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/*
* 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.constraints;
import org.chocosolver.memory.structure.IOperation;
import org.chocosolver.solver.ICause;
import org.chocosolver.solver.Identity;
import org.chocosolver.solver.Model;
import org.chocosolver.solver.Priority;
import org.chocosolver.solver.exception.ContradictionException;
import org.chocosolver.solver.exception.SolverException;
import org.chocosolver.solver.learn.ExplanationForSignedClause;
import org.chocosolver.solver.variables.BoolVar;
import org.chocosolver.solver.variables.IntVar;
import org.chocosolver.solver.variables.Variable;
import org.chocosolver.solver.variables.events.IEventType;
import org.chocosolver.solver.variables.events.IntEventType;
import org.chocosolver.solver.variables.events.PropagatorEventType;
import org.chocosolver.util.ESat;
import org.chocosolver.util.objects.IntCircularQueue;
import org.chocosolver.util.objects.queues.CircularQueue;
import org.chocosolver.util.objects.setDataStructures.iterable.IntIterableRangeSet;
import java.util.Arrays;
import java.util.function.Consumer;
import static java.lang.System.arraycopy;
import static java.util.Arrays.copyOf;
import static org.chocosolver.solver.constraints.PropagatorPriority.LINEAR;
import static org.chocosolver.solver.variables.events.IEventType.ALL_EVENTS;
import static org.chocosolver.solver.variables.events.PropagatorEventType.CUSTOM_PROPAGATION;
import static org.chocosolver.util.objects.setDataStructures.iterable.IntIterableSetUtils.unionOf;
/**
* A Propagator class defines methods to react on a Variable objects modifications.
* It is observed by Constraint objects and can notify them when a Variable event occurs.
*
* Propagator methods are assumed to be idempotent, ie :
* Let f be a propagator method, such that f : D -> D' include D, where D the union of variable domains involved in f.
* Then, f(D)=f(D').
*
*
* A Propagator declares a filtering algorithm to apply to the Variables objects
* in scope in order to reduce their Domain objects.
* That's why the propagate method should be adapted to the expected filtering algorithm.
* This method is called through Constraint observers when an event occurs on a scoped Variable
* object. propagate method can throw a ContradictionException
* when this Propagator object detects a contradiction, within its filtering algorithm, like domain wipe out,
* out of domain value instantiation or other incoherence.
*
* Furthermore, a Propagator object can be entailed : considering the current state of its Variable
* objects, the internal filtering algorithm becomes useless (for example: NEQ propagator and a couple of Variable
* objects with disjoint domains). In other words, whatever are the future events occurring on Variable objects,
* new calls to propagate method would be useless.
*
* this can be deactivated using the setPassivemethod.
* It automatically informs Constraint observers of this new "state".
*
* The developer of a propagator must respect some rules to create a efficient propagator:
*
- internal references to variables must be achieved referencing the this.vars after the call to super,
* this prevents from wrong references when a variable occurs more than once in the scope (See {@link org.chocosolver.solver.constraints.nary.count.PropCount_AC} for instance).
*
- //to complete
*
* @author Xavier Lorca
* @author Charles Prud'homme
* @author Jean-Guillaume Fages
* @version 0.01, june 2010
* @see org.chocosolver.solver.variables.Variable
* @see Constraint
* @since 0.01
* @param type of variables involved in this propagator
*/
public abstract class Propagator implements ICause, Identity, Comparable> {
/**
* Status of this propagator on creation.
*/
private static final short NEW = 0;
/**
* Status of this propagator when reified.
*/
private static final short REIFIED = 1;
/**
* Status of the propagator when activated (ie, after initial propagation).
*/
protected static final short ACTIVE = 2;
/**
* Status of the propagator when entailed.
*/
private static final short PASSIVE = 3;
/**
* Ignore propagation during execution.
