/**
* Copyright (c) 1999-2014, Ecole des Mines de Nantes
* All rights reserved.
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* modification, are permitted provided that the following conditions are met:
*
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* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
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* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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package solver.constraints.nary.min_max;
import gnu.trove.map.hash.THashMap;
import solver.Solver;
import solver.constraints.Propagator;
import solver.constraints.PropagatorPriority;
import solver.exception.ContradictionException;
import solver.variables.IntVar;
import solver.variables.events.IntEventType;
import util.ESat;
import util.tools.ArrayUtils;
/**
* <br/>
*
* @Jean-Guillaume Fages
* @since 15/12/2013
*/
public class PropMax extends Propagator<IntVar> {
final int n;
public PropMax(IntVar[] variables, IntVar maxVar) {
super(ArrayUtils.append(variables, new IntVar[]{maxVar}), PropagatorPriority.LINEAR, false);
n = variables.length;
assert n > 0;
}
@Override
public int getPropagationConditions(int vIdx) {
return IntEventType.boundAndInst();
}
@Override
public void propagate(int evtmask) throws ContradictionException {
int idx = -1;
int lb = vars[n].getLB() - 1;
int ub = lb;
// update max
for (int i = 0; i < n; i++) {
lb = Math.max(lb, vars[i].getLB());
ub = Math.max(ub, vars[i].getUB());
}
vars[n].updateLowerBound(lb, aCause);
vars[n].updateUpperBound(ub, aCause);
ub = vars[n].getUB();
// back-propagation
for (int i = 0; i < n; i++) {
if (vars[i].getUB() >= lb) {
idx = idx == -1 ? i : -2;
vars[i].updateUpperBound(ub, aCause);
}
}
if (idx >= 0) {
if (vars[idx].updateLowerBound(lb, aCause) && lb == ub) { // entailed
setPassive();
}
}
}
@Override
public ESat isEntailed() {
int ub = vars[n].getUB();
for (int i = 0; i < n; i++) {
if (vars[i].getLB() > ub) {
return ESat.FALSE;
}
}
for (int i = 0; i < n; i++) {
if (vars[i].getUB() > ub) {
return ESat.UNDEFINED;
}
}
if (vars[n].isInstantiated()) {
for (int i = 0; i < n; i++) {
if (vars[i].isInstantiatedTo(ub)) {
return ESat.TRUE;
}
}
}
return ESat.UNDEFINED;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder("PropMax ");
sb.append(vars[n]).append(" = max({");
sb.append(vars[0]);
for (int i = 1; i < n; i++) {
sb.append(", ");
sb.append(vars[i]);
}
sb.append("})");
return sb.toString();
}
@Override
public void duplicate(Solver solver, THashMap<Object, Object> identitymap) {
if (!identitymap.containsKey(this)) {
int size = this.vars.length - 1;
IntVar[] aVars = new IntVar[size];
for (int i = 0; i < size; i++) {
this.vars[i].duplicate(solver, identitymap);
aVars[i] = (IntVar) identitymap.get(this.vars[i]);
}
this.vars[size].duplicate(solver, identitymap);
IntVar M = (IntVar) identitymap.get(this.vars[size]);
identitymap.put(this, new PropMax(aVars, M));
}
}
}