X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FElement.java;h=c94adbdcc6f80a3ed43822c8b632b1fef16dc0b5;hp=7e140f9a2f93b093a9ec2485cdd510d42aee3e9e;hb=888e9ccbab5f458a727c16da9d9291fd8951d909;hpb=84a4a8204373b996105e69edf91d2f9fae7b4bcb

diff --git a/src/edu/berkeley/sbp/Element.java b/src/edu/berkeley/sbp/Element.java
index 7e140f9..c94adbd 100644
--- a/src/edu/berkeley/sbp/Element.java
+++ b/src/edu/berkeley/sbp/Element.java
@@ -10,10 +10,11 @@ import java.lang.ref.*;
 /** the root superclass for all components of the grammar (terminals, nonterminals, literals, etc) */
 public abstract class Element {
 
+    /** 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;