3rdparty/boost/boost/fusion/container/list/detail/deref_impl.hpp

   1 /*=============================================================================
   2     Copyright (c) 2001-2011 Joel de Guzman
   3     Copyright (c) 2005 Eric Niebler
   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_07172005_0831)
   9 #define FUSION_DEREF_IMPL_07172005_0831
  10
  11 #include <boost/fusion/support/config.hpp>
  12 #include <boost/mpl/eval_if.hpp>
  13 #include <boost/type_traits/is_const.hpp>
  14 #include <boost/type_traits/add_const.hpp>
  15 #include <boost/type_traits/add_reference.hpp>
  16
  17 namespace boost { namespace fusion
  18 {
  19     struct cons_iterator_tag;
  20
  21     namespace extension
  22     {
  23         template <typename Tag>
  24         struct deref_impl;
  25
  26         template <>
  27         struct deref_impl<cons_iterator_tag>
  28         {
  29             template <typename Iterator>
  30             struct apply
  31             {
  32                 typedef typename Iterator::cons_type cons_type;
  33                 typedef typename cons_type::car_type value_type;
  34
  35                 typedef typename mpl::eval_if<
  36                     is_const<cons_type>
  37                   , add_reference<typename add_const<value_type>::type>
  38                   , add_reference<value_type> >::type
  39                 type;
  40
  41                 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
  42                 static type
  43                 call(Iterator const& i)
  44                 {
  45                     return i.cons.car;
  46                 }
  47             };
  48         };
  49     }
  50 }}
  51
  52 #endif
  53
  54