text: /*=============================================================================
      Copyright (c) 2001-2013 Joel de Guzman
      Copyright (c) 2018 Kohei Takahashi
  
      Distributed under the Boost Software License, Version 1.0. (See accompanying
      file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  ==============================================================================*/
  #if !defined(BOOST_FUSION_MAP_DETAIL_VALUE_AT_KEY_IMPL_02042013_0821)
  #define BOOST_FUSION_MAP_DETAIL_VALUE_AT_KEY_IMPL_02042013_0821
  
  #include <boost/fusion/support/config.hpp>
  #include <boost/utility/declval.hpp>
  
  namespace boost { namespace fusion
  {
      struct map_tag;
  
      namespace extension
      {
          template <typename Tag>
          struct value_at_key_impl;
  
          template <>
          struct value_at_key_impl<map_tag>
          {
              template <typename Sequence, typename Key>
              struct apply
              {
                  typedef typename BOOST_FUSION_IDENTIFIED_TYPE((
                      boost::declval<Sequence>().get_val(mpl::identity<Key>())
                  )) type;
              };
          };
      }
  }}
  
  #endif
  