detail/fast_float/fast_float.hpp

0001 // Copyright 2020-2023 Daniel Lemire
0002 // Copyright 2023 Matt Borland
0003 // Distributed under the Boost Software License, Version 1.0.
0004 // https://www.boost.org/LICENSE_1_0.txt
0005 //
0006 // Derivative of: https://github.com/fastfloat/fast_float
0007
0008 #ifndef BOOST_CHARCONV_DETAIL_FASTFLOAT_FAST_FLOAT_HPP
0009 #define BOOST_CHARCONV_DETAIL_FASTFLOAT_FAST_FLOAT_HPP
0010
0011 #include <boost/charconv/detail/fast_float/float_common.hpp>
0012
0013 namespace boost { namespace charconv { namespace detail { namespace fast_float {
0014 /**
0015  * This function parses the character sequence [first,last) for a number. It parses floating-point numbers expecting
0016  * a locale-independent format equivalent to what is used by std::strtod in the default ("C") locale.
0017  * The resulting floating-point value is the closest floating-point values (using either float or double),
0018  * using the "round to even" convention for values that would otherwise fall right in-between two values.
0019  * That is, we provide exact parsing according to the IEEE standard.
0020  *
0021  * Given a successful parse, the pointer (`ptr`) in the returned value is set to point right after the
0022  * parsed number, and the `value` referenced is set to the parsed value. In case of error, the returned
0023  * `ec` contains a representative error, otherwise the default (`std::errc()`) value is stored.
0024  *
0025  * The implementation does not throw and does not allocate memory (e.g., with `new` or `malloc`).
0026  *
0027  * Like the C++17 standard, the `fast_float::from_chars` functions take an optional last argument of
0028  * the type `fast_float::chars_format`. It is a bitset value: we check whether
0029  * `fmt & fast_float::chars_format::fixed` and `fmt & fast_float::chars_format::scientific` are set
0030  * to determine whether we allow the fixed point and scientific notation respectively.
0031  * The default is  `fast_float::chars_format::general` which allows both `fixed` and `scientific`.
0032  */
0033 template<typename T, typename UC = char>
0034 BOOST_CHARCONV_FASTFLOAT_CONSTEXPR20
0035 from_chars_result_t<UC> from_chars(UC const * first, UC const * last,
0036                              T &value, chars_format fmt = chars_format::general)  noexcept;
0037
0038 /**
0039  * Like from_chars, but accepts an `options` argument to govern number parsing.
0040  */
0041 template<typename T, typename UC = char>
0042 BOOST_CHARCONV_FASTFLOAT_CONSTEXPR20
0043 from_chars_result_t<UC> from_chars_advanced(UC const * first, UC const * last,
0044                                       T &value, parse_options_t<UC> options)  noexcept;
0045
0046 }}}} // namespace fast_float
0047 #include <boost/charconv/detail/fast_float/parse_number.hpp>
0048 #endif // BOOST_CHARCONV_FASTFLOAT_FAST_FLOAT_H