X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FUnion.java;h=c1642627c0dac9d744973d40a0c904f7369ceea4;hp=1843a4620cb5dd2ca96b92636ce4c332883230e9;hb=dc9bb3a45ed306e2e35549076842b3e74efecb48;hpb=449c39e0dafd7c736bfcd8d56bbd08b7a99e25a4

diff --git a/src/edu/berkeley/sbp/Union.java b/src/edu/berkeley/sbp/Union.java
index 1843a46..c164262 100644
--- a/src/edu/berkeley/sbp/Union.java
+++ b/src/edu/berkeley/sbp/Union.java
@@ -26,7 +26,8 @@ public class Union extends Element implements Iterable<Sequence> {
     private final List<Sequence> alternatives = new ArrayList<Sequence>();
 
     public Union(String name) { this(name, false); }
-    public Union(String name, Sequence s) { this(name, false); add(s); }
+    public Union(String name, Sequence s) { this(name, s, false); }
+    public Union(String name, Sequence s, boolean synthetic) { this(name, synthetic); add(s); }
 
     /**
      *  Since every cycle in a non-degenerate grammar contains at
@@ -72,19 +73,13 @@ public class Union extends Element implements Iterable<Sequence> {
         add(Sequence.create(e));
     }
 
-
-    // Epsilon Form //////////////////////////////////////////////////////////////////////////////
-
-    private Forest.Many epsilonForm = null;
-    Forest epsilonForm(Input.Region loc) {
-        // FIXME: this is pretty ugly...
+    /** the Forest which results from matching this Union against the empty string at region <tt>region</tt> */
+    Forest epsilonForm(Input.Region region, Cache cache) {
         viewed = true;
-        if (epsilonForm != null) return epsilonForm;
         Forest.Many epsilonForm = new Forest.Many();
-        Cache cache = new Cache(null, null);
         for(Sequence s : this)
             if (cache.possiblyEpsilon(s))
-                epsilonForm.merge(s.epsilonForm(loc));
+                epsilonForm.merge(s.epsilonForm(region, cache));
         return epsilonForm;
     }