lisp/delsel.el

   1 ;;; delsel.el --- delete selection if you insert
   2
   3 ;; Copyright (C) 1992, 1997-1998, 2001-2012 Free Software Foundation, Inc.
   4
   5 ;; Author: Matthieu Devin <devin@lucid.com>
   6 ;; Maintainer: FSF
   7 ;; Created: 14 Jul 92
   8 ;; Keywords: convenience emulations
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software: you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation, either version 3 of the License, or
  15 ;; (at your option) any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  24
  25 ;;; Commentary:
  26
  27 ;; This file makes the active region be pending delete, meaning that
  28 ;; text inserted while the region is active will replace the region contents.
  29 ;; This is a popular behavior of personal computers text editors.
  30
  31 ;; Interface:
  32
  33 ;; Commands which will delete the selection need a 'delete-selection
  34 ;; property on their symbols; commands which insert text but don't
  35 ;; have this property won't delete the selection.  It can be one of
  36 ;; the values:
  37 ;;  'yank
  38 ;;      For commands which do a yank; ensures the region about to be
  39 ;;      deleted isn't yanked.
  40 ;;  'supersede
  41 ;;      Delete the active region and ignore the current command,
  42 ;;      i.e. the command will just delete the region.
  43 ;;  'kill
  44 ;;      `kill-region' is used on the selection, rather than
  45 ;;      `delete-region'.  (Text selected with the mouse will typically
  46 ;;      be yankable anyhow.)
  47 ;;  non-nil
  48 ;;      The normal case: delete the active region prior to executing
  49 ;;      the command which will insert replacement text.
  50
  51 ;;; Code:
  52
  53 ;;;###autoload
  54 (defalias 'pending-delete-mode 'delete-selection-mode)
  55
  56 ;;;###autoload
  57 (define-minor-mode delete-selection-mode
  58   "Toggle Delete Selection mode.
  59 With a prefix argument ARG, enable Delete Selection mode if ARG
  60 is positive, and disable it otherwise.  If called from Lisp,
  61 enable the mode if ARG is omitted or nil.
  62
  63 When Delete Selection mode is enabled, Transient Mark mode is also
  64 enabled and typed text replaces the selection if the selection is
  65 active.  Otherwise, typed text is just inserted at point regardless of
  66 any selection."
  67   :global t :group 'editing-basics
  68   (if (not delete-selection-mode)
  69       (remove-hook 'pre-command-hook 'delete-selection-pre-hook)
  70     (add-hook 'pre-command-hook 'delete-selection-pre-hook)
  71     (transient-mark-mode t)))
  72
  73 (defun delete-active-region (&optional killp)
  74   (if killp
  75       (kill-region (point) (mark))
  76     (delete-region (point) (mark)))
  77   t)
  78
  79 (defun delete-selection-pre-hook ()
  80   (when (and delete-selection-mode transient-mark-mode mark-active
  81              (not buffer-read-only))
  82     (let ((type (and (symbolp this-command)
  83                      (get this-command 'delete-selection))))
  84       (condition-case data
  85           (cond ((eq type 'kill)
  86                  (delete-active-region t))
  87                 ((eq type 'yank)
  88                  ;; Before a yank command, make sure we don't yank the
  89                  ;; head of the kill-ring that really comes from the
  90                  ;; currently active region we are going to delete.
  91                  ;; That would make yank a no-op.
  92                  (when (and (string= (buffer-substring-no-properties (point) (mark))
  93                                      (car kill-ring))
  94                             (fboundp 'mouse-region-match)
  95                             (mouse-region-match))
  96                    (current-kill 1))
  97                  (delete-active-region))
  98                 ((eq type 'supersede)
  99                  (let ((empty-region (= (point) (mark))))
 100                    (delete-active-region)
 101                    (unless empty-region
 102                      (setq this-command 'ignore))))
 103                 (type
 104                  (delete-active-region)
 105                  (if (and overwrite-mode (eq this-command 'self-insert-command))
 106                    (let ((overwrite-mode nil))
 107                      (self-insert-command (prefix-numeric-value current-prefix-arg))
 108                      (setq this-command 'ignore)))))
 109         (file-supersession
 110          ;; If ask-user-about-supersession-threat signals an error,
 111          ;; stop safe_run_hooks from clearing out pre-command-hook.
