+ "Delete the active region.
+If KILLP in not-nil, the active region is killed instead of deleted."
+ (cond
+ (killp
+ ;; Don't allow `kill-region' to change the value of `this-command'.
+ (let (this-command)
+ (kill-region (point) (mark) t)))
+ (delete-selection-save-to-register
+ (set-register delete-selection-save-to-register
+ (funcall region-extract-function t))
+ (setq delsel--replace-text-or-position
+ (cons (current-buffer)
+ (and (consp buffer-undo-list) (car buffer-undo-list)))))
+ (t
+ (funcall region-extract-function 'delete-only))))
+
+(defun delete-selection-repeat-replace-region (arg)
+ "Repeat replacing text of highlighted region with typed text.
+Search for the next stretch of text identical to the region last replaced
+by typing text over it and replaces it with the same stretch of text.
+With ARG, repeat that many times. `C-u' means until end of buffer."
+ (interactive "P")
+ (let ((old-text (and delete-selection-save-to-register
+ (get-register delete-selection-save-to-register)))
+ (count (if (consp arg) (point-max)
+ (prefix-numeric-value current-prefix-arg))))
+ (if (not (and old-text
+ (> (length old-text) 0)
+ (or (stringp delsel--replace-text-or-position)
+ (buffer-live-p (car delsel--replace-text-or-position)))))
+ (message "No known previous replacement")
+ ;; If this is the first use after overwriting regions,
+ ;; find the replacement text by looking at the undo list.
+ (when (consp delsel--replace-text-or-position)
+ (let ((buffer (car delsel--replace-text-or-position))
+ (elt (cdr delsel--replace-text-or-position)))
+ (setq delsel--replace-text-or-position nil)
+ (with-current-buffer buffer
+ (save-restriction
+ (widen)
+ ;; Find the text that replaced the region via the undo list.
+ (let ((ul buffer-undo-list) u s e)
+ (when elt
+ (while (consp ul)
+ (setq u (car ul) ul (cdr ul))
+ (cond
+ ((eq u elt) ;; got it
+ (setq ul nil))
+ ((and (consp u) (integerp (car u)) (integerp (cdr u)))
+ (if (and s (= (cdr u) s))
+ (setq s (car u))
+ (setq s (car u) e (cdr u)))))))
+ (cond ((and s e (<= s e) (= s (mark t)))
+ (setq delsel--replace-text-or-position
+ (filter-buffer-substring s e))
+ (set-text-properties
+ 0 (length delsel--replace-text-or-position)
+ nil delsel--replace-text-or-position))
+ ((and (null s) (eq u elt)) ;; Nothing inserted.
+ (setq delsel--replace-text-or-position ""))
+ (t
+ (message "Cannot locate replacement text"))))))))
+ (while (and (> count 0)
+ delsel--replace-text-or-position
+ (search-forward old-text nil t))
+ (replace-match delsel--replace-text-or-position nil t)
+ (setq count (1- count))))))
+
+(defun delete-selection-helper (type)
+ "Delete selection according to TYPE:
+ `yank'
+ For commands which do a yank; ensures the region about to be
+ deleted isn't immediately yanked back, which would make the
+ command a no-op.
+ `supersede'
+ Delete the active region and ignore the current command,
+ i.e. the command will just delete the region. This is for
+ commands that normally delete small amounts of text, like
+ a single character -- they will instead delete the whole
+ active region.
+ `kill'
+ `kill-region' is used on the selection, rather than
+ `delete-region'. (Text selected with the mouse will
+ typically be yankable anyhow.)
+ FUNCTION
+ For commands which need to dynamically determine this
+ behavior. FUNCTION should take no argument and return a
+ value acceptable as TYPE, or nil. In the latter case,
+ FUNCTION should itself do with the active region whatever is
+ appropriate.
+ Other non-nil values
+ The normal case: delete the active region prior to executing
+ the command which will insert replacement text."
+ (condition-case data
+ (cond ((eq type 'kill) ;Deprecated, backward compatibility.
+ (delete-active-region t)
+ (if (and overwrite-mode
+ (eq this-command 'self-insert-command))
+ (let ((overwrite-mode nil))
+ (self-insert-command
+ (prefix-numeric-value current-prefix-arg))
+ (setq this-command 'ignore))))
+ ((eq type 'yank)
+ ;; Before a yank command, make sure we don't yank the
+ ;; head of the kill-ring that really comes from the
+ ;; currently active region we are going to delete.
+ ;; That would make yank a no-op.
+ (when (and (string= (buffer-substring-no-properties
+ (point) (mark))
+ (car kill-ring))
+ (fboundp 'mouse-region-match)
+ (mouse-region-match))
+ (current-kill 1))
+ (let ((pos (copy-marker (region-beginning))))
+ (delete-active-region)
+ ;; If the region was, say, rectangular, make sure we yank
+ ;; from the top, to "replace".
+ (goto-char pos)))
+ ((eq type 'supersede)
+ (let ((empty-region (= (point) (mark))))
+ (delete-active-region)
+ (unless empty-region
+ (setq this-command 'ignore))))
+ ((functionp type) (delete-selection-helper (funcall type)))
+ (type
+ (delete-active-region)
+ (if (and overwrite-mode
+ (eq this-command 'self-insert-command))
+ (let ((overwrite-mode nil))
+ (self-insert-command
+ (prefix-numeric-value current-prefix-arg))
+ (setq this-command 'ignore)))))
+ ;; If ask-user-about-supersession-threat signals an error,
+ ;; stop safe_run_hooks from clearing out pre-command-hook.
+ (file-supersession (message "%s" (cadr data)) (ding))
+ (text-read-only
+ ;; This signal may come either from `delete-active-region' or
+ ;; `self-insert-command' (when `overwrite-mode' is non-nil).
+ ;; To avoid clearing out `pre-command-hook' we handle this case
+ ;; by issuing a simple message. Note, however, that we do not
+ ;; handle all related problems: When read-only text ends before
+ ;; the end of the region, the latter is not deleted but any
+ ;; subsequent insertion will succeed. We could avoid this case
+ ;; by doing a (setq this-command 'ignore) here. This would,
+ ;; however, still not handle the case where read-only text ends
+ ;; precisely where the region starts: In that case the deletion
+ ;; would succeed but the subsequent insertion would fail with a
+ ;; text-read-only error. To handle that case we would have to
+ ;; investigate text properties at both ends of the region and
+ ;; skip the deletion when inserting text is forbidden there.
+ (message "Text is read-only") (ding))))