| /*============================================================================= |
| Copyright (c) 2001-2006 Joel de Guzman |
| |
| Distributed under 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) |
| ==============================================================================*/ |
| #if !defined(FUSION_HAS_KEY_09232005_1454) |
| #define FUSION_HAS_KEY_09232005_1454 |
| |
| #include <boost/fusion/support/tag_of.hpp> |
| #include <boost/fusion/iterator/equal_to.hpp> |
| #include <boost/fusion/algorithm/query/find.hpp> |
| #include <boost/fusion/sequence/intrinsic/end.hpp> |
| #include <boost/mpl/not.hpp> |
| |
| namespace boost { namespace fusion |
| { |
| struct void_; |
| |
| // Special tags: |
| struct sequence_facade_tag; |
| struct boost_array_tag; // boost::array tag |
| struct mpl_sequence_tag; // mpl sequence tag |
| struct std_pair_tag; // std::pair tag |
| |
| namespace extension |
| { |
| template <typename Tag> |
| struct has_key_impl |
| { |
| template <typename Seq, typename Key> |
| struct apply |
| : mpl::not_< |
| typename result_of::equal_to< |
| typename result_of::find<Seq, Key>::type |
| , typename result_of::end<Seq>::type |
| >::type |
| >::type |
| {}; |
| }; |
| |
| template <> |
| struct has_key_impl<sequence_facade_tag> |
| { |
| template <typename Sequence, typename Key> |
| struct apply : Sequence::template has_key<Sequence, Key> {}; |
| }; |
| |
| template <> |
| struct has_key_impl<boost_array_tag>; |
| |
| template <> |
| struct has_key_impl<mpl_sequence_tag>; |
| |
| template <> |
| struct has_key_impl<std_pair_tag>; |
| } |
| |
| namespace result_of |
| { |
| template <typename Sequence, typename Key> |
| struct has_key |
| : extension::has_key_impl<typename detail::tag_of<Sequence>::type>:: |
| template apply<Sequence, Key> |
| {}; |
| } |
| |
| template <typename Key, typename Sequence> |
| inline typename result_of::has_key<Sequence, Key>::type |
| has_key(Sequence const& seq) |
| { |
| typedef typename result_of::has_key<Sequence, Key>::type result; |
| return result(); |
| } |
| }} |
| |
| #endif |
| |