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Open-source constraint solver.
/*
* This file is part of choco-solver, http://choco-solver.org/
*
* Copyright (c) 2020, IMT Atlantique. All rights reserved.
*
* Licensed under the BSD 4-clause license.
*
* See LICENSE file in the project root for full license information.
*/
/**
* Created by IntelliJ IDEA.
* User: Jean-Guillaume Fages
* Date: 14/01/13
* Time: 16:36
*/
package org.chocosolver.solver.constraints.set;
import org.chocosolver.solver.constraints.Propagator;
import org.chocosolver.solver.constraints.PropagatorPriority;
import org.chocosolver.solver.exception.ContradictionException;
import org.chocosolver.solver.variables.SetVar;
import org.chocosolver.solver.variables.delta.ISetDeltaMonitor;
import org.chocosolver.solver.variables.events.PropagatorEventType;
import org.chocosolver.solver.variables.events.SetEventType;
import org.chocosolver.util.ESat;
import org.chocosolver.util.objects.setDataStructures.ISetIterator;
import org.chocosolver.util.procedure.IntProcedure;
import org.chocosolver.util.tools.ArrayUtils;
public class PropUnion extends Propagator {
//***********************************************************************************
// VARIABLES
//***********************************************************************************
private int k;
private ISetDeltaMonitor[] sdm;
private IntProcedure unionForced, unionRemoved, setForced, setRemoved;
//***********************************************************************************
// CONSTRUCTORS
//***********************************************************************************
/**
* The union of sets is equal to union
*
* @param sets set variables to unify
* @param union resulting set variable
*/
public PropUnion(SetVar[] sets, SetVar union) {
super(ArrayUtils.append(sets, new SetVar[]{union}), PropagatorPriority.LINEAR, true);
k = sets.length;
sdm = new ISetDeltaMonitor[k + 1];
for (int i = 0; i <= k; i++) {
sdm[i] = this.vars[i].monitorDelta(this);
}
// PROCEDURES
unionForced = element -> {
int mate = -1;
for (int i = 0; i < k && mate != -2; i++) {
if (vars[i].getUB().contains(element)) {
if (mate == -1) {
mate = i;
} else {
mate = -2;
}
}
}
if (mate == -1) {
fails(); // TODO: could be more precise, for explanation purpose
} else if (mate != -2) {
vars[mate].force(element, this);
}
};
unionRemoved = element -> {
for (int i = 0; i < k; i++) {
vars[i].remove(element, this);
}
};
setForced = element -> vars[k].force(element, this);
setRemoved = element -> {
if (vars[k].getUB().contains(element)) {
int mate = -1;
for (int i = 0; i < k && mate != -2; i++) {
if (vars[i].getUB().contains(element)) {
if (mate == -1) {
mate = i;
} else {
mate = -2;
}
}
}
if (mate == -1) {
vars[k].remove(element, this);
} else if (mate != -2 && vars[k].getLB().contains(element)) {
vars[mate].force(element, this);
}
}
};
}
//***********************************************************************************
// METHODS
//***********************************************************************************
@Override
public void propagate(int evtmask) throws ContradictionException {
if (PropagatorEventType.isFullPropagation(evtmask)) {
SetVar union = vars[k];
for (int i = 0; i < k; i++) {
ISetIterator iter = vars[i].getLB().iterator();
while(iter.hasNext())
union.force(iter.nextInt(),this);
iter = vars[i].getUB().iterator();
while(iter.hasNext()) {
int j = iter.nextInt();
if (!union.getUB().contains(j))
vars[i].remove(j, this);
}
}
ISetIterator unionUB = union.getUB().iterator();
while (unionUB.hasNext()) {
int j = unionUB.nextInt();
if (union.getLB().contains(j)) {
int mate = -1;
for (int i = 0; i < k && mate != -2; i++) {
if (vars[i].getUB().contains(j)) {
if (mate == -1) {
mate = i;
} else {
mate = -2;
}
}
}
if (mate == -1) {
fails(); // TODO: could be more precise, for explanation purpose
} else if (mate != -2) {
vars[mate].force(j, this);
}
} else {
int mate = -1;
for (int i = 0; i < k; i++) {
if (vars[i].getUB().contains(j)) {
mate = i;
break;
}
}
if (mate == -1) union.remove(j, this);
}
}
// ------------------
for (int i = 0; i <= k; i++)
sdm[i].unfreeze();
}
}
@Override
public void propagate(int idxVarInProp, int mask) throws ContradictionException {
sdm[idxVarInProp].freeze();
if (idxVarInProp < k) {
sdm[idxVarInProp].forEach(setForced, SetEventType.ADD_TO_KER);
sdm[idxVarInProp].forEach(setRemoved, SetEventType.REMOVE_FROM_ENVELOPE);
} else {
sdm[idxVarInProp].forEach(unionForced, SetEventType.ADD_TO_KER);
sdm[idxVarInProp].forEach(unionRemoved, SetEventType.REMOVE_FROM_ENVELOPE);
}
sdm[idxVarInProp].unfreeze();
}
@Override
public ESat isEntailed() {
for (int i = 0; i < k; i++) {
for (int j : vars[i].getLB())
if (!vars[k].getUB().contains(j))
return ESat.FALSE;
}
for (int j : vars[k].getLB()) {
int mate = -1;
for (int i = 0; i < k; i++)
if (vars[i].getUB().contains(j)) {
mate = i;
break;
}
if (mate == -1) return ESat.FALSE;
}
if (isCompletelyInstantiated()) return ESat.TRUE;
return ESat.UNDEFINED;
}
}