;; non-nil
;; The normal case: delete the active region prior to executing
;; the command which will insert replacement text.
+;; hooks
+;; For commands which need to dynamically determine this behaviour.
+;; Each hook should return one of the above values or nil.
;;; Code:
(transient-mark-mode t)))
(defun delete-active-region (&optional killp)
+ "Delete the active region.
+If KILLP in not-nil, the active region is killed instead of deleted."
(if killp
(kill-region (point) (mark))
(delete-region (point) (mark)))
t)
+(defun delete-selection-helper (type)
+ "Deletes selection according to TYPE:
+ 'yank
+ For commands which do a yank; ensures the region about to be
+ deleted isn't yanked.
+ 'supersede
+ Delete the active region and ignore the current command,
+ i.e. the command will just delete the region.
+ 'kill
+ `kill-region' is used on the selection, rather than
+ `delete-region'. (Text selected with the mouse will typically
+ be yankable anyhow.)
+ non-nil
+ The normal case: delete the active region prior to executing
+ the command which will insert replacement text.
+ hooks
+ For commands which need to dynamically determine this behaviour.
+ Each hook should return one of the above values or nil."
+ (condition-case data
+ (cond ((eq type 'kill)
+ (delete-active-region t))
+ ((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))
+ (delete-active-region))
+ ((eq type 'supersede)
+ (let ((empty-region (= (point) (mark))))
+ (delete-active-region)
+ (unless empty-region
+ (setq this-command 'ignore))))
+ ((and (symbolp type) (not (booleanp type)))
+ (delete-selection-helper
+ (run-hook-with-args-until-success 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))))
+
(defun delete-selection-pre-hook ()
+ "Normal hook run before commands that delete selections are executed.
+Commands which will delete the selection need a 'delete-selection
+property on their symbols; commands which insert text but don't
+have this property won't delete the selection.
+
+See `delete-selection-helper'.
+"
(when (and delete-selection-mode transient-mark-mode mark-active
(not buffer-read-only))
(let ((type (and (symbolp this-command)
(get this-command 'delete-selection))))
- (condition-case data
- (cond ((eq type 'kill)
- (delete-active-region t))
- ((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))
- (delete-active-region))
- ((eq type 'supersede)
- (let ((empty-region (= (point) (mark))))
- (delete-active-region)
- (unless empty-region
- (setq this-command 'ignore))))
- (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))))))
-
-(put 'self-insert-command 'delete-selection t)
-(put 'self-insert-iso 'delete-selection t)
+ (delete-selection-helper type))))
+
+(defun delete-selection-self-insert-function ()
+ t)
+
+(defvar delete-selection-self-insert-hooks
+ '(delete-selection-self-insert-function)
+ "Abnormal hook run before commands that insert characters.
+This hook should return a TYPE that `delete-selection-helper' understands.")
+
+(put 'self-insert-command 'delete-selection 'delete-selection-self-insert-hooks)
+(put 'self-insert-iso 'delete-selection 'delete-selection-self-insert-hooks)
(put 'yank 'delete-selection 'yank)
(put 'clipboard-yank 'delete-selection 'yank)