*/
private boolean enabled = true;
/**
* For debugging purpose only, set to true to use default explanation schema, false to fail
*/
@SuppressWarnings("WeakerAccess")
public static boolean DEFAULT_EXPL = true;
/**
* Set to true to output the name of the constraint that use the default explanation schema
*/
@SuppressWarnings("WeakerAccess")
public static boolean OUTPUT_DEFAULT_EXPL = false;
/**
* Unique ID of this propagator.
*/
private final int ID;
/**
* Current status of this propagator.
* In: {@link #NEW}, {@link #REIFIED}, {@link #ACTIVE} and {@link #PASSIVE}.
*/
protected short state = NEW;
/**
* Backtrackable operations to maintain the status on backtrack.
*/
protected IOperation[] operations;
/**
* On propagator passivation, should this propagator be swapped from active to passive in its
* variables' propagators list.
*/
private final boolean swapOnPassivate;
/**
* Priority of this propagator.
* Mix between arity and compexity.
*/
protected final Priority priority;
/**
* Set to true to indidates that this propagator reacts to fine event.
* If set to false, the method {@link #propagate(int, int)} will never be called.
*/
protected final boolean reactToFineEvt;
/**
* Encapsuling constraint.
*/
protected Constraint constraint;
/**
* Reference to the model declaring this propagator.
*/
protected final Model model;
/**
* List of variables this propagators deal with.
* A variable can occur more than once, but it is considered then as n distinct variables.
*/
protected V[] vars;
/**
* Index of this propagator within each variable's propagators.
*/
private int[] vindices;
////////////////////////////////////////////////////////////////////////////////////////////////
// FOR PROPAGATION PURPOSE
////////////////////////////////////////////////////////////////////////////////////////////////
/**
* True if this is scheduled for propagation
*/
private boolean scheduled;
/**
* This set of events (modified variables) to propagate next time
*/
private IntCircularQueue eventsets;
/**
* This set of events' mask to propagate next time
*/
private int[] eventmasks;
/**
* Position of this in the propgation engine
*/
private int position = -1;
/**
* A bi-int-consumer
*/
private interface IntIntConsumer{
void accept(int a, int b);
}
/**
* Default action to do on fine event : nothing
*/
private IntIntConsumer fineevt = (i, m) -> {};
/**
* Denotes the reifying variable when this propagator is reified, null otherwise.
*/
private BoolVar reifVar;
/**
* Creates a new propagator to filter the domains of vars.
*
*
* To limit memory consumption, the array of variables is referenced directly (no clone).
* This is the responsibility of the propagator's developer to take care of that point.
*
* @param vars variables of the propagator. Their modification will trigger
* filtering
* @param priority priority of this propagator (lowest priority propagators are called
* first)
* @param reactToFineEvt indicates whether or not this propagator must be informed of every
* variable modification, i.e. if it should be incremental or not
* @param swapOnPassivate indicates if, on propagator passivation, the propagator should be
* ignored in its variables' propagators list.
*/
protected Propagator(V[] vars, Priority priority, boolean reactToFineEvt, boolean swapOnPassivate) {
assert vars != null && vars.length > 0 && vars[0] != null : "wrong variable set in propagator constructor";
this.model = vars[0].getModel();
this.reactToFineEvt = reactToFineEvt;
this.priority = priority;
// To avoid too much memory consumption, the array of variables is referenced directly, no clone anymore.
// This is the responsibility of the propagator's developer to take care of that point.
if (model.getSettings().cloneVariableArrayInPropagator()) {
this.vars = vars.clone();
} else {
this.vars = vars;
}
this.vindices = new int[vars.length];
Arrays.fill(vindices, -1);
ID = model.nextId();
this.swapOnPassivate = model.getSettings().swapOnPassivate() & swapOnPassivate;
operations = new IOperation[3];
operations[0] = () -> state = NEW;
operations[1] = () -> state = REIFIED;
operations[2] = () -> state = ACTIVE;
// for propagation purpose
eventmasks = new int[vars.length];
if (reactToFineEvent()) {
eventsets = new IntCircularQueue(vars.length);
eventmasks = new int[vars.length];
fineevt = (i, m) -> {
if (eventmasks[i] == 0) {
eventsets.addLast(i);
}
eventmasks[i] |= m;
};
}
}
/**
* Creates a new propagator to filter the domains of vars.
