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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.variables.impl;
import org.chocosolver.memory.IEnvironment;
import org.chocosolver.memory.IStateInt;
import org.chocosolver.solver.Cause;
import org.chocosolver.solver.ICause;
import org.chocosolver.solver.Model;
import org.chocosolver.solver.constraints.Propagator;
import org.chocosolver.solver.exception.ContradictionException;
import org.chocosolver.solver.propagation.PropagationEngine;
import org.chocosolver.solver.variables.*;
import org.chocosolver.solver.variables.events.IEventType;
import org.chocosolver.solver.variables.view.IView;
import org.chocosolver.util.iterators.EvtScheduler;
import java.util.Arrays;
import java.util.Objects;
import java.util.Spliterator;
import java.util.function.Consumer;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
/**
* Class used to factorise code The subclass must implement Variable interface
*
* @author Jean-Guillaume Fages
* @author Charles Prud'homme
* @since 30 june 2011
*/
public abstract class AbstractVariable implements Variable {
/**
* Message associated with last value removals exception.
*/
static final String MSG_REMOVE = "remove last value";
/**
* Message associated with domain wipe out exception.
*/
protected static final String MSG_EMPTY = "empty domain";
/**
* Message associated with double instantiation exception.
*/
protected static final String MSG_INST = "the variable is already instantiated to another value";
/**
* Default exception message.
*/
static final String MSG_UNKNOWN = "unknown value";
/**
* Message associated with wrong upper bound exception.
*/
static final String MSG_UPP = "the new upper bound is lesser than the current lower bound";
/**
* Message associated with wrong lower bound exception.
*/
static final String MSG_LOW = "the new lower bound is greater than the current upper bound";
/**
* Message associated with wrong bounds exception.
*/
static final String MSG_BOUND = "new bounds are incorrect";
/**
* Unique ID of this variable.
*/
private final int ID;
/**
* Reference to the model containing this variable (unique).
*/
protected final Model model;
/**
* Name of the variable.
*/
protected final String name;
/**
* List of propagators, by event type
*/
final BipartiteList[] propagators;
/**
* Nb dependencies
*/
private int nbPropagators;
/**
* List of views based on this variable.
*/
private IView[] views;
/**
* Indices of this variable in subscribed views
*/
private int[] idxInViews;
/**
* Index of the last not null view in views.
*/
private int vIdx;
/**
* List of monitors observing this variable.
*/
@SuppressWarnings("rawtypes")
protected IVariableMonitor[] monitors;
/**
* Index of the last not null monitor in monitors.
*/
protected int mIdx;
/**
* The event scheduler of this variable, for efficient scheduling purpose. It stores propagators
* wrt the propagation conditions.
*/
private final EvtScheduler scheduler;
/**
* World index of last instantiation event.
*/
private int instWI;
////////////////////////////////////////////////////////////////////////////////////////////////
// FOR PROPAGATION PURPOSE
////////////////////////////////////////////////////////////////////////////////////////////////
/**
* possibly aggregated event's mask
*/
private int mask;
/**
* possibly aggregated event's cause
*/
private ICause cause;
/**
* True if related propagators are scheduled for propagation
*/
public boolean scheduled;
//////////////////////////////////////////////////////////////////////////////////////
/**
* Create the shared data of any type of variable.
