simdjson.h

/* auto-generated on Tue Aug  4 13:10:22 PDT 2020. Do not edit! */
/* begin file include/simdjson.h */
#ifndef SIMDJSON_H
#define SIMDJSON_H

/**
 * @mainpage
 *
 * Check the [README.md](https://github.com/lemire/simdjson/blob/master/README.md#simdjson--parsing-gigabytes-of-json-per-second).
 * 
 * Sample code. See https://github.com/simdjson/simdjson/blob/master/doc/basics.md for more examples.

    #include "simdjson.h"

    int main(void) {
      // load from `twitter.json` file:
      simdjson::dom::parser parser;
      simdjson::dom::element tweets = parser.load("twitter.json");
      std::cout << tweets["search_metadata"]["count"] << " results." << std::endl;

      // Parse and iterate through an array of objects
      auto abstract_json = R"( [
        {  "12345" : {"a":12.34, "b":56.78, "c": 9998877}   },
        {  "12545" : {"a":11.44, "b":12.78, "c": 11111111}  }
        ] )"_padded;
  
      for (simdjson::dom::object obj : parser.parse(abstract_json)) {
        for(const auto& key_value : obj) {
          cout << "key: " << key_value.key << " : ";
          simdjson::dom::object innerobj = key_value.value;
          cout << "a: " << double(innerobj["a"]) << ", ";
          cout << "b: " << double(innerobj["b"]) << ", ";
          cout << "c: " << int64_t(innerobj["c"]) << endl;
        }
      }
    }
 */

/* begin file include/simdjson/compiler_check.h */
#ifndef SIMDJSON_COMPILER_CHECK_H
#define SIMDJSON_COMPILER_CHECK_H

#ifndef __cplusplus
#error simdjson requires a C++ compiler
#endif

#ifndef SIMDJSON_CPLUSPLUS
#if defined(_MSVC_LANG) && !defined(__clang__)
#define SIMDJSON_CPLUSPLUS (_MSC_VER == 1900 ? 201103L : _MSVC_LANG)
#else
#define SIMDJSON_CPLUSPLUS __cplusplus
#endif
#endif

// C++ 17
#if !defined(SIMDJSON_CPLUSPLUS17) && (SIMDJSON_CPLUSPLUS >= 201703L)
#define SIMDJSON_CPLUSPLUS17 1
#endif

// C++ 14
#if !defined(SIMDJSON_CPLUSPLUS14) && (SIMDJSON_CPLUSPLUS >= 201402L)
#define SIMDJSON_CPLUSPLUS14 1
#endif

// C++ 11
#if !defined(SIMDJSON_CPLUSPLUS11) && (SIMDJSON_CPLUSPLUS >= 201103L)
#define SIMDJSON_CPLUSPLUS11 1
#endif

#ifndef SIMDJSON_CPLUSPLUS11
#error simdjson requires a compiler compliant with the C++11 standard
#endif

#endif // SIMDJSON_COMPILER_CHECK_H
/* end file include/simdjson/compiler_check.h */
/* begin file include/simdjson/common_defs.h */
#ifndef SIMDJSON_COMMON_DEFS_H
#define SIMDJSON_COMMON_DEFS_H

#include <cassert>
/* begin file include/simdjson/portability.h */
#ifndef SIMDJSON_PORTABILITY_H
#define SIMDJSON_PORTABILITY_H

#include <cstddef>
#include <cstdint>
#include <cstdlib>
#include <cfloat>
#include <cassert>
#ifndef _WIN32
// strcasecmp, strncasecmp 
#include <strings.h>
#endif

#ifdef _MSC_VER
#define SIMDJSON_VISUAL_STUDIO 1
/**
 * We want to differentiate carefully between
 * clang under visual studio and regular visual
 * studio.
 * 
 * Under clang for Windows, we enable:
 *  * target pragmas so that part and only part of the
 *     code gets compiled for advanced instructions.
 *  * computed gotos.
 *
 */
#ifdef __clang__
// clang under visual studio
#define SIMDJSON_CLANG_VISUAL_STUDIO 1
#else
// just regular visual studio (best guess)
#define SIMDJSON_REGULAR_VISUAL_STUDIO 1
#endif // __clang__
#endif // _MSC_VER

#ifdef SIMDJSON_REGULAR_VISUAL_STUDIO
// https://en.wikipedia.org/wiki/C_alternative_tokens
// This header should have no effect, except maybe
// under Visual Studio.
#include <iso646.h>
#endif

#if defined(__x86_64__) || defined(_M_AMD64)
#define SIMDJSON_IS_X86_64 1
#elif defined(__aarch64__) || defined(_M_ARM64)
#define SIMDJSON_IS_ARM64 1
#else 
#define SIMDJSON_IS_32BITS 1

// We do not support 32-bit platforms, but it can be
// handy to identify them.
#if defined(_M_IX86) || defined(__i386__)
#define SIMDJSON_IS_X86_32BITS 1
#elif defined(__arm__) || defined(_M_ARM)
#define SIMDJSON_IS_ARM_32BITS 1
#endif

#endif // defined(__x86_64__) || defined(_M_AMD64)

