Re: How to add syntax highlighting inside comments for an existing major mode

[martin rudalics]

> I am trying to customize some syntax highlighting for an existing
> major mode. What I would like to do is to display different type of
> comments with different faces.
>
> In this mode, comments are lines that begins with one or several
> «#». What I would like to display differently those which begin with
> «#####» than those which begin with «####», etc.
>
> I tried the 'font-lock-add-keywords' way, but it doesn't seem to work
> inside comments, with something like that :
>
> (font-lock-add-keywords 'ess-mode
>   '(("^##### .*$" . my-beautiful-face)))
>
> Do you have any idea for a proper way to do such a thing ?

Write your own `font-lock-syntactic-face-function' and do

  (setq font-lock-defaults
        '(...
          (font-lock-syntactic-face-function
           . my-font-lock-syntactic-face-function))))

(defun my-font-lock-syntactic-face-function (state)
  (if (nth 3 state)
      (...)
    ;; Here investigate STATE and decide which face to use.
   ))