reverse_view/detail/distance_impl.hpp

0001 /*=============================================================================
0002     Copyright (c) 2001-2011 Joel de Guzman
0003     Copyright (c) 2005-2006 Dan Marsden
0004
0005     Distributed under the Boost Software License, Version 1.0. (See accompanying
0006     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0007 ==============================================================================*/
0008 #if !defined(FUSION_DISTANCE_IMPL_14122005_2104)
0009 #define FUSION_DISTANCE_IMPL_14122005_2104
0010
0011 #include <boost/fusion/support/config.hpp>
0012 #include <boost/fusion/iterator/distance.hpp>
0013
0014 namespace boost { namespace fusion {
0015
0016     struct reverse_view_iterator_tag;
0017
0018     template <typename Iterator>
0019     struct reverse_view_iterator;
0020
0021     namespace extension
0022     {
0023         template<typename Tag>
0024         struct distance_impl;
0025
0026         template<>
0027         struct distance_impl<reverse_view_iterator_tag>
0028         {
0029             template<typename First, typename Last>
0030             struct apply
0031             {
0032                 typedef typename First::first_type first_type;
0033                 typedef typename Last::first_type last_type;
0034                 typedef typename result_of::distance<last_type, first_type>::type type;
0035
0036                 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
0037                 static type
0038                 call(First const& first, Last const& last)
0039                 {
0040                     return boost::fusion::distance(last.first, first.first);
0041                 }
0042             };
0043         };
0044     }
0045 }}
0046
0047 #endif