algorithm/transformation/erase.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_ERASE_07232005_0534)
0008 #define FUSION_ERASE_07232005_0534
0009
0010 #include <boost/fusion/support/config.hpp>
0011 #include <boost/fusion/iterator/equal_to.hpp>
0012 #include <boost/fusion/iterator/mpl/convert_iterator.hpp>
0013 #include <boost/fusion/view/joint_view/joint_view.hpp>
0014 #include <boost/fusion/view/iterator_range/iterator_range.hpp>
0015 #include <boost/fusion/support/detail/as_fusion_element.hpp>
0016 #include <boost/fusion/sequence/intrinsic/begin.hpp>
0017 #include <boost/fusion/sequence/intrinsic/end.hpp>
0018 #include <boost/fusion/adapted/mpl/mpl_iterator.hpp>
0019 #include <boost/fusion/support/is_sequence.hpp>
0020 #include <boost/utility/enable_if.hpp>
0021 #include <boost/mpl/if.hpp>
0022
0023 namespace boost { namespace fusion
0024 {
0025     namespace result_of
0026     {
0027         template <typename Sequence, typename First>
0028         struct compute_erase_last // put this in detail!!!
0029         {
0030             typedef typename result_of::end<Sequence>::type seq_last_type;
0031             typedef typename convert_iterator<First>::type first_type;
0032             typedef typename
0033                 mpl::if_<
0034                     result_of::equal_to<first_type, seq_last_type>
0035                   , first_type
0036                   , typename result_of::next<first_type>::type
0037                 >::type
0038             type;
0039
0040             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
0041             static type
0042             call(First const& first, mpl::false_)
0043             {
0044                 return fusion::next(convert_iterator<First>::call(first));
0045             }
0046
0047             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
0048             static type
0049             call(First const& first, mpl::true_)
0050             {
0051                 return convert_iterator<First>::call(first);
0052             }
0053
0054             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
0055             static type
0056             call(First const& first)
0057             {
0058                 return call(first, result_of::equal_to<first_type, seq_last_type>());
0059             }
0060         };
0061
0062         struct use_default;
0063
0064         template <class T, class Default>
0065         struct fusion_default_help
0066           : mpl::if_<
0067                 is_same<T, use_default>
0068               , Default
0069               , T
0070             >
0071         {
0072         };
0073
0074         template <
0075             typename Sequence
0076           , typename First
0077           , typename Last = use_default>
0078         struct erase
0079         {
0080             typedef typename result_of::begin<Sequence>::type seq_first_type;
0081             typedef typename result_of::end<Sequence>::type seq_last_type;
0082             BOOST_STATIC_ASSERT((!result_of::equal_to<seq_first_type, seq_last_type>::value));
0083
0084             typedef First FirstType;
0085             typedef typename
0086                 fusion_default_help<
0087                     Last
0088                   , typename compute_erase_last<Sequence, First>::type
0089                 >::type
0090             LastType;
0091
0092             typedef typename convert_iterator<FirstType>::type first_type;
0093             typedef typename convert_iterator<LastType>::type last_type;
0094             typedef iterator_range<seq_first_type, first_type> left_type;
0095             typedef iterator_range<last_type, seq_last_type> right_type;
0096             typedef joint_view<left_type, right_type> type;
0097         };
0098     }
0099
0100     template <typename Sequence, typename First>
0101     BOOST_CXX14_CONSTEXPR BOOST_FUSION_GPU_ENABLED
0102     inline typename
0103         lazy_enable_if<
0104             traits::is_sequence<Sequence>
0105           , typename result_of::erase<Sequence const, First>
0106         >::type
0107     erase(Sequence const& seq, First const& first)
0108     {
0109         typedef result_of::erase<Sequence const, First> result_of;
0110         typedef typename result_of::left_type left_type;
0111         typedef typename result_of::right_type right_type;
0112         typedef typename result_of::type result_type;
0113
0114         left_type left(
0115             fusion::begin(seq)
0116           , convert_iterator<First>::call(first));
0117         right_type right(
0118             fusion::result_of::compute_erase_last<Sequence const, First>::call(first)
0119           , fusion::end(seq));
0120         return result_type(left, right);
0121     }
0122
0123     template <typename Sequence, typename First, typename Last>
0124     BOOST_CXX14_CONSTEXPR BOOST_FUSION_GPU_ENABLED
0125     inline typename result_of::erase<Sequence const, First, Last>::type
0126     erase(Sequence const& seq, First const& first, Last const& last)
0127     {
0128         typedef result_of::erase<Sequence const, First, Last> result_of;
0129         typedef typename result_of::left_type left_type;
0130         typedef typename result_of::right_type right_type;
0131         typedef typename result_of::type result_type;
0132
0133         left_type left(fusion::begin(seq), first);
0134         right_type right(last, fusion::end(seq));
0135         return result_type(left, right);
0136     }
0137 }}
0138
0139 #endif
0140