git.sesse.net Git - casparcg/blob - dependencies64/boost/boost/lexical_cast/try_lexical_convert.hpp

   1 // Copyright Kevlin Henney, 2000-2005.
   2 // Copyright Alexander Nasonov, 2006-2010.
   3 // Copyright Antony Polukhin, 2011-2014.
   4 //
   5 // Distributed under the Boost Software License, Version 1.0. (See
   6 // accompanying file LICENSE_1_0.txt or copy at
   7 // http://www.boost.org/LICENSE_1_0.txt)
   8 //
   9 // what:  lexical_cast custom keyword cast
  10 // who:   contributed by Kevlin Henney,
  11 //        enhanced with contributions from Terje Slettebo,
  12 //        with additional fixes and suggestions from Gennaro Prota,
  13 //        Beman Dawes, Dave Abrahams, Daryle Walker, Peter Dimov,
  14 //        Alexander Nasonov, Antony Polukhin, Justin Viiret, Michael Hofmann,
  15 //        Cheng Yang, Matthew Bradbury, David W. Birdsall, Pavel Korzh and other Boosters
  16 // when:  November 2000, March 2003, June 2005, June 2006, March 2011 - 2014
  17
  18 #ifndef BOOST_LEXICAL_CAST_TRY_LEXICAL_CONVERT_HPP
  19 #define BOOST_LEXICAL_CAST_TRY_LEXICAL_CONVERT_HPP
  20
  21 #include <boost/config.hpp>
  22 #ifdef BOOST_HAS_PRAGMA_ONCE
  23 #   pragma once
  24 #endif
  25
  26 #include <string>
  27 #include <boost/mpl/bool.hpp>
  28 #include <boost/mpl/identity.hpp>
  29 #include <boost/mpl/if.hpp>
  30 #include <boost/type_traits/is_same.hpp>
  31 #include <boost/type_traits/is_arithmetic.hpp>
  32
  33 #include <boost/lexical_cast/detail/is_character.hpp>
  34 #include <boost/lexical_cast/detail/converter_numeric.hpp>
  35 #include <boost/lexical_cast/detail/converter_lexical.hpp>
  36
  37 #include <boost/range/iterator_range_core.hpp>
  38 #include <boost/container/container_fwd.hpp>
  39
  40 namespace boost {
  41     namespace detail
  42     {
  43         template<typename T>
  44         struct is_stdstring
  45             : boost::false_type
  46         {};
  47
  48         template<typename CharT, typename Traits, typename Alloc>
  49         struct is_stdstring< std::basic_string<CharT, Traits, Alloc> >
  50             : boost::true_type
  51         {};
  52
  53         template<typename CharT, typename Traits, typename Alloc>
  54         struct is_stdstring< boost::container::basic_string<CharT, Traits, Alloc> >
  55             : boost::true_type
  56         {};
  57
  58         template<typename Target, typename Source>
  59         struct is_arithmetic_and_not_xchars
  60         {
  61             typedef boost::mpl::bool_<
  62                     !(boost::detail::is_character<Target>::value) &&
  63                     !(boost::detail::is_character<Source>::value) &&
  64                     boost::is_arithmetic<Source>::value &&
  65                     boost::is_arithmetic<Target>::value
  66                 > type;
  67
  68             BOOST_STATIC_CONSTANT(bool, value = (
  69                 type::value
  70             ));
  71         };
  72
  73         /*
  74          * is_xchar_to_xchar<Target, Source>::value is true,
  75          * Target and Souce are char types of the same size 1 (char, signed char, unsigned char).
