| /*============================================================================= |
| Copyright (c) 2001-2006 Joel de Guzman |
| Copyright (c) 2005-2006 Dan Marsden |
| |
| 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(BOOST_FUSION_AT_IMPL_24122005_1807) |
| #define BOOST_FUSION_AT_IMPL_24122005_1807 |
| |
| #include <boost/fusion/support/detail/access.hpp> |
| #include <boost/mpl/assert.hpp> |
| #include <boost/mpl/int.hpp> |
| |
| namespace boost { namespace fusion |
| { |
| struct struct_tag; |
| |
| namespace extension |
| { |
| template<typename T> |
| struct at_impl; |
| |
| template <typename Struct, int N> |
| struct struct_member; |
| |
| template <typename Struct> |
| struct struct_size; |
| |
| template <> |
| struct at_impl<struct_tag> |
| { |
| template <typename Sequence, typename N> |
| struct apply |
| { |
| static int const n_value = N::value; |
| BOOST_MPL_ASSERT_RELATION( |
| n_value, <=, extension::struct_size<Sequence>::value); |
| |
| typedef typename |
| extension::struct_member<Sequence, N::value> |
| element; |
| |
| typedef typename |
| mpl::eval_if< |
| is_const<Sequence> |
| , detail::cref_result<element> |
| , detail::ref_result<element> |
| >::type |
| type; |
| |
| static type |
| call(Sequence& seq) |
| { |
| return extension:: |
| struct_member<Sequence, N::value>::call(seq); |
| } |
| }; |
| }; |
| } |
| }} |
| |
| #endif |