#ifndef BOOST_MPL_VECTOR_AUX_AT_HPP_INCLUDED

#define BOOST_MPL_VECTOR_AUX_AT_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: /cvsroot/boost/boost/boost/mpl/vector/aux_/at.hpp,v $

// $Date: 2004/12/20 19:35:33 $

// $Revision: 1.6 $

#include <boost/mpl/at_fwd.hpp>

#include <boost/mpl/vector/aux_/tag.hpp>

#include <boost/mpl/long.hpp>

#include <boost/mpl/void.hpp>

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

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

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

#include <boost/mpl/aux_/config/typeof.hpp>

#include <boost/mpl/aux_/config/ctps.hpp>

namespace boost { namespace mpl {

#if defined(BOOST_MPL_CFG_TYPEOF_BASED_SEQUENCES)

template< typename Vector, long n_ >

struct v_at_impl

{

    typedef long_< (Vector::lower_bound_::value + n_) > index_;

    typedef __typeof__( Vector::item_(index_()) ) type;

};

template< typename Vector, long n_ >

struct v_at

    : aux::wrapped_type< typename v_at_impl<Vector,n_>::type >

{

};

template<>

struct at_impl< aux::vector_tag >

{

    template< typename Vector, typename N > struct apply

        : v_at<

              Vector

            , BOOST_MPL_AUX_VALUE_WKND(N)::value

            >

    {

    };

};

#else

#   if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) \

    && !defined(BOOST_MPL_CFG_NO_NONTYPE_TEMPLATE_PARTIAL_SPEC)

template< typename Vector, BOOST_MPL_AUX_NTTP_DECL(long, n_) > struct v_at;

template< BOOST_MPL_AUX_NTTP_DECL(long, n_) >

struct at_impl< aux::vector_tag<n_> >

{

    template< typename Vector, typename N > struct apply

#if !defined(__BORLANDC__)

        : v_at<

              Vector

            , BOOST_MPL_AUX_VALUE_WKND(N)::value

            >

    {

#else

    {

        typedef typename v_at<

              Vector

            , BOOST_MPL_AUX_VALUE_WKND(N)::value

            >::type type;

#endif

    };

};

#   else

namespace aux {

template< BOOST_MPL_AUX_NTTP_DECL(long, n_) > struct v_at_impl

{

    template< typename V > struct result_;

};

// to work around ETI, etc.

template<> struct v_at_impl<-1>

{

    template< typename V > struct result_

    {

        typedef void_ type;

    };

};

} // namespace aux

template< typename T, BOOST_MPL_AUX_NTTP_DECL(long, n_) >

struct v_at

    : aux::v_at_impl<n_>::template result_<T>

{

};

#   endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION

#endif // BOOST_MPL_CFG_TYPEOF_BASED_SEQUENCES

}}

#endif // BOOST_MPL_VECTOR_AUX_AT_HPP_INCLUDED