Telling Emacs to mark \iffalse...\fi blocks?

Question

Do you know a simple way to tell GNU Emacs to recognize LaTeX \iffalse ... \fi blocks and to display them in a special way, e.g., using a lighter font, or using font-lock-comment-face. Is there a LaTeX style package that already knows how to do this?

I understand that correctly recognizing valid \iffalse's and their matching \fi's in arbitrary LaTeX source file is a non-trivial problem, but I am happy with an approximate solution that works in most easy cases, e.g., that assumes no nesting of \if\fi's and requires these commands to appear alone on their source line.

I've little idea how to do this, but I believe AUCTeX would could/would be useful here---is its use allowed, or should it stick to normal tex-mode? — Sean Allred, Jul 30 '13 at 17:08

score 7 · Answer 1 · answered Mar 22 '14 at 17:36

This solution does not require AUCTeX to the best of my knowledge.

Add the following to your .emacs:

(add-hook 'TeX-mode-hook
  (lambda ()
    (font-lock-add-keywords nil '(
      ("\\\\iffalse\\(\\(.\\|\n\\)*?\\)\\\\fi" 1 font-lock-comment-face)))))

result

Telling Emacs to mark \iffalse...\fi blocks?

1 Answers1