Match regular expression as keyword in define-generic-mode

I'm trying to write a new mode for emacs, using define-generic-mode. I've found a few tutorials which show how you can add keywords (as strings) which will then be highlighted. Is it possible to give define-generic-mode a regular expression so that it can then highlight anything that matches that as a keyword?

I'd like to have a mode in which anything matching a date in the form 15/01/09 is displayed in a different font (preferably underlined, but I'll accept a different colour).

Any ideas?

Robin

From stackoverflow

• for example using font-lock-add-keywords in order to highlight FIXME, TODO and XXX as warning in major modes:

     (dolist (mode '(c-mode
   java-mode
   cperl-mode
   html-mode-hook
   css-mode-hook
   emacs-lisp-mode))
              (font-lock-add-keywords mode 
      '(("\\(XXX\\|FIXME\\|TODO\\)" 
         1 font-lock-warning-face prepend))))
  

• Here's an example of define-generic-mode which sets up the regexp to have all the dates fontified using a custom face with some attributes chosen as examples:

  (make-face 'my-date-face)
  (set-face-attribute 'my-date-face nil :underline t)
  (set-face-attribute 'my-date-face nil :family "times")
  (set-face-attribute 'my-date-face nil :slant 'normal)
  (set-face-attribute 'my-date-face nil :height '340)
  
  (define-generic-mode my-date-mode
    nil
    nil 
    '(("\\([0-9]+/[0-9]+/[0-9]+\\)"
       (1 'my-date-face)))
    nil
    nil)
  

  Oh, and obviously, set the mode by M-x my-date-mode. This can be done automatically via the auto-mode-alist (5th argument to define-generic-mode).

  robintw : Thanks for the reply. I can't seem to get this working though. I've copied in the code, and eval-buffer works fine, but then the right bits don't get underlined. Any idea what the problem is?

  Trey Jackson : (Odd, my first comment was lost). I just edited the code to properly work. I thought I'd tested the previous form, but it fails for some unknown reason. This variant uses a sub expression in the regexp (requiring the `(1 'my-date-face)`). I don't know why the previous didn't work.

  robintw : Thanks - it works fine now. :)

  RamyenHead : can we have this as a minor mode so that we can turn it off and on?

  Trey Jackson : @RamyenHead Check out `define-minor-mode`, similar arguments as `define-generic-mode`.