Add initial support for SEQUENCE integration.

[trees.git] / iterator.lisp

diff --git a/iterator.lisp b/iterator.lisp
index 3cdaa1c..e8c7ea9 100644 (file)
--- a/iterator.lisp
+++ b/iterator.lisp
@@ -1,7 +1,7 @@
 (in-package :trees)
 
-(defun extreme-node-with-path (root direction &optional path)
-  (do ((node root (funcall direction node))
+(defun extreme-node-with-path (root leftp &optional path)
+  (do ((node root (if leftp (left node) (right node)))
        (parent nil node))
       ((null node) (values parent path))
     (push node path)))
@@ -12,28 +12,24 @@
                        (stack nil stackp))
   (declare (type binary-tree tree))
   (let ((modcount (modcount tree)))
-    (multiple-value-bind (extremum examine)
-                  (if forwardp
-                      (values #'left #'right)
-                      (values #'right #'left))
-      (multiple-value-bind (current stack)
-          (if (and currentp stackp)
-              (values current stack)
-              (extreme-node-with-path (root tree) extremum))
-        #'(lambda ()
-            (cond
-              ((/= modcount (modcount tree))
-               (error "~A modified during iteration" tree))
-              ((null current)
-               (values nil nil))
-              (t
-               (let* ((next current)
-                      (top (pop stack))
-                      (node (funcall examine top)))
-                 (cond
-                   ((null node)
-                    (setf current (first stack)))
-                   (t
-                    (setf (values current stack)
-                          (extreme-node-with-path node extremum stack))))
-                 (values next t)))))))))
+    (multiple-value-bind (current stack)
+        (if (and currentp stackp)
+            (values current stack)
+            (extreme-node-with-path (root tree) forwardp))
+      (lambda ()
+        (cond
+          ((/= modcount (modcount tree))
+           (error "~A modified during iteration" tree))
+          ((null current)
+           (values nil nil))
+          (t
+           (let* ((next current)
+                  (top (pop stack))
+                  (node (if forwardp (right top) (left top))))
+             (cond
+               ((null node)
+                (setf current (first stack)))
+               (t
+                (setf (values current stack)
+                      (extreme-node-with-path node forwardp stack))))
+             (values next t))))))))