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emacs/lisp/gnus/gnus-bcklg.el
2024-01-02 09:47:10 +08:00

141 lines
4.7 KiB
EmacsLisp

;;; gnus-bcklg.el --- backlog functions for Gnus -*- lexical-binding: t; -*-
;; Copyright (C) 1996-2024 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 <https://www.gnu.org/licenses/>.
;;; Commentary:
;; The backlog caches the text of a certain number of read articles in
;; a separate buffer, so they can be retrieved quickly if the user
;; opens them again. Also see `gnus-keep-backlog'.
;;; Code:
(require 'gnus)
(defvar gnus-backlog-buffer " *Gnus Backlog*")
(defvar gnus-backlog-articles '())
(defun gnus-backlog-buffer ()
"Return the backlog buffer."
(or (get-buffer gnus-backlog-buffer)
(with-current-buffer (gnus-get-buffer-create gnus-backlog-buffer)
(buffer-disable-undo)
(setq buffer-read-only t)
(get-buffer gnus-backlog-buffer))))
(gnus-add-shutdown 'gnus-backlog-shutdown 'gnus)
(defun gnus-backlog-shutdown ()
"Clear all backlog variables and buffers."
(interactive)
(gnus-kill-buffer gnus-backlog-buffer)
(setq gnus-backlog-articles nil))
(defun gnus-backlog-enter-article (group number buffer)
(when (and (numberp number)
(not (gnus-virtual-group-p group)))
(let ((ident (format "%s:%d" group number))
b)
(unless (member 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.
(with-current-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)
(put-text-property b (1+ b) 'gnus-backlog ident)
(gnus-error 3 "Article %d is blank" number))))))))
(defun gnus-backlog-remove-oldest-article ()
(with-current-buffer (gnus-backlog-buffer)
(goto-char (point-min))
(unless (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
(delete 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)
(let ((ident (format "%s:%d" group number))
beg)
(when (member ident gnus-backlog-articles)
;; It was in the backlog.
(with-current-buffer (gnus-backlog-buffer)
(save-excursion
(let (buffer-read-only)
(goto-char (point-min))
(when (setq beg (gnus-text-property-search
'gnus-backlog ident))
;; Find the end (i. e., the beginning of the next article).
(goto-char
(next-single-property-change
(1+ beg) 'gnus-backlog (current-buffer) (point-max)))
(delete-region beg (point))
;; Return success.
t)))
(setq gnus-backlog-articles
(delete ident gnus-backlog-articles)))))))
(defun gnus-backlog-request-article (group number &optional buffer)
(when (and (numberp number)
(not (gnus-virtual-group-p group)))
(let ((ident (format "%s:%d" group number))
beg end)
(when (member ident gnus-backlog-articles)
;; It was in the backlog.
(with-current-buffer (gnus-backlog-buffer)
(if (not (setq beg (gnus-text-property-search
'gnus-backlog ident)))
;; It wasn't in the backlog after all.
(ignore
(setq gnus-backlog-articles
(delete 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)))))
(with-current-buffer (or buffer (current-buffer))
(let ((inhibit-read-only t))
(erase-buffer)
(insert-buffer-substring gnus-backlog-buffer beg end)))
t))))
(provide 'gnus-bcklg)
;;; gnus-bcklg.el ends here