

#ifndef BOOST_MPL_PAIR_VIEW_HPP_INCLUDED

#define BOOST_MPL_PAIR_VIEW_HPP_INCLUDED



// Copyright David Abrahams 2003-2004

// Copyright Aleksey Gurtovoy 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: 2004-11-27 20:58:27 -0500 (Sat, 27 Nov 2004) $

// $Revision: 26325 $



#include <boost/mpl/begin_end.hpp>

#include <boost/mpl/iterator_category.hpp>

#include <boost/mpl/advance.hpp>

#include <boost/mpl/distance.hpp>

#include <boost/mpl/next_prior.hpp>

#include <boost/mpl/deref.hpp>

#include <boost/mpl/min_max.hpp>

#include <boost/mpl/pair.hpp>

#include <boost/mpl/iterator_tags.hpp>

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

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



namespace boost { namespace mpl {



namespace aux {

struct pair_iter_tag;



#if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)



template< typename Iter1, typename Iter2, typename Category >

struct pair_iter;



template< typename Category > struct prior_pair_iter

{

    template< typename Iter1, typename Iter2 > struct apply

    {

        typedef typename mpl::prior<Iter1>::type i1_;

        typedef typename mpl::prior<Iter2>::type i2_;

        typedef pair_iter<i1_,i2_,Category> type;

    };

};



template<> struct prior_pair_iter<forward_iterator_tag>

{

    template< typename Iter1, typename Iter2 > struct apply

    {

        typedef pair_iter<Iter1,Iter2,forward_iterator_tag> type;

    };

};



#endif

}



template< 

      typename Iter1

    , typename Iter2

    , typename Category

    >

struct pair_iter

{

    typedef aux::pair_iter_tag tag;

    typedef Category category;

    typedef Iter1 first;

    typedef Iter2 second;

    

#if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)

    typedef pair< 

          typename deref<Iter1>::type

        , typename deref<Iter2>::type

        > type;



    typedef typename mpl::next<Iter1>::type i1_;

    typedef typename mpl::next<Iter2>::type i2_;

    typedef pair_iter<i1_,i2_,Category> next;

    

    typedef apply_wrap2< aux::prior_pair_iter<Category>,Iter1,Iter2 >::type prior;

#endif

};





#if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)



template< typename Iter1, typename Iter2, typename C >

struct deref< pair_iter<Iter1,Iter2,C> >

{

    typedef pair< 

          typename deref<Iter1>::type

        , typename deref<Iter2>::type

        > type;

};



template< typename Iter1, typename Iter2, typename C >

struct next< pair_iter<Iter1,Iter2,C> >

{

    typedef typename mpl::next<Iter1>::type i1_;

    typedef typename mpl::next<Iter2>::type i2_;

    typedef pair_iter<i1_,i2_,C> type;

};



template< typename Iter1, typename Iter2, typename C >

struct prior< pair_iter<Iter1,Iter2,C> >

{

    typedef typename mpl::prior<Iter1>::type i1_;

    typedef typename mpl::prior<Iter2>::type i2_;

    typedef pair_iter<i1_,i2_,C> type;

};



#endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION





template<> struct advance_impl<aux::pair_iter_tag>

{

    template< typename Iter, typename D > struct apply

    {

        typedef typename mpl::advance< typename Iter::first,D >::type i1_;

        typedef typename mpl::advance< typename Iter::second,D >::type i2_;

        typedef pair_iter<i1_,i2_,typename Iter::category> type;

    };

};



template<> struct distance_impl<aux::pair_iter_tag>

{

    template< typename Iter1, typename Iter2 > struct apply

    {

        // agurt, 10/nov/04: MSVC 6.5 ICE-s on forwarding

        typedef typename mpl::distance<

              typename first<Iter1>::type

            , typename first<Iter2>::type

            >::type type;

    };

};





template<

      typename BOOST_MPL_AUX_NA_PARAM(Sequence1)

    , typename BOOST_MPL_AUX_NA_PARAM(Sequence2)

    >

struct pair_view

{

    typedef nested_begin_end_tag tag;



    typedef typename begin<Sequence1>::type iter1_;

    typedef typename begin<Sequence2>::type iter2_;

    typedef typename min<

          typename iterator_category<iter1_>::type

        , typename iterator_category<iter2_>::type

        >::type category_;

    

    typedef pair_iter<iter1_,iter2_,category_> begin;

    

    typedef pair_iter<

          typename end<Sequence1>::type

        , typename end<Sequence2>::type

        , category_

        > end;

};



BOOST_MPL_AUX_NA_SPEC(2, pair_view)



}}



#endif // BOOST_MPL_PAIR_VIEW_HPP_INCLUDED

