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package jrummikub.ai.fdsolver;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
public class Var<T> implements Comparable<Var<T>> {
private Solver solver;
private HashSet<T> range;
private HashSet<Constraint> constraints;
private T recorded;
public Var(Solver solver, Collection<T> range) {
this.solver = solver;
this.range = new HashSet<T>(range);
constraints = new HashSet<Constraint>();
}
public T getValue() {
if (range.size() != 1)
return null;
return range.iterator().next();
}
public HashSet<T> getRange() {
return range;
}
void choose(T value) {
for (Iterator<T> i = this.iterator(); i.hasNext();) {
if (i.next() != value) {
i.remove();
}
}
}
void makeDirty() {
this.solver.dirtyVars.add(this);
}
void invalidate(T value) {
range.remove(value);
solver.logInvalidation(this, value);
makeDirty();
}
HashSet<Constraint> getConstraints() {
return constraints;
}
public Iterator<T> iterator() {
final Iterator<T> iterator = range.iterator();
return new Iterator<T>() {
T lastValue;
@Override
public boolean hasNext() {
return iterator.hasNext();
}
@Override
public T next() {
lastValue = iterator.next();
return lastValue;
}
@Override
public void remove() {
// TODO logging
iterator.remove();
solver.logInvalidation(Var.this, lastValue);
makeDirty();
if (range.size() == 0) {
solver.contradiction = true;
}
}
};
}
void record() {
recorded = getValue();
}
void restore() {
range.clear();
range.add(recorded);
}
@Override
public String toString() {
return "Var" + range;
}
private int neighborCount() {
int count = 0;
for (Constraint constraint : constraints) {
count += constraint.getWatchedVars().size();
}
return count;
}
@Override
public int compareTo(Var<T> other) {
int rangeCompare = ((Integer)range.size()).compareTo(other.range.size());
if (rangeCompare != 0)
return rangeCompare;
return ((Integer)neighborCount()).compareTo(other.neighborCount());
}
}
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