#ifdef SIMDJSON_IS_32BITS
#pragma message("The simdjson library is designed \
for 64-bit processors and it seems that you are not \
compiling for a known 64-bit platform. All fast kernels \
will be disabled and performance may be poor. Please \
use a 64-bit target such as x64 or 64-bit ARM.")
#endif // SIMDJSON_IS_32BITS

// this is almost standard?
#undef STRINGIFY_IMPLEMENTATION_
#undef STRINGIFY
#define STRINGIFY_IMPLEMENTATION_(a) #a
#define STRINGIFY(a) STRINGIFY_IMPLEMENTATION_(a)

#ifndef SIMDJSON_IMPLEMENTATION_FALLBACK
#define SIMDJSON_IMPLEMENTATION_FALLBACK 1
#endif

#if SIMDJSON_IS_ARM64
#ifndef SIMDJSON_IMPLEMENTATION_ARM64
#define SIMDJSON_IMPLEMENTATION_ARM64 1
#endif
#define SIMDJSON_IMPLEMENTATION_HASWELL 0
#define SIMDJSON_IMPLEMENTATION_WESTMERE 0
#endif // SIMDJSON_IS_ARM64

// Our fast kernels require 64-bit systems.
//
// On 32-bit x86, we lack 64-bit popcnt, lzcnt, blsr instructions. 
// Furthermore, the number of SIMD registers is reduced. 
//
// On 32-bit ARM, we would have smaller registers.
//
// The simdjson users should still have the fallback kernel. It is 
// slower, but it should run everywhere.
#if SIMDJSON_IS_X86_64
#ifndef SIMDJSON_IMPLEMENTATION_HASWELL
#define SIMDJSON_IMPLEMENTATION_HASWELL 1
#endif
#ifndef SIMDJSON_IMPLEMENTATION_WESTMERE
#define SIMDJSON_IMPLEMENTATION_WESTMERE 1
#endif
#define SIMDJSON_IMPLEMENTATION_ARM64 0
#endif // SIMDJSON_IS_X86_64

// We are going to use runtime dispatch.
#ifdef SIMDJSON_IS_X86_64
#ifdef __clang__
// clang does not have GCC push pop
// warning: clang attribute push can't be used within a namespace in clang up
// til 8.0 so SIMDJSON_TARGET_REGION and SIMDJSON_UNTARGET_REGION must be *outside* of a
// namespace.
#define SIMDJSON_TARGET_REGION(T)                                                       \
  _Pragma(STRINGIFY(                                                           \
      clang attribute push(__attribute__((target(T))), apply_to = function)))
#define SIMDJSON_UNTARGET_REGION _Pragma("clang attribute pop")
#elif defined(__GNUC__)
// GCC is easier
#define SIMDJSON_TARGET_REGION(T)                                                       \
  _Pragma("GCC push_options") _Pragma(STRINGIFY(GCC target(T)))
#define SIMDJSON_UNTARGET_REGION _Pragma("GCC pop_options")
#endif // clang then gcc

#endif // x86

// Default target region macros don't do anything.
#ifndef SIMDJSON_TARGET_REGION
#define SIMDJSON_TARGET_REGION(T)
#define SIMDJSON_UNTARGET_REGION
#endif

// Is threading enabled?
#if defined(BOOST_HAS_THREADS) || defined(_REENTRANT) || defined(_MT)
#ifndef SIMDJSON_THREADS_ENABLED
#define SIMDJSON_THREADS_ENABLED
#endif
#endif

// workaround for large stack sizes under -O0.
// https://github.com/simdjson/simdjson/issues/691
#ifdef __APPLE__
#ifndef __OPTIMIZE__
// Apple systems have small stack sizes in secondary threads.
// Lack of compiler optimization may generate high stack usage.
// Users may want to disable threads for safety, but only when
// in debug mode which we detect by the fact that the __OPTIMIZE__
// macro is not defined.
#undef SIMDJSON_THREADS_ENABLED
#endif
#endif


#if SIMDJSON_DO_NOT_USE_THREADS_NO_MATTER_WHAT
// No matter what happened, we undefine SIMDJSON_THREADS_ENABLED and so disable threads.
#undef SIMDJSON_THREADS_ENABLED
#endif


#if defined(__clang__)
#define NO_SANITIZE_UNDEFINED __attribute__((no_sanitize("undefined")))
#elif defined(__GNUC__)
#define NO_SANITIZE_UNDEFINED __attribute__((no_sanitize_undefined))
#else
#define NO_SANITIZE_UNDEFINED
#endif

#ifdef SIMDJSON_VISUAL_STUDIO
// This is one case where we do not distinguish between
// regular visual studio and clang under visual studio.
// clang under Windows has _stricmp (like visual studio) but not strcasecmp (as clang normally has)
#define simdjson_strcasecmp _stricmp
#define simdjson_strncasecmp _strnicmp
#else
// The strcasecmp, strncasecmp, and strcasestr functions do not work with multibyte strings (e.g. UTF-8).
// So they are only useful for ASCII in our context.
// https://www.gnu.org/software/libunistring/manual/libunistring.html#char-_002a-strings
#define simdjson_strcasecmp strcasecmp
#define simdjson_strncasecmp strncasecmp
#endif

