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partition.icc

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/*
 *  Main authors:
 *     Guido Tack <tack@gecode.org>
 *     Christian Schulte <schulte@gecode.org>
 *
 *  Contributing authors:
 *     Gabor Szokoli <szokoli@gecode.org>
 *
 *  Copyright:
 *     Guido Tack, 2004
 *     Christian Schulte, 2004
 *     Gabor Szokoli, 2004
 *
 *  Last modified:
 *     $Date: 2006-07-18 15:09:57 +0200 (Tue, 18 Jul 2006) $ by $Author: tack $
 *     $Revision: 3386 $
 *
 *  This file is part of Gecode, the generic constraint
 *  development environment:
 *     http://www.gecode.org
 *
 *  See the file "LICENSE" for information on usage and
 *  redistribution of this file, and for a
 *     DISCLAIMER OF ALL WARRANTIES.
 *
 */

namespace Gecode { namespace Set { namespace RelOp {

  /*
   * "Nary partition" propagator
   *
   */

  template <class View0, class View1>
  forceinline
  PartitionN<View0,View1>::PartitionN(Space* home, ViewArray<View0>& x, View1 y)
    : InhomNaryOnePropagator<View0,PC_SET_ANY,View1,PC_SET_ANY>(home, x, y) {
    shared = x.shared() || viewarrayshared(x,y);
  }

  template <class View0, class View1>
  forceinline
  PartitionN<View0,View1>::PartitionN(Space* home, bool share, PartitionN& p)
    : InhomNaryOnePropagator<View0,PC_SET_ANY,View1,PC_SET_ANY>(home,share,p),
      shared(p.shared) {
    unionOfDets.update(home,p.unionOfDets);
  }

  template <class View0, class View1>
  Actor*
  PartitionN<View0,View1>::copy(Space* home, bool share) {
    return new (home) PartitionN(home,share,*this);
  }

  template <class View0, class View1>
  ExecStatus PartitionN<View0,View1>::post(Space* home, ViewArray<View0>& x,
                                           View1 y) {
    switch (x.size()) {
    case 0:
      GECODE_ME_CHECK(y.cardMax(home, 0));
      return ES_OK;
    case 1:
      return Rel::Eq<View0,View1>::post(home, x[0], y);
    default:
      (void) new (home) PartitionN<View0,View1>(home,x,y);
      return ES_OK;
    }
  }

  template <class View0, class View1>
  PropCost PartitionN<View0,View1>::cost(void) const {
    return PC_QUADRATIC_LO;
  }

  template <class View0, class View1>
  ExecStatus
  PartitionN<View0,View1>::propagate(Space* home) {

    ModEvent me0 = View0::pme(this);
    ModEvent me1 = View1::pme(this);
    bool ubevent = Rel::testSetEventUB(me0, me1);
    bool lbevent = Rel::testSetEventLB(me0, me1);
    bool anybevent = Rel::testSetEventAnyB(me0, me1);
    bool cardevent = Rel::testSetEventCard(me0, me1);

    bool modified = false;
    bool oldModified = false;

    do {
      oldModified = modified;
      modified = false;
      if (oldModified || anybevent)
        GECODE_ME_CHECK(partitionNXiUB(home,modified, x, y,unionOfDets));
      if (modified || oldModified || anybevent)
        GECODE_ME_CHECK(partitionNXiLB(home,modified, x, y,unionOfDets));
      if (modified || oldModified || ubevent)
        GECODE_ME_CHECK(partitionNYUB(home,modified, x, y,unionOfDets));
      if (modified || oldModified || lbevent)
        GECODE_ME_CHECK(partitionNYLB(home,modified, x, y,unionOfDets));
      if (modified || oldModified || ubevent)
        GECODE_ME_CHECK(unionNXiUB(home,modified, x, y,unionOfDets));
      if (modified || oldModified || cardevent)
        GECODE_ME_CHECK(partitionNCard(home,modified, x, y,unionOfDets));
    } while (modified);

    //removing assigned sets from x, accumulating the value:
    for(int i=0;i<x.size();i++){
      //Do not reverse! Eats away the end of the array!
      while (i<x.size() && x[i].assigned()) {
        GlbRanges<View0> det(x[i]);
        unionOfDets.includeI(home,det);
        x.move_lst(i);
      }
    }
    // When we run out of variables, make a final check and disolve:
    if (x.size()==0) {
      BndSetRanges all1(unionOfDets);
      GECODE_ME_CHECK( y.intersectI(home,all1) );
      BndSetRanges all2(unionOfDets);
      GECODE_ME_CHECK( y.includeI(home,all2) );
      unionOfDets.dispose(home);
      return ES_SUBSUMED;
    }

    return shared ? ES_NOFIX : ES_FIX;
  }

}}}

// STATISTICS: set-prop