nview/detail/value_of_impl.hpp

0001 /*=============================================================================
0002     Copyright (c) 2009 Hartmut Kaiser
0003
0004     Distributed under the Boost Software License, Version 1.0. (See accompanying
0005     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0006 ==============================================================================*/
0007
0008 #if !defined(BOOST_FUSION_VALUE_OF_PRIOR_IMPL_SEP_24_2009_0158PM)
0009 #define BOOST_FUSION_VALUE_OF_PRIOR_IMPL_SEP_24_2009_0158PM
0010
0011 #include <boost/fusion/support/config.hpp>
0012 #include <boost/fusion/iterator/deref.hpp>
0013 #include <boost/fusion/container/vector.hpp>
0014
0015 namespace boost { namespace fusion
0016 {
0017     struct nview_iterator_tag;
0018
0019     template <typename Sequence, typename Pos>
0020     struct nview_iterator;
0021
0022     namespace extension
0023     {
0024         template <typename Tag>
0025         struct value_of_impl;
0026
0027         template <>
0028         struct value_of_impl<nview_iterator_tag>
0029         {
0030             template <typename Iterator>
0031             struct apply
0032             {
0033                 typedef typename Iterator::first_type first_type;
0034                 typedef typename Iterator::sequence_type sequence_type;
0035
0036                 typedef typename result_of::deref<first_type>::type index;
0037                 typedef typename result_of::at<
0038                     typename sequence_type::sequence_type, index>::type type;
0039             };
0040         };
0041     }
0042
0043 }}
0044
0045 #endif