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Differential D145590 Diff 505163 libcxx/include/charconv

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libcxx/include/charconv

Show First 20 Lines • Show All 61 Lines • ▼ Show 20 Lines	namespace std {

constexpr from_chars_result from_chars(const char* first, const char* last,		constexpr from_chars_result from_chars(const char* first, const char* last,
see below& value, int base = 10); // constexpr since C++23		see below& value, int base = 10); // constexpr since C++23

} // namespace std		} // namespace std

*/		*/

#include <__algorithm/copy_n.h>
#include <__assert> // all public C++ headers provide the assertion handler		#include <__assert> // all public C++ headers provide the assertion handler
#include <__availability>
#include <__bit/countl.h>
#include <__charconv/chars_format.h>		#include <__charconv/chars_format.h>
		#include <__charconv/from_chars_integral.h>
#include <__charconv/from_chars_result.h>		#include <__charconv/from_chars_result.h>
#include <__charconv/tables.h>		#include <__charconv/tables.h>
		#include <__charconv/to_chars.h>
#include <__charconv/to_chars_base_10.h>		#include <__charconv/to_chars_base_10.h>
		#include <__charconv/to_chars_floating_point.h>
		#include <__charconv/to_chars_integral.h>
#include <__charconv/to_chars_result.h>		#include <__charconv/to_chars_result.h>
		#include <__charconv/traits.h>
#include <__config>		#include <__config>
#include <__debug>		#include <__debug>
#include <__errc>		#include <__errc>
#include <__memory/addressof.h>
#include <__type_traits/is_unsigned.h>
#include <__type_traits/make_32_64_or_128_bit.h>
#include <__type_traits/make_unsigned.h>
#include <__utility/unreachable.h>
#include <cmath> // for log2f		#include <cmath> // for log2f
#include <cstdint>		#include <cstdint>
#include <cstdlib>		#include <cstdlib>
#include <limits>		#include <limits>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)		#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header		# pragma GCC system_header
#endif		#endif

_LIBCPP_PUSH_MACROS
#include <__undef_macros>

_LIBCPP_BEGIN_NAMESPACE_STD		_LIBCPP_BEGIN_NAMESPACE_STD

#if _LIBCPP_STD_VER >= 17

to_chars_result to_chars(char, char, bool, int = 10) = delete;
from_chars_result from_chars(const char, const char, bool, int = 10) = delete;

namespace __itoa
{

template <typename _Tp, typename = void>
struct _LIBCPP_HIDDEN __traits_base;

template <typename _Tp>
struct _LIBCPP_HIDDEN __traits_base<_Tp, __enable_if_t<sizeof(_Tp) <= sizeof(uint32_t)>>
{
using type = uint32_t;

/// The width estimation using a log10 algorithm.
///
/// The algorithm is based on
/// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10
/// Instead of using IntegerLogBase2 it uses __libcpp_clz. Since that
/// function requires its input to have at least one bit set the value of
/// zero is set to one. This means the first element of the lookup table is
/// zero.
static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI int __width(_Tp __v)
{
auto __t = (32 - std::__libcpp_clz(static_cast<type>(__v \| 1))) * 1233 >> 12;
return __t - (__v < __itoa::__pow10_32[__t]) + 1;
}

static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI char* __convert(char* __p, _Tp __v)
{
return __itoa::__base_10_u32(__p, __v);
}

static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI decltype(__pow10_32)& __pow() { return __itoa::__pow10_32; }
};

template <typename _Tp>
struct _LIBCPP_HIDDEN
__traits_base<_Tp, __enable_if_t<sizeof(_Tp) == sizeof(uint64_t)>> {
using type = uint64_t;

/// The width estimation using a log10 algorithm.
///
/// The algorithm is based on
/// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10
/// Instead of using IntegerLogBase2 it uses __libcpp_clz. Since that
/// function requires its input to have at least one bit set the value of
/// zero is set to one. This means the first element of the lookup table is
/// zero.
static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI int __width(_Tp __v) {
auto __t = (64 - std::__libcpp_clz(static_cast<type>(__v \| 1))) * 1233 >> 12;
return __t - (__v < __itoa::__pow10_64[__t]) + 1;
}

static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI char* __convert(char* __p, _Tp __v) { return __itoa::__base_10_u64(__p, __v); }

static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI decltype(__pow10_64)& __pow() { return __itoa::__pow10_64; }
};


