1 /*=============================================================================
2 Copyright (c) 2001-2011 Joel de Guzman
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_VALUE_AT_05052005_0229)
8 #define FUSION_VALUE_AT_05052005_0229
10 #include <boost/fusion/support/config.hpp>
11 #include <boost/mpl/int.hpp>
12 #include <boost/mpl/if.hpp>
13 #include <boost/mpl/or.hpp>
14 #include <boost/mpl/less.hpp>
15 #include <boost/mpl/empty_base.hpp>
16 #include <boost/fusion/sequence/intrinsic_fwd.hpp>
17 #include <boost/fusion/support/tag_of.hpp>
18 #include <boost/fusion/support/category_of.hpp>
20 namespace boost { namespace fusion
23 struct sequence_facade_tag;
24 struct boost_tuple_tag; // boost::tuples::tuple tag
25 struct boost_array_tag; // boost::array tag
26 struct mpl_sequence_tag; // mpl sequence tag
27 struct std_pair_tag; // std::pair tag
31 template <typename Tag>
34 template <typename Sequence, typename N>
39 struct value_at_impl<sequence_facade_tag>
41 template <typename Sequence, typename N>
42 struct apply : Sequence::template value_at<Sequence, N> {};
46 struct value_at_impl<boost_tuple_tag>;
49 struct value_at_impl<boost_array_tag>;
52 struct value_at_impl<mpl_sequence_tag>;
55 struct value_at_impl<std_pair_tag>;
60 template <typename Sequence, typename N, typename Tag>
64 mpl::less<N, typename extension::size_impl<Tag>::template apply<Sequence>::type>
65 , traits::is_unbounded<Sequence>
67 , typename extension::value_at_impl<Tag>::template apply<Sequence, N>
75 template <typename Sequence, typename N>
77 : detail::value_at_impl<Sequence, N, typename detail::tag_of<Sequence>::type>
80 template <typename Sequence, int N>
82 : fusion::result_of::value_at<Sequence, mpl::int_<N> >