(defstruct node (name "") (children nil))

(defvar g1 (let* ((2a (make-node :name "2A"))

                  (2b (make-node :name "2B"))

                  (2c (make-node :name "2C"))

                  (1a (make-node :name "1A" :children (list 2a 2b)))

                  (1b (make-node :name "1B" :children (list 2b 2c))))

             (make-node :name "0" :children (list 1a 1b))))

(defun test-graph (root-node &rest keys)

  (apply #'clim:format-graph-from-root root-node

         #'(lambda (node s)

             (write-string (node-name node) s))

         #'node-children keys))

Figure 32. A Horizontal Graph

In Figure 32., the graph has a horizontal orientation and grows toward the right by default. We can supply the :orientation keyword to control this. Evaluating (test-graph g1 :stream *my-window* :orientation :vertical) results in the following graph:

 

Figure 33. A Vertical Graph

The following example uses format-graph-from-roots to create a graph with multiple parents, that is, a graph in which node D is a child of both nodes B and C. Note that it interprets its first argument as a list of top-level graph nodes, so we have wrapped the root node inside a list.

(defun test-graph (win)

  (window-clear win)

  (format-graph-from-roots '((a (b (d)) (c (d))))

                           #'(lambda (x s) (princ (car x) s))

                           #'cdr

                           :stream win

                           :orientation :vertical

                           :merge-duplicates t

                           :duplicate-key #'car)

  (force-output win))