*
*
* To limit memory consumption, the array of variables is referenced directly (no clone).
* This is the responsibility of the propagator's developer to take care of that point.
*
* @param vars variables of the propagator. Their modification will trigger filtering
* @param priority priority of this propagator (lowest priority propagators are called
* first)
* @param reactToFineEvt indicates whether or not this propagator must be informed of every
* variable modification, i.e. if it should be incremental or not
*/
protected Propagator(V[] vars, Priority priority, boolean reactToFineEvt) {
this(vars, priority, reactToFineEvt, true);
}
/**
* Creates a non-incremental propagator which does not react to fine events but simply calls a
* coarse propagation any time a variable in vars has changed.
* This propagator has a regular (linear) priority.
*
* @param vars variables of the propagator. Their modification will trigger filtering
*/
@SafeVarargs
protected Propagator(V... vars) {
this(vars, LINEAR, false);
}
//***********************************************************************************
// METHODS
//***********************************************************************************
/**
* Enlarges the variable scope of this propagator
* Should not be called by the user.
*
* @param nvars variables to be added to this propagator
*/
@SafeVarargs
protected final void addVariable(V... nvars) {
assert !swapOnPassivate:"Cannot add variable to a propagator that allows being swapped on passivate";
V[] tmp = vars;
vars = copyOf(vars, vars.length + nvars.length);
arraycopy(nvars, 0, vars, tmp.length, nvars.length);
int[] itmp = this.vindices;
vindices = new int[vars.length];
arraycopy(itmp, 0, vindices, 0, itmp.length);
for (int v = tmp.length; v < vars.length; v++) {
vars[v].link(this, v);
}
if(reactToFineEvt) {
itmp = this.eventmasks;
eventmasks = new int[vars.length];
arraycopy(itmp, 0, eventmasks, 0, itmp.length);
}
if (model.getSolver().getEngine().isInitialized()) {
model.getSolver().getEngine().updateInvolvedVariables(this);
}
}
/**
* Creates links between this propagator and its variables.
* The propagator will then be referenced in each of its variables.
*/
public final void linkVariables() {
for (int v = 0; v < vars.length; v++) {
if (!vars[v].isAConstant()) {
vars[v].link(this, v);
}
}
}
/**
* Destroy links between this propagator and its variables.
*/
public final void unlinkVariables() {
for (int v = 0; v < vars.length; v++) {
if (!vars[v].isAConstant()) {
vars[v].unlink(this, v);
vindices[v] = -1;
}
}
}
/**
* Informs this propagator the (unique) constraint it filters.
* The constraint reference will be overwritten in case of reification.
* Should not be called by the user.
*
* @param c the constraint containing this propagator
* @throws SolverException if the propagator is declared in more than one constraint
*/
void defineIn(Constraint c) throws SolverException {
if ((constraint != null && constraint.getStatus() != Constraint.Status.FREE)
|| (c.getStatus() != Constraint.Status.FREE)) {
throw new SolverException("This propagator is already defined in a constraint. " +
"This happens when a constraint is reified and posted.");
}
this.constraint = c;
}
/**
* Returns the specific mask indicating the variable events on which this Propagator object can react.
* A mask is a bitwise OR operations over {@link IEventType} this can react on.
*
* For example, consider a propagator that can deduce filtering based on the lower bound of the integer variable X.
* Then, for this variable, the mask should be equal to :
*
* int mask = IntEventType.INCLOW.getMask() | IntEventType.INSTANTIATE.getMask();
*
* or, in a more convenient way:
*
* int mask = IntEvtType.combine(IntEventType.INCLOW,IntEventType.INSTANTIATE);
*
*
* That indicates the following behavior:
*
* - if X is instantiated, this propagator will be executed,
* - if the lower bound of X is modified, this propagator will be executed,
* - if the lower bound of X is removed, the event is promoted from REMOVE to INCLOW and this propagator will NOT be executed,
* - otherwise, this propagator will NOT be executed
*
*
* Some combinations are valid.
