ceph/src/boost/libs/fusion/include/boost/fusion/view/zip_view/detail/next_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_NEXT_IMPL_20060124_2006)
   9 #define FUSION_NEXT_IMPL_20060124_2006
  10
  11 #include <boost/fusion/support/config.hpp>
  12 #include <boost/fusion/view/zip_view/zip_view_iterator_fwd.hpp>
  13 #include <boost/fusion/iterator/next.hpp>
  14 #include <boost/fusion/algorithm/transformation/transform.hpp>
  15 #include <boost/fusion/support/unused.hpp>
  16 #include <boost/mpl/eval_if.hpp>
  17 #include <boost/mpl/identity.hpp>
  18 #include <boost/type_traits/is_same.hpp>
  19 #include <boost/type_traits/remove_reference.hpp>
  20 #include <boost/type_traits/remove_const.hpp>
  21
  22 namespace boost { namespace fusion {
  23
  24     struct zip_view_iterator_tag;
  25
  26     namespace detail
  27     {
  28         struct poly_next
  29         {
  30             template<typename Sig>
  31             struct result;
  32
  33             template<typename It>
  34             struct result<poly_next(It)>
  35             {
  36                 typedef typename remove_const<
  37                     typename remove_reference<It>::type>::type it;
  38
  39                 typedef typename mpl::eval_if<is_same<it, unused_type>,
  40                     mpl::identity<unused_type>,
  41                     result_of::next<it> >::type type;
  42             };
  43
  44             template<typename It>
  45             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
  46             typename result<poly_next(It)>::type
  47             operator()(const It& it) const
  48             {
  49                 return fusion::next(it);
  50             }
  51
  52             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
  53             unused_type operator()(unused_type const&) const
  54             {
  55                 return unused_type();
  56             }
  57         };
  58     }
  59
  60     namespace extension
  61     {
  62         template<typename Tag>
  63         struct next_impl;
  64
  65         template<>
  66         struct next_impl<zip_view_iterator_tag>
  67         {
  68             template<typename Iterator>
  69             struct apply
  70             {
  71                 typedef fusion::zip_view_iterator<
  72                     typename result_of::transform<typename Iterator::iterators, detail::poly_next>::type,
  73                     typename Iterator::category> type;
  74
  75                 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
  76                 static type
  77                 call(Iterator const& it)
  78                 {
  79                     return type(
  80                         fusion::transform(it.iterators_, detail::poly_next()));
  81                 }
  82             };
  83         };
  84     }
  85 }}
  86
  87 #endif