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1 | |
2 | #ifndef BOOST_MPL_ADVANCE_HPP_INCLUDED | |
3 | #define BOOST_MPL_ADVANCE_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/advance_fwd.hpp> | |
18 | #include <boost/mpl/less.hpp> | |
19 | #include <boost/mpl/negate.hpp> | |
20 | #include <boost/mpl/long.hpp> | |
21 | #include <boost/mpl/if.hpp> | |
22 | #include <boost/mpl/tag.hpp> | |
23 | #include <boost/mpl/apply_wrap.hpp> | |
24 | #include <boost/mpl/aux_/advance_forward.hpp> | |
25 | #include <boost/mpl/aux_/advance_backward.hpp> | |
26 | #include <boost/mpl/aux_/value_wknd.hpp> | |
27 | #include <boost/mpl/aux_/na_spec.hpp> | |
28 | #include <boost/mpl/aux_/nttp_decl.hpp> | |
29 | ||
30 | namespace boost { namespace mpl { | |
31 | ||
32 | // default implementation for forward/bidirectional iterators | |
33 | template< typename Tag > | |
34 | struct advance_impl | |
35 | { | |
36 | template< typename Iterator, typename N > struct apply | |
37 | { | |
38 | typedef typename less< N,long_<0> >::type backward_; | |
39 | typedef typename if_< backward_, negate<N>, N >::type offset_; | |
40 | ||
41 | typedef typename if_< | |
42 | backward_ | |
43 | , aux::advance_backward< BOOST_MPL_AUX_VALUE_WKND(offset_)::value > | |
44 | , aux::advance_forward< BOOST_MPL_AUX_VALUE_WKND(offset_)::value > | |
45 | >::type f_; | |
46 | ||
47 | typedef typename apply_wrap1<f_,Iterator>::type type; | |
48 | }; | |
49 | }; | |
50 | ||
51 | ||
52 | template< | |
53 | typename BOOST_MPL_AUX_NA_PARAM(Iterator) | |
54 | , typename BOOST_MPL_AUX_NA_PARAM(N) | |
55 | > | |
56 | struct advance | |
57 | : advance_impl< typename tag<Iterator>::type > | |
58 | ::template apply<Iterator,N> | |
59 | { | |
60 | }; | |
61 | ||
62 | template< | |
63 | typename Iterator | |
64 | , BOOST_MPL_AUX_NTTP_DECL(long, N) | |
65 | > | |
66 | struct advance_c | |
67 | : advance_impl< typename tag<Iterator>::type > | |
68 | ::template apply<Iterator,long_<N> > | |
69 | { | |
70 | }; | |
71 | ||
72 | BOOST_MPL_AUX_NA_SPEC(2, advance) | |
73 | ||
74 | }} | |
75 | ||
76 | #endif // BOOST_MPL_ADVANCE_HPP_INCLUDED |