transform_view/detail/at_impl.hpp

0001 /*=============================================================================
0002     Copyright (c) 2001-2011 Joel de Guzman
0003     Copyright (c) 2005-2006 Dan Marsden
0004     Copyright (c) 2018 Kohei Takahashi
0005
0006     Distributed under the Boost Software License, Version 1.0. (See accompanying
0007     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0008 ==============================================================================*/
0009 #if !defined(BOOST_FUSION_AT_IMPL_20061029_1946)
0010 #define BOOST_FUSION_AT_IMPL_20061029_1946
0011
0012 #include <boost/fusion/support/config.hpp>
0013 #include <boost/fusion/sequence/intrinsic/at.hpp>
0014 #include <boost/utility/result_of.hpp>
0015
0016 namespace boost { namespace fusion {
0017     struct transform_view_tag;
0018     struct transform_view2_tag;
0019
0020     namespace extension
0021     {
0022         template<typename Tag>
0023         struct at_impl;
0024
0025         template<>
0026         struct at_impl<transform_view_tag>
0027         {
0028             template<typename Seq, typename N>
0029             struct apply
0030             {
0031                 typedef typename Seq::transform_type F;
0032                 typedef typename result_of::at<typename Seq::sequence_type, N>::type value_type;
0033                 typedef typename boost::result_of<F(value_type)>::type type;
0034
0035                 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
0036                 static type call(Seq& seq)
0037                 {
0038                     return seq.f(boost::fusion::at<N>(seq.seq));
0039                 }
0040             };
0041         };
0042
0043         template<>
0044         struct at_impl<transform_view2_tag>
0045         {
0046             template<typename Seq, typename N>
0047             struct apply
0048             {
0049                 typedef typename Seq::transform_type F;
0050                 typedef typename result_of::at<typename Seq::sequence1_type, N>::type value1_type;
0051                 typedef typename result_of::at<typename Seq::sequence2_type, N>::type value2_type;
0052                 typedef typename boost::result_of<F(value1_type, value2_type)>::type type;
0053
0054                 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
0055                 static type call(Seq& seq)
0056                 {
0057                     return seq.f(boost::fusion::at<N>(seq.seq1), boost::fusion::at<N>(seq.seq2));
0058                 }
0059             };
0060         };
0061     }
0062 }}
0063
0064 #endif