Merge changes made in Emacs trunk

[gnus] / lisp / gnus-sum.el

;;; gnus-sum.el --- summary mode commands for Gnus

;; Copyright (C) 1996-2012 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:

;; For Emacs <22.2 and XEmacs.
(eval-and-compile
  (unless (fboundp 'declare-function) (defmacro declare-function (&rest r))))
(eval-when-compile
  (require 'cl))
(eval-when-compile
  (when (featurep 'xemacs)
    (require 'easy-mmode))) ; for `define-minor-mode'

(defvar tool-bar-mode)
(defvar gnus-tmp-header)

(require 'gnus)
(require 'gnus-group)
(require 'gnus-spec)
(require 'gnus-range)
(require 'gnus-int)
(require 'gnus-undo)
(require 'gnus-util)
(require 'gmm-utils)
(require 'mm-decode)
(require 'nnoo)

(autoload 'gnus-summary-limit-include-cached "gnus-cache" nil t)
(autoload 'gnus-cache-write-active "gnus-cache")
(autoload 'gnus-mailing-list-insinuate "gnus-ml" nil t)
(autoload 'turn-on-gnus-mailing-list-mode "gnus-ml" nil t)
(autoload 'gnus-pick-line-number "gnus-salt" nil t)
(autoload 'mm-uu-dissect "mm-uu")
(autoload 'gnus-article-outlook-deuglify-article "deuglify"
  "Deuglify broken Outlook (Express) articles and redisplay."
  t)
(autoload 'gnus-article-outlook-unwrap-lines "deuglify" nil t)
(autoload 'gnus-article-outlook-repair-attribution "deuglify" nil t)
(autoload 'gnus-article-outlook-rearrange-citation "deuglify" nil t)
(autoload 'nnir-article-rsv "nnir" nil nil 'macro)
(autoload 'nnir-article-group "nnir" nil nil 'macro)

(defcustom gnus-kill-summary-on-exit t
  "*If non-nil, kill the summary buffer when you exit from it.
If nil, the summary will become a \"*Dead Summary*\" buffer, and
it will be killed sometime later."
  :group 'gnus-summary-exit
  :type 'boolean)

(defcustom gnus-summary-next-group-on-exit t
  "If non-nil, go to the next unread newsgroup on summary exit.
See `gnus-group-goto-unread'."
  :link '(custom-manual "(gnus)Group Maneuvering")
  :group 'gnus-summary-exit
  :version "23.1" ;; No Gnus
  :type 'boolean)

(defcustom gnus-summary-stop-at-end-of-message nil
  "If non-nil, don't select the next message when using `SPC'."
  :link '(custom-manual "(gnus)Group Maneuvering")
  :group 'gnus-summary-maneuvering
  :version "24.1"
  :type 'boolean)

(defcustom gnus-fetch-old-headers nil
  "*Non-nil means that Gnus will try to build threads by grabbing old headers.
If an unread article in the group refers to an older, already
read (or just marked as read) article, the old article will not
normally be displayed in the Summary buffer.  If this variable is
t, Gnus will attempt to grab the headers to the old articles, and
thereby build complete threads.  If it has the value `some', all
old headers will be fetched but only enough headers to connect
otherwise loose threads will be displayed.  This variable can
also be a number.  In that case, no more than that number of old
headers will be fetched.  If it has the value `invisible', all
old headers will be fetched, but none will be displayed.

The server has to support NOV for any of this to work.

This feature can seriously impact performance it ignores all
locally cached header entries.  Setting it to t for groups for a
server that doesn't expire articles (such as news.gmane.org),
leads to very slow summary generation."
  :group 'gnus-thread
  :type '(choice (const :tag "off" nil)
                 (const :tag "on" t)
                 (const some)
                 (const invisible)
                 number
                 (sexp :menu-tag "other" t)))

(defcustom gnus-refer-thread-limit 500
  "*The number of old headers to fetch when doing \\<gnus-summary-mode-map>\\[gnus-summary-refer-thread].
If t, fetch all the available old headers."
  :group 'gnus-thread
  :type '(choice number
                 (sexp :menu-tag "other" t)))

(defcustom gnus-refer-thread-use-nnir nil
  "*Use nnir to search an entire server when referring threads. A
nil value will only search for thread-related articles in the
current group."
  :version "24.1"
  :group 'gnus-thread
  :type 'boolean)

(defcustom gnus-summary-make-false-root 'adopt
  "*nil means that Gnus won't gather loose threads.
If the root of a thread has expired or been read in a previous
session, the information necessary to build a complete thread has been
lost.  Instead of having many small sub-threads from this original thread
scattered all over the summary buffer, Gnus can gather them.

If non-nil, Gnus will try to gather all loose sub-threads from an
original thread into one large thread.