#ifdef NDEBUG

#ifdef SIMDJSON_VISUAL_STUDIO
#define SIMDJSON_UNREACHABLE() __assume(0)
#define SIMDJSON_ASSUME(COND) __assume(COND)
#else
#define SIMDJSON_UNREACHABLE() __builtin_unreachable();
#define SIMDJSON_ASSUME(COND) do { if (!(COND)) __builtin_unreachable(); } while (0)
#endif

#else // NDEBUG

#define SIMDJSON_UNREACHABLE() assert(0);
#define SIMDJSON_ASSUME(COND) assert(COND)

#endif

#endif // SIMDJSON_PORTABILITY_H
/* end file include/simdjson/portability.h */

namespace simdjson {

#ifndef SIMDJSON_EXCEPTIONS
#if __cpp_exceptions
#define SIMDJSON_EXCEPTIONS 1
#else
#define SIMDJSON_EXCEPTIONS 0
#endif
#endif

/** The maximum document size supported by simdjson. */
constexpr size_t SIMDJSON_MAXSIZE_BYTES = 0xFFFFFFFF;

/**
 * The amount of padding needed in a buffer to parse JSON.
 *
 * the input buf should be readable up to buf + SIMDJSON_PADDING
 * this is a stopgap; there should be a better description of the
 * main loop and its behavior that abstracts over this
 * See https://github.com/lemire/simdjson/issues/174
 */
constexpr size_t SIMDJSON_PADDING = 32;

/**
 * By default, simdjson supports this many nested objects and arrays.
 *
 * This is the default for parser::max_depth().
 */
constexpr size_t DEFAULT_MAX_DEPTH = 1024;

} // namespace simdjson

#if defined(__GNUC__)
  // Marks a block with a name so that MCA analysis can see it.
  #define BEGIN_DEBUG_BLOCK(name) __asm volatile("# LLVM-MCA-BEGIN " #name);
  #define END_DEBUG_BLOCK(name) __asm volatile("# LLVM-MCA-END " #name);
  #define DEBUG_BLOCK(name, block) BEGIN_DEBUG_BLOCK(name); block; END_DEBUG_BLOCK(name);
#else
  #define BEGIN_DEBUG_BLOCK(name)
  #define END_DEBUG_BLOCK(name)
  #define DEBUG_BLOCK(name, block)
#endif

#if !defined(SIMDJSON_REGULAR_VISUAL_STUDIO) && !defined(SIMDJSON_NO_COMPUTED_GOTO)
  // We assume here that *only* regular visual studio
  // does not support computed gotos.
  // Implemented using Labels as Values which works in GCC and CLANG (and maybe
  // also in Intel's compiler), but won't work in MSVC.
  // Compute gotos are good for performance, enable them if you can.
  #define SIMDJSON_USE_COMPUTED_GOTO
#endif

// Align to N-byte boundary
#define ROUNDUP_N(a, n) (((a) + ((n)-1)) & ~((n)-1))
#define ROUNDDOWN_N(a, n) ((a) & ~((n)-1))

#define ISALIGNED_N(ptr, n) (((uintptr_t)(ptr) & ((n)-1)) == 0)

#if defined(SIMDJSON_REGULAR_VISUAL_STUDIO)

  #define really_inline __forceinline
  #define never_inline __declspec(noinline)

  #define UNUSED
  #define WARN_UNUSED

  #ifndef likely
  #define likely(x) x
  #endif
  #ifndef unlikely
  #define unlikely(x) x
  #endif

  #define SIMDJSON_PUSH_DISABLE_WARNINGS __pragma(warning( push ))
  #define SIMDJSON_PUSH_DISABLE_ALL_WARNINGS __pragma(warning( push, 0 ))
  #define SIMDJSON_DISABLE_VS_WARNING(WARNING_NUMBER) __pragma(warning( disable : WARNING_NUMBER ))
  // Get rid of Intellisense-only warnings (Code Analysis)
  // Though __has_include is C++17, it is supported in Visual Studio 2017 or better (_MSC_VER>=1910).
  #if defined(_MSC_VER) && (_MSC_VER>=1910) 
  #if __has_include(<CppCoreCheck\Warnings.h>)
  #include <CppCoreCheck\Warnings.h>
  #define SIMDJSON_DISABLE_UNDESIRED_WARNINGS SIMDJSON_DISABLE_VS_WARNING(ALL_CPPCORECHECK_WARNINGS)
  #endif
  #endif

  #ifndef SIMDJSON_DISABLE_UNDESIRED_WARNINGS
  #define SIMDJSON_DISABLE_UNDESIRED_WARNINGS
  #endif

  #define SIMDJSON_DISABLE_DEPRECATED_WARNING SIMDJSON_DISABLE_VS_WARNING(4996)
  #define SIMDJSON_POP_DISABLE_WARNINGS __pragma(warning( pop ))

#else // SIMDJSON_REGULAR_VISUAL_STUDIO

  #define really_inline inline __attribute__((always_inline))
  #define never_inline inline __attribute__((noinline))

  #define UNUSED __attribute__((unused))
  #define WARN_UNUSED __attribute__((warn_unused_result))

