[gnus] / lisp / gnus-bcklg.el

;;; gnus-bcklg.el --- backlog functions for Gnus

;; Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
;;   2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.

;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
;; 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 3 of the License, 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.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;;; Code:

(eval-when-compile (require 'cl))

(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 (gnus-get-buffer-create gnus-backlog-buffer))
        (buffer-disable-undo)
        (setq buffer-read-only t)
        (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."
  (interactive)
  (when (get-buffer gnus-backlog-buffer)
    (gnus-kill-buffer gnus-backlog-buffer))
  (setq gnus-backlog-hashtb nil
        gnus-backlog-articles nil))

(defun gnus-backlog-enter-article (group number buffer)
  (when (and (numberp number)
             (not (string-match "^nnvirtual" group)))
    (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.
            (if (> (point-max) b)
              (gnus-put-text-property b (1+ b) 'gnus-backlog ident)
              (gnus-error 3 "Article %d is blank" number))))))))

(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))
          (setq gnus-backlog-articles (delq ident gnus-backlog-articles)))))))

(defun gnus-backlog-request-article (group number &optional buffer)
  (when (and (numberp number)
             (not (string-match "^nnvirtual" group)))
    (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)))))
        (save-excursion
          (and buffer (set-buffer buffer))
          (let ((buffer-read-only nil))
            (erase-buffer)
            (insert-buffer-substring gnus-backlog-buffer beg end)))
        t))))

(provide 'gnus-bcklg)

;; arch-tag: 66259e56-505a-4bba-8a0d-3552c5b94e39
;;; gnus-bcklg.el ends here