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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 |