Chris@102: // Copyright Kevlin Henney, 2000-2005.
Chris@102: // Copyright Alexander Nasonov, 2006-2010.
Chris@102: // Copyright Antony Polukhin, 2011-2014.
Chris@102: //
Chris@102: // Distributed under the Boost Software License, Version 1.0. (See
Chris@102: // accompanying file LICENSE_1_0.txt or copy at
Chris@102: // http://www.boost.org/LICENSE_1_0.txt)
Chris@102: //
Chris@102: // what:  lexical_cast custom keyword cast
Chris@102: // who:   contributed by Kevlin Henney,
Chris@102: //        enhanced with contributions from Terje Slettebo,
Chris@102: //        with additional fixes and suggestions from Gennaro Prota,
Chris@102: //        Beman Dawes, Dave Abrahams, Daryle Walker, Peter Dimov,
Chris@102: //        Alexander Nasonov, Antony Polukhin, Justin Viiret, Michael Hofmann,
Chris@102: //        Cheng Yang, Matthew Bradbury, David W. Birdsall, Pavel Korzh and other Boosters
Chris@102: // when:  November 2000, March 2003, June 2005, June 2006, March 2011 - 2014
Chris@102: 
Chris@102: #ifndef BOOST_LEXICAL_CAST_TRY_LEXICAL_CONVERT_HPP
Chris@102: #define BOOST_LEXICAL_CAST_TRY_LEXICAL_CONVERT_HPP
Chris@102: 
Chris@102: #include <boost/config.hpp>
Chris@102: #ifdef BOOST_HAS_PRAGMA_ONCE
Chris@102: #   pragma once
Chris@102: #endif
Chris@102: 
Chris@102: #include <string>
Chris@102: #include <boost/mpl/if.hpp>
Chris@102: #include <boost/type_traits/ice.hpp>
Chris@102: #include <boost/type_traits/is_same.hpp>
Chris@102: #include <boost/type_traits/is_arithmetic.hpp>
Chris@102: 
Chris@102: #include <boost/lexical_cast/detail/is_character.hpp>
Chris@102: #include <boost/lexical_cast/detail/converter_numeric.hpp>
Chris@102: #include <boost/lexical_cast/detail/converter_lexical.hpp>
Chris@102: 
Chris@102: #include <boost/range/iterator_range_core.hpp>
Chris@102: #include <boost/container/container_fwd.hpp>
Chris@102: 
Chris@102: namespace boost {
Chris@102:     namespace detail
Chris@102:     {
Chris@102:         template<typename T>
Chris@102:         struct is_stdstring
Chris@102:             : boost::false_type
Chris@102:         {};
Chris@102: 
Chris@102:         template<typename CharT, typename Traits, typename Alloc>
Chris@102:         struct is_stdstring< std::basic_string<CharT, Traits, Alloc> >
Chris@102:             : boost::true_type
Chris@102:         {};
Chris@102: 
Chris@102:         template<typename CharT, typename Traits, typename Alloc>
Chris@102:         struct is_stdstring< boost::container::basic_string<CharT, Traits, Alloc> >
Chris@102:             : boost::true_type
Chris@102:         {};
Chris@102: 
Chris@102:         template<typename Target, typename Source>
Chris@102:         struct is_arithmetic_and_not_xchars
Chris@102:         {
Chris@102:             BOOST_STATIC_CONSTANT(bool, value = (
Chris@102:                 boost::type_traits::ice_and<
Chris@102:                     boost::type_traits::ice_not<
Chris@102:                         boost::detail::is_character<Target>::value
Chris@102:                     >::value,
Chris@102:                     boost::type_traits::ice_not<
Chris@102:                         boost::detail::is_character<Source>::value
Chris@102:                     >::value,
Chris@102:                     boost::is_arithmetic<Source>::value,
Chris@102:                     boost::is_arithmetic<Target>::value       
Chris@102:                 >::value
Chris@102:             ));
Chris@102:         };
Chris@102: 
Chris@102:         /*
Chris@102:          * is_xchar_to_xchar<Target, Source>::value is true, 
Chris@102:          * Target and Souce are char types of the same size 1 (char, signed char, unsigned char).
Chris@102:          */
Chris@102:         template<typename Target, typename Source>
Chris@102:         struct is_xchar_to_xchar 
Chris@102:         {
Chris@102:             BOOST_STATIC_CONSTANT(bool, value = (
Chris@102:                 boost::type_traits::ice_and<
Chris@102:                      boost::type_traits::ice_eq<sizeof(Source), sizeof(Target)>::value,
Chris@102:                      boost::type_traits::ice_eq<sizeof(Source), sizeof(char)>::value,
Chris@102:                      boost::detail::is_character<Target>::value,
Chris@102:                      boost::detail::is_character<Source>::value
Chris@102:                 >::value
Chris@102:             ));
Chris@102:         };
Chris@102: 
Chris@102:         template<typename Target, typename Source>
Chris@102:         struct is_char_array_to_stdstring
Chris@102:             : boost::false_type
Chris@102:         {};
Chris@102: 
Chris@102:         template<typename CharT, typename Traits, typename Alloc>
Chris@102:         struct is_char_array_to_stdstring< std::basic_string<CharT, Traits, Alloc>, CharT* >
Chris@102:             : boost::true_type
Chris@102:         {};
Chris@102: 
Chris@102:         template<typename CharT, typename Traits, typename Alloc>
Chris@102:         struct is_char_array_to_stdstring< std::basic_string<CharT, Traits, Alloc>, const CharT* >
Chris@102:             : boost::true_type
Chris@102:         {};
Chris@102: 
Chris@102:         template<typename CharT, typename Traits, typename Alloc>
Chris@102:         struct is_char_array_to_stdstring< boost::container::basic_string<CharT, Traits, Alloc>, CharT* >
Chris@102:             : boost::true_type
Chris@102:         {};
Chris@102: 
Chris@102:         template<typename CharT, typename Traits, typename Alloc>
Chris@102:         struct is_char_array_to_stdstring< boost::container::basic_string<CharT, Traits, Alloc>, const CharT* >
Chris@102:             : boost::true_type
Chris@102:         {};
Chris@102: 
Chris@102:         template <typename Target, typename Source>
Chris@102:         struct copy_converter_impl
Chris@102:         {
Chris@102: // MSVC fail to forward an array (DevDiv#555157 "SILENT BAD CODEGEN triggered by perfect forwarding",
Chris@102: // fixed in 2013 RTM).
