Implement link translation.

This patch implements the possibility to translate links.
It can be useful if use both planner and Org-mode, if you sometimes
copy text from one side to the other and you do not want to worry
about link syntax.  This patch allows links created with planner to
function correctly in Org-mode.  I would probably be simple to
implement the reverse conversion in planner as well.

This patch is a first shot at this functionality and very likely can
be improved.

doc/ChangeLog

@@ -2,6 +2,8 @@
 
 	* org.texi (External links): Document that bbdb links can use a
 	regular expression.
+	(External links): Document that elisp links can contain
+	interactive commands.
 
 2008-11-10  Carsten Dominik  <carsten.dominik@gmail.com>
 

doc/org.texi

@@ -2526,7 +2526,8 @@ gnus:group#id                             @r{Gnus article link}
 bbdb:R.*Stallman                          @r{BBDB link (with regexp)}
 irc:/irc.com/#emacs/bob                   @r{IRC link}
 shell:ls *.org                            @r{A shell command}
-elisp:(find-file-other-frame "Elisp.org") @r{An elisp form to evaluate}
+elisp:org-agenda                          @r{Interactive elisp command}
+elisp:(find-file-other-frame "Elisp.org") @r{Elisp form to evaluate}
 @end example
 
 A link should be enclosed in double brackets and may contain a

lisp/ChangeLog

@@ -1,5 +1,12 @@
 2008-11-14  Carsten Dominik  <carsten.dominik@gmail.com>
 
+	* org.el (org-link-translation-function): New option.
+	(org-open-at-point): Call `org-link-translation-function' if
+	non-nil.
+	(org-translate-link): New function.
+	(org-translate-link-from-planner): New function.
+	(org-open-at-point): Allow interactive commands in elisp links.
+
 	* org-exp.el (org-icalendar-cleanup-string): Restore the old
 	iCalendar quoting.  The new one seems to caus problems with
 	applications.

lisp/org-exp.el

@@ -1885,7 +1885,8 @@ When it is nil, all comments will be removed."
       (goto-char (1- (match-end 0)))
       (org-if-unprotected
        (let* ((xx (save-match-data
-		    (org-link-expand-abbrev (match-string 1))))
+		    (org-translate-link
+		     (org-link-expand-abbrev (match-string 1)))))
 	      (s (concat
 		  "[[" xx "]"
 		  (if (match-end 3)

lisp/org.el

@@ -981,6 +981,20 @@ more efficient."
   :tag "Org Follow Link"
   :group 'org-link)
 
+(defcustom org-link-translation-function nil
+  "Function to translate links with different syntax to Org syntax.
+This can be used to translate links created for example by the Planner
+or emacs-wiki packages to Org syntax.
+The function must accept two parameters, a TYPE containing the link
+protocol name like \"rmail\" or \"gnus\" as a string, and the linked path,
+which is everything after the link protocol.  It should return a cons
+with possibly modifed values of type and path.
+Org contains a function for this, so if you set this variable to
+`org-translate-link-from-planner', you should be able follow many
+links created by planner."
+  :group 'org-link-follow
+  :type 'function)
+
 (defcustom org-follow-link-hook nil
   "Hook that is run after a link has been followed."
   :group 'org-link-follow
@@ -3399,6 +3413,8 @@ The following commands are available:
    "Matches a link with spaces, optional angular brackets around it.")
 (defvar org-link-re-with-space2 nil
    "Matches a link with spaces, optional angular brackets around it.")
+(defvar org-link-re-with-space3 nil
+   "Matches a link with spaces, only for internal part in bracket links.")
 (defvar org-angle-link-re nil
    "Matches link with angular brackets, spaces are allowed.")
 (defvar org-plain-link-re nil
@@ -3434,6 +3450,11 @@ This should be called after the variable `org-link-types' has changed."
 	 "\\([^" org-non-link-chars " ]"
 	 "[^\t\n\r]*"
 	 "[^" org-non-link-chars " ]\\)>?")
+	org-link-re-with-space3
+	(concat
+	 "<?\\(" (mapconcat 'identity org-link-types "\\|") "\\):"
+	 "\\([^" org-non-link-chars " ]"
+	 "[^\t\n\r]*\\)")
 	org-angle-link-re
 	(concat
 	 "<\\(" (mapconcat 'identity org-link-types "\\|") "\\):"
@@ -6606,6 +6627,39 @@ If the link is in hidden text, expose it."
       (setq org-link-search-failed t)
       (error "No further link found"))))
 
+(defun org-translate-link (s)
+  "Translate a link string if a translation function has been defined."
+  (if (and org-link-translation-function
+	   (fboundp org-link-translation-function)
+	   (string-match "\\([a-zA-Z0-9]+\\):\\(.*\\)"))
+      (progn
+	(setq s (funcall org-link-translation-function
+			 (match-string 1) (match-string 2)))
+	(concat (car s) ":" (cdr s)))
+    s))
+
+(defun org-translate-link-from-planner (type path)
+  "Translate a link from Emacs Planner syntax so that Org can follow it.
+This is still an experimental function, your mileage may vary."
+ (cond
+  ((member type '("http" "https" "news" "ftp"))
+   ;; standard Internet links are the same.
+   nil)
+  ((and (equal type "irc") (string-match "^//" path))
+   ;; Planner has two / at the beginning of an irc link, we have 1.
+   ;; We should have zero, actually....
+   (setq path (substring path 1)))
+  ((and (equal type "lisp") (string-match "^/" path))
+   ;; Planner has a slash, we do not.
+   (setq type elisp path (substring path 1)))
+  ((string-match "^//\\(.?*\\)/\\(<.*>\\)$" path)
+   ;; A typical message link.  Planner has the id after the fina slash,
+   ;; we separate it with a hash mark
+   (setq path (concat (match-string 1 path) "#"
+		      (org-remove-angle-brackets (match-string 2 path)))))
+  )
+ (cons type path))
+
 (defun org-find-file-at-mouse (ev)
   "Open file link or URL at mouse."
   (interactive "e")
@@ -6673,7 +6727,7 @@ application the system uses for this file type."
 	     ((or (file-name-absolute-p link)
 		  (string-match "^\\.\\.?/" link))
 	      (setq type "file" path link))
-	     ((string-match org-link-re-with-space2 link)
+	     ((string-match org-link-re-with-space3 link)
 	      (setq type (match-string 1 link) path (match-string 2 link)))
 	     (t (setq type "thisfile" path link)))
 	    (throw 'match t)))
@@ -6708,6 +6762,11 @@ application the system uses for this file type."
       ;; Remove any trailing spaces in path
       (if (string-match " +\\'" path)
 	  (setq path (replace-match "" t t path)))
+      (if (and org-link-translation-function
+	       (fboundp org-link-translation-function))
+	  ;; Check if we need to translate the link
+	  (let ((tmp (funcall org-link-translation-function type path)))
+	    (setq type (car tmp) path (cdr tmp))))
 
       (cond
 
@@ -6792,7 +6851,10 @@ application the system uses for this file type."
 			   (format "Execute \"%s\" as elisp? "
 				   (org-add-props cmd nil
 				     'face 'org-warning))))
-	      (message "%s => %s" cmd (eval (read cmd)))
+	      (message "%s => %s" cmd 
+		       (if (equal (string-to-char cmd) ?\()
+			   (call-interactively (read cmd))
+			 (eval (read cmd))))
 	    (error "Abort"))))
 
        (t