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1 | ;;; saveplace.el --- automatically save place in files. |
2 | ||
3 | ;; Copyright (C) 1993 Free Software Foundation, Inc. | |
4 | ||
5 | ;; Author: Karl Fogel <kfogel@cs.oberlin.edu> | |
6 | ;; Maintainer: FSF | |
7 | ;; Created: July, 1993 | |
8 | ;; Version: 1.0 | |
9 | ;; Keywords: bookmarks, placeholders | |
10 | ||
11 | ;; This file is part of GNU Emacs. | |
12 | ||
13 | ;; GNU Emacs is free software; you can redistribute it and/or modify | |
14 | ;; it under the terms of the GNU General Public License as published by | |
15 | ;; the Free Software Foundation; either version 2, or (at your option) | |
16 | ;; any later version. | |
17 | ||
18 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
19 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
20 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
21 | ;; GNU General Public License for more details. | |
22 | ||
23 | ;; You should have received a copy of the GNU General Public License | |
24 | ;; along with GNU Emacs; see the file COPYING. If not, write to | |
25 | ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. | |
26 | ||
27 | ;; Automatically save place in files, so that visiting them later | |
28 | ;; (even during a different Emacs session) automatically moves point | |
29 | ;; to the saved position, when the file is first found. Uses the | |
30 | ;; value of buffer-local variable save-place to determine whether to | |
31 | ;; save position or not. | |
32 | ;; | |
33 | ;; Don't autoload this, rather, load it, since it modifies | |
34 | ;; find-file-hooks and other hooks. | |
35 | ||
36 | ;; this is what I was using during testing: | |
37 | ;; (define-key ctl-x-map "p" 'toggle-save-place) | |
38 | ||
39 | (defvar save-place-alist nil | |
40 | "Alist of saved places to go back to when revisiting files. | |
41 | Each element looks like (FILENAME . POSITION); | |
42 | visiting file FILENAME goes automatically to position POSITION | |
43 | rather than the beginning of the buffer. | |
44 | This alist is saved between Emacs sessions.") | |
45 | ||
46 | (defvar save-place nil | |
47 | "*Non-nil means automatically save place in each file. | |
48 | This means when you visit a file, point goes to the last place | |
49 | where it was when you previously visited the same file. | |
50 | This variable is automatically buffer-local. | |
51 | ||
52 | If you wish your place in any file to always be automatically saved, | |
53 | simply put this in your `~/.emacs' file: | |
54 | ||
55 | \(setq-default save-place t\)") | |
56 | ||
57 | (make-variable-buffer-local 'save-place) | |
58 | ||
59 | (defvar save-place-file "~/.emacs-places" | |
60 | "*Name of the file that records `save-place-alist' value.") | |
61 | ||
62 | (defvar save-place-loaded nil | |
63 | "Non-nil means that the `save-place-file' has been loaded.") | |
64 | ||
65 | (defun toggle-save-place (&optional parg) | |
66 | "Toggle whether to save your place in this file between sessions. | |
67 | If this mode is enabled, point is recorded when you kill the buffer | |
68 | or exit Emacs. Visiting this file again will go to that position, | |
69 | even in a later Emacs session. | |
70 | ||
71 | If called with a prefix arg, the mode is enabled if and only if | |
72 | the argument is positive. | |
73 | ||
74 | To save places automatically in all files, put this in your `.emacs' file: | |
75 | ||
76 | \(setq-default save-place t\)" | |
77 | (interactive "P") | |
78 | (if (not buffer-file-name) | |
79 | (message | |
80 | (format "Buffer \"%s\" not visiting a file." (buffer-name))) | |
81 | (if (and save-place (or (not parg) (<= parg 0))) | |
82 | (progn | |
83 | (message "No place will be saved in this file.") | |
84 | (setq save-place nil)) | |
85 | (message "Place will be saved.") | |
86 | (setq save-place t)))) | |
87 | ||
88 | (defun save-place-to-alist () | |
