;;; erc-truncate.el --- Functions for truncating ERC buffers
;; Copyright (C) 2003 Free Software Foundation, Inc.
;; Author: Andreas Fuchs <firstname.lastname@example.org>
;; Keywords: IRC, chat, client, Internet, logging
;; This file is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.
;; This file is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING. If not, write to
;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.
;; This implements buffer truncation (and optional log file writing
;; support for the Emacs IRC client. Use `erc-truncate-mode' to switch
;; on. Use `erc-enable-logging' to enable logging of the stuff which
;; is getting truncated.
(defcustom erc-max-buffer-size 30000
"*Maximum size in chars of each ERC buffer. Used only when auto-truncation is enabled.
\(see `erc-truncate-buffer' and `erc-insert-post-hook')."
;;;###autoload (autoload 'erc-truncate-mode "erc-truncate" nil t)
(define-erc-module truncate nil
"Truncate a query buffer if it gets too large.
This prevents the query buffer from getting too large, which can
bring any grown emacs to its knees after a few days worth of
tracking heavy-traffic channels."
((add-hook 'erc-insert-post-hook 'erc-truncate-buffer))
((remove-hook 'erc-insert-post-hook 'erc-truncate-buffer)))
(defun erc-truncate-buffer-to-size (size &optional buffer)
"Truncates the buffer to the size SIZE.
If BUFFER is not provided, the current buffer is assumed. The deleted
region is logged if `erc-logging-enabled' returns non-nil."
;; If buffer is non-nil, but get-buffer does not return anything,
;; then this is a bug. If buffer is a buffer name, get the buffer
;; object. If buffer is nil, use the current buffer.
(if (not buffer)
(setq buffer (current-buffer))
(unless (get-buffer buffer)
(error "erc-truncate-buffer-to-size: %S is not a buffer" buffer)))
(when (> (buffer-size buffer) (+ size 512))
;; Note that when erc-insert-post-hook runs, the buffer is
;; narrowed to the new message. So do this delicate widening.
;; I am not sure, I think this was not recommended behaviour in
;; Emacs 20.
(let ((end (- (point-max) size)))
;; truncate at line boundaries
(setq end (point))
;; try to save the current buffer using
;; `erc-save-buffer-in-logs'. We use this, in case the
;; user has both `erc-save-buffer-in-logs' and
;; `erc-truncate-buffer' in `erc-insert-post-hook'. If
;; this is the case, only the non-saved part of the current
;; buffer should be saved. Rather than appending the
;; deleted part of the buffer to the log file.
;; Alternatively this could be made conditional on:
;; (not (memq 'erc-save-buffer-in-logs
(when (fboundp 'erc-save-buffer-in-logs)
;; disable undoing for the truncating
(let ((inhibit-read-only t))
(delete-region (point-min) end)))
(defun erc-truncate-buffer ()
"Truncates the current buffer to `erc-max-buffer-size'.
Meant to be used in hooks, like `erc-insert-post-hook'."
;;; erc-truncate.el ends here