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 |
70 | |