  #ifndef likely
  #define likely(x) __builtin_expect(!!(x), 1)
  #endif
  #ifndef unlikely
  #define unlikely(x) __builtin_expect(!!(x), 0)
  #endif

  #define SIMDJSON_PUSH_DISABLE_WARNINGS _Pragma("GCC diagnostic push")
  // gcc doesn't seem to disable all warnings with all and extra, add warnings here as necessary
  #define SIMDJSON_PUSH_DISABLE_ALL_WARNINGS SIMDJSON_PUSH_DISABLE_WARNINGS \
    SIMDJSON_DISABLE_GCC_WARNING(-Weffc++) \
    SIMDJSON_DISABLE_GCC_WARNING(-Wall) \
    SIMDJSON_DISABLE_GCC_WARNING(-Wconversion) \
    SIMDJSON_DISABLE_GCC_WARNING(-Wextra) \
    SIMDJSON_DISABLE_GCC_WARNING(-Wattributes) \
    SIMDJSON_DISABLE_GCC_WARNING(-Wimplicit-fallthrough) \
    SIMDJSON_DISABLE_GCC_WARNING(-Wnon-virtual-dtor) \
    SIMDJSON_DISABLE_GCC_WARNING(-Wreturn-type) \
    SIMDJSON_DISABLE_GCC_WARNING(-Wshadow) \
    SIMDJSON_DISABLE_GCC_WARNING(-Wunused-parameter) \
    SIMDJSON_DISABLE_GCC_WARNING(-Wunused-variable)
  #define SIMDJSON_PRAGMA(P) _Pragma(#P)
  #define SIMDJSON_DISABLE_GCC_WARNING(WARNING) SIMDJSON_PRAGMA(GCC diagnostic ignored #WARNING)
  #if defined(SIMDJSON_CLANG_VISUAL_STUDIO)
  #define SIMDJSON_DISABLE_UNDESIRED_WARNINGS SIMDJSON_DISABLE_GCC_WARNING(-Wmicrosoft-include)
  #else
  #define SIMDJSON_DISABLE_UNDESIRED_WARNINGS
  #endif
  #define SIMDJSON_DISABLE_DEPRECATED_WARNING SIMDJSON_DISABLE_GCC_WARNING(-Wdeprecated-declarations)
  #define SIMDJSON_POP_DISABLE_WARNINGS _Pragma("GCC diagnostic pop")



#endif // MSC_VER

#if defined(SIMDJSON_VISUAL_STUDIO)
    /**
     * It does not matter here whether you are using
     * the regular visual studio or clang under visual
     * studio.
     */
    #if SIMDJSON_USING_LIBRARY
    #define SIMDJSON_DLLIMPORTEXPORT __declspec(dllimport)
    #else
    #define SIMDJSON_DLLIMPORTEXPORT __declspec(dllexport)
    #endif
#else
    #define SIMDJSON_DLLIMPORTEXPORT
#endif

// C++17 requires string_view.
#if SIMDJSON_CPLUSPLUS17
#define SIMDJSON_HAS_STRING_VIEW
#endif

// This macro (__cpp_lib_string_view) has to be defined
// for C++17 and better, but if it is otherwise defined,
// we are going to assume that string_view is available
// even if we do not have C++17 support.
#ifdef __cpp_lib_string_view
#define SIMDJSON_HAS_STRING_VIEW
#endif

// Some systems have string_view even if we do not have C++17 support,
// and even if __cpp_lib_string_view is undefined, it is the case
// with Apple clang version 11.
// We must handle it. *This is important.*
#ifndef SIMDJSON_HAS_STRING_VIEW
#if defined __has_include
// do not combine the next #if with the previous one (unsafe)
#if __has_include (<string_view>)
// now it is safe to trigger the include
#include <string_view> // though the file is there, it does not follow that we got the implementation
#if defined(_LIBCPP_STRING_VIEW)
// Ah! So we under libc++ which under its Library Fundamentals Technical Specification, which preceeded C++17,
// included string_view.
// This means that we have string_view *even though* we may not have C++17.
#define SIMDJSON_HAS_STRING_VIEW
#endif // _LIBCPP_STRING_VIEW
#endif // __has_include (<string_view>)
#endif // defined __has_include
#endif // def SIMDJSON_HAS_STRING_VIEW
// end of complicated but important routine to try to detect string_view.

//
// Backfill std::string_view using nonstd::string_view on systems where
// we expect that string_view is missing. Important: if we get this wrong,
// we will end up with two string_view definitions and potential trouble.
// That is why we work so hard above to avoid it.
//
#ifndef SIMDJSON_HAS_STRING_VIEW
SIMDJSON_PUSH_DISABLE_ALL_WARNINGS
/* begin file include/simdjson/nonstd/string_view.hpp */
// Copyright 2017-2019 by Martin Moene
//
// string-view lite, a C++17-like string_view for C++98 and later.
// For more information see https://github.com/martinmoene/string-view-lite
//
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

#pragma once

#ifndef NONSTD_SV_LITE_H_INCLUDED
#define NONSTD_SV_LITE_H_INCLUDED

#define string_view_lite_MAJOR  1
#define string_view_lite_MINOR  4
#define string_view_lite_PATCH  0

