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Filename : interval_subset_comparer.hpp
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/*-----------------------------------------------------------------------------+
Copyright (c) 2008-2009: Joachim Faulhaber
+------------------------------------------------------------------------------+
   Distributed under the Boost Software License, Version 1.0.
      (See accompanying file LICENCE.txt or copy at
           http://www.boost.org/LICENSE_1_0.txt)
+-----------------------------------------------------------------------------*/
#ifndef BOOST_ICL_INTERVAL_SUBSET_COMPARER_HPP_JOFA_090827
#define BOOST_ICL_INTERVAL_SUBSET_COMPARER_HPP_JOFA_090827

#include <boost/icl/type_traits/is_map.hpp>
#include <boost/icl/detail/notate.hpp>
#include <boost/icl/detail/relation_state.hpp>
#include <boost/icl/type_traits/identity_element.hpp>
#include <boost/icl/type_traits/is_concept_equivalent.hpp>
#include <boost/icl/type_traits/is_interval_container.hpp>
#include <boost/icl/type_traits/is_set.hpp>
#include <boost/icl/concept/interval_set_value.hpp>

namespace boost{namespace icl
{

#ifdef BOOST_MSVC 
#pragma warning(push)
#pragma warning(disable:4127) // conditional expression is constant
#endif                        

namespace Interval_Set
{

//------------------------------------------------------------------------------
template<class LeftT, class RightT>
struct settic_codomain_compare
{
    static int apply(typename LeftT::const_iterator& left_, typename RightT::const_iterator& right_)
    {
        return inclusion_compare( icl::co_value<LeftT>(left_), 
                                 icl::co_value<RightT>(right_));
    }
};

template<class LeftT, class RightT>
struct atomic_codomain_compare
{
    static int apply(typename LeftT::const_iterator& left_, typename RightT::const_iterator& right_)
    {
        if(icl::co_value<LeftT>(left_) == icl::co_value<RightT>(right_))
            return inclusion::equal;
        else
            return inclusion::unrelated;
    }
};

template<class LeftT, class RightT>
struct empty_codomain_compare
{
    static int apply(typename LeftT::const_iterator&, typename RightT::const_iterator)
    {
        return inclusion::equal;
    }
};

template<class LeftT, class RightT>
struct map_codomain_compare
{
    static int apply(typename LeftT::const_iterator& left_, typename RightT::const_iterator& right_)
    {
        using namespace boost::mpl;
        typedef typename LeftT::codomain_type  LeftCodomainT;
        typedef typename RightT::codomain_type RightCodomainT;

        return
            if_<
                bool_<is_concept_equivalent<is_set,LeftCodomainT,
                                                   RightCodomainT>::value>,
                settic_codomain_compare<LeftT,RightT>,
                atomic_codomain_compare<LeftT,RightT>
            >
            ::type::apply(left_, right_);
    }
};


//------------------------------------------------------------------------------
template<class LeftT, class RightT>
class subset_comparer
{
private:
    subset_comparer& operator = (const subset_comparer&);
public:
    typedef typename LeftT::const_iterator  LeftIterT;
    typedef typename RightT::const_iterator RightIterT;

    BOOST_STATIC_CONSTANT(bool, 
        _compare_codomain = (mpl::and_<is_map<LeftT>, is_map<RightT> >::value)); 


    subset_comparer(const LeftT&      left,
                    const RightT&     right,
                    const LeftIterT&  left_end,
                    const RightIterT& right_end)
        : _left(left), _right(right),
          _left_end(left_end), _right_end(right_end), _result(equal)
    {}

    enum{nextboth, nextleft, nextright, stop};

    enum
    {
        unrelated  = inclusion::unrelated, 
        subset     = inclusion::subset,     // left is_subset_of   right 
        superset   = inclusion::superset,   // left is_superset_of right
        equal      = inclusion::equal       // equal = subset | superset
    };

    int result()const{ return _result; }


    int co_compare(LeftIterT& left, RightIterT& right)
    {
        using namespace boost::mpl;

        return  
            if_<
                bool_<is_concept_equivalent<is_interval_map,LeftT,RightT>::value>,
                map_codomain_compare<LeftT,RightT>,
                empty_codomain_compare<LeftT,RightT>
            >
            ::type::apply(left,right);
    }

    int restrict_result(int state) { return _result &= state; }

    int proceed(LeftIterT& left, RightIterT& right)
    {
        if(upper_less(key_value<LeftT>(left), key_value<RightT>(right)))
        {   // left  ..)  
            // right .....)
            _prior_left = left;
            ++left;
            return nextleft;
        }
        else if(upper_less(key_value<RightT>(right), key_value<LeftT>(left)))
        {   // left  .....)
            // right ..)
            _prior_right = right;
            ++right;
            return nextright;
        }
        else//key_value<LeftT>(left).upper_equal(key_value<RightT>(right))
        {   // left  ..)
            // right ..)
            ++left; 
            ++right;    
            return nextboth;
        }
    }

