Footnotes: Activate labels as links

This commit add a new face for footnote labels, and activates footnote
labels for mouse clicks and for `C-c C-o', to jump to the
corresponding reference or definition.

ORGWEBPAGE/Changes.org

@@ -26,9 +26,9 @@ reference is simply the marker in square brackets inside text.
 For example:
 
 #+begin_src org
- The Org homepage[1] now looks a lot better than it used to.
+ The Org homepage[fn:1] now looks a lot better than it used to.
  ...
- [1] The link is: http://orgmode.org
+ [fn:1] The link is: http://orgmode.org
 #+end_src
 
 Org-mode extends the number-based syntax to /named/ footnotes and
@@ -43,15 +43,14 @@ references:
      unique label word or, for simplicity of automatic creation,
      a number. 
      
-- [fn:: This is the inline definition of this footnote] ::
-     A LaTeX-like anonymous footnote where the definition is given
+- [fn:: This is the inline definition of this footnote] :: A
+     LaTeX-like anonymous footnote where the definition is given
      directly at the reference point.
 
-- [fn:name: a definition] ::
-     An inline definition of a footnote, which also specifies a name
-     for the note.  Since Org allows multiple references to the same
-     note, you can then use use `[fn:name]' to create additional
-     references.
+- [fn:name: a definition] :: An inline definition of a footnote,
+     which also specifies a name for the note.  Since Org allows
+     multiple references to the same note, you can then use use
+     `[fn:name]' to create additional references.
 
 Footnote labels can be created automatically, or you create names
 yourself.  This is handled by the variable
@@ -60,19 +59,17 @@ keywords, see the docstring of that variable for details.
 
 The following command handles footnotes:
 
-- C-c C-x f ::
-     The footnote action command.  When the cursor is on a
-     footnote reference, jump to the definition.  When it is at a
-     definition, jump to the (first) reference.  Otherwise,
+- C-c C-x f :: The footnote action command.  When the cursor is
+     on a footnote reference, jump to the definition.  When it is
+     at a definition, jump to the (first) reference.  Otherwise,
      create a new footnote.  Depending on the variable
      `org-footnote-define-inline' (with associated =#+STARTUP=
      options =fninline= and =nofninline=), the definitions will
      be placed locally, or into the nearest outline section with
      the heading `Footnotes'.  If no such section is found after
      the reference point, one will be created at the end of the
-     file.
-     When this command is called with a prefix argument, a menu of
-     additional options is offered:
+     file.  When this command is called with a prefix argument, a
+     menu of additional options is offered:
      - s :: Sort the footnote definitions by reference sequence.
             During editing, Org makes no effort to sort
             footnote definitions into a particular sequence.
@@ -87,11 +84,14 @@ The following command handles footnotes:
             something like `message-send-hook'.
      - d :: Delete the footnote at point, and all references to it.
      
-- C-c C-c ::
-     If the cursor is on a footnote reference, jump to the definition.
-     If it is a the definition, jump back to the reference.  When
-     called with a prefix argument at either location, offer the
-     same menu as `C-u C-c C-x f'.
+- C-c C-c :: If the cursor is on a footnote reference, jump to
+     the definition.  If it is a the definition, jump back to the
+     reference.  When called with a prefix argument at either
+     location, offer the same menu as `C-u C-c C-x f'.
+
+- C-c C-o or mouse-1/2 :: Footnote labels are also links to the
+     corresponding definition/reference, and you can use the
+     usual commands to follow these links.
 
 Org-mode's footnote support is designed so that it should also
 work in buffers that are not in Org-mode, for example in email

doc/org.texi

@@ -1443,6 +1443,12 @@ d   @r{Delete the footnote at point, and all definitions of and references}
 If the cursor is on a footnote reference, jump to the definition.  If it is a
 the definition, jump back to the reference.  When called at a footnote
 location with a prefix argument, offer the same menu as @kbd{C-c C-x f}.
+@kindex C-c C-o
+@kindex mouse-1
+@kindex mouse-2
+@item C-c C-c  @r{or} mouse-1/2
+Footnote labels are also links to the corresponding definition/reference, and
+you can use the usual commands to follow these links.
 @end table
 
 @node Orgstruct mode,  , Footnotes, Document Structure

lisp/ChangeLog

@@ -1,3 +1,12 @@
+2009-01-02  Carsten Dominik  <carsten.dominik@gmail.com>
+
+	* org.el (org-set-font-lock-defaults): Trigger footnote
+	fontification.
+	(org-activate-footnote-links): New function.
+	(org-activate-links): New entry `footnote'.
+
+	* org-faces.el (org-footnote): New face.
+
 2009-01-01  Carsten Dominik  <carsten.dominik@gmail.com>
 
 	* org-macs.el (org-re): Handle the [:word:] class.

lisp/org-faces.el

@@ -239,6 +239,13 @@ column view defines special faces for each outline level.  See the file
   "Face for links."
   :group 'org-faces)
 
+(defface org-footnote
+  '((((class color) (background light)) (:foreground "Purple" :underline t))
+    (((class color) (background dark)) (:foreground "Cyan" :underline t))
+    (t (:underline t)))
+  "Face for links."
+  :group 'org-faces)
+
 (defface org-ellipsis
   '((((class color) (background light)) (:foreground "DarkGoldenrod" :underline t))
     (((class color) (background dark)) (:foreground "LightGoldenrod" :underline t))

lisp/org-footnote.el

@@ -148,6 +148,7 @@ with start and label of the footnote if there is a definition at point."
     (if (not pos)
 	(error "Cannot find definition of footnote %s" label)
       (goto-char pos)
+      (org-show-context 'link-search)
       (message "Edit definition and go back with `C-c &' or, if unique, with `C-c C-c'."))))
 
