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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.solver.variables.GraphVar;
import org.chocosolver.solver.variables.delta.GraphDelta;
import org.chocosolver.solver.ICause;
import org.chocosolver.solver.Model;
import org.chocosolver.solver.exception.ContradictionException;
import org.chocosolver.solver.variables.delta.IGraphDeltaMonitor;
import org.chocosolver.solver.variables.delta.monitor.GraphDeltaMonitor;
import org.chocosolver.solver.variables.events.GraphEventType;
import org.chocosolver.solver.variables.events.IEventType;
import org.chocosolver.solver.variables.impl.scheduler.GraphEvtScheduler;
import org.chocosolver.util.iterators.EvtScheduler;
import org.chocosolver.util.objects.graphs.IGraph;
import org.chocosolver.util.objects.setDataStructures.ISet;
public abstract class AbstractGraphVar extends AbstractVariable implements GraphVar {
//////////////////////////////// GRAPH PART /////////////////////////////////////////
//***********************************************************************************
// VARIABLES
//***********************************************************************************
protected E UB, LB;
protected GraphDelta delta;
protected int n;
///////////// Attributes related to Variable ////////////
protected boolean reactOnModification;
//***********************************************************************************
// CONSTRUCTORS
//***********************************************************************************
/**
* Creates a graph variable
*
* @param solver
*/
protected AbstractGraphVar(String name, Model solver, E LB, E UB) {
super(name, solver);
this.LB = LB;
this.UB = UB;
this.n = UB.getNbMaxNodes();
assert n == LB.getNbMaxNodes();
}
//***********************************************************************************
// METHODS
//***********************************************************************************
@Override
public boolean isInstantiated() {
if (getPotentialNodes().size() != getMandatoryNodes().size()) {
return false;
}
ISet suc;
for (int i : getUB().getNodes()) {
suc = UB.getSuccessorsOf(i);
if (suc.size() != getLB().getSuccessorsOf(i).size()) {
return false;
}
}
return true;
}
/**
* Remove node x from the domain
* Removes x from the upper bound graph
*
* @param x node's index
* @param cause algorithm which is related to the removal
* @return true iff the removal has an effect
*/
public boolean removeNode(int x, ICause cause) throws ContradictionException {
assert cause != null;
assert (x >= 0 && x < n);
if (LB.getNodes().contains(x)) {
this.contradiction(cause, "remove mandatory node");
return true;
} else if (!UB.getNodes().contains(x)) {
return false;
}
int[] succ = UB.getSuccessorsOf(x).toArray();
int[] pred = UB.getPredecessorsOf(x).toArray();
if (UB.removeNode(x)) {
if (reactOnModification) {
delta.add(x, GraphDelta.NODE_REMOVED, cause);
for (int i : succ) {
delta.add(x, GraphDelta.EDGE_REMOVED_TAIL, cause);
delta.add(i, GraphDelta.EDGE_REMOVED_HEAD, cause);
}
for (int i : pred) {
delta.add(i, GraphDelta.EDGE_REMOVED_TAIL, cause);
delta.add(x, GraphDelta.EDGE_REMOVED_HEAD, cause);
}
}
if (succ.length > 0 || pred.length > 0) {
notifyPropagators(GraphEventType.REMOVE_EDGE, cause);
}
notifyPropagators(GraphEventType.REMOVE_NODE, cause);
return true;
}
return false;
}
/**
* Enforce the node x to belong to any solution
* Adds x to the lower bound graph
*
* @param x node's index
* @param cause algorithm which is related to the modification
* @return true iff the enforcing has an effect
*/
public boolean enforceNode(int x, ICause cause) throws ContradictionException {
assert cause != null;
assert (x >= 0 && x < n);
if (UB.getNodes().contains(x)) {
if (LB.addNode(x)) {
if (reactOnModification) {
delta.add(x, GraphDelta.NODE_ENFORCED, cause);
}
notifyPropagators(GraphEventType.ADD_NODE, cause);
return true;
}
return false;
}
this.contradiction(cause, "enforce node which is not in the domain");
return true;
}
@Override
public boolean removeEdge(int x, int y, ICause cause) throws ContradictionException {
assert cause != null;
if (LB.containsEdge(x, y)) {
this.contradiction(cause, "remove mandatory edge");
return false;
}
if (UB.removeEdge(x, y)) {
if (reactOnModification) {
delta.add(x, GraphDelta.EDGE_REMOVED_TAIL, cause);
delta.add(y, GraphDelta.EDGE_REMOVED_HEAD, cause);
}
notifyPropagators(GraphEventType.REMOVE_EDGE, cause);
return true;
}
return false;
}
@Override
public boolean enforceEdge(int x, int y, ICause cause) throws ContradictionException {
assert cause != null;
boolean addX = !LB.containsNode(x);
boolean addY = !LB.containsNode(y);
if (UB.containsEdge(x, y)) {
if (LB.addEdge(x, y)) {
if (reactOnModification) {
delta.add(x, GraphDelta.EDGE_ENFORCED_TAIL, cause);
delta.add(y, GraphDelta.EDGE_ENFORCED_HEAD, cause);
if (addX) {
delta.add(x, GraphDelta.NODE_ENFORCED, cause);
}
if (addY) {
delta.add(y, GraphDelta.NODE_ENFORCED, cause);
}
}
if (addX || addY) {
notifyPropagators(GraphEventType.ADD_NODE, cause);
}
notifyPropagators(GraphEventType.ADD_EDGE, cause);
return true;
}
return false;
}
this.contradiction(cause, "enforce edge which is not in the domain");
return false;
}
//***********************************************************************************
// ACCESSORS
//***********************************************************************************
/**
* @return the lower bound graph (having mandatory nodes and edges)
*/
public E getLB() {
return LB;
}
/**
* @return the upper bound graph (having possible nodes and edges)
*/
public E getUB() {
return UB;
}
/**
* @return the maximum number of node the graph variable may have.
