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: advance.hpp 49267 2008-10-11 06:19:02Z agurtovoy $
14 // $Date: 2008-10-10 23:19:02 -0700 (Fri, 10 Oct 2008) $
15 // $Revision: 49267 $
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
77