    for(size_t i = 0; i < RYML_MAX_TAG_DIRECTIVES; ++i)
        m_tag_directives[i] = {};
}

void Tree::_copy(Tree const& that)
{
    _RYML_CB_ASSERT(m_callbacks, m_buf == nullptr);
    _RYML_CB_ASSERT(m_callbacks, m_arena.str == nullptr);
    _RYML_CB_ASSERT(m_callbacks, m_arena.len == 0);
    m_buf = _RYML_CB_ALLOC_HINT(m_callbacks, NodeData, that.m_cap, that.m_buf);
    memcpy(m_buf, that.m_buf, that.m_cap * sizeof(NodeData));
    m_cap = that.m_cap;
    m_size = that.m_size;
    m_free_head = that.m_free_head;
    m_free_tail = that.m_free_tail;
    m_arena_pos = that.m_arena_pos;
    m_arena = that.m_arena;
    if(that.m_arena.str)
    {
        _RYML_CB_ASSERT(m_callbacks, that.m_arena.len > 0);
        substr arena;
        arena.str = _RYML_CB_ALLOC_HINT(m_callbacks, char, that.m_arena.len, that.m_arena.str);
        arena.len = that.m_arena.len;
        _relocate(arena); // does a memcpy of the arena and updates nodes using the old arena
        m_arena = arena;
    }
    for(size_t i = 0; i < RYML_MAX_TAG_DIRECTIVES; ++i)
        m_tag_directives[i] = that.m_tag_directives[i];
}

void Tree::_move(Tree & that)
{
    _RYML_CB_ASSERT(m_callbacks, m_buf == nullptr);
    _RYML_CB_ASSERT(m_callbacks, m_arena.str == nullptr);
    _RYML_CB_ASSERT(m_callbacks, m_arena.len == 0);
    m_buf = that.m_buf;
    m_cap = that.m_cap;
    m_size = that.m_size;
    m_free_head = that.m_free_head;
    m_free_tail = that.m_free_tail;
    m_arena = that.m_arena;
    m_arena_pos = that.m_arena_pos;
    for(size_t i = 0; i < RYML_MAX_TAG_DIRECTIVES; ++i)
        m_tag_directives[i] = that.m_tag_directives[i];
    that._clear();
}

void Tree::_relocate(substr next_arena)
{
    _RYML_CB_ASSERT(m_callbacks, next_arena.not_empty());
    _RYML_CB_ASSERT(m_callbacks, next_arena.len >= m_arena.len);
    memcpy(next_arena.str, m_arena.str, m_arena_pos);
    for(NodeData *C4_RESTRICT n = m_buf, *e = m_buf + m_cap; n != e; ++n)
    {
        if(in_arena(n->m_key.scalar))
            n->m_key.scalar = _relocated(n->m_key.scalar, next_arena);
        if(in_arena(n->m_key.tag))
            n->m_key.tag = _relocated(n->m_key.tag, next_arena);
        if(in_arena(n->m_key.anchor))
            n->m_key.anchor = _relocated(n->m_key.anchor, next_arena);
        if(in_arena(n->m_val.scalar))
            n->m_val.scalar = _relocated(n->m_val.scalar, next_arena);
        if(in_arena(n->m_val.tag))
            n->m_val.tag = _relocated(n->m_val.tag, next_arena);
        if(in_arena(n->m_val.anchor))
            n->m_val.anchor = _relocated(n->m_val.anchor, next_arena);
    }
    for(TagDirective &C4_RESTRICT td : m_tag_directives)
    {
        if(in_arena(td.prefix))
            td.prefix = _relocated(td.prefix, next_arena);
        if(in_arena(td.handle))
            td.handle = _relocated(td.handle, next_arena);
    }
}


//-----------------------------------------------------------------------------
void Tree::reserve(size_t cap)
{
    if(cap > m_cap)
    {
        NodeData *buf = _RYML_CB_ALLOC_HINT(m_callbacks, NodeData, cap, m_buf);
        if(m_buf)
        {
            memcpy(buf, m_buf, m_cap * sizeof(NodeData));
            _RYML_CB_FREE(m_callbacks, m_buf, NodeData, m_cap);
        }
        size_t first = m_cap, del = cap - m_cap;
        m_cap = cap;
        m_buf = buf;
        _clear_range(first, del);
        if(m_free_head != NONE)
        {
            _RYML_CB_ASSERT(m_callbacks, m_buf != nullptr);
            _RYML_CB_ASSERT(m_callbacks, m_free_tail != NONE);
            m_buf[m_free_tail].m_next_sibling = first;
            m_buf[first].m_prev_sibling = m_free_tail;
            m_free_tail = cap-1;
        }
        else
        {
            _RYML_CB_ASSERT(m_callbacks, m_free_tail == NONE);
            m_free_head = first;
            m_free_tail = cap-1;
        }
        _RYML_CB_ASSERT(m_callbacks, m_free_head == NONE || (m_free_head >= 0 && m_free_head < cap));
        _RYML_CB_ASSERT(m_callbacks, m_free_tail == NONE || (m_free_tail >= 0 && m_free_tail < cap));

        if( ! m_size)
            _claim_root();
    }
}


//-----------------------------------------------------------------------------
void Tree::clear()
{
    _clear_range(0, m_cap);
    m_size = 0;
    if(m_buf)
    {
        _RYML_CB_ASSERT(m_callbacks, m_cap >= 0);
        m_free_head = 0;
        m_free_tail = m_cap-1;
        _claim_root();
    }
    else
    {
        m_free_head = NONE;
        m_free_tail = NONE;
    }
    for(size_t i = 0; i < RYML_MAX_TAG_DIRECTIVES; ++i)
        m_tag_directives[i] = {};
}

void Tree::_claim_root()
{
    size_t r = _claim();
    _RYML_CB_ASSERT(m_callbacks, r == 0);
    _set_hierarchy(r, NONE, NONE);
}


//-----------------------------------------------------------------------------
void Tree::_clear_range(size_t first, size_t num)
{
    if(num == 0)
        return; // prevent overflow when subtracting
    _RYML_CB_ASSERT(m_callbacks, first >= 0 && first + num <= m_cap);
    memset(m_buf + first, 0, num * sizeof(NodeData)); // TODO we should not need this
    for(size_t i = first, e = first + num; i < e; ++i)
    {
        _clear(i);
        NodeData *n = m_buf + i;
        n->m_prev_sibling = i - 1;
        n->m_next_sibling = i + 1;
    }
    m_buf[first + num - 1].m_next_sibling = NONE;
}

C4_SUPPRESS_WARNING_GCC_POP


//-----------------------------------------------------------------------------
void Tree::_release(size_t i)
{
    _RYML_CB_ASSERT(m_callbacks, i >= 0 && i < m_cap);

    _rem_hierarchy(i);
    _free_list_add(i);
    _clear(i);

    --m_size;
}

//-----------------------------------------------------------------------------
// add to the front of the free list
void Tree::_free_list_add(size_t i)
{
    _RYML_CB_ASSERT(m_callbacks, i >= 0 && i < m_cap);
    NodeData &C4_RESTRICT w = m_buf[i];

    w.m_parent = NONE;
    w.m_next_sibling = m_free_head;
    w.m_prev_sibling = NONE;
    if(m_free_head != NONE)
        m_buf[m_free_head].m_prev_sibling = i;
    m_free_head = i;
    if(m_free_tail == NONE)
        m_free_tail = m_free_head;
}

void Tree::_free_list_rem(size_t i)
{
    if(m_free_head == i)
        m_free_head = _p(i)->m_next_sibling;
    _rem_hierarchy(i);
}

//-----------------------------------------------------------------------------
size_t Tree::_claim()
{
    if(m_free_head == NONE || m_buf == nullptr)
    {
        size_t sz = 2 * m_cap;
        sz = sz ? sz : 16;
        reserve(sz);
        _RYML_CB_ASSERT(m_callbacks, m_free_head != NONE);
    }

    _RYML_CB_ASSERT(m_callbacks, m_size < m_cap);
    _RYML_CB_ASSERT(m_callbacks, m_free_head >= 0 && m_free_head < m_cap);

    size_t ichild = m_free_head;
    NodeData *child = m_buf + ichild;

    ++m_size;
    m_free_head = child->m_next_sibling;
    if(m_free_head == NONE)
    {
        m_free_tail = NONE;
        _RYML_CB_ASSERT(m_callbacks, m_size == m_cap);
    }

    _clear(ichild);

    return ichild;
}

//-----------------------------------------------------------------------------

C4_SUPPRESS_WARNING_GCC_PUSH
C4_SUPPRESS_WARNING_CLANG_PUSH
C4_SUPPRESS_WARNING_CLANG("-Wnull-dereference")
#if defined(__GNUC__) && (__GNUC__ >= 6)
C4_SUPPRESS_WARNING_GCC("-Wnull-dereference")
#endif

void Tree::_set_hierarchy(size_t ichild, size_t iparent, size_t iprev_sibling)
{
    _RYML_CB_ASSERT(m_callbacks, iparent == NONE || (iparent >= 0 && iparent < m_cap));
    _RYML_CB_ASSERT(m_callbacks, iprev_sibling == NONE || (iprev_sibling >= 0 && iprev_sibling < m_cap));

    NodeData *C4_RESTRICT child = get(ichild);

    child->m_parent = iparent;
    child->m_prev_sibling = NONE;
    child->m_next_sibling = NONE;

    if(iparent == NONE)
    {
        _RYML_CB_ASSERT(m_callbacks, ichild == 0);
        _RYML_CB_ASSERT(m_callbacks, iprev_sibling == NONE);
    }

    if(iparent == NONE)
        return;

    size_t inext_sibling = iprev_sibling != NONE ? next_sibling(iprev_sibling) : first_child(iparent);
    NodeData *C4_RESTRICT parent = get(iparent);
    NodeData *C4_RESTRICT psib   = get(iprev_sibling);
    NodeData *C4_RESTRICT nsib   = get(inext_sibling);

    if(psib)
    {
        _RYML_CB_ASSERT(m_callbacks, next_sibling(iprev_sibling) == id(nsib));
        child->m_prev_sibling = id(psib);
        psib->m_next_sibling = id(child);
        _RYML_CB_ASSERT(m_callbacks, psib->m_prev_sibling != psib->m_next_sibling || psib->m_prev_sibling == NONE);
    }

    if(nsib)
    {
        _RYML_CB_ASSERT(m_callbacks, prev_sibling(inext_sibling) == id(psib));
        child->m_next_sibling = id(nsib);
        nsib->m_prev_sibling = id(child);
        _RYML_CB_ASSERT(m_callbacks, nsib->m_prev_sibling != nsib->m_next_sibling || nsib->m_prev_sibling == NONE);
    }

    if(parent->m_first_child == NONE)
    {
        _RYML_CB_ASSERT(m_callbacks, parent->m_last_child == NONE);
        parent->m_first_child = id(child);
        parent->m_last_child = id(child);
    }
    else
    {
        if(child->m_next_sibling == parent->m_first_child)
            parent->m_first_child = id(child);

        if(child->m_prev_sibling == parent->m_last_child)
            parent->m_last_child = id(child);
    }
}

C4_SUPPRESS_WARNING_GCC_POP
C4_SUPPRESS_WARNING_CLANG_POP


//-----------------------------------------------------------------------------
void Tree::_rem_hierarchy(size_t i)
{
    _RYML_CB_ASSERT(m_callbacks, i >= 0 && i < m_cap);

    NodeData &C4_RESTRICT w = m_buf[i];

    // remove from the parent
    if(w.m_parent != NONE)
    {
        NodeData &C4_RESTRICT p = m_buf[w.m_parent];
        if(p.m_first_child == i)
        {
            p.m_first_child = w.m_next_sibling;
        }
        if(p.m_last_child == i)
        {
            p.m_last_child = w.m_prev_sibling;
        }
    }

    // remove from the used list
    if(w.m_prev_sibling != NONE)
    {
        NodeData *C4_RESTRICT prev = get(w.m_prev_sibling);
        prev->m_next_sibling = w.m_next_sibling;
    }
    if(w.m_next_sibling != NONE)
    {
        NodeData *C4_RESTRICT next = get(w.m_next_sibling);
        next->m_prev_sibling = w.m_prev_sibling;
    }
}

//-----------------------------------------------------------------------------
void Tree::reorder()
{
    size_t r = root_id();
    _do_reorder(&r, 0);
}

//-----------------------------------------------------------------------------
size_t Tree::_do_reorder(size_t *node, size_t count)
{
    // swap this node if it's not in place
    if(*node != count)
    {
        _swap(*node, count);
        *node = count;
    }
    ++count; // bump the count from this node

    // now descend in the hierarchy
    for(size_t i = first_child(*node); i != NONE; i = next_sibling(i))
    {
        // this child may have been relocated to a different index,
        // so get an updated version
        count = _do_reorder(&i, count);
    }
    return count;
}

//-----------------------------------------------------------------------------
void Tree::_swap(size_t n_, size_t m_)
{
    _RYML_CB_ASSERT(m_callbacks, (parent(n_) != NONE) || type(n_) == NOTYPE);
    _RYML_CB_ASSERT(m_callbacks, (parent(m_) != NONE) || type(m_) == NOTYPE);
    NodeType tn = type(n_);
    NodeType tm = type(m_);
    if(tn != NOTYPE && tm != NOTYPE)
    {
        _swap_props(n_, m_);
        _swap_hierarchy(n_, m_);
    }
    else if(tn == NOTYPE && tm != NOTYPE)
    {
        _copy_props(n_, m_);
        _free_list_rem(n_);
        _copy_hierarchy(n_, m_);
        _clear(m_);
        _free_list_add(m_);
    }
    else if(tn != NOTYPE && tm == NOTYPE)
    {
        _copy_props(m_, n_);
        _free_list_rem(m_);
        _copy_hierarchy(m_, n_);
        _clear(n_);
        _free_list_add(n_);
    }
    else
    {
        C4_NEVER_REACH();
    }
}

//-----------------------------------------------------------------------------
void Tree::_swap_hierarchy(size_t ia, size_t ib)
{
    if(ia == ib) return;

    for(size_t i = first_child(ia); i != NONE; i = next_sibling(i))
    {
        if(i == ib || i == ia)
            continue;
        _p(i)->m_parent = ib;
    }

    for(size_t i = first_child(ib); i != NONE; i = next_sibling(i))
    {
        if(i == ib || i == ia)
            continue;
        _p(i)->m_parent = ia;
    }

    auto & C4_RESTRICT a  = *_p(ia);
    auto & C4_RESTRICT b  = *_p(ib);
    auto & C4_RESTRICT pa = *_p(a.m_parent);
    auto & C4_RESTRICT pb = *_p(b.m_parent);

    if(&pa == &pb)
    {
        if((pa.m_first_child == ib && pa.m_last_child == ia)
            ||
           (pa.m_first_child == ia && pa.m_last_child == ib))
        {
            std::swap(pa.m_first_child, pa.m_last_child);
        }
        else
        {
            bool changed = false;
            if(pa.m_first_child == ia)
            {
                pa.m_first_child = ib;
                changed = true;
            }
            if(pa.m_last_child  == ia)
            {
                pa.m_last_child = ib;
                changed = true;
            }
            if(pb.m_first_child == ib && !changed)
            {
                pb.m_first_child = ia;
            }
            if(pb.m_last_child  == ib && !changed)
            {
                pb.m_last_child  = ia;
            }
        }
    }
    else
    {
        if(pa.m_first_child == ia)
            pa.m_first_child = ib;
        if(pa.m_last_child  == ia)
            pa.m_last_child  = ib;
        if(pb.m_first_child == ib)
            pb.m_first_child = ia;
        if(pb.m_last_child  == ib)
            pb.m_last_child  = ia;
    }
    std::swap(a.m_first_child , b.m_first_child);
    std::swap(a.m_last_child  , b.m_last_child);

    if(a.m_prev_sibling != ib && b.m_prev_sibling != ia &&
       a.m_next_sibling != ib && b.m_next_sibling != ia)
    {
        if(a.m_prev_sibling != NONE && a.m_prev_sibling != ib)
            _p(a.m_prev_sibling)->m_next_sibling = ib;
        if(a.m_next_sibling != NONE && a.m_next_sibling != ib)
            _p(a.m_next_sibling)->m_prev_sibling = ib;
        if(b.m_prev_sibling != NONE && b.m_prev_sibling != ia)
            _p(b.m_prev_sibling)->m_next_sibling = ia;
        if(b.m_next_sibling != NONE && b.m_next_sibling != ia)
            _p(b.m_next_sibling)->m_prev_sibling = ia;
        std::swap(a.m_prev_sibling, b.m_prev_sibling);
        std::swap(a.m_next_sibling, b.m_next_sibling);
    }
    else
    {
        if(a.m_next_sibling == ib) // n will go after m
        {
            _RYML_CB_ASSERT(m_callbacks, b.m_prev_sibling == ia);
            if(a.m_prev_sibling != NONE)
            {
                _RYML_CB_ASSERT(m_callbacks, a.m_prev_sibling != ib);
                _p(a.m_prev_sibling)->m_next_sibling = ib;
            }
            if(b.m_next_sibling != NONE)
            {
                _RYML_CB_ASSERT(m_callbacks, b.m_next_sibling != ia);
                _p(b.m_next_sibling)->m_prev_sibling = ia;
            }
            size_t ns = b.m_next_sibling;
            b.m_prev_sibling = a.m_prev_sibling;
            b.m_next_sibling = ia;
            a.m_prev_sibling = ib;
            a.m_next_sibling = ns;
        }
        else if(a.m_prev_sibling == ib) // m will go after n
        {
            _RYML_CB_ASSERT(m_callbacks, b.m_next_sibling == ia);
            if(b.m_prev_sibling != NONE)
            {
                _RYML_CB_ASSERT(m_callbacks, b.m_prev_sibling != ia);
                _p(b.m_prev_sibling)->m_next_sibling = ia;
            }
            if(a.m_next_sibling != NONE)
            {
                _RYML_CB_ASSERT(m_callbacks, a.m_next_sibling != ib);
                _p(a.m_next_sibling)->m_prev_sibling = ib;
            }
            size_t ns = b.m_prev_sibling;
            a.m_prev_sibling = b.m_prev_sibling;
            a.m_next_sibling = ib;
            b.m_prev_sibling = ia;
            b.m_next_sibling = ns;
        }
        else
        {
            C4_NEVER_REACH();
        }
    }
    _RYML_CB_ASSERT(m_callbacks, a.m_next_sibling != ia);
    _RYML_CB_ASSERT(m_callbacks, a.m_prev_sibling != ia);
    _RYML_CB_ASSERT(m_callbacks, b.m_next_sibling != ib);
    _RYML_CB_ASSERT(m_callbacks, b.m_prev_sibling != ib);

    if(a.m_parent != ib && b.m_parent != ia)
    {
        std::swap(a.m_parent, b.m_parent);
    }
    else
    {
        if(a.m_parent == ib && b.m_parent != ia)
        {
            a.m_parent = b.m_parent;
            b.m_parent = ia;
        }
        else if(a.m_parent != ib && b.m_parent == ia)
        {
            b.m_parent = a.m_parent;
            a.m_parent = ib;
        }
        else
        {
            C4_NEVER_REACH();
        }
    }
}

//-----------------------------------------------------------------------------
void Tree::_copy_hierarchy(size_t dst_, size_t src_)
{
    auto const& C4_RESTRICT src = *_p(src_);
    auto      & C4_RESTRICT dst = *_p(dst_);
    auto      & C4_RESTRICT prt = *_p(src.m_parent);
    for(size_t i = src.m_first_child; i != NONE; i = next_sibling(i))
    {
        _p(i)->m_parent = dst_;
    }
    if(src.m_prev_sibling != NONE)
    {
        _p(src.m_prev_sibling)->m_next_sibling = dst_;
    }
    if(src.m_next_sibling != NONE)
    {
        _p(src.m_next_sibling)->m_prev_sibling = dst_;
    }
    if(prt.m_first_child == src_)
    {
        prt.m_first_child = dst_;
    }
    if(prt.m_last_child  == src_)
    {
        prt.m_last_child  = dst_;
    }
    dst.m_parent       = src.m_parent;
    dst.m_first_child  = src.m_first_child;
    dst.m_last_child   = src.m_last_child;
    dst.m_prev_sibling = src.m_prev_sibling;
    dst.m_next_sibling = src.m_next_sibling;
}

//-----------------------------------------------------------------------------
void Tree::_swap_props(size_t n_, size_t m_)
{
    NodeData &C4_RESTRICT n = *_p(n_);
    NodeData &C4_RESTRICT m = *_p(m_);
    std::swap(n.m_type, m.m_type);
    std::swap(n.m_key, m.m_key);
    std::swap(n.m_val, m.m_val);
}

//-----------------------------------------------------------------------------
void Tree::move(size_t node, size_t after)
{
    _RYML_CB_ASSERT(m_callbacks, node != NONE);
    _RYML_CB_ASSERT(m_callbacks, node != after);
    _RYML_CB_ASSERT(m_callbacks,  ! is_root(node));
    _RYML_CB_ASSERT(m_callbacks, (after == NONE) || (has_sibling(node, after) && has_sibling(after, node)));

    _rem_hierarchy(node);
    _set_hierarchy(node, parent(node), after);
}

//-----------------------------------------------------------------------------

void Tree::move(size_t node, size_t new_parent, size_t after)
{
    _RYML_CB_ASSERT(m_callbacks, node != NONE);
    _RYML_CB_ASSERT(m_callbacks, node != after);
    _RYML_CB_ASSERT(m_callbacks, new_parent != NONE);
    _RYML_CB_ASSERT(m_callbacks, new_parent != node);
    _RYML_CB_ASSERT(m_callbacks, new_parent != after);
    _RYML_CB_ASSERT(m_callbacks,  ! is_root(node));

    _rem_hierarchy(node);
    _set_hierarchy(node, new_parent, after);
}

size_t Tree::move(Tree *src, size_t node, size_t new_parent, size_t after)
{
    _RYML_CB_ASSERT(m_callbacks, src != nullptr);
    _RYML_CB_ASSERT(m_callbacks, node != NONE);
    _RYML_CB_ASSERT(m_callbacks, new_parent != NONE);
    _RYML_CB_ASSERT(m_callbacks, new_parent != after);

    size_t dup = duplicate(src, node, new_parent, after);
    src->remove(node);
    return dup;
}

void Tree::set_root_as_stream()
{
    size_t root = root_id();
    if(is_stream(root))
        return;
    // don't use _add_flags() because it's checked and will fail
    if(!has_children(root))
    {
        if(is_val(root))
        {
            _p(root)->m_type.add(SEQ);
            size_t next_doc = append_child(root);
            _copy_props_wo_key(next_doc, root);
            _p(next_doc)->m_type.add(DOC);
            _p(next_doc)->m_type.rem(SEQ);
        }
        _p(root)->m_type = STREAM;
        return;
    }
    _RYML_CB_ASSERT(m_callbacks, !has_key(root));
    size_t next_doc = append_child(root);
    _copy_props_wo_key(next_doc, root);
    _add_flags(next_doc, DOC);
    for(size_t prev = NONE, ch = first_child(root), next = next_sibling(ch); ch != NONE; )
    {
        if(ch == next_doc)
            break;
        move(ch, next_doc, prev);
        prev = ch;
        ch = next;
        next = next_sibling(next);
    }
    _p(root)->m_type = STREAM;
}


//-----------------------------------------------------------------------------
void Tree::remove_children(size_t node)
{
    _RYML_CB_ASSERT(m_callbacks, get(node) != nullptr);
    size_t ich = get(node)->m_first_child;
    while(ich != NONE)
    {
        remove_children(ich);
        _RYML_CB_ASSERT(m_callbacks, get(ich) != nullptr);
        size_t next = get(ich)->m_next_sibling;
        _release(ich);
        if(ich == get(node)->m_last_child)
            break;
        ich = next;
    }
}

bool Tree::change_type(size_t node, NodeType type)
{
    _RYML_CB_ASSERT(m_callbacks, type.is_val() || type.is_map() || type.is_seq());
    _RYML_CB_ASSERT(m_callbacks, type.is_val() + type.is_map() + type.is_seq() == 1);
    _RYML_CB_ASSERT(m_callbacks, type.has_key() == has_key(node) || (has_key(node) && !type.has_key()));
    NodeData *d = _p(node);
    if(type.is_map() && is_map(node))
        return false;
    else if(type.is_seq() && is_seq(node))
        return false;
    else if(type.is_val() && is_val(node))
        return false;
    d->m_type = (d->m_type & (~(MAP|SEQ|VAL))) | type;
    remove_children(node);
    return true;
}


//-----------------------------------------------------------------------------
size_t Tree::duplicate(size_t node, size_t parent, size_t after)
{
    return duplicate(this, node, parent, after);
}

size_t Tree::duplicate(Tree const* src, size_t node, size_t parent, size_t after)
{
    _RYML_CB_ASSERT(m_callbacks, src != nullptr);
    _RYML_CB_ASSERT(m_callbacks, node != NONE);
    _RYML_CB_ASSERT(m_callbacks, parent != NONE);
    _RYML_CB_ASSERT(m_callbacks,  ! src->is_root(node));

    size_t copy = _claim();

    _copy_props(copy, src, node);
    _set_hierarchy(copy, parent, after);
    duplicate_children(src, node, copy, NONE);

    return copy;
}

//-----------------------------------------------------------------------------
size_t Tree::duplicate_children(size_t node, size_t parent, size_t after)
{
    return duplicate_children(this, node, parent, after);
}

size_t Tree::duplicate_children(Tree const* src, size_t node, size_t parent, size_t after)
{
    _RYML_CB_ASSERT(m_callbacks, src != nullptr);
    _RYML_CB_ASSERT(m_callbacks, node != NONE);
    _RYML_CB_ASSERT(m_callbacks, parent != NONE);
    _RYML_CB_ASSERT(m_callbacks, after == NONE || has_child(parent, after));

    size_t prev = after;
    for(size_t i = src->first_child(node); i != NONE; i = src->next_sibling(i))
    {
        prev = duplicate(src, i, parent, prev);
    }

    return prev;
}

//-----------------------------------------------------------------------------
void Tree::duplicate_contents(size_t node, size_t where)
{
    duplicate_contents(this, node, where);
}

void Tree::duplicate_contents(Tree const *src, size_t node, size_t where)
{
    _RYML_CB_ASSERT(m_callbacks, src != nullptr);
    _RYML_CB_ASSERT(m_callbacks, node != NONE);
    _RYML_CB_ASSERT(m_callbacks, where != NONE);
    _copy_props_wo_key(where, src, node);
    duplicate_children(src, node, where, last_child(where));
}

//-----------------------------------------------------------------------------
size_t Tree::duplicate_children_no_rep(size_t node, size_t parent, size_t after)
{
    return duplicate_children_no_rep(this, node, parent, after);
}

size_t Tree::duplicate_children_no_rep(Tree const *src, size_t node, size_t parent, size_t after)
{
    _RYML_CB_ASSERT(m_callbacks, node != NONE);
    _RYML_CB_ASSERT(m_callbacks, parent != NONE);
    _RYML_CB_ASSERT(m_callbacks, after == NONE || has_child(parent, after));

    // don't loop using pointers as there may be a relocation

    // find the position where "after" is
    size_t after_pos = NONE;
    if(after != NONE)
    {
        for(size_t i = first_child(parent), icount = 0; i != NONE; ++icount, i = next_sibling(i))
        {
            if(i == after)
            {
                after_pos = icount;
                break;
            }
        }
        _RYML_CB_ASSERT(m_callbacks, after_pos != NONE);
    }

    // for each child to be duplicated...
    size_t prev = after;
    for(size_t i = src->first_child(node), icount = 0; i != NONE; ++icount, i = src->next_sibling(i))
    {
        if(is_seq(parent))
        {
            prev = duplicate(i, parent, prev);
        }
        else
        {
            _RYML_CB_ASSERT(m_callbacks, is_map(parent));
            // does the parent already have a node with key equal to that of the current duplicate?
            size_t rep = NONE, rep_pos = NONE;
            for(size_t j = first_child(parent), jcount = 0; j != NONE; ++jcount, j = next_sibling(j))
            {
                if(key(j) == key(i))
                {
                    rep = j;
                    rep_pos = jcount;
                    break;
                }
            }
            if(rep == NONE) // there is no repetition; just duplicate
            {
                prev = duplicate(src, i, parent, prev);
            }
            else  // yes, there is a repetition
            {
                if(after_pos != NONE && rep_pos < after_pos)
                {
                    // rep is located before the node which will be inserted,
                    // and will be overridden by the duplicate. So replace it.
                    remove(rep);
                    prev = duplicate(src, i, parent, prev);
                }
                else if(prev == NONE)
                {
                    // first iteration with prev = after = NONE and repetition
                    prev = rep;
                }
                else if(rep != prev)
                {
                    // rep is located after the node which will be inserted
                    // and overrides it. So move the rep into this node's place.
                    move(rep, prev);
                    prev = rep;
                }
            } // there's a repetition
        }
    }

    return prev;
}


//-----------------------------------------------------------------------------

void Tree::merge_with(Tree const *src, size_t src_node, size_t dst_node)
{
    _RYML_CB_ASSERT(m_callbacks, src != nullptr);
    if(src_node == NONE)
        src_node = src->root_id();
    if(dst_node == NONE)
        dst_node = root_id();
    _RYML_CB_ASSERT(m_callbacks, src->has_val(src_node) || src->is_seq(src_node) || src->is_map(src_node));

    if(src->has_val(src_node))
    {
        if( ! has_val(dst_node))
        {
            if(has_children(dst_node))
                remove_children(dst_node);
        }
        if(src->is_keyval(src_node))
            _copy_props(dst_node, src, src_node);
        else if(src->is_val(src_node))
            _copy_props_wo_key(dst_node, src, src_node);
        else
            C4_NEVER_REACH();
    }
    else if(src->is_seq(src_node))
    {
        if( ! is_seq(dst_node))
        {
            if(has_children(dst_node))
                remove_children(dst_node);
            _clear_type(dst_node);
            if(src->has_key(src_node))
                to_seq(dst_node, src->key(src_node));
            else
                to_seq(dst_node);
        }
        for(size_t sch = src->first_child(src_node); sch != NONE; sch = src->next_sibling(sch))
        {
            size_t dch = append_child(dst_node);
            _copy_props_wo_key(dch, src, sch);
            merge_with(src, sch, dch);
        }
    }
    else if(src->is_map(src_node))
    {
        if( ! is_map(dst_node))
        {
            if(has_children(dst_node))
                remove_children(dst_node);
            _clear_type(dst_node);
            if(src->has_key(src_node))
                to_map(dst_node, src->key(src_node));
            else
                to_map(dst_node);
        }
        for(size_t sch = src->first_child(src_node); sch != NONE; sch = src->next_sibling(sch))
        {
            size_t dch = find_child(dst_node, src->key(sch));
            if(dch == NONE)
            {
                dch = append_child(dst_node);
                _copy_props(dch, src, sch);
            }
            merge_with(src, sch, dch);
        }
    }
    else
    {
        C4_NEVER_REACH();
    }
}


//-----------------------------------------------------------------------------

namespace detail {
/** @todo make this part of the public API, refactoring as appropriate
 * to be able to use the same resolver to handle multiple trees (one
 * at a time) */
struct ReferenceResolver
{
    struct refdata
    {
        NodeType type;
        size_t node;
        size_t prev_anchor;
        size_t target;
        size_t parent_ref;
        size_t parent_ref_sibling;
    };

    Tree *t;
    /** from the specs: "an alias node refers to the most recent
     * node in the serialization having the specified anchor". So
     * we need to start looking upward from ref nodes.
     *
     * @see http://yaml.org/spec/1.2/spec.html#id2765878 */
    stack<refdata> refs;

    ReferenceResolver(Tree *t_) : t(t_), refs(t_->callbacks())
    {
        resolve();
    }

    void store_anchors_and_refs()
    {
        // minimize (re-)allocations by counting first
        size_t num_anchors_and_refs = count_anchors_and_refs(t->root_id());
        if(!num_anchors_and_refs)
            return;
        refs.reserve(num_anchors_and_refs);

        // now descend through the hierarchy
        _store_anchors_and_refs(t->root_id());

        // finally connect the reference list
        size_t prev_anchor = npos;
        size_t count = 0;
        for(auto &rd : refs)
        {
            rd.prev_anchor = prev_anchor;
            if(rd.type.is_anchor())
                prev_anchor = count;
            ++count;
        }
    }

    size_t count_anchors_and_refs(size_t n)
    {
        size_t c = 0;
        c += t->has_key_anchor(n);
        c += t->has_val_anchor(n);
        c += t->is_key_ref(n);
        c += t->is_val_ref(n);
        for(size_t ch = t->first_child(n); ch != NONE; ch = t->next_sibling(ch))
            c += count_anchors_and_refs(ch);
        return c;
    }

    void _store_anchors_and_refs(size_t n)
    {
        if(t->is_key_ref(n) || t->is_val_ref(n) || (t->has_key(n) && t->key(n) == "<<"))
        {
            if(t->is_seq(n))
            {
                // for merging multiple inheritance targets
                //   <<: [ *CENTER, *BIG ]
                for(size_t ich = t->first_child(n); ich != NONE; ich = t->next_sibling(ich))
                {
                    RYML_ASSERT(t->num_children(ich) == 0);
                    refs.push({VALREF, ich, npos, npos, n, t->next_sibling(n)});
                }
                return;
            }
            if(t->is_key_ref(n) && t->key(n) != "<<") // insert key refs BEFORE inserting val refs
            {
                RYML_CHECK((!t->has_key(n)) || t->key(n).ends_with(t->key_ref(n)));
                refs.push({KEYREF, n, npos, npos, NONE, NONE});
            }
            if(t->is_val_ref(n))
            {
                RYML_CHECK((!t->has_val(n)) || t->val(n).ends_with(t->val_ref(n)));
                refs.push({VALREF, n, npos, npos, NONE, NONE});
            }
        }
        if(t->has_key_anchor(n))
        {
            RYML_CHECK(t->has_key(n));
            refs.push({KEYANCH, n, npos, npos, NONE, NONE});
        }
        if(t->has_val_anchor(n))
        {
            RYML_CHECK(t->has_val(n) || t->is_container(n));
            refs.push({VALANCH, n, npos, npos, NONE, NONE});
        }
        for(size_t ch = t->first_child(n); ch != NONE; ch = t->next_sibling(ch))
        {
            _store_anchors_and_refs(ch);
        }
    }

    size_t lookup_(refdata *C4_RESTRICT ra)
    {
        RYML_ASSERT(ra->type.is_key_ref() || ra->type.is_val_ref());
        RYML_ASSERT(ra->type.is_key_ref() != ra->type.is_val_ref());
        csubstr refname;
        if(ra->type.is_val_ref())
        {
            refname = t->val_ref(ra->node);
        }
        else
        {
            RYML_ASSERT(ra->type.is_key_ref());
            refname = t->key_ref(ra->node);
        }
        while(ra->prev_anchor != npos)
        {
            ra = &refs[ra->prev_anchor];
            if(t->has_anchor(ra->node, refname))
                return ra->node;
        }

