| // |
| // Boost.Pointer Container |
| // |
| // Copyright Thorsten Ottosen 2003-2005. Use, modification and |
| // distribution is 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) |
| // |
| // For more information, see http://www.boost.org/libs/ptr_container/ |
| // |
| |
| |
| #ifndef BOOST_INDIRECT_CONTAINER_NULLABLE_HPP |
| #define BOOST_INDIRECT_CONTAINER_NULLABLE_HPP |
| |
| #if defined(_MSC_VER) && (_MSC_VER >= 1200) |
| # pragma once |
| #endif |
| |
| #include <boost/type_traits/detail/yes_no_type.hpp> |
| #include <boost/mpl/eval_if.hpp> |
| #include <boost/mpl/identity.hpp> |
| #include <boost/config.hpp> |
| |
| namespace boost |
| { |
| |
| template< class T > |
| struct nullable |
| { |
| typedef T type; |
| }; |
| |
| namespace ptr_container_detail |
| { |
| template< class T > |
| type_traits::yes_type is_nullable( const nullable<T>* ); |
| |
| type_traits::no_type is_nullable( ... ); |
| } |
| |
| template< class T > |
| struct is_nullable |
| { |
| private: |
| BOOST_STATIC_CONSTANT( T*, var ); |
| public: |
| |
| #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400) |
| #pragma warning(push) |
| #pragma warning(disable:6334) |
| #endif |
| |
| BOOST_STATIC_CONSTANT(bool, value = sizeof( ptr_container_detail::is_nullable( var ) ) |
| == sizeof( type_traits::yes_type ) ); |
| #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400) |
| #pragma warning(pop) |
| #endif |
| |
| }; |
| |
| template< class T > |
| struct remove_nullable |
| { |
| typedef BOOST_DEDUCED_TYPENAME mpl::eval_if< is_nullable<T>, |
| T, |
| mpl::identity<T> >::type |
| type; |
| }; |
| |
| } |
| |
| #endif |