  76          */
  77         template<typename Target, typename Source>
  78         struct is_xchar_to_xchar
  79         {
  80             typedef boost::mpl::bool_<
  81                      sizeof(Source) == sizeof(Target) &&
  82                      sizeof(Source) == sizeof(char) &&
  83                      boost::detail::is_character<Target>::value &&
  84                      boost::detail::is_character<Source>::value
  85                 > type;
  86
  87             BOOST_STATIC_CONSTANT(bool, value = (
  88                 type::value
  89             ));
  90         };
  91
  92         template<typename Target, typename Source>
  93         struct is_char_array_to_stdstring
  94             : boost::false_type
  95         {};
  96
  97         template<typename CharT, typename Traits, typename Alloc>
  98         struct is_char_array_to_stdstring< std::basic_string<CharT, Traits, Alloc>, CharT* >
  99             : boost::true_type
 100         {};
 101
 102         template<typename CharT, typename Traits, typename Alloc>
 103         struct is_char_array_to_stdstring< std::basic_string<CharT, Traits, Alloc>, const CharT* >
 104             : boost::true_type
 105         {};
 106
 107         template<typename CharT, typename Traits, typename Alloc>
 108         struct is_char_array_to_stdstring< boost::container::basic_string<CharT, Traits, Alloc>, CharT* >
 109             : boost::true_type
 110         {};
 111
 112         template<typename CharT, typename Traits, typename Alloc>
 113         struct is_char_array_to_stdstring< boost::container::basic_string<CharT, Traits, Alloc>, const CharT* >
 114             : boost::true_type
 115         {};
 116
 117         template <typename Target, typename Source>
 118         struct copy_converter_impl
 119         {
 120 // MSVC fail to forward an array (DevDiv#555157 "SILENT BAD CODEGEN triggered by perfect forwarding",
 121 // fixed in 2013 RTM).
 122 #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && (!defined(BOOST_MSVC) || BOOST_MSVC >= 1800)
 123             template <class T>
 124             static inline bool try_convert(T&& arg, Target& result) {
 125                 result = static_cast<T&&>(arg); // eqaul to `result = std::forward<T>(arg);`
 126                 return true;
 127             }
 128 #else
 129             static inline bool try_convert(const Source& arg, Target& result) {
 130                 result = arg;
 131                 return true;
 132             }
 133 #endif
 134         };
 135     }
 136
 137     namespace conversion { namespace detail {
 138
 139         template <typename Target, typename Source>
 140         inline bool try_lexical_convert(const Source& arg, Target& result)
 141         {
 142             typedef BOOST_DEDUCED_TYPENAME boost::detail::array_to_pointer_decay<Source>::type src;
 143
 144             typedef boost::mpl::bool_<
 145                 boost::detail::is_xchar_to_xchar<Target, src >::value ||
 146                 boost::detail::is_char_array_to_stdstring<Target, src >::value ||
 147                 (
 148                      boost::is_same<Target, src >::value &&
 149                      boost::detail::is_stdstring<Target >::value
 150                 ) ||
 151                 (
 152                      boost::is_same<Target, src >::value &&
 153                      boost::detail::is_character<Target >::value
 154                 )
 155             > shall_we_copy_t;
 156
 157             typedef boost::detail::is_arithmetic_and_not_xchars<Target, src >
 158                 shall_we_copy_with_dynamic_check_t;
 159
 160             // We do evaluate second `if_` lazily to avoid unnecessary instantiations
 161             // of `shall_we_copy_with_dynamic_check_t` and improve compilation times.
 162             typedef BOOST_DEDUCED_TYPENAME boost::mpl::if_c<
 163                 shall_we_copy_t::value,
 164                 boost::mpl::identity<boost::detail::copy_converter_impl<Target, src > >,
 165                 boost::mpl::if_<
 166                      shall_we_copy_with_dynamic_check_t,
 167                      boost::detail::dynamic_num_converter_impl<Target, src >,
 168                      boost::detail::lexical_converter_impl<Target, src >
 169                 >
 170             >::type caster_type_lazy;
 171
 172             typedef BOOST_DEDUCED_TYPENAME caster_type_lazy::type caster_type;
 173
 174             return caster_type::try_convert(arg, result);
 175         }
 176
 177         template <typename Target, typename CharacterT>
 178         inline bool try_lexical_convert(const CharacterT* chars, std::size_t count, Target& result)
 179         {
 180             BOOST_STATIC_ASSERT_MSG(
 181                 boost::detail::is_character<CharacterT>::value,
 182                 "This overload of try_lexical_convert is meant to be used only with arrays of characters."
 183             );
 184             return ::boost::conversion::detail::try_lexical_convert(
 185                 ::boost::iterator_range<const CharacterT*>(chars, chars + count), result
 186             );
 187         }
 188
 189     }} // namespace conversion::detail
 190
 191     namespace conversion {
 192         // ADL barrier
 193         using ::boost::conversion::detail::try_lexical_convert;
 194     }
 195
 196 } // namespace boost
 197
 198 #endif // BOOST_LEXICAL_CAST_TRY_LEXICAL_CONVERT_HPP
 199