#define string_view_lite_VERSION  nssv_STRINGIFY(string_view_lite_MAJOR) "." nssv_STRINGIFY(string_view_lite_MINOR) "." nssv_STRINGIFY(string_view_lite_PATCH)

#define nssv_STRINGIFY(  x )  nssv_STRINGIFY_( x )
#define nssv_STRINGIFY_( x )  #x

// string-view lite configuration:

#define nssv_STRING_VIEW_DEFAULT  0
#define nssv_STRING_VIEW_NONSTD   1
#define nssv_STRING_VIEW_STD      2

#if !defined( nssv_CONFIG_SELECT_STRING_VIEW )
# define nssv_CONFIG_SELECT_STRING_VIEW  ( nssv_HAVE_STD_STRING_VIEW ? nssv_STRING_VIEW_STD : nssv_STRING_VIEW_NONSTD )
#endif

#if defined( nssv_CONFIG_SELECT_STD_STRING_VIEW ) || defined( nssv_CONFIG_SELECT_NONSTD_STRING_VIEW )
# error nssv_CONFIG_SELECT_STD_STRING_VIEW and nssv_CONFIG_SELECT_NONSTD_STRING_VIEW are deprecated and removed, please use nssv_CONFIG_SELECT_STRING_VIEW=nssv_STRING_VIEW_...
#endif

#ifndef  nssv_CONFIG_STD_SV_OPERATOR
# define nssv_CONFIG_STD_SV_OPERATOR  0
#endif

#ifndef  nssv_CONFIG_USR_SV_OPERATOR
# define nssv_CONFIG_USR_SV_OPERATOR  1
#endif

#ifdef   nssv_CONFIG_CONVERSION_STD_STRING
# define nssv_CONFIG_CONVERSION_STD_STRING_CLASS_METHODS   nssv_CONFIG_CONVERSION_STD_STRING
# define nssv_CONFIG_CONVERSION_STD_STRING_FREE_FUNCTIONS  nssv_CONFIG_CONVERSION_STD_STRING
#endif

#ifndef  nssv_CONFIG_CONVERSION_STD_STRING_CLASS_METHODS
# define nssv_CONFIG_CONVERSION_STD_STRING_CLASS_METHODS  1
#endif

#ifndef  nssv_CONFIG_CONVERSION_STD_STRING_FREE_FUNCTIONS
# define nssv_CONFIG_CONVERSION_STD_STRING_FREE_FUNCTIONS  1
#endif

// Control presence of exception handling (try and auto discover):

#ifndef nssv_CONFIG_NO_EXCEPTIONS
# if defined(__cpp_exceptions) || defined(__EXCEPTIONS) || defined(_CPPUNWIND)
#  define nssv_CONFIG_NO_EXCEPTIONS  0
# else
#  define nssv_CONFIG_NO_EXCEPTIONS  1
# endif
#endif

// C++ language version detection (C++20 is speculative):
// Note: VC14.0/1900 (VS2015) lacks too much from C++14.

#ifndef   nssv_CPLUSPLUS
# if defined(_MSVC_LANG ) && !defined(__clang__)
#  define nssv_CPLUSPLUS  (_MSC_VER == 1900 ? 201103L : _MSVC_LANG )
# else
#  define nssv_CPLUSPLUS  __cplusplus
# endif
#endif

#define nssv_CPP98_OR_GREATER  ( nssv_CPLUSPLUS >= 199711L )
#define nssv_CPP11_OR_GREATER  ( nssv_CPLUSPLUS >= 201103L )
#define nssv_CPP11_OR_GREATER_ ( nssv_CPLUSPLUS >= 201103L )
#define nssv_CPP14_OR_GREATER  ( nssv_CPLUSPLUS >= 201402L )
#define nssv_CPP17_OR_GREATER  ( nssv_CPLUSPLUS >= 201703L )
#define nssv_CPP20_OR_GREATER  ( nssv_CPLUSPLUS >= 202000L )

// use C++17 std::string_view if available and requested:

#if nssv_CPP17_OR_GREATER && defined(__has_include )
# if __has_include( <string_view> )
#  define nssv_HAVE_STD_STRING_VIEW  1
# else
#  define nssv_HAVE_STD_STRING_VIEW  0
# endif
#else
# define  nssv_HAVE_STD_STRING_VIEW  0
#endif

#define  nssv_USES_STD_STRING_VIEW  ( (nssv_CONFIG_SELECT_STRING_VIEW == nssv_STRING_VIEW_STD) || ((nssv_CONFIG_SELECT_STRING_VIEW == nssv_STRING_VIEW_DEFAULT) && nssv_HAVE_STD_STRING_VIEW) )

#define nssv_HAVE_STARTS_WITH ( nssv_CPP20_OR_GREATER || !nssv_USES_STD_STRING_VIEW )
#define nssv_HAVE_ENDS_WITH     nssv_HAVE_STARTS_WITH

//
// Use C++17 std::string_view:
//

#if nssv_USES_STD_STRING_VIEW

#include <string_view>

// Extensions for std::string:

#if nssv_CONFIG_CONVERSION_STD_STRING_FREE_FUNCTIONS

namespace nonstd {

template< class CharT, class Traits, class Allocator = std::allocator<CharT> >
std::basic_string<CharT, Traits, Allocator>
to_string( std::basic_string_view<CharT, Traits> v, Allocator const & a = Allocator() )
{
    return std::basic_string<CharT,Traits, Allocator>( v.begin(), v.end(), a );
}

template< class CharT, class Traits, class Allocator >
std::basic_string_view<CharT, Traits>
to_string_view( std::basic_string<CharT, Traits, Allocator> const & s )
{
    return std::basic_string_view<CharT, Traits>( s.data(), s.size() );
}

// Literal operators sv and _sv:

#if nssv_CONFIG_STD_SV_OPERATOR

using namespace std::literals::string_view_literals;

#endif

#if nssv_CONFIG_USR_SV_OPERATOR

inline namespace literals {
inline namespace string_view_literals {


constexpr std::string_view operator "" _sv( const char* str, size_t len ) noexcept  // (1)
{
    return std::string_view{ str, len };
}

constexpr std::u16string_view operator "" _sv( const char16_t* str, size_t len ) noexcept  // (2)
{
    return std::u16string_view{ str, len };
}

constexpr std::u32string_view operator "" _sv( const char32_t* str, size_t len ) noexcept  // (3)
{
    return std::u32string_view{ str, len };
}

constexpr std::wstring_view operator "" _sv( const wchar_t* str, size_t len ) noexcept  // (4)
{
    return std::wstring_view{ str, len };
}

}} // namespace literals::string_view_literals

#endif // nssv_CONFIG_USR_SV_OPERATOR

} // namespace nonstd

#endif // nssv_CONFIG_CONVERSION_STD_STRING_FREE_FUNCTIONS

namespace nonstd {

using std::string_view;
using std::wstring_view;
using std::u16string_view;
using std::u32string_view;
using std::basic_string_view;

// literal "sv" and "_sv", see above

using std::operator==;
using std::operator!=;
using std::operator<;
using std::operator<=;
using std::operator>;
using std::operator>=;

using std::operator<<;

} // namespace nonstd

#else // nssv_HAVE_STD_STRING_VIEW

//
// Before C++17: use string_view lite:
//

// Compiler versions:
//
// MSVC++  6.0  _MSC_VER == 1200  nssv_COMPILER_MSVC_VERSION ==  60  (Visual Studio 6.0)
// MSVC++  7.0  _MSC_VER == 1300  nssv_COMPILER_MSVC_VERSION ==  70  (Visual Studio .NET 2002)
// MSVC++  7.1  _MSC_VER == 1310  nssv_COMPILER_MSVC_VERSION ==  71  (Visual Studio .NET 2003)
// MSVC++  8.0  _MSC_VER == 1400  nssv_COMPILER_MSVC_VERSION ==  80  (Visual Studio 2005)
// MSVC++  9.0  _MSC_VER == 1500  nssv_COMPILER_MSVC_VERSION ==  90  (Visual Studio 2008)
// MSVC++ 10.0  _MSC_VER == 1600  nssv_COMPILER_MSVC_VERSION == 100  (Visual Studio 2010)
// MSVC++ 11.0  _MSC_VER == 1700  nssv_COMPILER_MSVC_VERSION == 110  (Visual Studio 2012)
// MSVC++ 12.0  _MSC_VER == 1800  nssv_COMPILER_MSVC_VERSION == 120  (Visual Studio 2013)
// MSVC++ 14.0  _MSC_VER == 1900  nssv_COMPILER_MSVC_VERSION == 140  (Visual Studio 2015)
// MSVC++ 14.1  _MSC_VER >= 1910  nssv_COMPILER_MSVC_VERSION == 141  (Visual Studio 2017)
// MSVC++ 14.2  _MSC_VER >= 1920  nssv_COMPILER_MSVC_VERSION == 142  (Visual Studio 2019)

#if defined(_MSC_VER ) && !defined(__clang__)
# define nssv_COMPILER_MSVC_VER      (_MSC_VER )
# define nssv_COMPILER_MSVC_VERSION  (_MSC_VER / 10 - 10 * ( 5 + (_MSC_VER < 1900 ) ) )
#else
# define nssv_COMPILER_MSVC_VER      0
# define nssv_COMPILER_MSVC_VERSION  0
#endif

#define nssv_COMPILER_VERSION( major, minor, patch )  ( 10 * ( 10 * (major) + (minor) ) + (patch) )

#if defined(__clang__)
# define nssv_COMPILER_CLANG_VERSION  nssv_COMPILER_VERSION(__clang_major__, __clang_minor__, __clang_patchlevel__)
#else
# define nssv_COMPILER_CLANG_VERSION    0
#endif

#if defined(__GNUC__) && !defined(__clang__)
# define nssv_COMPILER_GNUC_VERSION  nssv_COMPILER_VERSION(__GNUC__, __GNUC_MINOR__, __GNUC_PATCHLEVEL__)
#else
# define nssv_COMPILER_GNUC_VERSION    0
#endif

// half-open range [lo..hi):
#define nssv_BETWEEN( v, lo, hi ) ( (lo) <= (v) && (v) < (hi) )