        #ifndef RYML_ERRMSG_SIZE
          #define RYML_ERRMSG_SIZE 1024
        #endif

        char errmsg[RYML_ERRMSG_SIZE];
        snprintf(errmsg, RYML_ERRMSG_SIZE, "anchor does not exist: '%.*s'",
                 static_cast<int>(refname.size()), refname.data());
        c4::yml::error(errmsg);
        return NONE;
    }

    void resolve()
    {
        store_anchors_and_refs();
        if(refs.empty())
            return;

        /* from the specs: "an alias node refers to the most recent
         * node in the serialization having the specified anchor". So
         * we need to start looking upward from ref nodes.
         *
         * @see http://yaml.org/spec/1.2/spec.html#id2765878 */
        for(size_t i = 0, e = refs.size(); i < e; ++i)
        {
            auto &C4_RESTRICT rd = refs.top(i);
            if( ! rd.type.is_ref())
                continue;
            rd.target = lookup_(&rd);
        }
    }

}; // ReferenceResolver
} // namespace detail

void Tree::resolve()
{
    if(m_size == 0)
        return;

    detail::ReferenceResolver rr(this);

    // insert the resolved references
    size_t prev_parent_ref = NONE;
    size_t prev_parent_ref_after = NONE;
    for(auto const& C4_RESTRICT rd : rr.refs)
    {
        if( ! rd.type.is_ref())
            continue;
        if(rd.parent_ref != NONE)
        {
            _RYML_CB_ASSERT(m_callbacks, is_seq(rd.parent_ref));
            size_t after, p = parent(rd.parent_ref);
            if(prev_parent_ref != rd.parent_ref)
            {
                after = rd.parent_ref;//prev_sibling(rd.parent_ref_sibling);
                prev_parent_ref_after = after;
            }
            else
            {
                after = prev_parent_ref_after;
            }
            prev_parent_ref = rd.parent_ref;
            prev_parent_ref_after = duplicate_children_no_rep(rd.target, p, after);
            remove(rd.node);
        }
        else
        {
            if(has_key(rd.node) && is_key_ref(rd.node) && key(rd.node) == "<<")
            {
                _RYML_CB_ASSERT(m_callbacks, is_keyval(rd.node));
                size_t p = parent(rd.node);
                size_t after = prev_sibling(rd.node);
                duplicate_children_no_rep(rd.target, p, after);
                remove(rd.node);
            }
            else if(rd.type.is_key_ref())
            {
                _RYML_CB_ASSERT(m_callbacks, is_key_ref(rd.node));
                _RYML_CB_ASSERT(m_callbacks, has_key_anchor(rd.target) || has_val_anchor(rd.target));
                if(has_val_anchor(rd.target) && val_anchor(rd.target) == key_ref(rd.node))
                {
                    _RYML_CB_CHECK(m_callbacks, !is_container(rd.target));
                    _RYML_CB_CHECK(m_callbacks, has_val(rd.target));
                    _p(rd.node)->m_key.scalar = val(rd.target);
                    _add_flags(rd.node, KEY);
                }
                else
                {
                    _RYML_CB_CHECK(m_callbacks, key_anchor(rd.target) == key_ref(rd.node));
                    _p(rd.node)->m_key.scalar = key(rd.target);
                    _add_flags(rd.node, VAL);
                }
            }
            else
            {
                _RYML_CB_ASSERT(m_callbacks, rd.type.is_val_ref());
                if(has_key_anchor(rd.target) && key_anchor(rd.target) == val_ref(rd.node))
                {
                    _RYML_CB_CHECK(m_callbacks, !is_container(rd.target));
                    _RYML_CB_CHECK(m_callbacks, has_val(rd.target));
                    _p(rd.node)->m_val.scalar = key(rd.target);
                    _add_flags(rd.node, VAL);
                }
                else
                {
                    duplicate_contents(rd.target, rd.node);
                }
            }
        }
    }

    // clear anchors and refs
    for(auto const& C4_RESTRICT ar : rr.refs)
    {
        rem_anchor_ref(ar.node);
        if(ar.parent_ref != NONE)
            if(type(ar.parent_ref) != NOTYPE)
                remove(ar.parent_ref);
    }

}

//-----------------------------------------------------------------------------

size_t Tree::num_children(size_t node) const
{
    size_t count = 0;
    for(size_t i = first_child(node); i != NONE; i = next_sibling(i))
        ++count;
    return count;
}

size_t Tree::child(size_t node, size_t pos) const
{
    _RYML_CB_ASSERT(m_callbacks, node != NONE);
    size_t count = 0;
    for(size_t i = first_child(node); i != NONE; i = next_sibling(i))
    {
        if(count++ == pos)
            return i;
    }
    return NONE;
}

size_t Tree::child_pos(size_t node, size_t ch) const
{
    size_t count = 0;
    for(size_t i = first_child(node); i != NONE; i = next_sibling(i))
    {
        if(i == ch)
            return count;
        ++count;
    }
    return npos;
}

#if defined(__clang__)
#   pragma clang diagnostic push
#   pragma GCC diagnostic ignored "-Wnull-dereference"
#elif defined(__GNUC__)
#   pragma GCC diagnostic push
#   if __GNUC__ >= 6
#       pragma GCC diagnostic ignored "-Wnull-dereference"
#   endif
#endif

size_t Tree::find_child(size_t node, csubstr const& name) const
{
    _RYML_CB_ASSERT(m_callbacks, node != NONE);
    _RYML_CB_ASSERT(m_callbacks, is_map(node));
    if(get(node)->m_first_child == NONE)
    {
        _RYML_CB_ASSERT(m_callbacks, _p(node)->m_last_child == NONE);
        return NONE;
    }
    else
    {
        _RYML_CB_ASSERT(m_callbacks, _p(node)->m_last_child != NONE);
    }
    for(size_t i = first_child(node); i != NONE; i = next_sibling(i))
    {
        if(_p(i)->m_key.scalar == name)
        {
            return i;
        }
    }
    return NONE;
}

#if defined(__clang__)
#   pragma clang diagnostic pop
#elif defined(__GNUC__)
#   pragma GCC diagnostic pop
#endif


//-----------------------------------------------------------------------------

void Tree::to_val(size_t node, csubstr val, type_bits more_flags)
{
    _RYML_CB_ASSERT(m_callbacks,  ! has_children(node));
    _RYML_CB_ASSERT(m_callbacks, parent(node) == NONE || ! parent_is_map(node));
    _set_flags(node, VAL|more_flags);
    _p(node)->m_key.clear();
    _p(node)->m_val = val;
}

void Tree::to_keyval(size_t node, csubstr key, csubstr val, type_bits more_flags)
{
    _RYML_CB_ASSERT(m_callbacks,  ! has_children(node));
    _RYML_CB_ASSERT(m_callbacks, parent(node) == NONE || parent_is_map(node));
    _set_flags(node, KEYVAL|more_flags);
    _p(node)->m_key = key;
    _p(node)->m_val = val;
}

void Tree::to_map(size_t node, type_bits more_flags)
{
    _RYML_CB_ASSERT(m_callbacks,  ! has_children(node));
    _RYML_CB_ASSERT(m_callbacks, parent(node) == NONE || ! parent_is_map(node)); // parent must not have children with keys
    _set_flags(node, MAP|more_flags);
    _p(node)->m_key.clear();
    _p(node)->m_val.clear();
}

void Tree::to_map(size_t node, csubstr key, type_bits more_flags)
{
    _RYML_CB_ASSERT(m_callbacks,  ! has_children(node));
    _RYML_CB_ASSERT(m_callbacks, parent(node) == NONE || parent_is_map(node));
    _set_flags(node, KEY|MAP|more_flags);
    _p(node)->m_key = key;
    _p(node)->m_val.clear();
}

void Tree::to_seq(size_t node, type_bits more_flags)
{
    _RYML_CB_ASSERT(m_callbacks,  ! has_children(node));
    _RYML_CB_ASSERT(m_callbacks, parent(node) == NONE || parent_is_seq(node));
    _set_flags(node, SEQ|more_flags);
    _p(node)->m_key.clear();
    _p(node)->m_val.clear();
}

void Tree::to_seq(size_t node, csubstr key, type_bits more_flags)
{
    _RYML_CB_ASSERT(m_callbacks,  ! has_children(node));
    _RYML_CB_ASSERT(m_callbacks, parent(node) == NONE || parent_is_map(node));
    _set_flags(node, KEY|SEQ|more_flags);
    _p(node)->m_key = key;
    _p(node)->m_val.clear();
}

void Tree::to_doc(size_t node, type_bits more_flags)
{
    _RYML_CB_ASSERT(m_callbacks,  ! has_children(node));
    _set_flags(node, DOC|more_flags);
    _p(node)->m_key.clear();
    _p(node)->m_val.clear();
}

void Tree::to_stream(size_t node, type_bits more_flags)
{
    _RYML_CB_ASSERT(m_callbacks,  ! has_children(node));
    _set_flags(node, STREAM|more_flags);
    _p(node)->m_key.clear();
    _p(node)->m_val.clear();
}


//-----------------------------------------------------------------------------
size_t Tree::num_tag_directives() const
{
    // this assumes we have a very small number of tag directives
    for(size_t i = 0; i < RYML_MAX_TAG_DIRECTIVES; ++i)
        if(m_tag_directives[i].handle.empty())
            return i;
    return RYML_MAX_TAG_DIRECTIVES;
}

void Tree::clear_tag_directives()
{
    for(TagDirective &td : m_tag_directives)
        td = {};
}

size_t Tree::add_tag_directive(TagDirective const& td)
{
    _RYML_CB_CHECK(m_callbacks, !td.handle.empty());
    _RYML_CB_CHECK(m_callbacks, !td.prefix.empty());
    _RYML_CB_ASSERT(m_callbacks, td.handle.begins_with('!'));
    _RYML_CB_ASSERT(m_callbacks, td.handle.ends_with('!'));
    // https://yaml.org/spec/1.2.2/#rule-ns-word-char
    _RYML_CB_ASSERT(m_callbacks, td.handle == '!' || td.handle == "!!" || td.handle.trim('!').first_not_of("01234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-") == npos);
    size_t pos = num_tag_directives();
    _RYML_CB_CHECK(m_callbacks, pos < RYML_MAX_TAG_DIRECTIVES);
    m_tag_directives[pos] = td;
    return pos;
}

size_t Tree::resolve_tag(substr output, csubstr tag, size_t node_id) const
{
    // lookup from the end. We want to find the first directive that
    // matches the tag and has a target node id leq than the given
    // node_id.
    for(size_t i = RYML_MAX_TAG_DIRECTIVES-1; i != (size_t)-1; --i)
    {
        auto const& td = m_tag_directives[i];
        if(td.handle.empty())
            continue;
        if(tag.begins_with(td.handle) && td.next_node_id <= node_id)
        {
            _RYML_CB_ASSERT(m_callbacks, tag.len >= td.handle.len);
            csubstr rest = tag.sub(td.handle.len);
            size_t len = 1u + td.prefix.len + rest.len + 1u;
            size_t numpc = rest.count('%');
            if(numpc == 0)
            {
                if(len <= output.len)
                {
                    output.str[0] = '<';
                    memcpy(1u + output.str, td.prefix.str, td.prefix.len);
                    memcpy(1u + output.str + td.prefix.len, rest.str, rest.len);
                    output.str[1u + td.prefix.len + rest.len] = '>';
                }
            }
            else
            {
                // need to decode URI % sequences
                size_t pos = rest.find('%');
                _RYML_CB_ASSERT(m_callbacks, pos != npos);
                do {
                    size_t next = rest.first_not_of("0123456789abcdefABCDEF", pos+1);
                    if(next == npos)
                        next = rest.len;
                    _RYML_CB_CHECK(m_callbacks, pos+1 < next);
                    _RYML_CB_CHECK(m_callbacks, pos+1 + 2 <= next);
                    size_t delta = next - (pos+1);
                    len -= delta;
                    pos = rest.find('%', pos+1);
                } while(pos != npos);
                if(len <= output.len)
                {
                    size_t prev = 0, wpos = 0;
                    auto appendstr = [&](csubstr s) { memcpy(output.str + wpos, s.str, s.len); wpos += s.len; };
                    auto appendchar = [&](char c) { output.str[wpos++] = c; };
                    appendchar('<');
                    appendstr(td.prefix);
                    pos = rest.find('%');
                    _RYML_CB_ASSERT(m_callbacks, pos != npos);
                    do {
                        size_t next = rest.first_not_of("0123456789abcdefABCDEF", pos+1);
                        if(next == npos)
                            next = rest.len;
                        _RYML_CB_CHECK(m_callbacks, pos+1 < next);
                        _RYML_CB_CHECK(m_callbacks, pos+1 + 2 <= next);
                        uint8_t val;
                        if(C4_UNLIKELY(!read_hex(rest.range(pos+1, next), &val) || val > 127))
                            _RYML_CB_ERR(m_callbacks, "invalid URI character");
                        appendstr(rest.range(prev, pos));
                        appendchar((char)val);
                        prev = next;
                        pos = rest.find('%', pos+1);
                    } while(pos != npos);
                    _RYML_CB_ASSERT(m_callbacks, pos == npos);
                    _RYML_CB_ASSERT(m_callbacks, prev > 0);
                    _RYML_CB_ASSERT(m_callbacks, rest.len >= prev);
                    appendstr(rest.sub(prev));
                    appendchar('>');
                    _RYML_CB_ASSERT(m_callbacks, wpos == len);
                }
            }
            return len;
        }
    }
    return 0; // return 0 to signal that the tag is local and cannot be resolved
}

namespace {
csubstr _transform_tag(Tree *t, csubstr tag, size_t node)
{
    size_t required_size = t->resolve_tag(substr{}, tag, node);
    if(!required_size)
        return tag;
    const char *prev_arena = t->arena().str;
    substr buf = t->alloc_arena(required_size);
    _RYML_CB_ASSERT(t->m_callbacks, t->arena().str == prev_arena);
    size_t actual_size = t->resolve_tag(buf, tag, node);
    _RYML_CB_ASSERT(t->m_callbacks, actual_size <= required_size);
    return buf.first(actual_size);
}
void _resolve_tags(Tree *t, size_t node)
{
    for(size_t child = t->first_child(node); child != NONE; child = t->next_sibling(child))
    {
        if(t->has_key(child) && t->has_key_tag(child))
            t->set_key_tag(child, _transform_tag(t, t->key_tag(child), child));
        if(t->has_val(child) && t->has_val_tag(child))
            t->set_val_tag(child, _transform_tag(t, t->val_tag(child), child));
        _resolve_tags(t, child);
    }
}
size_t _count_resolved_tags_size(Tree const* t, size_t node)
{
    size_t sz = 0;
    for(size_t child = t->first_child(node); child != NONE; child = t->next_sibling(child))
    {
        if(t->has_key(child) && t->has_key_tag(child))
            sz += t->resolve_tag(substr{}, t->key_tag(child), child);
        if(t->has_val(child) && t->has_val_tag(child))
            sz += t->resolve_tag(substr{}, t->val_tag(child), child);
        sz += _count_resolved_tags_size(t, child);
    }
    return sz;
}
} // namespace

void Tree::resolve_tags()
{
    if(empty())
        return;
    if(num_tag_directives() == 0)
        return;
    size_t needed_size = _count_resolved_tags_size(this, root_id());
    if(needed_size)
        reserve_arena(arena_size() + needed_size);
    _resolve_tags(this, root_id());
}


//-----------------------------------------------------------------------------

csubstr Tree::lookup_result::resolved() const
{
    csubstr p = path.first(path_pos);
    if(p.ends_with('.'))
        p = p.first(p.len-1);
    return p;
}

csubstr Tree::lookup_result::unresolved() const
{
    return path.sub(path_pos);
}

void Tree::_advance(lookup_result *r, size_t more) const
{
    r->path_pos += more;
    if(r->path.sub(r->path_pos).begins_with('.'))
        ++r->path_pos;
}

Tree::lookup_result Tree::lookup_path(csubstr path, size_t start) const
{
    if(start == NONE)
        start = root_id();
    lookup_result r(path, start);
    if(path.empty())
        return r;
    _lookup_path(&r);
    if(r.target == NONE && r.closest == start)
        r.closest = NONE;
    return r;
}

size_t Tree::lookup_path_or_modify(csubstr default_value, csubstr path, size_t start)
{
    size_t target = _lookup_path_or_create(path, start);
    if(parent_is_map(target))
        to_keyval(target, key(target), default_value);
    else
        to_val(target, default_value);
    return target;
}

size_t Tree::lookup_path_or_modify(Tree const *src, size_t src_node, csubstr path, size_t start)
{
    size_t target = _lookup_path_or_create(path, start);
    merge_with(src, src_node, target);
    return target;
}

size_t Tree::_lookup_path_or_create(csubstr path, size_t start)
{
    if(start == NONE)
        start = root_id();
    lookup_result r(path, start);
    _lookup_path(&r);
    if(r.target != NONE)
    {
        C4_ASSERT(r.unresolved().empty());
        return r.target;
    }
    _lookup_path_modify(&r);
    return r.target;
}

void Tree::_lookup_path(lookup_result *r) const
{
    C4_ASSERT( ! r->unresolved().empty());
    _lookup_path_token parent{"", type(r->closest)};
    size_t node;
    do
    {
        node = _next_node(r, &parent);
        if(node != NONE)
            r->closest = node;
        if(r->unresolved().empty())
        {
            r->target = node;
            return;
        }
    } while(node != NONE);
}

void Tree::_lookup_path_modify(lookup_result *r)
{
    C4_ASSERT( ! r->unresolved().empty());
    _lookup_path_token parent{"", type(r->closest)};
    size_t node;
    do
    {
        node = _next_node_modify(r, &parent);
        if(node != NONE)
            r->closest = node;
        if(r->unresolved().empty())
        {
            r->target = node;
            return;
        }
    } while(node != NONE);
}

size_t Tree::_next_node(lookup_result * r, _lookup_path_token *parent) const
{
    _lookup_path_token token = _next_token(r, *parent);
    if( ! token)
        return NONE;

    size_t node = NONE;
    csubstr prev = token.value;
    if(token.type == MAP || token.type == SEQ)
    {
        _RYML_CB_ASSERT(m_callbacks, !token.value.begins_with('['));
        //_RYML_CB_ASSERT(m_callbacks, is_container(r->closest) || r->closest == NONE);
        _RYML_CB_ASSERT(m_callbacks, is_map(r->closest));
        node = find_child(r->closest, token.value);
    }
    else if(token.type == KEYVAL)
    {
        _RYML_CB_ASSERT(m_callbacks, r->unresolved().empty());
        if(is_map(r->closest))
            node = find_child(r->closest, token.value);
    }
    else if(token.type == KEY)
    {
        _RYML_CB_ASSERT(m_callbacks, token.value.begins_with('[') && token.value.ends_with(']'));
        token.value = token.value.offs(1, 1).trim(' ');
        size_t idx = 0;
        _RYML_CB_CHECK(m_callbacks, from_chars(token.value, &idx));
        node = child(r->closest, idx);
    }
    else
    {
        C4_NEVER_REACH();
    }

    if(node != NONE)
    {
        *parent = token;
    }
    else
    {
        csubstr p = r->path.sub(r->path_pos > 0 ? r->path_pos - 1 : r->path_pos);
        r->path_pos -= prev.len;
        if(p.begins_with('.'))
            r->path_pos -= 1u;
    }

    return node;
}

size_t Tree::_next_node_modify(lookup_result * r, _lookup_path_token *parent)
{
    _lookup_path_token token = _next_token(r, *parent);
    if( ! token)
        return NONE;

    size_t node = NONE;
    if(token.type == MAP || token.type == SEQ)
    {
        _RYML_CB_ASSERT(m_callbacks, !token.value.begins_with('['));
        //_RYML_CB_ASSERT(m_callbacks, is_container(r->closest) || r->closest == NONE);
        if( ! is_container(r->closest))
        {
            if(has_key(r->closest))
                to_map(r->closest, key(r->closest));
            else
                to_map(r->closest);
        }
        else
        {
            if(is_map(r->closest))
                node = find_child(r->closest, token.value);
            else
            {
                size_t pos = NONE;
                _RYML_CB_CHECK(m_callbacks, c4::atox(token.value, &pos));
                _RYML_CB_ASSERT(m_callbacks, pos != NONE);
                node = child(r->closest, pos);
            }
        }
        if(node == NONE)
        {
            _RYML_CB_ASSERT(m_callbacks, is_map(r->closest));
            node = append_child(r->closest);
            NodeData *n = _p(node);
            n->m_key.scalar = token.value;
            n->m_type.add(KEY);
        }
    }
    else if(token.type == KEYVAL)
    {
        _RYML_CB_ASSERT(m_callbacks, r->unresolved().empty());
        if(is_map(r->closest))
        {
            node = find_child(r->closest, token.value);
            if(node == NONE)
                node = append_child(r->closest);
        }
        else
        {
            _RYML_CB_ASSERT(m_callbacks, !is_seq(r->closest));
            _add_flags(r->closest, MAP);
            node = append_child(r->closest);
        }
        NodeData *n = _p(node);
        n->m_key.scalar = token.value;
        n->m_val.scalar = "";
        n->m_type.add(KEYVAL);
    }
    else if(token.type == KEY)
    {
        _RYML_CB_ASSERT(m_callbacks, token.value.begins_with('[') && token.value.ends_with(']'));
        token.value = token.value.offs(1, 1).trim(' ');
        size_t idx;
        if( ! from_chars(token.value, &idx))
             return NONE;
        if( ! is_container(r->closest))
        {
            if(has_key(r->closest))
            {
                csubstr k = key(r->closest);
                _clear_type(r->closest);
                to_seq(r->closest, k);
            }
            else
            {
                _clear_type(r->closest);
                to_seq(r->closest);
            }
        }
        _RYML_CB_ASSERT(m_callbacks, is_container(r->closest));
        node = child(r->closest, idx);
        if(node == NONE)
        {
            _RYML_CB_ASSERT(m_callbacks, num_children(r->closest) <= idx);
            for(size_t i = num_children(r->closest); i <= idx; ++i)
            {
                node = append_child(r->closest);
                if(i < idx)
                {
                    if(is_map(r->closest))
                        to_keyval(node, /*"~"*/{}, /*"~"*/{});
                    else if(is_seq(r->closest))
                        to_val(node, /*"~"*/{});
                }
            }
        }
    }
    else
    {
        C4_NEVER_REACH();
    }

    _RYML_CB_ASSERT(m_callbacks, node != NONE);
    *parent = token;
    return node;
}

/** types of tokens:
 * - seeing "map."  ---> "map"/MAP
 * - finishing "scalar" ---> "scalar"/KEYVAL
 * - seeing "seq[n]" ---> "seq"/SEQ (--> "[n]"/KEY)
 * - seeing "[n]" ---> "[n]"/KEY
 */
Tree::_lookup_path_token Tree::_next_token(lookup_result *r, _lookup_path_token const& parent) const
{
    csubstr unres = r->unresolved();
    if(unres.empty())
        return {};

    // is it an indexation like [0], [1], etc?
    if(unres.begins_with('['))
    {
        size_t pos = unres.find(']');
        if(pos == csubstr::npos)
            return {};
        csubstr idx = unres.first(pos + 1);
        _advance(r, pos + 1);
        return {idx, KEY};
    }

    // no. so it must be a name
    size_t pos = unres.first_of(".[");
    if(pos == csubstr::npos)
    {
        _advance(r, unres.len);
        NodeType t;
        if(( ! parent) || parent.type.is_seq())
            return {unres, VAL};
        return {unres, KEYVAL};
    }

    // it's either a map or a seq
    _RYML_CB_ASSERT(m_callbacks, unres[pos] == '.' || unres[pos] == '[');
    if(unres[pos] == '.')
    {
        _RYML_CB_ASSERT(m_callbacks, pos != 0);
        _advance(r, pos + 1);
        return {unres.first(pos), MAP};
    }

    _RYML_CB_ASSERT(m_callbacks, unres[pos] == '[');
    _advance(r, pos);
    return {unres.first(pos), SEQ};
}


} // namespace ryml
} // namespace c4


C4_SUPPRESS_WARNING_GCC_POP
C4_SUPPRESS_WARNING_MSVC_POP

#endif /* RYML_SINGLE_HDR_DEFINE_NOW */


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/tree.cpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/parse.cpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/parse.cpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifdef RYML_SINGLE_HDR_DEFINE_NOW
// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/parse.hpp
//#include "c4/yml/parse.hpp"
#if !defined(C4_YML_PARSE_HPP_) && !defined(_C4_YML_PARSE_HPP_)
#error "amalgamate: file c4/yml/parse.hpp must have been included at this point"
#endif /* C4_YML_PARSE_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/error.hpp
//#include "c4/error.hpp"
#if !defined(C4_ERROR_HPP_) && !defined(_C4_ERROR_HPP_)
#error "amalgamate: file c4/error.hpp must have been included at this point"
#endif /* C4_ERROR_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/utf.hpp
//#include "c4/utf.hpp"
#if !defined(C4_UTF_HPP_) && !defined(_C4_UTF_HPP_)
#error "amalgamate: file c4/utf.hpp must have been included at this point"
#endif /* C4_UTF_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/dump.hpp
//#include <c4/dump.hpp>
#if !defined(C4_DUMP_HPP_) && !defined(_C4_DUMP_HPP_)
#error "amalgamate: file c4/dump.hpp must have been included at this point"
#endif /* C4_DUMP_HPP_ */


//included above:
//#include <ctype.h>
//included above:
//#include <stdarg.h>
//included above:
//#include <stdio.h>

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/detail/parser_dbg.hpp
//#include "c4/yml/detail/parser_dbg.hpp"
#if !defined(C4_YML_DETAIL_PARSER_DBG_HPP_) && !defined(_C4_YML_DETAIL_PARSER_DBG_HPP_)
#error "amalgamate: file c4/yml/detail/parser_dbg.hpp must have been included at this point"
#endif /* C4_YML_DETAIL_PARSER_DBG_HPP_ */

#ifdef RYML_DBG
// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/detail/print.hpp
//#include "c4/yml/detail/print.hpp"
#if !defined(C4_YML_DETAIL_PRINT_HPP_) && !defined(_C4_YML_DETAIL_PRINT_HPP_)
#error "amalgamate: file c4/yml/detail/print.hpp must have been included at this point"
#endif /* C4_YML_DETAIL_PRINT_HPP_ */

#endif

#ifndef RYML_ERRMSG_SIZE
    #define RYML_ERRMSG_SIZE 1024
#endif

//#define RYML_WITH_TAB_TOKENS
#ifdef RYML_WITH_TAB_TOKENS
#define _RYML_WITH_TAB_TOKENS(...) __VA_ARGS__
#define _RYML_WITH_OR_WITHOUT_TAB_TOKENS(with, without) with
#else
#define _RYML_WITH_TAB_TOKENS(...)
#define _RYML_WITH_OR_WITHOUT_TAB_TOKENS(with, without) without
#endif


#if defined(_MSC_VER)
#   pragma warning(push)
#   pragma warning(disable: 4296/*expression is always 'boolean_value'*/)
#elif defined(__clang__)
#   pragma clang diagnostic push
#   pragma clang diagnostic ignored "-Wtype-limits" // to remove a warning on an assertion that a size_t >= 0. Later on, this size_t will turn into a template argument, and then it can become < 0.
#   pragma clang diagnostic ignored "-Wformat-nonliteral"
#elif defined(__GNUC__)
#   pragma GCC diagnostic push
#   pragma GCC diagnostic ignored "-Wtype-limits" // to remove a warning on an assertion that a size_t >= 0. Later on, this size_t will turn into a template argument, and then it can become < 0.
#   pragma GCC diagnostic ignored "-Wformat-nonliteral"
#   if __GNUC__ >= 7
#       pragma GCC diagnostic ignored "-Wduplicated-branches"
#   endif
#endif

namespace c4 {
namespace yml {

namespace {

template<class DumpFn, class ...Args>
void _parse_dump(DumpFn dumpfn, c4::csubstr fmt, Args&& ...args)
{
    char writebuf[256];
    auto results = c4::format_dump_resume(dumpfn, writebuf, fmt, std::forward<Args>(args)...);
    // resume writing if the results failed to fit the buffer
    if(C4_UNLIKELY(results.bufsize > sizeof(writebuf))) // bufsize will be that of the largest element serialized. Eg int(1), will require 1 byte.
    {
        results = format_dump_resume(dumpfn, results, writebuf, fmt, std::forward<Args>(args)...);
        if(C4_UNLIKELY(results.bufsize > sizeof(writebuf)))
        {
            results = format_dump_resume(dumpfn, results, writebuf, fmt, std::forward<Args>(args)...);
        }
    }
}

bool _is_scalar_next__runk(csubstr s)
{
    return !(s.begins_with(": ") || s.begins_with_any("#,{}[]%&") || s.begins_with("? ") || s == "-" || s.begins_with("- ") || s.begins_with(":\"") || s.begins_with(":'"));
}

bool _is_scalar_next__rseq_rval(csubstr s)
{
    return !(s.begins_with_any("[{!&") || s.begins_with("? ") || s.begins_with("- ") || s == "-");
}

bool _is_scalar_next__rmap(csubstr s)
{
    return !(s.begins_with(": ") || s.begins_with_any("#,!&") || s.begins_with("? ") _RYML_WITH_TAB_TOKENS(|| s.begins_with(":\t")));
}

bool _is_scalar_next__rmap_val(csubstr s)
{
    return !(s.begins_with("- ") || s.begins_with_any("{[") || s == "-");
}

bool _is_doc_sep(csubstr s)
{
    constexpr const csubstr dashes = "---";
    constexpr const csubstr ellipsis = "...";
    constexpr const csubstr whitesp = " \t";
    if(s.begins_with(dashes))
        return s == dashes || s.sub(3).begins_with_any(whitesp);
    else if(s.begins_with(ellipsis))
        return s == ellipsis || s.sub(3).begins_with_any(whitesp);
    return false;
}

/** @p i is set to the first non whitespace character after the line
 * @return the number of empty lines after the initial position */
size_t count_following_newlines(csubstr r, size_t *C4_RESTRICT i, size_t indentation)
{
    RYML_ASSERT(r[*i] == '\n');
    size_t numnl_following = 0;
    ++(*i);
    for( ; *i < r.len; ++(*i))
    {
        if(r.str[*i] == '\n')
        {
            ++numnl_following;
            if(indentation) // skip the indentation after the newline
            {
                size_t stop = *i + indentation;
                for( ; *i < r.len; ++(*i))
                {
                    if(r.str[*i] != ' ' && r.str[*i] != '\r')
                        break;
                    RYML_ASSERT(*i < stop);
                }
                C4_UNUSED(stop);
            }
        }
        else if(r.str[*i] == ' ' || r.str[*i] == '\t' || r.str[*i] == '\r')  // skip leading whitespace
            ;
        else
            break;
    }
    return numnl_following;
}

} // anon namespace


//-----------------------------------------------------------------------------

Parser::~Parser()
{
    _free();
    _clr();
}

Parser::Parser(Callbacks const& cb, ParserOptions opts)
    : m_options(opts)
    , m_file()
    , m_buf()
    , m_root_id(NONE)
    , m_tree()
    , m_stack(cb)
    , m_state()
    , m_key_tag_indentation(0)
    , m_key_tag2_indentation(0)
    , m_key_tag()
    , m_key_tag2()
    , m_val_tag_indentation(0)
    , m_val_tag()
    , m_key_anchor_was_before(false)
    , m_key_anchor_indentation(0)
    , m_key_anchor()
    , m_val_anchor_indentation(0)
    , m_val_anchor()
    , m_filter_arena()
    , m_newline_offsets()
    , m_newline_offsets_size(0)
    , m_newline_offsets_capacity(0)
    , m_newline_offsets_buf()
{
    m_stack.push(State{});
    m_state = &m_stack.top();
}

Parser::Parser(Parser &&that)
    : m_options(that.m_options)
    , m_file(that.m_file)
    , m_buf(that.m_buf)
    , m_root_id(that.m_root_id)
    , m_tree(that.m_tree)
    , m_stack(std::move(that.m_stack))
    , m_state(&m_stack.top())
    , m_key_tag_indentation(that.m_key_tag_indentation)
    , m_key_tag2_indentation(that.m_key_tag2_indentation)
    , m_key_tag(that.m_key_tag)
    , m_key_tag2(that.m_key_tag2)
    , m_val_tag_indentation(that.m_val_tag_indentation)
    , m_val_tag(that.m_val_tag)
    , m_key_anchor_was_before(that.m_key_anchor_was_before)
    , m_key_anchor_indentation(that.m_key_anchor_indentation)
    , m_key_anchor(that.m_key_anchor)
    , m_val_anchor_indentation(that.m_val_anchor_indentation)
    , m_val_anchor(that.m_val_anchor)
    , m_filter_arena(that.m_filter_arena)
    , m_newline_offsets(that.m_newline_offsets)
    , m_newline_offsets_size(that.m_newline_offsets_size)
    , m_newline_offsets_capacity(that.m_newline_offsets_capacity)
    , m_newline_offsets_buf(that.m_newline_offsets_buf)
{
    that._clr();
}

Parser::Parser(Parser const& that)
    : m_options(that.m_options)
    , m_file(that.m_file)
    , m_buf(that.m_buf)
    , m_root_id(that.m_root_id)
    , m_tree(that.m_tree)
    , m_stack(that.m_stack)
    , m_state(&m_stack.top())
    , m_key_tag_indentation(that.m_key_tag_indentation)
    , m_key_tag2_indentation(that.m_key_tag2_indentation)
    , m_key_tag(that.m_key_tag)
    , m_key_tag2(that.m_key_tag2)
    , m_val_tag_indentation(that.m_val_tag_indentation)
    , m_val_tag(that.m_val_tag)
    , m_key_anchor_was_before(that.m_key_anchor_was_before)
    , m_key_anchor_indentation(that.m_key_anchor_indentation)
    , m_key_anchor(that.m_key_anchor)
    , m_val_anchor_indentation(that.m_val_anchor_indentation)
    , m_val_anchor(that.m_val_anchor)
    , m_filter_arena()
    , m_newline_offsets()
    , m_newline_offsets_size()
    , m_newline_offsets_capacity()
    , m_newline_offsets_buf()
{
    if(that.m_newline_offsets_capacity)
    {
        _resize_locations(that.m_newline_offsets_capacity);
        _RYML_CB_CHECK(m_stack.m_callbacks, m_newline_offsets_capacity == that.m_newline_offsets_capacity);
        memcpy(m_newline_offsets, that.m_newline_offsets, that.m_newline_offsets_size * sizeof(size_t));
        m_newline_offsets_size = that.m_newline_offsets_size;
    }
    if(that.m_filter_arena.len)
    {
        _resize_filter_arena(that.m_filter_arena.len);
    }
}

