make expand1() use a non-recursive descent function to avoid stack overflows

[sbp.git] / src / edu / berkeley / sbp / Tree.java

diff --git a/src/edu/berkeley/sbp/Tree.java b/src/edu/berkeley/sbp/Tree.java
index ab6ff7a..62dfa9d 100644 (file)
--- a/src/edu/berkeley/sbp/Tree.java
+++ b/src/edu/berkeley/sbp/Tree.java
@@ -12,6 +12,8 @@ public class Tree<NodeType>
     extends PrintableTree<Tree<NodeType>>
     implements Iterable<Tree<NodeType>> {
 
+    private static final Tree[] emptyTree = new Tree[0];
+
     private final Input.Region     location;
     private final NodeType         ihead;
     private final Tree<NodeType>[] children;
@@ -35,8 +37,26 @@ public class Tree<NodeType>
     /** get the input region that this tree was parsed from */
     public Input.Region    getRegion() { return location; }
 
-    public Tree(Input.Region loc, NodeType head)                            { this(loc, head, new Tree[0]); }
-    public Tree(Input.Region loc, NodeType head, Tree<NodeType>[] children) { this(loc, head, children, new boolean[children==null?0:children.length]); }
+    public Tree(Input.Region loc, NodeType head) {
+        location = loc;
+        ihead = head;
+        children = emptyTree;
+    }
+    public Tree(Input.Region loc, NodeType head, List<Tree<NodeType>> kids){
+        location = loc;
+        ihead = head;
+        if (children.size() == 0)
+            children = emptyTree;
+        else {
+            children = new Tree[kids.size()];
+            kids.toArray(children);
+        }
+    }
+    public Tree(Input.Region loc, NodeType head, Tree<NodeType>[] kids) {
+        location = loc;
+        ihead = head;
+        children = (kids == null ? emptyTree : kids.clone());
+    }
 
     // FIXME: fairly inefficient because we keep copying arrays
     /** package-private constructor, allows setting the "lift" bit */