| /*============================================================================= |
| 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_VALUE_AT_IMPL_07172005_0952) |
| #define FUSION_VALUE_AT_IMPL_07172005_0952 |
| |
| #include <boost/fusion/support/detail/access.hpp> |
| #include <boost/type_traits/is_const.hpp> |
| #include <boost/mpl/eval_if.hpp> |
| #include <boost/mpl/bool.hpp> |
| |
| namespace boost { namespace fusion |
| { |
| struct cons_tag; |
| |
| namespace extension |
| { |
| template <typename Tag> |
| struct value_at_impl; |
| |
| template <> |
| struct value_at_impl<cons_tag> |
| { |
| template <typename Sequence, typename N> |
| struct apply |
| { |
| typedef typename |
| mpl::eval_if< |
| mpl::bool_<N::value == 0> |
| , mpl::identity<typename Sequence::car_type> |
| , apply<typename Sequence::cdr_type, mpl::int_<N::value-1> > |
| >::type |
| type; |
| }; |
| }; |
| } |
| }} |
| |
| #endif |