Chris@16: //
Chris@16: // Boost.Pointer Container
Chris@16: //
Chris@16: //  Copyright Thorsten Ottosen 2003-2005. Use, modification and
Chris@16: //  distribution is subject to the Boost Software License, Version
Chris@16: //  1.0. (See accompanying file LICENSE_1_0.txt or copy at
Chris@16: //  http://www.boost.org/LICENSE_1_0.txt)
Chris@16: //
Chris@16: // For more information, see http://www.boost.org/libs/ptr_container/
Chris@16: //
Chris@16: 
Chris@16: 
Chris@16: #ifndef BOOST_INDIRECT_CONTAINER_NULLABLE_HPP
Chris@16: #define BOOST_INDIRECT_CONTAINER_NULLABLE_HPP
Chris@16: 
Chris@16: #if defined(_MSC_VER) && (_MSC_VER >= 1200)
Chris@16: # pragma once
Chris@16: #endif
Chris@16: 
Chris@16: #include <boost/type_traits/detail/yes_no_type.hpp>
Chris@16: #include <boost/mpl/eval_if.hpp>
Chris@16: #include <boost/mpl/identity.hpp>
Chris@16: #include <boost/config.hpp>
Chris@16: 
Chris@16: namespace boost
Chris@16: {
Chris@16:     
Chris@16:     template< class T >
Chris@16:     struct nullable
Chris@16:     {
Chris@16:         typedef T type;
Chris@16:     };   
Chris@16: 
Chris@16:     namespace ptr_container_detail
Chris@16:     {
Chris@16:         template< class T >
Chris@16:         type_traits::yes_type is_nullable( const nullable<T>* );
Chris@16: 
Chris@16:         type_traits::no_type is_nullable( ... );        
Chris@16:     }
Chris@16: 
Chris@16:     template< class T >
Chris@16:     struct is_nullable
Chris@16:     {
Chris@16:     private:
Chris@16:             BOOST_STATIC_CONSTANT( T*, var );
Chris@16:     public:
Chris@16: 
Chris@16: #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)  
Chris@16: #pragma warning(push)  
Chris@16: #pragma warning(disable:6334)  
Chris@16: #endif  
Chris@16: 
Chris@16:             BOOST_STATIC_CONSTANT(bool, value = sizeof( ptr_container_detail::is_nullable( var ) ) 
Chris@16:                                                 == sizeof( type_traits::yes_type ) );
Chris@16: #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)  
Chris@16: #pragma warning(pop)  
Chris@16: #endif  
Chris@16:             
Chris@16:     };
Chris@16:     
Chris@16:     template< class T >
Chris@16:     struct remove_nullable
Chris@16:     {
Chris@16:         typedef BOOST_DEDUCED_TYPENAME mpl::eval_if< is_nullable<T>,
Chris@16:                                                       T,
Chris@16:                                             mpl::identity<T> >::type
Chris@16:             type;
Chris@16:     };
Chris@16: 
Chris@16: }
Chris@16: 
Chris@16: #endif