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Open-source constraint solver.
/**
* This file is part of choco-solver, http://choco-solver.org/
*
* Copyright (c) 2018, 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 gnu.trove.list.array.TIntArrayList;
import org.chocosolver.solver.constraints.Propagator;
import org.chocosolver.solver.constraints.PropagatorPriority;
import org.chocosolver.solver.exception.ContradictionException;
import org.chocosolver.solver.variables.IntVar;
import org.chocosolver.solver.variables.SetVar;
import org.chocosolver.solver.variables.Variable;
import org.chocosolver.util.ESat;
import org.chocosolver.util.objects.setDataStructures.ISetIterator;
import org.chocosolver.util.tools.ArrayUtils;
/**
* Propagator for element constraint over sets
* states that
* array[index-offSet] = set
*
* @author Jean-Guillaume Fages
*/
public class PropElement extends Propagator {
//***********************************************************************************
// VARIABLES
//***********************************************************************************
private TIntArrayList constructiveDisjunction;
private IntVar index;
private SetVar set;
private SetVar[] array;
private int offSet;
//***********************************************************************************
// CONSTRUCTORS
//***********************************************************************************
/**
* Propagator for element constraint over sets
* states that array[index-offSet] = set
*
* @param index integer variable
* @param array array of set variables
* @param offSet int
* @param set set variable
*/
public PropElement(IntVar index, SetVar[] array, int offSet, SetVar set) {
super(ArrayUtils.append(array, new Variable[]{set, index}), PropagatorPriority.LINEAR, false);
this.index = (IntVar) vars[vars.length - 1];
this.set = (SetVar) vars[vars.length - 2];
this.array = new SetVar[array.length];
for (int i = 0; i < array.length; i++) {
this.array[i] = (SetVar) vars[i];
}
this.offSet = offSet;
constructiveDisjunction = new TIntArrayList();
}
//***********************************************************************************
// METHODS
//***********************************************************************************
@Override
public void propagate(int evtmask) throws ContradictionException {
index.updateBounds(offSet, array.length - 1 + offSet, this);
if (index.isInstantiated()) {
// filter set and array
setEq(set, array[index.getValue() - offSet]);
setEq(array[index.getValue() - offSet], set);
} else {
// filter index
int ub = index.getUB();
boolean noEmptyKer = true;
for (int i = index.getLB(); i <= ub; i = index.nextValue(i)) {
if (disjoint(set, array[i - offSet]) || disjoint(array[i - offSet], set)) {// array[i] != set
index.removeValue(i, this);
} else {
if (array[i - offSet].getLB().size() == 0) {
noEmptyKer = false;
}
}
}
ub = index.getUB();
// filter set (constructive disjunction)
if (noEmptyKer) {// from ker
constructiveDisjunction.clear();
ISetIterator iter = array[index.getLB() - offSet].getLB().iterator();
while (iter.hasNext()){
int j = iter.nextInt();
if (!set.getLB().contains(j)) {
constructiveDisjunction.add(j);
}
}
for (int cd = constructiveDisjunction.size() - 1; cd >= 0; cd--) {
int j = constructiveDisjunction.get(cd);
for (int i = index.nextValue(index.getLB()); i <= ub; i = index.nextValue(i)) {
if (!array[i - offSet].getLB().contains(j)) {
constructiveDisjunction.remove(j);
break;
}
}
}
for (int cd = constructiveDisjunction.size() - 1; cd >= 0; cd--) {
int j = constructiveDisjunction.get(cd);
set.force(j, this);
}
}
if (!set.isInstantiated()) {// from env
ISetIterator iter = set.getUB().iterator();
while (iter.hasNext()){
int j = iter.nextInt();
boolean valueExists = false;
for (int i = index.getLB(); i <= ub; i = index.nextValue(i)) {
if (array[i - offSet].getUB().contains(j)) {
valueExists = true;
break;
}
}
if (!valueExists) {
set.remove(j, this);
}
}
}
}
}
private void setEq(SetVar s1, SetVar s2) throws ContradictionException {
ISetIterator iter = s2.getLB().iterator();
while (iter.hasNext()){
s1.force(iter.nextInt(), this);
}
iter = s1.getUB().iterator();
while (iter.hasNext()){
int j = iter.nextInt();
if (!s2.getUB().contains(j)) {
s1.remove(j, this);
}
}
}
private boolean disjoint(SetVar s1, SetVar s2) {
ISetIterator iter = s2.getLB().iterator();
while (iter.hasNext()){
if (!s1.getUB().contains(iter.nextInt())) {
return true;
}
}
return false;
}
@Override
public ESat isEntailed() {
if (index.isInstantiated()) {
int i = index.getValue() - offSet;
if (i < 0 || i >= array.length || disjoint(set, array[i]) || disjoint(array[i], set)) {
return ESat.FALSE;
} else {
if (set.isInstantiated() && array[i].isInstantiated()) {
return ESat.TRUE;
} else {
return ESat.UNDEFINED;
}
}
}
return ESat.UNDEFINED;
}
}