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hull.cpp

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00001 /* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
00002 /*
00003  *  Main authors:
00004  *     Guido Tack <tack@gecode.org>
00005  *     Christian Schulte <schulte@gecode.org>
00006  *
00007  *  Contributing authors:
00008  *     Gabor Szokoli <szokoli@gecode.org>
00009  *
00010  *  Copyright:
00011  *     Guido Tack, 2004
00012  *     Christian Schulte, 2004
00013  *     Gabor Szokoli, 2004
00014  *
00015  *  Last modified:
00016  *     $Date: 2009-02-04 13:17:26 +0100 (Wed, 04 Feb 2009) $ by $Author: schulte $
00017  *     $Revision: 8137 $
00018  *
00019  *  This file is part of Gecode, the generic constraint
00020  *  development environment:
00021  *     http://www.gecode.org
00022  *
00023  *  Permission is hereby granted, free of charge, to any person obtaining
00024  *  a copy of this software and associated documentation files (the
00025  *  "Software"), to deal in the Software without restriction, including
00026  *  without limitation the rights to use, copy, modify, merge, publish,
00027  *  distribute, sublicense, and/or sell copies of the Software, and to
00028  *  permit persons to whom the Software is furnished to do so, subject to
00029  *  the following conditions:
00030  *
00031  *  The above copyright notice and this permission notice shall be
00032  *  included in all copies or substantial portions of the Software.
00033  *
00034  *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
00035  *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
00036  *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
00037  *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
00038  *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
00039  *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
00040  *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
00041  *
00042  */
00043 
00044 #include <gecode/set/convex.hh>
00045 
00046 namespace Gecode { namespace Set { namespace Convex {
00047 
00048   Actor*
00049   ConvexHull::copy(Space& home, bool share) {
00050     return new (home) ConvexHull(home,share,*this);
00051   }
00052 
00053   ExecStatus
00054   ConvexHull::propagate(Space& home, const ModEventDelta&) {
00055     //x1 is the convex hull of x0
00056 
00057     GECODE_ME_CHECK( x1.cardMin(home,x0.cardMin()) );
00058     GECODE_ME_CHECK( x0.cardMax(home,x1.cardMax()) );
00059 
00060     do {
00061 
00062       //intersect x1 with (x0.lubMin(),x0.lubMax())
00063       //This empties x1 if x0.ub is empty. twice.
00064       GECODE_ME_CHECK( x1.exclude(home,Limits::min,
00065                                   x0.lubMin()-1) );
00066       GECODE_ME_CHECK( x1.exclude(home,x0.lubMax()+1,
00067                                   Limits::max) );
00068 
00069       int minElement = std::min(x1.glbMin(),x0.glbMin());
00070       int maxElement = std::max(x1.glbMax(),x0.glbMax());
00071 
00072       if (minElement<maxElement) {
00073         GECODE_ME_CHECK( x1.include(home, minElement, maxElement));
00074       }
00075 
00076       unsigned int cardMin = x1.cardMin();
00077 
00078       LubRanges<SetView> ubRangeIt(x1);
00079       Iter::Ranges::Cache< LubRanges<SetView> > ubRangeItC(ubRangeIt);
00080       for (;ubRangeItC();++ubRangeItC){
00081         if (ubRangeItC.width() < cardMin
00082             || ubRangeItC.min() > minElement //No need to test for empty lb.
00083             || ubRangeItC.max() < maxElement
00084             ) {
00085           GECODE_ME_CHECK( x1.exclude(home,
00086                                       ubRangeItC.min(), ubRangeItC.max()) );
00087         }
00088       }
00089 
00090       LubRanges<SetView> ubRangeIt2(x1);
00091       GECODE_ME_CHECK(x0.intersectI(home,ubRangeIt2) );
00092 
00093       if (x1.lubMin()!=BndSet::MIN_OF_EMPTY) {
00094         if(x1.lubMin()==x1.glbMin()) {
00095               GECODE_ME_CHECK(x0.include(home,x1.lubMin()));
00096         }
00097         if(x1.lubMax()==x1.glbMax()) {
00098               GECODE_ME_CHECK(x0.include(home,x1.lubMax()));
00099         }
00100       }
00101     } while(x0.assigned()&&!x1.assigned());
00102 
00103     //If x0 is assigned, x1 should be too.
00104     assert(x1.assigned() || !x0.assigned());
00105 
00106     if (x1.assigned()) {
00107       return ES_SUBSUMED(*this,home);
00108     }
00109 
00110     return ES_NOFIX;
00111   }
00112 
00113 }}}
00114 
00115 // STATISTICS: set-prop