--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lisp/gnus/gnus-bcklg.el	Mon Aug 13 08:49:20 2007 +0200
@@ -0,0 +1,152 @@
+;;; gnus-bcklg.el --- backlog functions for Gnus
+;; Copyright (C) 1996,97 Free Software Foundation, Inc.
+
+;; Author: Lars Magne Ingebrigtsen <larsi@ifi.uio.no>
+;; Keywords: news
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs 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.
+
+;; GNU Emacs 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.
+
+;;; Commentary:
+
+;;; Code:
+
+(require 'gnus)
+
+;;;
+;;; Buffering of read articles.
+;;;
+
+(defvar gnus-backlog-buffer " *Gnus Backlog*")
+(defvar gnus-backlog-articles nil)
+(defvar gnus-backlog-hashtb nil)
+
+(defun gnus-backlog-buffer ()
+  "Return the backlog buffer."
+  (or (get-buffer gnus-backlog-buffer)
+      (save-excursion
+	(set-buffer (get-buffer-create gnus-backlog-buffer))
+	(buffer-disable-undo (current-buffer))
+	(setq buffer-read-only t)
+	(gnus-add-current-to-buffer-list)
+	(get-buffer gnus-backlog-buffer))))
+
+(defun gnus-backlog-setup ()
+  "Initialize backlog variables."
+  (unless gnus-backlog-hashtb
+    (setq gnus-backlog-hashtb (gnus-make-hashtable 1024))))
+
+(gnus-add-shutdown 'gnus-backlog-shutdown 'gnus)
+
+(defun gnus-backlog-shutdown ()
+  "Clear all backlog variables and buffers."
+  (when (get-buffer gnus-backlog-buffer)
+    (kill-buffer gnus-backlog-buffer))
+  (setq gnus-backlog-hashtb nil
+	gnus-backlog-articles nil))
+
+(defun gnus-backlog-enter-article (group number buffer)
+  (gnus-backlog-setup)
+  (let ((ident (intern (concat group ":" (int-to-string number))
+		       gnus-backlog-hashtb))
+	b)
+    (if (memq ident gnus-backlog-articles)
+	()				; It's already kept.
+      ;; Remove the oldest article, if necessary.
+      (and (numberp gnus-keep-backlog)
+	   (>= (length gnus-backlog-articles) gnus-keep-backlog)
+	   (gnus-backlog-remove-oldest-article))
+      (push ident gnus-backlog-articles)
+      ;; Insert the new article.
+      (save-excursion
+	(set-buffer (gnus-backlog-buffer))
+	(let (buffer-read-only)
+	  (goto-char (point-max))
+	  (unless (bolp)
+	    (insert "\n"))
+	  (setq b (point))
+	  (insert-buffer-substring buffer)
+	  ;; Tag the beginning of the article with the ident.
+	  (gnus-put-text-property b (1+ b) 'gnus-backlog ident))))))
+
+(defun gnus-backlog-remove-oldest-article ()
+  (save-excursion
+    (set-buffer (gnus-backlog-buffer))
+    (goto-char (point-min))
+    (if (zerop (buffer-size))
+	()				; The buffer is empty.
+      (let ((ident (get-text-property (point) 'gnus-backlog))
+	    buffer-read-only)
+	;; Remove the ident from the list of articles.
+	(when ident
+	  (setq gnus-backlog-articles (delq ident gnus-backlog-articles)))
+	;; Delete the article itself.
+	(delete-region
+	 (point) (next-single-property-change
+		  (1+ (point)) 'gnus-backlog nil (point-max)))))))
+
+(defun gnus-backlog-remove-article (group number)
+  "Remove article NUMBER in GROUP from the backlog."
+  (when (numberp number)
+    (gnus-backlog-setup)
+    (let ((ident (intern (concat group ":" (int-to-string number))
+			 gnus-backlog-hashtb))
+	  beg end)
+      (when (memq ident gnus-backlog-articles)
+	;; It was in the backlog.
+	(save-excursion
+	  (set-buffer (gnus-backlog-buffer))
+	  (let (buffer-read-only)
+	    (when (setq beg (text-property-any
+			     (point-min) (point-max) 'gnus-backlog
+			     ident))
+	      ;; Find the end (i. e., the beginning of the next article).
+	      (setq end
+		    (next-single-property-change
+		     (1+ beg) 'gnus-backlog (current-buffer) (point-max)))
+	      (delete-region beg end)
+	      ;; Return success.
+	      t)))))))
+
+(defun gnus-backlog-request-article (group number buffer)
+  (when (numberp number)
+    (gnus-backlog-setup)
+    (let ((ident (intern (concat group ":" (int-to-string number))
+			 gnus-backlog-hashtb))
+	  beg end)
+      (when (memq ident gnus-backlog-articles)
+	;; It was in the backlog.
+	(save-excursion
+	  (set-buffer (gnus-backlog-buffer))
+	  (if (not (setq beg (text-property-any
+			      (point-min) (point-max) 'gnus-backlog
+			      ident)))
+	      ;; It wasn't in the backlog after all.
+	      (ignore
+	       (setq gnus-backlog-articles (delq ident gnus-backlog-articles)))
+	    ;; Find the end (i. e., the beginning of the next article).
+	    (setq end
+		  (next-single-property-change
+		   (1+ beg) 'gnus-backlog (current-buffer) (point-max)))))
+	(let ((buffer-read-only nil))
+	  (erase-buffer)
+	  (insert-buffer-substring gnus-backlog-buffer beg end)
+	  t)))))
+
+(provide 'gnus-bcklg)
+
+;;; gnus-bcklg.el ends here