* For example, a propagator which reacts on REMOVE and INSTANTIATE should also declare INCLOW and DECUPP as conditions.
* Indeed INCLOW (resp. DECUPP), for efficiency purpose, removing the lower bound (resp. upper bound) of an integer variable
* will automatically be promoted into INCLOW (resp. DECUPP).
* So, ignoring INCLOW and/or DECUPP in that case may result in a lack of filtering.
*
* The same goes with events of other variable types, but most of the time, there are only few combinations.
*
* Reacts to any kind of event by default.
*
* Alternatively, this method can return {@link IntEventType#VOID} which states
* that this propagator should not be aware of modifications applied to the variable in position vIdx.
*
* @param vIdx index of the variable within the propagator
* @return an int composed of REMOVE and/or INSTANTIATE
* and/or DECUPP and/or INCLOW
*/
public int getPropagationConditions(int vIdx) {
return ALL_EVENTS;
}
/**
* Call the main filtering algorithm to apply to the Domain of the Variable objects.
* It considers the current state of this objects to remove some values from domains and/or instantiate some variables.
* Calling this method is done from 2 (and only 2) steps:
*
- at the initial propagation step,
*
- when involved in a reified constraint.
*
* It should initialized the internal data structure and apply filtering algorithm from scratch.
*
* @param evtmask type of propagation event this must consider.
* @throws org.chocosolver.solver.exception.ContradictionException when a contradiction occurs, like domain wipe out or other incoherencies.
*/
public abstract void propagate(int evtmask) throws ContradictionException;
/**
* Incremental filtering algorithm defined within the Propagator, called whenever the variable
* of index idxVarInProp has changed. This method calls a CUSTOM_PROPAGATION (coarse-grained) by default.
*
* This method should be overridden if the argument reactToFineEvt is set to true in the constructor.
* Otherwise, it executes propagate(PropagatorEventType.CUSTOM_PROPAGATION.getStrengthenedMask());
*
* @param idxVarInProp index of the variable var in this
* @param mask type of event
* @throws org.chocosolver.solver.exception.ContradictionException if a contradiction occurs
*/
public void propagate(int idxVarInProp, int mask) throws ContradictionException {
if (reactToFineEvt) {
throw new SolverException(this + " has been declared to ignore which variable is modified.\n" +
"To change the configuration, consider:\n" +
"- to set 'reactToFineEvt' to false or,\n" +
"- to override the following method:\n" +
"\t'public void propagate(int idxVarInProp, int mask) throws ContradictionException'." +
"The latter enables incrementality but also to delay calls to complex filtering algorithm (see the method 'forcePropagate(EventType evt)'.");
}
propagate(CUSTOM_PROPAGATION.getMask());
}
/**
* Schedules a coarse propagation to filter all variables at once.
*
* Add the coarse event recorder into the engine
*
* @param evt event type
* @throws ContradictionException if the propagation encounters inconsistency.
*/
public final void forcePropagate(PropagatorEventType evt) throws ContradictionException {
model.getSolver().getEngine().delayedPropagation(this, evt);
}
/**
* informs that this propagator is now active. Should not be called by the user.
* @throws SolverException if the propagator cannot be activated due to its current state
*/
public void setActive() throws SolverException {
if (isStateLess()) {
state = ACTIVE;
model.getEnvironment().save(operations[NEW]);
} else {
throw new SolverException("Try to activate a propagator already active, passive or reified.\n" +
this + " of " + this.getConstraint());
}
}
protected void setActive0() {
state = ACTIVE;
}
/**
* informs that this reified propagator must hold. Should not be called by the user.
