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Open-source constraint solver.
/*
* This file is part of choco-solver, http://choco-solver.org/
*
* Copyright (c) 2023, 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.variables.view.set;
import org.chocosolver.solver.ICause;
import org.chocosolver.solver.exception.ContradictionException;
import org.chocosolver.solver.variables.BoolVar;
import org.chocosolver.solver.variables.delta.ISetDelta;
import org.chocosolver.solver.variables.delta.ISetDeltaMonitor;
import org.chocosolver.solver.variables.delta.SetDelta;
import org.chocosolver.solver.variables.delta.monitor.SetDeltaMonitor;
import org.chocosolver.solver.variables.events.IEventType;
import org.chocosolver.solver.variables.events.SetEventType;
import org.chocosolver.solver.variables.view.SetView;
import org.chocosolver.util.objects.setDataStructures.ISet;
import org.chocosolver.util.objects.setDataStructures.SetFactory;
import org.chocosolver.util.objects.setDataStructures.SetType;
import java.util.Arrays;
/**
* Set view over an array of boolean variables defined such that:
* boolVars[x - offset] = True <=> x in setView
* This view is equivalent to the {@link org.chocosolver.solver.constraints.set.PropBoolChannel} constraint.
*
* @author Dimitri Justeau-Allaire
* @since 03/2021
*/
public class SetBoolsView extends SetView {
/**
* Offset between boolVars array indices and set elements
*/
private final int offset;
/**
* Internal bounds only updated by the view.
*/
private final ISet lb;
private final ISet ub;
protected boolean reactOnModification;
private ISetDelta delta;
/**
* Instantiate an set view over an array of boolean variables such that:
* boolVars[x - offset] = True <=> x in setView
*
* @param name name of the variable
* @param offset Offset between boolVars array indices and set elements
* @param variables observed variables
*/
protected SetBoolsView(String name, int offset, B... variables) {
super(name, variables);
this.offset = offset;
this.lb = SetFactory.makeStoredSet(SetType.BITSET, 0, variables[0].getModel());
this.ub = SetFactory.makeStoredSet(SetType.BITSET, 0, variables[0].getModel());
// init bounds
for (int i = 0; i < variables.length; i++) {
if (variables[i].isInstantiatedTo(BoolVar.kTRUE)) {
lb.add(i + offset);
}
if (variables[i].contains(BoolVar.kTRUE)) {
ub.add(i + offset);
}
}
}
/**
* Instantiate an set view over an array of boolean variables such that:
* boolVars[x - offset] = True <=> x in setView
*
* @param offset Offset between boolVars array indices and set elements
* @param variables observed variables
*/
@SuppressWarnings("unchecked")
public SetBoolsView(int offset, B... variables) {
this("BOOLS_SET_VIEW["
+ String.join(",", Arrays.stream(variables)
.map(i -> i.getName())
.toArray(String[]::new))
+ "]",
offset, variables);
}
@Override
protected boolean doRemoveSetElement(int element) throws ContradictionException {
if (getVariables()[element - this.offset].instantiateTo(BoolVar.kFALSE, this)) {
ub.remove(element);
if (reactOnModification) {
delta.add(element, SetDelta.UB, this);
}
return true;
}
return false;
}
@Override
protected boolean doForceSetElement(int element) throws ContradictionException {
if (getVariables()[element - this.offset].instantiateTo(BoolVar.kTRUE, this)) {
lb.add(element);
if (reactOnModification) {
delta.add(element, SetDelta.LB, this);
}
return true;
}
return false;
}
@Override
public void notify(IEventType event, int variableIdx) throws ContradictionException {
if (this.getVariables()[variableIdx].isInstantiatedTo(BoolVar.kTRUE)) {
lb.add(variableIdx + offset);
if (reactOnModification) {
delta.add(variableIdx + offset, SetDelta.LB, this);
}
notifyPropagators(SetEventType.ADD_TO_KER, this);
} else if (this.getVariables()[variableIdx].isInstantiatedTo(BoolVar.kFALSE)) {
ub.remove(variableIdx + offset);
if (reactOnModification) {
delta.add(variableIdx + offset, SetDelta.UB, this);
}
notifyPropagators(SetEventType.REMOVE_FROM_ENVELOPE, this);
}
}
@Override
public ISet getLB() {
return lb;
}
@Override
public ISet getUB() {
return ub;
}
@Override
public boolean instantiateTo(int[] value, ICause cause) throws ContradictionException {
boolean changed = !isInstantiated();
ISet s = SetFactory.makeConstantSet(Arrays.stream(value).map(i -> i - offset).toArray());
for (int i = 0; i < getNbObservedVariables(); i++) {
B var = getVariables()[i];
if (s.contains(i)) {
lb.add(i + offset);
var.instantiateTo(BoolVar.kTRUE, this);
} else {
ub.remove(i + offset);
var.instantiateTo(BoolVar.kFALSE, this);
}
}
return changed;
}
@Override
public boolean isInstantiated() {
for (B var : getVariables()) {
if (!var.isInstantiated()) {
return false;
}
}
return true;
}
@Override
public ISetDelta getDelta() {
return delta;
}
@Override
public void createDelta() {
if (!reactOnModification) {
reactOnModification = true;
delta = new SetDelta(model.getEnvironment());
}
}
@Override
public ISetDeltaMonitor monitorDelta(ICause propagator) {
createDelta();
return new SetDeltaMonitor(getDelta(), propagator);
}
}