joint_view/detail/next_impl.hpp

0001 /*=============================================================================
0002     Copyright (c) 2001-2011 Joel de Guzman
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 #if !defined(FUSION_NEXT_IMPL_07162005_0136)
0008 #define FUSION_NEXT_IMPL_07162005_0136
0009
0010 #include <boost/fusion/support/config.hpp>
0011 #include <boost/fusion/iterator/next.hpp>
0012 #include <boost/fusion/iterator/equal_to.hpp>
0013 #include <boost/mpl/if.hpp>
0014
0015 namespace boost { namespace fusion
0016 {
0017     struct joint_view_iterator_tag;
0018
0019     template <typename Category, typename First, typename Last, typename Concat>
0020     struct joint_view_iterator;
0021
0022     namespace extension
0023     {
0024         template <typename Tag>
0025         struct next_impl;
0026
0027         template <>
0028         struct next_impl<joint_view_iterator_tag>
0029         {
0030             template <typename Iterator>
0031             struct apply
0032             {
0033                 typedef typename Iterator::first_type first_type;
0034                 typedef typename Iterator::last_type last_type;
0035                 typedef typename Iterator::concat_type concat_type;
0036                 typedef typename Iterator::category category;
0037                 typedef typename result_of::next<first_type>::type next_type;
0038                 typedef result_of::equal_to<next_type, last_type> equal_to;
0039
0040                 typedef typename
0041                     mpl::if_<
0042                         equal_to
0043                       , concat_type
0044                       , joint_view_iterator<category, next_type, last_type, concat_type>
0045                     >::type
0046                 type;
0047
0048                 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
0049                 static type
0050                 call(Iterator const& i, mpl::true_)
0051                 {
0052                     return i.concat;
0053                 }
0054
0055                 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
0056                 static type
0057                 call(Iterator const& i, mpl::false_)
0058                 {
0059                     return type(fusion::next(i.first), i.concat);
0060                 }
0061
0062                 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
0063                 static type
0064                 call(Iterator const& i)
0065                 {
0066                     return call(i, equal_to());
0067                 }
0068             };
0069         };
0070     }
0071 }}
0072
0073 #endif
0074
0075