# ifndef _LIBCPP_HAS_NO_INT128
template <typename _Tp>
struct _LIBCPP_HIDDEN
__traits_base<_Tp, __enable_if_t<sizeof(_Tp) == sizeof(__uint128_t)> > {
using type = __uint128_t;

/// The width estimation using a log10 algorithm.
///
/// The algorithm is based on
/// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10
/// Instead of using IntegerLogBase2 it uses __libcpp_clz. Since that
/// function requires its input to have at least one bit set the value of
/// zero is set to one. This means the first element of the lookup table is
/// zero.
static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI int __width(_Tp __v) {
_LIBCPP_ASSERT(__v > numeric_limits<uint64_t>::max(), "The optimizations for this algorithm fail when this isn't true.");
// There's always a bit set in the upper 64-bits.
auto __t = (128 - std::__libcpp_clz(static_cast<uint64_t>(__v >> 64))) * 1233 >> 12;
_LIBCPP_ASSERT(__t >= __itoa::__pow10_128_offset, "Index out of bounds");
// __t is adjusted since the lookup table misses the lower entries.
return __t - (__v < __itoa::__pow10_128[__t - __itoa::__pow10_128_offset]) + 1;
}

static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI char* __convert(char* __p, _Tp __v) { return __itoa::__base_10_u128(__p, __v); }

// TODO FMT This pow function should get an index.
// By moving this to its own header it can be reused by the pow function in to_chars_base_10.
static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI decltype(__pow10_128)& __pow() { return __itoa::__pow10_128; }
};
#endif

template <typename _Tp>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool
__mul_overflowed(unsigned char __a, _Tp __b, unsigned char& __r)
{
auto __c = __a * __b;
__r = __c;
return __c > numeric_limits<unsigned char>::max();
}

template <typename _Tp>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool
__mul_overflowed(unsigned short __a, _Tp __b, unsigned short& __r)
{
auto __c = __a * __b;
__r = __c;
return __c > numeric_limits<unsigned short>::max();
}

template <typename _Tp>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool
__mul_overflowed(_Tp __a, _Tp __b, _Tp& __r)
{
static_assert(is_unsigned<_Tp>::value, "");
return __builtin_mul_overflow(__a, __b, &__r);
}

template <typename _Tp, typename _Up>
inline _LIBCPP_HIDE_FROM_ABI bool
_LIBCPP_CONSTEXPR_SINCE_CXX23 __mul_overflowed(_Tp __a, _Up __b, _Tp& __r)
{
return __itoa::__mul_overflowed(__a, static_cast<_Tp>(__b), __r);
}

template <typename _Tp>
struct _LIBCPP_HIDDEN __traits : __traits_base<_Tp>
{
static constexpr int digits = numeric_limits<_Tp>::digits10 + 1;
using __traits_base<_Tp>::__pow;
using typename __traits_base<_Tp>::type;

// precondition: at least one non-zero character available
static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI char const*
__read(char const* __p, char const* __ep, type& __a, type& __b)
{
type __cprod[digits];
int __j = digits - 1;
int __i = digits;
do
{
if (__p < '0' \|\| __p > '9')
break;
__cprod[--__i] = *__p++ - '0';
} while (__p != __ep && __i != 0);

__a = __inner_product(__cprod + __i + 1, __cprod + __j, __pow() + 1,
__cprod[__i]);
if (__itoa::__mul_overflowed(__cprod[__j], __pow()[__j - __i], __b))
--__p;
return __p;
}

template <typename _It1, typename _It2, class _Up>
static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI _Up
__inner_product(_It1 __first1, _It1 __last1, _It2 __first2, _Up __init)
{
for (; __first1 < __last1; ++__first1, ++__first2)
__init = __init + __first1 *__first2;
return __init;
}
};

} // namespace __itoa

template <typename _Tp>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI _Tp
__complement(_Tp __x)
{
static_assert(is_unsigned<_Tp>::value, "cast to unsigned first");
return _Tp(~__x + 1);
}

template <typename _Tp>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI to_chars_result
__to_chars_itoa(char* __first, char* __last, _Tp __value, false_type);

template <typename _Tp>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI to_chars_result
__to_chars_itoa(char* __first, char* __last, _Tp __value, true_type)
{
auto __x = std::__to_unsigned_like(__value);
if (__value < 0 && __first != __last)
{
*__first++ = '-';
__x = std::__complement(__x);
}

return std::__to_chars_itoa(__first, __last, __x, false_type());
}

template <typename _Tp>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI to_chars_result
__to_chars_itoa(char* __first, char* __last, _Tp __value, false_type)
{
using __tx = __itoa::__traits<_Tp>;
auto __diff = __last - __first;

if (__tx::digits <= __diff \|\| __tx::__width(__value) <= __diff)
return {__tx::__convert(__first, __value), errc(0)};
else
return {__last, errc::value_too_large};
}