* @throws SolverException if the propagator cannot be activated due to its current state
*/
public void setReifiedTrue() throws SolverException {
if (isReifiedAndSilent()) {
state = ACTIVE;
model.getEnvironment().save(operations[REIFIED]);
} else {
throw new SolverException("Reification process tries to force activation of a propagator already active or passive.\n" +
this + " of " + this.getConstraint());
}
}
/**
* informs that this reified propagator may not hold. Should not be called by the user.
* @param boolVar the reifying variable
* @throws SolverException if the propagator cannot be reified due to its current state
*/
public void setReifiedSilent(BoolVar boolVar) throws SolverException {
if (isStateLess() || isReifiedAndSilent()) {
state = REIFIED;
this.reifVar = boolVar;
} else {
throw new SolverException("Reification process try to reify a propagator already active or posted.\n" +
this + " of " + this.getConstraint());
}
}
/**
* informs that this propagator is now passive : it holds but no further filtering can occur,
* so it is useless to propagate it. Should not be called by the user.
* @throws SolverException if the propagator cannot be set passive due to its current state
*/
public void setPassive() throws SolverException {
// Note: calling isCompletelyInstantiated() to avoid next steps may lead to error when
// dealing with reification and dynamic addition.
if (isActive()) {
state = PASSIVE;
model.getEnvironment().save(operations[ACTIVE]);
//TODO: update var mask back
model.getSolver().getEngine().desactivatePropagator(this);
if (swapOnPassivate) {
for (int i = 0; i < vars.length; i++) {
if (!vars[i].isInstantiated()) {
vars[i].swapOnPassivate(this, i);
}
}
}
} else {
throw new SolverException("Try to passivate a propagator already passive or reified.\n" +
this + " of " + this.getConstraint());
}
}
/**
* Call this method when either the propagator has to be awake on backtrack.
* This is helpful when:
*
* - the scope of this propagator has changed on failures or solutions (eg. learning clauses)
* - this propagator's internal structure has changed (eg. this acts as a cut)
*
*/
protected void forcePropagationOnBacktrack() {
if (isPassive()) { // force activation on backtrack, because something can have changed on our back
if (this instanceof UpdatablePropagator) {
state = ACTIVE;
} else {
throw new SolverException("Try to force propagation on an inactive propagator.\n" +
this + " of " + this.getConstraint());
}
}
model.getSolver().getEngine().propagateOnBacktrack(this);
}
/**
* Check wether this is entailed according to the current state of its internal structure.
* At least, should check the satisfaction of this (when all is instantiated).
*
* @return ESat.TRUE if entailed, ESat.FALSE if not entailed, ESat.UNDEFINED if unknown
*/
public abstract ESat isEntailed();
/**
* @return true iff all this propagator's variables are instantiated
*/
public boolean isCompletelyInstantiated() {
for (int i = 0; i < vars.length; i++) {
if (!vars[i].isInstantiated()) {
return false;
}
}
return true;
}
/**
* @return the number of uninstantiated variables
*/
public int arity() {
int arity = 0;
for (int i = 0; i < vars.length; i++) {
arity += vars[i].isInstantiated() ? 0 : 1;
}
return arity;
}
/**
* Return the dynamic priority of this propagator.
* It excludes from the arity variables instantiated.
* But may be time consuming.
* @return a more accurate priority excluding instantiated variables.
*/
@SuppressWarnings("unused")
public int dynPriority() {
int arity = 0;
for (int i = 0; i < vars.length && arity <= 3; i++) {
arity += vars[i].isInstantiated() ? 0 : 1;
}
if (arity > 3) {
return priority.getValue();
} else return arity;
}
/**
* Throws a contradiction exception
*
* @throws org.chocosolver.solver.exception.ContradictionException expected behavior
*/
public void fails() throws ContradictionException {
model.getSolver().throwsException(this, null, null);
}
/**
* Throws a contradiction exception with a specific message
*
* @param message the message associated with the failure
* @throws org.chocosolver.solver.exception.ContradictionException expected behavior
*/
public void fails(String message) throws ContradictionException {
model.getSolver().throwsException(this, null, message);
}
@Override
public int compareTo(Propagator o) {
return this.ID - o.ID;
}
/**
* @return the boolean variable that reifies this propagator, null otherwise.