    int next_both(LeftIterT& left, RightIterT& right)
    {
        if(left == _left_end && right == _right_end)
            return stop;
        else if(left == _left_end)
        {   // left: ....end    left could be subset
            // right:....[..
            restrict_result(subset);
            return stop;
        }
        else if(right == _right_end)
        {   // left: ....[..    left could be superset
            // right:....end
            restrict_result(superset);
            return stop;
        }
        else if(exclusive_less(key_value<LeftT>(left), key_value<RightT>(right)))
        {   // left: [..) . . .[---)      left could be superset
            // right:           [..)....  if [---) exists
            restrict_result(superset);
            if(unrelated == _result)
                return stop;
            else
            {
                LeftIterT joint_ = _left.lower_bound(key_value<RightT>(right));
                if(joint_ == _left.end())
                {
                    _result = unrelated;
                    return stop;
                }
                else
                {
                    left = joint_;
                    return nextboth;
                }
            }
        }
        else if(exclusive_less(key_value<RightT>(right), key_value<LeftT>(left)))
        {   // left:             [..  left could be subset
            // right:....) . . .[---) if [---) exists 
            restrict_result(subset);
            if(unrelated == _result)
                return stop;
            else
            {
                RightIterT joint_ = _right.lower_bound(key_value<LeftT>(left));
                if(joint_ == _right.end())
                {
                    _result = unrelated;
                    return stop;
                }
                else
                {
                    right = joint_;
                    return nextboth;
                }
            }
        }

        // left and right have intervals with nonempty intersection:
        if(_compare_codomain)
            if(unrelated == restrict_result(co_compare(left,right)))
                return stop;

        // examine left borders only. Right borders are checked in proceed
        if(lower_less(key_value<LeftT>(left), key_value<RightT>(right)))
        {   // left: ....[...     left could be superset
            // right:....   [..
            if(unrelated == restrict_result(superset))
                return stop;
        }
        else if(lower_less(key_value<RightT>(right), key_value<LeftT>(left)))
        {   // left: ....   [..   left can be subset
            // right:....[...
            if(unrelated == restrict_result(subset))
                return stop;
        }
        //else key_value<LeftT>(right).lower_equal(key_value<RightT>(left))
            // left: ....[..   both can be equal
            // right:....[..
            // nothing to do: proceed

        return proceed(left, right);
    }

    int next_left(LeftIterT& left, RightIterT& right)
    {
        if(left == _left_end)
        {   // left: ..)end    left could be subset
            // right:......)
            restrict_result(subset);
            return stop;            
        }
        else if(!touches(key_value<LeftT>(_prior_left), key_value<LeftT>(left)))
        {   // left: ..)   [..
            // right:.........)
            if(lower_less(key_value<RightT>(right), key_value<LeftT>(left)))
            {   //   ..)   [..   left could be subset
                //   ..........)
                if(unrelated == restrict_result(subset))
                    return stop;            
            }
            //else   ..)   [...
            //          [..
            if(_compare_codomain && intersects(key_value<LeftT>(left),key_value<RightT>(right)) )
                if(unrelated == restrict_result(co_compare(left,right)))
                    return stop;
        }
        else
        {   // left: ..)[..  left could be subset
            // right:.......)
            if(_compare_codomain && intersects(key_value<LeftT>(left), key_value<RightT>(right)) )
                if(unrelated == restrict_result(co_compare(left,right)))
                    return stop;
        }

        return proceed(left, right);
    }


    int next_right(LeftIterT& left, RightIterT& right)
    {
        if(right == _right_end)
        {   // left: ......)    left could be superset
            // right:..)end
            restrict_result(superset);
            return stop;            
        }
        else if(!touches(key_value<RightT>(_prior_right), key_value<RightT>(right)))
        {   // left: .........)
            // right:..)   [..
            if(lower_less(key_value<LeftT>(left), key_value<RightT>(right)))
            {   //       [....)  left could be superset
                //   ..)   [..
                if(unrelated == restrict_result(superset))
                    return stop;            
            }
            //else       [....)
            //   ..)   [..
            if(_compare_codomain && intersects(key_value<LeftT>(left), key_value<RightT>(right)) )
                if(unrelated == restrict_result(co_compare(left,right)))
                    return stop;
        }
        else
        {
            if(_compare_codomain && intersects(key_value<LeftT>(left), key_value<RightT>(right)) )
                if(unrelated == restrict_result(co_compare(left,right)))
                    return stop;
        }

        return proceed(left, right);
    }

private:
    const LeftT&  _left;
    const RightT& _right;
    LeftIterT     _left_end;
    RightIterT    _right_end;
    LeftIterT     _prior_left;
    RightIterT    _prior_right;
    int           _result;
};





//------------------------------------------------------------------------------
// Subset/superset comparison on ranges of two interval container 
//------------------------------------------------------------------------------
template<class LeftT, class RightT>
int subset_compare
(
    const LeftT& left,   //sub
    const RightT& right, //super
    typename LeftT::const_iterator  left_begin,   
    typename LeftT::const_iterator  left_end,
    typename RightT::const_iterator right_begin, 
    typename RightT::const_iterator right_end
)
{
    typedef subset_comparer<LeftT,RightT> Step;
    Step step(left, right, left_end, right_end);

    typename LeftT::const_iterator  left_  = left_begin;
    typename RightT::const_iterator right_ = right_begin;

    int state = Step::nextboth;
    while(state != Step::stop)
    {
        switch(state){
        case Step::nextboth:    state = step.next_both(left_, right_);  break;
        case Step::nextleft:    state = step.next_left(left_, right_);  break;
        case Step::nextright:   state = step.next_right(left_, right_); break;
        }
    }
    return step.result();
}


} // namespace Interval_Set
    
#ifdef BOOST_MSVC
#pragma warning(pop)
#endif

}} // namespace icl boost

#endif