lisp/erc/erc-truncate.el

   1 ;;; erc-truncate.el --- Functions for truncating ERC buffers
   2
   3 ;; Copyright (C) 2003-2004, 2006-2014 Free Software Foundation, Inc.
   4
   5 ;; Author: Andreas Fuchs <asf@void.at>
   6 ;; Maintainer: FSF
   7 ;; Keywords: IRC, chat, client, Internet, logging
   8
   9 ;; This file is part of GNU Emacs.
  10
  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.
  15
  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.
  20
  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/>.
  23
  24 ;;; Commentary:
  25
  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.
  30
  31 ;;; Code:
  32
  33 (require 'erc)
  34
  35 (defgroup erc-truncate nil
  36   "Truncate buffers when they reach a certain size"
  37   :group 'erc)
  38
  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)
  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.
  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)))
  56
  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.
  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'.
 107 Meant 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 ;; indent-tabs-mode: t
 116 ;; tab-width: 8
 117 ;; End:
 118