org.chocosolver.solver.constraints.binary.PropEqualX_YC Maven / Gradle / Ivy
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/**
* Copyright (c) 2016, Ecole des Mines de Nantes
* All rights reserved.
*
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* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the .
* 4. Neither the name of the nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY ''AS IS'' AND ANY
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package org.chocosolver.solver.constraints.binary;
import org.chocosolver.solver.constraints.Propagator;
import org.chocosolver.solver.constraints.PropagatorPriority;
import org.chocosolver.solver.exception.ContradictionException;
import org.chocosolver.solver.explanations.RuleStore;
import org.chocosolver.solver.variables.IntVar;
import org.chocosolver.solver.variables.delta.IIntDeltaMonitor;
import org.chocosolver.solver.variables.events.IEventType;
import org.chocosolver.solver.variables.events.IntEventType;
import org.chocosolver.util.ESat;
import org.chocosolver.util.procedure.IntProcedure;
/**
* X = Y + C
*
*
*
* @author Charles Prud'homme, Jean-Guillaume Fages
* @since 1 oct. 2010
*/
public final class PropEqualX_YC extends Propagator {
private IntVar x, y;
private final int cste;
// incremental filtering of enumerated domains
private boolean bothEnumerated;
private IIntDeltaMonitor[] idms;
private IntProcedure rem_proc;
private int indexToFilter;
private int offSet;
@SuppressWarnings({"unchecked"})
public PropEqualX_YC(IntVar[] vars, int c) {
super(vars, PropagatorPriority.BINARY, true);
this.x = vars[0];
this.y = vars[1];
this.cste = c;
if (x.hasEnumeratedDomain() && y.hasEnumeratedDomain()) {
bothEnumerated = true;
idms = new IIntDeltaMonitor[2];
idms[0] = vars[0].monitorDelta(this);
idms[1] = vars[1].monitorDelta(this);
rem_proc = i -> vars[indexToFilter].removeValue(i + offSet, this);
}
}
@Override
public int getPropagationConditions(int vIdx) {
if (vars[0].hasEnumeratedDomain() && vars[1].hasEnumeratedDomain())
return IntEventType.all();
else
return IntEventType.boundAndInst();
}
@Override
public void propagate(int evtmask) throws ContradictionException {
updateBounds();
// ensure that, in case of enumerated domains, holes are also propagated
if (bothEnumerated) {
int ub = x.getUB();
for (int val = x.getLB(); val <= ub; val = x.nextValue(val)) {
if (!y.contains(val - cste)) {
x.removeValue(val, this);
}
}
ub = y.getUB();
for (int val = y.getLB(); val <= ub; val = y.nextValue(val)) {
if (!x.contains(val + cste)) {
y.removeValue(val, this);
}
}
idms[0].unfreeze();
idms[1].unfreeze();
}
if (x.isInstantiated()) {
assert (y.isInstantiated());
setPassive();
}
}
@Override
public void propagate(int varIdx, int mask) throws ContradictionException {
updateBounds();
if (x.isInstantiated()) {
assert (y.isInstantiated());
setPassive();
} else if (bothEnumerated) {
if (varIdx == 0) {
indexToFilter = 1;
offSet = -cste;
} else {
indexToFilter = 0;
offSet = cste;
}
idms[varIdx].freeze();
idms[varIdx].forEachRemVal(rem_proc);
idms[varIdx].unfreeze();
}
}
@SuppressWarnings("StatementWithEmptyBody")
private void updateBounds() throws ContradictionException {
while (x.updateLowerBound(y.getLB() + cste, this) | y.updateLowerBound(x.getLB() - cste, this)) ;
while (x.updateUpperBound(y.getUB() + cste, this) | y.updateUpperBound(x.getUB() - cste, this)) ;
}
@Override
public ESat isEntailed() {
if ((x.getUB() < y.getLB() + cste) ||
(x.getLB() > y.getUB() + cste) ||
x.hasEnumeratedDomain() && y.hasEnumeratedDomain() && !match())
return ESat.FALSE;
else if (x.isInstantiated() &&
y.isInstantiated() &&
(x.getValue() == y.getValue() + cste))
return ESat.TRUE;
else
return ESat.UNDEFINED;
}
private boolean match() {
int lb = x.getLB();
int ub = x.getUB();
for (; lb <= ub; lb = x.nextValue(lb)) {
if (y.contains(lb - cste)) return true;
}
return false;
}
@Override
public boolean why(RuleStore ruleStore, IntVar var, IEventType evt, int value) {
boolean newrules = ruleStore.addPropagatorActivationRule(this);
if (var.equals(x)) {
IntEventType ievt = (IntEventType) evt;
switch (ievt) {
case REMOVE:
newrules |= ruleStore.addRemovalRule(y, value - cste);
break;
case DECUPP:
newrules |= ruleStore.addUpperBoundRule(y);
break;
case INCLOW:
newrules |= ruleStore.addLowerBoundRule(y);
break;
case INSTANTIATE:
newrules |= ruleStore.addFullDomainRule(y);
break;
default: break;// nothing to do
}
} else if (var.equals(y)) {
IntEventType ievt = (IntEventType) evt;
switch (ievt) {
case REMOVE:
newrules |= ruleStore.addRemovalRule(x, value + cste);
break;
case DECUPP:
newrules |= ruleStore.addUpperBoundRule(x);
break;
case INCLOW:
newrules |= ruleStore.addLowerBoundRule(x);
break;
case INSTANTIATE:
newrules |= ruleStore.addFullDomainRule(x);
break;
default: break;// nothing to do
}
} else {
newrules |= super.why(ruleStore, var, evt, value);
}
return newrules;
}
@Override
public String toString() {
StringBuilder bf = new StringBuilder();
bf.append("prop(").append(vars[0].getName()).append(".EQ.").append(vars[1].getName());
if (cste != 0) {
bf.append("+").append(cste);
}
bf.append(")");
return bf.toString();
}
}