checkpoint

[sbp.git] / src / edu / berkeley / sbp / Element.java

diff --git a/src/edu/berkeley/sbp/Element.java b/src/edu/berkeley/sbp/Element.java
index b440257..c94adbd 100644 (file)
--- a/src/edu/berkeley/sbp/Element.java
+++ b/src/edu/berkeley/sbp/Element.java
@@ -10,13 +10,11 @@ import java.lang.ref.*;
 /** the root superclass for all components of the grammar (terminals, nonterminals, literals, etc) */
 public abstract class Element {
 
-    /** add all positions reachable from the start of this Element to @rp */
-    abstract void reachable(HashSet<Sequence.Position> rp);
-
+    /** if this element always matches exactly one token, return a topology covering exactly those possible tokens, otherwise <tt>null</tt> */
     abstract Topology toAtom();
-    public Topology noFollow() { return null; }
+
     Forest epsilonForm() { throw new Error("no epsilon form: " + this); }
-    final boolean possiblyEpsilon(Walk.Cache cache)   {
+    final boolean possiblyEpsilon(Walk.Cache cache) {
         Boolean ret = cache==null ? null : cache.possiblyEpsilon.get(this);
         if (ret != null) return ret.booleanValue();
         ret = new Walk.PossiblyEpsilon().walk(this) ? Boolean.TRUE : Boolean.FALSE;