X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FUnion.java;h=8780d9ea02df515179df4827dc41658897cc3681;hp=7274dae01ff36d1036dcaebbc99cf471e80fa315;hb=96a2822a729e563a64173f22dc184bc972a200ef;hpb=2690f6c749f117a103c57d651d89f1b4fbf1316d

diff --git a/src/edu/berkeley/sbp/Union.java b/src/edu/berkeley/sbp/Union.java
index 7274dae..8780d9e 100644
--- a/src/edu/berkeley/sbp/Union.java
+++ b/src/edu/berkeley/sbp/Union.java
@@ -16,16 +16,15 @@ public class Union extends Element implements Iterable<Sequence> {
 
     public Iterator<Sequence> iterator() { return alternatives.iterator(); }
 
-    void reachable(HashSet<Sequence.Position> h) { for(Sequence s : alternatives) s.reachable(h); }
-
     Topology toAtom() {
-        if (alternatives.size()==0) return null;
+        if (alternatives.size()==0) throw new RuntimeException("cannot build an Atom from a Union with no productions");
         Topology ret = null;
         for(Sequence s : this) {
             Topology a = s.toAtom();
-            if (ret==null) ret = a.dup();
-            else           ret.add(a.dup());
+            if (ret==null) ret = a;
+            else           ret = ret.union(a);
         }
+        if (ret==null) throw new RuntimeException("confusion on " + this);
         return ret;
     }