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_VALUE_OF_05052005_1126)
8 #define FUSION_VALUE_OF_05052005_1126
9 
10 #include <boost/fusion/support/config.hpp>
11 #include <boost/fusion/support/iterator_base.hpp>
12 #include <boost/fusion/support/tag_of.hpp>
13 
14 namespace boost { namespace fusion
15 {
16     // Special tags:
17     struct iterator_facade_tag; // iterator facade tag
18     struct boost_array_iterator_tag; // boost::array iterator tag
19     struct mpl_iterator_tag; // mpl sequence iterator tag
20     struct std_pair_iterator_tag; // std::pair iterator tag
21 
22     namespace extension
23     {
24         template <typename Tag>
25         struct value_of_impl
26         {
27             template <typename Iterator>
28             struct apply {};
29         };
30 
31         template <>
32         struct value_of_impl<iterator_facade_tag>
33         {
34             template <typename Iterator>
35             struct apply : Iterator::template value_of<Iterator> {};
36         };
37 
38         template <>
39         struct value_of_impl<boost_array_iterator_tag>;
40 
41         template <>
42         struct value_of_impl<mpl_iterator_tag>;
43 
44         template <>
45         struct value_of_impl<std_pair_iterator_tag>;
46     }
47 
48     namespace result_of
49     {
50         template <typename Iterator>
51         struct value_of
52             : extension::value_of_impl<typename detail::tag_of<Iterator>::type>::
53                 template apply<Iterator>
54         {};
55     }
56 }}
57 
58 #endif
59