X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FForest.java;h=1730f607eba82daeb513f88053b53d08137a33e2;hb=a82ff8c049dd265ecf1d115d60e1be8ecb81a4c1;hp=04e06be6d80646a17e87494cf363a586a5bf6a5d;hpb=a8478f5ddfbfbc8d910d09f27163cbd55752d3b6;p=sbp.git

diff --git a/src/edu/berkeley/sbp/Forest.java b/src/edu/berkeley/sbp/Forest.java
index 04e06be..1730f60 100644
--- a/src/edu/berkeley/sbp/Forest.java
+++ b/src/edu/berkeley/sbp/Forest.java
@@ -23,7 +23,7 @@ public abstract class Forest<NodeType> implements GraphViz.ToGraphViz {
     public void expand(HashSet<Tree<NodeType>> ht) { expand(ht, new HashSet<Forest<NodeType>>(), null); }
 
     static <NodeType> Forest<NodeType> create(Input.Region loc, NodeType head, Forest<NodeType>[] children, boolean lift) {
-        if (loc == null) throw new Error();
+        if (loc == null) throw new RuntimeException("invoked Forest.create(null,,,,) -- this should never happen");
         return new One<NodeType>(loc, head, children, lift);
     }
 
@@ -57,6 +57,7 @@ public abstract class Forest<NodeType> implements GraphViz.ToGraphViz {
         private One(Input.Region loc, NodeType head, Forest<NodeType>[] children, boolean lift) {
             this.location = loc;
             this.head = head;
+            if (head==null) throw new RuntimeException("invoked Forest.create(,null,,,) -- this should never happen");
             this.children = children==null ? emptyForestArray : new Forest[children.length];
             if (children != null) System.arraycopy(children, 0, this.children, 0, children.length);
             if (children != null) for(int i=0; i<children.length; i++) if (children[i]==null) throw new Error(i+"");
@@ -129,7 +130,6 @@ public abstract class Forest<NodeType> implements GraphViz.ToGraphViz {
     /** An "ambiguity node"; this is immutable once it has been "looked at" */
     static class Many<NodeType> extends Forest<NodeType> {
 
-        HashSet<Node> parents = new HashSet<Node>();
         private FastSet<Forest<NodeType>> hp = new FastSet<Forest<NodeType>>();
         private boolean touched = false;