hull.cc

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/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
/*
 *  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: 2008-02-06 18:48:22 +0100 (Wed, 06 Feb 2008) $ by $Author: schulte $
 *     $Revision: 6102 $
 *
 *  This file is part of Gecode, the generic constraint
 *  development environment:
 *     http://www.gecode.org
 *
 *  Permission is hereby granted, free of charge, to any person obtaining
 *  a copy of this software and associated documentation files (the
 *  "Software"), to deal in the Software without restriction, including
 *  without limitation the rights to use, copy, modify, merge, publish,
 *  distribute, sublicense, and/or sell copies of the Software, and to
 *  permit persons to whom the Software is furnished to do so, subject to
 *  the following conditions:
 *
 *  The above copyright notice and this permission notice shall be
 *  included in all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */

#include "gecode/set/convex.hh"

namespace Gecode { namespace Set { namespace Convex {

  Actor*
  ConvexHull::copy(Space* home, bool share) {
    return new (home) ConvexHull(home,share,*this);
  }

  Support::Symbol
  ConvexHull::ati(void) {
    return Support::Symbol("Gecode::Set::Convex::ConvexHull");
  }

  Reflection::ActorSpec
  ConvexHull::spec(const Space* home, Reflection::VarMap& m) const {
    return BinaryPropagator<SetView,PC_SET_ANY>::spec(home, m, ati());
  }

  ExecStatus
  ConvexHull::propagate(Space* home, ModEventDelta) {
    //x1 is the convex hull of x0

    GECODE_ME_CHECK( x1.cardMin(home,x0.cardMin()) );
    GECODE_ME_CHECK( x0.cardMax(home,x1.cardMax()) );

    do {

      //intersect x1 with (x0.lubMin(),x0.lubMax())
      //This empties x1 if x0.ub is empty. twice.
      GECODE_ME_CHECK( x1.exclude(home,Limits::min,
                                  x0.lubMin()-1) );
      GECODE_ME_CHECK( x1.exclude(home,x0.lubMax()+1,
                                  Limits::max) );

      int minElement = std::min(x1.glbMin(),x0.glbMin());
      int maxElement = std::max(x1.glbMax(),x0.glbMax());

      if (minElement<maxElement) {
        GECODE_ME_CHECK( x1.include(home, minElement, maxElement));
      }

      unsigned int cardMin = x1.cardMin();

      LubRanges<SetView> ubRangeIt(x1);
      Iter::Ranges::Cache< LubRanges<SetView> > ubRangeItC(ubRangeIt);
      for (;ubRangeItC();++ubRangeItC){
        if (ubRangeItC.width() < cardMin
            || ubRangeItC.min() > minElement //No need to test for empty lb.
            || ubRangeItC.max() < maxElement
            ) {
          GECODE_ME_CHECK( x1.exclude(home,
                                      ubRangeItC.min(), ubRangeItC.max()) );
        }
      }

      LubRanges<SetView> ubRangeIt2(x1);
      GECODE_ME_CHECK(x0.intersectI(home,ubRangeIt2) );

      if (x1.lubMin()!=BndSet::MIN_OF_EMPTY) {
        if(x1.lubMin()==x1.glbMin()) {
              GECODE_ME_CHECK(x0.include(home,x1.lubMin()));
        }
        if(x1.lubMax()==x1.glbMax()) {
              GECODE_ME_CHECK(x0.include(home,x1.lubMax()));
        }
      }
    } while(x0.assigned()&&!x1.assigned());
    
    //If x0 is assigned, x1 should be too.
    assert(x1.assigned() || !x0.assigned());

    if (x1.assigned()) {
      return ES_SUBSUMED(this,home);
    }

    return ES_NOFIX;
  }

  void
  ConvexHull::post(Space* home, Reflection::VarMap& vars,
               const Reflection::ActorSpec& spec) {
    spec.checkArity(2);
    SetView s0(home, vars, spec[0]);
    SetView s1(home, vars, spec[1]);
    (void) new (home) ConvexHull(home,s0,s1);
  }

}}

namespace {
  GECODE_REGISTER1(Set::Convex::ConvexHull);
}

}

// STATISTICS: set-prop