86 lines
2.7 KiB
C++
86 lines
2.7 KiB
C++
// Copyright (c) 2022 Dvir Yitzchaki.
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// Use, modification and distribution are subject to the Boost Software License,
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// Version 1.0. See http://www.boost.org/LICENSE_1_0.txt.
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#ifndef BOOST_CONVERT_CHARCONV_BASED_CONVERTER_HPP
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#define BOOST_CONVERT_CHARCONV_BASED_CONVERTER_HPP
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#ifdef BOOST_NO_CXX17_HDR_CHARCONV
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#error "This header requires <charconv> which is unavailable"
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#endif // BOOST_NO_CXX17_HDR_CHARCONV
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#ifdef BOOST_NO_CXX17_STRUCTURED_BINDINGS
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#error "This header requires structured bindings which is unavailable"
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#endif // BOOST_NO_CXX17_STRUCTURED_BINDINGS
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#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
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#error "This header requires constexpr if which is unavailable"
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#endif // BOOST_NO_CXX17_IF_CONSTEXPR
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#include <boost/convert/base.hpp>
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#include <charconv>
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#include <type_traits>
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namespace boost::cnv { struct charconv; }
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/// @brief std::to/from_chars-based extended converter
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/// @details The converter offers good overall performance and moderate formatting facilities.
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struct boost::cnv::charconv : boost::cnv::cnvbase<boost::cnv::charconv>
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{
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using this_type = boost::cnv::charconv;
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using base_type = boost::cnv::cnvbase<this_type>;
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private:
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friend struct boost::cnv::cnvbase<this_type>;
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template<typename in_type>
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cnv::range<char*>
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to_str(in_type value_in, char* buf) const
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{
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const auto [ptr, ec] = [&]{
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if constexpr (std::is_integral_v<in_type>) {
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return std::to_chars(buf, buf + bufsize_, value_in, static_cast<int>(base_));
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} else {
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return std::to_chars(buf, buf + bufsize_, value_in, chars_format(), precision_);
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}
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}();
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bool success = ec == std::errc{};
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return cnv::range<char*>(buf, success ? ptr : buf);
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}
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template<typename string_type, typename out_type>
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void
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str_to(cnv::range<string_type> range, optional<out_type>& result_out) const
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{
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out_type result = boost::make_default<out_type>();
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const auto [ptr, ec] = [&]{
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if constexpr (std::is_integral_v<out_type>) {
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return std::from_chars(&*range.begin(), &*range.end(), result, static_cast<int>(base_));
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} else {
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return std::from_chars(&*range.begin(), &*range.end(), result, chars_format());
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}
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}();
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if (ec == std::errc{})
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result_out = result;
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}
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std::chars_format chars_format() const
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{
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static constexpr std::chars_format format[] =
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{
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std::chars_format::fixed,
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std::chars_format::scientific,
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std::chars_format::hex
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};
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return format[int(notation_)];
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}
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std::chars_format fmt_ = std::chars_format::fixed;
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};
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#endif // BOOST_CONVERT_CHARCONV_BASED_CONVERTER_HPP
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