ceph/src/boost/boost/lexical_cast/try_lexical_convert.hpp

   1 // Copyright Kevlin Henney, 2000-2005.
   2 // Copyright Alexander Nasonov, 2006-2010.
   3 // Copyright Antony Polukhin, 2011-2016.
   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 #if defined(__clang__) || (defined(__GNUC__) && \
  27     !(defined(__INTEL_COMPILER) || defined(__ICL) || defined(__ICC) || defined(__ECC)) && \
  28     (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)))
  29 #pragma GCC diagnostic push
  30 #pragma GCC diagnostic ignored "-Wuninitialized"
  31 #endif
  32
  33 #include <string>
  34 #include <boost/mpl/bool.hpp>
  35 #include <boost/mpl/identity.hpp>
  36 #include <boost/mpl/if.hpp>
  37 #include <boost/type_traits/is_same.hpp>
  38 #include <boost/type_traits/is_arithmetic.hpp>
  39
  40 #include <boost/lexical_cast/detail/is_character.hpp>
  41 #include <boost/lexical_cast/detail/converter_numeric.hpp>
  42 #include <boost/lexical_cast/detail/converter_lexical.hpp>
  43
  44 #include <boost/range/iterator_range_core.hpp>
  45 #include <boost/container/container_fwd.hpp>
  46
  47 namespace boost {
  48     namespace detail
  49     {
  50         template<typename T>
  51         struct is_stdstring
  52             : boost::false_type
  53         {};
  54
  55         template<typename CharT, typename Traits, typename Alloc>
  56         struct is_stdstring< std::basic_string<CharT, Traits, Alloc> >
  57             : boost::true_type
  58         {};
  59
  60         // Sun Studio has problem with partial specialization of templates differing only in namespace.
  61         // We workaround that by making `is_booststring` trait, instead of specializing `is_stdstring` for `boost::container::basic_string`.
  62         template<typename T>
  63         struct is_booststring
  64             : boost::false_type
  65         {};
  66
  67         template<typename CharT, typename Traits, typename Alloc>
  68         struct is_booststring< boost::container::basic_string<CharT, Traits, Alloc> >
  69             : boost::true_type
  70         {};
  71
  72         template<typename Target, typename Source>
  73         struct is_arithmetic_and_not_xchars
  74         {
  75             typedef boost::mpl::bool_<
  76                     !(boost::detail::is_character<Target>::value) &&
  77                     !(boost::detail::is_character<Source>::value) &&
  78                     boost::is_arithmetic<Source>::value &&
  79                     boost::is_arithmetic<Target>::value
  80                 > type;
  81
  82             BOOST_STATIC_CONSTANT(bool, value = (
  83                 type::value
  84             ));
  85         };
  86
  87         /*
  88          * is_xchar_to_xchar<Target, Source>::value is true,
  89          * Target and Souce are char types of the same size 1 (char, signed char, unsigned char).
  90          */
  91         template<typename Target, typename Source>
  92         struct is_xchar_to_xchar
  93         {
  94             typedef boost::mpl::bool_<
  95                      sizeof(Source) == sizeof(Target) &&
  96                      sizeof(Source) == sizeof(char) &&
  97                      boost::detail::is_character<Target>::value &&
  98                      boost::detail::is_character<Source>::value
  99                 > type;
 100
 101             BOOST_STATIC_CONSTANT(bool, value = (
 102                 type::value
 103             ));
 104         };
 105
 106         template<typename Target, typename Source>
 107         struct is_char_array_to_stdstring
 108             : boost::false_type
 109         {};
 110
 111         template<typename CharT, typename Traits, typename Alloc>
 112         struct is_char_array_to_stdstring< std::basic_string<CharT, Traits, Alloc>, CharT* >
 113             : boost::true_type
 114         {};
 115
 116         template<typename CharT, typename Traits, typename Alloc>
 117         struct is_char_array_to_stdstring< std::basic_string<CharT, Traits, Alloc>, const CharT* >
 118             : boost::true_type
 119         {};
 120
 121         // Sun Studio has problem with partial specialization of templates differing only in namespace.
 122         // We workaround that by making `is_char_array_to_booststring` trait, instead of specializing `is_char_array_to_stdstring` for `boost::container::basic_string`.