# ifndef _LIBCPP_HAS_NO_INT128
template <>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI to_chars_result
__to_chars_itoa(char* __first, char* __last, __uint128_t __value, false_type)
{
// When the value fits in 64-bits use the 64-bit code path. This reduces
// the number of expensive calculations on 128-bit values.
//
// NOTE the 128-bit code path requires this optimization.
if(__value <= numeric_limits<uint64_t>::max())
return __to_chars_itoa(__first, __last, static_cast<uint64_t>(__value), false_type());

using __tx = __itoa::__traits<__uint128_t>;
auto __diff = __last - __first;

if (__tx::digits <= __diff \|\| __tx::__width(__value) <= __diff)
return {__tx::__convert(__first, __value), errc(0)};
else
return {__last, errc::value_too_large};
}
#endif

template <class _Tp>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI to_chars_result
__to_chars_integral(char* __first, char* __last, _Tp __value, int __base, false_type);

template <typename _Tp>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI to_chars_result
__to_chars_integral(char* __first, char* __last, _Tp __value, int __base,
true_type)
{
auto __x = std::__to_unsigned_like(__value);
if (__value < 0 && __first != __last)
{
*__first++ = '-';
__x = std::__complement(__x);
}

return std::__to_chars_integral(__first, __last, __x, __base, false_type());
}

namespace __itoa {

template <unsigned _Base>
struct _LIBCPP_HIDDEN __integral;

template <>
struct _LIBCPP_HIDDEN __integral<2> {
template <typename _Tp>
_LIBCPP_HIDE_FROM_ABI static constexpr int __width(_Tp __value) noexcept {
// If value == 0 still need one digit. If the value != this has no
// effect since the code scans for the most significant bit set. (Note
// that __libcpp_clz doesn't work for 0.)
return numeric_limits<_Tp>::digits - std::__libcpp_clz(__value \| 1);
}

template <typename _Tp>
_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI static to_chars_result __to_chars(char* __first, char* __last, _Tp __value) {
ptrdiff_t __cap = __last - __first;
int __n = __width(__value);
if (__n > __cap)
return {__last, errc::value_too_large};

__last = __first + __n;
char* __p = __last;
const unsigned __divisor = 16;
while (__value > __divisor) {
unsigned __c = __value % __divisor;
__value /= __divisor;
__p -= 4;
std::copy_n(&__base_2_lut[4 * __c], 4, __p);
}
do {
unsigned __c = __value % 2;
__value /= 2;
*--__p = "01"[__c];
} while (__value != 0);
return {__last, errc(0)};
}
};

template <>
struct _LIBCPP_HIDDEN __integral<8> {
template <typename _Tp>
_LIBCPP_HIDE_FROM_ABI static constexpr int __width(_Tp __value) noexcept {
// If value == 0 still need one digit. If the value != this has no
// effect since the code scans for the most significat bit set. (Note
// that __libcpp_clz doesn't work for 0.)
return ((numeric_limits<_Tp>::digits - std::__libcpp_clz(__value \| 1)) + 2) / 3;
}

template <typename _Tp>
_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI static to_chars_result __to_chars(char* __first, char* __last, _Tp __value) {
ptrdiff_t __cap = __last - __first;
int __n = __width(__value);
if (__n > __cap)
return {__last, errc::value_too_large};

__last = __first + __n;
char* __p = __last;
unsigned __divisor = 64;
while (__value > __divisor) {
unsigned __c = __value % __divisor;
__value /= __divisor;
__p -= 2;
std::copy_n(&__base_8_lut[2 * __c], 2, __p);
}
do {
unsigned __c = __value % 8;
__value /= 8;
*--__p = "01234567"[__c];
} while (__value != 0);
return {__last, errc(0)};
}

};

template <>
struct _LIBCPP_HIDDEN __integral<16> {
template <typename _Tp>
_LIBCPP_HIDE_FROM_ABI static constexpr int __width(_Tp __value) noexcept {
// If value == 0 still need one digit. If the value != this has no
// effect since the code scans for the most significat bit set. (Note
// that __libcpp_clz doesn't work for 0.)
return (numeric_limits<_Tp>::digits - std::__libcpp_clz(__value \| 1) + 3) / 4;
}

template <typename _Tp>
_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI static to_chars_result __to_chars(char* __first, char* __last, _Tp __value) {
ptrdiff_t __cap = __last - __first;
int __n = __width(__value);
if (__n > __cap)
return {__last, errc::value_too_large};