Chris@102: #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && (!defined(BOOST_MSVC) || BOOST_MSVC >= 1800)
Chris@102:             template <class T>
Chris@102:             static inline bool try_convert(T&& arg, Target& result) {
Chris@102:                 result = static_cast<T&&>(arg); // eqaul to `result = std::forward<T>(arg);`
Chris@102:                 return true;
Chris@102:             }
Chris@102: #else
Chris@102:             static inline bool try_convert(const Source& arg, Target& result) {
Chris@102:                 result = arg;
Chris@102:                 return true;
Chris@102:             }
Chris@102: #endif
Chris@102:         };
Chris@102:     }
Chris@102: 
Chris@102:     namespace conversion { namespace detail {
Chris@102: 
Chris@102:         template <typename Target, typename Source>
Chris@102:         inline bool try_lexical_convert(const Source& arg, Target& result)
Chris@102:         {
Chris@102:             typedef BOOST_DEDUCED_TYPENAME boost::detail::array_to_pointer_decay<Source>::type src;
Chris@102: 
Chris@102:             typedef BOOST_DEDUCED_TYPENAME boost::type_traits::ice_or<
Chris@102:                 boost::detail::is_xchar_to_xchar<Target, src >::value,
Chris@102:                 boost::detail::is_char_array_to_stdstring<Target, src >::value,
Chris@102:                 boost::type_traits::ice_and<
Chris@102:                      boost::is_same<Target, src >::value,
Chris@102:                      boost::detail::is_stdstring<Target >::value
Chris@102:                 >::value,
Chris@102:                 boost::type_traits::ice_and<
Chris@102:                      boost::is_same<Target, src >::value,
Chris@102:                      boost::detail::is_character<Target >::value
Chris@102:                 >::value
Chris@102:             > shall_we_copy_t;
Chris@102: 
Chris@102:             typedef boost::detail::is_arithmetic_and_not_xchars<Target, src >
Chris@102:                 shall_we_copy_with_dynamic_check_t;
Chris@102: 
Chris@102:             // We do evaluate second `if_` lazily to avoid unnecessary instantiations
Chris@102:             // of `shall_we_copy_with_dynamic_check_t` and improve compilation times.
Chris@102:             typedef BOOST_DEDUCED_TYPENAME boost::mpl::if_c<
Chris@102:                 shall_we_copy_t::value,
Chris@102:                 boost::mpl::identity<boost::detail::copy_converter_impl<Target, src > >,
Chris@102:                 boost::mpl::if_<
Chris@102:                      shall_we_copy_with_dynamic_check_t,
Chris@102:                      boost::detail::dynamic_num_converter_impl<Target, src >,
Chris@102:                      boost::detail::lexical_converter_impl<Target, src >
Chris@102:                 >
Chris@102:             >::type caster_type_lazy;
Chris@102: 
Chris@102:             typedef BOOST_DEDUCED_TYPENAME caster_type_lazy::type caster_type;
Chris@102: 
Chris@102:             return caster_type::try_convert(arg, result);
Chris@102:         }
Chris@102: 
Chris@102:         template <typename Target, typename CharacterT>
Chris@102:         inline bool try_lexical_convert(const CharacterT* chars, std::size_t count, Target& result)
Chris@102:         {
Chris@102:             BOOST_STATIC_ASSERT_MSG(
Chris@102:                 boost::detail::is_character<CharacterT>::value,
Chris@102:                 "This overload of try_lexical_convert is meant to be used only with arrays of characters."
Chris@102:             );
Chris@102:             return ::boost::conversion::detail::try_lexical_convert(
Chris@102:                 ::boost::iterator_range<const CharacterT*>(chars, chars + count), result
Chris@102:             );
Chris@102:         }
Chris@102: 
Chris@102:     }} // namespace conversion::detail
Chris@102: 
Chris@102:     namespace conversion {
Chris@102:         // ADL barrier
Chris@102:         using ::boost::conversion::detail::try_lexical_convert;
Chris@102:     }
Chris@102: 
Chris@102: } // namespace boost
Chris@102: 
Chris@102: #endif // BOOST_LEXICAL_CAST_TRY_LEXICAL_CONVERT_HPP
Chris@102: