3rdparty/boost/boost/fusion/view/single_view/detail/at_impl.hpp

   1 /*=============================================================================
   2     Copyright (c) 2011 Eric Niebler
   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
   8 #if !defined(BOOST_FUSION_SINGLE_VIEW_AT_IMPL_JUL_07_2011_1348PM)
   9 #define BOOST_FUSION_SINGLE_VIEW_AT_IMPL_JUL_07_2011_1348PM
  10
  11 #include <boost/fusion/support/config.hpp>
  12 #include <boost/mpl/int.hpp>
  13 #include <boost/mpl/assert.hpp>
  14 #include <boost/mpl/equal_to.hpp>
  15
  16 namespace boost { namespace fusion
  17 {
  18     struct single_view_tag;
  19
  20     namespace extension
  21     {
  22         template<typename Tag>
  23         struct at_impl;
  24
  25         template<>
  26         struct at_impl<single_view_tag>
  27         {
  28             template<typename Sequence, typename N>
  29             struct apply
  30             {
  31                 BOOST_MPL_ASSERT((mpl::equal_to<N, mpl::int_<0> >));
  32                 typedef typename Sequence::value_type type;
  33
  34                 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
  35                 static type
  36                 call(Sequence& seq)
  37                 {
  38                     return seq.val;
  39                 }
  40             };
  41         };
  42     }
  43
  44 }}
  45
  46 #endif