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comparison lisp/packages/saveplace.el @ 0:376386a54a3c r19-14

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date Mon, 13 Aug 2007 08:45:50 +0200
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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 XEmacs.
12
13 ;; XEmacs is free software; you can redistribute it and/or modify it
14 ;; 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 ;; XEmacs is distributed in the hope that it will be useful, but
19 ;; WITHOUT ANY WARRANTY; without even the implied warranty of
20 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
21 ;; General Public License for more details.
22
23 ;; You should have received a copy of the GNU General Public License
24 ;; along with XEmacs; see the file COPYING. If not, write to the Free
25 ;; Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
26
27 ;;; Synched up with: Not synched with FSF but close to 19.30.
28
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.
34 ;;
35 ;; Don't autoload this, rather, load it, since it modifies
36 ;; find-file-hooks and other hooks.
37
38 ;; this is what I was using during testing:
39 ;; (define-key ctl-x-map "p" 'toggle-save-place)
40
41 (defvar save-place-alist nil
42 "Alist of saved places to go back to when revisiting files.
43 Each element looks like (FILENAME . POSITION);
44 visiting file FILENAME goes automatically to position POSITION
45 rather than the beginning of the buffer.
46 This alist is saved between Emacs sessions.")
47
48 (defvar save-place nil
49 "*Non-nil means automatically save place in each file.
50 This means when you visit a file, point goes to the last place
51 where it was when you previously visited the same file.
52 This variable is automatically buffer-local.
53
54 If you wish your place in any file to always be automatically saved,
55 simply put this in your `~/.emacs' file:
56
57 \(setq-default save-place t\)")
58
59 (make-variable-buffer-local 'save-place)
60
61 (defvar save-place-file "~/.emacs-places"
62 "*Name of the file that records `save-place-alist' value.")
63
64 (defvar save-place-loaded nil
65 "Non-nil means that the `save-place-file' has been loaded.")
66
67 (defun toggle-save-place (&optional parg)
68 "Toggle whether to save your place in this file between sessions.
69 If this mode is enabled, point is recorded when you kill the buffer
70 or exit Emacs. Visiting this file again will go to that position,
71 even in a later Emacs session.
72
73 If called with a prefix arg, the mode is enabled if and only if
74 the argument is positive.
75
76 To save places automatically in all files, put this in your `.emacs' file:
77
78 \(setq-default save-place t\)"
79 (interactive "P")
80 (if (not buffer-file-name)
81 (message
82 (format "Buffer \"%s\" not visiting a file." (buffer-name)))
83 (if (and save-place (or (not parg) (<= parg 0)))
84 (progn
85 (message "No place will be saved in this file.")
86 (setq save-place nil))
87 (message "Place will be saved.")
88 (setq save-place t))))
89
90 (defun save-place-to-alist ()
91 ;; put filename and point in a cons box and then cons that onto the
92 ;; front of the save-place-alist, if save-place is non-nil.
93 ;; Otherwise, just delete that file from the alist.
94 ;; first check to make sure alist has been loaded in from the master
95 ;; file. If not, do so, then feel free to modify the alist. It
96 ;; will be saved again when Emacs is killed.
97 (or save-place-loaded (load-save-place-alist-from-file))
98 (if buffer-file-name
99 (progn
100 (let ((cell (assoc buffer-file-name save-place-alist)))
101 (if cell
102 (setq save-place-alist (delq cell save-place-alist))))
103 (if save-place
104 (setq save-place-alist
105 (cons (cons buffer-file-name (point))
106 save-place-alist))))))
107
108 (defun save-place-alist-to-file ()
109 (let ((file (expand-file-name save-place-file)))
110 (save-excursion
111 (message (format "Saving places to %s..." file))
112 (set-buffer (get-buffer-create " *Saved Places*"))
113 (delete-region (point-min) (point-max))
114 (if (file-readable-p file)
115 (insert-file-contents file))
116 (delete-region (point-min) (point-max))
117 (goto-char (point-min))
118 (print save-place-alist (current-buffer))
119 (write-file file)
120 (kill-buffer (current-buffer))
121 (message (format "Saving places to %s... done." file)))))
122
123 (defun load-save-place-alist-from-file ()
124 (if (not save-place-loaded)
125 (progn
126 (setq save-place-loaded t)
127 (let ((file (expand-file-name save-place-file)))
128 ;; make sure that the alist does not get overwritten, and then
129 ;; load it if it exists:
130 (if (file-readable-p file)
131 (save-excursion
132 (message (format "Loading places from %s..."
133 save-place-file))
134 ;; don't want to use find-file because we have been
135 ;; adding hooks to it.
136 (set-buffer (get-buffer-create " *Saved Places*"))
137 (delete-region (point-min) (point-max))
138 (insert-file-contents file)
139 (goto-char (point-min))
140 (setq save-place-alist
141 (car (read-from-string
142 (buffer-substring (point-min) (point-max)))))
143 (kill-buffer (current-buffer))
144 (message (format "Loading places from %s... done." file))
145 t)
146 t)
147 nil))))
148
149 (defun save-places-to-alist ()
150 ;; go through buffer-list, saving places to alist if save-place is
151 ;; non-nil, deleting them from alist if it is nil.
152 (let ((buf-list (buffer-list)))
153 (while buf-list
154 ;; put this into a save-excursion in case someone is counting on
155 ;; another function in kill-emacs-hook to act on the last buffer
156 ;; they were in:
157 (save-excursion
158 (set-buffer (car buf-list))
159 ;; save-place checks buffer-file-name too, but we can avoid
160 ;; overhead of function call by checking here too.
161 (and buffer-file-name (save-place-to-alist))
162 (setq buf-list (cdr buf-list))))))
163
164 (add-hook
165 'find-file-hooks
166 (function
167 (lambda ()
168 (or save-place-loaded (load-save-place-alist-from-file))
169 (let ((cell (assoc buffer-file-name save-place-alist)))
170 (if cell
171 (progn
172 (goto-char (cdr cell))
173 ;; and make sure it will be saved again for later.
174 (setq save-place t)))))))
175
176 (add-hook 'kill-emacs-hook
177 (function
178 (lambda ()
179 (progn
180 (save-places-to-alist)
181 (save-place-alist-to-file)))))
182
183 (add-hook 'kill-buffer-hook 'save-place-to-alist)
184
185 (provide 'saveplace) ; why not...
186
187 ;;; saveplace.el ends here
188