view/zip_view/zip_view.hpp

0001 /*=============================================================================
0002     Copyright (c) 2001-2011 Joel de Guzman
0003     Copyright (c) 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_ZIP_VIEW_23012006_0813)
0009 #define FUSION_ZIP_VIEW_23012006_0813
0010
0011 #include <boost/fusion/support/config.hpp>
0012 #include <boost/fusion/support/sequence_base.hpp>
0013 #include <boost/fusion/support/unused.hpp>
0014 #include <boost/fusion/iterator/equal_to.hpp>
0015 #include <boost/fusion/view/detail/strictest_traversal.hpp>
0016 #include <boost/fusion/view/zip_view/detail/begin_impl.hpp>
0017 #include <boost/fusion/view/zip_view/detail/end_impl.hpp>
0018 #include <boost/fusion/view/zip_view/detail/size_impl.hpp>
0019 #include <boost/fusion/view/zip_view/detail/at_impl.hpp>
0020 #include <boost/fusion/view/zip_view/detail/value_at_impl.hpp>
0021 #include <boost/fusion/container/vector/convert.hpp>
0022 #include <boost/fusion/algorithm/query/find_if.hpp>
0023 #include <boost/fusion/sequence/intrinsic/end.hpp>
0024 #include <boost/fusion/sequence/intrinsic/size.hpp>
0025 #include <boost/fusion/mpl.hpp>
0026 #include <boost/fusion/algorithm/transformation/remove.hpp>
0027
0028 #include <boost/mpl/assert.hpp>
0029 #include <boost/mpl/not.hpp>
0030 #include <boost/mpl/placeholders.hpp>
0031 #include <boost/mpl/transform_view.hpp>
0032 #include <boost/mpl/at.hpp>
0033 #include <boost/mpl/find_if.hpp>
0034 #include <boost/mpl/equal_to.hpp>
0035 #include <boost/mpl/bool.hpp>
0036 #include <boost/mpl/eval_if.hpp>
0037
0038 #include <boost/type_traits/remove_reference.hpp>
0039 #include <boost/type_traits/is_reference.hpp>
0040
0041 #include <boost/config.hpp>
0042
0043 namespace boost { namespace fusion {
0044
0045     namespace detail
0046     {
0047         template<typename Sequences>
0048         struct all_references
0049             : fusion::result_of::equal_to<typename fusion::result_of::find_if<Sequences, mpl::not_<is_reference<mpl::_> > >::type, typename fusion::result_of::end<Sequences>::type>
0050         {};
0051
0052         struct seq_ref_size
0053         {
0054             template<typename Params>
0055             struct result;
0056
0057             template<typename Seq>
0058             struct result<seq_ref_size(Seq)>
0059             {
0060                 static int const high_int = static_cast<int>(
0061                     (static_cast<unsigned>(~0) >> 1) - 1);
0062
0063                 typedef typename remove_reference<Seq>::type SeqClass;
0064
0065                 typedef typename mpl::eval_if<
0066                     traits::is_forward<SeqClass>,
0067                     result_of::size<SeqClass>,
0068                     mpl::int_<high_int> >::type type;
0069             };
0070
0071             // never called, but needed for decltype-based result_of (C++0x)
0072 #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
0073             template<typename Seq>
0074             BOOST_FUSION_GPU_ENABLED
0075             typename result<seq_ref_size(Seq)>::type
0076             operator()(Seq&&) const;
0077 #endif
0078         };
0079
0080         struct poly_min
0081         {
0082             template<typename T>
0083             struct result;
0084
0085             template<typename Lhs, typename Rhs>
0086             struct result<poly_min(Lhs, Rhs)>
0087             {
0088                 typedef typename remove_reference<Lhs>::type lhs;
0089                 typedef typename remove_reference<Rhs>::type rhs;
0090                 typedef typename mpl::min<lhs, rhs>::type type;
0091             };
0092
0093             // never called, but needed for decltype-based result_of (C++0x)
0094 #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
0095             template<typename Lhs, typename Rhs>
0096             BOOST_FUSION_GPU_ENABLED
0097             typename result<poly_min(Lhs, Rhs)>::type
0098             operator()(Lhs&&, Rhs&&) const;
0099 #endif
0100         };
0101
0102         template<typename Sequences>
0103         struct min_size
0104         {
0105             typedef typename result_of::transform<Sequences, detail::seq_ref_size>::type sizes;
0106             typedef typename result_of::fold<sizes, typename result_of::front<sizes>::type, detail::poly_min>::type type;
0107         };
0108     }
0109
0110     struct zip_view_tag;
0111     struct fusion_sequence_tag;
0112
0113     template<typename Sequences>
0114     struct zip_view : sequence_base< zip_view<Sequences> >
0115     {
0116         typedef typename result_of::remove<Sequences, unused_type const&>::type real_sequences;
0117         BOOST_MPL_ASSERT((detail::all_references<Sequences>));
0118         typedef typename detail::strictest_traversal<real_sequences>::type category;
0119         typedef zip_view_tag fusion_tag;
0120         typedef fusion_sequence_tag tag; // this gets picked up by MPL
0121         typedef mpl::true_ is_view;
0122         typedef typename fusion::result_of::as_vector<Sequences>::type sequences;
0123         typedef typename detail::min_size<real_sequences>::type size;
0124
0125         BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
0126         zip_view(
0127             const Sequences& seqs)
0128             : sequences_(seqs)
0129         {}
0130
0131         sequences sequences_;
0132     };
0133 }}
0134
0135 #endif