1 | /*============================================================================= |
2 | Copyright (c) 2001-2011 Joel de Guzman |
3 | |
4 | Distributed under the Boost Software License, Version 1.0. (See accompanying |
5 | file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
6 | ==============================================================================*/ |
7 | #if !defined(FUSION_ADVANCE_09172005_1149) |
8 | #define FUSION_ADVANCE_09172005_1149 |
9 | |
10 | #include <boost/fusion/support/config.hpp> |
11 | #include <boost/mpl/int.hpp> |
12 | #include <boost/mpl/if.hpp> |
13 | #include <boost/mpl/eval_if.hpp> |
14 | #include <boost/mpl/identity.hpp> |
15 | #include <boost/fusion/iterator/next.hpp> |
16 | #include <boost/fusion/iterator/prior.hpp> |
17 | |
18 | namespace boost { namespace fusion { namespace advance_detail |
19 | { |
20 | // Default advance implementation, perform next(i) |
21 | // or prior(i) N times. |
22 | |
23 | template <typename Iterator, int N> |
24 | struct forward; |
25 | |
26 | template <typename Iterator, int N> |
27 | struct next_forward |
28 | { |
29 | typedef typename |
30 | forward< |
31 | typename result_of::next<Iterator>::type |
32 | , N-1 |
33 | >::type |
34 | type; |
35 | }; |
36 | |
37 | template <typename Iterator, int N> |
38 | struct forward |
39 | { |
40 | typedef typename |
41 | mpl::eval_if_c< |
42 | (N == 0) |
43 | , mpl::identity<Iterator> |
44 | , next_forward<Iterator, N> |
45 | >::type |
46 | type; |
47 | |
48 | BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED |
49 | static type const& |
50 | call(type const& i) |
51 | { |
52 | return i; |
53 | } |
54 | |
55 | template <typename I> |
56 | BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED |
57 | static type |
58 | call(I const& i) |
59 | { |
60 | return call(fusion::next(i)); |
61 | } |
62 | }; |
63 | |
64 | template <typename Iterator, int N> |
65 | struct backward; |
66 | |
67 | template <typename Iterator, int N> |
68 | struct next_backward |
69 | { |
70 | typedef typename |
71 | backward< |
72 | typename result_of::prior<Iterator>::type |
73 | , N+1 |
74 | >::type |
75 | type; |
76 | }; |
77 | |
78 | template <typename Iterator, int N> |
79 | struct backward |
80 | { |
81 | typedef typename |
82 | mpl::eval_if_c< |
83 | (N == 0) |
84 | , mpl::identity<Iterator> |
85 | , next_backward<Iterator, N> |
86 | >::type |
87 | type; |
88 | |
89 | BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED |
90 | static type const& |
91 | call(type const& i) |
92 | { |
93 | return i; |
94 | } |
95 | |
96 | template <typename I> |
97 | BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED |
98 | static type |
99 | call(I const& i) |
100 | { |
101 | return call(fusion::prior(i)); |
102 | } |
103 | }; |
104 | |
105 | }}} |
106 | |
107 | #endif |
108 | |