boost/fusion/view/zip_view/zip_view.hpp

   1 /*=============================================================================
   2     Copyright (c) 2001-2006 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_ZIP_VIEW_23012006_0813)
   9 #define FUSION_ZIP_VIEW_23012006_0813
  10
  11 #include <boost/fusion/support/sequence_base.hpp>
  12 #include <boost/fusion/support/unused.hpp>
  13 #include <boost/fusion/iterator/equal_to.hpp>
  14 #include <boost/fusion/view/detail/strictest_traversal.hpp>
  15 #include <boost/fusion/view/zip_view/detail/begin_impl.hpp>
  16 #include <boost/fusion/view/zip_view/detail/end_impl.hpp>
  17 #include <boost/fusion/view/zip_view/detail/size_impl.hpp>
  18 #include <boost/fusion/view/zip_view/detail/at_impl.hpp>
  19 #include <boost/fusion/view/zip_view/detail/value_at_impl.hpp>
  20 #include <boost/fusion/container/vector/convert.hpp>
  21 #include <boost/fusion/algorithm/query/find_if.hpp>
  22 #include <boost/fusion/sequence/intrinsic/end.hpp>
  23 #include <boost/fusion/sequence/intrinsic/size.hpp>
  24 #include <boost/fusion/mpl.hpp>
  25 #include <boost/fusion/algorithm/transformation/remove.hpp>
  26
  27 #include <boost/mpl/assert.hpp>
  28 #include <boost/mpl/not.hpp>
  29 #include <boost/mpl/placeholders.hpp>
  30 #include <boost/mpl/transform_view.hpp>
  31 #include <boost/mpl/at.hpp>
  32 #include <boost/mpl/find_if.hpp>
  33 #include <boost/mpl/equal_to.hpp>
  34 #include <boost/mpl/bool.hpp>
  35 #include <boost/mpl/eval_if.hpp>
  36
  37 #include <boost/type_traits/remove_reference.hpp>
  38 #include <boost/type_traits/is_reference.hpp>
  39
  40 namespace boost { namespace fusion {
  41
  42     namespace detail
  43     {
  44         template<typename Sequences>
  45         struct all_references
  46             : fusion::result_of::equal_to<typename fusion::result_of::find_if<Sequences, mpl::not_<is_reference<mpl::_> > >::type, typename fusion::result_of::end<Sequences>::type>
  47         {};
  48
  49         struct seq_ref_size
  50         {
  51             template<typename Params>
  52             struct result;
  53
  54             template<typename Seq>
  55             struct result<seq_ref_size(Seq)>
  56             {
  57                 static int const high_int = static_cast<int>(
  58                     (static_cast<unsigned>(~0) >> 1) - 1);
  59
  60                 typedef typename remove_reference<Seq>::type SeqClass;
  61
  62                 typedef typename mpl::eval_if<
  63                     traits::is_forward<SeqClass>,
  64                     result_of::size<SeqClass>,
  65                     mpl::int_<high_int> >::type type;
  66             };
  67         };
  68
  69         struct poly_min
  70         {
  71             template<typename T>
  72             struct result;
  73
  74             template<typename Lhs, typename Rhs>
  75             struct result<poly_min(Lhs, Rhs)>
  76             {
  77                 typedef typename remove_reference<Lhs>::type lhs;
  78                 typedef typename remove_reference<Rhs>::type rhs;
  79                 typedef typename mpl::min<lhs, rhs>::type type;
  80             };
  81         };
  82
  83         template<typename Sequences>
  84         struct min_size
  85         {
  86             typedef typename result_of::transform<Sequences, detail::seq_ref_size>::type sizes;
  87             typedef typename result_of::fold<sizes, typename result_of::front<sizes>::type, detail::poly_min>::type type;
  88         };
  89     }
  90
  91     struct zip_view_tag;
  92     struct fusion_sequence_tag;
  93
  94     template<typename Sequences>
  95     struct zip_view : sequence_base< zip_view<Sequences> >
  96     {
  97         typedef typename result_of::remove<Sequences, unused_type const&>::type real_sequences;
  98         BOOST_MPL_ASSERT((detail::all_references<Sequences>));
  99         typedef typename detail::strictest_traversal<real_sequences>::type category;
 100         typedef zip_view_tag fusion_tag;
 101         typedef fusion_sequence_tag tag; // this gets picked up by MPL
 102         typedef mpl::true_ is_view;
 103         typedef typename fusion::result_of::as_vector<Sequences>::type sequences;
 104         typedef typename detail::min_size<real_sequences>::type size;
 105
 106         zip_view(
 107             const Sequences& seqs)
 108             : sequences_(seqs)
 109         {};
 110
 111         sequences sequences_;
 112     };
 113 }}
 114
 115 #endif