| 1 | // |
|---|---|
| 2 | // Boost.Pointer Container |
| 3 | // |
| 4 | // Copyright Thorsten Ottosen 2003-2005. Use, modification and |
| 5 | // distribution is subject to the Boost Software License, Version |
| 6 | // 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
| 7 | // http://www.boost.org/LICENSE_1_0.txt) |
| 8 | // |
| 9 | // For more information, see http://www.boost.org/libs/ptr_container/ |
| 10 | // |
| 11 | |
| 12 | |
| 13 | #ifndef BOOST_INDIRECT_CONTAINER_NULLABLE_HPP |
| 14 | #define BOOST_INDIRECT_CONTAINER_NULLABLE_HPP |
| 15 | |
| 16 | #if defined(_MSC_VER) && (_MSC_VER >= 1200) |
| 17 | # pragma once |
| 18 | #endif |
| 19 | |
| 20 | #include <boost/type_traits/detail/yes_no_type.hpp> |
| 21 | #include <boost/mpl/eval_if.hpp> |
| 22 | #include <boost/mpl/identity.hpp> |
| 23 | #include <boost/config.hpp> |
| 24 | |
| 25 | namespace boost |
| 26 | { |
| 27 | |
| 28 | template< class T > |
| 29 | struct nullable |
| 30 | { |
| 31 | typedef T type; |
| 32 | }; |
| 33 | |
| 34 | namespace ptr_container_detail |
| 35 | { |
| 36 | template< class T > |
| 37 | type_traits::yes_type is_nullable( const nullable<T>* ); |
| 38 | |
| 39 | type_traits::no_type is_nullable( ... ); |
| 40 | } |
| 41 | |
| 42 | template< class T > |
| 43 | struct is_nullable |
| 44 | { |
| 45 | private: |
| 46 | BOOST_STATIC_CONSTANT( T*, var ); |
| 47 | public: |
| 48 | |
| 49 | #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400) |
| 50 | #pragma warning(push) |
| 51 | #pragma warning(disable:6334) |
| 52 | #endif |
| 53 | |
| 54 | BOOST_STATIC_CONSTANT(bool, value = sizeof( ptr_container_detail::is_nullable( var ) ) |
| 55 | == sizeof( type_traits::yes_type ) ); |
| 56 | #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400) |
| 57 | #pragma warning(pop) |
| 58 | #endif |
| 59 | |
| 60 | }; |
| 61 | |
| 62 | template< class T > |
| 63 | struct remove_nullable |
| 64 | { |
| 65 | typedef BOOST_DEDUCED_TYPENAME mpl::eval_if< is_nullable<T>, |
| 66 | T, |
| 67 | mpl::identity<T> >::type |
| 68 | type; |
| 69 | }; |
| 70 | |
| 71 | } |
| 72 | |
| 73 | #endif |
| 74 |