*
* @param name name of the variable
* @param model model which declares this variable
*/
protected AbstractVariable(String name, Model model) {
this.name = name;
this.model = model;
this.views = new IView[2];
this.idxInViews = new int[2];
this.monitors = new IVariableMonitor[2];
this.scheduler = createScheduler();
int dsize = this.scheduler.select(0);
this.propagators = new BipartiteList[dsize + 1];
for (int i = 0; i < dsize + 1; i++) {
this.propagators[i] = new BipartiteList(model.getEnvironment());
}
this.nbPropagators = 0;
this.ID = this.model.nextId();
this.model.associates(this);
this.instWI = 0; // set to 0 to capture constant automatically
this.scheduled = false;
}
protected abstract EvtScheduler createScheduler();
@Override
public boolean isScheduled() {
return scheduled;
}
@Override
public void schedule() {
this.scheduled = true;
}
@Override
public void schedulePropagators(PropagationEngine engine) {
if (mask > 0) {
EvtScheduler si = this.getEvtScheduler();
si.init(mask);
while (si.hasNext()) {
int i = si.next();
int j = si.next();
for (; i < j; i++) {
propagators[i].schedule(cause, engine, mask);
}
}
}
this.clearEvents();
}
@Override
public void unschedule() {
this.scheduled = false;
}
@Override
public final int getId() {
return ID;
}
@Override
public final void link(Propagator propagator, int idxInProp) {
int i = scheduler.select(propagator.getPropagationConditions(idxInProp));
nbPropagators++;
propagator.setVIndices(idxInProp, propagators[i].add(propagator, idxInProp));
}
@Override
public final void unlink(Propagator propagator, int idxInProp) {
int i = scheduler.select(propagator.getPropagationConditions(idxInProp));
nbPropagators--;
propagators[i].remove(propagator, idxInProp, this);
}
@Override
public void swapOnPassivate(Propagator propagator, int idxInProp) {
int i = scheduler.select(propagator.getPropagationConditions(idxInProp));
propagators[i].swap(propagator, idxInProp, this);
}
@Override
@Deprecated
public int swapOnActivate(Propagator propagator, int idxInProp) {
throw new UnsupportedOperationException("Cannot swap on activation");
}
@Override
public final Propagator[] getPropagators() {
throw new UnsupportedOperationException("The method is deprecated");
}
@Override
public final Propagator getPropagator(int idx) {
throw new UnsupportedOperationException("The method is deprecated");
}
@Override
public Stream> streamPropagators() {
Spliterator> it = new Spliterator>() {
int c = 0;
int i = propagators[c].first;
@Override
public boolean tryAdvance(Consumer> action) {
do {
if (i < propagators[c].last) {
action.accept(propagators[c].propagators[i++]);
return true;
} else {
c++;
if (c < propagators.length) {
i = propagators[c].first;
} else {
return false;
}
}
} while (true);
}
@Override
public Spliterator> trySplit() {
return null;
}
@Override
public long estimateSize() {
return nbPropagators;
}
@Override
public int characteristics() {
return Spliterator.ORDERED | Spliterator.DISTINCT | Spliterator.NONNULL | Spliterator.CONCURRENT;
}
};
return StreamSupport.stream(it, false);
}
@Override
public final int getNbProps() {
return nbPropagators;
}
@Override
public final int[] getPIndices() {
throw new UnsupportedOperationException("The method is deprecated");
}
@Override
public final void setPIndice(int pos, int val) {
//pindices[pos] = val;
throw new UnsupportedOperationException("setPIndice to be implemented");
}
@Override
@Deprecated
public final int getDindex(int i) {
throw new UnsupportedOperationException("The method is deprecated");
}
@Override
public final int getIndexInPropagator(int pidx) {
//return pindices[pidx];
throw new UnsupportedOperationException("setPIndice to be implemented");
}
@Override
public int instantiationWorldIndex() {
return this.isInstantiated() ? this.instWI : Integer.MAX_VALUE;
}
@Override
public void recordWorldIndex() {
this.instWI = model.getEnvironment().getWorldIndex();
}
@Override
public final String getName() {
return this.name;
}
////////////////////////////////////////////////////////////////
///// methodes de l'interface Variable /////
////////////////////////////////////////////////////////////////
@Override
public void notifyPropagators(IEventType event, ICause cause) throws ContradictionException {
assert cause != null;
if (this.isInstantiated()) {
recordWorldIndex();
}
model.getSolver().getEngine().onVariableUpdate(this, event, cause);
notifyMonitors(event);
notifyViews(event, cause);
}
public void notifyMonitors(IEventType event) throws ContradictionException {
for (int i = mIdx - 1; i >= 0; i--) {
//noinspection unchecked
monitors[i].onUpdate(this, event);
}
}
@Override
public void notifyViews(IEventType event, ICause cause) throws ContradictionException {
assert cause != null;
if (cause == Cause.Null) {
for (int i = vIdx - 1; i >= 0; i--) {
views[i].notify(event, idxInViews[i]);
}
} else {
for (int i = vIdx - 1; i >= 0; i--) {
if (views[i] != cause) { // reference is enough
views[i].notify(event, idxInViews[i]);
}
}
}
}
@Override
public void addMonitor(IVariableMonitor monitor) {
// 1. check the non redundancy of a monitor if expected.
