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1 | /*============================================================================= |
2 | Copyright (c) 2005-2012 Joel de Guzman | |
3 | Copyright (c) 2005-2006 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(BOOST_FUSION_DEQUE_VALUE_AT_IMPL_08122006_0756) | |
9 | #define BOOST_FUSION_DEQUE_VALUE_AT_IMPL_08122006_0756 | |
10 | ||
11 | #include <boost/fusion/support/config.hpp> | |
12 | #include <boost/fusion/container/deque/detail/keyed_element.hpp> | |
13 | ||
14 | #include <boost/mpl/equal_to.hpp> | |
15 | #include <boost/mpl/assert.hpp> | |
16 | ||
17 | namespace boost { namespace fusion | |
18 | { | |
19 | struct deque_tag; | |
20 | ||
21 | namespace extension | |
22 | { | |
23 | template<typename T> | |
24 | struct value_at_impl; | |
25 | ||
26 | template<> | |
27 | struct value_at_impl<deque_tag> | |
28 | { | |
29 | template<typename Sequence, typename N> | |
30 | struct apply | |
31 | { | |
32 | typedef typename Sequence::next_up next_up; | |
33 | typedef typename Sequence::next_down next_down; | |
34 | BOOST_MPL_ASSERT_RELATION(next_down::value, !=, next_up::value); | |
35 | ||
36 | static int const offset = next_down::value + 1; | |
37 | typedef mpl::int_<(N::value + offset)> adjusted_index; | |
38 | typedef typename | |
39 | detail::keyed_element_value_at<Sequence, adjusted_index>::type | |
40 | type; | |
41 | }; | |
42 | }; | |
43 | } | |
44 | }} | |
45 | ||
46 | #endif |