/** An "ambiguity node"; this is immutable once it has been "looked at" */
static class Many<NodeType> extends Forest<NodeType> {
- HashSet<GSS.Phase.Node> parents = new HashSet<GSS.Phase.Node>();
private FastSet<Forest<NodeType>> hp = new FastSet<Forest<NodeType>>();
private boolean touched = false;
void gather(HashSet<Forest<NodeType>> ht) {
touched();
+
+ // FIXME: do something more sensible here
+ if (ht.contains(this)) {
+ System.err.println("WARNING: grammar produced a circular forest\n" + this);
+ //throw new Error("grammar produced a circular forest:\n" + this);
+ return;
+ }
+
ht.add(this);
for(Forest<NodeType> f : hp) f.gather(ht);
}