Parser& Parser::operator=(Parser &&that)
{
    _free();
    m_options = (that.m_options);
    m_file = (that.m_file);
    m_buf = (that.m_buf);
    m_root_id = (that.m_root_id);
    m_tree = (that.m_tree);
    m_stack = std::move(that.m_stack);
    m_state = (&m_stack.top());
    m_key_tag_indentation = (that.m_key_tag_indentation);
    m_key_tag2_indentation = (that.m_key_tag2_indentation);
    m_key_tag = (that.m_key_tag);
    m_key_tag2 = (that.m_key_tag2);
    m_val_tag_indentation = (that.m_val_tag_indentation);
    m_val_tag = (that.m_val_tag);
    m_key_anchor_was_before = (that.m_key_anchor_was_before);
    m_key_anchor_indentation = (that.m_key_anchor_indentation);
    m_key_anchor = (that.m_key_anchor);
    m_val_anchor_indentation = (that.m_val_anchor_indentation);
    m_val_anchor = (that.m_val_anchor);
    m_filter_arena = that.m_filter_arena;
    m_newline_offsets = (that.m_newline_offsets);
    m_newline_offsets_size = (that.m_newline_offsets_size);
    m_newline_offsets_capacity = (that.m_newline_offsets_capacity);
    m_newline_offsets_buf = (that.m_newline_offsets_buf);
    that._clr();
    return *this;
}

Parser& Parser::operator=(Parser const& that)
{
    _free();
    m_options = (that.m_options);
    m_file = (that.m_file);
    m_buf = (that.m_buf);
    m_root_id = (that.m_root_id);
    m_tree = (that.m_tree);
    m_stack = that.m_stack;
    m_state = &m_stack.top();
    m_key_tag_indentation = (that.m_key_tag_indentation);
    m_key_tag2_indentation = (that.m_key_tag2_indentation);
    m_key_tag = (that.m_key_tag);
    m_key_tag2 = (that.m_key_tag2);
    m_val_tag_indentation = (that.m_val_tag_indentation);
    m_val_tag = (that.m_val_tag);
    m_key_anchor_was_before = (that.m_key_anchor_was_before);
    m_key_anchor_indentation = (that.m_key_anchor_indentation);
    m_key_anchor = (that.m_key_anchor);
    m_val_anchor_indentation = (that.m_val_anchor_indentation);
    m_val_anchor = (that.m_val_anchor);
    if(that.m_filter_arena.len > 0)
        _resize_filter_arena(that.m_filter_arena.len);
    if(that.m_newline_offsets_capacity > m_newline_offsets_capacity)
        _resize_locations(that.m_newline_offsets_capacity);
    _RYML_CB_CHECK(m_stack.m_callbacks, m_newline_offsets_capacity >= that.m_newline_offsets_capacity);
    _RYML_CB_CHECK(m_stack.m_callbacks, m_newline_offsets_capacity >= that.m_newline_offsets_size);
    memcpy(m_newline_offsets, that.m_newline_offsets, that.m_newline_offsets_size * sizeof(size_t));
    m_newline_offsets_size = that.m_newline_offsets_size;
    m_newline_offsets_buf = that.m_newline_offsets_buf;
    return *this;
}

void Parser::_clr()
{
    m_options = {};
    m_file = {};
    m_buf = {};
    m_root_id = {};
    m_tree = {};
    m_stack.clear();
    m_state = {};
    m_key_tag_indentation = {};
    m_key_tag2_indentation = {};
    m_key_tag = {};
    m_key_tag2 = {};
    m_val_tag_indentation = {};
    m_val_tag = {};
    m_key_anchor_was_before = {};
    m_key_anchor_indentation = {};
    m_key_anchor = {};
    m_val_anchor_indentation = {};
    m_val_anchor = {};
    m_filter_arena = {};
    m_newline_offsets = {};
    m_newline_offsets_size = {};
    m_newline_offsets_capacity = {};
    m_newline_offsets_buf = {};
}

void Parser::_free()
{
    if(m_newline_offsets)
    {
        _RYML_CB_FREE(m_stack.m_callbacks, m_newline_offsets, size_t, m_newline_offsets_capacity);
        m_newline_offsets = nullptr;
        m_newline_offsets_size = 0u;
        m_newline_offsets_capacity = 0u;
        m_newline_offsets_buf = 0u;
    }
    if(m_filter_arena.len)
    {
        _RYML_CB_FREE(m_stack.m_callbacks, m_filter_arena.str, char, m_filter_arena.len);
        m_filter_arena = {};
    }
    m_stack._free();
}


//-----------------------------------------------------------------------------
void Parser::_reset()
{
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_stack.size() == 1);
    m_stack.clear();
    m_stack.push({});
    m_state = &m_stack.top();
    m_state->reset(m_file.str, m_root_id);

    m_key_tag_indentation = 0;
    m_key_tag2_indentation = 0;
    m_key_tag.clear();
    m_key_tag2.clear();
    m_val_tag_indentation = 0;
    m_val_tag.clear();
    m_key_anchor_was_before = false;
    m_key_anchor_indentation = 0;
    m_key_anchor.clear();
    m_val_anchor_indentation = 0;
    m_val_anchor.clear();

    if(m_options.locations())
    {
        _prepare_locations();
    }
}

//-----------------------------------------------------------------------------
template<class DumpFn>
void Parser::_fmt_msg(DumpFn &&dumpfn) const
{
    auto const& lc = m_state->line_contents;
    csubstr contents = lc.stripped;
    if(contents.len)
    {
        // print the yaml src line
        size_t offs = 3u + to_chars(substr{}, m_state->pos.line) + to_chars(substr{}, m_state->pos.col);
        if(m_file.len)
        {
            _parse_dump(dumpfn, "{}:", m_file);
            offs += m_file.len + 1;
        }
        _parse_dump(dumpfn, "{}:{}: ", m_state->pos.line, m_state->pos.col);
        csubstr maybe_full_content = (contents.len < 80u ? contents : contents.first(80u));
        csubstr maybe_ellipsis = (contents.len < 80u ? csubstr{} : csubstr("..."));
        _parse_dump(dumpfn, "{}{}  (size={})\n", maybe_full_content, maybe_ellipsis, contents.len);
        // highlight the remaining portion of the previous line
        size_t firstcol = (size_t)(lc.rem.begin() - lc.full.begin());
        size_t lastcol = firstcol + lc.rem.len;
        for(size_t i = 0; i < offs + firstcol; ++i)
            dumpfn(" ");
        dumpfn("^");
        for(size_t i = 1, e = (lc.rem.len < 80u ? lc.rem.len : 80u); i < e; ++i)
            dumpfn("~");
        _parse_dump(dumpfn, "{}  (cols {}-{})\n", maybe_ellipsis, firstcol+1, lastcol+1);
    }
    else
    {
        dumpfn("\n");
    }

#ifdef RYML_DBG
    // next line: print the state flags
    {
        char flagbuf_[64];
        _parse_dump(dumpfn, "top state: {}\n", _prfl(flagbuf_, m_state->flags));
    }
#endif
}


//-----------------------------------------------------------------------------
template<class ...Args>
void Parser::_err(csubstr fmt, Args const& C4_RESTRICT ...args) const
{
    char errmsg[RYML_ERRMSG_SIZE];
    detail::_SubstrWriter writer(errmsg);
    auto dumpfn = [&writer](csubstr s){ writer.append(s); };
    _parse_dump(dumpfn, fmt, args...);
    writer.append('\n');
    _fmt_msg(dumpfn);
    size_t len = writer.pos < RYML_ERRMSG_SIZE ? writer.pos : RYML_ERRMSG_SIZE;
    m_tree->m_callbacks.m_error(errmsg, len, m_state->pos, m_tree->m_callbacks.m_user_data);
}

//-----------------------------------------------------------------------------
#ifdef RYML_DBG
template<class ...Args>
void Parser::_dbg(csubstr fmt, Args const& C4_RESTRICT ...args) const
{
    auto dumpfn = [](csubstr s){ fwrite(s.str, 1, s.len, stdout); };
    _parse_dump(dumpfn, fmt, args...);
    dumpfn("\n");
    _fmt_msg(dumpfn);
}
#endif

//-----------------------------------------------------------------------------
bool Parser::_finished_file() const
{
    bool ret = m_state->pos.offset >= m_buf.len;
    if(ret)
    {
        _c4dbgp("finished file!!!");
    }
    return ret;
}

//-----------------------------------------------------------------------------
bool Parser::_finished_line() const
{
    return m_state->line_contents.rem.empty();
}

//-----------------------------------------------------------------------------
void Parser::parse_in_place(csubstr file, substr buf, Tree *t, size_t node_id)
{
    m_file = file;
    m_buf = buf;
    m_root_id = node_id;
    m_tree = t;
    _reset();
    while( ! _finished_file())
    {
        _scan_line();
        while( ! _finished_line())
            _handle_line();
        if(_finished_file())
            break; // it may have finished because of multiline blocks
        _line_ended();
    }
    _handle_finished_file();
}

//-----------------------------------------------------------------------------
void Parser::_handle_finished_file()
{
    _end_stream();
}

//-----------------------------------------------------------------------------
void Parser::_handle_line()
{
    _c4dbgq("\n-----------");
    _c4dbgt("handling line={}, offset={}B", m_state->pos.line, m_state->pos.offset);
    _RYML_CB_ASSERT(m_stack.m_callbacks,  ! m_state->line_contents.rem.empty());
    if(has_any(RSEQ))
    {
        if(has_any(FLOW))
        {
            if(_handle_seq_flow())
                return;
        }
        else
        {
            if(_handle_seq_blck())
                return;
        }
    }
    else if(has_any(RMAP))
    {
        if(has_any(FLOW))
        {
            if(_handle_map_flow())
                return;
        }
        else
        {
            if(_handle_map_blck())
                return;
        }
    }
    else if(has_any(RUNK))
    {
        if(_handle_unk())
            return;
    }

    if(_handle_top())
        return;
}


//-----------------------------------------------------------------------------
bool Parser::_handle_unk()
{
    _c4dbgp("handle_unk");

    csubstr rem = m_state->line_contents.rem;
    const bool start_as_child = (node(m_state) == nullptr);

    if(C4_UNLIKELY(has_any(NDOC)))
    {
        if(rem == "---" || rem.begins_with("--- "))
        {
            _start_new_doc(rem);
            return true;
        }
        auto trimmed = rem.triml(' ');
        if(trimmed == "---" || trimmed.begins_with("--- "))
        {
            _RYML_CB_ASSERT(m_stack.m_callbacks, rem.len >= trimmed.len);
            _line_progressed(rem.len - trimmed.len);
            _start_new_doc(trimmed);
            _save_indentation();
            return true;
        }
        else if(trimmed.begins_with("..."))
        {
            _end_stream();
        }
        else if(trimmed.first_of("#%") == csubstr::npos) // neither a doc nor a tag
        {
            _c4dbgpf("starting implicit doc to accomodate unexpected tokens: '{}'", rem);
            size_t indref = m_state->indref;
            _push_level();
            _start_doc();
            _set_indentation(indref);
        }
        _RYML_CB_ASSERT(m_stack.m_callbacks, !trimmed.empty());
    }

    _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RNXT|RSEQ|RMAP));
    if(m_state->indref > 0)
    {
        csubstr ws = rem.left_of(rem.first_not_of(' '));
        if(m_state->indref <= ws.len)
        {
            _c4dbgpf("skipping base indentation of {}", m_state->indref);
            _line_progressed(m_state->indref);
            rem = rem.sub(m_state->indref);
        }
    }

    if(rem.begins_with("- ") _RYML_WITH_TAB_TOKENS( || rem.begins_with("-\t")))
    {
        _c4dbgpf("it's a seq (as_child={})", start_as_child);
        _move_key_anchor_to_val_anchor();
        _move_key_tag_to_val_tag();
        _push_level();
        _start_seq(start_as_child);
        _save_indentation();
        _line_progressed(2);
        return true;
    }
    else if(rem == '-')
    {
        _c4dbgpf("it's a seq (as_child={})", start_as_child);
        _move_key_anchor_to_val_anchor();
        _move_key_tag_to_val_tag();
        _push_level();
        _start_seq(start_as_child);
        _save_indentation();
        _line_progressed(1);
        return true;
    }
    else if(rem.begins_with('['))
    {
        _c4dbgpf("it's a seq, flow (as_child={})", start_as_child);
        _move_key_anchor_to_val_anchor();
        _move_key_tag_to_val_tag();
        _push_level(/*explicit flow*/true);
        _start_seq(start_as_child);
        add_flags(FLOW);
        _line_progressed(1);
        return true;
    }
    else if(rem.begins_with('{'))
    {
        _c4dbgpf("it's a map, flow (as_child={})", start_as_child);
        _move_key_anchor_to_val_anchor();
        _move_key_tag_to_val_tag();
        _push_level(/*explicit flow*/true);
        _start_map(start_as_child);
        addrem_flags(FLOW|RKEY, RVAL);
        _line_progressed(1);
        return true;
    }
    else if(rem.begins_with("? "))
    {
        _c4dbgpf("it's a map (as_child={}) + this key is complex", start_as_child);
        _move_key_anchor_to_val_anchor();
        _move_key_tag_to_val_tag();
        _push_level();
        _start_map(start_as_child);
        addrem_flags(RKEY|QMRK, RVAL);
        _save_indentation();
        _line_progressed(2);
        return true;
    }
    else if(rem.begins_with(": ") && !has_all(SSCL))
    {
        _c4dbgp("it's a map with an empty key");
        _move_key_anchor_to_val_anchor();
        _move_key_tag_to_val_tag();
        _push_level();
        _start_map(start_as_child);
        _store_scalar_null(rem.str);
        addrem_flags(RVAL, RKEY);
        _save_indentation();
        _line_progressed(2);
        return true;
    }
    else if(rem == ':' && !has_all(SSCL))
    {
        _c4dbgp("it's a map with an empty key");
        _move_key_anchor_to_val_anchor();
        _move_key_tag_to_val_tag();
        _push_level();
        _start_map(start_as_child);
        _store_scalar_null(rem.str);
        addrem_flags(RVAL, RKEY);
        _save_indentation();
        _line_progressed(1);
        return true;
    }
    else if(_handle_types())
    {
        return true;
    }
    else if(!rem.begins_with('*') && _handle_key_anchors_and_refs())
    {
        return true;
    }
    else if(has_all(SSCL))
    {
        _c4dbgpf("there's a stored scalar: '{}'", m_state->scalar);

        csubstr saved_scalar;
        bool is_quoted;
        if(_scan_scalar_unk(&saved_scalar, &is_quoted))
        {
            rem = m_state->line_contents.rem;
            _c4dbgpf("... and there's also a scalar next! '{}'", saved_scalar);
            if(rem.begins_with_any(" \t"))
            {
                size_t n = rem.first_not_of(" \t");
                _c4dbgpf("skipping {} spaces/tabs", n);
                rem = rem.sub(n);
                _line_progressed(n);
            }
        }

        _c4dbgpf("rem='{}'", rem);

        if(rem.begins_with(", "))
        {
            _c4dbgpf("got a ',' -- it's a seq (as_child={})", start_as_child);
            _start_seq(start_as_child);
            add_flags(FLOW);
            _append_val(_consume_scalar());
            _line_progressed(2);
        }
        else if(rem.begins_with(','))
        {
            _c4dbgpf("got a ',' -- it's a seq (as_child={})", start_as_child);
            _start_seq(start_as_child);
            add_flags(FLOW);
            _append_val(_consume_scalar());
            _line_progressed(1);
        }
        else if(rem.begins_with(": ") _RYML_WITH_TAB_TOKENS( || rem.begins_with(":\t")))
        {
            _c4dbgpf("got a ': ' -- it's a map (as_child={})", start_as_child);
            _start_map_unk(start_as_child); // wait for the val scalar to append the key-val pair
            _line_progressed(2);
        }
        else if(rem == ":" || rem.begins_with(":\"") || rem.begins_with(":'"))
        {
            if(rem == ":") { _c4dbgpf("got a ':' -- it's a map (as_child={})", start_as_child); }
            else { _c4dbgpf("got a '{}' -- it's a map (as_child={})", rem.first(2), start_as_child); }
            _start_map_unk(start_as_child); // wait for the val scalar to append the key-val pair
            _line_progressed(1); // advance only 1
        }
        else if(rem.begins_with('}'))
        {
            if(!has_all(RMAP|FLOW))
            {
                _c4err("invalid token: not reading a map");
            }
            if(!has_all(SSCL))
            {
                _c4err("no scalar stored");
            }
            _append_key_val(saved_scalar);
            _stop_map();
            _line_progressed(1);
        }
        else if(rem.begins_with("..."))
        {
            _c4dbgp("got stream end '...'");
            _end_stream();
            _line_progressed(3);
        }
        else if(rem.begins_with('#'))
        {
            _c4dbgpf("it's a comment: '{}'", rem);
            _scan_comment();
            return true;
        }
        else if(_handle_key_anchors_and_refs())
        {
            return true;
        }
        else if(rem.begins_with(" ") || rem.begins_with("\t"))
        {
            size_t n = rem.first_not_of(" \t");
            if(n == npos)
                n = rem.len;
            _c4dbgpf("has {} spaces/tabs, skip...", n);
            _line_progressed(n);
            return true;
        }
        else if(rem.empty())
        {
            // nothing to do
        }
        else if(rem == "---" || rem.begins_with("--- "))
        {
            _c4dbgp("caught ---: starting doc");
            _start_new_doc(rem);
            return true;
        }
        else if(rem.begins_with('%'))
        {
            _c4dbgp("caught a directive: ignoring...");
            _line_progressed(rem.len);
            return true;
        }
        else
        {
            _c4err("parse error");
        }

        if( ! saved_scalar.empty())
        {
            _store_scalar(saved_scalar, is_quoted);
        }

        return true;
    }
    else
    {
        _RYML_CB_ASSERT(m_stack.m_callbacks,  ! has_any(SSCL));
        csubstr scalar;
        size_t indentation = m_state->line_contents.indentation; // save
        bool is_quoted;
        if(_scan_scalar_unk(&scalar, &is_quoted))
        {
            _c4dbgpf("got a {} scalar", is_quoted ? "quoted" : "");
            rem = m_state->line_contents.rem;
            {
                size_t first = rem.first_not_of(" \t");
                if(first && first != npos)
                {
                    _c4dbgpf("skip {} whitespace characters", first);
                   _line_progressed(first);
                   rem = rem.sub(first);
                }
            }
            _store_scalar(scalar, is_quoted);
            if(rem.begins_with(": ") _RYML_WITH_TAB_TOKENS( || rem.begins_with(":\t")))
            {
                _c4dbgpf("got a ': ' next -- it's a map (as_child={})", start_as_child);
                _push_level();
                _start_map(start_as_child); // wait for the val scalar to append the key-val pair
                _set_indentation(indentation);
                _line_progressed(2); // call this AFTER saving the indentation
            }
            else if(rem == ":")
            {
                _c4dbgpf("got a ':' next -- it's a map (as_child={})", start_as_child);
                _push_level();
                _start_map(start_as_child); // wait for the val scalar to append the key-val pair
                _set_indentation(indentation);
                _line_progressed(1); // call this AFTER saving the indentation
            }
            else
            {
                // we still don't know whether it's a seq or a map
                // so just store the scalar
            }
            return true;
        }
        else if(rem.begins_with_any(" \t"))
        {
            csubstr ws = rem.left_of(rem.first_not_of(" \t"));
            rem = rem.right_of(ws);
            if(has_all(RTOP) && rem.begins_with("---"))
            {
                _c4dbgp("there's a doc starting, and it's indented");
                _set_indentation(ws.len);
            }
            _c4dbgpf("skipping {} spaces/tabs", ws.len);
            _line_progressed(ws.len);
            return true;
        }
    }

    return false;
}


//-----------------------------------------------------------------------------
C4_ALWAYS_INLINE void Parser::_skipchars(char c)
{
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_state->line_contents.rem.begins_with(c));
    size_t pos = m_state->line_contents.rem.first_not_of(c);
    if(pos == npos)
        pos = m_state->line_contents.rem.len; // maybe the line is just whitespace
    _c4dbgpf("skip {} '{}'", pos, c);
    _line_progressed(pos);
}

template<size_t N>
C4_ALWAYS_INLINE void Parser::_skipchars(const char (&chars)[N])
{
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_state->line_contents.rem.begins_with_any(chars));
    size_t pos = m_state->line_contents.rem.first_not_of(chars);
    if(pos == npos)
        pos = m_state->line_contents.rem.len; // maybe the line is just whitespace
    _c4dbgpf("skip {} characters", pos);
    _line_progressed(pos);
}


//-----------------------------------------------------------------------------
bool Parser::_handle_seq_flow()
{
    _c4dbgpf("handle_seq_flow: node_id={} level={}", m_state->node_id, m_state->level);
    csubstr rem = m_state->line_contents.rem;

    _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RKEY));
    _RYML_CB_ASSERT(m_stack.m_callbacks, has_all(RSEQ|FLOW));

    if(rem.begins_with(' '))
    {
        // with explicit flow, indentation does not matter
        _c4dbgp("starts with spaces");
        _skipchars(' ');
        return true;
    }
    _RYML_WITH_TAB_TOKENS(else if(rem.begins_with('\t'))
    {
        _c4dbgp("starts with tabs");
        _skipchars('\t');
        return true;
    })
    else if(rem.begins_with('#'))
    {
        _c4dbgp("it's a comment");
        rem = _scan_comment(); // also progresses the line
        return true;
    }
    else if(rem.begins_with(']'))
    {
        _c4dbgp("end the sequence");
        _pop_level();
        _line_progressed(1);
        if(has_all(RSEQIMAP))
        {
            _stop_seqimap();
            _pop_level();
        }
        return true;
    }

    if(has_any(RVAL))
    {
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RNXT));
        bool is_quoted;
        if(_scan_scalar_seq_flow(&rem, &is_quoted))
        {
            _c4dbgp("it's a scalar");
            addrem_flags(RNXT, RVAL);
            _append_val(rem, is_quoted);
            return true;
        }
        else if(rem.begins_with('['))
        {
            _c4dbgp("val is a child seq");
            addrem_flags(RNXT, RVAL); // before _push_level!
            _push_level(/*explicit flow*/true);
            _start_seq();
            add_flags(FLOW);
            _line_progressed(1);
            return true;
        }
        else if(rem.begins_with('{'))
        {
            _c4dbgp("val is a child map");
            addrem_flags(RNXT, RVAL); // before _push_level!
            _push_level(/*explicit flow*/true);
            _start_map();
            addrem_flags(FLOW|RKEY, RVAL);
            _line_progressed(1);
            return true;
        }
        else if(rem == ':')
        {
            _c4dbgpf("found ':' -- there's an implicit map in the seq node[{}]", m_state->node_id);
            _start_seqimap();
            _line_progressed(1);
            return true;
        }
        else if(rem.begins_with(": ") _RYML_WITH_TAB_TOKENS( || rem.begins_with(":\t")))
        {
            _c4dbgpf("found ': ' -- there's an implicit map in the seq node[{}]", m_state->node_id);
            _start_seqimap();
            _line_progressed(2);
            return true;
        }
        else if(rem.begins_with("? "))
        {
            _c4dbgpf("found '? ' -- there's an implicit map in the seq node[{}]", m_state->node_id);
            _start_seqimap();
            _line_progressed(2);
            _RYML_CB_ASSERT(m_stack.m_callbacks, has_any(SSCL) && m_state->scalar == "");
            addrem_flags(QMRK|RKEY, RVAL|SSCL);
            return true;
        }
        else if(_handle_types())
        {
            return true;
        }
        else if(_handle_val_anchors_and_refs())
        {
            return true;
        }
        else if(rem.begins_with(", "))
        {
            _c4dbgp("found ',' -- the value was null");
            _append_val_null(rem.str - 1);
            _line_progressed(2);
            return true;
        }
        else if(rem.begins_with(','))
        {
            _c4dbgp("found ',' -- the value was null");
            _append_val_null(rem.str - 1);
            _line_progressed(1);
            return true;
        }
        else if(rem.begins_with('\t'))
        {
            _skipchars('\t');
            return true;
        }
        else
        {
            _c4err("parse error");
        }
    }
    else if(has_any(RNXT))
    {
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RVAL));
        if(rem.begins_with(", "))
        {
            _RYML_CB_ASSERT(m_stack.m_callbacks, has_all(FLOW));
            _c4dbgp("seq: expect next val");
            addrem_flags(RVAL, RNXT);
            _line_progressed(2);
            return true;
        }
        else if(rem.begins_with(','))
        {
            _RYML_CB_ASSERT(m_stack.m_callbacks, has_all(FLOW));
            _c4dbgp("seq: expect next val");
            addrem_flags(RVAL, RNXT);
            _line_progressed(1);
            return true;
        }
        else if(rem == ':')
        {
            _c4dbgpf("found ':' -- there's an implicit map in the seq node[{}]", m_state->node_id);
            _start_seqimap();
            _line_progressed(1);
            return true;
        }
        else if(rem.begins_with(": ") _RYML_WITH_TAB_TOKENS( || rem.begins_with(":\t")))
        {
            _c4dbgpf("found ': ' -- there's an implicit map in the seq node[{}]", m_state->node_id);
            _start_seqimap();
            _line_progressed(2);
            return true;
        }
        else
        {
            _c4err("was expecting a comma");
        }
    }
    else
    {
        _c4err("internal error");
    }

    return true;
}

//-----------------------------------------------------------------------------
bool Parser::_handle_seq_blck()
{
    _c4dbgpf("handle_seq_impl: node_id={} level={}", m_state->node_id, m_state->level);
    csubstr rem = m_state->line_contents.rem;

    _RYML_CB_ASSERT(m_stack.m_callbacks, has_all(RSEQ));
    _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RKEY));
    _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(FLOW));

    if(rem.begins_with('#'))
    {
        _c4dbgp("it's a comment");
        rem = _scan_comment();
        return true;
    }
    if(has_any(RNXT))
    {
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RVAL));

        if(_handle_indentation())
            return true;

        if(rem.begins_with("- ") _RYML_WITH_TAB_TOKENS( || rem.begins_with("-\t")))
        {
            _c4dbgp("expect another val");
            addrem_flags(RVAL, RNXT);
            _line_progressed(2);
            return true;
        }
        else if(rem == '-')
        {
            _c4dbgp("expect another val");
            addrem_flags(RVAL, RNXT);
            _line_progressed(1);
            return true;
        }
        else if(rem.begins_with_any(" \t"))
        {
            _RYML_CB_ASSERT(m_stack.m_callbacks,  ! _at_line_begin());
            _skipchars(" \t");
            return true;
        }
        else if(rem.begins_with("..."))
        {
            _c4dbgp("got stream end '...'");
            _end_stream();
            _line_progressed(3);
            return true;
        }
        else if(rem.begins_with("---"))
        {
            _c4dbgp("got document start '---'");
            _start_new_doc(rem);
            return true;
        }
        else
        {
            _c4err("parse error");
        }
    }
    else if(has_any(RVAL))
    {
        // there can be empty values
        if(_handle_indentation())
            return true;

        csubstr s;
        bool is_quoted;
        if(_scan_scalar_seq_blck(&s, &is_quoted)) // this also progresses the line
        {
            _c4dbgpf("it's a{} scalar", is_quoted ? " quoted" : "");

            rem = m_state->line_contents.rem;
            if(_RYML_WITH_OR_WITHOUT_TAB_TOKENS(rem.begins_with_any(" \t"), rem.begins_with(' ')))
            {
                _c4dbgp("skipping whitespace...");
                size_t skip = rem.first_not_of(_RYML_WITH_OR_WITHOUT_TAB_TOKENS(" \t", ' '));
                if(skip == csubstr::npos)
                    skip = rem.len; // maybe the line is just whitespace
                _line_progressed(skip);
                rem = rem.sub(skip);
            }

            _c4dbgpf("rem=[{}]~~~{}~~~", rem.len, rem);
            if(!rem.begins_with('#') && (rem.ends_with(':') || rem.begins_with(": ") _RYML_WITH_TAB_TOKENS( || rem.begins_with(":\t"))))
            {
                _c4dbgp("actually, the scalar is the first key of a map, and it opens a new scope");
                if(m_key_anchor.empty())
                    _move_val_anchor_to_key_anchor();
                if(m_key_tag.empty())
                    _move_val_tag_to_key_tag();
                addrem_flags(RNXT, RVAL); // before _push_level! This prepares the current level for popping by setting it to RNXT
                _push_level();
                _start_map();
                _store_scalar(s, is_quoted);
                if( ! _maybe_set_indentation_from_anchor_or_tag())
                {
                    _c4dbgpf("set indentation from scalar: {}", m_state->scalar_col);
                    _set_indentation(m_state->scalar_col); // this is the column where the scalar starts
                }
                _move_key_tag2_to_key_tag();
                addrem_flags(RVAL, RKEY);
                _line_progressed(1);
            }
            else
            {
                _c4dbgp("appending val to current seq");
                _append_val(s, is_quoted);
                addrem_flags(RNXT, RVAL);
            }
            return true;
        }
        else if(rem.begins_with("- ") _RYML_WITH_TAB_TOKENS( || rem.begins_with("-\t")))
        {
            if(_rval_dash_start_or_continue_seq())
                _line_progressed(2);
            return true;
        }
        else if(rem == '-')
        {
            if(_rval_dash_start_or_continue_seq())
                _line_progressed(1);
            return true;
        }
        else if(rem.begins_with('['))
        {
            _c4dbgp("val is a child seq, flow");
            addrem_flags(RNXT, RVAL); // before _push_level!
            _push_level(/*explicit flow*/true);
            _start_seq();
            add_flags(FLOW);
            _line_progressed(1);
            return true;
        }
        else if(rem.begins_with('{'))
        {
            _c4dbgp("val is a child map, flow");
            addrem_flags(RNXT, RVAL); // before _push_level!
            _push_level(/*explicit flow*/true);
            _start_map();
            addrem_flags(FLOW|RKEY, RVAL);
            _line_progressed(1);
            return true;
        }
        else if(rem.begins_with("? "))
        {
            _c4dbgp("val is a child map + this key is complex");
            addrem_flags(RNXT, RVAL); // before _push_level!
            _push_level();
            _start_map();
            addrem_flags(QMRK|RKEY, RVAL);
            _save_indentation();
            _line_progressed(2);
            return true;
        }
        else if(rem.begins_with(' '))
        {
            csubstr spc = rem.left_of(rem.first_not_of(' '));
            if(_at_line_begin())
            {
                _c4dbgpf("skipping value indentation: {} spaces", spc.len);
                _line_progressed(spc.len);
                return true;
            }
            else
            {
                _c4dbgpf("skipping {} spaces", spc.len);
                _line_progressed(spc.len);
                return true;
            }
        }
        else if(_handle_types())
        {
            return true;
        }
        else if(_handle_val_anchors_and_refs())
        {
            return true;
        }
        /* pathological case:
         * - &key : val
         * - &key :
         * - : val
         */
        else if((!has_all(SSCL)) &&
                (rem.begins_with(": ") || rem.left_of(rem.find("#")).trimr("\t") == ":"))
        {
            if(!m_val_anchor.empty() || !m_val_tag.empty())
            {
                _c4dbgp("val is a child map + this key is empty, with anchors or tags");
                addrem_flags(RNXT, RVAL); // before _push_level!
                _move_val_tag_to_key_tag();
                _move_val_anchor_to_key_anchor();
                _push_level();
                _start_map();
                _store_scalar_null(rem.str);
                addrem_flags(RVAL, RKEY);
                RYML_CHECK(_maybe_set_indentation_from_anchor_or_tag()); // one of them must exist
                _line_progressed(rem.begins_with(": ") ? 2u : 1u);
                return true;
            }
            else
            {
                _c4dbgp("val is a child map + this key is empty, no anchors or tags");
                addrem_flags(RNXT, RVAL); // before _push_level!
                size_t ind = m_state->indref;
                _push_level();
                _start_map();
                _store_scalar_null(rem.str);
                addrem_flags(RVAL, RKEY);
                _c4dbgpf("set indentation from map anchor: {}", ind + 2);
                _set_indentation(ind + 2); // this is the column where the map starts
                _line_progressed(rem.begins_with(": ") ? 2u : 1u);
                return true;
            }
        }
        else
        {
            _c4err("parse error");
        }
    }

    return false;
}

//-----------------------------------------------------------------------------

bool Parser::_rval_dash_start_or_continue_seq()
{
    size_t ind = m_state->line_contents.current_col();
    _RYML_CB_ASSERT(m_stack.m_callbacks, ind >= m_state->indref);
    size_t delta_ind = ind - m_state->indref;
    if( ! delta_ind)
    {
        _c4dbgp("prev val was empty");
        addrem_flags(RNXT, RVAL);
        _append_val_null(&m_state->line_contents.full[ind]);
        return false;
    }
    _c4dbgp("val is a nested seq, indented");
    addrem_flags(RNXT, RVAL); // before _push_level!
    _push_level();
    _start_seq();
    _save_indentation();
    return true;
}

//-----------------------------------------------------------------------------
bool Parser::_handle_map_flow()
{
    // explicit flow, ie, inside {}, separated by commas
    _c4dbgpf("handle_map_flow: node_id={}  level={}", m_state->node_id, m_state->level);
    csubstr rem = m_state->line_contents.rem;

