ceph/src/boost/libs/fusion/include/boost/fusion/container/map/detail/value_at_impl.hpp

   1 /*=============================================================================
   2     Copyright (c) 2001-2013 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_MAP_DETAIL_VALUE_AT_IMPL_02042013_0821)
   8 #define BOOST_FUSION_MAP_DETAIL_VALUE_AT_IMPL_02042013_0821
   9
  10 #include <boost/fusion/support/config.hpp>
  11 #include <boost/mpl/at.hpp>
  12 #include <boost/utility/declval.hpp>
  13
  14 namespace boost { namespace fusion
  15 {
  16     struct map_tag;
  17
  18     namespace extension
  19     {
  20         template <typename Tag>
  21         struct value_at_impl;
  22
  23         template <>
  24         struct value_at_impl<map_tag>
  25         {
  26             template <typename Sequence, typename N>
  27             struct apply
  28             {
  29                 typedef mpl::int_<N::value> index;
  30                 typedef
  31                     decltype(boost::declval<Sequence>().get_val(index()))
  32                 type;
  33             };
  34         };
  35     }
  36 }}
  37
  38 #endif
  39