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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.solver.constraints.extension.Tuples;
import org.chocosolver.solver.exception.ContradictionException;
import org.chocosolver.solver.exception.SolverException;
import org.chocosolver.solver.variables.IntVar;
import org.chocosolver.solver.variables.events.IntEventType;
import org.chocosolver.solver.variables.events.PropagatorEventType;
import org.chocosolver.util.iterators.DisposableValueIterator;
/**
* AC3 bit rm algorithm for binary table constraint
*
*
* @author Charles Prud'homme, Hadrien Cambazard
* @since 22/04/2014
*/
public class PropBinAC3bitrm extends PropBinCSP {
private int offset0;
private int offset1;
private int minS0; //value with minimum number of supports for v0
private int minS1; //value with minimum number of supports for v1
private int initDomSize0;
private int initDomSize1;
public PropBinAC3bitrm(IntVar x, IntVar y, Tuples tuples) {
this(x, y, new CouplesBitSetTable(tuples, x, y));
if(!x.hasEnumeratedDomain() || !y.hasEnumeratedDomain()) {
throw new SolverException("PropBinAC3bitrm (\"AC3bit+rm\")may produce incorrect filtering with bounded variables");
}
offset0 = v0.getLB();
offset1 = v1.getLB();
initDomSize0 = v0.getUB() - offset0 + 1;
initDomSize1 = v1.getUB() - offset1 + 1;
}
private PropBinAC3bitrm(IntVar x, IntVar y, CouplesBitSetTable table) {
super(x, y, table);
offset0 = v0.getLB();
offset1 = v1.getLB();
initDomSize0 = v0.getUB() - offset0 + 1;
initDomSize1 = v1.getUB() - offset1 + 1;
}
@Override
public void propagate(int evtmask) throws ContradictionException {
if (PropagatorEventType.isFullPropagation(evtmask)) {
fastInitNbSupports();
DisposableValueIterator itv0 = v0.getValueIterator(true);
try {
while (itv0.hasNext()) {
int val0 = itv0.next();
if (((CouplesBitSetTable) relation).checkUnsupportedValue(0, val0, v1)) {
v0.removeValue(val0, this);
}
}
} finally {
itv0.dispose();
}
itv0 = v1.getValueIterator(true);
try {
while (itv0.hasNext()) {
int val1 = itv0.next();
if (((CouplesBitSetTable) relation).checkUnsupportedValue(1, val1, v0)) {
v1.removeValue(val1, this);
}
}
} finally {
itv0.dispose();
}
}
reviseV0();
reviseV1();
}
@Override
public void propagate(int idxVarInProp, int mask) throws ContradictionException {
if (IntEventType.isInstantiate(mask)) {
onInstantiationOf(idxVarInProp);
} else if (idxVarInProp == 0) {
reviseV1();
} else {
reviseV0();
}
}
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
private void fastInitNbSupports() {
int[] initS1 = new int[initDomSize1];
minS0 = Integer.MAX_VALUE;
minS1 = Integer.MAX_VALUE;
DisposableValueIterator itv0 = v0.getValueIterator(true);
while (itv0.hasNext()) {
int val0 = itv0.next();
int initS0 = 0;
DisposableValueIterator itv1 = v1.getValueIterator(true);
while (itv1.hasNext()) {
int val1 = itv1.next();
if (relation.isConsistent(val0, val1)) {
initS0++;
initS1[val1 - offset1]++;
}
}
if (initS0 < minS0) minS0 = initS0;
itv1.dispose();
}
itv0.dispose();
for (int i = 0; i < initS1.length; i++) {
if (initS1[i] < minS1) minS1 = initS1[i];
}
}
/**
* updates the support for all values in the domain of v1, and remove unsupported values for v1
*/
private void reviseV1() throws ContradictionException {
int v0Size = v0.getDomainSize();
if (minS1 <= (initDomSize0 - v0Size)) {
DisposableValueIterator itv1 = v1.getValueIterator(true);
try {
while (itv1.hasNext()) {
int y = itv1.next();
if (((CouplesBitSetTable) relation).checkUnsupportedValue(1, y, v0)) {
v1.removeValue(y, this);
}
}
} finally {
itv1.dispose();
}
}
}
/**
* updates the support for all values in the domain of v0, and remove unsupported values for v0
*/
private void reviseV0() throws ContradictionException {
int v1Size = v1.getDomainSize();
if (minS0 <= (initDomSize1 - v1Size)) {
DisposableValueIterator itv0 = v0.getValueIterator(true);
try {
while (itv0.hasNext()) {
int x = itv0.next();
if (((CouplesBitSetTable) relation).checkUnsupportedValue(0, x, v1)) {
v0.removeValue(x, this);
}
}
} finally {
itv0.dispose();
}
}
}
private void onInstantiationOf(int idx) throws ContradictionException {
if (idx == 0) {
int value = v0.getValue();
DisposableValueIterator itv1 = v1.getValueIterator(true);
try {
while (itv1.hasNext()) {
int val = itv1.next();
if (!relation.isConsistent(value, val)) {
v1.removeValue(val, this);
}
}
} finally {
itv1.dispose();
}
} else {
int value = v1.getValue();
DisposableValueIterator itv0 = v0.getValueIterator(true);
try {
while (itv0.hasNext()) {
int val = itv0.next();
if (!relation.isConsistent(val, value)) {
v0.removeValue(val, this);
}
}
} finally {
itv0.dispose();
}
}
}
}