*/
public BoolVar reifiedWith() {
return reifVar;
}
/**
* @return true if this is reified.
* Call {@link #reifiedWith()} to get the reifying variable.
*/
public boolean isReified(){
return reifVar != null;
}
//***********************************************************************************
// ACCESSORS
//***********************************************************************************
@Override
public int getId() {
return ID;
}
/**
* @return the model this propagator is defined in
*/
public Model getModel() {
return model;
}
@Override
public int hashCode() {
return ID;
}
@Override
public boolean equals(Object o) {
return o instanceof Propagator && ((Propagator) o).ID == ID;
}
/**
* Returns the element at the specified position in this internal list of V objects.
*
* @param i index of the element
* @return a V object
*/
public final V getVar(int i) {
return vars[i];
}
/**
* @return the variable set this propagator holds on.
* Note that variable multiple occurrence may have lead to variable duplications
* (i.e. the creation of new variable)
*/
public final V[] getVars() {
return vars;
}
/**
* @return the index of the propagator within its variables
*/
@SuppressWarnings("unused")
public int[] getVIndices() {
return vindices;
}
/**
* @return the index of the propagator within its idx^th variable
*/
@SuppressWarnings("unused")
public int getVIndice(int idx) {
return vindices[idx];
}
/**
* Changes the index of a variable in this propagator.
* This method should not be called by the user.
*
* @param idx old index
* @param val new index
*/
@SuppressWarnings("unused")
public void setVIndices(int idx, int val) {
vindices[idx] = val;
}
/**
* @return the number of variables involved in this.
*/
public final int getNbVars() {
return vars.length;
}
/**
* @return the constraint including this propagator
*/
public final Constraint getConstraint() {
return constraint;
}
/**
* @return the priority of this propagator (may influence the order in which propagators are called)
*/
public final Priority getPriority() {
return priority;
}
/**
* @return true iff this propagator is stateless: its initial propagation has not been performed yet
*/
public boolean isStateLess() {
return state == NEW;
}
/**
* @return true iff this propagator is reified and it is not established yet whether it should hold or not
*/
public boolean isReifiedAndSilent() {
return state == REIFIED;
}
/**
* The propagator is active if the state is ACTIVE and the constraint related to it is enabled.
* The constraint is disabled to allow faster execution of algorithms like {@link org.chocosolver.solver.QuickXPlain}.
*
* @return true iff this propagator is active (it should filter)
*/
public boolean isActive() {
return state == ACTIVE && enabled;
}
/**
* @return true iff this propagator is passive. This happens when it is entailed : the propagator still hold
* but no more filtering can occur
*/
@SuppressWarnings("WeakerAccess")
public boolean isPassive() {
return state == PASSIVE;
}
/**
* @return true iff the propagator reacts to fine event, that is,
* it needs to know which variable has been modified and the modification that happened.
*/
public final boolean reactToFineEvent() {
return reactToFineEvt;
}
@Override
public String toString() {
StringBuilder st = new StringBuilder();
st.append(getClass().getSimpleName()).append("(");
int i = 0;
if (vars.length >= 3) st.append(vars[i++].getName()).append(", ");
if (vars.length >= 2) st.append(vars[i++].getName()).append(", ");
if (vars.length >= 1) st.append(vars[i++].getName());
if (i < vars.length) {
if (vars.length > 4) {
st.append(", ...");
}
st.append(", ").append(vars[vars.length - 1].getName());
}
st.append(')');
return st.toString();
}
/**
* @implSpec
* Based on the scope of this propagator, domains of variables are extracted as they
* were just before propagation that leads to node p.
*
* Consider that v_1 has been modified by propagation of this.
