lisp/gnus/gnus-dup.el

   1 ;;; gnus-dup.el --- suppression of duplicate articles in Gnus
   2 ;; Copyright (C) 1996, 1997, 1998, 1999, 2000
   3 ;;        Free Software Foundation, Inc.
   4
   5 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
   6 ;; Keywords: news
   7
   8 ;; This file is part of GNU Emacs.
   9
  10 ;; GNU Emacs is free software; you can redistribute it and/or modify
  11 ;; it under the terms of the GNU General Public License as published by
  12 ;; the Free Software Foundation; either version 2, or (at your option)
  13 ;; any later version.
  14
  15 ;; GNU Emacs is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;; GNU General Public License for more details.
  19
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  22 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  23 ;; Boston, MA 02111-1307, USA.
  24
  25 ;;; Commentary:
  26
  27 ;; This package tries to mark articles as read the second time the
  28 ;; user reads a copy.  This is useful if the server doesn't support
  29 ;; Xref properly, or if the user reads the same group from several
  30 ;; servers.
  31
  32 ;;; Code:
  33
  34 (eval-when-compile (require 'cl))
  35
  36 (require 'gnus)
  37 (require 'gnus-art)
  38
  39 (defgroup gnus-duplicate nil
  40   "Suppression of duplicate articles."
  41   :group 'gnus)
  42
  43 (defcustom gnus-save-duplicate-list nil
  44   "*If non-nil, save the duplicate list when shutting down Gnus.
  45 If nil, duplicate suppression will only work on duplicates
  46 seen in the same session."
  47   :group 'gnus-duplicate
  48   :type 'boolean)
  49
  50 (defcustom gnus-duplicate-list-length 10000
  51   "*The number of Message-IDs to keep in the duplicate suppression list."
  52   :group 'gnus-duplicate
  53   :type 'integer)
  54
  55 (defcustom gnus-duplicate-file (nnheader-concat gnus-directory "suppression")
  56   "*The name of the file to store the duplicate suppression list."
  57   :group 'gnus-duplicate
  58   :type 'file)
  59
  60 ;;; Internal variables
  61
  62 (defvar gnus-dup-list nil)
  63 (defvar gnus-dup-hashtb nil)
  64
  65 (defvar gnus-dup-list-dirty nil)
  66
  67 ;;;
  68 ;;; Starting and stopping
  69 ;;;
  70
  71 (gnus-add-shutdown 'gnus-dup-close 'gnus)
  72
  73 (defun gnus-dup-close ()
  74   "Possibly save the duplicate suppression list and shut down the subsystem."
  75   (gnus-dup-save)
  76   (setq gnus-dup-list nil
  77         gnus-dup-hashtb nil
  78         gnus-dup-list-dirty nil))
  79
  80 (defun gnus-dup-open ()
  81   "Possibly read the duplicate suppression list and start the subsystem."
  82   (if gnus-save-duplicate-list
  83       (gnus-dup-read)
  84     (setq gnus-dup-list nil))
  85   (setq gnus-dup-hashtb (gnus-make-hashtable gnus-duplicate-list-length))
  86   ;; Enter all Message-IDs into the hash table.
  87   (let ((list gnus-dup-list)
  88         (obarray gnus-dup-hashtb))
  89     (while list
  90       (intern (pop list)))))
  91
  92 (defun gnus-dup-read ()
  93   "Read the duplicate suppression list."
  94   (setq gnus-dup-list nil)
  95   (when (file-exists-p gnus-duplicate-file)
  96     (load gnus-duplicate-file t t t)))
  97
  98 (defun gnus-dup-save ()
  99   "Save the duplicate suppression list."
 100   (when (and gnus-save-duplicate-list
 101              gnus-dup-list-dirty)
 102     (with-temp-file gnus-duplicate-file
 103       (gnus-prin1 `(setq gnus-dup-list ',gnus-dup-list))))
 104   (setq gnus-dup-list-dirty nil))
 105
 106 ;;;
 107 ;;; Interface functions
 108 ;;;
 109
 110 (defun gnus-dup-enter-articles ()
 111   "Enter articles from the current group for future duplicate suppression."
 112   (unless gnus-dup-list
 113     (gnus-dup-open))
 114   (setq gnus-dup-list-dirty t)          ; mark list for saving
 115   (let ((data gnus-newsgroup-data)
 116         datum msgid)
 117     ;; Enter the Message-IDs of all read articles into the list
 118     ;; and hash table.
 119     (while (setq datum (pop data))
 120       (when (and (not (gnus-data-pseudo-p datum))
 121                  (> (gnus-data-number datum) 0)
 122                  (not (memq (gnus-data-number datum) gnus-newsgroup-unreads))
 123                  (not (= (gnus-data-mark datum) gnus-canceled-mark))
 124                  (setq msgid (mail-header-id (gnus-data-header datum)))
 125                  (not (nnheader-fake-message-id-p msgid))
 126                  (not (intern-soft msgid gnus-dup-hashtb)))
 127         (push msgid gnus-dup-list)
 128         (intern msgid gnus-dup-hashtb))))
 129   ;; Chop off excess Message-IDs from the list.
 130   (let ((end (nthcdr gnus-duplicate-list-length gnus-dup-list)))
 131     (when end
 132       (setcdr end nil))))
 133
 134 (defun gnus-dup-suppress-articles ()
 135   "Mark duplicate articles as read."
 136   (unless gnus-dup-list
 137     (gnus-dup-open))
 138   (gnus-message 6 "Suppressing duplicates...")
 139   (let ((headers gnus-newsgroup-headers)
 140         (auto (and gnus-newsgroup-auto-expire
 141                    (memq gnus-duplicate-mark gnus-auto-expirable-marks)))
 142         number header)
 143     (while (setq header (pop headers))
 144       (when (and (intern-soft (mail-header-id header) gnus-dup-hashtb)
 145                  (gnus-summary-article-unread-p (mail-header-number header)))
 146         (setq gnus-newsgroup-unreads
 147               (delq (setq number (mail-header-number header))
 148                     gnus-newsgroup-unreads))
 149         (if (not auto)
 150             (push (cons number gnus-duplicate-mark) gnus-newsgroup-reads)
 151           (push number gnus-newsgroup-expirable)
 152           (push (cons number gnus-expirable-mark) gnus-newsgroup-reads)))))
 153   (gnus-message 6 "Suppressing duplicates...done"))
 154
 155 (defun gnus-dup-unsuppress-article (article)
 156   "Stop suppression of ARTICLE."
 157   (let ((id (mail-header-id (gnus-data-header (gnus-data-find article)))))
 158     (when id
 159       (setq gnus-dup-list-dirty t)
 160       (setq gnus-dup-list (delete id gnus-dup-list))
 161       (unintern id gnus-dup-hashtb))))
 162
 163 (provide 'gnus-dup)
 164
 165 ;;; gnus-dup.el ends here