If this variable is non-nil, it should be one of `none', `adopt',
`dummy' or `empty'.

If this variable is `none', Gnus will not make a false root, but just
present the sub-threads after another.
If this variable is `dummy', Gnus will create a dummy root that will
have all the sub-threads as children.
If this variable is `adopt', Gnus will make one of the \"children\"
the parent and mark all the step-children as such.
If this variable is `empty', the \"children\" are printed with empty
subject fields.  (Or rather, they will be printed with a string
given by the `gnus-summary-same-subject' variable.)"
  :group 'gnus-thread
  :type '(choice (const :tag "off" nil)
                 (const none)
                 (const dummy)
                 (const adopt)
                 (const empty)))

(defcustom gnus-summary-make-false-root-always nil
  "Always make a false dummy root."
  :version "22.1"
  :group 'gnus-thread
  :type 'boolean)

(defcustom gnus-summary-gather-exclude-subject "^ *$\\|^(none)$"
  "*A regexp to match subjects to be excluded from loose thread gathering.
As loose thread gathering is done on subjects only, that means that
there can be many false gatherings performed.  By rooting out certain
common subjects, gathering might become saner."
  :group 'gnus-thread
  :type 'regexp)

(defcustom gnus-summary-gather-subject-limit nil
  "*Maximum length of subject comparisons when gathering loose threads.
Use nil to compare full subjects.  Setting this variable to a low
number will help gather threads that have been corrupted by
newsreaders chopping off subject lines, but it might also mean that
unrelated articles that have subject that happen to begin with the
same few characters will be incorrectly gathered.

If this variable is `fuzzy', Gnus will use a fuzzy algorithm when
comparing subjects."
  :group 'gnus-thread
  :type '(choice (const :tag "off" nil)
                 (const fuzzy)
                 (sexp :menu-tag "on" t)))

(defcustom gnus-simplify-subject-functions nil
  "List of functions taking a string argument that simplify subjects.
The functions are applied recursively.

Useful functions to put in this list include:
`gnus-simplify-subject-re', `gnus-simplify-subject-fuzzy',
`gnus-simplify-whitespace', and `gnus-simplify-all-whitespace'."
  :group 'gnus-thread
  :type '(repeat function))

(defcustom gnus-simplify-ignored-prefixes nil
  "*Remove matches for this regexp from subject lines when simplifying fuzzily."
  :group 'gnus-thread
  :type '(choice (const :tag "off" nil)
                 regexp))

(defcustom gnus-build-sparse-threads nil
  "*If non-nil, fill in the gaps in threads.
If `some', only fill in the gaps that are needed to tie loose threads
together.  If `more', fill in all leaf nodes that Gnus can find.  If
non-nil and non-`some', fill in all gaps that Gnus manages to guess."
  :group 'gnus-thread
  :type '(choice (const :tag "off" nil)
                 (const some)
                 (const more)
                 (sexp :menu-tag "all" t)))

(defcustom gnus-summary-thread-gathering-function
  'gnus-gather-threads-by-subject
  "*Function used for gathering loose threads.
There are two pre-defined functions: `gnus-gather-threads-by-subject',
which only takes Subjects into consideration; and
`gnus-gather-threads-by-references', which compared the References
headers of the articles to find matches."
  :group 'gnus-thread
  :type '(radio (function-item gnus-gather-threads-by-subject)
                (function-item gnus-gather-threads-by-references)
                (function :tag "other")))

(defcustom gnus-summary-same-subject ""
  "*String indicating that the current article has the same subject as the previous.
This variable will only be used if the value of
`gnus-summary-make-false-root' is `empty'."
  :group 'gnus-summary-format
  :type 'string)

(defcustom gnus-summary-goto-unread nil
  "*If t, many commands will go to the next unread article.
This applies to marking commands as well as other commands that
\"naturally\" select the next article, like, for instance, `SPC' at
the end of an article.

If nil, the marking commands do NOT go to the next unread article
\(they go to the next article instead).  If `never', commands that
usually go to the next unread article, will go to the next article,
whether it is read or not."
  :version "24.1"
  :group 'gnus-summary-marks
  :link '(custom-manual "(gnus)Setting Marks")
  :type '(choice (const :tag "off" nil)
                 (const never)
                 (sexp :menu-tag "on" t)))

(defcustom gnus-summary-default-score 0
  "*Default article score level.
All scores generated by the score files will be added to this score.
If this variable is nil, scoring will be disabled."
  :group 'gnus-score-default
  :type '(choice (const :tag "disable")
                 integer))

(defcustom gnus-summary-default-high-score 0
  "*Default threshold for a high scored article.
An article will be highlighted as high scored if its score is greater
than this score."
  :version "22.1"
  :group 'gnus-score-default
  :type 'integer)

