1 /*=============================================================================
2     Copyright (c) 2001-2006 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_PRIOR_05042005_1144)
8 #define FUSION_PRIOR_05042005_1144
9 
10 #include <boost/fusion/support/tag_of.hpp>
11 
12 namespace boost { namespace fusion
13 {
14     // Special tags:
15     struct iterator_facade_tag; // iterator facade tag
16     struct boost_array_iterator_tag; // boost::array iterator tag
17     struct mpl_iterator_tag; // mpl sequence iterator tag
18     struct std_pair_iterator_tag; // std::pair iterator tag
19 
20     namespace extension
21     {
22         template <typename Tag>
23         struct prior_impl
24         {
25             template <typename Iterator>
26             struct apply {};
27         };
28 
29         template <>
30         struct prior_impl<iterator_facade_tag>
31         {
32             template <typename Iterator>
33             struct apply : Iterator::template prior<Iterator> {};
34         };
35 
36         template <>
37         struct prior_impl<boost_array_iterator_tag>;
38 
39         template <>
40         struct prior_impl<mpl_iterator_tag>;
41 
42         template <>
43         struct prior_impl<std_pair_iterator_tag>;
44     }
45 
46     namespace result_of
47     {
48         template <typename Iterator>
49         struct prior
50             : extension::prior_impl<typename detail::tag_of<Iterator>::type>::
51                 template apply<Iterator>
52         {};
53     }
54 
55     template <typename Iterator>
56     typename result_of::prior<Iterator>::type const
prior(Iterator const & i)57     prior(Iterator const& i)
58     {
59         return result_of::prior<Iterator>::call(i);
60     }
61 }}
62 
63 #endif
64