boost/type_traits/is_same.hpp
// (C) Copyright Dave Abrahams, Steve Cleary, Beman Dawes,
// Howard Hinnant and John Maddock 2000.
// (C) Copyright Mat Marcus, Jesse Jones and Adobe Systems Inc 2001
// Use, modification and distribution are subject to the Boost Software License,
// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt).
//
// See http://www.boost.org/libs/type_traits for most recent version including documentation.
// Fixed is_pointer, is_reference, is_const, is_volatile, is_same,
// is_member_pointer based on the Simulated Partial Specialization work
// of Mat Marcus and Jesse Jones. See http://opensource.adobe.com or
// http://groups.yahoo.com/group/boost/message/5441
// Some workarounds in here use ideas suggested from "Generic<Programming>:
// Mappings between Types and Values"
// by Andrei Alexandrescu (see http://www.cuj.com/experts/1810/alexandr.html).
#ifndef BOOST_TT_IS_SAME_HPP_INCLUDED
#define BOOST_TT_IS_SAME_HPP_INCLUDED
#include <boost/type_traits/config.hpp>
#ifdef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
#include <boost/type_traits/detail/yes_no_type.hpp>
#include <boost/type_traits/detail/ice_and.hpp>
#include <boost/type_traits/is_reference.hpp>
#endif
// should be the last #include
#include <boost/type_traits/detail/bool_trait_def.hpp>
namespace boost {
#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
BOOST_TT_AUX_BOOL_TRAIT_DEF2(is_same,T,U,false)
BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC2_1(typename T,is_same,T,T,true)
#if BOOST_WORKAROUND(__BORLANDC__, < 0x600)
// without this, Borland's compiler gives the wrong answer for
// references to arrays:
BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC2_1(typename T,is_same,T&,T&,true)
#endif
#else // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
namespace detail {
#ifdef BOOST_MSVC
// the following VC6 specific implementation is *NOT* legal
// C++, but has the advantage that it works for incomplete
// types.
template< typename T1 >
struct is_same_part_1
{
template<typename T2> struct part_2 { enum { value = false }; };
template<> struct part_2<T1> { enum { value = true }; };
};
template< typename T1, typename T2 >
struct is_same_impl
{
enum { value = detail::is_same_part_1<T1>::template part_2<T2>::value };
};
#else // generic "no-partial-specialization" version
template <typename T>
::boost::type_traits::yes_type
BOOST_TT_DECL is_same_tester(T*, T*);
::boost::type_traits::no_type
BOOST_TT_DECL is_same_tester(...);
template <typename T, typename U>
struct is_same_impl
{
static T t;
static U u;
BOOST_STATIC_CONSTANT(bool, value =
(::boost::type_traits::ice_and<
(sizeof(type_traits::yes_type) == sizeof(detail::is_same_tester(&t,&u))),
(::boost::is_reference<T>::value == ::boost::is_reference<U>::value),
(sizeof(T) == sizeof(U))
>::value));
};
#endif // BOOST_MSVC
} // namespace detail
BOOST_TT_AUX_BOOL_TRAIT_DEF2(is_same,T,U,(::boost::detail::is_same_impl<T,U>::value))
#endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
} // namespace boost
#include <boost/type_traits/detail/bool_trait_undef.hpp>
#endif // BOOST_TT_IS_SAME_HPP_INCLUDED