    _RYML_CB_ASSERT(m_stack.m_callbacks, has_all(RMAP|FLOW));

    if(rem.begins_with(' '))
    {
        // with explicit flow, indentation does not matter
        _c4dbgp("starts with spaces");
        _skipchars(' ');
        return true;
    }
    _RYML_WITH_TAB_TOKENS(else if(rem.begins_with('\t'))
    {
        // with explicit flow, indentation does not matter
        _c4dbgp("starts with tabs");
        _skipchars('\t');
        return true;
    })
    else if(rem.begins_with('#'))
    {
        _c4dbgp("it's a comment");
        rem = _scan_comment(); // also progresses the line
        return true;
    }
    else if(rem.begins_with('}'))
    {
        _c4dbgp("end the map");
        if(has_all(SSCL))
        {
            _c4dbgp("the last val was null");
            _append_key_val_null(rem.str - 1);
            rem_flags(RVAL);
        }
        _pop_level();
        _line_progressed(1);
        if(has_all(RSEQIMAP))
        {
            _c4dbgp("stopping implicitly nested 1x map");
            _stop_seqimap();
            _pop_level();
        }
        return true;
    }

    if(has_any(RNXT))
    {
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RKEY));
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RVAL));
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RSEQIMAP));

        if(rem.begins_with(", "))
        {
            _c4dbgp("seq: expect next keyval");
            addrem_flags(RKEY, RNXT);
            _line_progressed(2);
            return true;
        }
        else if(rem.begins_with(','))
        {
            _c4dbgp("seq: expect next keyval");
            addrem_flags(RKEY, RNXT);
            _line_progressed(1);
            return true;
        }
        else
        {
            _c4err("parse error");
        }
    }
    else if(has_any(RKEY))
    {
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RNXT));
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RVAL));

        bool is_quoted;
        if(has_none(SSCL) && _scan_scalar_map_flow(&rem, &is_quoted))
        {
            _c4dbgp("it's a scalar");
            _store_scalar(rem, is_quoted);
            rem = m_state->line_contents.rem;
            csubstr trimmed = rem.triml(" \t");
            if(trimmed.len && (trimmed.begins_with(": ") || trimmed.begins_with_any(":,}") _RYML_WITH_TAB_TOKENS( || rem.begins_with(":\t"))))
            {
                _RYML_CB_ASSERT(m_stack.m_callbacks, trimmed.str >= rem.str);
                size_t num = static_cast<size_t>(trimmed.str - rem.str);
                _c4dbgpf("trimming {} whitespace after the scalar: '{}' --> '{}'", num, rem, rem.sub(num));
                rem = rem.sub(num);
                _line_progressed(num);
            }
        }

        if(rem.begins_with(": ") _RYML_WITH_TAB_TOKENS( || rem.begins_with(":\t")))
        {
            _c4dbgp("wait for val");
            addrem_flags(RVAL, RKEY|QMRK);
            _line_progressed(2);
            if(!has_all(SSCL))
            {
                _c4dbgp("no key was found, defaulting to empty key ''");
                _store_scalar_null(rem.str);
            }
            return true;
        }
        else if(rem == ':')
        {
            _c4dbgp("wait for val");
            addrem_flags(RVAL, RKEY|QMRK);
            _line_progressed(1);
            if(!has_all(SSCL))
            {
                _c4dbgp("no key was found, defaulting to empty key ''");
                _store_scalar_null(rem.str);
            }
            return true;
        }
        else if(rem.begins_with('?'))
        {
            _c4dbgp("complex key");
            add_flags(QMRK);
            _line_progressed(1);
            return true;
        }
        else if(rem.begins_with(','))
        {
            _c4dbgp("prev scalar was a key with null value");
            _append_key_val_null(rem.str - 1);
            _line_progressed(1);
            return true;
        }
        else if(rem.begins_with('}'))
        {
            _c4dbgp("map terminates after a key...");
            _RYML_CB_ASSERT(m_stack.m_callbacks, has_all(SSCL));
            _c4dbgp("the last val was null");
            _append_key_val_null(rem.str - 1);
            rem_flags(RVAL);
            if(has_all(RSEQIMAP))
            {
                _c4dbgp("stopping implicitly nested 1x map");
                _stop_seqimap();
                _pop_level();
            }
            _pop_level();
            _line_progressed(1);
            return true;
        }
        else if(_handle_types())
        {
            return true;
        }
        else if(_handle_key_anchors_and_refs())
        {
            return true;
        }
        else if(rem == "")
        {
            return true;
        }
        else
        {
            size_t pos = rem.first_not_of(" \t");
            if(pos == csubstr::npos)
               pos = 0;
            rem = rem.sub(pos);
            if(rem.begins_with(':'))
            {
                _c4dbgp("wait for val");
                addrem_flags(RVAL, RKEY|QMRK);
                _line_progressed(pos + 1);
                if(!has_all(SSCL))
                {
                    _c4dbgp("no key was found, defaulting to empty key ''");
                    _store_scalar_null(rem.str);
                }
                return true;
            }
            else if(rem.begins_with('#'))
            {
                _c4dbgp("it's a comment");
                _line_progressed(pos);
                rem = _scan_comment(); // also progresses the line
                return true;
            }
            else
            {
                _c4err("parse error");
            }
        }
    }
    else if(has_any(RVAL))
    {
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RNXT));
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RKEY));
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_all(SSCL));
        bool is_quoted;
        if(_scan_scalar_map_flow(&rem, &is_quoted))
        {
            _c4dbgp("it's a scalar");
            addrem_flags(RNXT, RVAL|RKEY);
            _append_key_val(rem, is_quoted);
            if(has_all(RSEQIMAP))
            {
                _c4dbgp("stopping implicitly nested 1x map");
                _stop_seqimap();
                _pop_level();
            }
            return true;
        }
        else if(rem.begins_with('['))
        {
            _c4dbgp("val is a child seq");
            addrem_flags(RNXT, RVAL|RKEY); // before _push_level!
            _push_level(/*explicit flow*/true);
            _move_scalar_from_top();
            _start_seq();
            add_flags(FLOW);
            _line_progressed(1);
            return true;
        }
        else if(rem.begins_with('{'))
        {
            _c4dbgp("val is a child map");
            addrem_flags(RNXT, RVAL|RKEY); // before _push_level!
            _push_level(/*explicit flow*/true);
            _move_scalar_from_top();
            _start_map();
            addrem_flags(FLOW|RKEY, RNXT|RVAL);
            _line_progressed(1);
            return true;
        }
        else if(_handle_types())
        {
            return true;
        }
        else if(_handle_val_anchors_and_refs())
        {
            return true;
        }
        else if(rem.begins_with(','))
        {
            _c4dbgp("appending empty val");
            _append_key_val_null(rem.str - 1);
            addrem_flags(RKEY, RVAL);
            _line_progressed(1);
            if(has_any(RSEQIMAP))
            {
                _c4dbgp("stopping implicitly nested 1x map");
                _stop_seqimap();
                _pop_level();
            }
            return true;
        }
        else if(has_any(RSEQIMAP) && rem.begins_with(']'))
        {
            _c4dbgp("stopping implicitly nested 1x map");
            if(has_any(SSCL))
            {
                _append_key_val_null(rem.str - 1);
            }
            _stop_seqimap();
            _pop_level();
            return true;
        }
        else
        {
            _c4err("parse error");
        }
    }
    else
    {
        _c4err("internal error");
    }

    return false;
}

//-----------------------------------------------------------------------------
bool Parser::_handle_map_blck()
{
    _c4dbgpf("handle_map_blck: node_id={}  level={}", m_state->node_id, m_state->level);
    csubstr rem = m_state->line_contents.rem;

    _RYML_CB_ASSERT(m_stack.m_callbacks, has_all(RMAP));
    _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(FLOW));

    if(rem.begins_with('#'))
    {
        _c4dbgp("it's a comment");
        rem = _scan_comment();
        return true;
    }

    if(has_any(RNXT))
    {
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RKEY));
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RVAL));
        // actually, we don't need RNXT in indent-based maps.
        addrem_flags(RKEY, RNXT);
    }

    if(_handle_indentation())
    {
        _c4dbgp("indentation token");
        return true;
    }

    if(has_any(RKEY))
    {
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RNXT));
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RVAL));

        _c4dbgp("RMAP|RKEY read scalar?");
        bool is_quoted;
        if(_scan_scalar_map_blck(&rem, &is_quoted)) // this also progresses the line
        {
            _c4dbgpf("it's a{} scalar", is_quoted ? " quoted" : "");
            if(has_all(QMRK|SSCL))
            {
                _c4dbgpf("current key is QMRK; SSCL is set. so take store scalar='{}' as key and add an empty val", m_state->scalar);
                _append_key_val_null(rem.str - 1);
            }
            _store_scalar(rem, is_quoted);
            if(has_all(QMRK|RSET))
            {
                _c4dbgp("it's a complex key, so use null value '~'");
                _append_key_val_null(rem.str);
            }
            rem = m_state->line_contents.rem;

            if(rem.begins_with(':'))
            {
                _c4dbgp("wait for val");
                addrem_flags(RVAL, RKEY|QMRK);
                _line_progressed(1);
                rem = m_state->line_contents.rem;
                if(rem.begins_with_any(" \t"))
                {
                    _RYML_CB_ASSERT(m_stack.m_callbacks,  ! _at_line_begin());
                    rem = rem.left_of(rem.first_not_of(" \t"));
                    _c4dbgpf("skip {} spaces/tabs", rem.len);
                    _line_progressed(rem.len);
                }
            }
            return true;
        }
        else if(rem.begins_with_any(" \t"))
        {
            size_t pos = rem.first_not_of(" \t");
            if(pos == npos)
                pos = rem.len;
            _c4dbgpf("skip {} spaces/tabs", pos);
            _line_progressed(pos);
            return true;
        }
        else if(rem == '?' || rem.begins_with("? "))
        {
            _c4dbgp("it's a complex key");
            _line_progressed(rem.begins_with("? ") ? 2u : 1u);
            if(has_any(SSCL))
                _append_key_val_null(rem.str - 1);
            add_flags(QMRK);
            return true;
        }
        else if(has_all(QMRK) && rem.begins_with(':'))
        {
            _c4dbgp("complex key finished");
            if(!has_any(SSCL))
                _store_scalar_null(rem.str);
            addrem_flags(RVAL, RKEY|QMRK);
            _line_progressed(1);
            rem = m_state->line_contents.rem;
            if(rem.begins_with(' '))
            {
                _RYML_CB_ASSERT(m_stack.m_callbacks,  ! _at_line_begin());
                _skipchars(' ');
            }
            return true;
        }
        else if(rem == ':' || rem.begins_with(": ") _RYML_WITH_TAB_TOKENS( || rem.begins_with(":\t")))
        {
            _c4dbgp("key finished");
            if(!has_all(SSCL))
            {
                _c4dbgp("key was empty...");
                _store_scalar_null(rem.str);
                rem_flags(QMRK);
            }
            addrem_flags(RVAL, RKEY);
            _line_progressed(rem == ':' ? 1 : 2);
            return true;
        }
        else if(rem.begins_with("..."))
        {
            _c4dbgp("end current document");
            _end_stream();
            _line_progressed(3);
            return true;
        }
        else if(rem.begins_with("---"))
        {
            _c4dbgp("start new document '---'");
            _start_new_doc(rem);
            return true;
        }
        else if(_handle_types())
        {
            return true;
        }
        else if(_handle_key_anchors_and_refs())
        {
            return true;
        }
        else
        {
            _c4err("parse error");
        }
    }
    else if(has_any(RVAL))
    {
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RNXT));
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RKEY));

        _c4dbgp("RMAP|RVAL read scalar?");
        csubstr s;
        bool is_quoted;
        if(_scan_scalar_map_blck(&s, &is_quoted)) // this also progresses the line
        {
            _c4dbgpf("it's a{} scalar", is_quoted ? " quoted" : "");

            rem = m_state->line_contents.rem;

            if(rem.begins_with(": "))
            {
                _c4dbgp("actually, the scalar is the first key of a map");
                addrem_flags(RKEY, RVAL); // before _push_level! This prepares the current level for popping by setting it to RNXT
                _push_level();
                _move_scalar_from_top();
                _move_val_anchor_to_key_anchor();
                _start_map();
                _save_indentation(m_state->scalar_col);
                addrem_flags(RVAL, RKEY);
                _line_progressed(2);
            }
            else if(rem.begins_with(':'))
            {
                _c4dbgp("actually, the scalar is the first key of a map, and it opens a new scope");
                addrem_flags(RKEY, RVAL); // before _push_level! This prepares the current level for popping by setting it to RNXT
                _push_level();
                _move_scalar_from_top();
                _move_val_anchor_to_key_anchor();
                _start_map();
                _save_indentation(/*behind*/s.len);
                addrem_flags(RVAL, RKEY);
                _line_progressed(1);
            }
            else
            {
                _c4dbgp("appending keyval to current map");
                _append_key_val(s, is_quoted);
                addrem_flags(RKEY, RVAL);
            }
            return true;
        }
        else if(rem.begins_with("- ") _RYML_WITH_TAB_TOKENS( || rem.begins_with("-\t")))
        {
            _c4dbgp("val is a nested seq, indented");
            addrem_flags(RKEY, RVAL); // before _push_level!
            _push_level();
            _move_scalar_from_top();
            _start_seq();
            _save_indentation();
            _line_progressed(2);
            return true;
        }
        else if(rem == '-')
        {
            _c4dbgp("maybe a seq. start unknown, indented");
            _start_unk();
            _save_indentation();
            _line_progressed(1);
            return true;
        }
        else if(rem.begins_with('['))
        {
            _c4dbgp("val is a child seq, flow");
            addrem_flags(RKEY, RVAL); // before _push_level!
            _push_level(/*explicit flow*/true);
            _move_scalar_from_top();
            _start_seq();
            add_flags(FLOW);
            _line_progressed(1);
            return true;
        }
        else if(rem.begins_with('{'))
        {
            _c4dbgp("val is a child map, flow");
            addrem_flags(RKEY, RVAL); // before _push_level!
            _push_level(/*explicit flow*/true);
            _move_scalar_from_top();
            _start_map();
            addrem_flags(FLOW|RKEY, RVAL);
            _line_progressed(1);
            return true;
        }
        else if(rem.begins_with(' '))
        {
            csubstr spc = rem.left_of(rem.first_not_of(' '));
            if(_at_line_begin())
            {
                _c4dbgpf("skipping value indentation: {} spaces", spc.len);
                _line_progressed(spc.len);
                return true;
            }
            else
            {
                _c4dbgpf("skipping {} spaces", spc.len);
                _line_progressed(spc.len);
                return true;
            }
        }
        else if(_handle_types())
        {
            return true;
        }
        else if(_handle_val_anchors_and_refs())
        {
            return true;
        }
        else if(rem.begins_with("--- ") || rem == "---" || rem.begins_with("---\t"))
        {
            _start_new_doc(rem);
            return true;
        }
        else if(rem.begins_with("..."))
        {
            _c4dbgp("end current document");
            _end_stream();
            _line_progressed(3);
            return true;
        }
        else
        {
            _c4err("parse error");
        }
    }
    else
    {
        _c4err("internal error");
    }

    return false;
}


//-----------------------------------------------------------------------------
bool Parser::_handle_top()
{
    _c4dbgp("handle_top");
    csubstr rem = m_state->line_contents.rem;

    if(rem.begins_with('#'))
    {
        _c4dbgp("a comment line");
        _scan_comment();
        return true;
    }

    csubstr trimmed = rem.triml(' ');

    if(trimmed.begins_with('%'))
    {
        _handle_directive(trimmed);
        _line_progressed(rem.len);
        return true;
    }
    else if(trimmed.begins_with("--- ") || trimmed == "---" || trimmed.begins_with("---\t"))
    {
        _start_new_doc(rem);
        if(trimmed.len < rem.len)
        {
            _line_progressed(rem.len - trimmed.len);
            _save_indentation();
        }
        return true;
    }
    else if(trimmed.begins_with("..."))
    {
        _c4dbgp("end current document");
        _end_stream();
        if(trimmed.len < rem.len)
        {
            _line_progressed(rem.len - trimmed.len);
        }
        _line_progressed(3);
        return true;
    }
    else
    {
        _c4err("parse error");
    }

    return false;
}


//-----------------------------------------------------------------------------

bool Parser::_handle_key_anchors_and_refs()
{
    _RYML_CB_ASSERT(m_stack.m_callbacks, !has_any(RVAL));
    const csubstr rem = m_state->line_contents.rem;
    if(rem.begins_with('&'))
    {
        _c4dbgp("found a key anchor!!!");
        if(has_all(QMRK|SSCL))
        {
            _RYML_CB_ASSERT(m_stack.m_callbacks, has_any(RKEY));
            _c4dbgp("there is a stored key, so this anchor is for the next element");
            _append_key_val_null(rem.str - 1);
            rem_flags(QMRK);
            return true;
        }
        csubstr anchor = rem.left_of(rem.first_of(' '));
        _line_progressed(anchor.len);
        anchor = anchor.sub(1); // skip the first character
        _move_key_anchor_to_val_anchor();
        _c4dbgpf("key anchor value: '{}'", anchor);
        m_key_anchor = anchor;
        m_key_anchor_indentation = m_state->line_contents.current_col(rem);
        return true;
    }
    else if(C4_UNLIKELY(rem.begins_with('*')))
    {
        _c4err("not implemented - this should have been catched elsewhere");
        C4_NEVER_REACH();
        return false;
    }
    return false;
}

bool Parser::_handle_val_anchors_and_refs()
{
    _RYML_CB_ASSERT(m_stack.m_callbacks, !has_any(RKEY));
    const csubstr rem = m_state->line_contents.rem;
    if(rem.begins_with('&'))
    {
        csubstr anchor = rem.left_of(rem.first_of(' '));
        _line_progressed(anchor.len);
        anchor = anchor.sub(1); // skip the first character
        _c4dbgpf("val: found an anchor: '{}', indentation={}!!!", anchor, m_state->line_contents.current_col(rem));
        if(m_val_anchor.empty())
        {
            _c4dbgpf("save val anchor: '{}'", anchor);
            m_val_anchor = anchor;
            m_val_anchor_indentation = m_state->line_contents.current_col(rem);
        }
        else
        {
            _c4dbgpf("there is a pending val anchor '{}'", m_val_anchor);
            if(m_tree->is_seq(m_state->node_id))
            {
                if(m_tree->has_children(m_state->node_id))
                {
                    _c4dbgpf("current node={} is a seq, has {} children", m_state->node_id, m_tree->num_children(m_state->node_id));
                    _c4dbgpf("... so take the new one as a key anchor '{}'", anchor);
                    m_key_anchor = anchor;
                    m_key_anchor_indentation = m_state->line_contents.current_col(rem);
                }
                else
                {
                    _c4dbgpf("current node={} is a seq, has no children", m_state->node_id);
                    if(m_tree->has_val_anchor(m_state->node_id))
                    {
                        _c4dbgpf("... node={} already has val anchor: '{}'", m_state->node_id, m_tree->val_anchor(m_state->node_id));
                        _c4dbgpf("... so take the new one as a key anchor '{}'", anchor);
                        m_key_anchor = anchor;
                        m_key_anchor_indentation = m_state->line_contents.current_col(rem);
                    }
                    else
                    {
                        _c4dbgpf("... so set pending val anchor: '{}' on current node {}", m_val_anchor, m_state->node_id);
                        m_tree->set_val_anchor(m_state->node_id, m_val_anchor);
                        m_val_anchor = anchor;
                        m_val_anchor_indentation = m_state->line_contents.current_col(rem);
                    }
                }
            }
        }
        return true;
    }
    else if(C4_UNLIKELY(rem.begins_with('*')))
    {
        _c4err("not implemented - this should have been catched elsewhere");
        C4_NEVER_REACH();
        return false;
    }
    return false;
}

void Parser::_move_key_anchor_to_val_anchor()
{
    if(m_key_anchor.empty())
        return;
    _c4dbgpf("move current key anchor to val slot: key='{}' -> val='{}'", m_key_anchor, m_val_anchor);
    if(!m_val_anchor.empty())
        _c4err("triple-pending anchor");
    m_val_anchor = m_key_anchor;
    m_val_anchor_indentation = m_key_anchor_indentation;
    m_key_anchor = {};
    m_key_anchor_indentation = {};
}

void Parser::_move_val_anchor_to_key_anchor()
{
    if(m_val_anchor.empty())
        return;
    if(!_token_is_from_this_line(m_val_anchor))
        return;
    _c4dbgpf("move current val anchor to key slot: key='{}' <- val='{}'", m_key_anchor, m_val_anchor);
    if(!m_key_anchor.empty())
        _c4err("triple-pending anchor");
    m_key_anchor = m_val_anchor;
    m_key_anchor_indentation = m_val_anchor_indentation;
    m_val_anchor = {};
    m_val_anchor_indentation = {};
}

void Parser::_move_key_tag_to_val_tag()
{
    if(m_key_tag.empty())
        return;
    _c4dbgpf("move key tag to val tag: key='{}' -> val='{}'", m_key_tag, m_val_tag);
    m_val_tag = m_key_tag;
    m_val_tag_indentation = m_key_tag_indentation;
    m_key_tag.clear();
    m_key_tag_indentation = 0;
}

void Parser::_move_val_tag_to_key_tag()
{
    if(m_val_tag.empty())
        return;
    if(!_token_is_from_this_line(m_val_tag))
        return;
    _c4dbgpf("move val tag to key tag: key='{}' <- val='{}'", m_key_tag, m_val_tag);
    m_key_tag = m_val_tag;
    m_key_tag_indentation = m_val_tag_indentation;
    m_val_tag.clear();
    m_val_tag_indentation = 0;
}

void Parser::_move_key_tag2_to_key_tag()
{
    if(m_key_tag2.empty())
        return;
    _c4dbgpf("move key tag2 to key tag: key='{}' <- key2='{}'", m_key_tag, m_key_tag2);
    m_key_tag = m_key_tag2;
    m_key_tag_indentation = m_key_tag2_indentation;
    m_key_tag2.clear();
    m_key_tag2_indentation = 0;
}


//-----------------------------------------------------------------------------

bool Parser::_handle_types()
{
    csubstr rem = m_state->line_contents.rem.triml(' ');
    csubstr t;

    if(rem.begins_with("!!"))
    {
        _c4dbgp("begins with '!!'");
        t = rem.left_of(rem.first_of(" ,"));
        _RYML_CB_ASSERT(m_stack.m_callbacks, t.len >= 2);
        //t = t.sub(2);
        if(t == "!!set")
            add_flags(RSET);
    }
    else if(rem.begins_with("!<"))
    {
        _c4dbgp("begins with '!<'");
        t = rem.left_of(rem.first_of('>'), true);
        _RYML_CB_ASSERT(m_stack.m_callbacks, t.len >= 2);
        //t = t.sub(2, t.len-1);
    }
    else if(rem.begins_with("!h!"))
    {
        _c4dbgp("begins with '!h!'");
        t = rem.left_of(rem.first_of(' '));
        _RYML_CB_ASSERT(m_stack.m_callbacks, t.len >= 3);
        //t = t.sub(3);
    }
    else if(rem.begins_with('!'))
    {
        _c4dbgp("begins with '!'");
        t = rem.left_of(rem.first_of(' '));
        _RYML_CB_ASSERT(m_stack.m_callbacks, t.len >= 1);
        //t = t.sub(1);
    }

    if(t.empty())
        return false;

    if(has_all(QMRK|SSCL))
    {
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_any(RKEY));
        _c4dbgp("there is a stored key, so this tag is for the next element");
        _append_key_val_null(rem.str - 1);
        rem_flags(QMRK);
    }

    #ifdef RYML_NO_COVERAGE__TO_BE_DELETED
    const char *tag_beginning = rem.str;
    #endif
    size_t tag_indentation = m_state->line_contents.current_col(t);
    _c4dbgpf("there was a tag: '{}', indentation={}", t, tag_indentation);
    _RYML_CB_ASSERT(m_stack.m_callbacks, t.end() > m_state->line_contents.rem.begin());
    _line_progressed(static_cast<size_t>(t.end() - m_state->line_contents.rem.begin()));
    {
        size_t pos = m_state->line_contents.rem.first_not_of(" \t");
        if(pos != csubstr::npos)
            _line_progressed(pos);
    }

    if(has_all(RMAP|RKEY))
    {
        _c4dbgpf("saving map key tag '{}'", t);
        _RYML_CB_ASSERT(m_stack.m_callbacks, m_key_tag.empty());
        m_key_tag = t;
        m_key_tag_indentation = tag_indentation;
    }
    else if(has_all(RMAP|RVAL))
    {
        /* foo: !!str
         * !!str : bar  */
        rem = m_state->line_contents.rem;
        rem = rem.left_of(rem.find("#"));
        rem = rem.trimr(" \t");
        _c4dbgpf("rem='{}'", rem);
        #ifdef RYML_NO_COVERAGE__TO_BE_DELETED
        if(rem == ':' || rem.begins_with(": "))
        {
            _c4dbgp("the last val was null, and this is a tag from a null key");
            _append_key_val_null(tag_beginning - 1);
            _store_scalar_null(rem.str - 1);
            // do not change the flag to key, it is ~
            _RYML_CB_ASSERT(m_stack.m_callbacks, rem.begin() > m_state->line_contents.rem.begin());
            size_t token_len = rem == ':' ? 1 : 2;
            _line_progressed(static_cast<size_t>(token_len + rem.begin() - m_state->line_contents.rem.begin()));
        }
        #endif
        _c4dbgpf("saving map val tag '{}'", t);
        _RYML_CB_ASSERT(m_stack.m_callbacks, m_val_tag.empty());
        m_val_tag = t;
        m_val_tag_indentation = tag_indentation;
    }
    else if(has_all(RSEQ|RVAL) || has_all(RTOP|RUNK|NDOC))
    {
        if(m_val_tag.empty())
        {
            _c4dbgpf("saving seq/doc val tag '{}'", t);
            m_val_tag = t;
            m_val_tag_indentation = tag_indentation;
        }
        else
        {
            _c4dbgpf("saving seq/doc key tag '{}'", t);
            m_key_tag = t;
            m_key_tag_indentation = tag_indentation;
        }
    }
    else if(has_all(RTOP|RUNK) || has_any(RUNK))
    {
        rem = m_state->line_contents.rem;
        rem = rem.left_of(rem.find("#"));
        rem = rem.trimr(" \t");
        if(rem.empty())
        {
            _c4dbgpf("saving val tag '{}'", t);
            _RYML_CB_ASSERT(m_stack.m_callbacks, m_val_tag.empty());
            m_val_tag = t;
            m_val_tag_indentation = tag_indentation;
        }
        else
        {
            _c4dbgpf("saving key tag '{}'", t);
            if(m_key_tag.empty())
            {
                m_key_tag = t;
                m_key_tag_indentation = tag_indentation;
            }
            else
            {
                /* handle this case:
                 * !!str foo: !!map
                 *   !!int 1: !!float 20.0
                 *   !!int 3: !!float 40.0
                 *
                 * (m_key_tag would be !!str and m_key_tag2 would be !!int)
                 */
                m_key_tag2 = t;
                m_key_tag2_indentation = tag_indentation;
            }
        }
    }
    else
    {
        _c4err("internal error");
    }

    if(m_val_tag.not_empty())
    {
        YamlTag_e tag = to_tag(t);
        if(tag == TAG_STR)
        {
            _c4dbgpf("tag '{}' is a str-type tag", t);
            if(has_all(RTOP|RUNK|NDOC))
            {
                _c4dbgpf("docval. slurping the string. pos={}", m_state->pos.offset);
                csubstr scalar = _slurp_doc_scalar();
                _c4dbgpf("docval. after slurp: {}, at node {}: '{}'", m_state->pos.offset, m_state->node_id, scalar);
                m_tree->to_val(m_state->node_id, scalar, DOC);
                _c4dbgpf("docval. val tag {} -> {}", m_val_tag, normalize_tag(m_val_tag));
                m_tree->set_val_tag(m_state->node_id, normalize_tag(m_val_tag));
                m_val_tag.clear();
                if(!m_val_anchor.empty())
                {
                    _c4dbgpf("setting val anchor[{}]='{}'", m_state->node_id, m_val_anchor);
                    m_tree->set_val_anchor(m_state->node_id, m_val_anchor);
                    m_val_anchor.clear();
                }
                _end_stream();
            }
        }
    }
    return true;
}

//-----------------------------------------------------------------------------
csubstr Parser::_slurp_doc_scalar()
{
    csubstr s = m_state->line_contents.rem;
    size_t pos = m_state->pos.offset;
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_state->line_contents.full.find("---") != csubstr::npos);
    _c4dbgpf("slurp 0 '{}'. REM='{}'", s, m_buf.sub(m_state->pos.offset));
    if(s.len == 0)
    {
        _line_ended();
        _scan_line();
        s = m_state->line_contents.rem;
        pos = m_state->pos.offset;
    }

    size_t skipws = s.first_not_of(" \t");
    _c4dbgpf("slurp 1 '{}'. REM='{}'", s, m_buf.sub(m_state->pos.offset));
    if(skipws != npos)
    {
        _line_progressed(skipws);
        s = m_state->line_contents.rem;
        pos = m_state->pos.offset;
        _c4dbgpf("slurp 2 '{}'. REM='{}'", s, m_buf.sub(m_state->pos.offset));
    }

    _RYML_CB_ASSERT(m_stack.m_callbacks, m_val_anchor.empty());
    _handle_val_anchors_and_refs();
    if(!m_val_anchor.empty())
    {
        s = m_state->line_contents.rem;
        skipws = s.first_not_of(" \t");
        if(skipws != npos)
        {
            _line_progressed(skipws);
        }
        s = m_state->line_contents.rem;
        pos = m_state->pos.offset;
        _c4dbgpf("slurp 3 '{}'. REM='{}'", s, m_buf.sub(m_state->pos.offset));
    }

    if(s.begins_with('\''))
    {
        m_state->scalar_col = m_state->line_contents.current_col(s);
        return _scan_squot_scalar();
    }
    else if(s.begins_with('"'))
    {
        m_state->scalar_col = m_state->line_contents.current_col(s);
        return _scan_dquot_scalar();
    }
    else if(s.begins_with('|') || s.begins_with('>'))
    {
        return _scan_block();
    }

    _c4dbgpf("slurp 4 '{}'. REM='{}'", s, m_buf.sub(m_state->pos.offset));

    m_state->scalar_col = m_state->line_contents.current_col(s);
    _RYML_CB_ASSERT(m_stack.m_callbacks, s.end() >= m_buf.begin() + pos);
    _line_progressed(static_cast<size_t>(s.end() - (m_buf.begin() + pos)));

    _c4dbgpf("slurp 5 '{}'. REM='{}'", s, m_buf.sub(m_state->pos.offset));

    if(_at_line_end())
    {
        _c4dbgpf("at line end. curr='{}'", s);
        s = _extend_scanned_scalar(s);
    }

    _c4dbgpf("scalar was '{}'", s);

    return s;
}


//-----------------------------------------------------------------------------

bool Parser::_scan_scalar_seq_blck(csubstr *C4_RESTRICT scalar, bool *C4_RESTRICT quoted)
{
    _RYML_CB_ASSERT(m_stack.m_callbacks,  has_any(RSEQ));
    _RYML_CB_ASSERT(m_stack.m_callbacks,  has_any(RVAL));
    _RYML_CB_ASSERT(m_stack.m_callbacks,  ! has_any(RKEY));
    _RYML_CB_ASSERT(m_stack.m_callbacks,  ! has_any(FLOW));

    csubstr s = m_state->line_contents.rem;
    if(s.len == 0)
        return false;
    s = s.trim(" \t");
    if(s.len == 0)
        return false;

    if(s.begins_with('\''))
    {
        _c4dbgp("got a ': scanning single-quoted scalar");
        m_state->scalar_col = m_state->line_contents.current_col(s);
        *scalar = _scan_squot_scalar();
        *quoted = true;
        return true;
    }
    else if(s.begins_with('"'))
    {
        _c4dbgp("got a \": scanning double-quoted scalar");
        m_state->scalar_col = m_state->line_contents.current_col(s);
        *scalar = _scan_dquot_scalar();
        *quoted = true;
        return true;
    }
    else if(s.begins_with('|') || s.begins_with('>'))
    {
        *scalar = _scan_block();
        *quoted = true;
        return true;
    }
    else if(has_any(RTOP) && _is_doc_sep(s))
    {
        return false;
    }

    _c4dbgp("RSEQ|RVAL");
    if( ! _is_scalar_next__rseq_rval(s))
        return false;
    _RYML_WITH_TAB_TOKENS(else if(s.begins_with("-\t"))
        return false;
    )

    if(s.ends_with(':'))
    {
        --s.len;
    }
    else
    {
        auto first = s.first_of_any(": " _RYML_WITH_TAB_TOKENS( , ":\t"), " #");
        if(first)
            s.len = first.pos;
    }
    s = s.trimr(_RYML_WITH_OR_WITHOUT_TAB_TOKENS(" \t", ' '));

    if(s.empty())
        return false;

    m_state->scalar_col = m_state->line_contents.current_col(s);
    _RYML_CB_ASSERT(m_stack.m_callbacks, s.str >= m_state->line_contents.rem.str);
    _line_progressed(static_cast<size_t>(s.str - m_state->line_contents.rem.str) + s.len);

    if(_at_line_end() && s != '~')
    {
        _c4dbgpf("at line end. curr='{}'", s);
        s = _extend_scanned_scalar(s);
    }

    _c4dbgpf("scalar was '{}'", s);

