;;;-*- Mode: LISP; Syntax: Common-Lisp; Base: 10; Package: COMMON-LISP-USER -*-

;;; $Id: treeprint.lisp,v 1.1 1994/11/09 20:05:48 lyman Exp lyman $
;;; $Revision: 1.1 $

;;;; Overview

;;; Author: Lyman Taylor ( lyman@cc.gatech.edu )
;;; Company: Buckaroo Banzai Institute
;;; 
;;;
;;;

;;; If you have the selectors (left-child , right-child ) and 
;;; predicate (empty-tree-p )used by this function you
;;; can print you trees "sideways".  Namely the root will
;;; appears leftmost and the "leaves" appear rightmost.
;;; Rotating your head 90 degress counterclockwise will show the tree 
;;; structure.
;;; 

(defun tree-print ( tree &optional ( depth  0 ) )
  "This is print out the nodes of a tree by doing an 'reverse order' traversal.
   It is actually in reverse order so the when result is rotated 90 degrees
   clockwise the left-child will appear on the left."
   (let ((format-string (if (= depth 0 )
			   (format nil "~%  ~~A")
			   (format nil "~% ~~~A,8T ~~A" (* depth 8 ) ))))
     (cond ((empty-tree-p tree ) nil )
	   ( t   (tree-print (right-child tree ) (1+ depth))
		 (format *query-io* format-string (tree-key tree ))
		 (tree-print (left-child tree) (1+ depth))))))

  

;;; EOF
;;;;;;;