Function: font-lock-remove-keywords

font-lock-remove-keywords is a byte-compiled function defined in font-lock.el.gz.

Signature

(font-lock-remove-keywords MODE KEYWORDS)

Documentation

Remove highlighting KEYWORDS for MODE.

MODE should be a symbol, the major mode command name, such as c-mode or nil. If nil, highlighting keywords are removed for the current buffer.

For a description of KEYWORDS, see font-lock-add-keywords.

To make the removal apply to modes derived from MODE as well, pass nil for MODE and add the call to MODE-hook. This may fail for some derived modes if some involved major mode does not follow the standard conventions. File a bug report if this happens, so the major mode can be corrected.

Probably introduced at or before Emacs version 21.1.

Source Code

;; Defined in /usr/src/emacs/lisp/font-lock.el.gz
;; Written by Anders Lindgren
;;
;; Case study:
;; (I)  The keywords are removed from a major mode.
;;      In this case the keyword could be local (i.e. added earlier by
;;      `font-lock-add-keywords'), global, or both.
;;
;;      (a) In the local case we remove the keywords from the variable
;;          `font-lock-keywords-alist'.
;;
;;      (b) The actual global keywords are not known at this time.
;;          All keywords are added to `font-lock-removed-keywords-alist',
;;          when font-lock is enabled those keywords are removed.
;;
;;      Note that added keywords are taken out of the list of removed
;;      keywords.  This ensure correct operation when the same keyword
;;      is added and removed several times.
;;
;; (II) The keywords are removed from the current buffer.
(defun font-lock-remove-keywords (mode keywords)
  "Remove highlighting KEYWORDS for MODE.

MODE should be a symbol, the major mode command name, such as
`c-mode' or nil.  If nil, highlighting keywords are removed for
the current buffer.

For a description of KEYWORDS, see `font-lock-add-keywords'.

To make the removal apply to modes derived from MODE as well,
pass nil for MODE and add the call to MODE-hook.  This may fail
for some derived modes if some involved major mode does not
follow the standard conventions.  File a bug report if this
happens, so the major mode can be corrected."
  (cond (mode
	 ;; Remove one keyword at the time.
	 (dolist (keyword keywords)
	   (let ((top-cell (assq mode font-lock-keywords-alist)))
	     ;; If MODE is non-nil, remove the KEYWORD from
	     ;; `font-lock-keywords-alist'.
	     (when top-cell
	       (dolist (keyword-list-how-pair (cdr top-cell))
                 ;; `keyword-list-how-pair' is a cons with a list of
		 ;; keywords in the car top-cell and the original how
		 ;; argument in the cdr top-cell.
		 (setcar keyword-list-how-pair
			 (delete keyword (car keyword-list-how-pair))))
	       ;; Remove keyword list/how pair when the keyword list
	       ;; is empty and how doesn't specify `set'.  (If it
	       ;; should be deleted then previously deleted keywords
	       ;; would appear again.)
	       (let ((cell top-cell))
		 (while (cdr cell)
		   (if (and (null (car (car (cdr cell))))
			    (not (eq (cdr (car (cdr cell))) 'set)))
		       (setcdr cell (cdr (cdr cell)))
		     (setq cell (cdr cell)))))
	       ;; Final cleanup, remove major mode cell if last keyword
	       ;; was deleted.
	       (if (null (cdr top-cell))
		   (setq font-lock-keywords-alist
			 (delq top-cell font-lock-keywords-alist))))
	     ;; Remember the keyword in case it is not local.
	     (let ((cell (assq mode font-lock-removed-keywords-alist)))
	       (if cell
		   (unless (member keyword (cdr cell))
		     (nconc cell (list keyword)))
		 (push (cons mode (list keyword))
		       font-lock-removed-keywords-alist))))))
	(t
	 ;; Otherwise remove it immediately.
	 (font-lock-set-defaults)
	 (let ((was-compiled (eq (car font-lock-keywords) t)))
	   ;; Bring back the user-level (uncompiled) keywords.
	   (if was-compiled
	       (setq font-lock-keywords (cadr font-lock-keywords)))

	   ;; Edit them.
	   (setq font-lock-keywords (copy-sequence font-lock-keywords))
	   (dolist (keyword keywords)
	     (setq font-lock-keywords
		   (delete keyword font-lock-keywords)))

	   ;; If the keywords were compiled before, compile them again.
	   (if was-compiled
	       (setq font-lock-keywords
                     (font-lock-compile-keywords font-lock-keywords)))))))