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[emacs.git] / lisp / saveplace.el
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1 ;;; saveplace.el --- automatically save place in files
3 ;; Copyright (C) 1993, 1994, 2001 Free Software Foundation, Inc.
5 ;; Author: Karl Fogel <kfogel@red-bean.com>
6 ;; Maintainer: FSF
7 ;; Created: July, 1993
8 ;; Keywords: bookmarks, placeholders
10 ;; This file is part of GNU Emacs.
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 2, or (at your option)
15 ;; any later version.
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.
22 ;; You should have received a copy of the GNU General Public License
23 ;; along with GNU Emacs; see the file COPYING. If not, write to the
24 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
25 ;; Boston, MA 02111-1307, USA.
27 ;;; Commentary:
29 ;; Automatically save place in files, so that visiting them later
30 ;; (even during a different Emacs session) automatically moves point
31 ;; to the saved position, when the file is first found. Uses the
32 ;; value of buffer-local variable save-place to determine whether to
33 ;; save position or not.
35 ;; Thanks to Stefan Schoef, who sent a patch with the
36 ;; `save-place-version-control' stuff in it.
38 ;;; Code:
40 ;; this is what I was using during testing:
41 ;; (define-key ctl-x-map "p" 'toggle-save-place)
43 (defgroup save-place nil
44 "Automatically save place in files."
45 :group 'data)
48 (defvar save-place-alist nil
49 "Alist of saved places to go back to when revisiting files.
50 Each element looks like (FILENAME . POSITION);
51 visiting file FILENAME goes automatically to position POSITION
52 rather than the beginning of the buffer.
53 This alist is saved between Emacs sessions.")
55 (defcustom save-place nil
56 "*Non-nil means automatically save place in each file.
57 This means when you visit a file, point goes to the last place
58 where it was when you previously visited the same file.
59 This variable is automatically buffer-local.
61 If you wish your place in any file to always be automatically saved,
62 simply put this in your `~/.emacs' file:
64 \(setq-default save-place t\)"
65 :type 'boolean
66 :require 'saveplace
67 :group 'save-place)
69 (make-variable-buffer-local 'save-place)
71 (defcustom save-place-file (convert-standard-filename "~/.emacs-places")
72 "*Name of the file that records `save-place-alist' value."
73 :type 'file
74 :group 'save-place)
76 (defcustom save-place-version-control nil
77 "*Controls whether to make numbered backups of master save-place file.
78 It can have four values: t, nil, `never', and `nospecial'. The first
79 three have the same meaning that they do for the variable
80 `version-control', and the final value `nospecial' means just use the
81 value of `version-control'."
82 :type '(radio (const :tag "Unconditionally" t)
83 (const :tag "For VC Files" nil)
84 (const never)
85 (const :tag "Use value of `version-control'" nospecial))
86 :group 'save-place)
88 (defvar save-place-loaded nil
89 "Non-nil means that the `save-place-file' has been loaded.")
91 (defcustom save-place-limit nil
92 "Maximum number of entries to retain in the list; nil means no limit."
93 :type '(choice (integer :tag "Entries" :value 1)
94 (const :tag "No Limit" nil))
95 :group 'save-place)
97 (defun toggle-save-place (&optional parg)
98 "Toggle whether to save your place in this file between sessions.
99 If this mode is enabled, point is recorded when you kill the buffer
100 or exit Emacs. Visiting this file again will go to that position,
101 even in a later Emacs session.
103 If called with a prefix arg, the mode is enabled if and only if
104 the argument is positive.
106 To save places automatically in all files, put this in your `.emacs' file:
108 \(setq-default save-place t\)"
109 (interactive "P")
110 (if (not buffer-file-name)
111 (message "Buffer `%s' not visiting a file" (buffer-name))
112 (if (and save-place (or (not parg) (<= parg 0)))
113 (progn
114 (message "No place will be saved in this file")
115 (setq save-place nil))
116 (message "Place will be saved")
117 (setq save-place t))))
119 (defun save-place-to-alist ()
120 ;; put filename and point in a cons box and then cons that onto the
121 ;; front of the save-place-alist, if save-place is non-nil.
122 ;; Otherwise, just delete that file from the alist.
123 ;; first check to make sure alist has been loaded in from the master
124 ;; file. If not, do so, then feel free to modify the alist. It
125 ;; will be saved again when Emacs is killed.
