added count function

src/interface.lisp

@@ -31,6 +31,9 @@
   "Tree constructor which selects the appropriate tree type depending on the type keyword."
   (make-tree-intern test type))
 
+(defgeneric treemap-count (tree)
+  (:documentation "Return the number of elements in the tree."))
+
 (defgeneric clr-tree (tree)
   (:documentation "Remove all elements from a tree."))
 

src/package.lisp

@@ -24,6 +24,6 @@
   ;; tree classes
   (:export tree-map redblack-tree-map)
   ;; basic tree operations
-  (:export make-tree get-tree-entry del-tree-entry clr-tree)
+  (:export make-tree get-tree-entry del-tree-entry clr-tree treemap-count)
   ;; split and merge
   (:export split-tree merge-trees))

src/redblack.lisp

@@ -27,6 +27,7 @@
 (defclass redblack-tree-map (tree-map)
   ((data    :accessor data :initform nil
 	    :documentation "A node consists of the values key, data, color, left, right.")
+   (num-elements :accessor num-elements :initform 0)
    (testfun :accessor testfun :initarg :testfun :initform (error "No test function specified.")))
   (:documentation "Red-Black tree."))
 
@@ -138,6 +139,22 @@
     (setf tree (make-instance 'redblack-tree-map :testfun test))))
 
 
+(defmethod treemap-count ((tree redblack-tree-map))
+  "Quick and dirty iterate function. TODO: replace"
+  (let ((num 0))
+    (labels ((recurse-node (node)
+	       (if node
+		   (progn
+		     ;; recurse to the left
+		     (recurse-node (rb-left node))
+		     ;; count this node
+		     (incf num)
+		     ;; recurse to the right
+		     (recurse-node (rb-right node))))))
+      (recurse-node (data tree)))
+    num))
+
+
 (defmethod clr-tree ((tree redblack-tree-map))
   (setf (data tree) nil)
   tree)