// // 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