1 /*============================================================================= 2 Copyright (c) 2001-2011 Joel de Guzman 3 4 Distributed under the Boost Software License, Version 1.0. (See accompanying 5 file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 6 ==============================================================================*/ 7 #if !defined(FUSION_ERASE_07232005_0534) 8 #define FUSION_ERASE_07232005_0534 9 10 #include <boost/fusion/support/config.hpp> 11 #include <boost/fusion/iterator/equal_to.hpp> 12 #include <boost/fusion/iterator/mpl/convert_iterator.hpp> 13 #include <boost/fusion/view/joint_view/joint_view.hpp> 14 #include <boost/fusion/view/iterator_range/iterator_range.hpp> 15 #include <boost/fusion/support/detail/as_fusion_element.hpp> 16 #include <boost/fusion/sequence/intrinsic/begin.hpp> 17 #include <boost/fusion/sequence/intrinsic/end.hpp> 18 #include <boost/fusion/adapted/mpl/mpl_iterator.hpp> 19 #include <boost/fusion/support/is_sequence.hpp> 20 #include <boost/utility/enable_if.hpp> 21 #include <boost/mpl/if.hpp> 22 23 namespace boost { namespace fusion 24 { 25 namespace result_of 26 { 27 template <typename Sequence, typename First> 28 struct compute_erase_last // put this in detail!!! 29 { 30 typedef typename result_of::end<Sequence>::type seq_last_type; 31 typedef typename convert_iterator<First>::type first_type; 32 typedef typename 33 mpl::if_< 34 result_of::equal_to<first_type, seq_last_type> 35 , first_type 36 , typename result_of::next<first_type>::type 37 >::type 38 type; 39 40 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED 41 static type callboost::fusion::result_of::compute_erase_last42 call(First const& first, mpl::false_) 43 { 44 return fusion::next(convert_iterator<First>::call(first)); 45 } 46 47 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED 48 static type callboost::fusion::result_of::compute_erase_last49 call(First const& first, mpl::true_) 50 { 51 return convert_iterator<First>::call(first); 52 } 53 54 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED 55 static type callboost::fusion::result_of::compute_erase_last56 call(First const& first) 57 { 58 return call(first, result_of::equal_to<first_type, seq_last_type>()); 59 } 60 }; 61 62 struct use_default; 63 64 template <class T, class Default> 65 struct fusion_default_help 66 : mpl::if_< 67 is_same<T, use_default> 68 , Default 69 , T 70 > 71 { 72 }; 73 74 template < 75 typename Sequence 76 , typename First 77 , typename Last = use_default> 78 struct erase 79 { 80 typedef typename result_of::begin<Sequence>::type seq_first_type; 81 typedef typename result_of::end<Sequence>::type seq_last_type; 82 BOOST_STATIC_ASSERT((!result_of::equal_to<seq_first_type, seq_last_type>::value)); 83 84 typedef First FirstType; 85 typedef typename 86 fusion_default_help< 87 Last 88 , typename compute_erase_last<Sequence, First>::type 89 >::type 90 LastType; 91 92 typedef typename convert_iterator<FirstType>::type first_type; 93 typedef typename convert_iterator<LastType>::type last_type; 94 typedef iterator_range<seq_first_type, first_type> left_type; 95 typedef iterator_range<last_type, seq_last_type> right_type; 96 typedef joint_view<left_type, right_type> type; 97 }; 98 } 99 100 template <typename Sequence, typename First> 101 BOOST_CXX14_CONSTEXPR BOOST_FUSION_GPU_ENABLED 102 inline typename 103 lazy_enable_if< 104 traits::is_sequence<Sequence> 105 , typename result_of::erase<Sequence const, First> 106 >::type erase(Sequence const & seq,First const & first)107 erase(Sequence const& seq, First const& first) 108 { 109 typedef result_of::erase<Sequence const, First> result_of; 110 typedef typename result_of::left_type left_type; 111 typedef typename result_of::right_type right_type; 112 typedef typename result_of::type result_type; 113 114 left_type left( 115 fusion::begin(seq) 116 , convert_iterator<First>::call(first)); 117 right_type right( 118 fusion::result_of::compute_erase_last<Sequence const, First>::call(first) 119 , fusion::end(seq)); 120 return result_type(left, right); 121 } 122 123 template <typename Sequence, typename First, typename Last> 124 BOOST_CXX14_CONSTEXPR BOOST_FUSION_GPU_ENABLED 125 inline typename result_of::erase<Sequence const, First, Last>::type erase(Sequence const & seq,First const & first,Last const & last)126 erase(Sequence const& seq, First const& first, Last const& last) 127 { 128 typedef result_of::erase<Sequence const, First, Last> result_of; 129 typedef typename result_of::left_type left_type; 130 typedef typename result_of::right_type right_type; 131 typedef typename result_of::type result_type; 132 133 left_type left(fusion::begin(seq), first); 134 right_type right(last, fusion::end(seq)); 135 return result_type(left, right); 136 } 137 }} 138 139 #endif 140 141