Implement rtree-length.

diff --git a/lisp/rtree.el b/lisp/rtree.el
index b3e21f3..d2aa918 100644 (file)
--- a/lisp/rtree.el
+++ b/lisp/rtree.el
@@ -265,6 +265,15 @@
        (setq tree (rtree-left tree))))
     result))
 
+(defun rtree-length (tree)
+  "Return the number of numbers stored in TREE."
+  (if (null tree)
+      0
+    (+ (rtree-length (rtree-left tree))
+       (1+ (- (rtree-high tree)
+             (rtree-low tree)))
+       (rtree-length (rtree-right tree)))))
+
 (provide 'rtree)
 
 ;;; rtree.el ends here