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https://github.com/fastfloat/fast_float.git
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79 lines
2.8 KiB
C++
79 lines
2.8 KiB
C++
#ifndef FASTFLOAT_FAST_FLOAT_H
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#define FASTFLOAT_FAST_FLOAT_H
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#include <system_error>
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#if !defined(CXX20_CONSTEXPR)
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#define CXX20_CONSTEXPR
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#if defined __has_include
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#if __has_include(<version>)
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#include <version>
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#if defined(__cpp_lib_bit_cast)
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#undef CXX20_CONSTEXPR
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#define CXX20_CONSTEXPR constexpr
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#define HAS_CXX20_CONSTEXPR 1
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#endif
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#endif
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#endif
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#endif
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namespace fast_float {
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enum chars_format {
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scientific = 1<<0,
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fixed = 1<<2,
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hex = 1<<3,
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general = fixed | scientific
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};
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struct from_chars_result {
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const char *ptr;
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std::errc ec;
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};
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struct parse_options {
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constexpr explicit parse_options(chars_format fmt = chars_format::general,
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char dot = '.')
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: format(fmt), decimal_point(dot) {}
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/** Which number formats are accepted */
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chars_format format;
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/** The character used as decimal point */
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char decimal_point;
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};
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/**
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* This function parses the character sequence [first,last) for a number. It parses floating-point numbers expecting
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* a locale-indepent format equivalent to what is used by std::strtod in the default ("C") locale.
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* The resulting floating-point value is the closest floating-point values (using either float or double),
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* using the "round to even" convention for values that would otherwise fall right in-between two values.
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* That is, we provide exact parsing according to the IEEE standard.
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*
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* Given a successful parse, the pointer (`ptr`) in the returned value is set to point right after the
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* parsed number, and the `value` referenced is set to the parsed value. In case of error, the returned
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* `ec` contains a representative error, otherwise the default (`std::errc()`) value is stored.
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*
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* The implementation does not throw and does not allocate memory (e.g., with `new` or `malloc`).
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*
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* Like the C++17 standard, the `fast_float::from_chars` functions take an optional last argument of
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* the type `fast_float::chars_format`. It is a bitset value: we check whether
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* `fmt & fast_float::chars_format::fixed` and `fmt & fast_float::chars_format::scientific` are set
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* to determine whether we allowe the fixed point and scientific notation respectively.
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* The default is `fast_float::chars_format::general` which allows both `fixed` and `scientific`.
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*/
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template<typename T>
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CXX20_CONSTEXPR from_chars_result from_chars(const char *first, const char *last,
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T &value, chars_format fmt = chars_format::general) noexcept;
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/**
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* Like from_chars, but accepts an `options` argument to govern number parsing.
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*/
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template<typename T>
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CXX20_CONSTEXPR from_chars_result from_chars_advanced(const char *first, const char *last,
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T &value, parse_options options) noexcept;
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}
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#include "parse_number.h"
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#endif // FASTFLOAT_FAST_FLOAT_H
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