Function: ansi-color-apply-sequence

ansi-color-apply-sequence is a byte-compiled function defined in ansi-color.el.gz.

Signature

(ansi-color-apply-sequence ESCAPE-SEQUENCE CODES)

Documentation

Apply ESCAPE-SEQUENCE to CODES and return the new list of codes.

ESCAPE-SEQUENCE is an escape sequence parsed by ansi-color-parse-sequence.

For each new code, the following happens: if it is 1-7, add it to the list of codes; if it is 21-25 or 27, delete appropriate parameters from the list of codes; if it is 30-37 (or 90-97) resp. 39, the foreground color code is replaced or added resp. deleted; if it is 40-47 (or 100-107) resp. 49, the background color code is replaced or added resp. deleted; any other code is discarded together with the old codes. Finally, the so changed list of codes is returned.

Source Code

;; Defined in /usr/src/emacs/lisp/ansi-color.el.gz
(defun ansi-color-apply-sequence (escape-sequence codes)
  "Apply ESCAPE-SEQUENCE to CODES and return the new list of codes.

ESCAPE-SEQUENCE is an escape sequence parsed by
`ansi-color-parse-sequence'.

For each new code, the following happens: if it is 1-7, add it to
the list of codes; if it is 21-25 or 27, delete appropriate
parameters from the list of codes; if it is 30-37 (or 90-97) resp. 39,
the foreground color code is replaced or added resp. deleted; if it
is 40-47 (or 100-107) resp. 49, the background color code is replaced
or added resp. deleted; any other code is discarded together with the
old codes.  Finally, the so changed list of codes is returned."
  (let ((new-codes (ansi-color-parse-sequence escape-sequence)))
    (while new-codes
      (let* ((new (pop new-codes))
	     (q (/ new 10)))
	(setq codes
	      (pcase q
		(0 (unless (memq new '(0 8 9))
		     (cons new (remq new codes))))
		(2 (unless (memq new '(20 26 28 29))
		     ;; The standard says `21 doubly underlined' while
                     ;; https://en.wikipedia.org/wiki/ANSI_escape_code claims
		     ;; `21 Bright/Bold: off or Underline: Double'.
		     (remq (- new 20) (pcase new
					(22 (remq 1 codes))
					(25 (remq 6 codes))
					(_ codes)))))
		((or 3 4 9 10) (let ((r (mod new 10)))
			    (unless (= r 8)
			      (let (beg)
				(while (and codes (/= q (/ (car codes) 10)))
				  (push (pop codes) beg))
				(setq codes (nconc (nreverse beg) (cdr codes)))
				(if (= r 9)
				    codes
				  (cons new codes))))))
		(_ nil)))))
    codes))