1 | /*============================================================================= |
2 | Copyright (c) 2001-2011 Joel de Guzman |
3 | |
4 | Distributed under the Boost Software License, Version 1.0. (See accompanying |
5 | file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
6 | ==============================================================================*/ |
7 | #if !defined(FUSION_HAS_KEY_09232005_1454) |
8 | #define FUSION_HAS_KEY_09232005_1454 |
9 | |
10 | #include <boost/fusion/support/config.hpp> |
11 | #include <boost/fusion/sequence/intrinsic_fwd.hpp> |
12 | #include <boost/fusion/support/tag_of.hpp> |
13 | #include <boost/fusion/iterator/equal_to.hpp> |
14 | #include <boost/fusion/algorithm/query/find.hpp> |
15 | #include <boost/fusion/sequence/intrinsic/end.hpp> |
16 | #include <boost/mpl/not.hpp> |
17 | |
18 | namespace boost { namespace fusion |
19 | { |
20 | struct void_; |
21 | |
22 | // Special tags: |
23 | struct sequence_facade_tag; |
24 | struct boost_array_tag; // boost::array tag |
25 | struct mpl_sequence_tag; // mpl sequence tag |
26 | struct std_pair_tag; // std::pair tag |
27 | |
28 | namespace extension |
29 | { |
30 | template <typename Tag> |
31 | struct has_key_impl |
32 | { |
33 | template <typename Seq, typename Key> |
34 | struct apply |
35 | : mpl::not_< |
36 | typename result_of::equal_to< |
37 | typename result_of::find<Seq, Key>::type |
38 | , typename result_of::end<Seq>::type |
39 | >::type |
40 | >::type |
41 | {}; |
42 | }; |
43 | |
44 | template <> |
45 | struct has_key_impl<sequence_facade_tag> |
46 | { |
47 | template <typename Sequence, typename Key> |
48 | struct apply : Sequence::template has_key<Sequence, Key> {}; |
49 | }; |
50 | |
51 | template <> |
52 | struct has_key_impl<boost_array_tag>; |
53 | |
54 | template <> |
55 | struct has_key_impl<mpl_sequence_tag>; |
56 | |
57 | template <> |
58 | struct has_key_impl<std_pair_tag>; |
59 | } |
60 | |
61 | namespace result_of |
62 | { |
63 | template <typename Sequence, typename Key> |
64 | struct has_key |
65 | : extension::has_key_impl<typename detail::tag_of<Sequence>::type>:: |
66 | template apply<Sequence, Key> |
67 | {}; |
68 | } |
69 | |
70 | template <typename Key, typename Sequence> |
71 | BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED |
72 | inline typename result_of::has_key<Sequence, Key>::type |
73 | has_key(Sequence const&) |
74 | { |
75 | typedef typename result_of::has_key<Sequence, Key>::type result; |
76 | return result(); |
77 | } |
78 | }} |
79 | |
80 | #endif |
81 | |
82 | |