__last = __first + __n;
char* __p = __last;
unsigned __divisor = 256;
while (__value > __divisor) {
unsigned __c = __value % __divisor;
__value /= __divisor;
__p -= 2;
std::copy_n(&__base_16_lut[2 * __c], 2, __p);
}
if (__first != __last)
do {
unsigned __c = __value % 16;
__value /= 16;
*--__p = "0123456789abcdef"[__c];
} while (__value != 0);
return {__last, errc(0)};
}
};

} // namespace __itoa

template <unsigned _Base, typename _Tp,
typename enable_if<(sizeof(_Tp) >= sizeof(unsigned)), int>::type = 0>
_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI int
__to_chars_integral_width(_Tp __value) {
return __itoa::__integral<_Base>::__width(__value);
}

template <unsigned _Base, typename _Tp,
typename enable_if<(sizeof(_Tp) < sizeof(unsigned)), int>::type = 0>
_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI int
__to_chars_integral_width(_Tp __value) {
return std::__to_chars_integral_width<_Base>(static_cast<unsigned>(__value));
}

template <unsigned _Base, typename _Tp,
typename enable_if<(sizeof(_Tp) >= sizeof(unsigned)), int>::type = 0>
_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI to_chars_result
__to_chars_integral(char* __first, char* __last, _Tp __value) {
return __itoa::__integral<_Base>::__to_chars(__first, __last, __value);
}

template <unsigned _Base, typename _Tp,
typename enable_if<(sizeof(_Tp) < sizeof(unsigned)), int>::type = 0>
_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI to_chars_result
__to_chars_integral(char* __first, char* __last, _Tp __value) {
return std::__to_chars_integral<_Base>(__first, __last, static_cast<unsigned>(__value));
}

template <typename _Tp>
_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI int
__to_chars_integral_width(_Tp __value, unsigned __base) {
_LIBCPP_ASSERT(__value >= 0, "The function requires a non-negative value.");

unsigned __base_2 = __base * __base;
unsigned __base_3 = __base_2 * __base;
unsigned __base_4 = __base_2 * __base_2;

int __r = 0;
while (true) {
if (__value < __base)
return __r + 1;
if (__value < __base_2)
return __r + 2;
if (__value < __base_3)
return __r + 3;
if (__value < __base_4)
return __r + 4;

__value /= __base_4;
__r += 4;
}

__libcpp_unreachable();
}

template <typename _Tp>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI to_chars_result
__to_chars_integral(char* __first, char* __last, _Tp __value, int __base,
false_type)
{
if (__base == 10) [[likely]]
return std::__to_chars_itoa(__first, __last, __value, false_type());

switch (__base) {
case 2:
return std::__to_chars_integral<2>(__first, __last, __value);
case 8:
return std::__to_chars_integral<8>(__first, __last, __value);
case 16:
return std::__to_chars_integral<16>(__first, __last, __value);
}

ptrdiff_t __cap = __last - __first;
int __n = std::__to_chars_integral_width(__value, __base);
if (__n > __cap)
return {__last, errc::value_too_large};

__last = __first + __n;
char* __p = __last;
do {
unsigned __c = __value % __base;
__value /= __base;
*--__p = "0123456789abcdefghijklmnopqrstuvwxyz"[__c];
} while (__value != 0);
return {__last, errc(0)};
}

template <typename _Tp, typename enable_if<is_integral<_Tp>::value, int>::type = 0>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI to_chars_result
to_chars(char* __first, char* __last, _Tp __value)
{
using _Type = __make_32_64_or_128_bit_t<_Tp>;
static_assert(!is_same<_Type, void>::value, "unsupported integral type used in to_chars");
return std::__to_chars_itoa(__first, __last, static_cast<_Type>(__value), is_signed<_Tp>());
}

template <typename _Tp, typename enable_if<is_integral<_Tp>::value, int>::type = 0>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI to_chars_result
to_chars(char* __first, char* __last, _Tp __value, int __base)
{
_LIBCPP_ASSERT(2 <= __base && __base <= 36, "base not in [2, 36]");

