bug#49081: 28.0.50; [PATCH] Feature suggestion, Gnus summary mode sorting for extra headers

[Alex Bochannek]

Hello!

Since I was able to get the Newsgroups extra header working for
`nnvirtual' groups, I would like to not only limit, but also sort by the
extra headers.

Thanks!

        New Gnus Summary buffer sort options for extra headers

        * lisp/gnus/gnus-sum.el (gnus-article-sort-functions)
        (gnus-thread-sort-functions, gnus-subthread-sort-functions)
        (gnus-summary-mode-map, gnus-summary-make-menu-bar)
        (gnus-article-sort-by-newsgroups)
        (gnus-summary-sort-by-newsgroups, gnus-summary-sort-by-extra):
        Sort by Newsgroups extra header. Prompt for header name for other
        extra headers.

        * doc/misc/gnus.texi (Summary Sorting): Document new sort functions

        * etc/NEWS: New Gnus Summary buffer sort feature

diff --git a/doc/misc/gnus.texi b/doc/misc/gnus.texi
index b63947c044..c9b5b2d9ff 100644
--- a/doc/misc/gnus.texi
+++ b/doc/misc/gnus.texi
@@ -4126,6 +4126,8 @@ Topic Variables
 Level.
 @item g
 Number of groups in the topic.
+@item G
+Number of groups in the topic and all its subtopics.
 @item a
 Number of unread articles in the topic.
 @item A
@@ -7525,6 +7527,7 @@ Sorting the Summary Buffer
 @findex gnus-thread-sort-by-author
 @findex gnus-thread-sort-by-recipient
 @findex gnus-thread-sort-by-number
+@findex gnus-thread-sort-by-newsgroups
 @findex gnus-thread-sort-by-random
 @vindex gnus-thread-sort-functions
 @findex gnus-thread-sort-by-most-recent-number
@@ -7542,6 +7545,7 @@ Sorting the Summary Buffer
 @code{gnus-thread-sort-by-score},
 @code{gnus-thread-sort-by-most-recent-number},
 @code{gnus-thread-sort-by-most-recent-date},
+@code{gnus-thread-sort-by-newsgroups} and
 @code{gnus-thread-sort-by-random} and
 @code{gnus-thread-sort-by-total-score}.
 
@@ -7603,6 +7607,7 @@ Sorting the Summary Buffer
 @findex gnus-article-sort-by-score
 @findex gnus-article-sort-by-subject
 @findex gnus-article-sort-by-author
+@findex gnus-article-sort-by-newsgroups
 @findex gnus-article-sort-by-random
 @findex gnus-article-sort-by-number
 @findex gnus-article-sort-by-most-recent-number
@@ -7614,8 +7619,8 @@ Sorting the Summary Buffer
 predicate functions are @code{gnus-article-sort-by-number},
 @code{gnus-article-sort-by-author},
 @code{gnus-article-sort-by-subject}, @code{gnus-article-sort-by-date},
-@code{gnus-article-sort-by-random}, and
-@code{gnus-article-sort-by-score}.
+@code{gnus-article-sort-by-newsgroups}, @code{gnus-article-sort-by-random},
+and @code{gnus-article-sort-by-score}.
 
 If you want to sort an unthreaded summary display by subject, you could
 say something like:
@@ -10403,6 +10408,17 @@ Summary Sorting
 @findex gnus-summary-sort-by-score
 Sort by score (@code{gnus-summary-sort-by-score}).
 
+@item C-c C-s C-u
+@kindex C-c C-s C-u @r{(Summary)}
+@findex gnus-summary-sort-by-newsgroups
+Sort by newsgroups (@code{gnus-summary-sort-by-newsgroups}).
+
+@item C-c C-s C-x
+@kindex C-c C-s C-x @r{(Summary)}
+@findex gnus-summary-sort-by-extra
+Prompts for extra header to sort by (@code{gnus-summary-sort-by-extra}).
+An error will be raised if no sort functions for the header are defined.
+
 @item C-c C-s C-r
 @kindex C-c C-s C-r @r{(Summary)}
 @findex gnus-summary-sort-by-random
diff --git a/etc/NEWS b/etc/NEWS
index da1372baf4..b5c1fa79ff 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -897,6 +897,12 @@ String or list of strings specifying switches for Git log 
under VC.
 
