1;;; erc-truncate.el --- Functions for truncating ERC buffers  -*- lexical-binding: t; -*-
2
3;; Copyright (C) 2003-2004, 2006-2021 Free Software Foundation, Inc.
4
5;; Author: Andreas Fuchs <asf@void.at>
6;; Maintainer: Amin Bandali <bandali@gnu.org>
7;; URL: https://www.emacswiki.org/emacs/ErcTruncation
8;; Keywords: IRC, chat, client, Internet, logging
9
10;; This file is part of GNU Emacs.
11
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 3 of the License, or
15;; (at your option) any later version.
16
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.
21
22;; You should have received a copy of the GNU General Public License
23;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
24
25;;; Commentary:
26
27;; This implements buffer truncation (and optional log file writing
28;; support for the Emacs IRC client.  Use `erc-truncate-mode' to switch
29;; on.  Use `erc-enable-logging' to enable logging of the stuff which
30;; is getting truncated.
31
32;;; Code:
33
34(require 'erc)
35
36(defgroup erc-truncate nil
37  "Truncate buffers when they reach a certain size."
38  :group 'erc)
39
40(defcustom erc-max-buffer-size 30000
41  "Maximum size in chars of each ERC buffer.
42Used only when auto-truncation is enabled.
43\(see `erc-truncate-buffer' and `erc-insert-post-hook')."
44  :type 'integer)
45
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.
49This prevents the query buffer from getting too large, which can
50bring any grown Emacs to its knees after a few days worth of
51tracking 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)))
56
57;;;###autoload
58(defun erc-truncate-buffer-to-size (size &optional buffer)
59  "Truncates the buffer to the size SIZE.
60If BUFFER is not provided, the current buffer is assumed.  The deleted
61region 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.
89	  ;;
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)))))
103
104;;;###autoload
105(defun erc-truncate-buffer ()
106  "Truncates the current buffer to `erc-max-buffer-size'.
107Meant to be used in hooks, like `erc-insert-post-hook'."
108  (interactive)
109  (erc-truncate-buffer-to-size erc-max-buffer-size))
110
111(provide 'erc-truncate)
112;;; erc-truncate.el ends here
113;;
114;; Local Variables:
115;; generated-autoload-file: "erc-loaddefs.el"
116;; End:
117