/**
* Returns whether the sets are disjoint.
*
* <p>XXX bogus for empty sets
*/
public static boolean areDisjoint(Set<?>... ss) {
if (ss == null || ss.length == 0) return true;
int elementCount = 0;
for (Set<?> set : ss) {
elementCount += set.size();
}
return CollectionsExt.union(ss).size() == elementCount;
}
/**
* Creates a set of all sequences of length max of objects. The order matters and elements may be
* repeated. The set is grouped by the number of objects in the array. The result is a map from
* arities to object sequences.
*
* <p>NOTE: This is done with arrays rather than lists because in JOE we don't want to execute any
* code of the objects.
*/
public static Map<Integer, Set<Object[]>> createPerArityGroups(Object[] objects, int max) {
Map<Integer, Set<Object[]>> result = new LinkedHashMap<Integer, Set<Object[]>>();
result.put(0, Collections.singleton(new Object[0]));
for (int i = 1; i <= max; i++) {
Set<Object[]> newSet = new LinkedHashSet<Object[]>();
// add each object to each one smaller
for (Object[] oneSmaller : result.get(i - 1)) {
for (Object object : objects) {
newSet.add(CollectionsExt.addToArray(oneSmaller, object));
}
}
result.put(i, newSet);
}
return result;
}