 ** Gnus
 
++++
+*** New Summary buffer sort options for extra headers.
+The extra header sort option ('C-c C-s C-x') prompts for a header
+and fails if no sort function has been defined. Sorting by
+Newsgroups ('C-c C-s C-u') has been pre-defined.
+
 +++
 *** The '#' command in the Group and Summary buffer now toggles,
 instead of sets, the process mark.
diff --git a/lisp/gnus/gnus-sum.el b/lisp/gnus/gnus-sum.el
index bcd76dda29..7c5d3833f1 100644
--- a/lisp/gnus/gnus-sum.el
+++ b/lisp/gnus/gnus-sum.el
@@ -879,8 +879,9 @@ gnus-article-sort-functions
 
 Ready-made functions include `gnus-article-sort-by-number',
 `gnus-article-sort-by-author', `gnus-article-sort-by-subject',
-`gnus-article-sort-by-date', `gnus-article-sort-by-random'
-and `gnus-article-sort-by-score'.
+`gnus-article-sort-by-date', `gnus-article-sort-by-score',
+`gnus-article-sort-by-rsv', `gnus-article-sort-by-newsgroups',
+and `gnus-article-sort-by-random'.
 
 When threading is turned on, the variable `gnus-thread-sort-functions'
 controls how articles are sorted."
@@ -892,6 +893,7 @@ gnus-article-sort-functions
                           (function-item gnus-article-sort-by-date)
                           (function-item gnus-article-sort-by-score)
                           (function-item gnus-article-sort-by-rsv)
+                          (function-item gnus-article-sort-by-newsgroups)
                           (function-item gnus-article-sort-by-random)
                           (function :tag "other"))
                   (boolean :tag "Reverse order"))))
@@ -916,8 +918,8 @@ gnus-thread-sort-functions
 `gnus-thread-sort-by-author', `gnus-thread-sort-by-recipient'
 `gnus-thread-sort-by-subject', `gnus-thread-sort-by-date',
 `gnus-thread-sort-by-score', `gnus-thread-sort-by-most-recent-number',
-`gnus-thread-sort-by-most-recent-date', `gnus-thread-sort-by-random',
-and `gnus-thread-sort-by-total-score' (see
+`gnus-thread-sort-by-most-recent-date', `gnus-thread-sort-by-newsgroups',
+`gnus-thread-sort-by-random', and `gnus-thread-sort-by-total-score' (see
 `gnus-thread-score-function').
 
 When threading is turned off, the variable
@@ -938,6 +940,7 @@ gnus-thread-sort-functions
                    (function-item gnus-thread-sort-by-rsv)
                    (function-item gnus-thread-sort-by-most-recent-number)
                    (function-item gnus-thread-sort-by-most-recent-date)
+                   (function-item gnus-thread-sort-by-newsgroups)
                    (function-item gnus-thread-sort-by-random)
                    (function-item gnus-thread-sort-by-total-score)
                    (function :tag "other"))
@@ -961,6 +964,7 @@ gnus-subthread-sort-functions
                    (function-item gnus-thread-sort-by-score)
                    (function-item gnus-thread-sort-by-most-recent-number)
                    (function-item gnus-thread-sort-by-most-recent-date)
+                    (function-item gnus-thread-sort-by-newsgroups)
                    (function-item gnus-thread-sort-by-random)
                    (function-item gnus-thread-sort-by-total-score)
                    (function :tag "other"))
@@ -1976,6 +1980,8 @@ gnus-summary-mode-map
   "\C-c\C-s\C-i" gnus-summary-sort-by-score
   "\C-c\C-s\C-o" gnus-summary-sort-by-original
   "\C-c\C-s\C-r" gnus-summary-sort-by-random
+  "\C-c\C-s\C-u" gnus-summary-sort-by-newsgroups
+  "\C-c\C-s\C-x" gnus-summary-sort-by-extra
   "=" gnus-summary-expand-window
   "\C-x\C-s" gnus-summary-reselect-current-group
   "\M-g" gnus-summary-rescan-group
@@ -2831,6 +2837,8 @@ gnus-summary-make-menu-bar
         ["Sort by lines" gnus-summary-sort-by-lines t]
         ["Sort by characters" gnus-summary-sort-by-chars t]
         ["Sort by marks" gnus-summary-sort-by-marks t]
+        ["Sort by newsgroup" gnus-summary-sort-by-newsgroups t]
+        ["Sort by extra" gnus-summary-sort-by-extra t]
         ["Randomize" gnus-summary-sort-by-random t]
         ["Original sort" gnus-summary-sort-by-original t])
        ("Help"
@@ -5180,6 +5188,24 @@ gnus-thread-sort-by-most-recent-date
   "Sort threads such that the thread with the most recently dated article 
comes first."
   (> (gnus-thread-latest-date h1) (gnus-thread-latest-date h2)))
 
