--- a/BinaryTree.st	Wed Oct 01 20:20:35 2008 +0200
+++ b/BinaryTree.st	Thu Oct 09 11:25:06 2008 +0200
@@ -115,6 +115,46 @@
     Transcript show:'Time to remove selectors from BinaryTree: '; show:t2; showCR:'ms'.
                                                                 [exEnd]
 
+  A functional example of a UCB-CS61A lecture's example.
+  The task is to extract all values within a given range (min..max) from
+  a binary tree.
+  The range 'function' below does this; given a binary tree, a min and max value,
+      range(bst, min, max)
+  returns an array of all values which are within that range.
+  Only the relevant branches of the binary tree are to be visited, of course.
+                                                                [exBegin]
+    |t rangeNode range|
+
+    t := BinaryTree new.
+    t add:54; add:37; add:19; add:45; add:80; add:65; add:91; add:57.
+
+    rangeNode := [:node :min :max |
+                |nodeValue leftTree rightTree left right middle|
+
+                leftTree := node leftSubtree.
+                rightTree := node rightSubtree.
+                nodeValue := node data.
+
+                left := (leftTree notNil and:[nodeValue > min]) 
+                            ifTrue:[ rangeNode value:leftTree value:min value:max ]
+                            ifFalse:[ #() ].
+
+                right := (rightTree notNil and:[nodeValue < max]) 
+                            ifTrue:[ rangeNode value:rightTree value:min value:max ]
+                            ifFalse:[ #() ].
+
+                middle := (nodeValue between:min and:max)
+                            ifTrue:[ (Array with:nodeValue) ]    
+                            ifFalse:[ #() ].
+
+                left, middle, right
+        ].
+    range := [:tree :min :max |
+                rangeNode value:tree rootNode value:min value:max
+        ].
+    range value:t value:30 value:60.                
+                                                                [exEnd]
+
 "
 ! !
 
@@ -134,6 +174,10 @@
 
 !BinaryTree methodsFor:'accessing'!
 
+rootNode
+    ^ treeRoot
+!
+
 sortBlock:something
     "set the sort block.
      This is allowed only before any elements are stored in the tree"
@@ -808,5 +852,5 @@
 !BinaryTree class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libbasic2/BinaryTree.st,v 1.6 2007-12-06 21:51:49 stefan Exp $'
+    ^ '$Header: /cvs/stx/stx/libbasic2/BinaryTree.st,v 1.7 2008-10-09 09:25:06 cg Exp $'
 ! !