Date: Tue, 1 Nov 88 20:45:45 EST
To: NeWS-makers@brillig.umd.edu
Subject: Graphic display of binary search tree manipulation in NeWS
From: gondor.cs.psu.edu!callahan@psuvax1.psu.edu  (Paul B. Callahan)

The follow shar file contains the code for NeWS window program that allows
the user to "edit" binary search trees.  It is contained in the files
treeedit.c, and treeedit.cps.  The executable csh file cctreeedit will
compile it into treeedit if your system is configured in the same way
as the one I used.

The editor is easy to use.

        The default initial tree is just a single node.

	The left mouse button causes a tree rotation on the edge
	going into a node, if it is clicked directly on the node.
        If it is clicked far away, it allows gradual movement of
	the current node.

	The middle mouse button is used to select the node it is
	clicked on as the current node.

	The right button causes insertion of a node in a place
	determined by the x coordinate of the mouse location.

	Finally, the screen button DELETE deletes the current node.

	When the window is zapped, the c program outputs an RPN
	expression for the tree to stdout.

	This sort of expression can also be input as the current
	tree using the -i option.

Have fun, and reply with any feedback or suggestions.