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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_AT_05042005_0722) | |
8 | #define FUSION_AT_05042005_0722 | |
9 | ||
10 | #include <boost/fusion/support/config.hpp> | |
11 | #include <boost/mpl/int.hpp> | |
12 | #include <boost/mpl/if.hpp> | |
13 | #include <boost/mpl/or.hpp> | |
14 | #include <boost/mpl/less.hpp> | |
15 | #include <boost/mpl/empty_base.hpp> | |
16 | #include <boost/type_traits/is_const.hpp> | |
17 | #include <boost/fusion/sequence/intrinsic_fwd.hpp> | |
18 | #include <boost/fusion/support/tag_of.hpp> | |
19 | #include <boost/fusion/support/category_of.hpp> | |
20 | ||
21 | namespace boost { namespace fusion | |
22 | { | |
23 | // Special tags: | |
24 | struct sequence_facade_tag; | |
25 | struct boost_tuple_tag; // boost::tuples::tuple tag | |
26 | struct boost_array_tag; // boost::array tag | |
27 | struct mpl_sequence_tag; // mpl sequence tag | |
28 | struct std_pair_tag; // std::pair tag | |
29 | struct std_tuple_tag; // std::tuple tag | |
30 | ||
31 | namespace extension | |
32 | { | |
33 | template <typename Tag> | |
34 | struct at_impl | |
35 | { | |
36 | template <typename Sequence, typename N> | |
37 | struct apply; | |
38 | }; | |
39 | ||
40 | template <> | |
41 | struct at_impl<sequence_facade_tag> | |
42 | { | |
43 | template <typename Sequence, typename N> | |
44 | struct apply : Sequence::template at<Sequence, N> {}; | |
45 | }; | |
46 | ||
47 | template <> | |
48 | struct at_impl<boost_tuple_tag>; | |
49 | ||
50 | template <> | |
51 | struct at_impl<boost_array_tag>; | |
52 | ||
53 | template <> | |
54 | struct at_impl<mpl_sequence_tag>; | |
55 | ||
56 | template <> | |
57 | struct at_impl<std_pair_tag>; | |
58 | ||
59 | template <> | |
60 | struct at_impl<std_tuple_tag>; | |
61 | } | |
62 | ||
63 | namespace detail | |
64 | { | |
65 | template <typename Sequence, typename N, typename Tag> | |
66 | struct at_impl | |
67 | : mpl::if_< | |
68 | mpl::or_< | |
69 | mpl::less<N, typename extension::size_impl<Tag>::template apply<Sequence>::type> | |
70 | , traits::is_unbounded<Sequence> | |
71 | > | |
72 | , typename extension::at_impl<Tag>::template apply<Sequence, N> | |
73 | , mpl::empty_base | |
74 | >::type | |
75 | {}; | |
76 | } | |
77 | ||
78 | namespace result_of | |
79 | { | |
80 | template <typename Sequence, typename N> | |
81 | struct at | |
82 | : detail::at_impl<Sequence, N, typename detail::tag_of<Sequence>::type> | |
83 | {}; | |
84 | ||
85 | template <typename Sequence, int N> | |
86 | struct at_c | |
87 | : at<Sequence, mpl::int_<N> > | |
88 | {}; | |
89 | } | |
90 | ||
91 | ||
92 | template <typename N, typename Sequence> | |
93 | BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED | |
94 | inline typename | |
95 | lazy_disable_if< | |
96 | is_const<Sequence> | |
97 | , result_of::at<Sequence, N> | |
98 | >::type | |
99 | at(Sequence& seq) | |
100 | { | |
101 | return result_of::at<Sequence, N>::call(seq); | |
102 | } | |
103 | ||
104 | template <typename N, typename Sequence> | |
105 | BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED | |
106 | inline typename result_of::at<Sequence const, N>::type | |
107 | at(Sequence const& seq) | |
108 | { | |
109 | return result_of::at<Sequence const, N>::call(seq); | |
110 | } | |
111 | ||
112 | template <int N, typename Sequence> | |
113 | BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED | |
114 | inline typename | |
115 | lazy_disable_if< | |
116 | is_const<Sequence> | |
117 | , result_of::at_c<Sequence, N> | |
118 | >::type | |
119 | at_c(Sequence& seq) | |
120 | { | |
121 | return fusion::at<mpl::int_<N> >(seq); | |
122 | } | |
123 | ||
124 | template <int N, typename Sequence> | |
125 | BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED | |
126 | inline typename result_of::at_c<Sequence const, N>::type | |
127 | at_c(Sequence const& seq) | |
128 | { | |
129 | return fusion::at<mpl::int_<N> >(seq); | |
130 | } | |
131 | }} | |
132 | ||
133 | #endif | |
134 |