1 /*=============================================================================
2     Copyright (c) 2001-2011 Joel de Guzman
3     Copyright (c) 2006 Dan Marsden
4 
5     Distributed under the Boost Software License, Version 1.0. (See accompanying
6     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
7 ==============================================================================*/
8 #if !defined(FUSION_END_IMPL_20060123_2208)
9 #define FUSION_END_IMPL_20060123_2208
10 
11 #include <boost/fusion/support/config.hpp>
12 #include <boost/fusion/view/zip_view/zip_view_iterator_fwd.hpp>
13 #include <boost/fusion/sequence/intrinsic/end.hpp>
14 #include <boost/fusion/sequence/intrinsic/begin.hpp>
15 #include <boost/fusion/sequence/intrinsic/size.hpp>
16 #include <boost/fusion/sequence/intrinsic/front.hpp>
17 #include <boost/fusion/iterator/advance.hpp>
18 #include <boost/fusion/algorithm/transformation/transform.hpp>
19 #include <boost/type_traits/remove_reference.hpp>
20 #include <boost/type_traits/is_reference.hpp>
21 #include <boost/mpl/assert.hpp>
22 #include <boost/mpl/min.hpp>
23 
24 #include <boost/mpl/eval_if.hpp>
25 #include <boost/mpl/identity.hpp>
26 #include <boost/type_traits/is_same.hpp>
27 
28 namespace boost { namespace fusion {
29 
30     struct zip_view_tag;
31 
32     namespace detail
33     {
34         template<typename SeqRef, typename M>
35         struct get_endpoint
36         {
37             typedef typename remove_reference<SeqRef>::type Seq;
38             typedef typename result_of::begin<Seq>::type begin;
39             typedef typename result_of::advance<begin, M>::type type;
40         };
41 
42         template<typename M>
43         struct endpoints
44         {
45             template<typename T>
46             struct result;
47 
48             template<typename M1, typename SeqRef>
49             struct result<endpoints<M1>(SeqRef)>
50                 : mpl::eval_if<is_same<SeqRef, unused_type const&>,
51                                mpl::identity<unused_type>,
52                                get_endpoint<SeqRef, M> >
53             {
54                 BOOST_MPL_ASSERT((is_reference<SeqRef>));
55             };
56 
57             template<typename Seq>
58             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
59             typename result<endpoints(Seq&)>::type
operator ()boost::fusion::detail::endpoints60             operator()(Seq& seq) const
61             {
62                 return fusion::advance<M>(fusion::begin(seq));
63             }
64 
65             template<typename Seq>
66             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
67             typename result<endpoints(Seq const&)>::type
operator ()boost::fusion::detail::endpoints68             operator()(Seq const& seq) const
69             {
70                 return fusion::advance<M>(fusion::begin(seq));
71             }
72 
73             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
operator ()boost::fusion::detail::endpoints74             unused_type operator()(unused_type const&) const
75             {
76                 return unused_type();
77             }
78         };
79     }
80 
81     namespace extension
82     {
83         template<typename Tag>
84         struct end_impl;
85 
86         template<>
87         struct end_impl<zip_view_tag>
88         {
89             template<typename Sequence>
90             struct apply
91             {
92                 typedef zip_view_iterator<
93                     typename result_of::transform<typename Sequence::sequences, detail::endpoints<typename Sequence::size> >::type,
94                     typename Sequence::category> type;
95 
96                 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
97                 static type
callboost::fusion::extension::end_impl::apply98                 call(Sequence& sequence)
99                 {
100                     return type(
101                         fusion::transform(sequence.sequences_, detail::endpoints<typename Sequence::size>()));
102                 }
103             };
104         };
105     }
106 }}
107 
108 #endif
109