/** 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
this.synthetic = synthetic;
}
+ public static Union epsilon = new Union("()");
+ static { epsilon.add(Sequence.empty); }
+
private Forest.Ref epsilonForm = null;
Forest epsilonForm() {
if (epsilonForm != null) return epsilonForm;
public String toString() { return shortForm; }
private static String pad(int i,String s) { return s.length() >= i ? s : pad(i-1,s)+" "; }
- void toString(StringBuffer sb) {
+ public void toString(StringBuffer sb) {
if (synthetic) return;
boolean first = true;
if (alternatives.size()==0) {