ceph/src/boost/libs/fusion/include/boost/fusion/view/zip_view/detail/deref_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_DEREF_IMPL_20061024_1959)
   9 #define FUSION_DEREF_IMPL_20061024_1959
  10
  11 #include <boost/fusion/support/config.hpp>
  12 #include <boost/fusion/container/vector.hpp>
  13 #include <boost/fusion/iterator/deref.hpp>
  14 #include <boost/fusion/algorithm/transformation/transform.hpp>
  15 #include <boost/fusion/container/vector/convert.hpp>
  16 #include <boost/fusion/support/unused.hpp>
  17 #include <boost/mpl/eval_if.hpp>
  18 #include <boost/mpl/identity.hpp>
  19 #include <boost/type_traits/is_same.hpp>
  20 #include <boost/type_traits/remove_reference.hpp>
  21 #include <boost/type_traits/remove_const.hpp>
  22
  23 namespace boost { namespace fusion {
  24
  25     struct zip_view_iterator_tag;
  26
  27     namespace detail
  28     {
  29         struct poly_deref
  30         {
  31             template<typename Sig>
  32             struct result;
  33
  34             template<typename It>
  35             struct result<poly_deref(It)>
  36             {
  37                 typedef typename remove_const<
  38                     typename remove_reference<It>::type>::type it;
  39
  40                 typedef typename mpl::eval_if<is_same<it, unused_type>,
  41                     mpl::identity<unused_type>,
  42                     result_of::deref<it> >::type type;
  43             };
  44
  45             template<typename It>
  46             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
  47             typename result<poly_deref(It)>::type
  48             operator()(const It& it) const
  49             {
  50                 return fusion::deref(it);
  51             }
  52
  53             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
  54             unused_type operator()(unused_type const&) const
  55             {
  56                 return unused_type();
  57             }
  58         };
  59     }
  60
  61     namespace extension
  62     {
  63         template<typename Tag>
  64         struct deref_impl;
  65
  66         template<>
  67         struct deref_impl<zip_view_iterator_tag>
  68         {
  69             template<typename It>
  70             struct apply
  71             {
  72                 typedef typename result_of::as_vector<
  73                     typename result_of::transform<typename It::iterators, detail::poly_deref>::type>::type type;
  74
  75                 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
  76                 static type
  77                 call(It const& it)
  78                 {
  79                     return type(
  80                         fusion::transform(it.iterators_, detail::poly_deref()));
  81                 }
  82             };
  83         };
  84     }
  85 }}
  86
  87 #endif