/*============================================================================= | |
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 | |