added Element.toAtom()

[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 b199a23..5f55be6 100644 (file)
--- a/src/edu/berkeley/sbp/Element.java
+++ b/src/edu/berkeley/sbp/Element.java
@@ -13,6 +13,7 @@ public abstract class Element {
     /** add all positions reachable from the start of this Element to @rp */
     abstract void reachable(HashSet<Sequence.Position> rp);
 
+    abstract Topology toAtom();
     Forest epsilonForm() { throw new Error("no epsilon form: " + this); }
     final boolean possiblyEpsilon(Walk.Cache cache)   {
         Boolean ret = cache==null ? null : cache.possiblyEpsilon.get(this);