#ifndef BOOST_MPL_ITER_FOLD_IF_HPP_INCLUDED

#define BOOST_MPL_ITER_FOLD_IF_HPP_INCLUDED

// Copyright Aleksey Gurtovoy 2003-2004

// Copyright Eric Friedman 2003

//

// 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.

// $Id$

// $Date$

// $Revision$

#include <boost/mpl/begin_end.hpp>

#include <boost/mpl/logical.hpp>

#include <boost/mpl/always.hpp>

#include <boost/mpl/eval_if.hpp>

#include <boost/mpl/if.hpp>

#include <boost/mpl/pair.hpp>

#include <boost/mpl/apply.hpp>

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

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

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

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

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

#include <boost/type_traits/is_same.hpp>

namespace boost { namespace mpl {

namespace aux {

template< typename Predicate, typename LastIterator >

struct iter_fold_if_pred

{

    template< typename State, typename Iterator > struct apply

#if !defined(BOOST_MPL_CFG_NO_NESTED_FORWARDING)

        : and_<

              not_< is_same<Iterator,LastIterator> >

            , apply1<Predicate,Iterator>

            >

    {

#else

    {

        typedef and_<

              not_< is_same<Iterator,LastIterator> >

            , apply1<Predicate,Iterator>

            > type;

#endif

    };

};

} // namespace aux

template<

      typename BOOST_MPL_AUX_NA_PARAM(Sequence)

    , typename BOOST_MPL_AUX_NA_PARAM(State)

    , typename BOOST_MPL_AUX_NA_PARAM(ForwardOp)

    , typename BOOST_MPL_AUX_NA_PARAM(ForwardPredicate)

    , typename BOOST_MPL_AUX_NA_PARAM(BackwardOp)

    , typename BOOST_MPL_AUX_NA_PARAM(BackwardPredicate)

    >

struct iter_fold_if

{

    typedef typename begin<Sequence>::type first_;

    typedef typename end<Sequence>::type last_;

    typedef typename eval_if<

          is_na<BackwardPredicate>

        , if_< is_na<BackwardOp>, always<false_>, always<true_> >

        , identity<BackwardPredicate>

        >::type backward_pred_;

// cwpro8 doesn't like 'cut-off' type here (use typedef instead)

#if !BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3003)) && !BOOST_WORKAROUND(__IBMCPP__, BOOST_TESTED_AT(600))

    struct result_ :

#else

    typedef

#endif

        aux::iter_fold_if_impl<

          first_

        , State

        , ForwardOp

        , protect< aux::iter_fold_if_pred< ForwardPredicate,last_ > >

        , BackwardOp

        , backward_pred_

        >

#if !BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3003)) && !BOOST_WORKAROUND(__IBMCPP__, BOOST_TESTED_AT(600))

    { };

#else

    result_;

#endif

public:

    typedef pair<

          typename result_::state

        , typename result_::iterator

        > type;

    BOOST_MPL_AUX_LAMBDA_SUPPORT(

          6

        , iter_fold_if

        , (Sequence,State,ForwardOp,ForwardPredicate,BackwardOp,BackwardPredicate)

        )

};

BOOST_MPL_AUX_NA_SPEC(6, iter_fold_if)

}}

#endif // BOOST_MPL_ITER_FOLD_IF_HPP_INCLUDED