@SuppressWarnings("unchecked")
public static <T extends HGQueryCondition> T collapse(HyperGraph graph, Set<HGQueryCondition> S) {
if (S == null || S.isEmpty()) return null;
Iterator<HGQueryCondition> I = S.iterator();
HGQueryCondition c = I.next();
while (I.hasNext()) if (!c.equals(I.next())) throw new ContradictoryCondition();
return (T) c;
}
/**
* Collect and group different types of conditions in map. The method takes any number of
* condition Class-es and return a map Class->Set<all conditions of that class>. The test is done
* using the <code>Class.isAssignableFrom</code> so a given condition could end in multiple map
* entries if some of the Class arguments inherit from each other. If no condition of a specified
* Class is found, the map won't contain an entry for that class at all.
*
* @param C
* @param condType
* @return
*/
public static Map<Class<?>, Set<HGQueryCondition>> find(
Collection<HGQueryCondition> C, Class<?>... condType) {
HashMap<Class<?>, Set<HGQueryCondition>> M = new HashMap<Class<?>, Set<HGQueryCondition>>();
for (HGQueryCondition c : C) {
for (int i = 0; i < condType.length; i++)
if (condType[i].isAssignableFrom(c.getClass())) {
Set<HGQueryCondition> S = M.get(condType[i]);
if (S == null) {
S = new HashSet<HGQueryCondition>();
M.put(condType[i], S);
}
S.add(c);
}
}
return M;
}