* Before the propagation, the domains were like:
*
* (v1 ∈ D1 ∧ v2 ∈ D2 ∧ .... ∧ vn ∈ D_n)
*
* Then this propagates v1 ∈ D1', then:
*
* (v1 ∈ D1 ∧ v2 ∈ D2 ∧ .... ∧ vn ∈ D_n) → v1 ∈ D1'
*
* Converting to DNF:
*
* (v1 ∈ (U \ D1) ∪ D'1 ∨ v2 ∈ (U \ D2) ∨ .... ∨ vn ∈ (U \ Dn))
*
*
*/
@Override
public void explain(int p, ExplanationForSignedClause explanation) {
if (DEFAULT_EXPL) {
if(OUTPUT_DEFAULT_EXPL)model.getSolver().log().bold().printf("-- default explain for %s \n",this.getClass().getSimpleName());
defaultExplain(this, p, explanation);
} else {
ICause.super.explain(p, explanation);
}
}
public static void defaultExplain(Propagator prop, int p, ExplanationForSignedClause explanation) {
IntVar pivot = p > -1 ? explanation.readVar(p) : null;
IntIterableRangeSet dom;
IntVar var;
boolean found = false;
for (int i = 0; i < prop.vars.length; i++) {
var = (IntVar) prop.vars[i];
if (var == pivot) {
if (!found) {
dom = explanation.complement(var);
// when a variable appears more than once AND is pivot : should be treated only once
unionOf(dom, explanation.readDom(p));
found = true;
var.intersectLit(dom, explanation);
}
}else{
var.unionLit(explanation.complement(var), explanation);
}
}
assert found || p == -1 : pivot + " not declared in scope of " + prop;
}
@Override
public void forEachIntVar(Consumer action) {
for (int i = 0; i < vars.length; i++) {
action.accept((IntVar) vars[i]);
}
}
////////////////////////////////////////////////////////////////////////////////////////////////
// FOR PROPAGATION PURPOSE
////////////////////////////////////////////////////////////////////////////////////////////////
/**
* @return the position of this in the propagation engine
*/
public int getPosition(){
return position;
}
/**
* Set the position of this in the propagation engine or -1 if removed.
* @param p position of this in the propagation engine or -1 if removed.
*/
public void setPosition(int p){
this.position = p;
}
/**
* Set this as unscheduled
*/
public final void unschedule(){
scheduled = false;
}
private void schedule(){
scheduled = true;
}
/**
* @return true if scheduled for propagation
*/
public final boolean isScheduled() {
return scheduled;
}
/**
* Apply scheduling instruction
* @param queues array of queues in which this can be scheduled
* @return propagator priority
*/
public int doSchedule(CircularQueue>[] queues){
int prio = priority.getValue();
if(!scheduled) {
queues[prio].addLast(this);
schedule();
}
return prio;
}
public void doScheduleEvent(int pindice, int mask){
fineevt.accept(pindice, mask);
}
/**
* Apply fine event propagation of this.
* It iterates over pending modified variables and run propagation on each of them.
* @throws ContradictionException if a contradiction occurred.
*/
public void doFinePropagation() throws ContradictionException {
while (eventsets.size() > 0) {
int v = eventsets.pollFirst();
assert isActive() : "propagator is not active:" + this.getClass();
// clear event
int mask = eventmasks[v];
eventmasks[v] = 0;
// run propagation on the specific event
propagate(v, mask);
}
}
/**
* Flush pending events
*/
public void doFlush(){
if (reactToFineEvent()) {
while (eventsets.size() > 0) {
int v = eventsets.pollLast();
eventmasks[v] = 0;
}
}
unschedule();
}
/**
* Disable a propagator from being propagated during search and from feasibility
* check ({@link org.chocosolver.solver.Solver#isSatisfied()}). A propagator
* shouldn't swap between enabled/disabled during solver execution (branching,
* filtering, etc...) because there is not control of the side effects it can
* cause (e.g.: when at node n, if a propagator becomes disabled, it doesn't
* undo filtering it has done at n-1).
* See {@link Constraint#setEnabled(boolean)}
*
* @param enabled is this propagator enabled?
*/
public void setEnabled(boolean enabled) {
this.enabled = enabled;
}
}