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[emacs.git] / lisp / erc / erc-truncate.el
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1 ;;; erc-truncate.el --- Functions for truncating ERC buffers
3 ;; Copyright (C) 2003-2004, 2006-2017 Free Software Foundation, Inc.
5 ;; Author: Andreas Fuchs <asf@void.at>
6 ;; Maintainer: emacs-devel@gnu.org
7 ;; Keywords: IRC, chat, client, Internet, logging
9 ;; This file is part of GNU Emacs.
11 ;; GNU Emacs is free software: you can redistribute it and/or modify
12 ;; it under the terms of the GNU General Public License as published by
13 ;; the Free Software Foundation, either version 3 of the License, or
14 ;; (at your option) any later version.
16 ;; GNU Emacs is distributed in the hope that it will be useful,
17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 ;; GNU General Public License for more details.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
24 ;;; Commentary:
26 ;; This implements buffer truncation (and optional log file writing
27 ;; support for the Emacs IRC client. Use `erc-truncate-mode' to switch
28 ;; on. Use `erc-enable-logging' to enable logging of the stuff which
29 ;; is getting truncated.
31 ;;; Code:
33 (require 'erc)
35 (defgroup erc-truncate nil
36 "Truncate buffers when they reach a certain size"
37 :group 'erc)
39 (defcustom erc-max-buffer-size 30000
40 "Maximum size in chars of each ERC buffer.
41 Used only when auto-truncation is enabled.
42 \(see `erc-truncate-buffer' and `erc-insert-post-hook')."
43 :group 'erc-truncate
44 :type 'integer)
46 ;;;###autoload (autoload 'erc-truncate-mode "erc-truncate" nil t)
47 (define-erc-module truncate nil
48 "Truncate a query buffer if it gets too large.
49 This prevents the query buffer from getting too large, which can
50 bring any grown Emacs to its knees after a few days worth of
51 tracking heavy-traffic channels."
52 ;;enable
53 ((add-hook 'erc-insert-post-hook 'erc-truncate-buffer))
54 ;; disable
55 ((remove-hook 'erc-insert-post-hook 'erc-truncate-buffer)))
57 ;;;###autoload
58 (defun erc-truncate-buffer-to-size (size &optional buffer)
59 "Truncates the buffer to the size SIZE.
60 If BUFFER is not provided, the current buffer is assumed. The deleted
61 region is logged if `erc-logging-enabled' returns non-nil."
62 ;; If buffer is non-nil, but get-buffer does not return anything,
63 ;; then this is a bug. If buffer is a buffer name, get the buffer
64 ;; object. If buffer is nil, use the current buffer.
65 (if (not buffer)
66 (setq buffer (current-buffer))
67 (unless (get-buffer buffer)
68 (error "erc-truncate-buffer-to-size: %S is not a buffer" buffer)))
69 (when (> (buffer-size buffer) (+ size 512))
70 (with-current-buffer buffer
71 ;; Note that when erc-insert-post-hook runs, the buffer is
72 ;; narrowed to the new message. So do this delicate widening.
73 ;; I am not sure, I think this was not recommended behavior in
74 ;; Emacs 20.
75 (save-restriction
76 (widen)
77 (let ((end (- erc-insert-marker size)))
78 ;; truncate at line boundaries
79 (goto-char end)
80 (beginning-of-line)
81 (setq end (point))
82 ;; try to save the current buffer using
83 ;; `erc-save-buffer-in-logs'. We use this, in case the
84 ;; user has both `erc-save-buffer-in-logs' and
85 ;; `erc-truncate-buffer' in `erc-insert-post-hook'. If
86 ;; this is the case, only the non-saved part of the current
87 ;; buffer should be saved. Rather than appending the
88 ;; deleted part of the buffer to the log file.
90 ;; Alternatively this could be made conditional on:
91 ;; (not (memq 'erc-save-buffer-in-logs
92 ;; erc-insert-post-hook))
93 ;; Comments?
94 (when (and (boundp 'erc-enable-logging)
95 erc-enable-logging
96 (erc-logging-enabled buffer))
97 (erc-save-buffer-in-logs))
98 ;; disable undoing for the truncating
99 (buffer-disable-undo)
100 (let ((inhibit-read-only t))
101 (delete-region (point-min) end)))
102 (buffer-enable-undo)))))
104 ;;;###autoload
105 (defun erc-truncate-buffer ()
106 "Truncates the current buffer to `erc-max-buffer-size'.
107 Meant to be used in hooks, like `erc-insert-post-hook'."
108 (interactive)
109 (erc-truncate-buffer-to-size erc-max-buffer-size))
111 (provide 'erc-truncate)
112 ;;; erc-truncate.el ends here
114 ;; Local Variables:
115 ;; indent-tabs-mode: t
116 ;; tab-width: 8
117 ;; End: