+ protected HashSet<SequenceOrElement> walk2(SequenceOrElement e) {
+ HashSet<SequenceOrElement> ret = super.walk2(e);
+ if (e instanceof Union)
+ for(Sequence s : (Union)e) {
+ for(Sequence ss : s.needs()) ret = union((Union)e, ret, walk(ss));
+ for(Sequence ss : s.hates()) ret = union((Union)e, ret, walk(ss));
+ }
+ return ret;
+ }
+ }
+
+ static class YieldSet2 extends Walk<HashSet<SequenceOrElement>> {
+ private final SequenceOrElement e;
+ public final HashSet<SequenceOrElement> walk() { return walk(e); }
+ public YieldSet2(SequenceOrElement e, Cache c) { super(c); this.e = e; }
+ public HashSet<SequenceOrElement> bottom(SequenceOrElement e) { return acc; }
+ public HashSet<SequenceOrElement> walkSequence(Sequence seq) { return bottom(seq); }
+ public HashSet<SequenceOrElement> walkAtom(Atom r) {
+ c.atoms.put(e, c.atoms.get(e)==null ? r : c.atoms.get(e).union(r));
+ return super.walkAtom(r);
+ }
+ }
+
+ static class EquivalentTo extends Walk<HashSet<Sequence>> {
+ private final Sequence s;
+ private final HashSet<Sequence> eq = new HashSet<Sequence>();
+ public final HashSet<Sequence> walk() { return walk(s); }
+ public EquivalentTo(Sequence e, Cache c) {
+ super(c); this.s = e;
+ }
+ public HashSet<Sequence> bottom(SequenceOrElement e) { return eq; }
+ public HashSet<Sequence> walkSequence(Sequence seq) {
+ eq.add(seq);
+ Position p = seq.firstp();
+ for(; !p.isLast(); p = p.next()) {
+ if (!p.isLast() && isRightNullable(p.next()))
+ walk(p.element());
+ if (!c.possiblyEpsilon(p.element())) break;
+ }
+ return eq;
+ }
+ public HashSet<Sequence> walkAtom(Atom r) {
+ return eq;
+ }
+ private boolean isRightNullable(Position p) {
+ if (p.isLast()) return true;
+ if (!c.possiblyEpsilon(p.element())) return false;
+ return isRightNullable(p.next());
+ }