

#ifndef BOOST_MPL_AUX_AT_IMPL_HPP_INCLUDED

#define BOOST_MPL_AUX_AT_IMPL_HPP_INCLUDED



// Copyright Aleksey Gurtovoy 2000-2004

//

// 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)

//

// See http://www.boost.org/libs/mpl for documentation.



// $Source$

// $Date: 2004-09-02 11:41:37 -0400 (Thu, 02 Sep 2004) $

// $Revision: 24874 $



#include <boost/mpl/begin_end.hpp>

#include <boost/mpl/advance.hpp>

#include <boost/mpl/deref.hpp>

#include <boost/mpl/aux_/traits_lambda_spec.hpp>



namespace boost { namespace mpl {



// default implementation; conrete sequences might override it by 

// specializing either the 'at_impl' or the primary 'at' template



template< typename Tag >

struct at_impl

{

    template< typename Sequence, typename N > struct apply

    {

        typedef typename advance<

              typename begin<Sequence>::type

            , N

            >::type iter_;



        typedef typename deref<iter_>::type type;

    };

};



BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC(2, at_impl)



}}



#endif // BOOST_MPL_AUX_AT_IMPL_HPP_INCLUDED

