| /*-----------------------------------------------------------------------------+ |
| Copyright (c) 2008-2009: Joachim Faulhaber |
| +------------------------------------------------------------------------------+ |
| Distributed under the Boost Software License, Version 1.0. |
| (See accompanying file LICENCE.txt or copy at |
| http://www.boost.org/LICENSE_1_0.txt) |
| +-----------------------------------------------------------------------------*/ |
| #ifndef BOOST_ICL_TYPE_TRAITS_DIFFERENCE_TYPE_OF_HPP_JOFA_080911 |
| #define BOOST_ICL_TYPE_TRAITS_DIFFERENCE_TYPE_OF_HPP_JOFA_080911 |
| |
| #include <boost/config.hpp> // For macro BOOST_STATIC_CONSTANT |
| #include <boost/type_traits/is_pointer.hpp> |
| #include <boost/mpl/has_xxx.hpp> |
| #include <boost/mpl/or.hpp> |
| #include <boost/mpl/and.hpp> |
| #include <boost/mpl/not.hpp> |
| #include <boost/icl/type_traits/no_type.hpp> |
| #include <boost/icl/type_traits/is_numeric.hpp> |
| #include <boost/icl/type_traits/rep_type_of.hpp> |
| |
| namespace boost{ namespace icl |
| { |
| namespace detail |
| { |
| BOOST_MPL_HAS_XXX_TRAIT_DEF(difference_type) |
| } |
| |
| //-------------------------------------------------------------------------- |
| template <class Type> |
| struct has_difference_type |
| : mpl::bool_<detail::has_difference_type<Type>::value> |
| {}; |
| |
| //-------------------------------------------------------------------------- |
| template<class Type> // type_of(T-T)==T |
| struct is_subtraction_closed |
| { |
| typedef is_subtraction_closed type; |
| BOOST_STATIC_CONSTANT(bool, |
| value = (mpl::or_< is_numeric<Type> |
| , mpl::and_< has_rep_type<Type> |
| , mpl::not_<has_difference_type<Type> > |
| > |
| >::value) |
| ); |
| }; |
| |
| //-------------------------------------------------------------------------- |
| template<class Type> |
| struct has_difference |
| { |
| typedef has_difference type; |
| BOOST_STATIC_CONSTANT(bool, |
| value = (mpl::or_< is_subtraction_closed<Type> |
| , is_pointer<Type> |
| , has_difference_type<Type> >::value) |
| ); |
| }; |
| |
| //-------------------------------------------------------------------------- |
| template <class Type, bool has_difference, bool has_diff_type> |
| struct get_difference_type; |
| |
| template <class Type> |
| struct get_difference_type<Type, false, false> |
| { |
| typedef no_type type; |
| }; |
| |
| template <class Type> |
| struct get_difference_type<Type*, true, false> |
| { |
| typedef std::ptrdiff_t type; |
| }; |
| |
| template <class Type> |
| struct get_difference_type<Type, true, false> |
| { |
| typedef Type type; |
| }; |
| |
| template <class Type> |
| struct get_difference_type<Type, true, true> |
| { |
| typedef typename Type::difference_type type; |
| }; |
| |
| //-------------------------------------------------------------------------- |
| template<class Type> |
| struct difference_type_of |
| { |
| typedef typename |
| get_difference_type< Type |
| , has_difference<Type>::value |
| , has_difference_type<Type>::value |
| >::type type; |
| }; |
| |
| }} // namespace boost icl |
| |
| #endif |
| |
| |