 123         template<typename Target, typename Source>
 124         struct is_char_array_to_booststring
 125             : boost::false_type
 126         {};
 127
 128         template<typename CharT, typename Traits, typename Alloc>
 129         struct is_char_array_to_booststring< boost::container::basic_string<CharT, Traits, Alloc>, CharT* >
 130             : boost::true_type
 131         {};
 132
 133         template<typename CharT, typename Traits, typename Alloc>
 134         struct is_char_array_to_booststring< boost::container::basic_string<CharT, Traits, Alloc>, const CharT* >
 135             : boost::true_type
 136         {};
 137
 138         template <typename Target, typename Source>
 139         struct copy_converter_impl
 140         {
 141 // MSVC fail to forward an array (DevDiv#555157 "SILENT BAD CODEGEN triggered by perfect forwarding",
 142 // fixed in 2013 RTM).
 143 #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && (!defined(BOOST_MSVC) || BOOST_MSVC >= 1800)
 144             template <class T>
 145             static inline bool try_convert(T&& arg, Target& result) {
 146                 result = static_cast<T&&>(arg); // eqaul to `result = std::forward<T>(arg);`
 147                 return true;
 148             }
 149 #else
 150             static inline bool try_convert(const Source& arg, Target& result) {
 151                 result = arg;
 152                 return true;
 153             }
 154 #endif
 155         };
 156     }
 157
 158     namespace conversion { namespace detail {
 159
 160         template <typename Target, typename Source>
 161         inline bool try_lexical_convert(const Source& arg, Target& result)
 162         {
 163             typedef BOOST_DEDUCED_TYPENAME boost::detail::array_to_pointer_decay<Source>::type src;
 164
 165             typedef boost::mpl::bool_<
 166                 boost::detail::is_xchar_to_xchar<Target, src >::value ||
 167                 boost::detail::is_char_array_to_stdstring<Target, src >::value ||
 168                 boost::detail::is_char_array_to_booststring<Target, src >::value ||
 169                 (
 170                      boost::is_same<Target, src >::value &&
 171                      (boost::detail::is_stdstring<Target >::value || boost::detail::is_booststring<Target >::value)
 172                 ) ||
 173                 (
 174                      boost::is_same<Target, src >::value &&
 175                      boost::detail::is_character<Target >::value
 176                 )
 177             > shall_we_copy_t;
 178
 179             typedef boost::detail::is_arithmetic_and_not_xchars<Target, src >
 180                 shall_we_copy_with_dynamic_check_t;
 181
 182             // We do evaluate second `if_` lazily to avoid unnecessary instantiations
 183             // of `shall_we_copy_with_dynamic_check_t` and improve compilation times.
 184             typedef BOOST_DEDUCED_TYPENAME boost::mpl::if_c<
 185                 shall_we_copy_t::value,
 186                 boost::mpl::identity<boost::detail::copy_converter_impl<Target, src > >,
 187                 boost::mpl::if_<
 188                      shall_we_copy_with_dynamic_check_t,
 189                      boost::detail::dynamic_num_converter_impl<Target, src >,
 190                      boost::detail::lexical_converter_impl<Target, src >
 191                 >
 192             >::type caster_type_lazy;
 193
 194             typedef BOOST_DEDUCED_TYPENAME caster_type_lazy::type caster_type;
 195
 196             return caster_type::try_convert(arg, result);
 197         }
 198
 199         template <typename Target, typename CharacterT>
 200         inline bool try_lexical_convert(const CharacterT* chars, std::size_t count, Target& result)
 201         {
 202             BOOST_STATIC_ASSERT_MSG(
 203                 boost::detail::is_character<CharacterT>::value,
 204                 "This overload of try_lexical_convert is meant to be used only with arrays of characters."
 205             );
 206             return ::boost::conversion::detail::try_lexical_convert(
 207                 ::boost::iterator_range<const CharacterT*>(chars, chars + count), result
 208             );
 209         }
 210
 211     }} // namespace conversion::detail
 212
 213     namespace conversion {
 214         // ADL barrier
 215         using ::boost::conversion::detail::try_lexical_convert;
 216     }
 217
 218 } // namespace boost
 219
 220 #if defined(__clang__) || (defined(__GNUC__) && \
 221     !(defined(__INTEL_COMPILER) || defined(__ICL) || defined(__ICC) || defined(__ECC)) && \
 222     (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)))
 223 #pragma GCC diagnostic pop
 224 #endif
 225
 226 #endif // BOOST_LEXICAL_CAST_TRY_LEXICAL_CONVERT_HPP
 227