lisp/gnus-topic.el

   1 ;;; gnus-topic.el --- a folding minor mode for Gnus group buffers
   2
   3 ;; Copyright (C) 1995-2016 Free Software Foundation, Inc.
   4
   5 ;; Author: Ilja Weis <kult@uni-paderborn.de>
   6 ;;      Lars Magne Ingebrigtsen <larsi@gnus.org>
   7 ;; Keywords: news
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software: you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation, either version 3 of the License, or
  14 ;; (at your option) any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  23
  24 ;;; Commentary:
  25
  26 ;;; Code:
  27
  28 (eval-when-compile (require 'cl))
  29
  30 (require 'gnus)
  31 (require 'gnus-group)
  32 (require 'gnus-start)
  33 (require 'gnus-util)
  34
  35 (defgroup gnus-topic nil
  36   "Group topics."
  37   :group 'gnus-group)
  38
  39 (defvar gnus-topic-mode nil
  40   "Minor mode for Gnus group buffers.")
  41
  42 (defcustom gnus-topic-mode-hook nil
  43   "Hook run in topic mode buffers."
  44   :type 'hook
  45   :group 'gnus-topic)
  46
  47 (when (featurep 'xemacs)
  48   (add-hook 'gnus-topic-mode-hook 'gnus-xmas-topic-menu-add))
  49
  50 (defcustom gnus-topic-line-format "%i[ %(%{%n%}%) -- %A ]%v\n"
  51   "Format of topic lines.
  52 It works along the same lines as a normal formatting string,
  53 with some simple extensions.
  54
  55 %i  Indentation based on topic level.
  56 %n  Topic name.
  57 %v  Nothing if the topic is visible, \"...\" otherwise.
  58 %g  Number of groups in the topic.
  59 %a  Number of unread articles in the groups in the topic.
  60 %A  Number of unread articles in the groups in the topic and its subtopics.
  61
  62 General format specifiers can also be used.
  63 See Info node `(gnus)Formatting Variables'."
  64   :link '(custom-manual "(gnus)Formatting Variables")
  65   :type 'string
  66   :group 'gnus-topic)
  67
  68 (defcustom gnus-topic-indent-level 2
  69   "*How much each subtopic should be indented."
  70   :type 'integer
  71   :group 'gnus-topic)
  72
  73 (defcustom gnus-topic-display-empty-topics t
  74   "*If non-nil, display the topic lines even of topics that have no unread articles."
  75   :type 'boolean
  76   :group 'gnus-topic)
  77
  78 ;; Internal variables.
  79
  80 (defvar gnus-topic-active-topology nil)
  81 (defvar gnus-topic-active-alist nil)
  82 (defvar gnus-topic-unreads nil)
  83
  84 (defvar gnus-topology-checked-p nil
  85   "Whether the topology has been checked in this session.")
  86
  87 (defvar gnus-topic-killed-topics nil)
  88 (defvar gnus-topic-inhibit-change-level nil)
  89
  90 (defconst gnus-topic-line-format-alist
  91   `((?n name ?s)
  92     (?v visible ?s)
  93     (?i indentation ?s)
  94     (?g number-of-groups ?d)
  95     (?a (gnus-topic-articles-in-topic entries) ?d)
  96     (?A total-number-of-articles ?d)
  97     (?l level ?d)))
  98
  99 (defvar gnus-topic-line-format-spec nil)
 100
 101 ;;; Utility functions
 102
 103 (defun gnus-group-topic-name ()
 104   "The name of the topic on the current line."
 105   (let ((topic (get-text-property (point-at-bol) 'gnus-topic)))
 106     (and topic (symbol-name topic))))
 107
 108 (defun gnus-group-topic-level ()
 109   "The level of the topic on the current line."
 110   (get-text-property (point-at-bol) 'gnus-topic-level))
 111
 112 (defun gnus-group-topic-unread ()
 113   "The number of unread articles in topic on the current line."
 114   (get-text-property (point-at-bol) 'gnus-topic-unread))
 115
 116 (defun gnus-topic-unread (topic)
 117   "Return the number of unread articles in TOPIC."
 118   (or (cdr (assoc topic gnus-topic-unreads))
 119       0))
 120
 121 (defun gnus-group-topic-p ()
 122   "Return non-nil if the current line is a topic."
