Introduce compatibility code for looking-back

lisp/ChangeLog

@@ -1,5 +1,15 @@
 2009-11-23  Carsten Dominik  <carsten.dominik@gmail.com>
 
+	* org-mouse.el (org-mouse-end-headline, org-mouse-insert-item)
+	(org-mouse-context-menu): Use `org-looking-back'.
+
+	* org.el (org-cycle-level): Use `org-looking-back'.
+
+	* org-list.el (org-cycle-item-indentation): Use
+	`org-looking-back'.
+
+	* org-compat.el (org-looking-back): New function.
+
 	* org.el (org-insert-heading): Catch before-first-headline when
 	inserting a headline.
 

lisp/org-compat.el

@@ -362,6 +362,40 @@ TIME defaults to the current time."
       (time-to-seconds (or time (current-time)))
     (float-time time)))
 
+; XEmacs does not have `looking-back'.
+(if (fboundp 'looking-back)
+    (defalias 'org-looking-back 'looking-back)
+  (defun org-looking-back (regexp &optional limit greedy)
+    "Return non-nil if text before point matches regular expression REGEXP.
+Like `looking-at' except matches before point, and is slower.
+LIMIT if non-nil speeds up the search by specifying a minimum
+starting position, to avoid checking matches that would start
+before LIMIT.
+
+If GREEDY is non-nil, extend the match backwards as far as
+possible, stopping when a single additional previous character
+cannot be part of a match for REGEXP.  When the match is
+extended, its starting position is allowed to occur before
+LIMIT."
+    (let ((start (point))
+	  (pos
+	   (save-excursion
+	     (and (re-search-backward (concat "\\(?:" regexp "\\)\\=") limit t)
+		  (point)))))
+      (if (and greedy pos)
+	  (save-restriction
+	    (narrow-to-region (point-min) start)
+	    (while (and (> pos (point-min))
+			(save-excursion
+			  (goto-char pos)
+			  (backward-char 1)
+			  (looking-at (concat "\\(?:"  regexp "\\)\\'"))))
+	      (setq pos (1- pos)))
+	    (save-excursion
+	      (goto-char pos)
+	      (looking-at (concat "\\(?:"  regexp "\\)\\'")))))
+      (not (null pos)))))
+
 (provide 'org-compat)
 
 ;; arch-tag: a0a0579f-e68c-4bdf-9e55-93768b846bbe

lisp/org-list.el

@@ -1049,7 +1049,7 @@ Assumes cursor in item line."
 	(org-adapt-indentation nil))
     (cond
      ((and (looking-at "[ \t]*$")
-	   (looking-back "^\\([ \t]*\\)\\([-+*]\\|[0-9]+[).]\\)[ \t]+"))
+	   (org-looking-back "^\\([ \t]*\\)\\([-+*]\\|[0-9]+[).]\\)[ \t]+"))
       (setq this-command 'org-cycle-item-indentation)
       (if (eq last-command 'org-cycle-item-indentation)
 	  (condition-case nil

lisp/org-mouse.el

@@ -189,7 +189,7 @@ Changing this variable requires a restart of Emacs to get activated."
   (interactive)
   (end-of-line)
   (skip-chars-backward "\t ")
-  (when (looking-back ":[A-Za-z]+:")
+  (when (org-looking-back ":[A-Za-z]+:")
     (skip-chars-backward ":A-Za-z")
     (skip-chars-backward "\t ")))
 
@@ -607,7 +607,7 @@ SCHEDULED: or DEADLINE: or ANYTHINGLIKETHIS:"
     (:end				; insert text here
      (skip-chars-backward " \t")
      (kill-region (point) (point-at-eol))
-     (unless (looking-back org-mouse-punctuation)
+     (unless (org-looking-back org-mouse-punctuation)
        (insert (concat org-mouse-punctuation " ")))))
 
   (insert text)
@@ -674,7 +674,7 @@ SCHEDULED: or DEADLINE: or ANYTHINGLIKETHIS:"
 				      'org-mode-restart))))
    ((or (eolp)
 	(and (looking-at "\\(  \\|\t\\)\\(+:[0-9a-zA-Z_:]+\\)?\\(  \\|\t\\)+$")
-	     (looking-back "  \\|\t")))
+	     (org-looking-back "  \\|\t")))
     (org-mouse-popup-global-menu))
    ((get-context :checkbox)
     (popup-menu

lisp/org.el

@@ -6285,7 +6285,7 @@ in the region."
 (defun org-cycle-level ()
   (let ((org-adapt-indentation nil))
     (when (and (looking-at "[ \t]*$")
-	       (looking-back
+	       (org-looking-back
 		(concat "^\\(\\*+\\)[ \t]+\\(" org-todo-regexp "\\)?[ \t]*")))
       (setq this-command 'org-cycle-level)
       (if (eq last-command 'org-cycle-level)