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package solver.constraints.binary;
import gnu.trove.map.hash.THashMap;
import solver.Solver;
import solver.constraints.Propagator;
import solver.constraints.PropagatorPriority;
import solver.exception.ContradictionException;
import solver.explanations.Deduction;
import solver.explanations.Explanation;
import solver.explanations.VariableState;
import solver.variables.IntVar;
import solver.variables.Variable;
import solver.variables.events.IntEventType;
import util.ESat;
/**
* X + Y >= C
* <br/>
*
* @author Charles Prud'homme
* @since 13/06/12
*/
public final class PropGreaterOrEqualXY_C extends Propagator<IntVar> {
final IntVar x;
final IntVar y;
final int cste;
@SuppressWarnings({"unchecked"})
public PropGreaterOrEqualXY_C(IntVar[] vars, int c) {
super(vars, PropagatorPriority.BINARY, true);
this.x = vars[0];
this.y = vars[1];
this.cste = c;
}
@Override
public int getPropagationConditions(int vIdx) {
return IntEventType.INSTANTIATE.getMask() + IntEventType.DECUPP.getMask();
}
@Override
public void propagate(int evtmask) throws ContradictionException {
x.updateLowerBound(this.cste - y.getUB(), aCause);
y.updateLowerBound(this.cste - x.getUB(), aCause);
if (x.getLB() + y.getLB() >= this.cste) {
this.setPassive();
}
}
@Override
public void propagate(int idxVarInProp, int mask) throws ContradictionException {
if (idxVarInProp == 0) {
y.updateLowerBound(this.cste - x.getUB(), aCause);
} else {
x.updateLowerBound(this.cste - y.getUB(), aCause);
}
if (x.getLB() + y.getLB() >= this.cste) {
this.setPassive();
}
}
@Override
public ESat isEntailed() {
if (x.getUB() + y.getUB() < cste)
return ESat.FALSE;
else if (x.getLB() + y.getLB() >= this.cste)
return ESat.TRUE;
else
return ESat.UNDEFINED;
}
@Override
public String toString() {
StringBuilder st = new StringBuilder();
st.append(x.getName()).append(" + ").append(y.getName()).append(" >= ").append(cste);
return st.toString();
}
@Override
public void explain(Deduction d, Explanation e) {
e.add(solver.getExplainer().getPropagatorActivation(this));
e.add(aCause);
// the current deduction is due to the current domain of the involved variables
Variable var = d.getVar();
if (var.equals(x)) {
// a deduction has been made on x ; this is related to y only
y.explain(VariableState.UB, e);
} else if (var.equals(y)) {
x.explain(VariableState.UB, e);
} else {
super.explain(d, e);
}
}
@Override
public void duplicate(Solver solver, THashMap<Object, Object> identitymap) {
if (!identitymap.containsKey(this)) {
this.vars[0].duplicate(solver, identitymap);
IntVar X = (IntVar) identitymap.get(this.vars[0]);
this.vars[1].duplicate(solver, identitymap);
IntVar Y = (IntVar) identitymap.get(this.vars[1]);
identitymap.put(this, new PropGreaterOrEqualXY_C(new IntVar[]{X, Y}, this.cste));
}
}
}