boost/type_traits/integral_promotion.hpp
// Copyright 2005 Alexander Nasonov.
// Distributed under 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)
#ifndef FILE_boost_type_traits_integral_promotion_hpp_INCLUDED
#define FILE_boost_type_traits_integral_promotion_hpp_INCLUDED
#include <boost/config.hpp>
#include <boost/mpl/eval_if.hpp>
#include <boost/mpl/identity.hpp>
#include <boost/type_traits/integral_constant.hpp>
#include <boost/type_traits/is_const.hpp>
#include <boost/type_traits/is_enum.hpp>
#include <boost/type_traits/is_volatile.hpp>
#include <boost/type_traits/remove_cv.hpp>
// Should be the last #include
#include <boost/type_traits/detail/type_trait_def.hpp>
namespace boost {
namespace type_traits { namespace detail {
// 4.5/2
template <class T> struct need_promotion : boost::is_enum<T> {};
// 4.5/1
template<> struct need_promotion<char > : true_type {};
template<> struct need_promotion<signed char > : true_type {};
template<> struct need_promotion<unsigned char > : true_type {};
template<> struct need_promotion<signed short int > : true_type {};
template<> struct need_promotion<unsigned short int> : true_type {};
// Specializations for non-standard types.
// Type is promoted if it's smaller then int.
#define BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(T) \
template<> struct need_promotion<T> \
: integral_constant<bool, (sizeof(T) < sizeof(int))> {};
// Same set of integral types as in boost/type_traits/is_integral.hpp.
// Please, keep in sync.
#if (defined(BOOST_MSVC) && (BOOST_MSVC < 1300)) \
|| (defined(BOOST_INTEL_CXX_VERSION) && defined(_MSC_VER) && (BOOST_INTEL_CXX_VERSION <= 600)) \
|| (defined(__BORLANDC__) && (__BORLANDC__ == 0x600) && (_MSC_VER < 1300))
// TODO: common macro for this #if. Or better yet, PP SEQ of non-standard types.
BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(__int8 )
BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(unsigned __int8 )
BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(__int16 )
BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(unsigned __int16)
BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(__int32 )
BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(unsigned __int32)
#ifdef __BORLANDC__
BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(unsigned __int64)
BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE( __int64)
#endif
#endif
#if defined(BOOST_HAS_LONG_LONG)
BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(boost::ulong_long_type)
BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(boost::long_long_type )
#elif defined(BOOST_HAS_MS_INT64)
BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE(unsigned __int64)
BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE( __int64)
#endif
#undef BOOST_TT_AUX_PROMOTE_NONSTANDARD_TYPE
#ifndef BOOST_NO_INTRINSIC_WCHAR_T
// 4.5/2
template<> struct need_promotion<wchar_t> : true_type {};
#endif
// 4.5/3 (integral bit-field) is not supported.
// 4.5/4
template<> struct need_promotion<bool> : true_type {};
// Get promoted type by index and cv qualifiers.
template<int Index, int IsConst, int IsVolatile> struct promote_from_index;
#define BOOST_TT_AUX_PROMOTE_FROM_INDEX(N,T) \
template<> struct promote_from_index<N,0,0> { typedef T type; }; \
template<> struct promote_from_index<N,0,1> { typedef T volatile type; }; \
template<> struct promote_from_index<N,1,0> { typedef T const type; }; \
template<> struct promote_from_index<N,1,1> { typedef T const volatile type; };
BOOST_TT_AUX_PROMOTE_FROM_INDEX(1, int )
BOOST_TT_AUX_PROMOTE_FROM_INDEX(2, unsigned int )
BOOST_TT_AUX_PROMOTE_FROM_INDEX(3, long )
BOOST_TT_AUX_PROMOTE_FROM_INDEX(4, unsigned long)
// WARNING: integral promotions to non-standard types
// long long and __int64 are not defined by the standard.
// Additional specialisations and overloads shouldn't
// introduce ambiguity, though.
#if defined(BOOST_HAS_LONG_LONG)
BOOST_TT_AUX_PROMOTE_FROM_INDEX(5, boost::long_long_type )
BOOST_TT_AUX_PROMOTE_FROM_INDEX(6, boost::ulong_long_type)
#elif defined(BOOST_HAS_MS_INT64)
BOOST_TT_AUX_PROMOTE_FROM_INDEX(7, __int64 )
BOOST_TT_AUX_PROMOTE_FROM_INDEX(8, unsigned __int64)
#endif
#undef BOOST_TT_AUX_PROMOTE_FROM_INDEX
// Define BOOST_TT_AUX_PROMOTED_INDEX_TESTER:
#if !defined(BOOST_MSVC)
template<int N>
struct sized_type_for_promotion
{
typedef char (&type)[N];
};
#define BOOST_TT_AUX_PROMOTED_INDEX_TESTER(I,T) \
sized_type_for_promotion<I>::type promoted_index_tester(T);
#else
#define BOOST_TT_AUX_PROMOTED_INDEX_TESTER(I,T) \
char (&promoted_index_tester(T))[I];
#endif
BOOST_TT_AUX_PROMOTED_INDEX_TESTER(1, int )
BOOST_TT_AUX_PROMOTED_INDEX_TESTER(2, unsigned int )
BOOST_TT_AUX_PROMOTED_INDEX_TESTER(3, long )
BOOST_TT_AUX_PROMOTED_INDEX_TESTER(4, unsigned long)
#if defined(BOOST_HAS_LONG_LONG)
BOOST_TT_AUX_PROMOTED_INDEX_TESTER(5, boost::long_long_type )
BOOST_TT_AUX_PROMOTED_INDEX_TESTER(6, boost::ulong_long_type)
#elif defined(BOOST_HAS_MS_INT64)
BOOST_TT_AUX_PROMOTED_INDEX_TESTER(7, __int64 )
BOOST_TT_AUX_PROMOTED_INDEX_TESTER(8, unsigned __int64)
#endif
#undef BOOST_TT_AUX_PROMOTED_INDEX_TESTER
// Get an index of promoted type for type T.
// Precondition: need_promotion<T>
template<class T>
struct promoted_index
{
static T testee; // undefined
BOOST_STATIC_CONSTANT(int, value = sizeof(promoted_index_tester(+testee)) );
// Unary plus promotes testee LOOK HERE ---> ^
};
template<class T>
struct integral_promotion_impl
{
typedef BOOST_DEDUCED_TYPENAME promote_from_index<
(boost::type_traits::detail::promoted_index<T>::value)
, (boost::is_const<T>::value)
, (boost::is_volatile<T>::value)
>::type type;
};
template<class T>
struct integral_promotion
: boost::mpl::eval_if<
need_promotion<BOOST_DEDUCED_TYPENAME remove_cv<T>::type>
, integral_promotion_impl<T>
, boost::mpl::identity<T>
>
{
};
} }
BOOST_TT_AUX_TYPE_TRAIT_DEF1(
integral_promotion
, T
, BOOST_DEDUCED_TYPENAME
boost::type_traits::detail::integral_promotion<T>::type
)
}
#include <boost/type_traits/detail/type_trait_undef.hpp>
#endif // #ifndef FILE_boost_type_traits_integral_promotion_hpp_INCLUDED