public static IList closureStar(IList rel1) {
Type resultType = rel1.getType().closure();
// an exception will have been thrown if the type is not acceptable
IListWriter reflex = List.createListWriter(resultType.getElementType());
for (IValue e : carrier(rel1)) {
reflex.insert(Tuple.newTuple(new IValue[] {e, e}));
}
return closure(rel1).concat(reflex.done());
}
public static IList carrier(IList rel1) {
Type newType = rel1.getType().carrier();
IListWriter w = List.createListWriter(newType.getElementType());
HashSet<IValue> cache = new HashSet<>();
for (IValue v : rel1) {
ITuple t = (ITuple) v;
for (IValue e : t) {
if (!cache.contains(e)) {
cache.add(e);
w.append(e);
}
}
}
return w.done();
}
public static IList closure(IList rel1) {
Type resultType = rel1.getType().closure(); // will throw exception if not binary and reflexive
IList tmp = rel1;
int prevCount = 0;
ShareableValuesHashSet addedTuples = new ShareableValuesHashSet();
while (prevCount != tmp.length()) {
prevCount = tmp.length();
IList tcomp = compose(tmp, tmp);
IListWriter w = List.createListWriter(resultType.getElementType());
for (IValue t1 : tcomp) {
if (!tmp.contains(t1)) {
if (!addedTuples.contains(t1)) {
addedTuples.add(t1);
w.append(t1);
}
}
}
tmp = tmp.concat(w.done());
addedTuples.clear();
}
return tmp;
}