    *scalar = s;
    *quoted = false;
    return true;
}

bool Parser::_scan_scalar_map_blck(csubstr *C4_RESTRICT scalar, bool *C4_RESTRICT quoted)
{
    _c4dbgp("_scan_scalar_map_blck");
    _RYML_CB_ASSERT(m_stack.m_callbacks,  has_any(RMAP));
    _RYML_CB_ASSERT(m_stack.m_callbacks,  ! has_any(FLOW));
    _RYML_CB_ASSERT(m_stack.m_callbacks,  has_any(RKEY|RVAL));

    csubstr s = m_state->line_contents.rem;
    #ifdef RYML_NO_COVERAGE__TO_BE_DELETED__OR_REFACTORED
    if(s.len == 0)
        return false;
    #endif
    s = s.trim(" \t");
    if(s.len == 0)
        return false;

    if(s.begins_with('\''))
    {
        _c4dbgp("got a ': scanning single-quoted scalar");
        m_state->scalar_col = m_state->line_contents.current_col(s);
        *scalar = _scan_squot_scalar();
        *quoted = true;
        return true;
    }
    else if(s.begins_with('"'))
    {
        _c4dbgp("got a \": scanning double-quoted scalar");
        m_state->scalar_col = m_state->line_contents.current_col(s);
        *scalar = _scan_dquot_scalar();
        *quoted = true;
        return true;
    }
    else if(s.begins_with('|') || s.begins_with('>'))
    {
        *scalar = _scan_block();
        *quoted = true;
        return true;
    }
    else if(has_any(RTOP) && _is_doc_sep(s))
    {
        return false;
    }

    if( ! _is_scalar_next__rmap(s))
        return false;

    size_t colon_token = s.find(": ");
    if(colon_token == npos)
    {
        _RYML_WITH_OR_WITHOUT_TAB_TOKENS(
            // with tab tokens
            colon_token = s.find(":\t");
            if(colon_token == npos)
            {
                _RYML_CB_ASSERT(m_stack.m_callbacks, s.len > 0);
                colon_token = s.find(':');
                if(colon_token != s.len-1)
                    colon_token = npos;
            }
            ,
            // without tab tokens
            colon_token = s.find(':');
            _RYML_CB_ASSERT(m_stack.m_callbacks, s.len > 0);
            if(colon_token != s.len-1)
                colon_token = npos;
        )
    }

    if(has_all(RKEY))
    {
        _RYML_CB_ASSERT(m_stack.m_callbacks, !s.begins_with(' '));
        if(has_any(QMRK))
        {
            _c4dbgp("RMAP|RKEY|CPLX");
            _RYML_CB_ASSERT(m_stack.m_callbacks, has_any(RMAP));
            if(s.begins_with("? ") || s == '?')
                return false;
            s = s.left_of(colon_token);
            s = s.left_of(s.first_of("#"));
            s = s.trimr(" \t");
            if(s.begins_with("---"))
                return false;
            else if(s.begins_with("..."))
                return false;
        }
        else
        {
            _c4dbgp("RMAP|RKEY");
            _RYML_CB_CHECK(m_stack.m_callbacks, !s.begins_with('{'));
            if(s.begins_with("? ") || s == '?')
                return false;
            s = s.left_of(colon_token);
            s = s.trimr(_RYML_WITH_OR_WITHOUT_TAB_TOKENS(" \t", ' '));
            if(s.begins_with("---"))
            {
                return false;
            }
            else if(s.begins_with("..."))
            {
                return false;
            }
        }
    }
    else if(has_all(RVAL))
    {
        _c4dbgp("RMAP|RVAL");
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(QMRK));
        if( ! _is_scalar_next__rmap_val(s))
            return false;
        _RYML_WITH_TAB_TOKENS(
        else if(s.begins_with("-\t"))
            return false;
        )
        _c4dbgp("RMAP|RVAL: scalar");
        s = s.left_of(s.find(" #")); // is there a comment?
        s = s.left_of(s.find("\t#")); // is there a comment?
        s = s.trim(_RYML_WITH_OR_WITHOUT_TAB_TOKENS(" \t", ' '));
        if(s.begins_with("---"))
            return false;
        #ifdef RYML_NO_COVERAGE__TO_BE_DELETED__OR_REFACTORED
        else if(s.begins_with("..."))
            return false;
        #endif
    }

    if(s.empty())
        return false;

    m_state->scalar_col = m_state->line_contents.current_col(s);
    _RYML_CB_ASSERT(m_stack.m_callbacks, s.str >= m_state->line_contents.rem.str);
    _line_progressed(static_cast<size_t>(s.str - m_state->line_contents.rem.str) + s.len);

    if(_at_line_end() && s != '~')
    {
        _c4dbgpf("at line end. curr='{}'", s);
        s = _extend_scanned_scalar(s);
    }

    _c4dbgpf("scalar was '{}'", s);

    *scalar = s;
    *quoted = false;
    return true;
}

bool Parser::_scan_scalar_seq_flow(csubstr *C4_RESTRICT scalar, bool *C4_RESTRICT quoted)
{
    _RYML_CB_ASSERT(m_stack.m_callbacks,  has_any(RSEQ));
    _RYML_CB_ASSERT(m_stack.m_callbacks,  has_any(FLOW));
    _RYML_CB_ASSERT(m_stack.m_callbacks,  has_any(RVAL));
    _RYML_CB_ASSERT(m_stack.m_callbacks,  ! has_any(RKEY));

    csubstr s = m_state->line_contents.rem;
    if(s.len == 0)
        return false;
    s = s.trim(" \t");
    if(s.len == 0)
        return false;

    if(s.begins_with('\''))
    {
        _c4dbgp("got a ': scanning single-quoted scalar");
        m_state->scalar_col = m_state->line_contents.current_col(s);
        *scalar = _scan_squot_scalar();
        *quoted = true;
        return true;
    }
    else if(s.begins_with('"'))
    {
        _c4dbgp("got a \": scanning double-quoted scalar");
        m_state->scalar_col = m_state->line_contents.current_col(s);
        *scalar = _scan_dquot_scalar();
        *quoted = true;
        return true;
    }

    if(has_all(RVAL))
    {
        _c4dbgp("RSEQ|RVAL");
        if( ! _is_scalar_next__rseq_rval(s))
            return false;
        _RYML_WITH_TAB_TOKENS(else if(s.begins_with("-\t"))
            return false;
        )
        _c4dbgp("RSEQ|RVAL|FLOW");
        s = s.left_of(s.first_of(",]"));
        if(s.ends_with(':'))
        {
            --s.len;
        }
        else
        {
            auto first = s.first_of_any(": " _RYML_WITH_TAB_TOKENS( , ":\t"), " #");
            if(first)
                s.len = first.pos;
        }
        s = s.trimr(_RYML_WITH_OR_WITHOUT_TAB_TOKENS(" \t", ' '));
    }

    if(s.empty())
        return false;

    m_state->scalar_col = m_state->line_contents.current_col(s);
    _RYML_CB_ASSERT(m_stack.m_callbacks, s.str >= m_state->line_contents.rem.str);
    _line_progressed(static_cast<size_t>(s.str - m_state->line_contents.rem.str) + s.len);

    if(_at_line_end() && s != '~')
    {
        _c4dbgpf("at line end. curr='{}'", s);
        s = _extend_scanned_scalar(s);
    }

    _c4dbgpf("scalar was '{}'", s);

    *scalar = s;
    *quoted = false;
    return true;
}

bool Parser::_scan_scalar_map_flow(csubstr *C4_RESTRICT scalar, bool *C4_RESTRICT quoted)
{
    _RYML_CB_ASSERT(m_stack.m_callbacks,  has_any(RMAP));
    _RYML_CB_ASSERT(m_stack.m_callbacks,  has_any(FLOW));
    _RYML_CB_ASSERT(m_stack.m_callbacks,  has_any(RKEY|RVAL));

    csubstr s = m_state->line_contents.rem;
    if(s.len == 0)
        return false;
    s = s.trim(" \t");
    if(s.len == 0)
        return false;

    if(s.begins_with('\''))
    {
        _c4dbgp("got a ': scanning single-quoted scalar");
        m_state->scalar_col = m_state->line_contents.current_col(s);
        *scalar = _scan_squot_scalar();
        *quoted = true;
        return true;
    }
    else if(s.begins_with('"'))
    {
        _c4dbgp("got a \": scanning double-quoted scalar");
        m_state->scalar_col = m_state->line_contents.current_col(s);
        *scalar = _scan_dquot_scalar();
        *quoted = true;
        return true;
    }

    if( ! _is_scalar_next__rmap(s))
        return false;

    if(has_all(RKEY))
    {
        _RYML_CB_ASSERT(m_stack.m_callbacks, !s.begins_with(' '));
        size_t colon_token = s.find(": ");
        if(colon_token == npos)
        {
            _RYML_WITH_OR_WITHOUT_TAB_TOKENS(
                // with tab tokens
                colon_token = s.find(":\t");
                if(colon_token == npos)
                {
                    _RYML_CB_ASSERT(m_stack.m_callbacks, s.len > 0);
                    colon_token = s.find(':');
                    if(colon_token != s.len-1)
                        colon_token = npos;
                }
                ,
                // without tab tokens
                colon_token = s.find(':');
                _RYML_CB_ASSERT(m_stack.m_callbacks, s.len > 0);
                if(colon_token != s.len-1)
                    colon_token = npos;
            )
        }
        if(s.begins_with("? ") || s == '?')
            return false;
        if(has_any(QMRK))
        {
            _c4dbgp("RMAP|RKEY|CPLX");
            _RYML_CB_ASSERT(m_stack.m_callbacks, has_any(RMAP));
            s = s.left_of(colon_token);
            s = s.left_of(s.first_of("#"));
            s = s.left_of(s.first_of(':'));
            s = s.trimr(" \t");
            if(s.begins_with("---"))
                return false;
            else if(s.begins_with("..."))
                return false;
        }
        else
        {
            _RYML_CB_CHECK(m_stack.m_callbacks, !s.begins_with('{'));
            _c4dbgp("RMAP|RKEY");
            s = s.left_of(colon_token);
            s = s.trimr(_RYML_WITH_OR_WITHOUT_TAB_TOKENS(" \t", ' '));
            _c4dbgpf("RMAP|RKEY|FLOW: '{}'", s);
            s = s.left_of(s.first_of(",}"));
            if(s.ends_with(':'))
                --s.len;
        }
    }
    else if(has_all(RVAL))
    {
        _c4dbgp("RMAP|RVAL");
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(QMRK));
        if( ! _is_scalar_next__rmap_val(s))
            return false;
        _RYML_WITH_TAB_TOKENS(else if(s.begins_with("-\t"))
            return false;
        )
        _c4dbgp("RMAP|RVAL|FLOW");
        if(has_none(RSEQIMAP))
            s = s.left_of(s.first_of(",}"));
        else
            s = s.left_of(s.first_of(",]"));
        s = s.left_of(s.find(" #")); // is there a comment?
        s = s.left_of(s.find("\t#")); // is there a comment?
        s = s.trim(_RYML_WITH_OR_WITHOUT_TAB_TOKENS(" \t", ' '));
    }

    if(s.empty())
        return false;

    m_state->scalar_col = m_state->line_contents.current_col(s);
    _RYML_CB_ASSERT(m_stack.m_callbacks, s.str >= m_state->line_contents.rem.str);
    _line_progressed(static_cast<size_t>(s.str - m_state->line_contents.rem.str) + s.len);

    if(_at_line_end() && s != '~')
    {
        _c4dbgpf("at line end. curr='{}'", s);
        s = _extend_scanned_scalar(s);
    }

    _c4dbgpf("scalar was '{}'", s);

    *scalar = s;
    *quoted = false;
    return true;
}

bool Parser::_scan_scalar_unk(csubstr *C4_RESTRICT scalar, bool *C4_RESTRICT quoted)
{
    _RYML_CB_ASSERT(m_stack.m_callbacks,  has_any(RUNK));

    csubstr s = m_state->line_contents.rem;
    if(s.len == 0)
        return false;
    s = s.trim(" \t");
    if(s.len == 0)
        return false;

    if(s.begins_with('\''))
    {
        _c4dbgp("got a ': scanning single-quoted scalar");
        m_state->scalar_col = m_state->line_contents.current_col(s);
        *scalar = _scan_squot_scalar();
        *quoted = true;
        return true;
    }
    else if(s.begins_with('"'))
    {
        _c4dbgp("got a \": scanning double-quoted scalar");
        m_state->scalar_col = m_state->line_contents.current_col(s);
        *scalar = _scan_dquot_scalar();
        *quoted = true;
        return true;
    }
    else if(s.begins_with('|') || s.begins_with('>'))
    {
        *scalar = _scan_block();
        *quoted = true;
        return true;
    }
    else if(has_any(RTOP) && _is_doc_sep(s))
    {
        return false;
    }

    _c4dbgpf("RUNK '[{}]~~~{}~~~", s.len, s);
    if( ! _is_scalar_next__runk(s))
    {
        _c4dbgp("RUNK: no scalar next");
        return false;
    }
    size_t pos = s.find(" #");
    if(pos != npos)
        s = s.left_of(pos);
    pos = s.find(": ");
    if(pos != npos)
        s = s.left_of(pos);
    else if(s.ends_with(':'))
        s = s.left_of(s.len-1);
    _RYML_WITH_TAB_TOKENS(
    else if((pos = s.find(":\t")) != npos) // TABS
        s = s.left_of(pos);
    )
    else
        s = s.left_of(s.first_of(','));
    s = s.trim(" \t");
    _c4dbgpf("RUNK: scalar='{}'", s);

    if(s.empty())
        return false;

    m_state->scalar_col = m_state->line_contents.current_col(s);
    _RYML_CB_ASSERT(m_stack.m_callbacks, s.str >= m_state->line_contents.rem.str);
    _line_progressed(static_cast<size_t>(s.str - m_state->line_contents.rem.str) + s.len);

    if(_at_line_end() && s != '~')
    {
        _c4dbgpf("at line end. curr='{}'", s);
        s = _extend_scanned_scalar(s);
    }

    _c4dbgpf("scalar was '{}'", s);

    *scalar = s;
    *quoted = false;
    return true;
}


//-----------------------------------------------------------------------------

csubstr Parser::_extend_scanned_scalar(csubstr s)
{
    if(has_all(RMAP|RKEY|QMRK))
    {
        size_t scalar_indentation = has_any(FLOW) ? 0 : m_state->scalar_col;
        _c4dbgpf("extend_scalar: explicit key! indref={} scalar_indentation={} scalar_col={}", m_state->indref, scalar_indentation, m_state->scalar_col);
        csubstr n = _scan_to_next_nonempty_line(scalar_indentation);
        if(!n.empty())
        {
            substr full = _scan_complex_key(s, n).trimr(" \t\r\n");
            if(full != s)
                s = _filter_plain_scalar(full, scalar_indentation);
        }
    }
    // deal with plain (unquoted) scalars that continue to the next line
    else if(!s.begins_with_any("*")) // cannot be a plain scalar if it starts with * (that's an anchor reference)
    {
        _c4dbgpf("extend_scalar: line ended, scalar='{}'", s);
        if(has_none(FLOW))
        {
            size_t scalar_indentation = m_state->indref + 1;
            if(has_all(RUNK) && scalar_indentation == 1)
                scalar_indentation = 0;
            csubstr n = _scan_to_next_nonempty_line(scalar_indentation);
            if(!n.empty())
            {
                _c4dbgpf("rscalar[IMPL]: state_indref={} state_indentation={} scalar_indentation={}", m_state->indref, m_state->line_contents.indentation, scalar_indentation);
                _RYML_CB_ASSERT(m_stack.m_callbacks, m_state->line_contents.full.is_super(n));
                substr full = _scan_plain_scalar_blck(s, n, scalar_indentation);
                if(full.len >= s.len)
                    s = _filter_plain_scalar(full, scalar_indentation);
            }
        }
        else
        {
            _RYML_CB_ASSERT(m_stack.m_callbacks, has_all(FLOW));
            csubstr n = _scan_to_next_nonempty_line(/*indentation*/0);
            if(!n.empty())
            {
                _c4dbgp("rscalar[FLOW]");
                substr full = _scan_plain_scalar_flow(s, n);
                s = _filter_plain_scalar(full, /*indentation*/0);
            }
        }
    }

    return s;
}


//-----------------------------------------------------------------------------

substr Parser::_scan_plain_scalar_flow(csubstr currscalar, csubstr peeked_line)
{
    static constexpr const csubstr chars = "[]{}?#,";
    size_t pos = peeked_line.first_of(chars);
    bool first = true;
    while(pos != 0)
    {
        if(has_all(RMAP|RKEY) || has_any(RUNK))
        {
            csubstr tpkl = peeked_line.triml(' ').trimr("\r\n");
            if(tpkl.begins_with(": ") || tpkl == ':')
            {
                _c4dbgpf("rscalar[FLOW]: map value starts on the peeked line: '{}'", peeked_line);
                peeked_line = peeked_line.first(0);
                break;
            }
            else
            {
                auto colon_pos = peeked_line.first_of_any(": ", ":");
                if(colon_pos && colon_pos.pos < pos)
                {
                    peeked_line = peeked_line.first(colon_pos.pos);
                    _c4dbgpf("rscalar[FLOW]: found colon at {}. peeked='{}'", colon_pos.pos, peeked_line);
                    _RYML_CB_ASSERT(m_stack.m_callbacks, peeked_line.end() >= m_state->line_contents.rem.begin());
                    _line_progressed(static_cast<size_t>(peeked_line.end() - m_state->line_contents.rem.begin()));
                    break;
                }
            }
        }
        if(pos != npos)
        {
            _c4dbgpf("rscalar[FLOW]: found special character '{}' at {}, stopping: '{}'", peeked_line[pos], pos, peeked_line.left_of(pos).trimr("\r\n"));
            peeked_line = peeked_line.left_of(pos);
            _RYML_CB_ASSERT(m_stack.m_callbacks, peeked_line.end() >= m_state->line_contents.rem.begin());
            _line_progressed(static_cast<size_t>(peeked_line.end() - m_state->line_contents.rem.begin()));
            break;
        }
        _c4dbgpf("rscalar[FLOW]: append another line, full: '{}'", peeked_line.trimr("\r\n"));
        if(!first)
        {
            RYML_CHECK(_advance_to_peeked());
        }
        peeked_line = _scan_to_next_nonempty_line(/*indentation*/0);
        if(peeked_line.empty())
        {
            _c4err("expected token or continuation");
        }
        pos = peeked_line.first_of(chars);
        first = false;
    }
    substr full(m_buf.str + (currscalar.str - m_buf.str), m_buf.begin() + m_state->pos.offset);
    full = full.trimr("\n\r ");
    return full;
}


//-----------------------------------------------------------------------------

substr Parser::_scan_plain_scalar_blck(csubstr currscalar, csubstr peeked_line, size_t indentation)
{
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_buf.is_super(currscalar));
    // NOTE. there's a problem with _scan_to_next_nonempty_line(), as it counts newlines twice
    // size_t offs = m_state->pos.offset;   // so we workaround by directly counting from the end of the given scalar
    _RYML_CB_ASSERT(m_stack.m_callbacks, currscalar.end() >= m_buf.begin());
    size_t offs = static_cast<size_t>(currscalar.end() - m_buf.begin());
    _RYML_CB_ASSERT(m_stack.m_callbacks, peeked_line.begins_with(' ', indentation));
    while(true)
    {
        _c4dbgpf("rscalar[IMPL]: continuing... ref_indentation={}", indentation);
        if(peeked_line.begins_with("...") || peeked_line.begins_with("---"))
        {
            _c4dbgpf("rscalar[IMPL]: document termination next -- bail now '{}'", peeked_line.trimr("\r\n"));
            break;
        }
        else if(( ! peeked_line.begins_with(' ', indentation))) // is the line deindented?
        {
            if(!peeked_line.trim(" \r\n\t").empty()) // is the line not blank?
            {
                _c4dbgpf("rscalar[IMPL]: deindented line, not blank -- bail now '{}'", peeked_line.trimr("\r\n"));
                break;
            }
            _c4dbgpf("rscalar[IMPL]: line is blank and has less indentation: ref={} line={}: '{}'", indentation, peeked_line.first_not_of(' ') == csubstr::npos ? 0 : peeked_line.first_not_of(' '), peeked_line.trimr("\r\n"));
            _c4dbgpf("rscalar[IMPL]: ... searching for a line starting at indentation {}", indentation);
            csubstr next_peeked = _scan_to_next_nonempty_line(indentation);
            if(next_peeked.empty())
            {
                _c4dbgp("rscalar[IMPL]: ... finished.");
                break;
            }
            _c4dbgp("rscalar[IMPL]: ... continuing.");
            peeked_line = next_peeked;
        }

        _c4dbgpf("rscalar[IMPL]: line contents: '{}'", peeked_line.right_of(indentation, true).trimr("\r\n"));
        size_t token_pos;
        if(peeked_line.find(": ") != npos)
        {
            _line_progressed(peeked_line.find(": "));
            _c4err("': ' is not a valid token in plain flow (unquoted) scalars");
        }
        else if(peeked_line.ends_with(':'))
        {
            _line_progressed(peeked_line.find(':'));
            _c4err("lines cannot end with ':' in plain flow (unquoted) scalars");
        }
        else if((token_pos = peeked_line.find(" #")) != npos)
        {
            _line_progressed(token_pos);
            break;
            //_c4err("' #' is not a valid token in plain flow (unquoted) scalars");
        }

        _c4dbgpf("rscalar[IMPL]: append another line: (len={})'{}'", peeked_line.len, peeked_line.trimr("\r\n"));
        if(!_advance_to_peeked())
        {
            _c4dbgp("rscalar[IMPL]: file finishes after the scalar");
            break;
        }
        peeked_line = m_state->line_contents.rem;
    }
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_state->pos.offset >= offs);
    substr full(m_buf.str + (currscalar.str - m_buf.str),
                currscalar.len + (m_state->pos.offset - offs));
    full = full.trimr("\r\n ");
    return full;
}

substr Parser::_scan_complex_key(csubstr currscalar, csubstr peeked_line)
{
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_buf.is_super(currscalar));
    // NOTE. there's a problem with _scan_to_next_nonempty_line(), as it counts newlines twice
    // size_t offs = m_state->pos.offset;   // so we workaround by directly counting from the end of the given scalar
    _RYML_CB_ASSERT(m_stack.m_callbacks, currscalar.end() >= m_buf.begin());
    size_t offs = static_cast<size_t>(currscalar.end() - m_buf.begin());
    while(true)
    {
        _c4dbgp("rcplxkey: continuing...");
        if(peeked_line.begins_with("...") || peeked_line.begins_with("---"))
        {
            _c4dbgpf("rcplxkey: document termination next -- bail now '{}'", peeked_line.trimr("\r\n"));
            break;
        }
        else
        {
            size_t pos = peeked_line.first_of("?:[]{}");
            if(pos == csubstr::npos)
            {
                pos = peeked_line.find("- ");
            }
            if(pos != csubstr::npos)
            {
                _c4dbgpf("rcplxkey: found special characters at pos={}: '{}'", pos, peeked_line.trimr("\r\n"));
                _line_progressed(pos);
                break;
            }
        }

        _c4dbgpf("rcplxkey: no special chars found '{}'", peeked_line.trimr("\r\n"));
        csubstr next_peeked = _scan_to_next_nonempty_line(0);
        if(next_peeked.empty())
        {
            _c4dbgp("rcplxkey: empty ... finished.");
            break;
        }
        _c4dbgp("rcplxkey: ... continuing.");
        peeked_line = next_peeked;

        _c4dbgpf("rcplxkey: line contents: '{}'", peeked_line.trimr("\r\n"));
        size_t colpos;
        if((colpos = peeked_line.find(": ")) != npos)
        {
            _c4dbgp("rcplxkey: found ': ', stopping.");
            _line_progressed(colpos);
            break;
        }
        #ifdef RYML_NO_COVERAGE__TO_BE_DELETED
        else if((colpos = peeked_line.ends_with(':')))
        {
            _c4dbgp("rcplxkey: ends with ':', stopping.");
            _line_progressed(colpos);
            break;
        }
        #endif
        _c4dbgpf("rcplxkey: append another line: (len={})'{}'", peeked_line.len, peeked_line.trimr("\r\n"));
        if(!_advance_to_peeked())
        {
            _c4dbgp("rcplxkey: file finishes after the scalar");
            break;
        }
        peeked_line = m_state->line_contents.rem;
    }
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_state->pos.offset >= offs);
    substr full(m_buf.str + (currscalar.str - m_buf.str),
                currscalar.len + (m_state->pos.offset - offs));
    return full;
}

//! scans to the next non-blank line starting with the given indentation
csubstr Parser::_scan_to_next_nonempty_line(size_t indentation)
{
    csubstr next_peeked;
    while(true)
    {
        _c4dbgpf("rscalar: ... curr offset: {} indentation={}", m_state->pos.offset, indentation);
        next_peeked = _peek_next_line(m_state->pos.offset);
        csubstr next_peeked_triml = next_peeked.triml(' ');
        _c4dbgpf("rscalar: ... next peeked line='{}'", next_peeked.trimr("\r\n"));
        if(next_peeked_triml.begins_with('#'))
        {
            _c4dbgp("rscalar: ... first non-space character is #");
            return {};
        }
        else if(next_peeked.begins_with(' ', indentation))
        {
            _c4dbgpf("rscalar: ... begins at same indentation {}, assuming continuation", indentation);
            _advance_to_peeked();
            return next_peeked;
        }
        else   // check for de-indentation
        {
            csubstr trimmed = next_peeked_triml.trimr("\t\r\n");
            _c4dbgpf("rscalar: ... deindented! trimmed='{}'", trimmed);
            if(!trimmed.empty())
            {
                _c4dbgp("rscalar: ... and not empty. bailing out.");
                return {};
            }
        }
        if(!_advance_to_peeked())
        {
            _c4dbgp("rscalar: file finished");
            return {};
        }
    }
    return {};
}

// returns false when the file finished
bool Parser::_advance_to_peeked()
{
    _line_progressed(m_state->line_contents.rem.len);
    _line_ended(); // advances to the peeked-at line, consuming all remaining (probably newline) characters on the current line
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_state->line_contents.rem.first_of("\r\n") == csubstr::npos);
    _c4dbgpf("advance to peeked: scan more... pos={} len={}", m_state->pos.offset, m_buf.len);
    _scan_line();  // puts the peeked-at line in the buffer
    if(_finished_file())
    {
        _c4dbgp("rscalar: finished file!");
        return false;
    }
    return true;
}

//-----------------------------------------------------------------------------

C4_ALWAYS_INLINE size_t _extend_from_combined_newline(char nl, char following)
{
    return (nl == '\n' && following == '\r') || (nl == '\r' && following == '\n');
}

//! look for the next newline chars, and jump to the right of those
csubstr from_next_line(csubstr rem)
{
    size_t nlpos = rem.first_of("\r\n");
    if(nlpos == csubstr::npos)
        return {};
    const char nl = rem[nlpos];
    rem = rem.right_of(nlpos);
    if(rem.empty())
        return {};
    if(_extend_from_combined_newline(nl, rem.front()))
        rem = rem.sub(1);
    return rem;
}

csubstr Parser::_peek_next_line(size_t pos) const
{
    csubstr rem{}; // declare here because of the goto
    size_t nlpos{}; // declare here because of the goto
    pos = pos == npos ? m_state->pos.offset : pos;
    if(pos >= m_buf.len)
        goto next_is_empty;

    // look for the next newline chars, and jump to the right of those
    rem = from_next_line(m_buf.sub(pos));
    if(rem.empty())
        goto next_is_empty;

    // now get everything up to and including the following newline chars
    nlpos = rem.first_of("\r\n");
    if((nlpos != csubstr::npos) && (nlpos + 1 < rem.len))
        nlpos += _extend_from_combined_newline(rem[nlpos], rem[nlpos+1]);
    rem = rem.left_of(nlpos, /*include_pos*/true);

    _c4dbgpf("peek next line @ {}: (len={})'{}'", pos, rem.len, rem.trimr("\r\n"));
    return rem;

next_is_empty:
    _c4dbgpf("peek next line @ {}: (len=0)''", pos);
    return {};
}


//-----------------------------------------------------------------------------
void Parser::LineContents::reset_with_next_line(csubstr buf, size_t offset)
{
    RYML_ASSERT(offset <= buf.len);
    char const* C4_RESTRICT b = &buf[offset];
    char const* C4_RESTRICT e = b;
    // get the current line stripped of newline chars
    while(e < buf.end() && (*e != '\n' && *e != '\r'))
        ++e;
    RYML_ASSERT(e >= b);
    const csubstr stripped_ = buf.sub(offset, static_cast<size_t>(e - b));
    // advance pos to include the first line ending
    if(e != buf.end() && *e == '\r')
        ++e;
    if(e != buf.end() && *e == '\n')
        ++e;
    RYML_ASSERT(e >= b);
    const csubstr full_ = buf.sub(offset, static_cast<size_t>(e - b));
    reset(full_, stripped_);
}

void Parser::_scan_line()
{
    if(m_state->pos.offset >= m_buf.len)
    {
        m_state->line_contents.reset(m_buf.last(0), m_buf.last(0));
        return;
    }
    m_state->line_contents.reset_with_next_line(m_buf, m_state->pos.offset);
}


//-----------------------------------------------------------------------------
void Parser::_line_progressed(size_t ahead)
{
    _c4dbgpf("line[{}] ({} cols) progressed by {}:  col {}-->{}   offset {}-->{}", m_state->pos.line, m_state->line_contents.full.len, ahead, m_state->pos.col, m_state->pos.col+ahead, m_state->pos.offset, m_state->pos.offset+ahead);
    m_state->pos.offset += ahead;
    m_state->pos.col += ahead;
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_state->pos.col <= m_state->line_contents.stripped.len+1);
    m_state->line_contents.rem = m_state->line_contents.rem.sub(ahead);
}

void Parser::_line_ended()
{
    _c4dbgpf("line[{}] ({} cols) ended! offset {}-->{}", m_state->pos.line, m_state->line_contents.full.len, m_state->pos.offset, m_state->pos.offset+m_state->line_contents.full.len - m_state->line_contents.stripped.len);
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_state->pos.col == m_state->line_contents.stripped.len+1);
    m_state->pos.offset += m_state->line_contents.full.len - m_state->line_contents.stripped.len;
    ++m_state->pos.line;
    m_state->pos.col = 1;
}

void Parser::_line_ended_undo()
{
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_state->pos.col == 1u);
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_state->pos.line > 0u);
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_state->pos.offset >= m_state->line_contents.full.len - m_state->line_contents.stripped.len);
    size_t delta = m_state->line_contents.full.len - m_state->line_contents.stripped.len;
    _c4dbgpf("line[{}] undo ended! line {}-->{}, offset {}-->{}", m_state->pos.line, m_state->pos.line, m_state->pos.line - 1, m_state->pos.offset, m_state->pos.offset - delta);
    m_state->pos.offset -= delta;
    --m_state->pos.line;
    m_state->pos.col = m_state->line_contents.stripped.len + 1u;
    // don't forget to undo also the changes to the remainder of the line
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_state->pos.offset >= m_buf.len || m_buf[m_state->pos.offset] == '\n' || m_buf[m_state->pos.offset] == '\r');
    m_state->line_contents.rem = m_buf.sub(m_state->pos.offset, 0);
}


//-----------------------------------------------------------------------------
void Parser::_set_indentation(size_t indentation)
{
    m_state->indref = indentation;
    _c4dbgpf("state[{}]: saving indentation: {}", m_state-m_stack.begin(), m_state->indref);
}

void Parser::_save_indentation(size_t behind)
{
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_state->line_contents.rem.begin() >= m_state->line_contents.full.begin());
    m_state->indref = static_cast<size_t>(m_state->line_contents.rem.begin() - m_state->line_contents.full.begin());
    _RYML_CB_ASSERT(m_stack.m_callbacks, behind <= m_state->indref);
    m_state->indref -= behind;
    _c4dbgpf("state[{}]: saving indentation: {}", m_state-m_stack.begin(), m_state->indref);
}

bool Parser::_maybe_set_indentation_from_anchor_or_tag()
{
    if(m_key_anchor.not_empty())
    {
        _c4dbgpf("set indentation from key anchor: {}", m_key_anchor_indentation);
        _set_indentation(m_key_anchor_indentation); // this is the column where the anchor starts
        return true;
    }
    else if(m_key_tag.not_empty())
    {
        _c4dbgpf("set indentation from key tag: {}", m_key_tag_indentation);
        _set_indentation(m_key_tag_indentation); // this is the column where the tag starts
        return true;
    }
    return false;
}


//-----------------------------------------------------------------------------
void Parser::_write_key_anchor(size_t node_id)
{
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_tree->has_key(node_id));
    if( ! m_key_anchor.empty())
    {
        _c4dbgpf("node={}: set key anchor to '{}'", node_id, m_key_anchor);
        m_tree->set_key_anchor(node_id, m_key_anchor);
        m_key_anchor.clear();
        m_key_anchor_was_before = false;
        m_key_anchor_indentation = 0;
    }
    else if( ! m_tree->is_key_quoted(node_id))
    {
        csubstr r = m_tree->key(node_id);
        if(r.begins_with('*'))
        {
            _c4dbgpf("node={}: set key reference: '{}'", node_id, r);
            m_tree->set_key_ref(node_id, r.sub(1));
        }
        else if(r == "<<")
        {
            m_tree->set_key_ref(node_id, r);
            _c4dbgpf("node={}: it's an inheriting reference", node_id);
            if(m_tree->is_seq(node_id))
            {
                _c4dbgpf("node={}: inheriting from seq of {}", node_id, m_tree->num_children(node_id));
                for(size_t i = m_tree->first_child(node_id); i != NONE; i = m_tree->next_sibling(i))
                {
                    if( ! (m_tree->val(i).begins_with('*')))
                        _c4err("malformed reference: '{}'", m_tree->val(i));
                }
            }
            else if( ! m_tree->val(node_id).begins_with('*'))
            {
                 _c4err("malformed reference: '{}'", m_tree->val(node_id));
            }
            //m_tree->set_key_ref(node_id, r);
        }
    }
}

//-----------------------------------------------------------------------------
void Parser::_write_val_anchor(size_t node_id)
{
    if( ! m_val_anchor.empty())
    {
        _c4dbgpf("node={}: set val anchor to '{}'", node_id, m_val_anchor);
        m_tree->set_val_anchor(node_id, m_val_anchor);
        m_val_anchor.clear();
    }
    csubstr r = m_tree->has_val(node_id) ? m_tree->val(node_id) : "";
    if(!m_tree->is_val_quoted(node_id) && r.begins_with('*'))
    {
        _c4dbgpf("node={}: set val reference: '{}'", node_id, r);
        RYML_CHECK(!m_tree->has_val_anchor(node_id));
        m_tree->set_val_ref(node_id, r.sub(1));
    }
}

//-----------------------------------------------------------------------------
void Parser::_push_level(bool explicit_flow_chars)
{
    _c4dbgpf("pushing level! currnode={}  currlevel={} stacksize={} stackcap={}", m_state->node_id, m_state->level, m_stack.size(), m_stack.capacity());
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_state == &m_stack.top());
    if(node(m_state) == nullptr)
    {
        _c4dbgp("pushing level! actually no, current node is null");
        //_RYML_CB_ASSERT(m_stack.m_callbacks,  ! explicit_flow_chars);
        return;
    }
    flag_t st = RUNK;
    if(explicit_flow_chars || has_all(FLOW))
    {
        st |= FLOW;
    }
    m_stack.push_top();
    m_state = &m_stack.top();
    set_flags(st);
    m_state->node_id = (size_t)NONE;
    m_state->indref = (size_t)NONE;
    ++m_state->level;
    _c4dbgpf("pushing level: now, currlevel={}", m_state->level);
}

void Parser::_pop_level()
{
    _c4dbgpf("popping level! currnode={} currlevel={}", m_state->node_id, m_state->level);
    if(has_any(RMAP) || m_tree->is_map(m_state->node_id))
    {
        _stop_map();
    }
    if(has_any(RSEQ) || m_tree->is_seq(m_state->node_id))
    {
        _stop_seq();
    }
    if(m_tree->is_doc(m_state->node_id))
    {
        _stop_doc();
    }
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_stack.size() > 1);
    _prepare_pop();
    m_stack.pop();
    m_state = &m_stack.top();
    /*if(has_any(RMAP))
    {
        _toggle_key_val();
    }*/
    if(m_state->line_contents.indentation == 0)
    {
        //_RYML_CB_ASSERT(m_stack.m_callbacks, has_none(RTOP));
        add_flags(RTOP);
    }
    _c4dbgpf("popping level: now, currnode={} currlevel={}", m_state->node_id, m_state->level);
}