 112          (and (eq inhibit-quit 'pre-command-hook)
 113               (setq inhibit-quit 'delete-selection-dummy))
 114          (signal 'file-supersession (cdr data)))
 115         (text-read-only
 116          ;; This signal may come either from `delete-active-region' or
 117          ;; `self-insert-command' (when `overwrite-mode' is non-nil).
 118          ;; To avoid clearing out `pre-command-hook' we handle this case
 119          ;; by issuing a simple message.  Note, however, that we do not
 120          ;; handle all related problems: When read-only text ends before
 121          ;; the end of the region, the latter is not deleted but any
 122          ;; subsequent insertion will succeed.  We could avoid this case
 123          ;; by doing a (setq this-command 'ignore) here.  This would,
 124          ;; however, still not handle the case where read-only text ends
 125          ;; precisely where the region starts: In that case the deletion
 126          ;; would succeed but the subsequent insertion would fail with a
 127          ;; text-read-only error.  To handle that case we would have to
 128          ;; investigate text properties at both ends of the region and
 129          ;; skip the deletion when inserting text is forbidden there.
 130          (message "Text is read-only") (ding))))))
 131
 132 (put 'self-insert-command 'delete-selection t)
 133 (put 'self-insert-iso 'delete-selection t)
 134
 135 (put 'yank 'delete-selection 'yank)
 136 (put 'clipboard-yank 'delete-selection 'yank)
 137 (put 'insert-register 'delete-selection t)
 138
 139 (put 'delete-backward-char 'delete-selection 'supersede)
 140 (put 'backward-delete-char-untabify 'delete-selection 'supersede)
 141 (put 'delete-char 'delete-selection 'supersede)
 142
 143 (put 'newline-and-indent 'delete-selection t)
 144 (put 'newline 'delete-selection t)
 145 (put 'open-line 'delete-selection 'kill)
 146
 147 ;; This is very useful for canceling a selection in the minibuffer without
 148 ;; aborting the minibuffer.
 149 (defun minibuffer-keyboard-quit ()
 150   "Abort recursive edit.
 151 In Delete Selection mode, if the mark is active, just deactivate it;
 152 then it takes a second \\[keyboard-quit] to abort the minibuffer."
 153   (interactive)
 154   (if (and delete-selection-mode transient-mark-mode mark-active)
 155       (setq deactivate-mark t)
 156     (abort-recursive-edit)))
 157
 158 (define-key minibuffer-local-map "\C-g" 'minibuffer-keyboard-quit)
 159 (define-key minibuffer-local-ns-map "\C-g" 'minibuffer-keyboard-quit)
 160 (define-key minibuffer-local-completion-map "\C-g" 'minibuffer-keyboard-quit)
 161 (define-key minibuffer-local-must-match-map "\C-g" 'minibuffer-keyboard-quit)
 162 (define-key minibuffer-local-isearch-map "\C-g" 'minibuffer-keyboard-quit)
 163
 164 (defun delsel-unload-function ()
 165   "Unload the Delete Selection library."
 166   (define-key minibuffer-local-map "\C-g" 'abort-recursive-edit)
 167   (define-key minibuffer-local-ns-map "\C-g" 'abort-recursive-edit)
 168   (define-key minibuffer-local-completion-map "\C-g" 'abort-recursive-edit)
 169   (define-key minibuffer-local-must-match-map "\C-g" 'abort-recursive-edit)
 170   (define-key minibuffer-local-isearch-map "\C-g" 'abort-recursive-edit)
 171   (dolist (sym '(self-insert-command self-insert-iso yank clipboard-yank
 172                  insert-register delete-backward-char backward-delete-char-untabify
 173                  delete-char newline-and-indent newline open-line))
 174     (put sym 'delete-selection nil))
 175   ;; continue standard unloading
 176   nil)
 177
 178 (provide 'delsel)
 179
 180 ;;; delsel.el ends here