+(defun gnus-article-sort-by-newsgroups (h1 h2)
+  "Sort articles by newsgroups."
+  (gnus-string<
+   (let ((extract (funcall
+                  gnus-extract-address-components
+                  (or (cdr (assq 'Newsgroups (mail-header-extra h1))) ""))))
+     (or (car extract) (cadr extract)))
+   (let ((extract (funcall
+                  gnus-extract-address-components
+                  (or (cdr (assq 'Newsgroups (mail-header-extra h2))) ""))))
+     (or (car extract) (cadr extract)))))
+
+(defun gnus-thread-sort-by-newsgroups (h1 h2)
+  "Sort threads by root newsgroups."
+  (gnus-article-sort-by-newsgroups
+   (gnus-thread-header h1) (gnus-thread-header h2)))
+
+
 ; Since this is called not only to sort the top-level threads, but
 ; also in recursive sorts to order the articles within a thread, each
 ; article will be processed many times.  Thus it speeds things up
@@ -12122,6 +12148,12 @@ gnus-summary-sort-by-marks
   (interactive "P" gnus-summary-mode)
   (gnus-summary-sort 'marks reverse))
 
+(defun gnus-summary-sort-by-newsgroups (&optional reverse)
+  "Sort the summary buffer by newsgroups alphabetically.
+Argument REVERSE means reverse order."
+  (interactive "P" gnus-summary-mode)
+  (gnus-summary-sort 'newsgroups reverse))
+
 (defun gnus-summary-sort-by-original (&optional _reverse)
   "Sort the summary buffer using the default sorting method.
 Argument REVERSE means reverse order."
@@ -12133,6 +12165,24 @@ gnus-summary-sort-by-original
     ;; Hide subthreads if needed.
     (gnus-summary-maybe-hide-threads)))
 
+(defun gnus-summary-sort-by-extra (&optional reverse)
+  "Sort the summary buffer using an extra header.
+Argument REVERSE means reverse order."
+  (interactive "P" gnus-summary-mode)
+  (let* ((extra-header
+         (gnus-completing-read "Sort by extra header"
+          (mapcar #'symbol-name gnus-extra-headers)
+          t nil nil
+          (symbol-name
+           (car gnus-extra-headers))))
+       (header (downcase extra-header)))
+    (if (and (fboundp (intern
+                      (format "gnus-thread-sort-by-%s" header)))
+            (fboundp
+             (intern (format "gnus-article-sort-by-%s" header))))
+       (gnus-summary-sort header reverse)
+      (error "No sort function defined for header: %s" extra-header))))
+
 (defun gnus-summary-sort (predicate reverse)
   "Sort summary buffer by PREDICATE.  REVERSE means reverse order."
   (let* ((current (gnus-summary-article-number))

-- 
Alex.