Tree.java: resolve any lifting at Tree-creation time

darcs-hash:20070326054504-5007d-f9ec93a73ef92b7fec72900fbbf291c5ce2cd022.gz

diff --git a/src/edu/berkeley/sbp/Tree.java b/src/edu/berkeley/sbp/Tree.java
index d655aa4..bc450fb 100644 (file)
--- a/src/edu/berkeley/sbp/Tree.java
+++ b/src/edu/berkeley/sbp/Tree.java
@@ -3,7 +3,6 @@
 package edu.berkeley.sbp;
 import edu.berkeley.sbp.*;
 import edu.berkeley.sbp.util.*;
-import edu.berkeley.sbp.bind.*;
 import java.io.*;
 import java.util.*;
 import java.lang.reflect.*;
@@ -13,19 +12,12 @@ public class Tree<NodeType>
     extends PrintableTree<Tree<NodeType>>
     implements Iterable<Tree<NodeType>> {
 
-    private final Input.Region location;
-    private final NodeType     ihead;
-    private final Tree<NodeType>[]    children;
-    private final boolean      lift;
-
-    private Tree<NodeType> lifted() { return children[children.length-1]; }
+    private final Input.Region     location;
+    private final NodeType         ihead;
+    private final Tree<NodeType>[] children;
 
     /** the number of children the tree has */
-    public int               size() {
-        return lift
-            ? (children.length-1)+lifted().size()
-            : children.length;
-    }
+    public int               size() { return children.length; }
 
     /** the element at the head of the tree */
     public NodeType                 head()        { return ihead; }
@@ -35,32 +27,31 @@ public class Tree<NodeType>
     public Iterable<Tree<NodeType>> children()    { return this; }
 
     /** the tree's children */
-    public Iterator<Tree<NodeType>> iterator()    {
-        return lift
-            ? new ConcatenateIterator(new ArrayIterator(children, 0, children.length-1),
-                                      children[children.length-1].iterator())
-            : new ArrayIterator(children);
-    }
+    public Iterator<Tree<NodeType>> iterator()    { return new ArrayIterator(children); }
 
     /** get the <tt>i</t>th child */
-    public Tree<NodeType> child(int i)  {
-        return lift && i >= children.length-1
-            ? children[children.length-1].child(i-(children.length-1))
-            : children[i];
-    }
+    public Tree<NodeType> child(int i)            { return children[i]; }
 
     /** 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, null); }
+    public Tree(Input.Region loc, NodeType head)                            { this(loc, head, null); }
     public Tree(Input.Region loc, NodeType head, Tree<NodeType>[] children) { this(loc, head, children, false); }
 
+    // FIXME: fairly inefficient because we keep copying arrays
     /** package-private constructor, allows setting the "lift" bit */
     Tree(Input.Region loc, NodeType head, Tree<NodeType>[] children, boolean lift) {
         this.location = loc;
         this.ihead = head;
-        this.lift = lift && children != null && children.length > 0;
-        this.children = ArrayUtil.clone(children, Tree.class);
+        if (lift && children != null && children.length > 0) {
+            Tree<NodeType> last = children[children.length-1];
+            this.children = new Tree[(children.length-1)+last.children.length];
+            System.arraycopy(children, 0, this.children, 0, children.length-1);
+            if (last.children.length > 0)
+                System.arraycopy(last.children, 0, this.children, children.length-1, last.children.length);
+        } else {
+            this.children = ArrayUtil.clone(children, Tree.class);
+        }
     }