 123   (gnus-group-topic-name))
 124
 125 (defun gnus-topic-visible-p ()
 126   "Return non-nil if the current topic is visible."
 127   (get-text-property (point-at-bol) 'gnus-topic-visible))
 128
 129 (defun gnus-topic-articles-in-topic (entries)
 130   (let ((total 0)
 131         number)
 132     (while entries
 133       (when (numberp (setq number (car (pop entries))))
 134         (incf total number)))
 135     total))
 136
 137 (defun gnus-group-topic (group)
 138   "Return the topic GROUP is a member of."
 139   (let ((alist gnus-topic-alist)
 140         out)
 141     (while alist
 142       (when (member group (cdar alist))
 143         (setq out (caar alist)
 144               alist nil))
 145       (setq alist (cdr alist)))
 146     out))
 147
 148 (defun gnus-topic-goto-topic (topic)
 149   (when topic
 150     (gnus-goto-char (text-property-any (point-min) (point-max)
 151                                        'gnus-topic (intern topic)))))
 152
 153 (defun gnus-topic-jump-to-topic (topic)
 154   "Go to TOPIC."
 155   (interactive
 156    (list (gnus-completing-read "Go to topic" (gnus-topic-list) t)))
 157   (let ((inhibit-read-only t))
 158     (dolist (topic (gnus-current-topics topic))
 159       (unless (gnus-topic-goto-topic topic)
 160         (gnus-topic-goto-missing-topic topic)
 161         (gnus-topic-display-missing-topic topic))))
 162   (gnus-topic-goto-topic topic))
 163
 164 (defun gnus-current-topic ()
 165   "Return the name of the current topic."
 166   (let ((result
 167          (or (get-text-property (point) 'gnus-topic)
 168              (save-excursion
 169                (and (gnus-goto-char (previous-single-property-change
 170                                      (point) 'gnus-topic))
 171                     (get-text-property (max (1- (point)) (point-min))
 172                                        'gnus-topic))))))
 173     (when result
 174       (symbol-name result))))
 175
 176 (defun gnus-current-topics (&optional topic)
 177   "Return a list of all current topics, lowest in hierarchy first.
 178 If TOPIC, start with that topic."
 179   (let ((topic (or topic (gnus-current-topic)))
 180         topics)
 181     (while topic
 182       (push topic topics)
 183       (setq topic (gnus-topic-parent-topic topic)))
 184     (nreverse topics)))
 185
 186 (defun gnus-group-active-topic-p ()
 187   "Say whether the current topic comes from the active topics."
 188   (get-text-property (point-at-bol) 'gnus-active))
 189
 190 (defun gnus-topic-find-groups (topic &optional level all lowest recursive)
 191   "Return entries for all visible groups in TOPIC.
 192 If RECURSIVE is t, return groups in its subtopics too."
 193   (let ((groups (cdr (assoc topic gnus-topic-alist)))
 194         info clevel unread group params visible-groups entry active)
 195     (setq lowest (or lowest 1))
 196     (setq level (or level gnus-level-unsubscribed))
 197     ;; We go through the newsrc to look for matches.
 198     (while groups
 199       (when (setq group (pop groups))
 200         (setq entry (gnus-group-entry group)
 201               info (nth 2 entry)
 202               params (gnus-info-params info)
 203               active (gnus-active group)
 204               unread (or (car entry)
 205                          (and (not (equal group "dummy.group"))
 206                               active
 207                               (- (1+ (cdr active)) (car active))))
 208               clevel (or (gnus-info-level info)
 209                          (if (member group gnus-zombie-list)
 210                              gnus-level-zombie gnus-level-killed))))
 211       (and
 212        info                             ; nil means that the group is dead.
 213        (<= clevel level)
 214        (>= clevel lowest)               ; Is inside the level we want.
 215        (or all
 216            (if (or (eq unread t)
 217                    (eq unread nil))
 218                gnus-group-list-inactive-groups
 219              (> unread 0))
 220            (and gnus-list-groups-with-ticked-articles
 221                 (cdr (assq 'tick (gnus-info-marks info))))
 222            ;; Has right readedness.
 223            ;; Check for permanent visibility.
