New version of message-tab

[Kai Grossjohann <grossjohann@charly.informatik.uni-dortmund.de>]

Hi all,

there is message-tab which I like a lot, but I also think it could be
more general.  So I tried to hack up something useful.

You can set a variable message-x-body-function to a function that TAB
should execute when point is in the body of a message.

You can set an alist message-x-completion-alist which tells for each
header which function should be invoked when TAB is typed.  As I use
bbdb, the default says to invoke bbdb-complete-name in To and Cc
headers.  Also, message-expand-group is invoked in a Newsgroups
header.

Be careful: the header values are NOT strings, comparison is done
using `equal'.  Therefore, "to\\|cc" refers to a very strange header,
not to both the To and Cc headers!

How do you like this?  Could this be added to Gnus?  Or is it in Red
Gnus already, in which case I apologize.

This is v\bve\ber\bry\by ugly code; I don't know why it works, either ;-)

regards,
kai
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;; message-x.el -- customizable completion in message headers
;; Kai Grossjohann <grossjohann@ls6.informatik.uni-dortmund.de>
;;  9 Aug 96

(require 'message)

(defvar message-x-body-function 'indent-relative
  "message-x-tab executes this if point is in the body of a message.")

(defvar message-x-completion-alist
  '(("to" . bbdb-complete-name)
    ("cc" . bbdb-complete-name)
    ("newsgroups" . message-expand-group))
  "Table telling which completion function message-x-tab should invoke.
Lookup in the table is done with `equal' comparison of the header.")

(defun message-x-in-header-p ()
  "Returns t iff point is in the header section."
  (save-excursion
    (let ((p (point)))
      (beginning-of-buffer)
      (and (re-search-forward (concat "^"
				      (regexp-quote mail-header-separator)
				      "$"))
	   (progn (beginning-of-line) t)
	   (< p (point))))))
	  

(defun message-x-which-header ()
  "Returns the header we're currently in.  Returns nil if not in a header.
Example: returns \"to\" if we're in the \"to\" header right now."
  (and (message-x-in-header-p)
       (save-excursion
	 (beginning-of-line)
	 (while (looking-at "^[ \t]+") (forward-line -1))
	 (looking-at "\\([^:]+\\):")
	 (downcase (buffer-substring-no-properties (match-beginning 1)
						   (match-end 1))))))

(defun message-x-tab ()
  "Does completion based on header currently in or executes a default
function in the body."
  (interactive)
  (let ((header (assoc (message-x-which-header)
		       message-x-completion-alist)))
    (funcall
     (if header (cdr header) message-x-body-function))))

(define-key message-mode-map "\t" 'message-x-tab)

(provide 'message-x)
;; message-x.el ends here