*** empty log message ***
[emacs.git] / lisp / saveplace.el
blob5ac3f344c62ddf64e9de550de50945b518b03ad3
1 ;;; saveplace.el --- automatically save place in files.
3 ;; Copyright (C) 1993, 1994 Free Software Foundation, Inc.
5 ;; Author: Karl Fogel <kfogel@cs.oberlin.edu>
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 :group 'save-place)
68 (make-variable-buffer-local 'save-place)
70 (defcustom save-place-file (convert-standard-filename "~/.emacs-places")
71 "*Name of the file that records `save-place-alist' value."
72 :type 'file
73 :group 'save-place)
75 (defcustom save-place-version-control nil
76 "*Controls whether to make numbered backups of master save-place file.
77 It can have four values: t, nil, `never', and `nospecial'. The first
78 three have the same meaning that they do for the variable
79 `version-control', and the final value `nospecial' means just use the
80 value of `version-control'."
81 :type '(radio (const :tag "Unconditionally" t)
82 (const :tag "For VC Files" nil)
83 (const never)
84 (const :tag "Use value of `version-control'" nospecial))
85 :group 'save-place)
87 (defvar save-place-loaded nil
88 "Non-nil means that the `save-place-file' has been loaded.")
90 (defcustom save-place-limit nil
91 "Maximum number of entries to retain in the list; nil means no limit."
92 :type '(choice (integer :tag "Entries" :value 1)
93 (const :tag "No Limit" nil))
94 :group 'save-place)
96 (defun toggle-save-place (&optional parg)
97 "Toggle whether to save your place in this file between sessions.
98 If this mode is enabled, point is recorded when you kill the buffer
99 or exit Emacs. Visiting this file again will go to that position,
100 even in a later Emacs session.
102 If called with a prefix arg, the mode is enabled if and only if
103 the argument is positive.
105 To save places automatically in all files, put this in your `.emacs' file:
107 \(setq-default save-place t\)"
108 (interactive "P")
109 (if (not buffer-file-name)
110 (message "Buffer `%s' not visiting a file" (buffer-name))
111 (if (and save-place (or (not parg) (<= parg 0)))
112 (progn
113 (message "No place will be saved in this file")
114 (setq save-place nil))
115 (message "Place will be saved")
116 (setq save-place t))))
118 (defun save-place-to-alist ()
119 ;; put filename and point in a cons box and then cons that onto the
120 ;; front of the save-place-alist, if save-place is non-nil.
121 ;; Otherwise, just delete that file from the alist.
122 ;; first check to make sure alist has been loaded in from the master
123 ;; file. If not, do so, then feel free to modify the alist. It
124 ;; will be saved again when Emacs is killed.
125 (or save-place-loaded (load-save-place-alist-from-file))
126 (if buffer-file-name
127 (progn
128 (let ((cell (assoc buffer-file-name save-place-alist))
129 (position (if (not (eq major-mode 'hexl-mode))
130 (point)
131 (1+ (hexl-current-address)))))
132 (if cell
133 (setq save-place-alist (delq cell save-place-alist)))
134 (if (and save-place
135 (not (= position 1))) ;; Optimize out the degenerate case.
136 (setq save-place-alist
137 (cons (cons buffer-file-name position)
138 save-place-alist)))))))
140 (defun save-place-alist-to-file ()
141 (let ((file (expand-file-name save-place-file)))
142 (save-excursion
143 (message "Saving places to %s..." file)
144 (set-buffer (get-buffer-create " *Saved Places*"))
145 (delete-region (point-min) (point-max))
146 (if (file-readable-p file)
147 (insert-file-contents file))
148 (delete-region (point-min) (point-max))
149 (goto-char (point-min))
150 (print save-place-alist (current-buffer))
151 (let ((version-control
152 (cond
153 ((null save-place-version-control) nil)
154 ((eq 'never save-place-version-control) 'never)
155 ((eq 'nospecial save-place-version-control) version-control)
157 t))))
158 (write-file file)
159 (kill-buffer (current-buffer))
160 (message "Saving places to %s...done" file)))))
162 (defun load-save-place-alist-from-file ()
163 (if (not save-place-loaded)
164 (progn
165 (setq save-place-loaded t)
166 (let ((file (expand-file-name save-place-file)))
167 ;; make sure that the alist does not get overwritten, and then
168 ;; load it if it exists:
169 (if (file-readable-p file)
170 (save-excursion
171 (message "Loading places from %s..." save-place-file)
172 ;; don't want to use find-file because we have been
173 ;; adding hooks to it.
174 (set-buffer (get-buffer-create " *Saved Places*"))
175 (delete-region (point-min) (point-max))
176 (insert-file-contents file)
177 (goto-char (point-min))
178 (setq save-place-alist
179 (car (read-from-string
180 (buffer-substring (point-min) (point-max)))))
182 ;; If there is a limit, and we're over it, then we'll
183 ;; have to truncate the end of the list:
184 (if save-place-limit
185 (if (<= save-place-limit 0)
186 ;; Zero gets special cased. I'm not thrilled
187 ;; with this, but the loop for >= 1 is tight.
188 (setq save-place-alist nil)
189 ;; Else the limit is >= 1, so enforce it by
190 ;; counting and then `setcdr'ing.
191 (let ((s save-place-alist)
192 (count 1))
193 (while s
194 (if (>= count save-place-limit)
195 (setcdr s nil)
196 (setq count (1+ count)))
197 (setq s (cdr s))))))
199 (kill-buffer (current-buffer))
200 (message "Loading places from %s...done" file)))
201 nil))))
203 (defun save-places-to-alist ()
204 ;; go through buffer-list, saving places to alist if save-place is
205 ;; non-nil, deleting them from alist if it is nil.
206 (let ((buf-list (buffer-list)))
207 (while buf-list
208 ;; put this into a save-excursion in case someone is counting on
209 ;; another function in kill-emacs-hook to act on the last buffer
210 ;; they were in:
211 (save-excursion
212 (set-buffer (car buf-list))
213 ;; save-place checks buffer-file-name too, but we can avoid
214 ;; overhead of function call by checking here too.
215 (and buffer-file-name (save-place-to-alist))
216 (setq buf-list (cdr buf-list))))))
218 (defun save-place-find-file-hook ()
219 (or save-place-loaded (load-save-place-alist-from-file))
220 (let ((cell (assoc buffer-file-name save-place-alist)))
221 (if cell
222 (progn
223 (or after-find-file-from-revert-buffer
224 (goto-char (cdr cell)))
225 ;; and make sure it will be saved again for later
226 (setq save-place t)))))
228 (defun save-place-kill-emacs-hook ()
229 ;; First update the alist. This loads the old save-place-file if nec.
230 (save-places-to-alist)
231 ;; Now save the alist in the file, if we have ever loaded the file
232 ;; (including just now).
233 (if save-place-loaded
234 (save-place-alist-to-file)))
236 (add-hook 'find-file-hooks 'save-place-find-file-hook t)
238 (add-hook 'kill-emacs-hook 'save-place-kill-emacs-hook)
240 (add-hook 'kill-buffer-hook 'save-place-to-alist)
242 (provide 'saveplace) ; why not...
244 ;;; saveplace.el ends here