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// Copyright Kevlin Henney, 2000-2005.
// Copyright Alexander Nasonov, 2006-2010.
// Copyright Antony Polukhin, 2011-2014.
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// what: lexical_cast custom keyword cast
// who: contributed by Kevlin Henney,
// enhanced with contributions from Terje Slettebo,
// with additional fixes and suggestions from Gennaro Prota,
// Beman Dawes, Dave Abrahams, Daryle Walker, Peter Dimov,
// Alexander Nasonov, Antony Polukhin, Justin Viiret, Michael Hofmann,
// Cheng Yang, Matthew Bradbury, David W. Birdsall, Pavel Korzh and other Boosters
// when: November 2000, March 2003, June 2005, June 2006, March 2011 - 2014
#ifndef BOOST_LEXICAL_CAST_TRY_LEXICAL_CONVERT_HPP
#define BOOST_LEXICAL_CAST_TRY_LEXICAL_CONVERT_HPP
#include <boost/config.hpp>
#ifdef BOOST_HAS_PRAGMA_ONCE
# pragma once
#endif
#include <string>
#include <boost/mpl/if.hpp>
#include <boost/type_traits/ice.hpp>
#include <boost/type_traits/is_same.hpp>
#include <boost/type_traits/is_arithmetic.hpp>
#include <boost/lexical_cast/detail/is_character.hpp>
#include <boost/lexical_cast/detail/converter_numeric.hpp>
#include <boost/lexical_cast/detail/converter_lexical.hpp>
#include <boost/range/iterator_range_core.hpp>
#include <boost/container/container_fwd.hpp>
namespace boost {
namespace detail
{
template<typename T>
struct is_stdstring
: boost::false_type
{};
template<typename CharT, typename Traits, typename Alloc>
struct is_stdstring< std::basic_string<CharT, Traits, Alloc> >
: boost::true_type
{};
template<typename CharT, typename Traits, typename Alloc>
struct is_stdstring< boost::container::basic_string<CharT, Traits, Alloc> >
: boost::true_type
{};
template<typename Target, typename Source>
struct is_arithmetic_and_not_xchars
{
BOOST_STATIC_CONSTANT(bool, value = (
boost::type_traits::ice_and<
boost::type_traits::ice_not<
boost::detail::is_character<Target>::value
>::value,
boost::type_traits::ice_not<
boost::detail::is_character<Source>::value
>::value,
boost::is_arithmetic<Source>::value,
boost::is_arithmetic<Target>::value
>::value
));
};
/*
* is_xchar_to_xchar<Target, Source>::value is true,
* Target and Souce are char types of the same size 1 (char, signed char, unsigned char).
*/
template<typename Target, typename Source>
struct is_xchar_to_xchar
{
BOOST_STATIC_CONSTANT(bool, value = (
boost::type_traits::ice_and<
boost::type_traits::ice_eq<sizeof(Source), sizeof(Target)>::value,
boost::type_traits::ice_eq<sizeof(Source), sizeof(char)>::value,
boost::detail::is_character<Target>::value,
boost::detail::is_character<Source>::value
>::value
));
};
template<typename Target, typename Source>
struct is_char_array_to_stdstring
: boost::false_type
{};
template<typename CharT, typename Traits, typename Alloc>
struct is_char_array_to_stdstring< std::basic_string<CharT, Traits, Alloc>, CharT* >
: boost::true_type
{};
template<typename CharT, typename Traits, typename Alloc>
struct is_char_array_to_stdstring< std::basic_string<CharT, Traits, Alloc>, const CharT* >
: boost::true_type
{};
template<typename CharT, typename Traits, typename Alloc>
struct is_char_array_to_stdstring< boost::container::basic_string<CharT, Traits, Alloc>, CharT* >
: boost::true_type
{};
template<typename CharT, typename Traits, typename Alloc>
struct is_char_array_to_stdstring< boost::container::basic_string<CharT, Traits, Alloc>, const CharT* >
: boost::true_type
{};
template <typename Target, typename Source>
struct copy_converter_impl
{
// MSVC fail to forward an array (DevDiv#555157 "SILENT BAD CODEGEN triggered by perfect forwarding",
// fixed in 2013 RTM).
#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && (!defined(BOOST_MSVC) || BOOST_MSVC >= 1800)
template <class T>
static inline bool try_convert(T&& arg, Target& result) {
result = static_cast<T&&>(arg); // eqaul to `result = std::forward<T>(arg);`
return true;
}
#else
static inline bool try_convert(const Source& arg, Target& result) {
result = arg;
return true;
}
#endif
};
}
namespace conversion { namespace detail {
template <typename Target, typename Source>
inline bool try_lexical_convert(const Source& arg, Target& result)
{
typedef BOOST_DEDUCED_TYPENAME boost::detail::array_to_pointer_decay<Source>::type src;
typedef BOOST_DEDUCED_TYPENAME boost::type_traits::ice_or<
boost::detail::is_xchar_to_xchar<Target, src >::value,
boost::detail::is_char_array_to_stdstring<Target, src >::value,
boost::type_traits::ice_and<
boost::is_same<Target, src >::value,
boost::detail::is_stdstring<Target >::value
>::value,
boost::type_traits::ice_and<
boost::is_same<Target, src >::value,
boost::detail::is_character<Target >::value
>::value
> shall_we_copy_t;
typedef boost::detail::is_arithmetic_and_not_xchars<Target, src >
shall_we_copy_with_dynamic_check_t;
// We do evaluate second `if_` lazily to avoid unnecessary instantiations
// of `shall_we_copy_with_dynamic_check_t` and improve compilation times.
typedef BOOST_DEDUCED_TYPENAME boost::mpl::if_c<
shall_we_copy_t::value,
boost::mpl::identity<boost::detail::copy_converter_impl<Target, src > >,
boost::mpl::if_<
shall_we_copy_with_dynamic_check_t,
boost::detail::dynamic_num_converter_impl<Target, src >,
boost::detail::lexical_converter_impl<Target, src >
>
>::type caster_type_lazy;
typedef BOOST_DEDUCED_TYPENAME caster_type_lazy::type caster_type;
return caster_type::try_convert(arg, result);
}
template <typename Target, typename CharacterT>
inline bool try_lexical_convert(const CharacterT* chars, std::size_t count, Target& result)
{
BOOST_STATIC_ASSERT_MSG(
boost::detail::is_character<CharacterT>::value,
"This overload of try_lexical_convert is meant to be used only with arrays of characters."
);
return ::boost::conversion::detail::try_lexical_convert(
::boost::iterator_range<const CharacterT*>(chars, chars + count), result
);
}
}} // namespace conversion::detail
namespace conversion {
// ADL barrier
using ::boost::conversion::detail::try_lexical_convert;
}
} // namespace boost
#endif // BOOST_LEXICAL_CAST_TRY_LEXICAL_CONVERT_HPP
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