(defcustom gnus-summary-default-low-score 0
  "*Default threshold for a low scored article.
An article will be highlighted as low scored if its score is smaller
than this score."
  :version "22.1"
  :group 'gnus-score-default
  :type 'integer)

(defcustom gnus-summary-zcore-fuzz 0
  "*Fuzziness factor for the zcore in the summary buffer.
Articles with scores closer than this to `gnus-summary-default-score'
will not be marked."
  :group 'gnus-summary-format
  :type 'integer)

(defcustom gnus-simplify-subject-fuzzy-regexp nil
  "*Strings to be removed when doing fuzzy matches.
This can either be a regular expression or list of regular expressions
that will be removed from subject strings if fuzzy subject
simplification is selected."
  :group 'gnus-thread
  :type '(repeat regexp))

(defcustom gnus-show-threads t
  "*If non-nil, display threads in summary mode."
  :group 'gnus-thread
  :type 'boolean)

(defcustom gnus-thread-hide-subtree nil
  "*If non-nil, hide all threads initially.
This can be a predicate specifier which says which threads to hide.
If threads are hidden, you have to run the command
`gnus-summary-show-thread' by hand or select an article."
  :group 'gnus-thread
  :type '(radio (sexp :format "Non-nil\n"
                      :match (lambda (widget value)
                               (not (or (consp value) (functionp value))))
                      :value t)
                (const nil)
                (sexp :tag "Predicate specifier")))

(defcustom gnus-thread-hide-killed t
  "*If non-nil, hide killed threads automatically."
  :group 'gnus-thread
  :type 'boolean)

(defcustom gnus-thread-ignore-subject t
  "*If non-nil, which is the default, ignore subjects and do all threading based on the Reference header.
If nil, articles that have different subjects from their parents will
start separate threads."
  :group 'gnus-thread
  :type 'boolean)

(defcustom gnus-thread-operation-ignore-subject t
  "*If non-nil, subjects will be ignored when doing thread commands.
This affects commands like `gnus-summary-kill-thread' and
`gnus-summary-lower-thread'.

If this variable is nil, articles in the same thread with different
subjects will not be included in the operation in question.  If this
variable is `fuzzy', only articles that have subjects that are fuzzily
equal will be included."
  :group 'gnus-thread
  :type '(choice (const :tag "off" nil)
                 (const fuzzy)
                 (sexp :tag "on" t)))

(defcustom gnus-thread-indent-level 4
  "*Number that says how much each sub-thread should be indented."
  :group 'gnus-thread
  :type 'integer)

(defcustom gnus-auto-extend-newsgroup t
  "*If non-nil, extend newsgroup forward and backward when requested."
  :group 'gnus-summary-choose
  :type 'boolean)

(defcustom gnus-auto-select-first t
  "If non-nil, select an article on group entry.
An article is selected automatically when entering a group
e.g. with \\<gnus-group-mode-map>\\[gnus-group-read-group], or via `gnus-summary-next-page' or
`gnus-summary-catchup-and-goto-next-group'.

Which article is selected is controlled by the variable
`gnus-auto-select-subject'.

If you want to prevent automatic selection of articles in some
newsgroups, set the variable to nil in `gnus-select-group-hook'."
  ;; Commands include...
  ;; \\<gnus-group-mode-map>\\[gnus-group-read-group]
  ;; \\<gnus-summary-mode-map>\\[gnus-summary-next-page]
  ;; \\<gnus-summary-mode-map>\\[gnus-summary-catchup-and-goto-next-group]
  :group 'gnus-group-select
  :type '(choice (const :tag "none" nil)
                 (sexp :menu-tag "first" t)))

(defcustom gnus-auto-select-subject 'unseen-or-unread
  "*Says what subject to place under point when entering a group.

This variable can either be the symbols `first' (place point on the
first subject), `unread' (place point on the subject line of the first
unread article), `best' (place point on the subject line of the
highest-scored article), `unseen' (place point on the subject line of
the first unseen article), `unseen-or-unread' (place point on the subject
line of the first unseen article or, if all articles have been seen, on the
subject line of the first unread article), or a function to be called to
place point on some subject line."
  :version "24.1"
  :group 'gnus-group-select
  :type '(choice (const best)
                 (const unread)
                 (const first)
                 (const unseen)
                 (const unseen-or-unread)
                 (function :tag "Function to call")))