//-----------------------------------------------------------------------------
void Parser::_start_unk(bool /*as_child*/)
{
    _c4dbgp("start_unk");
    _push_level();
    _move_scalar_from_top();
}

//-----------------------------------------------------------------------------
void Parser::_start_doc(bool as_child)
{
    _c4dbgpf("start_doc (as child={})", as_child);
    _RYML_CB_ASSERT(m_stack.m_callbacks, node(m_stack.bottom()) == node(m_root_id));
    size_t parent_id = m_stack.size() < 2 ? m_root_id : m_stack.top(1).node_id;
    _RYML_CB_ASSERT(m_stack.m_callbacks, parent_id != NONE);
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_tree->is_root(parent_id));
    _RYML_CB_ASSERT(m_stack.m_callbacks, node(m_state) == nullptr || node(m_state) == node(m_root_id));
    if(as_child)
    {
        _c4dbgpf("start_doc: parent={}", parent_id);
        if( ! m_tree->is_stream(parent_id))
        {
            _c4dbgp("start_doc: rearranging with root as STREAM");
            m_tree->set_root_as_stream();
        }
        m_state->node_id = m_tree->append_child(parent_id);
        m_tree->to_doc(m_state->node_id);
    }
    #ifdef RYML_NO_COVERAGE__TO_BE_DELETED
    else
    {
        _RYML_CB_ASSERT(m_stack.m_callbacks, m_tree->is_seq(parent_id) || m_tree->empty(parent_id));
        m_state->node_id = parent_id;
        if( ! m_tree->is_doc(parent_id))
        {
            m_tree->to_doc(parent_id, DOC);
        }
    }
    #endif
    _c4dbgpf("start_doc: id={}", m_state->node_id);
    add_flags(RUNK|RTOP|NDOC);
    _handle_types();
    rem_flags(NDOC);
}

void Parser::_stop_doc()
{
    size_t doc_node = m_state->node_id;
    _c4dbgpf("stop_doc[{}]", doc_node);
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_tree->is_doc(doc_node));
    if(!m_tree->is_seq(doc_node) && !m_tree->is_map(doc_node) && !m_tree->is_val(doc_node))
    {
        _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(SSCL));
        _c4dbgpf("stop_doc[{}]: there was nothing; adding null val", doc_node);
        m_tree->to_val(doc_node, {}, DOC);
    }
}

void Parser::_end_stream()
{
    _c4dbgpf("end_stream, level={} node_id={}", m_state->level, m_state->node_id);
    _RYML_CB_ASSERT(m_stack.m_callbacks,  ! m_stack.empty());
    NodeData *added = nullptr;
    if(has_any(SSCL))
    {
        if(m_tree->is_seq(m_state->node_id))
        {
            _c4dbgp("append val...");
            added = _append_val(_consume_scalar());
        }
        else if(m_tree->is_map(m_state->node_id))
        {
            _c4dbgp("append null key val...");
            added = _append_key_val_null(m_state->line_contents.rem.str);
            #ifdef RYML_NO_COVERAGE__TO_BE_DELETED
            if(has_any(RSEQIMAP))
            {
                _stop_seqimap();
                _pop_level();
            }
            #endif
        }
        else if(m_tree->is_doc(m_state->node_id) || m_tree->type(m_state->node_id) == NOTYPE)
        {
            NodeType_e quoted = has_any(QSCL) ? VALQUO : NOTYPE; // do this before consuming the scalar
            csubstr scalar = _consume_scalar();
            _c4dbgpf("node[{}]: to docval '{}'{}", m_state->node_id, scalar, quoted == VALQUO ? ", quoted" : "");
            m_tree->to_val(m_state->node_id, scalar, DOC|quoted);
            added = m_tree->get(m_state->node_id);
        }
        else
        {
            _c4err("internal error");
        }
    }
    else if(has_all(RSEQ|RVAL) && has_none(FLOW))
    {
        _c4dbgp("add last...");
        added = _append_val_null(m_state->line_contents.rem.str);
    }
    else if(!m_val_tag.empty() && (m_tree->is_doc(m_state->node_id) || m_tree->type(m_state->node_id) == NOTYPE))
    {
        csubstr scalar = m_state->line_contents.rem.first(0);
        _c4dbgpf("node[{}]: add null scalar as docval", m_state->node_id);
        m_tree->to_val(m_state->node_id, scalar, DOC);
        added = m_tree->get(m_state->node_id);
    }

    if(added)
    {
        size_t added_id = m_tree->id(added);
        if(m_tree->is_seq(m_state->node_id) || m_tree->is_doc(m_state->node_id))
        {
            if(!m_key_anchor.empty())
            {
                _c4dbgpf("node[{}]: move key to val anchor: '{}'", added_id, m_key_anchor);
                m_val_anchor = m_key_anchor;
                m_key_anchor = {};
            }
            if(!m_key_tag.empty())
            {
                _c4dbgpf("node[{}]: move key to val tag: '{}'", added_id, m_key_tag);
                m_val_tag = m_key_tag;
                m_key_tag = {};
            }
        }
        #ifdef RYML_NO_COVERAGE__TO_BE_DELETED
        if(!m_key_anchor.empty())
        {
            _c4dbgpf("node[{}]: set key anchor='{}'", added_id, m_key_anchor);
            m_tree->set_key_anchor(added_id, m_key_anchor);
            m_key_anchor = {};
        }
        #endif
        if(!m_val_anchor.empty())
        {
            _c4dbgpf("node[{}]: set val anchor='{}'", added_id, m_val_anchor);
            m_tree->set_val_anchor(added_id, m_val_anchor);
            m_val_anchor = {};
        }
        #ifdef RYML_NO_COVERAGE__TO_BE_DELETED
        if(!m_key_tag.empty())
        {
            _c4dbgpf("node[{}]: set key tag='{}' -> '{}'", added_id, m_key_tag, normalize_tag(m_key_tag));
            m_tree->set_key_tag(added_id, normalize_tag(m_key_tag));
            m_key_tag = {};
        }
        #endif
        if(!m_val_tag.empty())
        {
            _c4dbgpf("node[{}]: set val tag='{}' -> '{}'", added_id, m_val_tag, normalize_tag(m_val_tag));
            m_tree->set_val_tag(added_id, normalize_tag(m_val_tag));
            m_val_tag = {};
        }
    }

    while(m_stack.size() > 1)
    {
        _c4dbgpf("popping level: {} (stack sz={})", m_state->level, m_stack.size());
        _RYML_CB_ASSERT(m_stack.m_callbacks,  ! has_any(SSCL, &m_stack.top()));
        if(has_all(RSEQ|FLOW))
            _err("closing ] not found");
        _pop_level();
    }
    add_flags(NDOC);
}

void Parser::_start_new_doc(csubstr rem)
{
    _c4dbgp("_start_new_doc");
    _RYML_CB_ASSERT(m_stack.m_callbacks, rem.begins_with("---"));
    C4_UNUSED(rem);

    _end_stream();

    size_t indref = m_state->indref;
    _c4dbgpf("start a document, indentation={}", indref);
    _line_progressed(3);
    _push_level();
    _start_doc();
    _set_indentation(indref);
}


//-----------------------------------------------------------------------------
void Parser::_start_map(bool as_child)
{
    _c4dbgpf("start_map (as child={})", as_child);
    addrem_flags(RMAP|RVAL, RKEY|RUNK);
    _RYML_CB_ASSERT(m_stack.m_callbacks, node(m_stack.bottom()) == node(m_root_id));
    size_t parent_id = m_stack.size() < 2 ? m_root_id : m_stack.top(1).node_id;
    _RYML_CB_ASSERT(m_stack.m_callbacks, parent_id != NONE);
    _RYML_CB_ASSERT(m_stack.m_callbacks, node(m_state) == nullptr || node(m_state) == node(m_root_id));
    if(as_child)
    {
        m_state->node_id = m_tree->append_child(parent_id);
        if(has_all(SSCL))
        {
            type_bits key_quoted = NOTYPE;
            if(m_state->flags & QSCL) // before consuming the scalar
                key_quoted |= KEYQUO;
            csubstr key = _consume_scalar();
            m_tree->to_map(m_state->node_id, key, key_quoted);
            _c4dbgpf("start_map: id={} key='{}'", m_state->node_id, m_tree->key(m_state->node_id));
            _write_key_anchor(m_state->node_id);
            if( ! m_key_tag.empty())
            {
                _c4dbgpf("node[{}]: set key tag='{}' -> '{}'", m_state->node_id, m_key_tag, normalize_tag(m_key_tag));
                m_tree->set_key_tag(m_state->node_id, normalize_tag(m_key_tag));
                m_key_tag.clear();
            }
        }
        else
        {
            m_tree->to_map(m_state->node_id);
            _c4dbgpf("start_map: id={}", m_state->node_id);
        }
        m_tree->_p(m_state->node_id)->m_val.scalar.str = m_state->line_contents.rem.str;
        _write_val_anchor(m_state->node_id);
    }
    else
    {
        _RYML_CB_ASSERT(m_stack.m_callbacks, parent_id != NONE);
        m_state->node_id = parent_id;
        _c4dbgpf("start_map: id={}", m_state->node_id);
        type_bits as_doc = 0;
        if(m_tree->is_doc(m_state->node_id))
            as_doc |= DOC;
        if(!m_tree->is_map(parent_id))
        {
            RYML_CHECK(!m_tree->has_children(parent_id));
            m_tree->to_map(parent_id, as_doc);
        }
        else
        {
            m_tree->_add_flags(parent_id, as_doc);
        }
        _move_scalar_from_top();
        if(m_key_anchor.not_empty())
            m_key_anchor_was_before = true;
        _write_val_anchor(parent_id);
        if(m_stack.size() >= 2)
        {
            State const& parent_state = m_stack.top(1);
            if(parent_state.flags & RSET)
                add_flags(RSET);
        }
        m_tree->_p(parent_id)->m_val.scalar.str = m_state->line_contents.rem.str;
    }
    if( ! m_val_tag.empty())
    {
        _c4dbgpf("node[{}]: set val tag='{}' -> '{}'", m_state->node_id, m_val_tag, normalize_tag(m_val_tag));
        m_tree->set_val_tag(m_state->node_id, normalize_tag(m_val_tag));
        m_val_tag.clear();
    }
}

void Parser::_start_map_unk(bool as_child)
{
    if(!m_key_anchor_was_before)
    {
        _c4dbgpf("stash key anchor before starting map... '{}'", m_key_anchor);
        csubstr ka = m_key_anchor;
        m_key_anchor = {};
        _start_map(as_child);
        m_key_anchor = ka;
    }
    else
    {
        _start_map(as_child);
        m_key_anchor_was_before = false;
    }
    if(m_key_tag2.not_empty())
    {
        m_key_tag = m_key_tag2;
        m_key_tag_indentation = m_key_tag2_indentation;
        m_key_tag2.clear();
        m_key_tag2_indentation = 0;
    }
}

void Parser::_stop_map()
{
    _c4dbgpf("stop_map[{}]", m_state->node_id);
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_tree->is_map(m_state->node_id));
    if(has_all(QMRK|RKEY) && !has_all(SSCL))
    {
        _c4dbgpf("stop_map[{}]: RKEY", m_state->node_id);
        _store_scalar_null(m_state->line_contents.rem.str);
        _append_key_val_null(m_state->line_contents.rem.str);
    }
}


//-----------------------------------------------------------------------------
void Parser::_start_seq(bool as_child)
{
    _c4dbgpf("start_seq (as child={})", as_child);
    if(has_all(RTOP|RUNK))
    {
        _c4dbgpf("start_seq: moving key tag to val tag: '{}'", m_key_tag);
        m_val_tag = m_key_tag;
        m_key_tag.clear();
    }
    addrem_flags(RSEQ|RVAL, RUNK);
    _RYML_CB_ASSERT(m_stack.m_callbacks, node(m_stack.bottom()) == node(m_root_id));
    size_t parent_id = m_stack.size() < 2 ? m_root_id : m_stack.top(1).node_id;
    _RYML_CB_ASSERT(m_stack.m_callbacks, parent_id != NONE);
    _RYML_CB_ASSERT(m_stack.m_callbacks, node(m_state) == nullptr || node(m_state) == node(m_root_id));
    if(as_child)
    {
        m_state->node_id = m_tree->append_child(parent_id);
        if(has_all(SSCL))
        {
            _RYML_CB_ASSERT(m_stack.m_callbacks, m_tree->is_map(parent_id));
            type_bits key_quoted = 0;
            if(m_state->flags & QSCL) // before consuming the scalar
                key_quoted |= KEYQUO;
            csubstr key = _consume_scalar();
            m_tree->to_seq(m_state->node_id, key, key_quoted);
            _c4dbgpf("start_seq: id={} name='{}'", m_state->node_id, m_tree->key(m_state->node_id));
            _write_key_anchor(m_state->node_id);
            if( ! m_key_tag.empty())
            {
                _c4dbgpf("start_seq[{}]: set key tag='{}' -> '{}'", m_state->node_id, m_key_tag, normalize_tag(m_key_tag));
                m_tree->set_key_tag(m_state->node_id, normalize_tag(m_key_tag));
                m_key_tag.clear();
            }
        }
        else
        {
            type_bits as_doc = 0;
            _RYML_CB_ASSERT(m_stack.m_callbacks, !m_tree->is_doc(m_state->node_id));
            m_tree->to_seq(m_state->node_id, as_doc);
            _c4dbgpf("start_seq: id={}{}", m_state->node_id, as_doc ? " as doc" : "");
        }
        _write_val_anchor(m_state->node_id);
        m_tree->_p(m_state->node_id)->m_val.scalar.str = m_state->line_contents.rem.str;
    }
    else
    {
        m_state->node_id = parent_id;
        type_bits as_doc = 0;
        if(m_tree->is_doc(m_state->node_id))
            as_doc |= DOC;
        if(!m_tree->is_seq(parent_id))
        {
            RYML_CHECK(!m_tree->has_children(parent_id));
            m_tree->to_seq(parent_id, as_doc);
        }
        else
        {
            m_tree->_add_flags(parent_id, as_doc);
        }
        _move_scalar_from_top();
        _c4dbgpf("start_seq: id={}{}", m_state->node_id, as_doc ? " as_doc" : "");
        _write_val_anchor(parent_id);
        m_tree->_p(parent_id)->m_val.scalar.str = m_state->line_contents.rem.str;
    }
    if( ! m_val_tag.empty())
    {
        _c4dbgpf("start_seq[{}]: set val tag='{}' -> '{}'", m_state->node_id, m_val_tag, normalize_tag(m_val_tag));
        m_tree->set_val_tag(m_state->node_id, normalize_tag(m_val_tag));
        m_val_tag.clear();
    }
}

void Parser::_stop_seq()
{
    _c4dbgp("stop_seq");
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_tree->is_seq(m_state->node_id));
}


//-----------------------------------------------------------------------------
void Parser::_start_seqimap()
{
    _c4dbgpf("start_seqimap at node={}. has_children={}", m_state->node_id, m_tree->has_children(m_state->node_id));
    _RYML_CB_ASSERT(m_stack.m_callbacks, has_all(RSEQ|FLOW));
    // create a map, and turn the last scalar of this sequence
    // into the key of the map's first child. This scalar was
    // understood to be a value in the sequence, but it is
    // actually a key of a map, implicitly opened here.
    // Eg [val, key: val]
    //
    // Yep, YAML is crazy.
    if(m_tree->has_children(m_state->node_id) && m_tree->has_val(m_tree->last_child(m_state->node_id)))
    {
        size_t prev = m_tree->last_child(m_state->node_id);
        NodeType ty = m_tree->_p(prev)->m_type; // don't use type() because it masks out the quotes
        NodeScalar tmp = m_tree->valsc(prev);
        _c4dbgpf("has children and last child={} has val. saving the scalars, val='{}' quoted={}", prev, tmp.scalar, ty.is_val_quoted());
        m_tree->remove(prev);
        _push_level();
        _start_map();
        _store_scalar(tmp.scalar, ty.is_val_quoted());
        m_key_anchor = tmp.anchor;
        m_key_tag = tmp.tag;
    }
    else
    {
        _c4dbgpf("node {} has no children yet, using empty key", m_state->node_id);
        _push_level();
        _start_map();
        _store_scalar_null(m_state->line_contents.rem.str);
    }
    add_flags(RSEQIMAP|FLOW);
}

void Parser::_stop_seqimap()
{
    _c4dbgp("stop_seqimap");
    _RYML_CB_ASSERT(m_stack.m_callbacks, has_all(RSEQIMAP));
}


//-----------------------------------------------------------------------------
NodeData* Parser::_append_val(csubstr val, flag_t quoted)
{
    _RYML_CB_ASSERT(m_stack.m_callbacks,  ! has_all(SSCL));
    _RYML_CB_ASSERT(m_stack.m_callbacks, node(m_state) != nullptr);
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_tree->is_seq(m_state->node_id));
    type_bits additional_flags = quoted ? VALQUO : NOTYPE;
    _c4dbgpf("append val: '{}' to parent id={} (level={}){}", val, m_state->node_id, m_state->level, quoted ? " VALQUO!" : "");
    size_t nid = m_tree->append_child(m_state->node_id);
    m_tree->to_val(nid, val, additional_flags);

    _c4dbgpf("append val: id={} val='{}'", nid, m_tree->get(nid)->m_val.scalar);
    if( ! m_val_tag.empty())
    {
        _c4dbgpf("append val[{}]: set val tag='{}' -> '{}'", nid, m_val_tag, normalize_tag(m_val_tag));
        m_tree->set_val_tag(nid, normalize_tag(m_val_tag));
        m_val_tag.clear();
    }
    _write_val_anchor(nid);
    return m_tree->get(nid);
}

NodeData* Parser::_append_key_val(csubstr val, flag_t val_quoted)
{
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_tree->is_map(m_state->node_id));
    type_bits additional_flags = 0;
    if(m_state->flags & QSCL)
        additional_flags |= KEYQUO;
    if(val_quoted)
        additional_flags |= VALQUO;

    csubstr key = _consume_scalar();
    _c4dbgpf("append keyval: '{}' '{}' to parent id={} (level={}){}{}", key, val, m_state->node_id, m_state->level, (additional_flags & KEYQUO) ? " KEYQUO!" : "", (additional_flags & VALQUO) ? " VALQUO!" : "");
    size_t nid = m_tree->append_child(m_state->node_id);
    m_tree->to_keyval(nid, key, val, additional_flags);
    _c4dbgpf("append keyval: id={} key='{}' val='{}'", nid, m_tree->key(nid), m_tree->val(nid));
    if( ! m_key_tag.empty())
    {
        _c4dbgpf("append keyval[{}]: set key tag='{}' -> '{}'", nid, m_key_tag, normalize_tag(m_key_tag));
        m_tree->set_key_tag(nid, normalize_tag(m_key_tag));
        m_key_tag.clear();
    }
    if( ! m_val_tag.empty())
    {
        _c4dbgpf("append keyval[{}]: set val tag='{}' -> '{}'", nid, m_val_tag, normalize_tag(m_val_tag));
        m_tree->set_val_tag(nid, normalize_tag(m_val_tag));
        m_val_tag.clear();
    }
    _write_key_anchor(nid);
    _write_val_anchor(nid);
    rem_flags(QMRK);
    return m_tree->get(nid);
}


//-----------------------------------------------------------------------------
void Parser::_store_scalar(csubstr s, flag_t is_quoted)
{
    _c4dbgpf("state[{}]: storing scalar '{}' (flag: {}) (old scalar='{}')",
             m_state-m_stack.begin(), s, m_state->flags & SSCL, m_state->scalar);
    RYML_CHECK(has_none(SSCL));
    add_flags(SSCL | (is_quoted * QSCL));
    m_state->scalar = s;
}

csubstr Parser::_consume_scalar()
{
    _c4dbgpf("state[{}]: consuming scalar '{}' (flag: {}))", m_state-m_stack.begin(), m_state->scalar, m_state->flags & SSCL);
    RYML_CHECK(m_state->flags & SSCL);
    csubstr s = m_state->scalar;
    rem_flags(SSCL | QSCL);
    m_state->scalar.clear();
    return s;
}

void Parser::_move_scalar_from_top()
{
    if(m_stack.size() < 2) return;
    State &prev = m_stack.top(1);
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_state == &m_stack.top());
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_state != &prev);
    if(prev.flags & SSCL)
    {
        _c4dbgpf("moving scalar '{}' from state[{}] to state[{}] (overwriting '{}')", prev.scalar, &prev-m_stack.begin(), m_state-m_stack.begin(), m_state->scalar);
        add_flags(prev.flags & (SSCL | QSCL));
        m_state->scalar = prev.scalar;
        rem_flags(SSCL | QSCL, &prev);
        prev.scalar.clear();
    }
}

//-----------------------------------------------------------------------------
/** @todo this function is a monster and needs love. Likely, it needs
 * to be split like _scan_scalar_*() */
bool Parser::_handle_indentation()
{
    _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(FLOW));
    if( ! _at_line_begin())
        return false;

    size_t ind = m_state->line_contents.indentation;
    csubstr rem = m_state->line_contents.rem;
    /** @todo instead of trimming, we should use the indentation index from above */
    csubstr remt = rem.triml(' ');

    if(remt.empty() || remt.begins_with('#')) // this is a blank or comment line
    {
        _line_progressed(rem.size());
        return true;
    }

    _c4dbgpf("indentation? ind={} indref={}", ind, m_state->indref);
    if(ind == m_state->indref)
    {
        _c4dbgpf("same indentation: {}", ind);
        if(!rem.sub(ind).begins_with('-'))
        {
            _c4dbgp("does not begin with -");
            if(has_any(RMAP))
            {
                if(has_all(SSCL|RVAL))
                {
                    _c4dbgp("add with null val");
                    _append_key_val_null(rem.str + ind - 1);
                    addrem_flags(RKEY, RVAL);
                }
            }
            else if(has_any(RSEQ))
            {
                if(m_stack.size() > 2) // do not pop to root level
                {
                    if(has_any(RNXT))
                    {
                        _c4dbgp("end the indentless seq");
                        _pop_level();
                        return true;
                    }
                    else if(has_any(RVAL))
                    {
                        _c4dbgp("add with null val");
                        _append_val_null(rem.str);
                        _c4dbgp("end the indentless seq");
                        _pop_level();
                        return true;
                    }
                }
            }
        }
        _line_progressed(ind);
        return ind > 0;
    }
    else if(ind < m_state->indref)
    {
        _c4dbgpf("smaller indentation ({} < {})!!!", ind, m_state->indref);
        if(has_all(RVAL))
        {
            _c4dbgp("there was an empty val -- appending");
            if(has_all(RMAP))
            {
                _RYML_CB_ASSERT(m_stack.m_callbacks, has_all(SSCL));
                _append_key_val_null(rem.sub(ind).str - 1);
            }
            else if(has_all(RSEQ))
            {
                _RYML_CB_ASSERT(m_stack.m_callbacks, has_none(SSCL));
                _append_val_null(rem.sub(ind).str - 1);
            }
        }
        // search the stack frame to jump to based on its indentation
        State const* popto = nullptr;
        _RYML_CB_ASSERT(m_stack.m_callbacks, m_stack.is_contiguous()); // this search relies on the stack being contiguous
        for(State const* s = m_state-1; s >= m_stack.begin(); --s)
        {
            _c4dbgpf("searching for state with indentation {}. curr={} (level={},node={})", ind, s->indref, s->level, s->node_id);
            if(s->indref == ind)
            {
                _c4dbgpf("gotit!!! level={} node={}", s->level, s->node_id);
                popto = s;
                // while it may be tempting to think we're done at this
                // point, we must still determine whether we're jumping to a
                // parent with the same indentation. Consider this case with
                // an indentless sequence:
                //
                // product:
                // - sku: BL394D
                //   quantity: 4
                //   description: Basketball
                //   price: 450.00
                // - sku: BL4438H
                //   quantity: 1
                //   description: Super Hoop
                //   price: 2392.00  # jumping one level here would be wrong.
                // tax: 1234.5       # we must jump two levels
                if(popto > m_stack.begin())
                {
                    auto parent = popto - 1;
                    if(parent->indref == popto->indref)
                    {
                        _c4dbgpf("the parent (level={},node={}) has the same indentation ({}). is this in an indentless sequence?", parent->level, parent->node_id, popto->indref);
                        _c4dbgpf("isseq(popto)={} ismap(parent)={}", m_tree->is_seq(popto->node_id), m_tree->is_map(parent->node_id));
                        if(m_tree->is_seq(popto->node_id) && m_tree->is_map(parent->node_id))
                        {
                            if( ! remt.begins_with('-'))
                            {
                                _c4dbgp("this is an indentless sequence");
                                popto = parent;
                            }
                            else
                            {
                                _c4dbgp("not an indentless sequence");
                            }
                        }
                    }
                }
                break;
            }
        }
        if(!popto || popto >= m_state || popto->level >= m_state->level)
        {
            _c4err("parse error: incorrect indentation?");
        }
        _c4dbgpf("popping {} levels: from level {} to level {}", m_state->level-popto->level, m_state->level, popto->level);
        while(m_state != popto)
        {
            _c4dbgpf("popping level {} (indentation={})", m_state->level, m_state->indref);
            _pop_level();
        }
        _RYML_CB_ASSERT(m_stack.m_callbacks, ind == m_state->indref);
        _line_progressed(ind);
        return true;
    }
    else
    {
        _c4dbgpf("larger indentation ({} > {})!!!", ind, m_state->indref);
        _RYML_CB_ASSERT(m_stack.m_callbacks, ind > m_state->indref);
        if(has_all(RMAP|RVAL))
        {
            if(_is_scalar_next__rmap_val(remt) && remt.first_of(":?") == npos)
            {
                _c4dbgpf("actually it seems a value: '{}'", remt);
            }
            else
            {
                addrem_flags(RKEY, RVAL);
                _start_unk();
                //_move_scalar_from_top();
                _line_progressed(ind);
                _save_indentation();
                return true;
            }
        }
        else if(has_all(RSEQ|RVAL))
        {
            // nothing to do here
        }
        else
        {
            _c4err("parse error - indentation should not increase at this point");
        }
    }

    return false;
}

//-----------------------------------------------------------------------------
csubstr Parser::_scan_comment()
{
    csubstr s = m_state->line_contents.rem;
    _RYML_CB_ASSERT(m_stack.m_callbacks, s.begins_with('#'));
    _line_progressed(s.len);
    // skip the # character
    s = s.sub(1);
    // skip leading whitespace
    s = s.right_of(s.first_not_of(' '), /*include_pos*/true);
    _c4dbgpf("comment was '{}'", s);
    return s;
}

//-----------------------------------------------------------------------------
csubstr Parser::_scan_squot_scalar()
{
    // quoted scalars can spread over multiple lines!
    // nice explanation here: http://yaml-multiline.info/

    // a span to the end of the file
    size_t b = m_state->pos.offset;
    substr s = m_buf.sub(b);
    if(s.begins_with(' '))
    {
        s = s.triml(' ');
        _RYML_CB_ASSERT(m_stack.m_callbacks, m_buf.sub(b).is_super(s));
        _RYML_CB_ASSERT(m_stack.m_callbacks, s.begin() >= m_buf.sub(b).begin());
        _line_progressed((size_t)(s.begin() - m_buf.sub(b).begin()));
    }
    b = m_state->pos.offset; // take this into account
    _RYML_CB_ASSERT(m_stack.m_callbacks, s.begins_with('\''));

    // skip the opening quote
    _line_progressed(1);
    s = s.sub(1);

    bool needs_filter = false;

    size_t numlines = 1; // we already have one line
    size_t pos = npos; // find the pos of the matching quote
    while( ! _finished_file())
    {
        const csubstr line = m_state->line_contents.rem;
        bool line_is_blank = true;
        _c4dbgpf("scanning single quoted scalar @ line[{}]: ~~~{}~~~", m_state->pos.line, line);
        for(size_t i = 0; i < line.len; ++i)
        {
            const char curr = line.str[i];
            if(curr == '\'') // single quotes are escaped with two single quotes
            {
                const char next = i+1 < line.len ? line.str[i+1] : '~';
                if(next != '\'') // so just look for the first quote
                {                // without another after it
                    pos = i;
                    break;
                }
                else
                {
                    needs_filter = true; // needs filter to remove escaped quotes
                    ++i; // skip the escaped quote
                }
            }
            else if(curr != ' ')
            {
                line_is_blank = false;
            }
        }

        // leading whitespace also needs filtering
        needs_filter = needs_filter
            || (numlines > 1)
            || line_is_blank
            || (_at_line_begin() && line.begins_with(' '));

        if(pos == npos)
        {
            _line_progressed(line.len);
            ++numlines;
        }
        else
        {
            _RYML_CB_ASSERT(m_stack.m_callbacks, pos >= 0 && pos < m_buf.len);
            _RYML_CB_ASSERT(m_stack.m_callbacks, m_buf[m_state->pos.offset + pos] == '\'');
            _line_progressed(pos + 1); // progress beyond the quote
            pos = m_state->pos.offset - b - 1; // but we stop before it
            break;
        }

        _line_ended();
        _scan_line();
    }

    if(pos == npos)
    {
        _c4err("reached end of file while looking for closing quote");
    }
    else
    {
        _RYML_CB_ASSERT(m_stack.m_callbacks, pos > 0);
        _RYML_CB_ASSERT(m_stack.m_callbacks, s.end() >= m_buf.begin() && s.end() <= m_buf.end());
        _RYML_CB_ASSERT(m_stack.m_callbacks, s.end() == m_buf.end() || *s.end() == '\'');
        s = s.sub(0, pos-1);
    }

    if(needs_filter)
    {
        csubstr ret = _filter_squot_scalar(s);
        _RYML_CB_ASSERT(m_stack.m_callbacks, ret.len <= s.len || s.empty() || s.trim(' ').empty());
        _c4dbgpf("final scalar: \"{}\"", ret);
        return ret;
    }

    _c4dbgpf("final scalar: \"{}\"", s);

    return s;
}

//-----------------------------------------------------------------------------
csubstr Parser::_scan_dquot_scalar()
{
    // quoted scalars can spread over multiple lines!
    // nice explanation here: http://yaml-multiline.info/

    // a span to the end of the file
    size_t b = m_state->pos.offset;
    substr s = m_buf.sub(b);
    if(s.begins_with(' '))
    {
        s = s.triml(' ');
        _RYML_CB_ASSERT(m_stack.m_callbacks, m_buf.sub(b).is_super(s));
        _RYML_CB_ASSERT(m_stack.m_callbacks, s.begin() >= m_buf.sub(b).begin());
        _line_progressed((size_t)(s.begin() - m_buf.sub(b).begin()));
    }
    b = m_state->pos.offset; // take this into account
    _RYML_CB_ASSERT(m_stack.m_callbacks, s.begins_with('"'));

    // skip the opening quote
    _line_progressed(1);
    s = s.sub(1);

    bool needs_filter = false;

    size_t numlines = 1; // we already have one line
    size_t pos = npos; // find the pos of the matching quote
    while( ! _finished_file())
    {
        const csubstr line = m_state->line_contents.rem;
        bool line_is_blank = true;
        _c4dbgpf("scanning double quoted scalar @ line[{}]:  line='{}'", m_state->pos.line, line);
        for(size_t i = 0; i < line.len; ++i)
        {
            const char curr = line.str[i];
            if(curr != ' ')
                line_is_blank = false;
            // every \ is an escape
            if(curr == '\\')
            {
                const char next = i+1 < line.len ? line.str[i+1] : '~';
                needs_filter = true;
                if(next == '"' || next == '\\')
                    ++i;
            }
            else if(curr == '"')
            {
                pos = i;
                break;
            }
        }

        // leading whitespace also needs filtering
        needs_filter = needs_filter
            || (numlines > 1)
            || line_is_blank
            || (_at_line_begin() && line.begins_with(' '));

        if(pos == npos)
        {
            _line_progressed(line.len);
            ++numlines;
        }
        else
        {
            _RYML_CB_ASSERT(m_stack.m_callbacks, pos >= 0 && pos < m_buf.len);
            _RYML_CB_ASSERT(m_stack.m_callbacks, m_buf[m_state->pos.offset + pos] == '"');
            _line_progressed(pos + 1); // progress beyond the quote
            pos = m_state->pos.offset - b - 1; // but we stop before it
            break;
        }

        _line_ended();
        _scan_line();
    }

    if(pos == npos)
    {
        _c4err("reached end of file looking for closing quote");
    }
    else
    {
        _RYML_CB_ASSERT(m_stack.m_callbacks, pos > 0);
        _RYML_CB_ASSERT(m_stack.m_callbacks, s.end() == m_buf.end() || *s.end() == '"');
        _RYML_CB_ASSERT(m_stack.m_callbacks, s.end() >= m_buf.begin() && s.end() <= m_buf.end());
        s = s.sub(0, pos-1);
    }

    if(needs_filter)
    {
        csubstr ret = _filter_dquot_scalar(s);
        _c4dbgpf("final scalar: [{}]\"{}\"", ret.len, ret);
        _RYML_CB_ASSERT(m_stack.m_callbacks, ret.len <= s.len || s.empty() || s.trim(' ').empty());
        return ret;
    }

    _c4dbgpf("final scalar: \"{}\"", s);

    return s;
}

//-----------------------------------------------------------------------------
csubstr Parser::_scan_block()
{
    // nice explanation here: http://yaml-multiline.info/
    csubstr s = m_state->line_contents.rem;
    csubstr trimmed = s.triml(' ');
    if(trimmed.str > s.str)
    {
        _c4dbgp("skipping whitespace");
        _RYML_CB_ASSERT(m_stack.m_callbacks, trimmed.str >= s.str);
        _line_progressed(static_cast<size_t>(trimmed.str - s.str));
        s = trimmed;
    }
    _RYML_CB_ASSERT(m_stack.m_callbacks, s.begins_with('|') || s.begins_with('>'));

    _c4dbgpf("scanning block: specs=\"{}\"", s);