using _Type = __make_32_64_or_128_bit_t<_Tp>;
return std::__to_chars_integral(__first, __last, static_cast<_Type>(__value), __base, is_signed<_Tp>());
}

template <typename _It, typename _Tp, typename _Fn, typename... _Ts>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI from_chars_result
__sign_combinator(_It __first, _It __last, _Tp& __value, _Fn __f, _Ts... __args)
{
using __tl = numeric_limits<_Tp>;
decltype(std::__to_unsigned_like(__value)) __x;

bool __neg = (__first != __last && *__first == '-');
auto __r = __f(__neg ? __first + 1 : __first, __last, __x, __args...);
switch (__r.ec)
{
case errc::invalid_argument:
return {__first, __r.ec};
case errc::result_out_of_range:
return __r;
default:
break;
}

if (__neg)
{
if (__x <= std::__complement(std::__to_unsigned_like(__tl::min())))
{
__x = std::__complement(__x);
std::copy_n(std::addressof(__x), 1, std::addressof(__value));
return __r;
}
}
else
{
if (__x <= std::__to_unsigned_like(__tl::max()))
{
__value = __x;
return __r;
}
}

return {__r.ptr, errc::result_out_of_range};
}

template <typename _Tp>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool
__in_pattern(_Tp __c)
{
return '0' <= __c && __c <= '9';
}

struct _LIBCPP_HIDDEN __in_pattern_result
{
bool __ok;
int __val;

explicit _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI operator bool() const { return __ok; }
};

template <typename _Tp>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI __in_pattern_result
__in_pattern(_Tp __c, int __base)
{
if (__base <= 10)
return {'0' <= __c && __c < '0' + __base, __c - '0'};
else if (std::__in_pattern(__c))
return {true, __c - '0'};
else if ('a' <= __c && __c < 'a' + __base - 10)
return {true, __c - 'a' + 10};
else
return {'A' <= __c && __c < 'A' + __base - 10, __c - 'A' + 10};
}

template <typename _It, typename _Tp, typename _Fn, typename... _Ts>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI from_chars_result
__subject_seq_combinator(_It __first, _It __last, _Tp& __value, _Fn __f,
_Ts... __args)
{
auto __find_non_zero = [](_It __firstit, _It __lastit) {
for (; __firstit != __lastit; ++__firstit)
if (*__firstit != '0')
break;
return __firstit;
};

auto __p = __find_non_zero(__first, __last);
if (__p == __last \|\| !std::__in_pattern(*__p, __args...))
{
if (__p == __first)
return {__first, errc::invalid_argument};
else
{
__value = 0;
return {__p, {}};
}
}

auto __r = __f(__p, __last, __value, __args...);
if (__r.ec == errc::result_out_of_range)
{
for (; __r.ptr != __last; ++__r.ptr)
{
if (!std::__in_pattern(*__r.ptr, __args...))
break;
}
}

return __r;
}

template <typename _Tp, typename enable_if<is_unsigned<_Tp>::value, int>::type = 0>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI from_chars_result
__from_chars_atoi(const char* __first, const char* __last, _Tp& __value)
{
using __tx = __itoa::__traits<_Tp>;
using __output_type = typename __tx::type;

return std::__subject_seq_combinator(
__first, __last, __value,
[](const char* __f, const char* __l,
_Tp& __val) -> from_chars_result {
__output_type __a, __b;
auto __p = __tx::__read(__f, __l, __a, __b);
if (__p == __l \|\| !std::__in_pattern(*__p))
{
__output_type __m = numeric_limits<_Tp>::max();
if (__m >= __a && __m - __a >= __b)
{
__val = __a + __b;
return {__p, {}};
}
}
return {__p, errc::result_out_of_range};
});
}

template <typename _Tp, typename enable_if<is_signed<_Tp>::value, int>::type = 0>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI from_chars_result
__from_chars_atoi(const char* __first, const char* __last, _Tp& __value)
{
using __t = decltype(std::__to_unsigned_like(__value));
return std::__sign_combinator(__first, __last, __value, __from_chars_atoi<__t>);
}