 224            (and gnus-permanently-visible-groups
 225                 (string-match gnus-permanently-visible-groups group))
 226            (memq 'visible params)
 227            (cdr (assq 'visible params)))
 228        ;; Add this group to the list of visible groups.
 229        (push (or entry group) visible-groups)))
 230     (setq visible-groups (nreverse visible-groups))
 231     (when recursive
 232       (if (eq recursive t)
 233           (setq recursive (cdr (gnus-topic-find-topology topic))))
 234       (dolist (topic-topology (cdr recursive))
 235         (setq visible-groups
 236               (nconc visible-groups
 237                      (gnus-topic-find-groups
 238                       (caar topic-topology)
 239                       level all lowest topic-topology)))))
 240     visible-groups))
 241
 242 (defun gnus-topic-goto-previous-topic (n)
 243   "Go to the N'th previous topic."
 244   (interactive "p")
 245   (gnus-topic-goto-next-topic (- n)))
 246
 247 (defun gnus-topic-goto-next-topic (n)
 248   "Go to the N'th next topic."
 249   (interactive "p")
 250   (let ((backward (< n 0))
 251         (n (abs n))
 252         (topic (gnus-current-topic)))
 253     (while (and (> n 0)
 254                 (setq topic
 255                       (if backward
 256                           (gnus-topic-previous-topic topic)
 257                         (gnus-topic-next-topic topic))))
 258       (gnus-topic-goto-topic topic)
 259       (setq n (1- n)))
 260     (when (/= 0 n)
 261       (gnus-message 7 "No more topics"))
 262     n))
 263
 264 (defun gnus-topic-previous-topic (topic)
 265   "Return the previous topic on the same level as TOPIC."
 266   (let ((top (cddr (gnus-topic-find-topology
 267                     (gnus-topic-parent-topic topic)))))
 268     (unless (equal topic (caaar top))
 269       (while (and top (not (equal (caaadr top) topic)))
 270         (setq top (cdr top)))
 271       (caaar top))))
 272
 273 (defun gnus-topic-parent-topic (topic &optional topology)
 274   "Return the parent of TOPIC."
 275   (unless topology
 276     (setq topology gnus-topic-topology))
 277   (let ((parent (car (pop topology)))
 278         result found)
 279     (while (and topology
 280                 (not (setq found (equal (caaar topology) topic)))
 281                 (not (setq result (gnus-topic-parent-topic
 282                                    topic (car topology)))))
 283       (setq topology (cdr topology)))
 284     (or result (and found parent))))
 285
 286 (defun gnus-topic-next-topic (topic &optional previous)
 287   "Return the next sibling of TOPIC."
 288   (let ((parentt (cddr (gnus-topic-find-topology
 289                         (gnus-topic-parent-topic topic))))
 290         prev)
 291     (while (and parentt
 292                 (not (equal (caaar parentt) topic)))
 293       (setq prev (caaar parentt)
 294             parentt (cdr parentt)))
 295     (if previous
 296         prev
 297       (caaadr parentt))))
 298
 299 (defun gnus-topic-forward-topic (num)
 300   "Go to the next topic on the same level as the current one."
 301   (let* ((topic (gnus-current-topic))
 302          (way (if (< num 0) 'gnus-topic-previous-topic
 303                 'gnus-topic-next-topic))
 304          (num (abs num)))
 305     (while (and (not (zerop num))
 306                 (setq topic (funcall way topic)))
 307       (when (gnus-topic-goto-topic topic)
 308         (decf num)))
 309     (unless (zerop num)
 310       (goto-char (point-max)))
 311     num))
 312
 313 (defun gnus-topic-find-topology (topic &optional topology level remove)
 314   "Return the topology of TOPIC."
 315   (unless topology
 316     (setq topology gnus-topic-topology)
 317     (setq level 0))
 318   (let ((top topology)
 319         result)
 320     (if (equal (caar topology) topic)
 321         (progn
 322           (when remove
 323             (delq topology remove))
 324           (cons level topology))
 325       (setq topology (cdr topology))
 326       (while (and topology
 327                   (not (setq result (gnus-topic-find-topology
 328                                      topic (car topology) (1+ level)
 329                                      (and remove top)))))
 330         (setq topology (cdr topology)))
 331       result)))
 332
 333 (defvar gnus-tmp-topics nil)
 334 (defun gnus-topic-list (&optional topology)
 335   "Return a list of all topics in the topology."