// Presence of language and library features:

#ifdef _HAS_CPP0X
# define nssv_HAS_CPP0X  _HAS_CPP0X
#else
# define nssv_HAS_CPP0X  0
#endif

// Unless defined otherwise below, consider VC14 as C++11 for variant-lite:

#if nssv_COMPILER_MSVC_VER >= 1900
# undef  nssv_CPP11_OR_GREATER
# define nssv_CPP11_OR_GREATER  1
#endif

#define nssv_CPP11_90   (nssv_CPP11_OR_GREATER_ || nssv_COMPILER_MSVC_VER >= 1500)
#define nssv_CPP11_100  (nssv_CPP11_OR_GREATER_ || nssv_COMPILER_MSVC_VER >= 1600)
#define nssv_CPP11_110  (nssv_CPP11_OR_GREATER_ || nssv_COMPILER_MSVC_VER >= 1700)
#define nssv_CPP11_120  (nssv_CPP11_OR_GREATER_ || nssv_COMPILER_MSVC_VER >= 1800)
#define nssv_CPP11_140  (nssv_CPP11_OR_GREATER_ || nssv_COMPILER_MSVC_VER >= 1900)
#define nssv_CPP11_141  (nssv_CPP11_OR_GREATER_ || nssv_COMPILER_MSVC_VER >= 1910)

#define nssv_CPP14_000  (nssv_CPP14_OR_GREATER)
#define nssv_CPP17_000  (nssv_CPP17_OR_GREATER)

// Presence of C++11 language features:

#define nssv_HAVE_CONSTEXPR_11          nssv_CPP11_140
#define nssv_HAVE_EXPLICIT_CONVERSION   nssv_CPP11_140
#define nssv_HAVE_INLINE_NAMESPACE      nssv_CPP11_140
#define nssv_HAVE_NOEXCEPT              nssv_CPP11_140
#define nssv_HAVE_NULLPTR               nssv_CPP11_100
#define nssv_HAVE_REF_QUALIFIER         nssv_CPP11_140
#define nssv_HAVE_UNICODE_LITERALS      nssv_CPP11_140
#define nssv_HAVE_USER_DEFINED_LITERALS nssv_CPP11_140
#define nssv_HAVE_WCHAR16_T             nssv_CPP11_100
#define nssv_HAVE_WCHAR32_T             nssv_CPP11_100

#if ! ( ( nssv_CPP11_OR_GREATER && nssv_COMPILER_CLANG_VERSION ) || nssv_BETWEEN( nssv_COMPILER_CLANG_VERSION, 300, 400 ) )
# define nssv_HAVE_STD_DEFINED_LITERALS  nssv_CPP11_140
#else
# define nssv_HAVE_STD_DEFINED_LITERALS  0
#endif

// Presence of C++14 language features:

#define nssv_HAVE_CONSTEXPR_14          nssv_CPP14_000

// Presence of C++17 language features:

#define nssv_HAVE_NODISCARD             nssv_CPP17_000

// Presence of C++ library features:

#define nssv_HAVE_STD_HASH              nssv_CPP11_120

// C++ feature usage:

#if nssv_HAVE_CONSTEXPR_11
# define nssv_constexpr  constexpr
#else
# define nssv_constexpr  /*constexpr*/
#endif

#if  nssv_HAVE_CONSTEXPR_14
# define nssv_constexpr14  constexpr
#else
# define nssv_constexpr14  /*constexpr*/
#endif

#if nssv_HAVE_EXPLICIT_CONVERSION
# define nssv_explicit  explicit
#else
# define nssv_explicit  /*explicit*/
#endif

#if nssv_HAVE_INLINE_NAMESPACE
# define nssv_inline_ns  inline
#else
# define nssv_inline_ns  /*inline*/
#endif

#if nssv_HAVE_NOEXCEPT
# define nssv_noexcept  noexcept
#else
# define nssv_noexcept  /*noexcept*/
#endif

//#if nssv_HAVE_REF_QUALIFIER
//# define nssv_ref_qual  &
//# define nssv_refref_qual  &&
//#else
//# define nssv_ref_qual  /*&*/
//# define nssv_refref_qual  /*&&*/
//#endif

#if nssv_HAVE_NULLPTR
# define nssv_nullptr  nullptr
#else
# define nssv_nullptr  NULL
#endif

#if nssv_HAVE_NODISCARD
# define nssv_nodiscard  [[nodiscard]]
#else
# define nssv_nodiscard  /*[[nodiscard]]*/
#endif

// Additional includes:

#include <algorithm>
#include <cassert>
#include <iterator>
#include <limits>
#include <ostream>
#include <string>   // std::char_traits<>

#if ! nssv_CONFIG_NO_EXCEPTIONS
# include <stdexcept>
#endif

#if nssv_CPP11_OR_GREATER
# include <type_traits>
#endif

// Clang, GNUC, MSVC warning suppression macros:

#if defined(__clang__)
# pragma clang diagnostic ignored "-Wreserved-user-defined-literal"
# pragma clang diagnostic push
# pragma clang diagnostic ignored "-Wuser-defined-literals"
#elif defined(__GNUC__)
# pragma  GCC  diagnostic push
# pragma  GCC  diagnostic ignored "-Wliteral-suffix"
#endif // __clang__

