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_ITERATOR_FACADE_09252006_1011)
8 #define FUSION_ITERATOR_FACADE_09252006_1011
9 
10 #include <boost/fusion/support/config.hpp>
11 #include <boost/fusion/support/iterator_base.hpp>
12 #include <boost/fusion/iterator/detail/advance.hpp>
13 #include <boost/fusion/iterator/detail/distance.hpp>
14 #include <boost/fusion/support/category_of.hpp>
15 #include <boost/type_traits/is_same.hpp>
16 #include <boost/mpl/assert.hpp>
17 #include <boost/mpl/if.hpp>
18 
19 namespace boost { namespace fusion
20 {
21     struct iterator_facade_tag;
22 
23     template <typename Derived, typename Category>
24     struct iterator_facade : iterator_base<Derived>
25     {
26         typedef iterator_facade_tag fusion_tag;
27         typedef Derived derived_type;
28         typedef Category category;
29 
30         // default implementation
31         template <typename I1, typename I2>
32         struct equal_to // default implementation
33             : is_same<
34                 typename I1::derived_type
35               , typename I2::derived_type
36             >
37         {};
38 
39         // default implementation
40         template <typename Iterator, typename N>
41         struct advance :
42             mpl::if_c<
43                 (N::value > 0)
44               , advance_detail::forward<Iterator, N::value>
45               , advance_detail::backward<Iterator, N::value>
46             >::type
47         {
48             BOOST_MPL_ASSERT_NOT((traits::is_random_access<Iterator>));
49         };
50 
51         // default implementation
52         template <typename First, typename Last>
53         struct distance :
54             distance_detail::linear_distance<First, Last>
55         {};
56     };
57 }}
58 
59 #ifdef BOOST_FUSION_WORKAROUND_FOR_LWG_2408
60 namespace std
61 {
62     template <typename Derived, typename Category>
63     struct iterator_traits< ::boost::fusion::iterator_facade<Derived, Category> >
64     { };
65 }
66 #endif
67 
68 #endif
69