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package jrummikub.ai.fdsolver.constraint;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.locks.Condition;
import jrummikub.ai.fdsolver.Constraint;
import jrummikub.ai.fdsolver.Propagator;
import jrummikub.ai.fdsolver.Satisfiability;
import jrummikub.ai.fdsolver.Var;
public class IfConstraint extends Constraint {
Var<Boolean> condition;
Constraint child;
Collection<Var<?>> vars;
boolean negateCond;
public IfConstraint(boolean negateCond, Var<Boolean> condition, Constraint child) {
this.condition = condition;
this.child = child;
this.negateCond = negateCond;
vars = new ArrayList<Var<?>>();
vars.addAll(child.getWatchedVars());
vars.add(condition);
}
@Override
public Collection<Var<?>> getWatchedVars() {
return vars;
}
private class IfPropagator implements Propagator {
Propagator child;
Collection<Var<?>> vars;
public IfPropagator(Propagator child) {
this.child = child;
vars = new ArrayList<Var<?>>();
vars.addAll(child.getWatchedVars());
vars.add(condition);
}
@Override
public Collection<Var<?>> getWatchedVars() {
return vars;
}
@Override
public void propagate() {
if(condition.getRange().contains(negateCond)) {
return;
}
child.propagate();
}
}
private class FailPropagator implements Propagator {
@Override
public Collection<Var<?>> getWatchedVars() {
return child.getWatchedVars();
}
@Override
public void propagate() {
if (!child.isSatisfiable()) {
condition.invalidate(!negateCond);
}
}
}
@Override
public Collection<Propagator> getPropagators(boolean negate) {
List<Propagator> props = new ArrayList<Propagator>();
if (negate) {
props.add(new FilterPropagator<Boolean>(new Filter<Boolean>() {
@Override
public boolean accept(Boolean value) {
return value ^ negateCond;
}
}, condition));
props.addAll(child.getPropagators(true));
} else {
for (Propagator p : child.getPropagators(false)) {
props.add(new IfPropagator(p));
}
props.add(new FailPropagator());
}
return props;
}
@Override
public Satisfiability getSatisfiability() {
if (condition.getRange().contains(negateCond)) {
if (condition.getRange().size() == 1) {
return Satisfiability.TAUT;
} else {
if (child.getSatisfiability() == Satisfiability.TAUT) {
return Satisfiability.TAUT;
} else {
return Satisfiability.SAT;
}
}
}
return child.getSatisfiability();
}
}
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