#if nssv_COMPILER_MSVC_VERSION >= 140
# define nssv_SUPPRESS_MSGSL_WARNING(expr)        [[gsl::suppress(expr)]]
# define nssv_SUPPRESS_MSVC_WARNING(code, descr)  __pragma(warning(suppress: code) )
# define nssv_DISABLE_MSVC_WARNINGS(codes)        __pragma(warning(push))  __pragma(warning(disable: codes))
#else
# define nssv_SUPPRESS_MSGSL_WARNING(expr)
# define nssv_SUPPRESS_MSVC_WARNING(code, descr)
# define nssv_DISABLE_MSVC_WARNINGS(codes)
#endif

#if defined(__clang__)
# define nssv_RESTORE_WARNINGS()  _Pragma("clang diagnostic pop")
#elif defined(__GNUC__)
# define nssv_RESTORE_WARNINGS()  _Pragma("GCC diagnostic pop")
#elif nssv_COMPILER_MSVC_VERSION >= 140
# define nssv_RESTORE_WARNINGS()  __pragma(warning(pop ))
#else
# define nssv_RESTORE_WARNINGS()
#endif

// Suppress the following MSVC (GSL) warnings:
// - C4455, non-gsl   : 'operator ""sv': literal suffix identifiers that do not
//                      start with an underscore are reserved
// - C26472, gsl::t.1 : don't use a static_cast for arithmetic conversions;
//                      use brace initialization, gsl::narrow_cast or gsl::narow
// - C26481: gsl::b.1 : don't use pointer arithmetic. Use span instead

nssv_DISABLE_MSVC_WARNINGS( 4455 26481 26472 )
//nssv_DISABLE_CLANG_WARNINGS( "-Wuser-defined-literals" )
//nssv_DISABLE_GNUC_WARNINGS( -Wliteral-suffix )

namespace nonstd { namespace sv_lite {

#if nssv_CPP11_OR_GREATER

namespace detail {

#if nssv_CPP14_OR_GREATER

template< typename CharT >
inline constexpr std::size_t length( CharT * s, std::size_t result = 0 )
{
    CharT * v = s;
    std::size_t r = result;
    while ( *v != '\0' ) {
       ++v;
       ++r;
    }
    return r;
}

#else // nssv_CPP14_OR_GREATER

// Expect tail call optimization to make length() non-recursive:

template< typename CharT >
inline constexpr std::size_t length( CharT * s, std::size_t result = 0 )
{
    return *s == '\0' ? result : length( s + 1, result + 1 );
}

#endif // nssv_CPP14_OR_GREATER

} // namespace detail

#endif // nssv_CPP11_OR_GREATER

template
<
    class CharT,
    class Traits = std::char_traits<CharT>
>
class basic_string_view;

//
// basic_string_view:
//

template
<
    class CharT,
    class Traits /* = std::char_traits<CharT> */
>
class basic_string_view
{
public:
    // Member types:

    typedef Traits traits_type;
    typedef CharT  value_type;

    typedef CharT       * pointer;
    typedef CharT const * const_pointer;
    typedef CharT       & reference;
    typedef CharT const & const_reference;

    typedef const_pointer iterator;
    typedef const_pointer const_iterator;
    typedef std::reverse_iterator< const_iterator > reverse_iterator;
    typedef	std::reverse_iterator< const_iterator > const_reverse_iterator;

    typedef std::size_t     size_type;
    typedef std::ptrdiff_t  difference_type;

    // 24.4.2.1 Construction and assignment:

    nssv_constexpr basic_string_view() nssv_noexcept
        : data_( nssv_nullptr )
        , size_( 0 )
    {}

#if nssv_CPP11_OR_GREATER
    nssv_constexpr basic_string_view( basic_string_view const & other ) nssv_noexcept = default;
#else
    nssv_constexpr basic_string_view( basic_string_view const & other ) nssv_noexcept
        : data_( other.data_)
        , size_( other.size_)
    {}
#endif

    nssv_constexpr basic_string_view( CharT const * s, size_type count ) nssv_noexcept // non-standard noexcept
        : data_( s )
        , size_( count )
    {}

    nssv_constexpr basic_string_view( CharT const * s) nssv_noexcept // non-standard noexcept
        : data_( s )
#if nssv_CPP17_OR_GREATER
        , size_( Traits::length(s) )
#elif nssv_CPP11_OR_GREATER
        , size_( detail::length(s) )
#else
        , size_( Traits::length(s) )
#endif
    {}

    // Assignment:

#if nssv_CPP11_OR_GREATER
    nssv_constexpr14 basic_string_view & operator=( basic_string_view const & other ) nssv_noexcept = default;
#else
    nssv_constexpr14 basic_string_view & operator=( basic_string_view const & other ) nssv_noexcept
    {
        data_ = other.data_;
        size_ = other.size_;
        return *this;
    }
#endif

    // 24.4.2.2 Iterator support:

    nssv_constexpr const_iterator begin()  const nssv_noexcept { return data_;         }
    nssv_constexpr const_iterator end()    const nssv_noexcept { return data_ + size_; }