 (defun org-footnote-goto-next-reference (label)
@@ -166,7 +167,10 @@ with start and label of the footnote if there is a definition at point."
 			 (re-search-forward re nil t))
 		    (and (goto-char (point-min))
 			 (re-search-forward re nil t)))))
-    (if pos (goto-char pos)
+    (if pos
+	(progn
+	  (goto-char pos)
+	  (org-show-context 'link-search))
       (error "Cannot find reference of footnote %s" label))))
 
 (defun org-footnote-normalize-label (label)

lisp/org.el

@@ -888,7 +888,7 @@ adaptive  Use relative path for files in the current directory and sub-
 	  (const noabbrev)
 	  (const adaptive)))
 
-(defcustom org-activate-links '(bracket angle plain radio tag date)
+(defcustom org-activate-links '(bracket angle plain radio tag date footnote)
   "Types of links that should be activated in Org-mode files.
 This is a list of symbols, each leading to the activation of a certain link
 type.  In principle, it does not hurt to turn on most link types - there may
@@ -901,15 +901,18 @@ plain     Plain links in normal text, no whitespace, like http://google.com.
 radio     Text that is matched by a radio target, see manual for details.
 tag       Tag settings in a headline (link to tag search).
 date      Time stamps (link to calendar).
+footnote  Footnote labels.
 
 Changing this variable requires a restart of Emacs to become effective."
   :group 'org-link
-  :type '(set (const :tag "Double bracket links (new style)" bracket)
+  :type '(set :greedy t
+	      (const :tag "Double bracket links (new style)" bracket)
 	      (const :tag "Angular bracket links (old style)" angular)
 	      (const :tag "Plain text links" plain)
 	      (const :tag "Radio target matches" radio)
 	      (const :tag "Tags" tag)
-	      (const :tag "Timestamps" date)))
+	      (const :tag "Timestamps" date)
+	      (const :tag "Footnotes" footnote)))
 
 (defcustom org-make-link-description-function nil
   "Function to use to generate link descriptions from links. If
@@ -3749,6 +3752,22 @@ will be prompted for."
 				   ))
 	t)))
 
+(defun org-activate-footnote-links (limit)
+  "Run through the buffer and add overlays to links."
+  (if (re-search-forward "\\[\\([0-9]+\\]\\|fn:[^ \t\r\n:]+?[]:]\\)" 
+			 limit t)
+      (progn
+	(add-text-properties (match-beginning 0) (match-end 0)
+			     (list 'mouse-face 'highlight
+				   'rear-nonsticky org-nonsticky-props
+				   'keymap org-mouse-map
+				   'help-echo
+				   (if (= (point-at-bol) (match-beginning 0))
+				       "Footnote definition"
+				     "Footnote reference")
+				   ))
+	t)))
+
 (defun org-activate-bracket-links (limit)
   "Run through the buffer and add overlays to bracketed links."
   (if (re-search-forward org-bracket-link-regexp limit t)
@@ -4003,6 +4022,8 @@ between words."
 	   (if (memq 'bracket lk) '(org-activate-bracket-links (0 'org-link t)))
 	   (if (memq 'radio lk) '(org-activate-target-links (0 'org-link t)))
 	   (if (memq 'date lk) '(org-activate-dates (0 'org-date t)))
+	   (if (memq 'footnote lk) '(org-activate-footnote-links
+				     (0 'org-footnote t)))
 	   '("^&?%%(.*\\|<%%([^>\n]*?>" (0 'org-sexp-date t))
 	   '(org-hide-wide-columns (0 nil append))
 	   ;; TODO lines
@@ -6913,8 +6934,11 @@ application the system uses for this file type."
   (move-marker org-open-link-marker (point))
   (setq org-window-config-before-follow-link (current-window-configuration))
   (org-remove-occur-highlights nil nil t)
-  (if (org-at-timestamp-p t)
-      (org-follow-timestamp-link)
+  (cond
+   ((org-at-timestamp-p t) (org-follow-timestamp-link))
+   ((or (org-footnote-at-reference-p) (org-footnote-at-definition-p))
+    (org-footnote-action))
+   (t 
     (let (type path link line search (pos (point)))
       (catch 'match
 	(save-excursion
@@ -7060,7 +7084,7 @@ application the system uses for this file type."
 	    (error "Abort"))))
 
        (t
-	(browse-url-at-point)))))
+	(browse-url-at-point))))))
   (move-marker org-open-link-marker nil)
   (run-hook-with-args 'org-follow-link-hook))