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_DEREF_05042005_1019)
8 #define FUSION_DEREF_05042005_1019
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 deref_impl
26         {
27             template <typename Iterator>
28             struct apply {};
29         };
30 
31         template <>
32         struct deref_impl<iterator_facade_tag>
33         {
34             template <typename Iterator>
35             struct apply : Iterator::template deref<Iterator> {};
36        };
37 
38         template <>
39         struct deref_impl<boost_array_iterator_tag>;
40 
41         template <>
42         struct deref_impl<mpl_iterator_tag>;
43 
44         template <>
45         struct deref_impl<std_pair_iterator_tag>;
46     }
47 
48     namespace result_of
49     {
50         template <typename Iterator>
51         struct deref
52             : extension::deref_impl<typename detail::tag_of<Iterator>::type>::
53                 template apply<Iterator>
54         {};
55     }
56 
57     template <typename Iterator>
58     BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
59     inline typename result_of::deref<Iterator>::type
deref(Iterator const & i)60     deref(Iterator const& i)
61     {
62         typedef result_of::deref<Iterator> deref_meta;
63         return deref_meta::call(i);
64     }
65 
66     template <typename Iterator>
67     BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
68     inline typename result_of::deref<Iterator>::type
operator *(iterator_base<Iterator> const & i)69     operator*(iterator_base<Iterator> const& i)
70     {
71         return fusion::deref(i.cast());
72     }
73 }}
74 
75 #endif
76