    // parse the spec
    BlockStyle_e newline = s.begins_with('>') ? BLOCK_FOLD : BLOCK_LITERAL;
    BlockChomp_e chomp = CHOMP_CLIP; // default to clip unless + or - are used
    size_t indentation = npos; // have to find out if no spec is given
    csubstr digits;
    if(s.len > 1)
    {
        _RYML_CB_ASSERT(m_stack.m_callbacks, s.begins_with_any("|>"));
        csubstr t = s.sub(1);
        _c4dbgpf("scanning block: spec is multichar: '{}'", t);
        _RYML_CB_ASSERT(m_stack.m_callbacks, t.len >= 1);
        size_t pos = t.first_of("-+");
        _c4dbgpf("scanning block: spec chomp char at {}", pos);
        if(pos != npos)
        {
            if(t[pos] == '-')
                chomp = CHOMP_STRIP;
            else if(t[pos] == '+')
                chomp = CHOMP_KEEP;
            if(pos == 0)
                t = t.sub(1);
            else
                t = t.first(pos);
        }
        // from here to the end, only digits are considered
        digits = t.left_of(t.first_not_of("0123456789"));
        if( ! digits.empty())
        {
            if( ! c4::atou(digits, &indentation))
                _c4err("parse error: could not read decimal");
            _c4dbgpf("scanning block: indentation specified: {}. add {} from curr state -> {}", indentation, m_state->indref, indentation+m_state->indref);
            indentation += m_state->indref;
        }
    }

    // finish the current line
    _line_progressed(s.len);
    _line_ended();
    _scan_line();

    _c4dbgpf("scanning block: style={}  chomp={}  indentation={}", newline==BLOCK_FOLD ? "fold" : "literal", chomp==CHOMP_CLIP ? "clip" : (chomp==CHOMP_STRIP ? "strip" : "keep"), indentation);

    // start with a zero-length block, already pointing at the right place
    substr raw_block(m_buf.data() + m_state->pos.offset, size_t(0));// m_state->line_contents.full.sub(0, 0);
    _RYML_CB_ASSERT(m_stack.m_callbacks, raw_block.begin() == m_state->line_contents.full.begin());

    // read every full line into a raw block,
    // from which newlines are to be stripped as needed.
    //
    // If no explicit indentation was given, pick it from the first
    // non-empty line. See
    // https://yaml.org/spec/1.2.2/#8111-block-indentation-indicator
    size_t num_lines = 0, first = m_state->pos.line, provisional_indentation = npos;
    LineContents lc;
    while(( ! _finished_file()))
    {
        // peek next line, but do not advance immediately
        lc.reset_with_next_line(m_buf, m_state->pos.offset);
        _c4dbgpf("scanning block: peeking at '{}'", lc.stripped);
        // evaluate termination conditions
        if(indentation != npos)
        {
            // stop when the line is deindented and not empty
            if(lc.indentation < indentation && ( ! lc.rem.trim(" \t\r\n").empty()))
            {
                _c4dbgpf("scanning block: indentation decreased ref={} thisline={}", indentation, lc.indentation);
                break;
            }
            else if(indentation == 0)
            {
                if((lc.rem == "..." || lc.rem.begins_with("... "))
                    ||
                   (lc.rem == "---" || lc.rem.begins_with("--- ")))
                {
                    _c4dbgp("scanning block: stop. indentation=0 and stream ended");
                    break;
                }
            }
        }
        else
        {
            _c4dbgpf("scanning block: indentation ref not set. firstnonws={}", lc.stripped.first_not_of(' '));
            if(lc.stripped.first_not_of(' ') != npos) // non-empty line
            {
                _c4dbgpf("scanning block: line not empty. indref={} indprov={} indentation={}", m_state->indref, provisional_indentation, lc.indentation);
                if(provisional_indentation == npos)
                {
                    if(lc.indentation < m_state->indref)
                    {
                        _c4dbgpf("scanning block: block terminated indentation={} < indref={}", lc.indentation, m_state->indref);
                        if(raw_block.len == 0)
                        {
                            _c4dbgp("scanning block: was empty, undo next line");
                            _line_ended_undo();
                        }
                        break;
                    }
                    else if(lc.indentation == m_state->indref)
                    {
                        if(has_any(RSEQ|RMAP))
                        {
                            _c4dbgpf("scanning block: block terminated. reading container and indentation={}==indref={}", lc.indentation, m_state->indref);
                            break;
                        }
                    }
                    _c4dbgpf("scanning block: set indentation ref from this line: ref={}", lc.indentation);
                    indentation = lc.indentation;
                }
                else
                {
                    if(lc.indentation >= provisional_indentation)
                    {
                        _c4dbgpf("scanning block: set indentation ref from provisional indentation: provisional_ref={}, thisline={}", provisional_indentation, lc.indentation);
                        //indentation = provisional_indentation ? provisional_indentation : lc.indentation;
                        indentation = lc.indentation;
                    }
                    else
                    {
                        break;
                        //_c4err("parse error: first non-empty block line should have at least the original indentation");
                    }
                }
            }
            else // empty line
            {
                _c4dbgpf("scanning block: line empty or {} spaces. line_indentation={} prov_indentation={}", lc.stripped.len, lc.indentation, provisional_indentation);
                if(provisional_indentation != npos)
                {
                    if(lc.stripped.len >= provisional_indentation)
                    {
                        _c4dbgpf("scanning block: increase provisional_ref {} -> {}", provisional_indentation, lc.stripped.len);
                        provisional_indentation = lc.stripped.len;
                    }
                    #ifdef RYML_NO_COVERAGE__TO_BE_DELETED
                    else if(lc.indentation >= provisional_indentation && lc.indentation != npos)
                    {
                        _c4dbgpf("scanning block: increase provisional_ref {} -> {}", provisional_indentation, lc.indentation);
                        provisional_indentation = lc.indentation;
                    }
                    #endif
                }
                else
                {
                    provisional_indentation = lc.indentation ? lc.indentation : has_any(RSEQ|RVAL);
                    _c4dbgpf("scanning block: initialize provisional_ref={}", provisional_indentation);
                    if(provisional_indentation == npos)
                    {
                        provisional_indentation = lc.stripped.len ? lc.stripped.len : has_any(RSEQ|RVAL);
                        _c4dbgpf("scanning block: initialize provisional_ref={}", provisional_indentation);
                    }
                }
            }
        }
        // advance now that we know the folded scalar continues
        m_state->line_contents = lc;
        _c4dbgpf("scanning block: append '{}'", m_state->line_contents.rem);
        raw_block.len += m_state->line_contents.full.len;
        _line_progressed(m_state->line_contents.rem.len);
        _line_ended();
        ++num_lines;
    }
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_state->pos.line == (first + num_lines) || (raw_block.len == 0));
    C4_UNUSED(num_lines);
    C4_UNUSED(first);

    if(indentation == npos)
    {
        _c4dbgpf("scanning block: set indentation from provisional: {}", provisional_indentation);
        indentation = provisional_indentation;
    }

    if(num_lines)
        _line_ended_undo();

    _c4dbgpf("scanning block: raw=~~~{}~~~", raw_block);

    // ok! now we strip the newlines and spaces according to the specs
    s = _filter_block_scalar(raw_block, newline, chomp, indentation);

    _c4dbgpf("scanning block: final=~~~{}~~~", s);

    return s;
}


//-----------------------------------------------------------------------------

template<bool backslash_is_escape, bool keep_trailing_whitespace>
bool Parser::_filter_nl(substr r, size_t *C4_RESTRICT i, size_t *C4_RESTRICT pos, size_t indentation)
{
    // a debugging scaffold:
    #if 0
    #define _c4dbgfnl(fmt, ...) _c4dbgpf("filter_nl[{}]: " fmt, *i, __VA_ARGS__)
    #else
    #define _c4dbgfnl(...)
    #endif

    const char curr = r[*i];
    bool replaced = false;

    _RYML_CB_ASSERT(m_stack.m_callbacks, indentation != npos);
    _RYML_CB_ASSERT(m_stack.m_callbacks, curr == '\n');

    _c4dbgfnl("found newline. sofar=[{}]~~~{}~~~", *pos, m_filter_arena.first(*pos));
    size_t ii = *i;
    size_t numnl_following = count_following_newlines(r, &ii, indentation);
    if(numnl_following)
    {
        _c4dbgfnl("{} consecutive (empty) lines {} in the middle. totalws={}", 1+numnl_following, ii < r.len ? "in the middle" : "at the end", ii - *i);
        for(size_t j = 0; j < numnl_following; ++j)
            m_filter_arena.str[(*pos)++] = '\n';
    }
    else
    {
        if(r.first_not_of(" \t", *i+1) != npos)
        {
            m_filter_arena.str[(*pos)++] = ' ';
            _c4dbgfnl("single newline. convert to space. ii={}/{}. sofar=[{}]~~~{}~~~", ii, r.len, *pos, m_filter_arena.first(*pos));
            replaced = true;
        }
        else
        {
            if C4_IF_CONSTEXPR (keep_trailing_whitespace)
            {
                m_filter_arena.str[(*pos)++] = ' ';
                _c4dbgfnl("single newline. convert to space. ii={}/{}. sofar=[{}]~~~{}~~~", ii, r.len, *pos, m_filter_arena.first(*pos));
                replaced = true;
            }
            else
            {
                _c4dbgfnl("last newline, everything else is whitespace. ii={}/{}", ii, r.len);
                *i = r.len;
            }
        }
        if C4_IF_CONSTEXPR (backslash_is_escape)
        {
            if(ii < r.len && r.str[ii] == '\\')
            {
                const char next = ii+1 < r.len ? r.str[ii+1] : '\0';
                if(next == ' ' || next == '\t')
                {
                    _c4dbgfnl("extend skip to backslash{}", "");
                    ++ii;
                }
            }
        }
    }
    *i = ii - 1; // correct for the loop increment

    #undef _c4dbgfnl

    return replaced;
}


//-----------------------------------------------------------------------------

template<bool keep_trailing_whitespace>
void Parser::_filter_ws(substr r, size_t *C4_RESTRICT i, size_t *C4_RESTRICT pos)
{
    // a debugging scaffold:
    #if 0
    #define _c4dbgfws(fmt, ...) _c4dbgpf("filt_nl[{}]: " fmt, *i, __VA_ARGS__)
    #else
    #define _c4dbgfws(...)
    #endif

    const char curr = r[*i];
    _c4dbgfws("found whitespace '{}'", _c4prc(curr));
    _RYML_CB_ASSERT(m_stack.m_callbacks, curr == ' ' || curr == '\t');

    size_t first = *i > 0 ? r.first_not_of(" \t", *i) : r.first_not_of(' ', *i);
    if(first != npos)
    {
        if(r[first] == '\n' || r[first] == '\r') // skip trailing whitespace
        {
            _c4dbgfws("whitespace is trailing on line. firstnonws='{}'@{}", _c4prc(r[first]), first);
            *i = first - 1; // correct for the loop increment
        }
        else // a legit whitespace
        {
            m_filter_arena.str[(*pos)++] = curr;
            _c4dbgfws("legit whitespace. sofar=[{}]~~~{}~~~", *pos, m_filter_arena.first(*pos));
        }
    }
    else
    {
        _c4dbgfws("... everything else is trailing whitespace{}", "");
        if C4_IF_CONSTEXPR (keep_trailing_whitespace)
            for(size_t j = *i; j < r.len; ++j)
                m_filter_arena.str[(*pos)++] = r[j];
        *i = r.len;
    }

    #undef _c4dbgfws
}


//-----------------------------------------------------------------------------
csubstr Parser::_filter_plain_scalar(substr s, size_t indentation)
{
    // a debugging scaffold:
    #if 0
    #define _c4dbgfps(...) _c4dbgpf("filt_plain_scalar" __VA_ARGS__)
    #else
    #define _c4dbgfps(...)
    #endif

    _c4dbgfps("before=~~~{}~~~", s);

    substr r = s.triml(" \t");
    _grow_filter_arena(r.len);
    size_t pos = 0; // the filtered size
    bool filtered_chars = false;
    for(size_t i = 0; i < r.len; ++i)
    {
        const char curr = r.str[i];
        _c4dbgfps("[{}]: '{}'", i, _c4prc(curr));
        if(curr == ' ' || curr == '\t')
        {
            _filter_ws</*keep_trailing_ws*/false>(r, &i, &pos);
        }
        else if(curr == '\n')
        {
            filtered_chars = _filter_nl</*backslash_is_escape*/false, /*keep_trailing_ws*/false>(r, &i, &pos, indentation);
        }
        else if(curr == '\r')  // skip \r --- https://stackoverflow.com/questions/1885900
        {
            ;
        }
        else
        {
            m_filter_arena.str[pos++] = r[i];
        }
    }

    _RYML_CB_ASSERT(m_stack.m_callbacks, pos <= m_filter_arena.len);
    if(pos < r.len || filtered_chars)
    {
        r = _finish_filter_arena(r, pos);
    }

    _RYML_CB_ASSERT(m_stack.m_callbacks, s.len >= r.len);
    _c4dbgfps("#filteredchars={} after=~~~{}~~~", s.len - r.len, r);

    #undef _c4dbgfps
    return r;
}


//-----------------------------------------------------------------------------
csubstr Parser::_filter_squot_scalar(substr s)
{
    // a debugging scaffold:
    #if 0
    #define _c4dbgfsq(...) _c4dbgpf("filt_squo_scalar")
    #else
    #define _c4dbgfsq(...)
    #endif

    // from the YAML spec for double-quoted scalars:
    // https://yaml.org/spec/1.2-old/spec.html#style/flow/single-quoted

    _c4dbgfsq(": before=~~~{}~~~", s);

    _grow_filter_arena(s.len);
    substr r = s;
    size_t pos = 0; // the filtered size
    bool filtered_chars = false;
    for(size_t i = 0; i < r.len; ++i)
    {
        const char curr = r[i];
        _c4dbgfsq("[{}]: '{}'", i, _c4prc(curr));
        if(curr == ' ' || curr == '\t')
        {
            _filter_ws</*keep_trailing_ws*/true>(r, &i, &pos);
        }
        else if(curr == '\n')
        {
            filtered_chars = _filter_nl</*backslash_is_escape*/false, /*keep_trailing_ws*/true>(r, &i, &pos, /*indentation*/0);
        }
        else if(curr == '\r')  // skip \r --- https://stackoverflow.com/questions/1885900
        {
            ;
        }
        else if(curr == '\'')
        {
            char next = i+1 < r.len ? r[i+1] : '\0';
            if(next == '\'')
            {
                _c4dbgfsq("[{}]: two consecutive quotes", i);
                filtered_chars = true;
                m_filter_arena.str[pos++] = '\'';
                ++i;
            }
        }
        else
        {
            m_filter_arena.str[pos++] = curr;
        }
    }

    _RYML_CB_ASSERT(m_stack.m_callbacks, pos <= m_filter_arena.len);
    if(pos < r.len || filtered_chars)
    {
        r = _finish_filter_arena(r, pos);
    }

    _RYML_CB_ASSERT(m_stack.m_callbacks, s.len >= r.len);
    _c4dbgpf(": #filteredchars={} after=~~~{}~~~", s.len - r.len, r);

    #undef _c4dbgfsq
    return r;
}


//-----------------------------------------------------------------------------
csubstr Parser::_filter_dquot_scalar(substr s)
{
    // a debugging scaffold:
    #if 0
    #define _c4dbgfdq(...) _c4dbgpf("filt_dquo_scalar" __VA_ARGS__)
    #else
    #define _c4dbgfdq(...)
    #endif

    _c4dbgfdq(": before=~~~{}~~~", s);

    // from the YAML spec for double-quoted scalars:
    // https://yaml.org/spec/1.2-old/spec.html#style/flow/double-quoted
    //
    // All leading and trailing white space characters are excluded
    // from the content. Each continuation line must therefore contain
    // at least one non-space character. Empty lines, if any, are
    // consumed as part of the line folding.

    _grow_filter_arena(s.len + 2u * s.count('\\'));
    substr r = s;
    size_t pos = 0; // the filtered size
    bool filtered_chars = false;
    for(size_t i = 0; i < r.len; ++i)
    {
        const char curr = r[i];
        _c4dbgfdq("[{}]: '{}'", i, _c4prc(curr));
        if(curr == ' ' || curr == '\t')
        {
            _filter_ws</*keep_trailing_ws*/true>(r, &i, &pos);
        }
        else if(curr == '\n')
        {
            filtered_chars = _filter_nl</*backslash_is_escape*/true, /*keep_trailing_ws*/true>(r, &i, &pos, /*indentation*/0);
        }
        else if(curr == '\r')  // skip \r --- https://stackoverflow.com/questions/1885900
        {
            ;
        }
        else if(curr == '\\')
        {
            char next = i+1 < r.len ? r[i+1] : '\0';
            _c4dbgfdq("[{}]: backslash, next='{}'", i, _c4prc(next));
            filtered_chars = true;
            if(next == '\r')
            {
                if(i+2 < r.len && r[i+2] == '\n')
                {
                    ++i; // newline escaped with \ -- skip both (add only one as i is loop-incremented)
                    next = '\n';
                    _c4dbgfdq("[{}]: was \\r\\n, now next='\\n'", i);
                }
            }
            // remember the loop will also increment i
            if(next == '\n')
            {
                size_t ii = i + 2;
                for( ; ii < r.len; ++ii)
                {
                    if(r.str[ii] == ' ' || r.str[ii] == '\t')  // skip leading whitespace
                        ;
                    else
                        break;
                }
                i += ii - i - 1;
            }
            else if(next == '"' || next == '/'  || next == ' ' || next == '\t') // escapes for json compatibility
            {
                m_filter_arena.str[pos++] = next;
                ++i;
            }
            else if(next == '\r')
            {
                //++i;
            }
            else if(next == 'n')
            {
                m_filter_arena.str[pos++] = '\n';
                ++i;
            }
            else if(next == 'r')
            {
                m_filter_arena.str[pos++] = '\r';
                ++i; // skip
            }
            else if(next == 't')
            {
                m_filter_arena.str[pos++] = '\t';
                ++i;
            }
            else if(next == '\\')
            {
                m_filter_arena.str[pos++] = '\\';
                ++i;
            }
            else if(next == 'x') // UTF8
            {
                if(i + 1u + 2u >= r.len)
                    _c4err("\\x requires 2 hex digits");
                uint8_t byteval = {};
                if(!read_hex(r.sub(i + 2u, 2u), &byteval))
                    _c4err("failed to read \\x codepoint");
                m_filter_arena.str[pos++] = *(char*)&byteval;
                i += 1u + 2u;
            }
            else if(next == 'u') // UTF16
            {
                if(i + 1u + 4u >= r.len)
                    _c4err("\\u requires 4 hex digits");
                char readbuf[8];
                csubstr codepoint = r.sub(i + 2u, 4u);
                uint32_t codepoint_val = {};
                if(!read_hex(codepoint, &codepoint_val))
                    _c4err("failed to parse \\u codepoint");
                size_t numbytes = decode_code_point((uint8_t*)readbuf, sizeof(readbuf), codepoint_val);
                C4_ASSERT(numbytes <= 4);
                memcpy(m_filter_arena.str + pos, readbuf, numbytes);
                pos += numbytes;
                i += 1u + 4u;
            }
            else if(next == 'U') // UTF32
            {
                if(i + 1u + 8u >= r.len)
                    _c4err("\\U requires 8 hex digits");
                char readbuf[8];
                csubstr codepoint = r.sub(i + 2u, 8u);
                uint32_t codepoint_val = {};
                if(!read_hex(codepoint, &codepoint_val))
                    _c4err("failed to parse \\U codepoint");
                size_t numbytes = decode_code_point((uint8_t*)readbuf, sizeof(readbuf), codepoint_val);
                C4_ASSERT(numbytes <= 4);
                memcpy(m_filter_arena.str + pos, readbuf, numbytes);
                pos += numbytes;
                i += 1u + 8u;
            }
            // https://yaml.org/spec/1.2.2/#rule-c-ns-esc-char
            else if(next == '0')
            {
                m_filter_arena.str[pos++] = '\0';
                ++i;
            }
            else if(next == 'b') // backspace
            {
                m_filter_arena.str[pos++] = '\b';
                ++i;
            }
            else if(next == 'f') // form feed
            {
                m_filter_arena.str[pos++] = '\f';
                ++i;
            }
            else if(next == 'a') // bell character
            {
                m_filter_arena.str[pos++] = '\a';
                ++i;
            }
            else if(next == 'v') // vertical tab
            {
                m_filter_arena.str[pos++] = '\v';
                ++i;
            }
            else if(next == 'e') // escape character
            {
                m_filter_arena.str[pos++] = '\x1b';
                ++i;
            }
            else if(next == '_') // unicode non breaking space \u00a0
            {
                // https://www.compart.com/en/unicode/U+00a0
                m_filter_arena.str[pos++] = _RYML_CHCONST(-0x3e, 0xc2);
                m_filter_arena.str[pos++] = _RYML_CHCONST(-0x60, 0xa0);
                ++i;
            }
            else if(next == 'N') // unicode next line \u0085
            {
                // https://www.compart.com/en/unicode/U+0085
                m_filter_arena.str[pos++] = _RYML_CHCONST(-0x3e, 0xc2);
                m_filter_arena.str[pos++] = _RYML_CHCONST(-0x7b, 0x85);
                ++i;
            }
            else if(next == 'L') // unicode line separator \u2028
            {
                // https://www.utf8-chartable.de/unicode-utf8-table.pl?start=8192&number=1024&names=-&utf8=0x&unicodeinhtml=hex
                m_filter_arena.str[pos++] = _RYML_CHCONST(-0x1e, 0xe2);
                m_filter_arena.str[pos++] = _RYML_CHCONST(-0x80, 0x80);
                m_filter_arena.str[pos++] = _RYML_CHCONST(-0x58, 0xa8);
                ++i;
            }
            else if(next == 'P') // unicode paragraph separator \u2029
            {
                // https://www.utf8-chartable.de/unicode-utf8-table.pl?start=8192&number=1024&names=-&utf8=0x&unicodeinhtml=hex
                m_filter_arena.str[pos++] = _RYML_CHCONST(-0x1e, 0xe2);
                m_filter_arena.str[pos++] = _RYML_CHCONST(-0x80, 0x80);
                m_filter_arena.str[pos++] = _RYML_CHCONST(-0x57, 0xa9);
                ++i;
            }
            _c4dbgfdq("[{}]: backslash...sofar=[{}]~~~{}~~~", i, pos, m_filter_arena.first(pos));
        }
        else
        {
            m_filter_arena.str[pos++] = curr;
        }
    }

    _RYML_CB_ASSERT(m_stack.m_callbacks, pos <= m_filter_arena.len);
    if(pos < r.len || filtered_chars)
    {
        r = _finish_filter_arena(r, pos);
    }

    _RYML_CB_ASSERT(m_stack.m_callbacks, s.len >= r.len);
    _c4dbgpf(": #filteredchars={} after=~~~{}~~~", s.len - r.len, r);

    #undef _c4dbgfdq

    return r;
}


//-----------------------------------------------------------------------------
bool Parser::_apply_chomp(substr buf, size_t *C4_RESTRICT pos, BlockChomp_e chomp)
{
    substr trimmed = buf.first(*pos).trimr('\n');
    bool added_newline = false;
    switch(chomp)
    {
    case CHOMP_KEEP:
        if(trimmed.len == *pos)
        {
            _c4dbgpf("chomp=KEEP: add missing newline @{}", *pos);
            //m_filter_arena.str[(*pos)++] = '\n';
            added_newline = true;
        }
        break;
    case CHOMP_CLIP:
        if(trimmed.len == *pos)
        {
            _c4dbgpf("chomp=CLIP: add missing newline @{}", *pos);
            m_filter_arena.str[(*pos)++] = '\n';
            added_newline = true;
        }
        else
        {
            _c4dbgpf("chomp=CLIP: include single trailing newline @{}", trimmed.len+1);
            *pos = trimmed.len + 1;
        }
        break;
    case CHOMP_STRIP:
        _c4dbgpf("chomp=STRIP: strip {}-{}-{} newlines", *pos, trimmed.len, *pos-trimmed.len);
        *pos = trimmed.len;
        break;
    default:
        _c4err("unknown chomp style");
    }
    return added_newline;
}


//-----------------------------------------------------------------------------
csubstr Parser::_filter_block_scalar(substr s, BlockStyle_e style, BlockChomp_e chomp, size_t indentation)
{
    // a debugging scaffold:
    #if 0
    #define _c4dbgfbl(fmt, ...) _c4dbgpf("filt_block" fmt, __VA_ARGS__)
    #else
    #define _c4dbgfbl(...)
    #endif

    _c4dbgfbl(": indentation={} before=[{}]~~~{}~~~", indentation, s.len, s);

    if(chomp != CHOMP_KEEP && s.trim(" \n\r").len == 0u)
    {
        _c4dbgp("filt_block: empty scalar");
        return s.first(0);
    }

    substr r = s;

    switch(style)
    {
    case BLOCK_LITERAL:
        {
            _c4dbgp("filt_block: style=literal");
            // trim leading whitespace up to indentation
            {
                size_t numws = r.first_not_of(' ');
                if(numws != npos)
                {
                    if(numws > indentation)
                        r = r.sub(indentation);
                    else
                        r = r.sub(numws);
                    _c4dbgfbl(": after triml=[{}]~~~{}~~~", r.len, r);
                }
                else
                {
                    if(chomp != CHOMP_KEEP || r.len == 0)
                    {
                        _c4dbgfbl(": all spaces {}, return empty", r.len);
                        return r.first(0);
                    }
                    else
                    {
                        r[0] = '\n';
                        return r.first(1);
                    }
                }
            }
            _grow_filter_arena(s.len + 2u);  // use s.len! because we may need to add a newline at the end, so the leading indentation will allow space for that newline
            size_t pos = 0; // the filtered size
            for(size_t i = 0; i < r.len; ++i)
            {
                const char curr = r.str[i];
                _c4dbgfbl("[{}]='{}'  pos={}", i, _c4prc(curr), pos);
                if(curr == '\r')
                    continue;
                m_filter_arena.str[pos++] = curr;
                if(curr == '\n')
                {
                    _c4dbgfbl("[{}]: found newline", i);
                    // skip indentation on the next line
                    csubstr rem = r.sub(i+1);
                    size_t first = rem.first_not_of(' ');
                    if(first != npos)
                    {
                        _RYML_CB_ASSERT(m_stack.m_callbacks, first < rem.len);
                        _RYML_CB_ASSERT(m_stack.m_callbacks, i+1+first < r.len);
                        _c4dbgfbl("[{}]: {} spaces follow before next nonws character @ [{}]='{}'", i, first, i+1+first, rem.str[first]);
                        if(first < indentation)
                        {
                            _c4dbgfbl("[{}]: skip {}<{} spaces from indentation", i, first, indentation);
                            i += first;
                        }
                        else
                        {
                            _c4dbgfbl("[{}]: skip {} spaces from indentation", i, indentation);
                            i += indentation;
                        }
                    }
                    else
                    {
                        _RYML_CB_ASSERT(m_stack.m_callbacks, i+1 <= r.len);
                        first = rem.len;
                        _c4dbgfbl("[{}]: {} spaces to the end", i, first);
                        if(first)
                        {
                            if(first < indentation)
                            {
                                _c4dbgfbl("[{}]: skip everything", i);
                                --pos;
                                break;
                            }
                            else
                            {
                                _c4dbgfbl("[{}]: skip {} spaces from indentation", i, indentation);
                                i += indentation;
                            }
                        }
                        else if(i+1 == r.len)
                        {
                            if(chomp == CHOMP_STRIP)
                                --pos;
                            break;
                        }
                    }
                }
            }
            _RYML_CB_ASSERT(m_stack.m_callbacks, s.len >= pos);
            _c4dbgfbl(": #filteredchars={} after=~~~{}~~~", s.len - r.len, r);
            bool changed = _apply_chomp(m_filter_arena, &pos, chomp);
            _RYML_CB_ASSERT(m_stack.m_callbacks, pos <= m_filter_arena.len);
            _RYML_CB_ASSERT(m_stack.m_callbacks, pos <= s.len);
            if(pos < r.len || changed)
            {
                r = _finish_filter_arena(s, pos); // write into s
            }
            break;
        }
    case BLOCK_FOLD:
        {
            _c4dbgp("filt_block: style=fold");
            _grow_filter_arena(r.len + 2);
            size_t pos = 0; // the filtered size
            bool filtered_chars = false;
            bool started = false;
            bool is_indented = false;
            size_t i = r.first_not_of(' ');
            _c4dbgfbl(": first non space at {}", i);
            if(i > indentation)
            {
                is_indented = true;
                i = indentation;
            }
            _c4dbgfbl(": start folding at {}, is_indented={}", i, (int)is_indented);
            auto on_change_indentation = [&](size_t numnl_following, size_t last_newl, size_t first_non_whitespace){
                _c4dbgfbl("[{}]: add 1+{} newlines", i, numnl_following);
                for(size_t j = 0; j < 1 + numnl_following; ++j)
                    m_filter_arena.str[pos++] = '\n';
                for(i = last_newl + 1 + indentation; i < first_non_whitespace; ++i)
                {
                    if(r.str[i] == '\r')
                        continue;
                    _c4dbgfbl("[{}]: add '{}'", i, _c4prc(r.str[i]));
                    m_filter_arena.str[pos++] = r.str[i];
                }
                --i;
            };
            for( ; i < r.len; ++i)
            {
                const char curr = r.str[i];
                _c4dbgfbl("[{}]='{}'", i, _c4prc(curr));
                if(curr == '\n')
                {
                    filtered_chars = true;
                    // skip indentation on the next line, and advance over the next non-indented blank lines as well
                    size_t first_non_whitespace;
                    size_t numnl_following = (size_t)-1;
                    while(r[i] == '\n')
                    {
                        ++numnl_following;
                        csubstr rem = r.sub(i+1);
                        size_t first = rem.first_not_of(' ');
                        _c4dbgfbl("[{}]: found newline. first={} rem.len={}", i, first, rem.len);
                        if(first != npos)
                        {
                            first_non_whitespace = first + i+1;
                            while(first_non_whitespace < r.len && r[first_non_whitespace] == '\r')
                                ++first_non_whitespace;
                            _RYML_CB_ASSERT(m_stack.m_callbacks, first < rem.len);
                            _RYML_CB_ASSERT(m_stack.m_callbacks, i+1+first < r.len);
                            _c4dbgfbl("[{}]: {} spaces follow before next nonws character @ [{}]='{}'", i, first, i+1+first, _c4prc(rem.str[first]));
                            if(first < indentation)
                            {
                                _c4dbgfbl("[{}]: skip {}<{} spaces from indentation", i, first, indentation);
                                i += first;
                            }
                            else
                            {
                                _c4dbgfbl("[{}]: skip {} spaces from indentation", i, indentation);
                                i += indentation;
                                if(first > indentation)
                                {
                                    _c4dbgfbl("[{}]: {} further indented than {}, stop newlining", i, first, indentation);
                                    goto finished_counting_newlines;
                                }
                            }
                            // prepare the next while loop iteration
                            // by setting i at the next newline after
                            // an empty line
                            if(r[first_non_whitespace] == '\n')
                                i = first_non_whitespace;
                            else
                                goto finished_counting_newlines;
                        }
                        else
                        {
                            _RYML_CB_ASSERT(m_stack.m_callbacks, i+1 <= r.len);
                            first = rem.len;
                            first_non_whitespace = first + i+1;
                            if(first)
                            {
                                _c4dbgfbl("[{}]: {} spaces to the end", i, first);
                                if(first < indentation)
                                {
                                    _c4dbgfbl("[{}]: skip everything", i);
                                    i += first;
                                }
                                else
                                {
                                    _c4dbgfbl("[{}]: skip {} spaces from indentation", i, indentation);
                                    i += indentation;
                                    if(first > indentation)
                                    {
                                        _c4dbgfbl("[{}]: {} spaces missing. not done yet", i, indentation - first);
                                        goto finished_counting_newlines;
                                    }
                                }
                            }
                            else // if(i+1 == r.len)
                            {
                                _c4dbgfbl("[{}]: it's the final newline", i);
                                _RYML_CB_ASSERT(m_stack.m_callbacks, i+1 == r.len);
                                _RYML_CB_ASSERT(m_stack.m_callbacks, rem.len == 0);
                            }
                            goto end_of_scalar;
                        }
                    }
                end_of_scalar:
                    // Write all the trailing newlines. Since we're
                    // at the end no folding is needed, so write every
                    // newline (add 1).
                    _c4dbgfbl("[{}]: add {} trailing newlines", i, 1+numnl_following);
                    for(size_t j = 0; j < 1 + numnl_following; ++j)
                        m_filter_arena.str[pos++] = '\n';
                    break;
                finished_counting_newlines:
                    _c4dbgfbl("[{}]: #newlines={} firstnonws={}", i, numnl_following, first_non_whitespace);
                    while(first_non_whitespace < r.len && r[first_non_whitespace] == '\t')
                        ++first_non_whitespace;
                    _c4dbgfbl("[{}]: #newlines={} firstnonws={}", i, numnl_following, first_non_whitespace);
                    _RYML_CB_ASSERT(m_stack.m_callbacks, first_non_whitespace <= r.len);
                    size_t last_newl = r.last_of('\n', first_non_whitespace);
                    size_t this_indentation = first_non_whitespace - last_newl - 1;
                    _c4dbgfbl("[{}]: #newlines={} firstnonws={} lastnewl={} this_indentation={} vs indentation={}", i, numnl_following, first_non_whitespace, last_newl, this_indentation, indentation);
                    _RYML_CB_ASSERT(m_stack.m_callbacks, first_non_whitespace >= last_newl + 1);
                    _RYML_CB_ASSERT(m_stack.m_callbacks, this_indentation >= indentation);
                    if(!started)
                    {
                        _c4dbgfbl("[{}]: #newlines={}. write all leading newlines", i, numnl_following);
                        for(size_t j = 0; j < 1 + numnl_following; ++j)
                            m_filter_arena.str[pos++] = '\n';
                        if(this_indentation > indentation)
                        {
                            is_indented = true;
                            _c4dbgfbl("[{}]: advance ->{}", i, last_newl + indentation);
                            i = last_newl + indentation;
                        }
                        else
                        {
                            i = first_non_whitespace - 1;
                            _c4dbgfbl("[{}]: advance ->{}", i, first_non_whitespace);
                        }
                    }
                    else if(this_indentation == indentation)
                    {
                        _c4dbgfbl("[{}]: same indentation", i);
                        if(!is_indented)
                        {
                            if(numnl_following == 0)
                            {
                                _c4dbgfbl("[{}]: fold!", i);
                                m_filter_arena.str[pos++] = ' ';
                            }
                            else
                            {
                                _c4dbgfbl("[{}]: add {} newlines", i, 1 + numnl_following);
                                for(size_t j = 0; j < numnl_following; ++j)
                                    m_filter_arena.str[pos++] = '\n';
                            }
                            i = first_non_whitespace - 1;
                            _c4dbgfbl("[{}]: advance {}->{}", i, i, first_non_whitespace);
                        }
                        else
                        {
                            _c4dbgfbl("[{}]: back to ref indentation", i);
                            is_indented = false;
                            on_change_indentation(numnl_following, last_newl, first_non_whitespace);
                            _c4dbgfbl("[{}]: advance {}->{}", i, i, first_non_whitespace);
                        }
                    }
                    else
                    {
                        _c4dbgfbl("[{}]: increased indentation.", i);
                        is_indented = true;
                        _RYML_CB_ASSERT(m_stack.m_callbacks, this_indentation > indentation);
                        on_change_indentation(numnl_following, last_newl, first_non_whitespace);
                        _c4dbgfbl("[{}]: advance {}->{}", i, i, first_non_whitespace);
                    }
                }
                else if(curr != '\r')
                {
                    if(curr != '\t')
                        started = true;
                    m_filter_arena.str[pos++] = curr;
                }
            }
            _RYML_CB_ASSERT(m_stack.m_callbacks, pos <= m_filter_arena.len);
            _c4dbgfbl(": #filteredchars={} after=[{}]~~~{}~~~", (int)s.len - (int)pos, pos, m_filter_arena.first(pos));
            bool changed = _apply_chomp(m_filter_arena, &pos, chomp);
            if(pos < r.len || filtered_chars || changed)
            {
                r = _finish_filter_arena(s, pos); // write into s
            }
        }
        break;
    default:
        _c4err("unknown block style");
    }

