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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_DISTANCE_09172005_0721) | |
8 | #define FUSION_DISTANCE_09172005_0721 | |
9 | ||
10 | #include <boost/fusion/support/config.hpp> | |
11 | #include <boost/fusion/iterator/detail/distance.hpp> | |
12 | #include <boost/fusion/support/category_of.hpp> | |
13 | ||
14 | #include <boost/mpl/int.hpp> | |
15 | #include <boost/mpl/assert.hpp> | |
16 | #include <boost/type_traits/is_same.hpp> | |
17 | ||
18 | #include <boost/fusion/support/tag_of.hpp> | |
19 | ||
20 | namespace boost { namespace fusion | |
21 | { | |
22 | struct random_access_traversal_tag; | |
23 | ||
24 | // Special tags: | |
25 | struct iterator_facade_tag; // iterator facade tag | |
26 | struct boost_array_iterator_tag; // boost::array iterator tag | |
27 | struct mpl_iterator_tag; // mpl sequence iterator tag | |
28 | struct std_pair_iterator_tag; // std::pair iterator tag | |
29 | ||
30 | namespace extension | |
31 | { | |
32 | template <typename Tag> | |
33 | struct distance_impl | |
34 | { | |
35 | // default implementation | |
36 | template <typename First, typename Last> | |
37 | struct apply : distance_detail::linear_distance<First, Last> | |
38 | {}; | |
39 | }; | |
40 | ||
41 | template <> | |
42 | struct distance_impl<iterator_facade_tag> | |
43 | { | |
44 | template <typename First, typename Last> | |
45 | struct apply : First::template distance<First, Last> {}; | |
46 | }; | |
47 | ||
48 | template <> | |
49 | struct distance_impl<boost_array_iterator_tag>; | |
50 | ||
51 | template <> | |
52 | struct distance_impl<mpl_iterator_tag>; | |
53 | ||
54 | template <> | |
55 | struct distance_impl<std_pair_iterator_tag>; | |
56 | } | |
57 | ||
58 | namespace result_of | |
59 | { | |
60 | template <typename First, typename Last> | |
61 | struct distance | |
62 | : extension::distance_impl<typename detail::tag_of<First>::type>:: | |
63 | template apply<First, Last> | |
64 | { | |
65 | typedef typename extension::distance_impl<typename detail::tag_of<First>::type>:: | |
66 | template apply<First, Last>::type distance_application; | |
67 | BOOST_STATIC_CONSTANT(int, value = distance_application::value); | |
68 | }; | |
69 | } | |
70 | ||
71 | template <typename First, typename Last> | |
72 | BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED | |
73 | inline typename result_of::distance<First, Last>::type | |
74 | distance(First const& a, Last const& b) | |
75 | { | |
76 | return result_of::distance<First, Last>::call(a,b); | |
77 | } | |
78 | }} | |
79 | ||
80 | #endif |