/*
// Code used to generate __from_chars_log2f_lut.
#include <cmath>
#include <iostream>
#include <format>

int main() {
for (int i = 2; i <= 36; ++i)
std::cout << std::format("{},\n", log2f(i));
}
*/
/// log2f table for bases [2, 36].
inline constexpr float __from_chars_log2f_lut[35] = {
1, 1.5849625, 2, 2.321928, 2.5849626, 2.807355, 3, 3.169925, 3.321928,
3.4594316, 3.5849626, 3.7004397, 3.807355, 3.9068906, 4, 4.087463, 4.169925, 4.2479277,
4.321928, 4.3923173, 4.4594316, 4.523562, 4.5849624, 4.643856, 4.70044, 4.7548876, 4.807355,
4.857981, 4.9068904, 4.9541965, 5, 5.044394, 5.087463, 5.129283, 5.169925};

template <typename _Tp, typename enable_if<is_unsigned<_Tp>::value, int>::type = 0>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI from_chars_result
__from_chars_integral(const char* __first, const char* __last, _Tp& __value,
int __base)
{
if (__base == 10)
return std::__from_chars_atoi(__first, __last, __value);

return std::__subject_seq_combinator(
__first, __last, __value,
[](const char* __p, const char* __lastp, _Tp& __val,
int __b) -> from_chars_result {
using __tl = numeric_limits<_Tp>;
// __base is always between 2 and 36 inclusive.
auto __digits = __tl::digits / __from_chars_log2f_lut[__b - 2];
_Tp __x = __in_pattern(*__p++, __b).__val, __y = 0;

for (int __i = 1; __p != __lastp; ++__i, ++__p)
{
if (auto __c = __in_pattern(*__p, __b))
{
if (__i < __digits - 1)
__x = __x * __b + __c.__val;
else
{
if (!__itoa::__mul_overflowed(__x, __b, __x))
++__p;
__y = __c.__val;
break;
}
}
else
break;
}

if (__p == __lastp \|\| !__in_pattern(*__p, __b))
{
if (__tl::max() - __x >= __y)
{
__val = __x + __y;
return {__p, {}};
}
}
return {__p, errc::result_out_of_range};
},
__base);
}

template <typename _Tp, typename enable_if<is_signed<_Tp>::value, int>::type = 0>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI from_chars_result
__from_chars_integral(const char* __first, const char* __last, _Tp& __value,
int __base)
{
using __t = decltype(std::__to_unsigned_like(__value));
return std::__sign_combinator(__first, __last, __value,
__from_chars_integral<__t>, __base);
}

template <typename _Tp, typename enable_if<is_integral<_Tp>::value, int>::type = 0>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI from_chars_result
from_chars(const char* __first, const char* __last, _Tp& __value)
{
return std::__from_chars_atoi(__first, __last, __value);
}

template <typename _Tp, typename enable_if<is_integral<_Tp>::value, int>::type = 0>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI from_chars_result
from_chars(const char* __first, const char* __last, _Tp& __value, int __base)
{
_LIBCPP_ASSERT(2 <= __base && __base <= 36, "base not in [2, 36]");
return std::__from_chars_integral(__first, __last, __value, __base);
}

_LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT _LIBCPP_FUNC_VIS
to_chars_result to_chars(char* __first, char* __last, float __value);

_LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT _LIBCPP_FUNC_VIS
to_chars_result to_chars(char* __first, char* __last, double __value);

_LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT _LIBCPP_FUNC_VIS
to_chars_result to_chars(char* __first, char* __last, long double __value);

_LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT _LIBCPP_FUNC_VIS
to_chars_result to_chars(char* __first, char* __last, float __value, chars_format __fmt);

_LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT _LIBCPP_FUNC_VIS
to_chars_result to_chars(char* __first, char* __last, double __value, chars_format __fmt);

_LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT _LIBCPP_FUNC_VIS
to_chars_result to_chars(char* __first, char* __last, long double __value, chars_format __fmt);

_LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT _LIBCPP_FUNC_VIS
to_chars_result to_chars(char* __first, char* __last, float __value, chars_format __fmt, int __precision);

_LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT _LIBCPP_FUNC_VIS
to_chars_result to_chars(char* __first, char* __last, double __value, chars_format __fmt, int __precision);

_LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT _LIBCPP_FUNC_VIS
to_chars_result to_chars(char* __first, char* __last, long double __value, chars_format __fmt, int __precision);

#endif // _LIBCPP_STD_VER >= 17

_LIBCPP_END_NAMESPACE_STD		_LIBCPP_END_NAMESPACE_STD

_LIBCPP_POP_MACROS

#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20		#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
# include <concepts>		# include <concepts>
# include <cstring>		# include <cstring>
# include <iosfwd>		# include <iosfwd>
# include <type_traits>		# include <type_traits>
#endif		#endif

#endif // _LIBCPP_CHARCONV		#endif // _LIBCPP_CHARCONV