Merge branch 'working-on-combining-params' into results

lisp/org-babel.el

@@ -474,6 +474,34 @@ non-nil."
         (dotimes (n size)
           (move-beginning-of-line 1) (insert ": ") (forward-line 1))))))
 
+(defun org-babel-merge-params (&rest plists)
+  "Combine all parameter association lists in PLISTS.  Later
+elements of PLISTS override the values of previous element.  This
+takes into account some special considerations for certain
+parameters when merging lists."
+  (let (params results vars var ref)
+    (mapc (lambda (plist)
+            (mapc (lambda (pair)
+                    (case (car pair)
+                      (:var
+                       ;; we want only one specification per variable
+		       (when (string-match "\\(.+\\)=\\(.+\\)" (cdr pair))
+			 ;; TODO: When is this not true? Can there be whitespace around the '='?
+			 (setq var (match-string 1 (cdr pair))
+			       ref (match-string 2 (cdr pair))
+			       vars (cons (cons var ref) (assq-delete-all var vars)))))
+		      (:results
+		       ;; maintain list of unique :results specifications
+		       (setq results (org-uniquify (append (split-string (cdr pair)) results))))
+                      (t
+		       ;; replace: this covers e.g. :session
+		       (setq params (cons pair (assq-delete-all	(car pair) params))))))
+                  plist))
+          plists)
+    (setq vars (mapcar (lambda (pair) (format "%s=%s" (car pair) (cdr pair))) vars))
+    (while vars (setq params (cons (cons :var (pop vars)) params)))
+    (cons (cons :results (mapconcat 'identity results " ")) params)))
+
 (defun org-babel-clean-text-properties (text)
   "Strip all properties from text return."
   (set-text-properties 0 (length text) nil text) text)