swap-marks.el

swap-marks.el

(defun my-dired--first-char-or-ask ()
  (if (member (char-after (line-beginning-position)) `(?\s ,dired-marker-char))
      (read-char "Which mark are you targeting? ")
    (char-after (line-beginning-position))))

(defun my-dired-swap-marks-ask ()
  (interactive)
  (let ((mark (my-dired--first-char-or-ask)))
    (my-dired-swap-marks (string mark))))


(defun my-dired-swap-marks (mark)
  (save-excursion
    (let ((inhibit-read-only t)
          (beginning (dired-mark--region-beginning))
          (end (dired-mark--region-end))
          (active-marker (string dired-marker-char)))
      (goto-char beginning)
      (while (< (point) end)
	(beginning-of-line)
	(cond ((looking-at active-marker)
	       (replace-match mark nil nil nil nil))
	      ((looking-at mark)
	       (replace-match active-marker nil nil nil nil)))
	(forward-line 1)))))