boost/boost/type_traits/is_same.hpp

   1
   2 // (C) Copyright Steve Cleary, Beman Dawes, Aleksey Gurtovoy,
   3 // Howard Hinnant & John Maddock 2000.
   4 // Permission to copy, use, modify, sell and distribute this software is
   5 // granted provided this copyright notice appears in all copies. This
   6 // software is provided "as is" without express or implied warranty, and
   7 // with no claim as to its suitability for any purpose.
   8 //
   9 // See http://www.boost.org for most recent version including documentation.
  10
  11 #ifndef BOOST_TT_IS_SAME_HPP_INCLUDED
  12 #define BOOST_TT_IS_SAME_HPP_INCLUDED
  13
  14 #include "boost/type_traits/config.hpp"
  15 #ifdef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
  16 #include "boost/type_traits/detail/yes_no_type.hpp"
  17 #include "boost/type_traits/detail/ice_and.hpp"
  18 #include "boost/type_traits/is_reference.hpp"
  19 #endif
  20 // should be the last #include
  21 #include "boost/type_traits/detail/bool_trait_def.hpp"
  22
  23 namespace boost {
  24
  25 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
  26
  27 BOOST_TT_AUX_BOOL_TRAIT_DEF2(is_same,T,U,false)
  28 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC2_1(typename T,is_same,T,T,true)
  29 #ifdef __BORLANDC__
  30 // without this, Borland's compiler gives the wrong answer for
  31 // references to arrays:
  32 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC2_1(typename T,is_same,T&,T&,true)
  33 #endif
  34
  35 #else // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
  36
  37 namespace detail {
  38
  39 #ifdef BOOST_MSVC
  40 // the following VC6 specific implementation is *NOT* legal
  41 // C++, but has the advantage that it works for incomplete
  42 // types.
  43
  44 template< typename T1 >
  45 struct is_same_part_1
  46 {
  47     template<typename T2>  struct part_2     { enum { value = false }; };
  48     template<>             struct part_2<T1> { enum { value = true }; };
  49 };
  50
  51 template< typename T1, typename T2 >
  52 struct is_same_impl
  53 {
  54     enum { value = detail::is_same_part_1<T1>::template part_2<T2>::value };
  55 };
  56
  57 #else // generic "no-partial-specialization" version
  58
  59 template <typename T>
  60 ::boost::type_traits::yes_type
  61 BOOST_TT_DECL is_same_tester(T*, T*);
  62
  63 ::boost::type_traits::no_type
  64 BOOST_TT_DECL is_same_tester(...);
  65
  66 template <typename T, typename U>
  67 struct is_same_impl
  68 {
  69    static T t;
  70    static U u;
  71
  72    BOOST_STATIC_CONSTANT(bool, value =
  73       (::boost::type_traits::ice_and<
  74          (sizeof(type_traits::yes_type) == sizeof(detail::is_same_tester(&t,&u))),
  75          (::boost::is_reference<T>::value == ::boost::is_reference<U>::value),
  76          (sizeof(T) == sizeof(U))
  77         >::value));
  78 };
  79
  80 #endif // BOOST_MSVC
  81
  82 } // namespace detail
  83
  84 BOOST_TT_AUX_BOOL_TRAIT_DEF2(is_same,T,U,(::boost::detail::is_same_impl<T,U>::value))
  85
  86 #endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
  87
  88 } // namespace boost
  89
  90 #include "boost/type_traits/detail/bool_trait_undef.hpp"
  91
  92 #endif  // BOOST_TT_IS_SAME_HPP_INCLUDED
  93