/** an element which can produce one of several alternatives */
public class Union extends Element implements Iterable<Sequence> {
+ /** display form for the Union (ie not including the RHS) */
final String shortForm;
+
+ /** this is just a hint to use when printing out the grammar in visual form */
final boolean synthetic;
+
+ /** the actual alternatives */
private final List<Sequence> alternatives = new ArrayList<Sequence>();
public Iterator<Sequence> iterator() { return alternatives.iterator(); }
-
- void reachable(HashSet<Sequence.Position> h) { for(Sequence s : alternatives) s.reachable(h); }
+ public boolean contains(Sequence s) { return alternatives.contains(s); }
/** adds an alternative */
- public void add(Sequence s) { alternatives.add(s); }
+ public void add(Sequence s) {
+ alternatives.add(s);
+ for(Sequence n : s.needs) add(n);
+ for(Sequence n : s.hates) add(n);
+ }
/**
* Since every cycle in a non-degenerate grammar contains at