(defcustom gnus-auto-select-next t
  "*If non-nil, offer to go to the next group from the end of the previous.
If the value is t and the next newsgroup is empty, Gnus will exit
summary mode and go back to group mode.  If the value is neither nil
nor t, Gnus will select the following unread newsgroup.  In
particular, if the value is the symbol `quietly', the next unread
newsgroup will be selected without any confirmation, and if it is
`almost-quietly', the next group will be selected without any
confirmation if you are located on the last article in the group.
Finally, if this variable is `slightly-quietly', the `\\<gnus-summary-mode-map>\\[gnus-summary-catchup-and-goto-next-group]' command
will go to the next group without confirmation."
  :group 'gnus-summary-maneuvering
  :type '(choice (const :tag "off" nil)
                 (const quietly)
                 (const almost-quietly)
                 (const slightly-quietly)
                 (sexp :menu-tag "on" t)))

(defcustom gnus-auto-select-same nil
  "*If non-nil, select the next article with the same subject.
If there are no more articles with the same subject, go to
the first unread article."
  :group 'gnus-summary-maneuvering
  :type 'boolean)

(defcustom gnus-auto-select-on-ephemeral-exit 'next-noselect
  "What article should be selected after exiting an ephemeral group.
Valid values include:

`next'
  Select the next article.
`next-unread'
  Select the next unread article.
`next-noselect'
  Move the cursor to the next article.  This is the default.
`next-unread-noselect'
  Move the cursor to the next unread article.

If it has any other value or there is no next (unread) article, the
article selected before entering to the ephemeral group will appear."
  :version "23.1" ;; No Gnus
  :group 'gnus-summary-maneuvering
  :type '(choice :format "%{%t%}:\n %[Value Menu%] %v"
                 (const next) (const next-unread)
                 (const next-noselect) (const next-unread-noselect)
                 (sexp :tag "other" :value nil)))

(defcustom gnus-auto-goto-ignores 'unfetched
  "*Says how to handle unfetched articles when maneuvering.

This variable can either be the symbols nil (maneuver to any
article), `undownloaded' (maneuvering while unplugged ignores articles
that have not been fetched), `always-undownloaded' (maneuvering always
ignores articles that have not been fetched), `unfetched' (maneuvering
ignores articles whose headers have not been fetched).

NOTE: The list of unfetched articles will always be nil when plugged
and, when unplugged, a subset of the undownloaded article list."
  :version "22.1"
  :group 'gnus-summary-maneuvering
  :type '(choice (const :tag "None" nil)
                 (const :tag "Undownloaded when unplugged" undownloaded)
                 (const :tag "Undownloaded" always-undownloaded)
                 (const :tag "Unfetched" unfetched)))

(defcustom gnus-summary-check-current nil
  "*If non-nil, consider the current article when moving.
The \"unread\" movement commands will stay on the same line if the
current article is unread."
  :group 'gnus-summary-maneuvering
  :type 'boolean)

(defcustom gnus-auto-center-summary 
  (max (or (bound-and-true-p scroll-margin) 0) 2)
  "*If non-nil, always center the current summary buffer.
In particular, if `vertical' do only vertical recentering.  If non-nil
and non-`vertical', do both horizontal and vertical recentering."
  :group 'gnus-summary-maneuvering
  :type '(choice (const :tag "none" nil)
                 (const vertical)
                 (integer :tag "height")
                 (sexp :menu-tag "both" t)))

(defcustom gnus-auto-center-group t
  "If non-nil, always center the group buffer."
  :group 'gnus-summary-maneuvering
  :type 'boolean)

(defcustom gnus-show-all-headers nil
  "*If non-nil, don't hide any headers."
  :group 'gnus-article-hiding
  :group 'gnus-article-headers
  :type 'boolean)

(defcustom gnus-summary-ignore-duplicates nil
  "*If non-nil, ignore articles with identical Message-ID headers."
  :group 'gnus-summary
  :type 'boolean)

(defcustom gnus-single-article-buffer nil
  "*If non-nil, display all articles in the same buffer.
If nil, each group will get its own article buffer."
  :version "24.1"
  :group 'gnus-article-various
  :type 'boolean)

(defcustom gnus-widen-article-window nil
  "If non-nil, selecting the article buffer will display only the article buffer."
  :version "24.1"
  :group 'gnus-article-various
  :type 'boolean)

(defcustom gnus-break-pages t
  "*If non-nil, do page breaking on articles.
The page delimiter is specified by the `gnus-page-delimiter'
variable."
  :group 'gnus-article-various
  :type 'boolean)

(defcustom gnus-move-split-methods nil
  "*Variable used to suggest where articles are to be moved to.
It uses the same syntax as the `gnus-split-methods' variable.
However, whereas `gnus-split-methods' specifies file names as targets,
this variable specifies group names."
  :group 'gnus-summary-mail
  :type '(repeat (choice (list :value (fun) function)
                         (cons :value ("" "") regexp (repeat string))
                         (sexp :value nil))))

(defcustom gnus-move-group-prefix-function 'gnus-group-real-prefix
  "Function used to compute default prefix for article move/copy/etc prompts.
The function should take one argument, a group name, and return a