1 2 // (C) Copyright Dave Abrahams, Steve Cleary, Beman Dawes, 3 // Howard Hinnant and John Maddock 2000. 4 // (C) Copyright Mat Marcus, Jesse Jones and Adobe Systems Inc 2001 5 6 // Use, modification and distribution are subject to the Boost Software License, 7 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at 8 // http://www.boost.org/LICENSE_1_0.txt). 9 // 10 // See http://www.boost.org/libs/type_traits for most recent version including documentation. 11 12 // Fixed is_pointer, is_reference, is_const, is_volatile, is_same, 13 // is_member_pointer based on the Simulated Partial Specialization work 14 // of Mat Marcus and Jesse Jones. See http://opensource.adobe.com or 15 // http://groups.yahoo.com/group/boost/message/5441 16 // Some workarounds in here use ideas suggested from "Generic<Programming>: 17 // Mappings between Types and Values" 18 // by Andrei Alexandrescu (see http://www.cuj.com/experts/1810/alexandr.html). 19 20 21 #ifndef BOOST_TT_IS_SAME_HPP_INCLUDED 22 #define BOOST_TT_IS_SAME_HPP_INCLUDED 23 24 #include <boost/type_traits/config.hpp> 25 #ifdef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION 26 #include <boost/type_traits/detail/yes_no_type.hpp> 27 #include <boost/type_traits/detail/ice_and.hpp> 28 #include <boost/type_traits/is_reference.hpp> 29 #endif 30 // should be the last #include 31 #include <boost/type_traits/detail/bool_trait_def.hpp> 32 33 namespace boost { 34 35 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION 36 37 BOOST_TT_AUX_BOOL_TRAIT_DEF2(is_same,T,U,false) 38 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC2_1(typename T,is_same,T,T,true) 39 #if BOOST_WORKAROUND(__BORLANDC__, < 0x600) 40 // without this, Borland's compiler gives the wrong answer for 41 // references to arrays: 42 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC2_1(typename T,is_same,T&,T&,true) 43 #endif 44 45 #else // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION 46 47 namespace detail { 48 49 #ifdef BOOST_MSVC 50 // the following VC6 specific implementation is *NOT* legal 51 // C++, but has the advantage that it works for incomplete 52 // types. 53 54 template< typename T1 > 55 struct is_same_part_1 56 { 57 template<typename T2> struct part_2 { enum { value = false }; }; 58 template<> struct part_2<T1> { enum { value = true }; }; 59 }; 60 61 template< typename T1, typename T2 > 62 struct is_same_impl 63 { 64 enum { value = boost::detail::is_same_part_1<T1>::template part_2<T2>::value }; 65 }; 66 67 #else // generic "no-partial-specialization" version 68 69 template <typename T> 70 ::boost::type_traits::yes_type 71 BOOST_TT_DECL is_same_tester(T*, T*); 72 73 ::boost::type_traits::no_type 74 BOOST_TT_DECL is_same_tester(...); 75 76 template <typename T, typename U> 77 struct is_same_impl 78 { 79 static T t; 80 static U u; 81 82 BOOST_STATIC_CONSTANT(bool, value = 83 (::boost::type_traits::ice_and< 84 (sizeof(type_traits::yes_type) == sizeof(boost::detail::is_same_tester(&t,&u))), 85 (::boost::is_reference<T>::value == ::boost::is_reference<U>::value), 86 (sizeof(T) == sizeof(U)) 87 >::value)); 88 }; 89 90 #endif // BOOST_MSVC 91 92 } // namespace detail 93 94 BOOST_TT_AUX_BOOL_TRAIT_DEF2(is_same,T,U,(::boost::detail::is_same_impl<T,U>::value)) 95 96 #endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION 97 98 } // namespace boost 99 100 #include <boost/type_traits/detail/bool_trait_undef.hpp> 101 102 #endif // BOOST_TT_IS_SAME_HPP_INCLUDED 103 104