I have a log file that has a lot of tagging information, i.e, "ERROR", "WARNING", "*". I want to show the log info with different color/fonts based on the tagging info. How can I do that?
Do I have to come up with my own major/minor modes? Is there some elisp code that I can reuse?
You can do this interactively with:
M-s h r regexp <RET> FACE <RET>
or
C-x w h regexp <RET> FACE <RET>
see the documentation for Interactive Highlighting. Note: The second key binding is only available after you've turned on Hi-Lock mode via M-x global-hi-lock-mode.
If you want to set up a minor mode to do this on a regular basis, I'd check out fixme-mode and modify things from there.
It might be useful to read the Faces portion of the manual to understand what is going on.
You can use a similar function in hooks for modes you care:
(defun add-watchwords ()
(font-lock-add-keywords
nil '(("\\<\\(FIX\\|TODO\\|FIXME\\|HACK\\|REFACTOR\\):"
1 font-lock-warning-face t))))
I use this for coding modes obviously, so you should adjust the items you want highlighted.
Generic Mode was designed to ease the creation of simple custom modes for things like this.