89 | ;; put filename and point in a cons box and then cons that onto the | |
90 | ;; front of the save-place-alist, if save-place is non-nil. | |
91 | ;; Otherwise, just delete that file from the alist. | |
92 | ;; first check to make sure alist has been loaded in from the master | |
93 | ;; file. If not, do so, then feel free to modify the alist. It | |
94 | ;; will be saved again when Emacs is killed. | |
95 | (or save-place-loaded (load-save-place-alist-from-file)) | |
96 | (if buffer-file-name | |
97 | (progn | |
98 | (let ((cell (assoc buffer-file-name save-place-alist))) | |
99 | (if cell | |
100 | (setq save-place-alist (delq cell save-place-alist)))) | |
101 | (if save-place | |
102 | (setq save-place-alist | |
103 | (cons (cons buffer-file-name (point)) | |
104 | save-place-alist)))))) | |
105 | ||
106 | (defun save-place-alist-to-file () | |
107 | (let ((file (expand-file-name save-place-file))) | |
108 | (save-excursion | |
109 | (message (format "Saving places to %s..." file)) | |
110 | (set-buffer (get-buffer-create " *Saved Places*")) | |
111 | (delete-region (point-min) (point-max)) | |
112 | (if (file-readable-p file) | |
113 | (insert-file-contents file)) | |
114 | (delete-region (point-min) (point-max)) | |
115 | (goto-char (point-min)) | |
116 | (print save-place-alist (current-buffer)) | |
117 | (write-file file) | |
118 | (kill-buffer (current-buffer)) | |
119 | (message (format "Saving places to %s... done." file))))) | |
120 | ||
121 | (defun load-save-place-alist-from-file () | |
122 | (if (not save-place-loaded) | |
123 | (progn | |
124 | (setq save-place-loaded t) | |
125 | (let ((file (expand-file-name save-place-file))) | |
126 | ;; make sure that the alist does not get overwritten, and then | |
127 | ;; load it if it exists: | |
128 | (if (file-readable-p file) | |
129 | (save-excursion | |
130 | (message (format "Loading places from %s..." | |
131 | save-place-file)) | |
132 | ;; don't want to use find-file because we have been | |
133 | ;; adding hooks to it. | |
134 | (set-buffer (get-buffer-create " *Saved Places*")) | |
135 | (delete-region (point-min) (point-max)) | |
136 | (insert-file-contents file) | |
137 | (goto-char (point-min)) | |
138 | (setq save-place-alist | |
139 | (car (read-from-string | |
140 | (buffer-substring (point-min) (point-max))))) | |
141 | (kill-buffer (current-buffer)) | |
142 | (message (format "Loading places from %s... done." file)) | |
143 | t) | |
144 | t) | |
145 | nil)))) | |
146 | ||
147 | (defun save-places-to-alist () | |
148 | ;; go through buffer-list, saving places to alist if save-place is | |
149 | ;; non-nil, deleting them from alist if it is nil. | |
150 | (let ((buf-list (buffer-list))) | |
151 | (while buf-list | |
152 | ;; put this into a save-excursion in case someone is counting on | |
153 | ;; another function in kill-emacs-hook to act on the last buffer | |
154 | ;; they were in: | |
155 | (save-excursion | |
156 | (set-buffer (car buf-list)) | |
157 | ;; save-place checks buffer-file-name too, but we can avoid | |
158 | ;; overhead of function call by checking here too. | |
159 | (and buffer-file-name (save-place-to-alist)) | |
160 | (setq buf-list (cdr buf-list)))))) | |
161 | ||
162 | (add-hook | |
163 | 'find-file-hooks | |
164 | (function | |
165 | (lambda () | |
166 | (or save-place-loaded (load-save-place-alist-from-file)) | |
167 | (let ((cell (assoc buffer-file-name save-place-alist))) | |
168 | (if cell | |
169 | (progn | |
170 | (goto-char (cdr cell)) | |
171 | ;; and make sure it will be saved again for later. | |
172 | (setq save-place t))))))) | |
173 | ||
174 | (add-hook 'kill-emacs-hook | |
175 | (function | |
176 | (lambda () | |
177 | (progn | |
178 | (save-places-to-alist) | |
179 | (save-place-alist-to-file))))) | |
180 | ||
181 | (add-hook 'kill-buffer-hook 'save-place-to-alist) | |
182 | ||
183 | (provide 'saveplace) ; why not... | |
184 | ||
185 | ;;; saveplace.el ends here | |
186 |