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
zip(T0 const & t0,T1 const & t1)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
42             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
49             call(First const& first, mpl::true_)
50             {
51                 return convert_iterator<First>::call(first);
52             }
53 
54             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
zip(T0 const & t0,T1 const & t1,T2 const & t2)55             static type
56             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
zip(T0 const & t0,T1 const & t1,T2 const & t2,T3 const & t3)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     }
zip(T0 const & t0,T1 const & t1,T2 const & t2,T3 const & t3,T4 const & t4)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
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
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