    _c4dbgfbl(": final=[{}]~~~{}~~~", r.len, r);

    #undef _c4dbgfbl

    return r;
}

//-----------------------------------------------------------------------------
size_t Parser::_count_nlines(csubstr src)
{
    return 1 + src.count('\n');
}

//-----------------------------------------------------------------------------
void Parser::_handle_directive(csubstr directive_)
{
    csubstr directive = directive_;
    if(directive.begins_with("%TAG"))
    {
        TagDirective td;
        _c4dbgpf("%TAG directive: {}", directive_);
        directive = directive.sub(4);
        if(!directive.begins_with(' '))
            _c4err("malformed tag directive: {}", directive_);
        directive = directive.triml(' ');
        size_t pos = directive.find(' ');
        if(pos == npos)
            _c4err("malformed tag directive: {}", directive_);
        td.handle = directive.first(pos);
        directive = directive.sub(td.handle.len).triml(' ');
        pos = directive.find(' ');
        if(pos != npos)
            directive = directive.first(pos);
        td.prefix = directive;
        td.next_node_id = m_tree->size();
        if(m_tree->size() > 0)
        {
            size_t prev = m_tree->size() - 1;
            if(m_tree->is_root(prev) && m_tree->type(prev) != NOTYPE && !m_tree->is_stream(prev))
                ++td.next_node_id;
        }
        _c4dbgpf("%TAG: handle={} prefix={} next_node={}", td.handle, td.prefix, td.next_node_id);
        m_tree->add_tag_directive(td);
    }
    else if(directive.begins_with("%YAML"))
    {
        _c4dbgpf("%YAML directive! ignoring...: {}", directive);
    }
}

//-----------------------------------------------------------------------------
void Parser::set_flags(flag_t f, State * s)
{
#ifdef RYML_DBG
    char buf1_[64], buf2_[64];
    csubstr buf1 = _prfl(buf1_, f);
    csubstr buf2 = _prfl(buf2_, s->flags);
    _c4dbgpf("state[{}]: setting flags to {}: before={}", s-m_stack.begin(), buf1, buf2);
#endif
    s->flags = f;
}

void Parser::add_flags(flag_t on, State * s)
{
#ifdef RYML_DBG
    char buf1_[64], buf2_[64], buf3_[64];
    csubstr buf1 = _prfl(buf1_, on);
    csubstr buf2 = _prfl(buf2_, s->flags);
    csubstr buf3 = _prfl(buf3_, s->flags|on);
    _c4dbgpf("state[{}]: adding flags {}: before={} after={}", s-m_stack.begin(), buf1, buf2, buf3);
#endif
    s->flags |= on;
}

void Parser::addrem_flags(flag_t on, flag_t off, State * s)
{
#ifdef RYML_DBG
    char buf1_[64], buf2_[64], buf3_[64], buf4_[64];
    csubstr buf1 = _prfl(buf1_, on);
    csubstr buf2 = _prfl(buf2_, off);
    csubstr buf3 = _prfl(buf3_, s->flags);
    csubstr buf4 = _prfl(buf4_, ((s->flags|on)&(~off)));
    _c4dbgpf("state[{}]: adding flags {} / removing flags {}: before={} after={}", s-m_stack.begin(), buf1, buf2, buf3, buf4);
#endif
    s->flags |= on;
    s->flags &= ~off;
}

void Parser::rem_flags(flag_t off, State * s)
{
#ifdef RYML_DBG
    char buf1_[64], buf2_[64], buf3_[64];
    csubstr buf1 = _prfl(buf1_, off);
    csubstr buf2 = _prfl(buf2_, s->flags);
    csubstr buf3 = _prfl(buf3_, s->flags&(~off));
    _c4dbgpf("state[{}]: removing flags {}: before={} after={}", s-m_stack.begin(), buf1, buf2, buf3);
#endif
    s->flags &= ~off;
}

//-----------------------------------------------------------------------------

csubstr Parser::_prfl(substr buf, flag_t flags)
{
    size_t pos = 0;
    bool gotone = false;

    #define _prflag(fl)                                     \
    if((flags & fl) == (fl))                                \
    {                                                       \
        if(gotone)                                          \
        {                                                   \
            if(pos + 1 < buf.len)                           \
                buf[pos] = '|';                             \
            ++pos;                                          \
        }                                                   \
        csubstr fltxt = #fl;                                \
        if(pos + fltxt.len <= buf.len)                      \
            memcpy(buf.str + pos, fltxt.str, fltxt.len);    \
        pos += fltxt.len;                                   \
        gotone = true;                                      \
    }

    _prflag(RTOP);
    _prflag(RUNK);
    _prflag(RMAP);
    _prflag(RSEQ);
    _prflag(FLOW);
    _prflag(QMRK);
    _prflag(RKEY);
    _prflag(RVAL);
    _prflag(RNXT);
    _prflag(SSCL);
    _prflag(QSCL);
    _prflag(RSET);
    _prflag(NDOC);
    _prflag(RSEQIMAP);

    #undef _prflag

    RYML_ASSERT(pos <= buf.len);

    return buf.first(pos);
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

void Parser::_grow_filter_arena(size_t num_characters_needed)
{
    _c4dbgpf("grow: arena={} numchars={}", m_filter_arena.len, num_characters_needed);
    if(num_characters_needed <= m_filter_arena.len)
        return;
    size_t sz = m_filter_arena.len << 1;
    _c4dbgpf("grow: sz={}", sz);
    sz = num_characters_needed > sz ? num_characters_needed : sz;
    _c4dbgpf("grow: sz={}", sz);
    sz = sz < 128u ? 128u : sz;
    _c4dbgpf("grow: sz={}", sz);
    _RYML_CB_ASSERT(m_stack.m_callbacks, sz >= num_characters_needed);
    _resize_filter_arena(sz);
}

void Parser::_resize_filter_arena(size_t num_characters)
{
    if(num_characters > m_filter_arena.len)
    {
        _c4dbgpf("resize: sz={}", num_characters);
        char *prev = m_filter_arena.str;
        if(m_filter_arena.str)
        {
            _RYML_CB_ASSERT(m_stack.m_callbacks, m_filter_arena.len > 0);
            _RYML_CB_FREE(m_stack.m_callbacks, m_filter_arena.str, char, m_filter_arena.len);
        }
        m_filter_arena.str = _RYML_CB_ALLOC_HINT(m_stack.m_callbacks, char, num_characters, prev);
        m_filter_arena.len = num_characters;
    }
}

substr Parser::_finish_filter_arena(substr dst, size_t pos)
{
    _RYML_CB_ASSERT(m_stack.m_callbacks, pos <= m_filter_arena.len);
    _RYML_CB_ASSERT(m_stack.m_callbacks, pos <= dst.len);
    memcpy(dst.str, m_filter_arena.str, pos);
    return dst.first(pos);
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

csubstr Parser::location_contents(Location const& loc) const
{
    _RYML_CB_ASSERT(m_stack.m_callbacks, loc.offset < m_buf.len);
    return m_buf.sub(loc.offset);
}

Location Parser::location(ConstNodeRef node) const
{
    _RYML_CB_ASSERT(m_stack.m_callbacks, node.valid());
    return location(*node.tree(), node.id());
}

Location Parser::location(Tree const& tree, size_t node) const
{
    // try hard to avoid getting the location from a null string.
    Location loc;
    if(_location_from_node(tree, node, &loc, 0))
        return loc;
    return val_location(m_buf.str);
}

bool Parser::_location_from_node(Tree const& tree, size_t node, Location *C4_RESTRICT loc, size_t level) const
{
    if(tree.has_key(node))
    {
        csubstr k = tree.key(node);
        if(C4_LIKELY(k.str != nullptr))
        {
            _RYML_CB_ASSERT(m_stack.m_callbacks, k.is_sub(m_buf));
            _RYML_CB_ASSERT(m_stack.m_callbacks, m_buf.is_super(k));
            *loc = val_location(k.str);
            return true;
        }
    }

    if(tree.has_val(node))
    {
        csubstr v = tree.val(node);
        if(C4_LIKELY(v.str != nullptr))
        {
            _RYML_CB_ASSERT(m_stack.m_callbacks, v.is_sub(m_buf));
            _RYML_CB_ASSERT(m_stack.m_callbacks, m_buf.is_super(v));
            *loc = val_location(v.str);
            return true;
        }
    }

    if(tree.is_container(node))
    {
        if(_location_from_cont(tree, node, loc))
            return true;
    }

    if(tree.type(node) != NOTYPE && level == 0)
    {
        // try the prev sibling
        {
            const size_t prev = tree.prev_sibling(node);
            if(prev != NONE)
            {
                if(_location_from_node(tree, prev, loc, level+1))
                    return true;
            }
        }
        // try the next sibling
        {
            const size_t next = tree.next_sibling(node);
            if(next != NONE)
            {
                if(_location_from_node(tree, next, loc, level+1))
                    return true;
            }
        }
        // try the parent
        {
            const size_t parent = tree.parent(node);
            if(parent != NONE)
            {
                if(_location_from_node(tree, parent, loc, level+1))
                    return true;
            }
        }
    }

    return false;
}

bool Parser::_location_from_cont(Tree const& tree, size_t node, Location *C4_RESTRICT loc) const
{
    _RYML_CB_ASSERT(m_stack.m_callbacks, tree.is_container(node));
    if(!tree.is_stream(node))
    {
        const char *node_start = tree._p(node)->m_val.scalar.str;  // this was stored in the container
        if(tree.has_children(node))
        {
            size_t child = tree.first_child(node);
            if(tree.has_key(child))
            {
                // when a map starts, the container was set after the key
                csubstr k = tree.key(child);
                if(k.str && node_start > k.str)
                    node_start = k.str;
            }
        }
        *loc = val_location(node_start);
        return true;
    }
    else // it's a stream
    {
        *loc = val_location(m_buf.str); // just return the front of the buffer
    }
    return true;
}


Location Parser::val_location(const char *val) const
{
    if(C4_UNLIKELY(val == nullptr))
        return {m_file, 0, 0, 0};

    _RYML_CB_CHECK(m_stack.m_callbacks, m_options.locations());
    // NOTE: if any of these checks fails, the parser needs to be
    // instantiated with locations enabled.
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_buf.str == m_newline_offsets_buf.str);
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_buf.len == m_newline_offsets_buf.len);
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_options.locations());
    _RYML_CB_ASSERT(m_stack.m_callbacks, !_locations_dirty());
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_newline_offsets != nullptr);
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_newline_offsets_size > 0);
    // NOTE: the pointer needs to belong to the buffer that was used to parse.
    csubstr src = m_buf;
    _RYML_CB_CHECK(m_stack.m_callbacks, val != nullptr || src.str == nullptr);
    _RYML_CB_CHECK(m_stack.m_callbacks, (val >= src.begin() && val <= src.end()) || (src.str == nullptr && val == nullptr));
    // ok. search the first stored newline after the given ptr
    using lineptr_type = size_t const* C4_RESTRICT;
    lineptr_type lineptr = nullptr;
    size_t offset = (size_t)(val - src.begin());
    if(m_newline_offsets_size < 30) // TODO magic number
    {
        // just do a linear search if the size is small.
        for(lineptr_type curr = m_newline_offsets, last = m_newline_offsets + m_newline_offsets_size; curr < last; ++curr)
        {
            if(*curr > offset)
            {
                lineptr = curr;
                break;
            }
        }
    }
    else
    {
        // do a bisection search if the size is not small.
        //
        // We could use std::lower_bound but this is simple enough and
        // spares the include of <algorithm>.
        size_t count = m_newline_offsets_size;
        size_t step;
        lineptr_type it;
        lineptr = m_newline_offsets;
        while(count)
        {
            step = count >> 1;
            it = lineptr + step;
            if(*it < offset)
            {
                lineptr = ++it;
                count -= step + 1;
            }
            else
            {
                count = step;
            }
        }
    }
    _RYML_CB_ASSERT(m_stack.m_callbacks, lineptr >= m_newline_offsets);
    _RYML_CB_ASSERT(m_stack.m_callbacks, lineptr <= m_newline_offsets + m_newline_offsets_size);
    _RYML_CB_ASSERT(m_stack.m_callbacks, *lineptr > offset);
    Location loc;
    loc.name = m_file;
    loc.offset = offset;
    loc.line = (size_t)(lineptr - m_newline_offsets);
    if(lineptr > m_newline_offsets)
        loc.col = (offset - *(lineptr-1) - 1u);
    else
        loc.col = offset;
    return loc;
}

void Parser::_prepare_locations()
{
    m_newline_offsets_buf = m_buf;
    size_t numnewlines = 1u + m_buf.count('\n');
    _resize_locations(numnewlines);
    m_newline_offsets_size = 0;
    for(size_t i = 0; i < m_buf.len; i++)
        if(m_buf[i] == '\n')
            m_newline_offsets[m_newline_offsets_size++] = i;
    m_newline_offsets[m_newline_offsets_size++] = m_buf.len;
    _RYML_CB_ASSERT(m_stack.m_callbacks, m_newline_offsets_size == numnewlines);
}

void Parser::_resize_locations(size_t numnewlines)
{
    if(numnewlines > m_newline_offsets_capacity)
    {
        if(m_newline_offsets)
            _RYML_CB_FREE(m_stack.m_callbacks, m_newline_offsets, size_t, m_newline_offsets_capacity);
        m_newline_offsets = _RYML_CB_ALLOC_HINT(m_stack.m_callbacks, size_t, numnewlines, m_newline_offsets);
        m_newline_offsets_capacity = numnewlines;
    }
}

bool Parser::_locations_dirty() const
{
    return !m_newline_offsets_size;
}

} // namespace yml
} // namespace c4


#if defined(_MSC_VER)
#   pragma warning(pop)
#elif defined(__clang__)
#   pragma clang diagnostic pop
#elif defined(__GNUC__)
#   pragma GCC diagnostic pop
#endif

#endif /* RYML_SINGLE_HDR_DEFINE_NOW */


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/parse.cpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/node.cpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/node.cpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifdef RYML_SINGLE_HDR_DEFINE_NOW
// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/node.hpp
//#include "c4/yml/node.hpp"
#if !defined(C4_YML_NODE_HPP_) && !defined(_C4_YML_NODE_HPP_)
#error "amalgamate: file c4/yml/node.hpp must have been included at this point"
#endif /* C4_YML_NODE_HPP_ */


namespace c4 {
namespace yml {




//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

size_t NodeRef::set_key_serialized(c4::fmt::const_base64_wrapper w)
{
    _apply_seed();
    csubstr encoded = this->to_arena(w);
    this->set_key(encoded);
    return encoded.len;
}

size_t NodeRef::set_val_serialized(c4::fmt::const_base64_wrapper w)
{
    _apply_seed();
    csubstr encoded = this->to_arena(w);
    this->set_val(encoded);
    return encoded.len;
}

} // namespace yml
} // namespace c4

#endif /* RYML_SINGLE_HDR_DEFINE_NOW */


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/node.cpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/preprocess.hpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/preprocess.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_YML_PREPROCESS_HPP_
#define _C4_YML_PREPROCESS_HPP_

/** @file preprocess.hpp Functions for preprocessing YAML prior to parsing. */

/** @defgroup Preprocessors Preprocessor functions
 *
 * These are the existing preprocessors:
 *
 * @code{.cpp}
 * size_t preprocess_json(csubstr json, substr buf)
 * size_t preprocess_rxmap(csubstr json, substr buf)
 * @endcode
 */

#ifndef _C4_YML_COMMON_HPP_
//included above:
//#include "./common.hpp"
#endif
// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/substr.hpp
//#include <c4/substr.hpp>
#if !defined(C4_SUBSTR_HPP_) && !defined(_C4_SUBSTR_HPP_)
#error "amalgamate: file c4/substr.hpp must have been included at this point"
#endif /* C4_SUBSTR_HPP_ */



namespace c4 {
namespace yml {

namespace detail {
using Preprocessor = size_t(csubstr, substr);
template<Preprocessor PP, class CharContainer>
substr preprocess_into_container(csubstr input, CharContainer *out)
{
    // try to write once. the preprocessor will stop writing at the end of
    // the container, but will process all the input to determine the
    // required container size.
    size_t sz = PP(input, to_substr(*out));
    // if the container size is not enough, resize, and run again in the
    // resized container
    if(sz > out->size())
    {
        out->resize(sz);
        sz = PP(input, to_substr(*out));
    }
    return to_substr(*out).first(sz);
}
} // namespace detail


//-----------------------------------------------------------------------------

/** @name preprocess_rxmap
 * Convert flow-type relaxed maps (with implicit bools) into strict YAML
 * flow map.
 *
 * @code{.yaml}
 * {a, b, c, d: [e, f], g: {a, b}}
 * # is converted into this:
 * {a: 1, b: 1, c: 1, d: [e, f], g: {a, b}}
 * @endcode

 * @note this is NOT recursive - conversion happens only in the top-level map
 * @param rxmap A relaxed map
 * @param buf output buffer
 * @param out output container
 */

//@{

/** Write into a given output buffer. This function is safe to call with
 * empty or small buffers; it won't write beyond the end of the buffer.
 *
 * @return the number of characters required for output
 */
RYML_EXPORT size_t preprocess_rxmap(csubstr rxmap, substr buf);


/** Write into an existing container. It is resized to contained the output.
 * @return a substr of the container
 * @overload preprocess_rxmap */
template<class CharContainer>
substr preprocess_rxmap(csubstr rxmap, CharContainer *out)
{
    return detail::preprocess_into_container<preprocess_rxmap>(rxmap, out);
}


/** Create a container with the result.
 * @overload preprocess_rxmap */
template<class CharContainer>
CharContainer preprocess_rxmap(csubstr rxmap)
{
    CharContainer out;
    preprocess_rxmap(rxmap, &out);
    return out;
}

//@}

} // namespace yml
} // namespace c4

#endif /* _C4_YML_PREPROCESS_HPP_ */


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/preprocess.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/preprocess.cpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/preprocess.cpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifdef RYML_SINGLE_HDR_DEFINE_NOW
// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/preprocess.hpp
//#include "c4/yml/preprocess.hpp"
#if !defined(C4_YML_PREPROCESS_HPP_) && !defined(_C4_YML_PREPROCESS_HPP_)
#error "amalgamate: file c4/yml/preprocess.hpp must have been included at this point"
#endif /* C4_YML_PREPROCESS_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/detail/parser_dbg.hpp
//#include "c4/yml/detail/parser_dbg.hpp"
#if !defined(C4_YML_DETAIL_PARSER_DBG_HPP_) && !defined(_C4_YML_DETAIL_PARSER_DBG_HPP_)
#error "amalgamate: file c4/yml/detail/parser_dbg.hpp must have been included at this point"
#endif /* C4_YML_DETAIL_PARSER_DBG_HPP_ */


/** @file preprocess.hpp Functions for preprocessing YAML prior to parsing. */

namespace c4 {
namespace yml {


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

namespace {
C4_ALWAYS_INLINE bool _is_idchar(char c)
{
    return (c >= 'a' && c <= 'z')
        || (c >= 'A' && c <= 'Z')
        || (c >= '0' && c <= '9')
        || (c == '_' || c == '-' || c == '~' || c == '$');
}

typedef enum { kReadPending = 0, kKeyPending = 1, kValPending = 2 } _ppstate;
C4_ALWAYS_INLINE _ppstate _next(_ppstate s)
{
    int n = (int)s + 1;
    return (_ppstate)(n <= (int)kValPending ? n : 0);
}
} // empty namespace


//-----------------------------------------------------------------------------

size_t preprocess_rxmap(csubstr s, substr buf)
{
    detail::_SubstrWriter writer(buf);
    _ppstate state = kReadPending;
    size_t last = 0;

    if(s.begins_with('{'))
    {
        RYML_CHECK(s.ends_with('}'));
        s = s.offs(1, 1);
    }

    writer.append('{');

    for(size_t i = 0; i < s.len; ++i)
    {
        const char curr = s[i];
        const char next = i+1 < s.len ? s[i+1] : '\0';

        if(curr == '\'' || curr == '"')
        {
            csubstr ss = s.sub(i).pair_range_esc(curr, '\\');
            i += static_cast<size_t>(ss.end() - (s.str + i));
            state = _next(state);
        }
        else if(state == kReadPending && _is_idchar(curr))
        {
            state = _next(state);
        }

        switch(state)
        {
        case kKeyPending:
        {
            if(curr == ':' && next == ' ')
            {
                state = _next(state);
            }
            else if(curr == ',' && next == ' ')
            {
                writer.append(s.range(last, i));
                writer.append(": 1, ");
                last = i + 2;
            }
            break;
        }
        case kValPending:
        {
            if(curr == '[' || curr == '{' || curr == '(')
            {
                csubstr ss = s.sub(i).pair_range_nested(curr, '\\');
                i += static_cast<size_t>(ss.end() - (s.str + i));
                state = _next(state);
            }
            else if(curr == ',' && next == ' ')
            {
                state = _next(state);
            }
            break;
        }
        default:
            // nothing to do
            break;
        }
    }

    writer.append(s.sub(last));
    if(state == kKeyPending)
        writer.append(": 1");
    writer.append('}');

    return writer.pos;
}


} // namespace yml
} // namespace c4

#endif /* RYML_SINGLE_HDR_DEFINE_NOW */


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/preprocess.cpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/detail/checks.hpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/detail/checks.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef C4_YML_DETAIL_CHECKS_HPP_
#define C4_YML_DETAIL_CHECKS_HPP_

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/tree.hpp
//#include "c4/yml/tree.hpp"
#if !defined(C4_YML_TREE_HPP_) && !defined(_C4_YML_TREE_HPP_)
#error "amalgamate: file c4/yml/tree.hpp must have been included at this point"
#endif /* C4_YML_TREE_HPP_ */


#ifdef __clang__
#   pragma clang diagnostic push
#elif defined(__GNUC__)
#   pragma GCC diagnostic push
#   pragma GCC diagnostic ignored "-Wtype-limits" // error: comparison of unsigned expression >= 0 is always true
#elif defined(_MSC_VER)
#   pragma warning(push)
#   pragma warning(disable: 4296/*expression is always 'boolean_value'*/)
#endif

namespace c4 {
namespace yml {


void check_invariants(Tree const& t, size_t node=NONE);
void check_free_list(Tree const& t);
void check_arena(Tree const& t);


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

inline void check_invariants(Tree const& t, size_t node)
{
    if(node == NONE)
    {
        if(t.size() == 0) return;
        node = t.root_id();
    }

    auto const& n = *t._p(node);
#ifdef RYML_DBG
    if(n.m_first_child != NONE || n.m_last_child != NONE)
    {
        printf("check(%zu): fc=%zu lc=%zu\n", node, n.m_first_child, n.m_last_child);
    }
    else
    {
        printf("check(%zu)\n", node);
    }
#endif

    C4_CHECK(n.m_parent != node);
    if(n.m_parent == NONE)
    {
        C4_CHECK(t.is_root(node));
    }
    else //if(n.m_parent != NONE)
    {
        C4_CHECK(t.has_child(n.m_parent, node));

        auto const& p = *t._p(n.m_parent);
        if(n.m_prev_sibling == NONE)
        {
            C4_CHECK(p.m_first_child == node);
            C4_CHECK(t.first_sibling(node) == node);
        }
        else
        {
            C4_CHECK(p.m_first_child != node);
            C4_CHECK(t.first_sibling(node) != node);
        }

        if(n.m_next_sibling == NONE)
        {
            C4_CHECK(p.m_last_child == node);
            C4_CHECK(t.last_sibling(node) == node);
        }
        else
        {
            C4_CHECK(p.m_last_child != node);
            C4_CHECK(t.last_sibling(node) != node);
        }
    }

    C4_CHECK(n.m_first_child != node);
    C4_CHECK(n.m_last_child != node);
    if(n.m_first_child != NONE || n.m_last_child != NONE)
    {
        C4_CHECK(n.m_first_child != NONE);
        C4_CHECK(n.m_last_child != NONE);
    }

    C4_CHECK(n.m_prev_sibling != node);
    C4_CHECK(n.m_next_sibling != node);
    if(n.m_prev_sibling != NONE)
    {
        C4_CHECK(t._p(n.m_prev_sibling)->m_next_sibling == node);
        C4_CHECK(t._p(n.m_prev_sibling)->m_prev_sibling != node);
    }
    if(n.m_next_sibling != NONE)
    {
        C4_CHECK(t._p(n.m_next_sibling)->m_prev_sibling == node);
        C4_CHECK(t._p(n.m_next_sibling)->m_next_sibling != node);
    }

    size_t count = 0;
    for(size_t i = n.m_first_child; i != NONE; i = t.next_sibling(i))
    {
#ifdef RYML_DBG
        printf("check(%zu):               descend to child[%zu]=%zu\n", node, count, i);
#endif
        auto const& ch = *t._p(i);
        C4_CHECK(ch.m_parent == node);
        C4_CHECK(ch.m_next_sibling != i);
        ++count;
    }
    C4_CHECK(count == t.num_children(node));

    if(n.m_prev_sibling == NONE && n.m_next_sibling == NONE)
    {
        if(n.m_parent != NONE)
        {
            C4_CHECK(t.num_children(n.m_parent) == 1);
            C4_CHECK(t.num_siblings(node) == 1);
        }
    }

    if(node == t.root_id())
    {
        C4_CHECK(t.size() == t.m_size);
        C4_CHECK(t.capacity() == t.m_cap);
        C4_CHECK(t.m_cap == t.m_size + t.slack());
        check_free_list(t);
        check_arena(t);
    }

    for(size_t i = t.first_child(node); i != NONE; i = t.next_sibling(i))
    {
        check_invariants(t, i);
    }
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

inline void check_free_list(Tree const& t)
{
    if(t.m_free_head == NONE)
    {
        C4_CHECK(t.m_free_tail == t.m_free_head);
        return;
    }

    C4_CHECK(t.m_free_head >= 0 && t.m_free_head < t.m_cap);
    C4_CHECK(t.m_free_tail >= 0 && t.m_free_tail < t.m_cap);

    auto const& head = *t._p(t.m_free_head);
    //auto const& tail = *t._p(t.m_free_tail);

    //C4_CHECK(head.m_prev_sibling == NONE);
    //C4_CHECK(tail.m_next_sibling == NONE);

    size_t count = 0;
    for(size_t i = t.m_free_head, prev = NONE; i != NONE; i = t._p(i)->m_next_sibling)
    {
        auto const& elm = *t._p(i);
        if(&elm != &head)
        {
            C4_CHECK(elm.m_prev_sibling == prev);
        }
        prev = i;
        ++count;
    }
    C4_CHECK(count == t.slack());
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

inline void check_arena(Tree const& t)
{
    C4_CHECK(t.m_arena.len == 0 || (t.m_arena_pos >= 0 && t.m_arena_pos <= t.m_arena.len));
    C4_CHECK(t.arena_size() == t.m_arena_pos);
    C4_CHECK(t.arena_slack() + t.m_arena_pos == t.m_arena.len);
}


} /* namespace yml */
} /* namespace c4 */

#ifdef __clang__
#   pragma clang diagnostic pop
#elif defined(__GNUC__)
#   pragma GCC diagnostic pop
#elif defined(_MSC_VER)
#   pragma warning(pop)
#endif

#endif /* C4_YML_DETAIL_CHECKS_HPP_ */


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/detail/checks.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/detail/print.hpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/detail/print.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef C4_YML_DETAIL_PRINT_HPP_
#define C4_YML_DETAIL_PRINT_HPP_

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/tree.hpp
//#include "c4/yml/tree.hpp"
#if !defined(C4_YML_TREE_HPP_) && !defined(_C4_YML_TREE_HPP_)
#error "amalgamate: file c4/yml/tree.hpp must have been included at this point"
#endif /* C4_YML_TREE_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/node.hpp
//#include "c4/yml/node.hpp"
#if !defined(C4_YML_NODE_HPP_) && !defined(_C4_YML_NODE_HPP_)
#error "amalgamate: file c4/yml/node.hpp must have been included at this point"
#endif /* C4_YML_NODE_HPP_ */



namespace c4 {
namespace yml {


inline size_t print_node(Tree const& p, size_t node, int level, size_t count, bool print_children)
{
    printf("[%zd]%*s[%zd] %p", count, (2*level), "", node, (void*)p.get(node));
    if(p.is_root(node))
    {
        printf(" [ROOT]");
    }
    printf(" %s:", p.type_str(node));
    if(p.has_key(node))
    {
        if(p.has_key_anchor(node))
        {
            csubstr ka = p.key_anchor(node);
            printf(" &%.*s", (int)ka.len, ka.str);
        }
        if(p.has_key_tag(node))
        {
            csubstr kt = p.key_tag(node);
            csubstr k  = p.key(node);
            printf(" %.*s '%.*s'", (int)kt.len, kt.str, (int)k.len, k.str);
        }
        else
        {
            csubstr k  = p.key(node);
            printf(" '%.*s'", (int)k.len, k.str);
        }
    }
    else
    {
        RYML_ASSERT( ! p.has_key_tag(node));
    }
    if(p.has_val(node))
    {
        if(p.has_val_tag(node))
        {
            csubstr vt = p.val_tag(node);
            csubstr v  = p.val(node);
            printf(" %.*s '%.*s'", (int)vt.len, vt.str, (int)v.len, v.str);
        }
        else
        {
            csubstr v  = p.val(node);
            printf(" '%.*s'", (int)v.len, v.str);
        }
    }
    else
    {
        if(p.has_val_tag(node))
        {
            csubstr vt = p.val_tag(node);
            printf(" %.*s", (int)vt.len, vt.str);
        }
    }
    if(p.has_val_anchor(node))
    {
        auto &a = p.val_anchor(node);
        printf(" valanchor='&%.*s'", (int)a.len, a.str);
    }
    printf(" (%zd sibs)", p.num_siblings(node));

    ++count;

    if(p.is_container(node))
    {
        printf(" %zd children:\n", p.num_children(node));
        if(print_children)
        {
            for(size_t i = p.first_child(node); i != NONE; i = p.next_sibling(i))
            {
                count = print_node(p, i, level+1, count, print_children);
            }
        }
    }
    else
    {
        printf("\n");
    }

    return count;
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

inline void print_node(ConstNodeRef const& p, int level=0)
{
    print_node(*p.tree(), p.id(), level, 0, true);
}


//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------

inline size_t print_tree(Tree const& p, size_t node=NONE)
{
    printf("--------------------------------------\n");
    size_t ret = 0;
    if(!p.empty())
    {
        if(node == NONE)
            node = p.root_id();
        ret = print_node(p, node, 0, 0, true);
    }
    printf("#nodes=%zd vs #printed=%zd\n", p.size(), ret);
    printf("--------------------------------------\n");
    return ret;
}


} /* namespace yml */
} /* namespace c4 */


#endif /* C4_YML_DETAIL_PRINT_HPP_ */


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/detail/print.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/c4/yml/yml.hpp
// https://github.com/biojppm/rapidyaml/src/c4/yml/yml.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _C4_YML_YML_HPP_
#define _C4_YML_YML_HPP_

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/tree.hpp
//#include "c4/yml/tree.hpp"
#if !defined(C4_YML_TREE_HPP_) && !defined(_C4_YML_TREE_HPP_)
#error "amalgamate: file c4/yml/tree.hpp must have been included at this point"
#endif /* C4_YML_TREE_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/node.hpp
//#include "c4/yml/node.hpp"
#if !defined(C4_YML_NODE_HPP_) && !defined(_C4_YML_NODE_HPP_)
#error "amalgamate: file c4/yml/node.hpp must have been included at this point"
#endif /* C4_YML_NODE_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/emit.hpp
//#include "c4/yml/emit.hpp"
#if !defined(C4_YML_EMIT_HPP_) && !defined(_C4_YML_EMIT_HPP_)
#error "amalgamate: file c4/yml/emit.hpp must have been included at this point"
#endif /* C4_YML_EMIT_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/parse.hpp
//#include "c4/yml/parse.hpp"
#if !defined(C4_YML_PARSE_HPP_) && !defined(_C4_YML_PARSE_HPP_)
#error "amalgamate: file c4/yml/parse.hpp must have been included at this point"
#endif /* C4_YML_PARSE_HPP_ */

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/preprocess.hpp
//#include "c4/yml/preprocess.hpp"
#if !defined(C4_YML_PREPROCESS_HPP_) && !defined(_C4_YML_PREPROCESS_HPP_)
#error "amalgamate: file c4/yml/preprocess.hpp must have been included at this point"
#endif /* C4_YML_PREPROCESS_HPP_ */


#endif // _C4_YML_YML_HPP_


// (end https://github.com/biojppm/rapidyaml/src/c4/yml/yml.hpp)



//********************************************************************************
//--------------------------------------------------------------------------------
// src/ryml.hpp
// https://github.com/biojppm/rapidyaml/src/ryml.hpp
//--------------------------------------------------------------------------------
//********************************************************************************

#ifndef _RYML_HPP_
#define _RYML_HPP_

// amalgamate: removed include of
// https://github.com/biojppm/rapidyaml/src/c4/yml/yml.hpp
//#include "c4/yml/yml.hpp"
#if !defined(C4_YML_YML_HPP_) && !defined(_C4_YML_YML_HPP_)
#error "amalgamate: file c4/yml/yml.hpp must have been included at this point"
#endif /* C4_YML_YML_HPP_ */


namespace ryml {
using namespace c4::yml;
using namespace c4;
}

#endif /* _RYML_HPP_ */


// (end https://github.com/biojppm/rapidyaml/src/ryml.hpp)

#endif /* _RYML_SINGLE_HEADER_AMALGAMATED_HPP_ */

