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Open-source constraint solver.
/*
* This file is part of choco-solver, http://choco-solver.org/
*
* Copyright (c) 2022, IMT Atlantique. All rights reserved.
*
* Licensed under the BSD 4-clause license.
*
* See LICENSE file in the project root for full license information.
*/
package org.chocosolver.solver.constraints.extension.binary;
import org.chocosolver.memory.IEnvironment;
import org.chocosolver.memory.IStateInt;
import org.chocosolver.solver.constraints.extension.Tuples;
import org.chocosolver.solver.exception.ContradictionException;
import org.chocosolver.solver.variables.IntVar;
import org.chocosolver.solver.variables.events.IntEventType;
import org.chocosolver.util.objects.setDataStructures.iterable.IntIterableBitSet;
/**
* AC2001 algorithm for binary table constraint
*
*
* @author Charles Prud'homme, Hadrien Cambazard
* @since 08/06/11
*/
public class PropBinAC2001 extends PropBinCSP {
private final IStateInt[] currentSupport0;
private final IStateInt[] currentSupport1;
private final int offset0;
private final int offset1;
private final IntIterableBitSet vrms;
public PropBinAC2001(IntVar x, IntVar y, Tuples tuples) {
this(x, y, new CouplesTable(tuples, x, y));
}
private PropBinAC2001(IntVar x, IntVar y, CouplesTable table) {
super(x, y, table);
offset0 = x.getLB();
offset1 = y.getLB();
currentSupport0 = new IStateInt[x.getUB() - offset0 + 1];
currentSupport1 = new IStateInt[y.getUB() - offset1 + 1];
IEnvironment environment = model.getEnvironment();
for (int i = 0; i < currentSupport0.length; i++) {
currentSupport0[i] = environment.makeInt();
currentSupport0[i].set(-1);
}
for (int i = 0; i < currentSupport1.length; i++) {
currentSupport1[i] = environment.makeInt();
currentSupport1[i].set(-1);
}
vrms = new IntIterableBitSet();
}
@Override
public void propagate(int evtmask) throws ContradictionException {
int support = 0;
boolean found = false;
vrms.clear();
vrms.setOffset(vars[0].getLB());
int ub0 = vars[0].getUB();
for (int val0 = vars[0].getLB(); val0 <= ub0; val0 = vars[0].nextValue(val0)) {
int ub1 = vars[1].getUB();
for (int val1 = vars[1].getLB(); val1 <= ub1; val1 = vars[1].nextValue(val1)) {
if (relation.isConsistent(val0, val1)) {
support = val1;
found = true;
break;
}
}
if (!found) {
vrms.add(val0);
} else
currentSupport0[val0 - offset0].set(support);
found = false;
}
vars[0].removeValues(vrms, this);
found = false;
vrms.clear();
vrms.setOffset(vars[1].getLB());
int ub1 = vars[1].getUB();
for (int val1 = vars[1].getLB(); val1 <= ub1; val1 = vars[1].nextValue(val1)) {
ub0 = vars[0].getUB();
for (int val0 = vars[0].getLB(); val0 <= ub0; val0 = vars[0].nextValue(val0)) {
if (relation.isConsistent(val0, val1)) {
support = val0;
found = true;
break;
}
}
if (!found) {
vrms.add(val1);
} else
currentSupport1[val1 - offset1].set(support);
found = false;
}
vars[1].removeValues(vrms, this);
}
@Override
public void propagate(int idxVarInProp, int mask) throws ContradictionException {
if (IntEventType.isInstantiate(mask)) {
onInstantiationOf(idxVarInProp);
} else {
if (idxVarInProp == 0) {
reviseV1();
} else {
reviseV0();
}
}
}
@Override
public String toString() {
return "Bin_AC2001(" + vars[0].getName() + ", " + vars[1].getName() + ", " + this.relation.getClass().getSimpleName() + ")";
}
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
* updates the support for all values in the domain of v1, and remove unsupported values for v1
*
* @throws ContradictionException
*/
private void reviseV1() throws ContradictionException {
vrms.clear();
vrms.setOffset(vars[1].getLB());
int ub1 = vars[1].getUB();
for (int val1 = vars[1].getLB(); val1 <= ub1; val1 = vars[1].nextValue(val1)) {
if (!vars[0].contains(currentSupport1[val1 - offset1].get())) {
boolean found = false;
int support = currentSupport1[val1 - offset1].get();
int max1 = vars[0].getUB();
while (!found && support < max1) {
support = vars[0].nextValue(support);
if (relation.isConsistent(support, val1)) found = true;
}
if (found) {
currentSupport1[val1 - offset1].set(support);
} else {
vrms.add(val1);
}
}
}
vars[1].removeValues(vrms, this);
}
/**
* updates the support for all values in the domain of v0, and remove unsupported values for v0
*
* @throws ContradictionException
*/
private void reviseV0() throws ContradictionException {
vrms.clear();
vrms.setOffset(vars[0].getLB());
int ub0 = vars[0].getUB();
for (int val0 = vars[0].getLB(); val0 <= ub0; val0 = vars[0].nextValue(val0)) {
if (!vars[1].contains(currentSupport0[val0 - offset0].get())) {
boolean found = false;
int support = currentSupport0[val0 - offset0].get();
int max2 = vars[1].getUB();
while (!found && support < max2) {
support = vars[1].nextValue(support);
if (relation.isConsistent(val0, support)) found = true;
}
if (found)
currentSupport0[val0 - offset0].set(support);
else {
vrms.add(val0);
}
}
}
vars[0].removeValues(vrms, this);
}
private void onInstantiationOf(int idx) throws ContradictionException {
if (idx == 0) {
int value = vars[0].getValue();
vrms.clear();
vrms.setOffset(vars[1].getLB());
int ub1 = vars[1].getUB();
for (int val1 = vars[1].getLB(); val1 <= ub1; val1 = vars[1].nextValue(val1)) {
if (!relation.isConsistent(value, val1)) {
vrms.add(val1);
}
}
vars[1].removeValues(vrms, this);
} else {
int value = vars[1].getValue();
vrms.clear();
vrms.setOffset(vars[0].getLB());
int ub0 = vars[0].getUB();
for (int val0 = vars[0].getLB(); val0 <= ub0; val0 = vars[0].nextValue(val0)) {
if (!relation.isConsistent(val0, value)) {
vrms.add(val0);
}
}
vars[0].removeValues(vrms, this);
}
}
}