 336   (unless topology
 337     (setq topology gnus-topic-topology
 338           gnus-tmp-topics nil))
 339   (push (caar topology) gnus-tmp-topics)
 340   (mapc 'gnus-topic-list (cdr topology))
 341   gnus-tmp-topics)
 342
 343 ;;; Topic parameter jazz
 344
 345 (defun gnus-topic-parameters (topic)
 346   "Return the parameters for TOPIC."
 347   (let ((top (gnus-topic-find-topology topic)))
 348     (when top
 349       (nth 3 (cadr top)))))
 350
 351 (defun gnus-topic-set-parameters (topic parameters)
 352   "Set the topic parameters of TOPIC to PARAMETERS."
 353   (let ((top (gnus-topic-find-topology topic)))
 354     (unless top
 355       (error "No such topic: %s" topic))
 356     ;; We may have to extend if there is no parameters here
 357     ;; to begin with.
 358     (unless (nthcdr 2 (cadr top))
 359       (nconc (cadr top) (list nil)))
 360     (unless (nthcdr 3 (cadr top))
 361       (nconc (cadr top) (list nil)))
 362     (setcar (nthcdr 3 (cadr top)) parameters)
 363     (gnus-dribble-enter
 364      (format "(gnus-topic-set-parameters %S '%S)" topic parameters))))
 365
 366 (defun gnus-group-topic-parameters (group)
 367   "Compute the group parameters for GROUP in topic mode.
 368 Possibly inherit parameters from topics above GROUP."
 369   (let ((params-list (copy-sequence (gnus-group-get-parameter group))))
 370     (save-excursion
 371       (gnus-topic-hierarchical-parameters
 372        ;; First we try to go to the group within the group buffer and find the
 373        ;; topic for the group that way. This hopefully copes well with groups
 374        ;; that are in more than one topic. Failing that (i.e. when the group
 375        ;; isn't visible in the group buffer) we find a topic for the group via
 376        ;; gnus-group-topic.
 377        (or (and (gnus-group-goto-group group)
 378                 (gnus-current-topic))
 379            (gnus-group-topic group))
 380        params-list))))
 381
 382 (defun gnus-topic-hierarchical-parameters (topic &optional group-params-list)
 383   "Compute the topic parameters for TOPIC.
 384 Possibly inherit parameters from topics above TOPIC.
 385 If optional argument GROUP-PARAMS-LIST is non-nil, use it as the basis for
 386 inheritance."
 387   (let ((params-list
 388          ;; We probably have lots of nil elements here, so we remove them.
 389          ;; Probably faster than doing this "properly".
 390          (delq nil (cons group-params-list
 391                          (mapcar 'gnus-topic-parameters
 392                                  (gnus-current-topics topic)))))
 393         param out params)
 394     ;; Now we have all the parameters, so we go through them
 395     ;; and do inheritance in the obvious way.
 396     (let (posting-style)
 397       (while (setq params (pop params-list))
 398         (while (setq param (pop params))
 399           (when (atom param)
 400             (setq param (cons param t)))
 401           (cond ((eq (car param) 'posting-style)
 402                  (let ((param (cdr param))
 403                        elt)
 404                    (while (setq elt (pop param))
 405                      (unless (assoc (car elt) posting-style)
 406                        (push elt posting-style)))))
 407                 (t
 408                  (unless (assq (car param) out)
 409                    (push param out))))))
 410       (and posting-style (push (cons 'posting-style posting-style) out)))
 411     ;; Return the resulting parameter list.
 412     out))
 413
 414 ;;; General utility functions
 415
 416 (defun gnus-topic-enter-dribble ()
 417   (gnus-dribble-enter
 418    (format "(setq gnus-topic-topology '%S)" gnus-topic-topology)))
 419
 420 ;;; Generating group buffers
 421
 422 (defun gnus-group-prepare-topics (level &optional predicate lowest
 423                                         regexp list-topic topic-level)
 424   "List all newsgroups with unread articles of level LEVEL or lower.
 425 Use the `gnus-group-topics' to sort the groups.
 426 If PREDICATE is a function, list groups that the function returns non-nil;
 427 if it is t, list groups that have no unread articles.
