/**
* Copyright (c) 1999-2014, Ecole des Mines de Nantes
* All rights reserved.
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * 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.
* * Neither the name of the Ecole des Mines de Nantes nor the
* 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
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE REGENTS AND CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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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 PropMin extends Propagator<IntVar> {
final int n;
public PropMin(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 ub = vars[n].getUB()+1;
int lb = ub;
// update min
for(int i=0; i<n; i++){
lb = Math.min(lb,vars[i].getLB());
ub = Math.min(ub,vars[i].getUB());
}
vars[n].updateLowerBound(lb,aCause);
vars[n].updateUpperBound(ub,aCause);
lb = vars[n].getLB();
// back-propagation
for(int i=0; i<n; i++){
if(vars[i].getLB()<=ub){
idx=idx==-1?i:-2;
vars[i].updateLowerBound(lb,aCause);
}
}
if(idx>=0){
if(vars[idx].updateUpperBound(ub,aCause) && lb==ub){ // entailed
setPassive();
}
}
}
@Override
public ESat isEntailed() {
int lb = vars[n].getLB();
for(int i=0; i<n; i++){
if(vars[i].getUB()<lb){
return ESat.FALSE;
}
}
for(int i=0; i<n; i++){
if(vars[i].getLB()<lb){
return ESat.UNDEFINED;
}
}
if(vars[n].isInstantiated()){
for(int i=0; i<n; i++){
if(vars[i].isInstantiatedTo(lb)){
return ESat.TRUE;
}
}
}
return ESat.UNDEFINED;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder("PropMin ");
sb.append(vars[n]).append(" = min({");
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 PropMin(aVars, M));
}
}
}