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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.ValueRemoval;
import solver.explanations.VariableState;
import solver.variables.IntVar;
import solver.variables.delta.IIntDeltaMonitor;
import solver.variables.events.IntEventType;
import util.ESat;
import util.procedure.IntProcedure;
/**
* X = Y + C
* <p/>
* <br/>
*
* @author Charles Prud'homme, Jean-Guillaume Fages
* @since 1 oct. 2010
*/
public final class PropEqualX_YC extends Propagator<IntVar> {
private IntVar x, y;
private final int cste;
// incremental filtering of enumerated domains
private boolean bothEnumerated;
private IIntDeltaMonitor[] idms;
private RemProc rem_proc;
private int indexToFilter;
private int offSet;
@SuppressWarnings({"unchecked"})
public PropEqualX_YC(IntVar[] vars, int c) {
super(vars, PropagatorPriority.BINARY, true);
this.x = vars[0];
this.y = vars[1];
this.cste = c;
if (x.hasEnumeratedDomain() && y.hasEnumeratedDomain()) {
bothEnumerated = true;
idms = new IIntDeltaMonitor[2];
idms[0] = vars[0].monitorDelta(this);
idms[1] = vars[1].monitorDelta(this);
rem_proc = new RemProc();
}
}
@Override
public int getPropagationConditions(int vIdx) {
if (bothEnumerated)
return IntEventType.all();
else
return IntEventType.boundAndInst();
}
@Override
public void propagate(int evtmask) throws ContradictionException {
updateBounds();
// ensure that, in case of enumerated domains, holes are also propagated
if (bothEnumerated) {
int ub = x.getUB();
for (int val = x.getLB(); val <= ub; val = x.nextValue(val)) {
if (!y.contains(val - cste)) {
x.removeValue(val, aCause);
}
}
ub = y.getUB();
for (int val = y.getLB(); val <= ub; val = y.nextValue(val)) {
if (!x.contains(val + cste)) {
y.removeValue(val, aCause);
}
}
idms[0].unfreeze();
idms[1].unfreeze();
}
if (x.isInstantiated()) {
assert (y.isInstantiated());
setPassive();
}
}
@Override
public void propagate(int varIdx, int mask) throws ContradictionException {
updateBounds();
if (x.isInstantiated()) {
assert (y.isInstantiated());
setPassive();
} else if (bothEnumerated) {
if (varIdx == 0) {
indexToFilter = 1;
offSet = -cste;
} else {
indexToFilter = 0;
offSet = cste;
}
idms[varIdx].freeze();
idms[varIdx].forEachRemVal(rem_proc);
idms[varIdx].unfreeze();
}
}
private void updateBounds() throws ContradictionException {
while (x.updateLowerBound(y.getLB() + cste, aCause) | y.updateLowerBound(x.getLB() - cste, aCause)) ;
while (x.updateUpperBound(y.getUB() + cste, aCause) | y.updateUpperBound(x.getUB() - cste, aCause)) ;
}
@Override
public ESat isEntailed() {
if ((x.getUB() < y.getLB() + cste) ||
(x.getLB() > y.getUB() + cste) ||
x.hasEnumeratedDomain() && y.hasEnumeratedDomain() && !match())
return ESat.FALSE;
else if (x.isInstantiated() &&
y.isInstantiated() &&
(x.getValue() == y.getValue() + cste))
return ESat.TRUE;
else
return ESat.UNDEFINED;
}
private boolean match() {
int lb = x.getLB();
int ub = x.getUB();
for (; lb <= ub; lb = x.nextValue(lb)) {
if (y.contains(lb - cste)) return true;
}
return false;
}
@Override
public void explain(Deduction d, Explanation e) {
// return super.explain(d);
if (d.getVar() == x) {
e.add(solver.getExplainer().getPropagatorActivation(this));
e.add(this);
if (d.getmType() == Deduction.Type.ValRem) {
y.explain(VariableState.REM, ((ValueRemoval) d).getVal() - cste, e);
} else {
throw new UnsupportedOperationException("PropEqualXY only knows how to explain ValueRemovals");
}
} else if (d.getVar() == y) {
e.add(solver.getExplainer().getPropagatorActivation(this));
e.add(this);
if (d.getmType() == Deduction.Type.ValRem) {
x.explain(VariableState.REM, ((ValueRemoval) d).getVal() + cste, e);
} else {
throw new UnsupportedOperationException("PropEqualXY only knows how to explain ValueRemovals");
}
} 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 PropEqualX_YC(new IntVar[]{X, Y}, this.cste));
}
}
@Override
public String toString() {
StringBuilder bf = new StringBuilder();
bf.append("prop(").append(vars[0].getName()).append(".EQ.").append(vars[1].getName());
if (cste != 0) {
bf.append("+").append(cste);
}
bf.append(")");
return bf.toString();
}
private class RemProc implements IntProcedure {
@Override
public void execute(int i) throws ContradictionException {
vars[indexToFilter].removeValue(i + offSet, aCause);
}
}
}