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1 | ||
2 | #ifndef BOOST_MPL_AUX_ERASE_IMPL_HPP_INCLUDED | |
3 | #define BOOST_MPL_AUX_ERASE_IMPL_HPP_INCLUDED | |
4 | ||
5 | // Copyright Aleksey Gurtovoy 2000-2004 | |
6 | // | |
7 | // Distributed under the Boost Software License, Version 1.0. | |
8 | // (See accompanying file LICENSE_1_0.txt or copy at | |
9 | // http://www.boost.org/LICENSE_1_0.txt) | |
10 | // | |
11 | // See http://www.boost.org/libs/mpl for documentation. | |
12 | ||
13 | // $Id$ | |
14 | // $Date$ | |
15 | // $Revision$ | |
16 | ||
17 | #include <boost/mpl/clear.hpp> | |
18 | #include <boost/mpl/push_front.hpp> | |
19 | #include <boost/mpl/reverse_fold.hpp> | |
20 | #include <boost/mpl/iterator_range.hpp> | |
21 | #include <boost/mpl/next.hpp> | |
22 | #include <boost/mpl/aux_/na.hpp> | |
23 | ||
24 | namespace boost { namespace mpl { | |
25 | ||
26 | // default implementation; conrete sequences might override it by | |
27 | // specializing either the 'erase_impl' or the primary 'erase' template | |
28 | ||
29 | template< typename Tag > | |
30 | struct erase_impl | |
31 | { | |
32 | template< | |
33 | typename Sequence | |
34 | , typename First | |
35 | , typename Last | |
36 | > | |
37 | struct apply | |
38 | { | |
39 | typedef typename if_na< Last,typename next<First>::type >::type last_; | |
40 | ||
41 | // 1st half: [begin, first) | |
42 | typedef iterator_range< | |
43 | typename begin<Sequence>::type | |
44 | , First | |
45 | > first_half_; | |
46 | ||
47 | // 2nd half: [last, end) ... that is, [last + 1, end) | |
48 | typedef iterator_range< | |
49 | last_ | |
50 | , typename end<Sequence>::type | |
51 | > second_half_; | |
52 | ||
53 | typedef typename reverse_fold< | |
54 | second_half_ | |
55 | , typename clear<Sequence>::type | |
56 | , push_front<_,_> | |
57 | >::type half_sequence_; | |
58 | ||
59 | typedef typename reverse_fold< | |
60 | first_half_ | |
61 | , half_sequence_ | |
62 | , push_front<_,_> | |
63 | >::type type; | |
64 | }; | |
65 | }; | |
66 | ||
67 | }} | |
68 | ||
69 | #endif // BOOST_MPL_AUX_ERASE_IMPL_HPP_INCLUDED |