deps/boost_1_63_0/boost/fusion/view/zip_view/detail/end_impl.hpp

   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
  60             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
  68             operator()(Seq const& seq) const
  69             {
  70                 return fusion::advance<M>(fusion::begin(seq));
  71             }
  72
  73             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
  74             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
  98                 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