* Nodes are comprised in the interval [0,getNbMaxNodes()]
* Therefore, any vertex should be strictly lower than getNbMaxNodes()
*/
public int getNbMaxNodes() {
return n;
}
//***********************************************************************************
// VARIABLE STUFF
//***********************************************************************************
@Override
public GraphDelta getDelta() {
return delta;
}
@Override
public int getTypeAndKind() {
return VAR | GRAPH;
}
@Override
public EvtScheduler createScheduler() {
return new GraphEvtScheduler();
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("graph_var ").append(getName());
if (isInstantiated()) {
sb.append("\nValue: \n");
sb.append(UB.toString());
} else {
sb.append("\nUpper bound: \n");
sb.append(UB.toString());
sb.append("\nLower bound: \n");
sb.append(LB.toString());
}
return sb.toString();
}
@Override
public void createDelta() {
if (!reactOnModification) {
reactOnModification = true;
delta = new GraphDelta(getEnvironment());
}
}
@Override
public void notifyPropagators(IEventType event, ICause cause) throws ContradictionException {
assert cause != null;
model.getSolver().getEngine().onVariableUpdate(this, event, cause);
notifyMonitors(event);
notifyViews(event, cause);
}
//***********************************************************************************
// SOLUTIONS : STORE AND RESTORE
//***********************************************************************************
@Override
public void instantiateTo(E value, ICause cause) throws ContradictionException {
ISet nodes = value.getNodes();
for (int i = 0; i < n; i++) {
if (nodes.contains(i)) {
enforceNode(i, cause);
} else {
removeNode(i, cause);
}
}
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
if (nodes.contains(i) && nodes.contains(j)) {
if (value.getSuccessorsOf(i).contains(j)) {
enforceEdge(i, j, cause);
} else {
removeEdge(i, j, cause);
}
}
}
}
}
/**
* @return the value of the graph variable represented through an adjacency matrix
* plus a set of nodes (last row of the matrix).
* This method is not supposed to be used except for restoring solutions.
*/
public boolean[][] getValueAsBoolMatrix() {
int n = getUB().getNbMaxNodes();
boolean[][] vals = new boolean[n + 1][n];
for (int i : getLB().getNodes()) {
for (int j : getLB().getSuccessorsOf(i)) {
vals[i][j] = true; // edge in
}
vals[n][i] = true; // node in
}
return vals;
}
/**
* Instantiates this to value which represents an adjacency
* matrix plus a set of nodes (last row of the matrix).
* This method is not supposed to be used except for restoring solutions.
*
* @param value value of this
* @param cause
* @throws ContradictionException if the edge was mandatory
*/
public void instantiateTo(boolean[][] value, ICause cause) throws ContradictionException {
int n = value.length - 1;
for (int i = 0; i < n; i++) {
if (value[n][i]) {//nodes
enforceNode(i, cause);
} else {
removeNode(i, cause);
}
for (int j = 0; j < n; j++) {
if (value[i][j]) {//edges
enforceEdge(i, j, cause);
} else {
removeEdge(i, j, cause);
}
}
}
}
@Override
public IGraphDeltaMonitor monitorDelta(ICause propagator) {
createDelta();
return new GraphDeltaMonitor(getDelta(), propagator);
}
}