font-lock keywords that change depending on language

font-lock keywords that change depending on language

[Joe Corneli]

I would like to do something like this

(defvar todl-font-lock-keywords-1
  (list '((concat "^" todl-top-level-node-phrase ":")
          . font-lock-builtin-face))
  "Minimal highlighting expressions for TODL mode.")

where todl-top-level-node-phrase is "Top-level node" when the user
is working in English, but "Oberster Stufen Knoten" when the user is
working in German.  

Unfortunately, the above does not seem to work at all.  Is this to
be expected (I'm doing something wrong)? - or is it a bug?

Re: font-lock keywords that change depending on language

[Oliver Scholz]

Joe Corneli <jcorneli@math.utexas.edu> wrote in message news:<mailman.1103.1082676809.1061.help-gnu-emacs@gnu.org>...
> I would like to do something like this
> 
> (defvar todl-font-lock-keywords-1
>   (list '((concat "^" todl-top-level-node-phrase ":")
>           . font-lock-builtin-face))
>   "Minimal highlighting expressions for TODL mode.")
> 
> where todl-top-level-node-phrase is "Top-level node" when the user
> is working in English, but "Oberster Stufen Knoten" when the user is
> working in German.  
> 
> Unfortunately, the above does not seem to work at all.  Is this to
> be expected (I'm doing something wrong)? - or is it a bug?

It is to be expected, your expression above gets evaluated (usually)
just once, at load time.

If you want font-lock to constantly check for a variable you could use
a function as MATCHER in `font-lock-keywords'. For example:

(defconst test-font-lock-keywords
  '((test-font-lock-function
     (0 font-lock-warning-face))))

(defvar test-buffer-language
  'english)

(defconst test-english-regexp
  "top level node")

(defconst test-german-regexp
  "oberster Knotenpunkt")

(defun test-font-lock-function (limit)
  ;; We don't need to do anything else here, because
  ;; `re-search-forward' sets the match data as we need it.
  (or (and (eq test-buffer-language
	       'english)
	   (re-search-forward test-english-regexp
			      limit t))
      (and (eq test-buffer-language
	       'german)
	   (re-search-forward test-german-regexp
			      limit t))))

;; Testing

;; (define-derived-mode test-mode text-mode "test "
;;   ""
;;   (setq font-lock-defaults
;; 	(list test-font-lock-keywords)))

Re: font-lock keywords that change depending on language

[Joe Corneli]

  If you want font-lock to constantly check for a variable you could
  use a function as MATCHER in `font-lock-keywords'.

Heh.  Thanks.  I seem to have gotten it going now, modulo a few
details that seem unique to my code.  The only difficulty I ran into
adapting your test example was that I forgot to switch the
appearances of `eq' to `equal' to do comparisons between strings.