;;; delsel.el --- delete selection if you insert
-;; Copyright (C) 1992, 1997-1998, 2001-2012 Free Software Foundation, Inc.
+;; Copyright (C) 1992, 1997-1998, 2001-2013 Free Software Foundation,
+;; Inc.
;; Author: Matthieu Devin <devin@lucid.com>
;; Maintainer: FSF
;; `kill-region' is used on the selection, rather than
;; `delete-region'. (Text selected with the mouse will typically
;; be yankable anyhow.)
-;; non-nil
+;; t
;; The normal case: delete the active region prior to executing
;; the command which will insert replacement text.
+;; <function>
+;; For commands which need to dynamically determine this behaviour.
+;; The function 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)
+ "Delete 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.)
+ t
+ The normal case: delete the active region prior to executing
+ the command which will insert replacement text.
+ FUNCTION
+ For commands which need to dynamically determine this behaviour.
+ FUNCTION should take no argument and 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))))
+ ((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))))
+
(defun delete-selection-pre-hook ()
- (when (and delete-selection-mode transient-mark-mode mark-active
+ "Function run before commands that delete selections are executed.
+Commands which will delete the selection need a `delete-selection'
+property on their symbol; commands which insert text but don't
+have this property won't delete the selection.
+See `delete-selection-helper'."
+ (when (and delete-selection-mode (use-region-p)
(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)
+ (delete-selection-helper (and (symbolp this-command)
+ (get this-command 'delete-selection)))))
+
+(put 'self-insert-command 'delete-selection
+ (lambda ()
+ (not (run-hook-with-args-until-success
+ 'self-insert-uses-region-functions))))
+
(put 'self-insert-iso 'delete-selection t)
(put 'yank 'delete-selection 'yank)