single_view/detail/value_of_impl.hpp

0001 /*=============================================================================
0002     Copyright (c) 2001-2011 Joel de Guzman
0003     Copyright (c) 2011 Eric Niebler
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(BOOST_FUSION_SINGLE_VIEW_VALUE_OF_IMPL_05052005_0324)
0009 #define BOOST_FUSION_SINGLE_VIEW_VALUE_OF_IMPL_05052005_0324
0010
0011 #include <boost/fusion/support/config.hpp>
0012 #include <boost/mpl/int.hpp>
0013 #include <boost/mpl/assert.hpp>
0014 #include <boost/mpl/equal_to.hpp>
0015
0016 namespace boost { namespace fusion
0017 {
0018     struct single_view_iterator_tag;
0019
0020     namespace extension
0021     {
0022         template <typename Tag>
0023         struct value_of_impl;
0024
0025         template <>
0026         struct value_of_impl<single_view_iterator_tag>
0027         {
0028             template <typename Iterator>
0029             struct apply
0030             {
0031                 BOOST_MPL_ASSERT((mpl::equal_to<typename Iterator::position, mpl::int_<0> >));
0032                 typedef typename Iterator::value_type type;
0033             };
0034         };
0035     }
0036 }}
0037
0038 #endif
0039
0040