changed Scheme code to Elisp code

headers/headers.org

@@ -30,48 +30,57 @@
 
 # ### CODE #####################################################################
 
-#+NAME: process-tree
-#+BEGIN_SRC scheme :noweb yes :exports none :eval yes :cache yes
-  ;; Original commented source code hosted on Phundrak Labs:
-  ;; https://labs.phundrak.fr/phundrak/features-tree
+#+NAME: tree-dot
+#+BEGIN_SRC emacs-lisp :noweb yes :exports none :eval yes :cache yes
+  (defun declare-node (node-text node-generation)
+    "Declares a node in the graphviz source code. The node’s identifier will be
+  ~node-generation~, and it will bear the label ~node-text~."
+    (concat (number-to-string node-generation)
+            "[label=\""
+            node-text
+            "\"];"))
 
-  (define (atom? elem)
-    (not (pair? elem)))
+  (defun make-link (previous-node current-node)
+    "This creates a link in the graphviz source code between the two nodes
+  bearing ~previous-node~ and ~current-node~ respectively as their node
+  identifier."
+    (concat (number-to-string previous-node) " -- "
+            (number-to-string current-node) ";"))
 
-  (define (declare-node node-text node-generation)
-    (string-append ;; "node"
-                   (number->string node-generation)
-                   "[label=\""
-                   node-text
-                   "\"];"))
+  (defun tree-to-dot-helper (tree current-generation previous-generation)
+    "Helper to ~tree-to-dot~ that translates an Elisp tree with any number of
+  children per node to a corresponding graphviz file that can be executed from
+  dot.
+  Arguments:
+  - tree :: tree-to-convert
+  - current-generation :: Generation number, incremented when changing from a node
+       to another node from the same generation, multiplied by 10 when going from
+       a node to one of its children.
+  - previous-generation :: generation number from previous named node"
+    (cond
+     ((null tree) "")
+     ((atom (car tree)) ;; '("text" () () ())
+      (concat (declare-node (car tree) current-generation)
+              (make-link previous-generation current-generation)
+              (tree-to-dot-helper (cdr tree)
+                                  (+ 1 (* 10 current-generation))
+                                  current-generation)))
+     ((listp (car tree)) ;; '(() () ())
+      (concat (tree-to-dot-helper (car tree) ;; child of current node
+                                  current-generation
+                                  previous-generation)
+              (tree-to-dot-helper (cdr tree)
+                                  (+ 1 current-generation)
+                                  previous-generation)))))
 
-  (define (make-link previous-node current-node)
-    (string-append (number->string previous-node) " -- "
-                   (number->string current-node) ";"))
-
-  (define (tree-to-dot-helper tree current-generation previous-generation)
-    (cond ((null? tree) "")
-          ((atom? (car tree))
-           (string-append (declare-node (car tree) current-generation)
-                          (make-link previous-generation current-generation)
-                          (tree-to-dot-helper (cdr tree)
-                                              (+ 1 (* 10 current-generation))
-                                              current-generation)))
-          ((list? (car tree))
-           (string-append (tree-to-dot-helper (car tree)
-                                              current-generation
-                                              previous-generation)
-                          (tree-to-dot-helper (cdr tree)
-                                              (+ 1 current-generation)
-                                              previous-generation)))))
-
-  (define (tree-to-dot tree)
-    (if (null? tree) ""
-        (string-append
-         "graph{node[shape=plaintext];graph[bgcolor=\"transparent\"];"
-         (declare-node (car tree) 0)
-         (tree-to-dot-helper (cdr tree) 1 0)
-         "}")))
+  (defun tree-to-dot (tree)
+    "Returns a graphviz’s dot compatible string representing an Elisp tree"
+    (if (null tree) ""
+      (concat
+       "graph{node[shape=plaintext];graph[bgcolor=\"transparent\"];"
+       (declare-node (car tree) 0)
+       (tree-to-dot-helper (cdr tree) 1 0)
+       "}")))
 #+END_SRC
 
 # ### MACROS ###################################################################