chromium/third_party/fast_float/src/include/fast_float/parse_number.h

#ifndef FASTFLOAT_PARSE_NUMBER_H
#define FASTFLOAT_PARSE_NUMBER_H

#include "ascii_number.h"
#include "decimal_to_binary.h"
#include "digit_comparison.h"
#include "float_common.h"

#include <cmath>
#include <cstring>
#include <limits>
#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, typename UC>
from_chars_result_t<UC> FASTFLOAT_CONSTEXPR14 parse_infnan(UC const *first,
                                                           UC const *last,
                                                           T &value) noexcept { … }

/**
 * Returns true if the floating-pointing rounding mode is to 'nearest'.
 * It is the default on most system. This function is meant to be inexpensive.
 * Credit : @mwalcott3
 */
fastfloat_really_inline bool rounds_to_nearest() noexcept { … }

} // namespace detail

template <typename T> struct from_chars_caller { … };

#if __STDCPP_FLOAT32_T__ == 1
template <> struct from_chars_caller<std::float32_t> {
  template <typename UC>
  FASTFLOAT_CONSTEXPR20 static from_chars_result_t<UC>
  call(UC const *first, UC const *last, std::float32_t &value,
       parse_options_t<UC> options) noexcept {
    // if std::float32_t is defined, and we are in C++23 mode; macro set for
    // float32; set value to float due to equivalence between float and
    // float32_t
    float val;
    auto ret = from_chars_advanced(first, last, val, options);
    value = val;
    return ret;
  }
};
#endif

#if __STDCPP_FLOAT64_T__ == 1
template <> struct from_chars_caller<std::float64_t> {
  template <typename UC>
  FASTFLOAT_CONSTEXPR20 static from_chars_result_t<UC>
  call(UC const *first, UC const *last, std::float64_t &value,
       parse_options_t<UC> options) noexcept {
    // if std::float64_t is defined, and we are in C++23 mode; macro set for
    // float64; set value as double due to equivalence between double and
    // float64_t
    double val;
    auto ret = from_chars_advanced(first, last, val, options);
    value = val;
    return ret;
  }
};
#endif

template <typename T, typename UC, typename>
FASTFLOAT_CONSTEXPR20 from_chars_result_t<UC>
from_chars(UC const *first, UC const *last, T &value,
           chars_format fmt /*= chars_format::general*/) noexcept { … }

/**
 * This function overload takes parsed_number_string_t structure that is created
 * and populated either by from_chars_advanced function taking chars range and
 * parsing options or other parsing custom function implemented by user.
 */
template <typename T, typename UC>
FASTFLOAT_CONSTEXPR20 from_chars_result_t<UC>
from_chars_advanced(parsed_number_string_t<UC> &pns, T &value) noexcept { … }

template <typename T, typename UC>
FASTFLOAT_CONSTEXPR20 from_chars_result_t<UC>
from_chars_advanced(UC const *first, UC const *last, T &value,
                    parse_options_t<UC> options) noexcept { … }

template <typename T, typename UC, typename>
FASTFLOAT_CONSTEXPR20 from_chars_result_t<UC>
from_chars(UC const *first, UC const *last, T &value, int base) noexcept { … }

} // namespace fast_float

#endif