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1 | /*============================================================================= |
2 | Copyright (c) 2001-2011 Joel de Guzman | |
3 | Copyright (c) 2006 Dan Marsden | |
4 | ||
5 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
6 | file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
7 | ==============================================================================*/ | |
8 | #if !defined(FUSION_PRIOR_IMPL_20060124_2006) | |
9 | #define FUSION_PRIOR_IMPL_20060124_2006 | |
10 | ||
11 | #include <boost/fusion/support/config.hpp> | |
12 | #include <boost/fusion/view/zip_view/zip_view_iterator_fwd.hpp> | |
13 | #include <boost/fusion/iterator/prior.hpp> | |
14 | #include <boost/fusion/algorithm/transformation/transform.hpp> | |
15 | #include <boost/fusion/support/unused.hpp> | |
16 | #include <boost/mpl/eval_if.hpp> | |
17 | #include <boost/mpl/identity.hpp> | |
18 | #include <boost/type_traits/is_same.hpp> | |
19 | #include <boost/type_traits/remove_reference.hpp> | |
20 | #include <boost/type_traits/remove_const.hpp> | |
21 | ||
22 | namespace boost { namespace fusion { | |
23 | ||
24 | struct zip_view_iterator_tag; | |
25 | ||
26 | namespace detail | |
27 | { | |
28 | struct poly_prior | |
29 | { | |
30 | template<typename Sig> | |
31 | struct result; | |
32 | ||
33 | template<typename It> | |
34 | struct result<poly_prior(It)> | |
35 | { | |
36 | typedef typename remove_const< | |
37 | typename remove_reference<It>::type>::type it; | |
38 | typedef typename mpl::eval_if<is_same<it, unused_type>, | |
39 | mpl::identity<unused_type>, | |
40 | result_of::prior<it> >::type type; | |
41 | }; | |
42 | ||
43 | template<typename It> | |
44 | BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED | |
45 | typename result<poly_prior(It)>::type | |
46 | operator()(const It& it) const | |
47 | { | |
48 | return fusion::prior(it); | |
49 | } | |
50 | ||
51 | BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED | |
52 | unused_type operator()(unused_type const&) const | |
53 | { | |
54 | return unused_type(); | |
55 | } | |
56 | }; | |
57 | } | |
58 | ||
59 | namespace extension | |
60 | { | |
61 | template<typename Tag> | |
62 | struct prior_impl; | |
63 | ||
64 | template<> | |
65 | struct prior_impl<zip_view_iterator_tag> | |
66 | { | |
67 | template<typename Iterator> | |
68 | struct apply | |
69 | { | |
70 | typedef zip_view_iterator< | |
71 | typename result_of::transform<typename Iterator::iterators, detail::poly_prior>::type, | |
72 | typename Iterator::category> type; | |
73 | ||
74 | BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED | |
75 | static type | |
76 | call(Iterator const& it) | |
77 | ||
78 | { | |
79 | return type( | |
80 | fusion::transform(it.iterators_, detail::poly_prior())); | |
81 | } | |
82 | }; | |
83 | }; | |
84 | } | |
85 | }} | |
86 | ||
87 | #endif |