/*=============================================================================
    Copyright (c) 2001-2011 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_IMPL_05042005_0741)
#define FUSION_AT_IMPL_05042005_0741

#include <boost/fusion/support/config.hpp>
#include <boost/fusion/support/detail/access.hpp>
#include <boost/fusion/container/vector/detail/value_at_impl.hpp>
#include <boost/static_assert.hpp>

namespace boost {
namespace fusion {
struct vector_tag;

namespace extension {
template <typename Tag>
struct at_impl;

template <>
struct at_impl<vector_tag>
{
    template <typename Sequence, typename N>
    struct apply
    {
        typedef typename value_at_impl<vector_tag>::template apply<Sequence, N>::type element;
        typedef typename detail::ref_result<element>::type type;

        BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
        static type
        call(Sequence& v)
        {
            BOOST_STATIC_ASSERT((N::value < Sequence::size::value));
            return v.at_impl(N());
        }
    };

    template <typename Sequence, typename N>
    struct apply <Sequence const, N>
    {
        typedef typename value_at_impl<vector_tag>::template apply<Sequence, N>::type element;
        typedef typename detail::cref_result<element>::type type;

        BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
        static type
        call(Sequence const& v)
        {
            BOOST_STATIC_ASSERT((N::value < Sequence::size::value));
            return v.at_impl(N());
        }
    };
};
}
}
}

#endif
