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1 | /*============================================================================= |
2 | Copyright (c) 2011 Eric Niebler | |
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 | ||
8 | #if !defined(BOOST_FUSION_SINGLE_VIEW_VALUE_AT_IMPL_JUL_07_2011_1348PM) | |
9 | #define BOOST_FUSION_SINGLE_VIEW_VALUE_AT_IMPL_JUL_07_2011_1348PM | |
10 | ||
11 | #include <boost/fusion/support/config.hpp> | |
12 | #include <boost/mpl/int.hpp> | |
13 | #include <boost/mpl/assert.hpp> | |
14 | #include <boost/mpl/equal_to.hpp> | |
15 | #include <boost/fusion/sequence/intrinsic/value_at.hpp> | |
16 | ||
17 | namespace boost { namespace fusion | |
18 | { | |
19 | struct single_view_tag; | |
20 | ||
21 | namespace extension | |
22 | { | |
23 | template<typename Tag> | |
24 | struct value_at_impl; | |
25 | ||
26 | template<> | |
27 | struct value_at_impl<single_view_tag> | |
28 | { | |
29 | template<typename Sequence, typename N> | |
30 | struct apply | |
31 | { | |
32 | BOOST_MPL_ASSERT((mpl::equal_to<N, mpl::int_<0> >)); | |
33 | typedef typename Sequence::value_type type; | |
34 | }; | |
35 | }; | |
36 | } | |
37 | ||
38 | }} | |
39 | ||
40 | #endif |