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 c94adbd..33bfd8d 100644 (file)
--- a/src/edu/berkeley/sbp/Element.java
+++ b/src/edu/berkeley/sbp/Element.java
@@ -10,15 +10,9 @@ import java.lang.ref.*;
 /** the root superclass for all components of the grammar (terminals, nonterminals, literals, etc) */
 public abstract class Element {
 
+    abstract StringBuffer toString(StringBuffer sb);
+
     /** if this element always matches exactly one token, return a topology covering exactly those possible tokens, otherwise <tt>null</tt> */
-    abstract Topology toAtom();
+    Forest epsilonForm() { return null; }
 
-    Forest epsilonForm() { throw new Error("no epsilon form: " + this); }
-    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;
-        if (cache != null) cache.possiblyEpsilon.put(this, ret);
-        return ret;
-    }
 }