boost/type_traits/integral_promotion.hpp

   1 // Copyright 2005 Alexander Nasonov.
   2 // Distributed under the Boost Software License, Version 1.0. (See
   3 // accompanying file LICENSE_1_0.txt or copy at
   4 // http://www.boost.org/LICENSE_1_0.txt)
   5
   6 #ifndef FILE_boost_type_traits_integral_promotion_hpp_INCLUDED
   7 #define FILE_boost_type_traits_integral_promotion_hpp_INCLUDED
   8
   9 #include <boost/config.hpp>
  10
  11 #include <boost/mpl/eval_if.hpp>
  12 #include <boost/mpl/identity.hpp>
  13 #include <boost/type_traits/integral_constant.hpp>
  14 #include <boost/type_traits/is_const.hpp>
  15 #include <boost/type_traits/is_enum.hpp>
  16 #include <boost/type_traits/is_volatile.hpp>
  17 #include <boost/type_traits/remove_cv.hpp>
  18
  19 // Should be the last #include
  20 #include <boost/type_traits/detail/type_trait_def.hpp>
  21
  22 namespace boost {
  23
  24 namespace type_traits { namespace detail {
  25
  26 // 4.5/2
  27 template <class T> struct need_promotion : public boost::is_enum<T> {};
  28
  29 // 4.5/1
  30 template<> struct need_promotion<char              > : public true_type {};
  31 template<> struct need_promotion<signed char       > : public true_type {};
  32 template<> struct need_promotion<unsigned char     > : public true_type {};
  33 template<> struct need_promotion<signed short int  > : public true_type {};
  34 template<> struct need_promotion<unsigned short int> : public true_type {};
  35
  36
  37 // Specializations for non-standard types.
  38 // Type is promoted if it's smaller then int.
  39
  40 #define BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(T) \
  41     template<> struct need_promotion<T>          \
  42         : public integral_constant<bool, (sizeof(T) < sizeof(int))> {};
  43
  44 // Same set of integral types as in boost/type_traits/is_integral.hpp.
  45 // Please, keep in sync.
  46 #if (defined(BOOST_MSVC) && (BOOST_MSVC < 1300)) \
  47     || (defined(BOOST_INTEL_CXX_VERSION) && defined(_MSC_VER) && (BOOST_INTEL_CXX_VERSION <= 600)) \
  48     || (defined(__BORLANDC__) && (__BORLANDC__ == 0x600) && (_MSC_VER < 1300))
  49 // TODO: common macro for this #if. Or better yet, PP SEQ of non-standard types.
  50 BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(__int8          )
  51 BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(unsigned __int8 )
  52 BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(__int16         )
  53 BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(unsigned __int16)
  54 BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(__int32         )
  55 BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(unsigned __int32)
  56 #ifdef __BORLANDC__
  57 BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(unsigned __int64)
  58 BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(         __int64)
  59 #endif
  60 #endif
  61
  62 #if defined(BOOST_HAS_LONG_LONG)
  63 BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(boost::ulong_long_type)
  64 BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(boost::long_long_type )
  65 #elif defined(BOOST_HAS_MS_INT64)
  66 BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(unsigned __int64)
  67 BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(         __int64)
  68 #endif
  69
  70 #undef BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE
  71
  72
  73 #ifndef BOOST_NO_INTRINSIC_WCHAR_T
  74 // 4.5/2
  75 template<> struct need_promotion<wchar_t> : public true_type {};
  76 #endif
  77
  78 // 4.5/3 (integral bit-field) is not supported.
  79
  80 // 4.5/4
  81 template<> struct need_promotion<bool> : public true_type {};
  82
  83
  84 // Get promoted type by index and cv qualifiers.
  85
  86 template<int Index, int IsConst, int IsVolatile> struct promote_from_index;
  87
  88 #define BOOST_TT_AUX_PROMOTE_FROM_INDEX(N,T)                                   \
  89     template<> struct promote_from_index<N,0,0> { typedef T type; };           \
  90     template<> struct promote_from_index<N,0,1> { typedef T volatile type; };  \
  91     template<> struct promote_from_index<N,1,0> { typedef T const type; };     \
  92     template<> struct promote_from_index<N,1,1> { typedef T const volatile type; };
  93
  94
  95 BOOST_TT_AUX_PROMOTE_FROM_INDEX(1, int          )
  96 BOOST_TT_AUX_PROMOTE_FROM_INDEX(2, unsigned int )
  97 BOOST_TT_AUX_PROMOTE_FROM_INDEX(3, long         )
  98 BOOST_TT_AUX_PROMOTE_FROM_INDEX(4, unsigned long)
  99
 100
 101 // WARNING: integral promotions to non-standard types
 102 // long long and __int64 are not defined by the standard.
