/*============================================================================= | |
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 boost_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<boost_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 | |