ceph/src/boost/libs/fusion/include/boost/fusion/adapted/std_tuple/detail/at_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(BOOST_FUSION_AT_IMPL_09242011_1744)
   8 #define BOOST_FUSION_AT_IMPL_09242011_1744
   9
  10 #include <boost/fusion/support/config.hpp>
  11 #include <tuple>
  12 #include <utility>
  13 #include <boost/mpl/if.hpp>
  14 #include <boost/fusion/support/detail/access.hpp>
  15 #include <boost/type_traits/remove_const.hpp>
  16
  17 namespace boost { namespace fusion
  18 {
  19     struct std_tuple_tag;
  20
  21     namespace extension
  22     {
  23         template<typename T>
  24         struct at_impl;
  25
  26         template <>
  27         struct at_impl<std_tuple_tag>
  28         {
  29             template <typename Sequence, typename N>
  30             struct apply
  31             {
  32                 typedef typename remove_const<Sequence>::type seq_type;
  33                 typedef typename std::tuple_element<N::value, seq_type>::type element;
  34
  35                 typedef typename
  36                     mpl::if_<
  37                         is_const<Sequence>
  38                       , typename fusion::detail::cref_result<element>::type
  39                       , typename fusion::detail::ref_result<element>::type
  40                     >::type
  41                 type;
  42
  43                 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
  44                 static type
  45                 call(Sequence& seq)
  46                 {
  47                     return std::get<N::value>(seq);
  48                 }
  49             };
  50         };
  51     }
  52 }}
  53
  54 #endif