176 lines
5.0 KiB
C++
176 lines
5.0 KiB
C++
// Copyright Kevlin Henney, 2000-2005.
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// Copyright Alexander Nasonov, 2006-2010.
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// Copyright Antony Polukhin, 2011-2022.
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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// what: lexical_cast custom keyword cast
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// who: contributed by Kevlin Henney,
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// enhanced with contributions from Terje Slettebo,
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// with additional fixes and suggestions from Gennaro Prota,
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// Beman Dawes, Dave Abrahams, Daryle Walker, Peter Dimov,
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// Alexander Nasonov, Antony Polukhin, Justin Viiret, Michael Hofmann,
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// Cheng Yang, Matthew Bradbury, David W. Birdsall, Pavel Korzh and other Boosters
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// when: November 2000, March 2003, June 2005, June 2006, March 2011 - 2014
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#ifndef BOOST_LEXICAL_CAST_LEXICAL_CAST_OLD_HPP
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#define BOOST_LEXICAL_CAST_LEXICAL_CAST_OLD_HPP
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#include <boost/config.hpp>
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#ifdef BOOST_HAS_PRAGMA_ONCE
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# pragma once
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#endif
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#if defined(BOOST_NO_STRINGSTREAM) || defined(BOOST_NO_STD_WSTRING)
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#define BOOST_LCAST_NO_WCHAR_T
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#endif
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#include <climits>
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#include <cstddef>
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#include <string>
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#include <cstring>
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#include <cstdio>
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#include <boost/limits.hpp>
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#include <boost/type_traits/is_pointer.hpp>
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#include <boost/static_assert.hpp>
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#include <boost/detail/lcast_precision.hpp>
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#include <boost/detail/workaround.hpp>
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#ifdef BOOST_NO_STRINGSTREAM
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#include <strstream>
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#else
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#include <sstream>
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#endif
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#include <boost/lexical_cast/bad_lexical_cast.hpp>
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#include <boost/lexical_cast/detail/widest_char.hpp>
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namespace boost {
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namespace detail
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{
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// selectors for choosing stream character type
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template<typename Type>
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struct stream_char
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{
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typedef char type;
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};
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#ifndef BOOST_LCAST_NO_WCHAR_T
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#ifndef BOOST_NO_INTRINSIC_WCHAR_T
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template<>
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struct stream_char<wchar_t>
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{
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typedef wchar_t type;
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};
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#endif
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template<>
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struct stream_char<wchar_t *>
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{
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typedef wchar_t type;
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};
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template<>
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struct stream_char<const wchar_t *>
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{
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typedef wchar_t type;
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};
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template<>
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struct stream_char<std::wstring>
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{
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typedef wchar_t type;
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};
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#endif
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// stream wrapper for handling lexical conversions
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template<typename Target, typename Source, typename Traits>
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class lexical_stream
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{
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private:
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typedef typename widest_char<
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typename stream_char<Target>::type,
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typename stream_char<Source>::type>::type char_type;
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typedef Traits traits_type;
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public:
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lexical_stream(char_type* = 0, char_type* = 0)
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{
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stream.unsetf(std::ios::skipws);
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lcast_set_precision(stream, static_cast<Source*>(0), static_cast<Target*>(0) );
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}
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~lexical_stream()
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{
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#if defined(BOOST_NO_STRINGSTREAM)
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stream.freeze(false);
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#endif
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}
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bool operator<<(const Source &input)
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{
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return !(stream << input).fail();
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}
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template<typename InputStreamable>
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bool operator>>(InputStreamable &output)
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{
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return !is_pointer<InputStreamable>::value &&
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stream >> output &&
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stream.get() == traits_type::eof();
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}
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bool operator>>(std::string &output)
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{
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#if defined(BOOST_NO_STRINGSTREAM)
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stream << '\0';
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#endif
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stream.str().swap(output);
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return true;
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}
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#ifndef BOOST_LCAST_NO_WCHAR_T
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bool operator>>(std::wstring &output)
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{
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stream.str().swap(output);
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return true;
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}
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#endif
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private:
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#if defined(BOOST_NO_STRINGSTREAM)
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std::strstream stream;
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#elif defined(BOOST_NO_STD_LOCALE)
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std::stringstream stream;
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#else
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std::basic_stringstream<char_type,traits_type> stream;
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#endif
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};
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}
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// call-by-value fallback version (deprecated)
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template<typename Target, typename Source>
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Target lexical_cast(Source arg)
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{
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typedef typename detail::widest_char<
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BOOST_DEDUCED_TYPENAME detail::stream_char<Target>::type
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, BOOST_DEDUCED_TYPENAME detail::stream_char<Source>::type
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>::type char_type;
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typedef std::char_traits<char_type> traits;
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detail::lexical_stream<Target, Source, traits> interpreter;
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Target result;
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if(!(interpreter << arg && interpreter >> result))
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boost::conversion::detail::throw_bad_cast<Source, Target>();
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return result;
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}
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} // namespace boost
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#undef BOOST_LCAST_NO_WCHAR_T
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#endif // BOOST_LEXICAL_CAST_LEXICAL_CAST_OLD_HPP
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