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
24namespace 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
29template< typename Tag >
30struct 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