boost/fusion/view/joint_view/detail/begin_impl.hpp

   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_BEGIN_IMPL_07162005_0115)
   8 #define FUSION_BEGIN_IMPL_07162005_0115
   9
  10 #include <boost/fusion/support/config.hpp>
  11 #include <boost/fusion/iterator/equal_to.hpp>
  12 #include <boost/mpl/if.hpp>
  13
  14 namespace boost { namespace fusion
  15 {
  16     struct joint_view_tag;
  17
  18     template <typename Category, typename First, typename Last, typename Concat>
  19     struct joint_view_iterator;
  20
  21     namespace extension
  22     {
  23         template <typename Tag>
  24         struct begin_impl;
  25
  26         template <>
  27         struct begin_impl<joint_view_tag>
  28         {
  29             template <typename Sequence>
  30             struct apply
  31             {
  32                 typedef typename Sequence::first_type first_type;
  33                 typedef typename Sequence::last_type last_type;
  34                 typedef typename Sequence::concat_type concat_type;
  35                 typedef typename Sequence::category category;
  36                 typedef result_of::equal_to<first_type, last_type> equal_to;
  37
  38                 typedef typename
  39                     mpl::if_<
  40                         equal_to
  41                       , concat_type
  42                       , joint_view_iterator<category, first_type, last_type, concat_type>
  43                     >::type
  44                 type;
  45
  46                 BOOST_FUSION_GPU_ENABLED
  47                 static type
  48                 call(Sequence& s, mpl::true_)
  49                 {
  50                     return s.concat();
  51                 }
  52
  53                 BOOST_FUSION_GPU_ENABLED
  54                 static type
  55                 call(Sequence& s, mpl::false_)
  56                 {
  57                     return type(s.first(), s.concat());
  58                 }
  59
  60                 BOOST_FUSION_GPU_ENABLED
  61                 static type
  62                 call(Sequence& s)
  63                 {
  64                     return call(s, equal_to());
  65                 }
  66             };
  67         };
  68     }
  69 }}
  70
  71 #endif