if (model.getSettings().checkDeclaredMonitors()) {
for (int i = 0; i < mIdx; i++) {
if (monitors[i] == monitor) return;
}
}
// 2. then add the monitor
if (mIdx == monitors.length) {
IVariableMonitor[] tmp = monitors;
monitors = new IVariableMonitor[tmp.length * 3 / 2 + 1];
System.arraycopy(tmp, 0, monitors, 0, mIdx);
}
monitors[mIdx++] = monitor;
}
@Override
public void removeMonitor(IVariableMonitor monitor) {
int i = mIdx - 1;
for (; i >= 0; i--) {
if (monitors[i] == monitor) break;
}
if (i < mIdx - 1) {
System.arraycopy(monitors, i + 1, monitors, i, mIdx - (i + 1));
}
monitors[--mIdx] = null;
}
@Override
public void subscribeView(IView view, int idx) {
if (vIdx == views.length) {
IView[] tmp = views;
int[] tmpIdx = idxInViews;
views = new IView[tmp.length * 3 / 2 + 1];
idxInViews = new int[tmp.length * 3 / 2 + 1];
System.arraycopy(tmp, 0, views, 0, vIdx);
System.arraycopy(tmpIdx, 0, idxInViews, 0, vIdx);
}
views[vIdx] = view;
idxInViews[vIdx] = idx;
vIdx++;
}
@Override
public final void contradiction(ICause cause, String message) throws ContradictionException {
assert cause != null;
model.getSolver().throwsException(cause, this, message);
}
public final Model getModel() {
return model;
}
@Override
public int getNbViews() {
return vIdx;
}
@Override
public IView getView(int idx) {
return views[idx];
}
@Override
public int compareTo(Variable o) {
return this.getId() - o.getId();
}
@Override
public String toString() {
return getName();
}
/**
* @return true if this variable has a domain included in [0,1].
*/
public final boolean isBool() {
return (getTypeAndKind() & KIND) == BOOL;
}
/**
* @return true if this variable has a singleton domain (different from instantiated)
*/
public final boolean isAConstant() {
return (getTypeAndKind() & TYPE) == CSTE;
}
/**
* @return the event scheduler
*/
public final EvtScheduler getEvtScheduler() {
return scheduler;
}
@Override
public IntVar asIntVar() {
return (IntVar) this;
}
@Override
public BoolVar asBoolVar() {
return (BoolVar) this;
}
@Override
public RealVar asRealVar() {
return (RealVar) this;
}
@Override
public SetVar asSetVar() {
return (SetVar) this;
}
@Override
public void storeEvents(int m, ICause cause) {
assert cause != null : "an event's cause is not supposed to be null";
if (this.cause == null) {
this.cause = cause;
} else if (this.cause != cause) {
this.cause = Cause.Null;
}
mask |= m;
}
@Override
public void clearEvents() {
this.cause = null;
mask = 0;
this.unschedule();
}
@Override
public int getMask() {
return mask;
}
@Override
public ICause getCause() {
return cause;
}
static class BipartiteList {
/**
* The current capacity
*/
private int capacity;
/**
* The position of the first element (inclusive)
*/
int first;
/**
* The position of the last element (exclusive)
*/
int last;
/**
* The number of passive propagators, starting from first
*/
final IStateInt splitter;
/**
* List of propagators
*/
Propagator[] propagators;
/**
* Store the index of each propagator.
*/
int[] pindices;
public BipartiteList(IEnvironment environment) {
this.splitter = environment.makeInt(0);
this.first = this.last = 0;
this.capacity = 10;
this.propagators = new Propagator[capacity];
this.pindices = new int[capacity];
}
/**
* Add a propagator p at the end of {@link #propagators}
* and set at the same position in {@link #pindices} the position
* of the variable in p.