 103 // Additional specialisations and overloads shouldn't
 104 // introduce ambiguity, though.
 105
 106 #if defined(BOOST_HAS_LONG_LONG)
 107 BOOST_TT_AUX_PROMOTE_FROM_INDEX(5, boost::long_long_type )
 108 BOOST_TT_AUX_PROMOTE_FROM_INDEX(6, boost::ulong_long_type)
 109 #elif defined(BOOST_HAS_MS_INT64)
 110 BOOST_TT_AUX_PROMOTE_FROM_INDEX(7, __int64         )
 111 BOOST_TT_AUX_PROMOTE_FROM_INDEX(8, unsigned __int64)
 112 #endif
 113
 114 #undef BOOST_TT_AUX_PROMOTE_FROM_INDEX
 115
 116
 117 // Define BOOST_TT_AUX_PROMOTED_INDEX_TESTER:
 118 #if !defined(BOOST_MSVC)
 119
 120 template<int N>
 121 struct sized_type_for_promotion
 122 {
 123     typedef char (&type)[N];
 124 };
 125
 126 #define BOOST_TT_AUX_PROMOTED_INDEX_TESTER(I,T) \
 127     sized_type_for_promotion<I>::type promoted_index_tester(T);
 128
 129 #else
 130
 131 #define BOOST_TT_AUX_PROMOTED_INDEX_TESTER(I,T) \
 132     char (&promoted_index_tester(T))[I];
 133
 134 #endif
 135
 136 BOOST_TT_AUX_PROMOTED_INDEX_TESTER(1, int          )
 137 BOOST_TT_AUX_PROMOTED_INDEX_TESTER(2, unsigned int )
 138 BOOST_TT_AUX_PROMOTED_INDEX_TESTER(3, long         )
 139 BOOST_TT_AUX_PROMOTED_INDEX_TESTER(4, unsigned long)
 140
 141 #if defined(BOOST_HAS_LONG_LONG)
 142 BOOST_TT_AUX_PROMOTED_INDEX_TESTER(5, boost::long_long_type )
 143 BOOST_TT_AUX_PROMOTED_INDEX_TESTER(6, boost::ulong_long_type)
 144 #elif defined(BOOST_HAS_MS_INT64)
 145 BOOST_TT_AUX_PROMOTED_INDEX_TESTER(7, __int64         )
 146 BOOST_TT_AUX_PROMOTED_INDEX_TESTER(8, unsigned __int64)
 147 #endif
 148
 149 #undef BOOST_TT_AUX_PROMOTED_INDEX_TESTER
 150
 151
 152 // Get an index of promoted type for type T.
 153 // Precondition: need_promotion<T>
 154 template<class T>
 155 struct promoted_index
 156 {
 157     static T testee; // undefined
 158     BOOST_STATIC_CONSTANT(int, value = sizeof(promoted_index_tester(+testee)) );
 159     // Unary plus promotes testee                    LOOK HERE ---> ^
 160 };
 161
 162 template<class T>
 163 struct integral_promotion_impl
 164 {
 165     typedef BOOST_DEDUCED_TYPENAME promote_from_index<
 166         (boost::type_traits::detail::promoted_index<T>::value)
 167       , (boost::is_const<T>::value)
 168       , (boost::is_volatile<T>::value)
 169       >::type type;
 170 };
 171
 172 template<class T>
 173 struct integral_promotion
 174   : public boost::mpl::eval_if<
 175         need_promotion<BOOST_DEDUCED_TYPENAME remove_cv<T>::type>
 176       , integral_promotion_impl<T>
 177       , boost::mpl::identity<T>
 178       >
 179 {
 180 };
 181
 182 } }
 183
 184 BOOST_TT_AUX_TYPE_TRAIT_DEF1(
 185       integral_promotion
 186     , T
 187     , BOOST_DEDUCED_TYPENAME
 188         boost::type_traits::detail::integral_promotion<T>::type
 189     )
 190 }
 191
 192 #include <boost/type_traits/detail/type_trait_undef.hpp>
 193
 194 #endif // #ifndef FILE_boost_type_traits_integral_promotion_hpp_INCLUDED
 195