126 (or save-place-loaded (load-save-place-alist-from-file))
127 (if buffer-file-name
128 (progn
129 (let ((cell (assoc buffer-file-name save-place-alist))
130 (position (if (not (eq major-mode 'hexl-mode))
131 (point)
132 (1+ (hexl-current-address)))))
133 (if cell
134 (setq save-place-alist (delq cell save-place-alist)))
135 (if (and save-place
136 (not (= position 1))) ;; Optimize out the degenerate case.
137 (setq save-place-alist
138 (cons (cons buffer-file-name position)
139 save-place-alist)))))))
141 (defun save-place-alist-to-file ()
142 (let ((file (expand-file-name save-place-file)))
143 (save-excursion
144 (message "Saving places to %s..." file)
145 (set-buffer (get-buffer-create " *Saved Places*"))
146 (delete-region (point-min) (point-max))
147 (print save-place-alist (current-buffer))
148 (let ((version-control
149 (cond
150 ((null save-place-version-control) nil)
151 ((eq 'never save-place-version-control) 'never)
152 ((eq 'nospecial save-place-version-control) version-control)
154 t))))
155 (write-file file)
156 (kill-buffer (current-buffer))
157 (message "Saving places to %s...done" file)))))
159 (defun load-save-place-alist-from-file ()
160 (if (not save-place-loaded)
161 (progn
162 (setq save-place-loaded t)
163 (let ((file (expand-file-name save-place-file)))
164 ;; make sure that the alist does not get overwritten, and then
165 ;; load it if it exists:
166 (if (file-readable-p file)
167 (save-excursion
168 (message "Loading places from %s..." save-place-file)
169 ;; don't want to use find-file because we have been
170 ;; adding hooks to it.
171 (set-buffer (get-buffer-create " *Saved Places*"))
172 (delete-region (point-min) (point-max))
173 (insert-file-contents file)
174 (goto-char (point-min))
175 (setq save-place-alist
176 (car (read-from-string
177 (buffer-substring (point-min) (point-max)))))
179 ;; If there is a limit, and we're over it, then we'll
180 ;; have to truncate the end of the list:
181 (if save-place-limit
182 (if (<= save-place-limit 0)
183 ;; Zero gets special cased. I'm not thrilled
184 ;; with this, but the loop for >= 1 is tight.
185 (setq save-place-alist nil)
186 ;; Else the limit is >= 1, so enforce it by
187 ;; counting and then `setcdr'ing.
188 (let ((s save-place-alist)
189 (count 1))
190 (while s
191 (if (>= count save-place-limit)
192 (setcdr s nil)
193 (setq count (1+ count)))
194 (setq s (cdr s))))))
196 (kill-buffer (current-buffer))
197 (message "Loading places from %s...done" file)))
198 nil))))
200 (defun save-places-to-alist ()
201 ;; go through buffer-list, saving places to alist if save-place is
202 ;; non-nil, deleting them from alist if it is nil.
203 (let ((buf-list (buffer-list)))
204 (while buf-list
205 ;; put this into a save-excursion in case someone is counting on
206 ;; another function in kill-emacs-hook to act on the last buffer
207 ;; they were in:
208 (save-excursion
209 (set-buffer (car buf-list))
210 ;; save-place checks buffer-file-name too, but we can avoid
211 ;; overhead of function call by checking here too.
212 (and buffer-file-name (save-place-to-alist))
213 (setq buf-list (cdr buf-list))))))
215 (defun save-place-find-file-hook ()
216 (or save-place-loaded (load-save-place-alist-from-file))
217 (let ((cell (assoc buffer-file-name save-place-alist)))
218 (if cell
219 (progn
220 (or after-find-file-from-revert-buffer
221 (goto-char (cdr cell)))
222 ;; and make sure it will be saved again for later
223 (setq save-place t)))))
225 (defun save-place-kill-emacs-hook ()
226 ;; First update the alist. This loads the old save-place-file if nec.
227 (save-places-to-alist)
228 ;; Now save the alist in the file, if we have ever loaded the file
229 ;; (including just now).
230 (if save-place-loaded
231 (save-place-alist-to-file)))
233 (add-hook 'find-file-hooks 'save-place-find-file-hook t)
235 (add-hook 'kill-emacs-hook 'save-place-kill-emacs-hook)
237 (add-hook 'kill-buffer-hook 'save-place-to-alist)
239 (provide 'saveplace) ; why not...
241 ;;; saveplace.el ends here