*
* @param propagator the propagator to add
* @param idxInVar position of the variable in the propagator
* @return the number of propagators stored
*/
public int add(Propagator propagator, int idxInVar) {
if (first > 0 && splitter.get() == 0) {
shiftTail();
}
if (last == capacity - 1) {
capacity = capacity + (capacity >> 1);
propagators = Arrays.copyOf(propagators, capacity);
pindices = Arrays.copyOf(pindices, capacity);
}
propagators[last] = propagator;
pindices[last++] = idxInVar;
return last - 1;
}
/**
* Remove the propagator p from {@link #propagators}.
*
* @param propagator
* @param idxInProp
* @param var
*/
public void remove(Propagator propagator, int idxInProp, final AbstractVariable var) {
int p = propagator.getVIndice(idxInProp);
assert p > -1;
assert propagators[p] == propagator : "Try to unlink from " + var.getName() + ":\n" + propagator + "but found:\n" + propagators[p];
assert propagators[p].getVar(idxInProp) == var;
// Dynamic addition of a propagator may be not considered yet, so the assertion is not correct
if (p < splitter.get()) {
// swap the propagator to remove with the first one
propagator.setVIndices(idxInProp, -1);
propagators[p] = propagators[first];
pindices[p] = pindices[first];
propagators[p].setVIndices(pindices[p], p);
propagators[first] = null;
pindices[first] = 0;
first++;
} else {
// swap the propagator to remove with the last one
last--;
if (p < last) {
propagators[p] = propagators[last];
pindices[p] = pindices[last];
propagators[p].setVIndices(pindices[p], p);
}
propagators[last] = null;
pindices[last] = 0;
propagator.setVIndices(idxInProp, -1);
}
}
public void swap(Propagator propagator, int idxInProp, final AbstractVariable var) {
int p = propagator.getVIndice(idxInProp);
assert p != -1;
assert propagators[p] == propagator : "Try to swap from " + var.getName() + ":\n" + propagator + "but found: " + propagators[p];
assert propagators[p].getVar(idxInProp) == var;
int pos = splitter.add(1) - 1;
if (first > 0) {
if (pos == 0) {
shiftTail();
//then recompute the position of this
p = propagator.getVIndice(idxInProp);
} else {
// s = Math.min(s, first);
throw new UnsupportedOperationException();
}
}
if (pos < p) {
propagators[p] = propagators[pos];
propagators[pos] = propagator;
int pi = pindices[p];
pindices[p] = pindices[pos];
pindices[pos] = pi;
propagators[p].setVIndices(pindices[p], p);
propagators[pos].setVIndices(pindices[pos], pos);
assert propagators[pos] == propagator;
}
}
public void schedule(ICause cause, PropagationEngine engine, int mask) {
int s = splitter.get();
if (first > 0) {
if (s == 0) {
shiftTail();
} else {
throw new UnsupportedOperationException();
}
}
for (int p = s; p < last; p++) {
Propagator prop = propagators[p];
if (prop.isActive() && cause != prop) {
engine.schedule(prop, pindices[p], mask);
}
}
}
private void shiftTail() {
for (int i = 0; i < last - first; i++) {
propagators[i] = propagators[i + first];
pindices[i] = pindices[i + first];
propagators[i].setVIndices(pindices[i], i);
}
for (int i = last - first; i < last; i++) {
propagators[i] = null;
pindices[i] = 0;
}
last -= first;
first = 0;
}
Stream> stream() {
int s = splitter.get();
if (first > 0) {
if (s == 0) {
shiftTail();
}
}
Spliterator> it = new Spliterator>() {
int i = s;
@Override
public boolean tryAdvance(Consumer> action) {
if (i < last) {
action.accept(propagators[i++]);
return true;
} else {
return false;
}
}
@Override
public Spliterator> trySplit() {
return null;
}
@Override
public long estimateSize() {
return last - first;
}
@Override
public int characteristics() {
return Spliterator.ORDERED | Spliterator.DISTINCT | Spliterator.NONNULL | Spliterator.CONCURRENT;
}
};
return StreamSupport.stream(it, false);
}
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (!(o instanceof AbstractVariable)) return false;
AbstractVariable that = (AbstractVariable) o;
return ID == that.ID;
}
@Override
public int hashCode() {
return ID;
}
}