| /*============================================================================= |
| Copyright (c) 2001-2006 Joel de Guzman |
| |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
| ==============================================================================*/ |
| #if !defined(FUSION_AT_05042005_0722) |
| #define FUSION_AT_05042005_0722 |
| |
| #include <boost/mpl/int.hpp> |
| #include <boost/type_traits/is_const.hpp> |
| #include <boost/fusion/support/tag_of.hpp> |
| #include <boost/fusion/support/detail/access.hpp> |
| |
| namespace boost { namespace fusion |
| { |
| // Special tags: |
| struct sequence_facade_tag; |
| struct boost_tuple_tag; // boost::tuples::tuple tag |
| struct array_tag; // boost::array tag |
| struct mpl_sequence_tag; // mpl sequence tag |
| struct std_pair_tag; // std::pair tag |
| |
| namespace extension |
| { |
| template <typename Tag> |
| struct at_impl |
| { |
| template <typename Sequence, typename N> |
| struct apply; |
| }; |
| |
| template <> |
| struct at_impl<sequence_facade_tag> |
| { |
| template <typename Sequence, typename N> |
| struct apply : Sequence::template at<Sequence, N> {}; |
| }; |
| |
| template <> |
| struct at_impl<boost_tuple_tag>; |
| |
| template <> |
| struct at_impl<array_tag>; |
| |
| template <> |
| struct at_impl<mpl_sequence_tag>; |
| |
| template <> |
| struct at_impl<std_pair_tag>; |
| } |
| |
| namespace result_of |
| { |
| template <typename Sequence, typename N> |
| struct at |
| : extension::at_impl<typename detail::tag_of<Sequence>::type>:: |
| template apply<Sequence, N> |
| {}; |
| |
| template <typename Sequence, int N> |
| struct at_c |
| : at<Sequence, mpl::int_<N> > |
| {}; |
| } |
| |
| |
| template <typename N, typename Sequence> |
| inline typename |
| lazy_disable_if< |
| is_const<Sequence> |
| , result_of::at<Sequence, N> |
| >::type |
| at(Sequence& seq) |
| { |
| return result_of::at<Sequence, N>::call(seq); |
| } |
| |
| template <typename N, typename Sequence> |
| inline typename result_of::at<Sequence const, N>::type |
| at(Sequence const& seq) |
| { |
| return result_of::at<Sequence const, N>::call(seq); |
| } |
| |
| template <int N, typename Sequence> |
| inline typename |
| lazy_disable_if< |
| is_const<Sequence> |
| , result_of::at_c<Sequence, N> |
| >::type |
| at_c(Sequence& seq) |
| { |
| return fusion::at<mpl::int_<N> >(seq); |
| } |
| |
| template <int N, typename Sequence> |
| inline typename result_of::at_c<Sequence const, N>::type |
| at_c(Sequence const& seq) |
| { |
| return fusion::at<mpl::int_<N> >(seq); |
| } |
| }} |
| |
| #endif |
| |