 428 If LOWEST is non-nil, list all newsgroups of level LOWEST or higher."
 429   (set-buffer gnus-group-buffer)
 430   (let ((inhibit-read-only t)
 431         (lowest (or lowest 1))
 432         (not-in-list
 433          (and gnus-group-listed-groups
 434               (copy-sequence gnus-group-listed-groups))))
 435
 436     (gnus-update-format-specifications nil 'topic)
 437
 438     (when (or (not gnus-topic-alist)
 439               (not gnus-topology-checked-p))
 440       (gnus-topic-check-topology))
 441
 442     (unless list-topic
 443       (erase-buffer))
 444
 445     ;; List dead groups?
 446     (when (or gnus-group-listed-groups
 447               (and (>= level gnus-level-zombie)
 448                    (<= lowest gnus-level-zombie)))
 449       (gnus-group-prepare-flat-list-dead
 450        (setq gnus-zombie-list (sort gnus-zombie-list 'string<))
 451        gnus-level-zombie ?Z
 452        regexp))
 453
 454     (when (or gnus-group-listed-groups
 455                (and (>= level gnus-level-killed)
 456                     (<= lowest gnus-level-killed)))
 457       (gnus-group-prepare-flat-list-dead
 458        (setq gnus-killed-list (sort gnus-killed-list 'string<))
 459        gnus-level-killed ?K regexp)
 460       (when not-in-list
 461         (unless gnus-killed-hashtb
 462           (gnus-make-hashtable-from-killed))
 463         (gnus-group-prepare-flat-list-dead
 464          (gnus-remove-if (lambda (group)
 465                            (or (gnus-group-entry group)
 466                                (gnus-gethash group gnus-killed-hashtb)))
 467                          not-in-list)
 468          gnus-level-killed ?K regexp)))
 469
 470     ;; Use topics.
 471     (prog1
 472         (when (or (< lowest gnus-level-zombie)
 473                   gnus-group-listed-groups)
 474           (if list-topic
 475               (let ((top (gnus-topic-find-topology list-topic)))
 476                 (gnus-topic-prepare-topic (cdr top) (car top)
 477                                           (or topic-level level) predicate
 478                                           nil lowest regexp))
 479             (gnus-topic-prepare-topic gnus-topic-topology 0
 480                                       (or topic-level level) predicate
 481                                       nil lowest regexp)))
 482       (gnus-group-set-mode-line)
 483       (setq gnus-group-list-mode (cons level predicate))
 484       (gnus-run-hooks 'gnus-group-prepare-hook))))
 485
 486 (defun gnus-topic-prepare-topic (topicl level &optional list-level
 487                                         predicate silent
 488                                         lowest regexp)
 489   "Insert TOPIC into the group buffer.
 490 If SILENT, don't insert anything.  Return the number of unread
 491 articles in the topic and its subtopics."
 492   (let* ((type (pop topicl))
 493          (entries (gnus-topic-find-groups
 494                    (car type)
 495                    (if gnus-group-listed-groups
 496                        gnus-level-killed
 497                      list-level)
 498                    (or predicate gnus-group-listed-groups
 499                        (cdr (assq 'visible
 500                                   (gnus-topic-hierarchical-parameters
 501                                    (car type)))))
 502                    (if gnus-group-listed-groups 0 lowest)))
 503          (visiblep (and (eq (nth 1 type) 'visible) (not silent)))
 504          (gnus-group-indentation
 505           (make-string (* gnus-topic-indent-level level) ? ))
 506          (beg (progn (beginning-of-line) (point)))
 507          (topicl (reverse topicl))
 508          (all-entries entries)
 509          (point-max (point-max))
 510          (unread 0)
 511          info entry end active tick)
 512     ;; Insert any sub-topics.
 513     (while topicl
 514       (incf unread
 515             (gnus-topic-prepare-topic
 516              (pop topicl) (1+ level) list-level predicate
 517              (not visiblep) lowest regexp)))
 518     (setq end (point))
 519     (goto-char beg)
 520     ;; Insert all the groups that belong in this topic.
 521     (while (setq entry (pop entries))
 522       (when (if (stringp entry)
 523                 (gnus-group-prepare-logic
 524                  entry
 525                  (and
 526                   (or (not gnus-group-listed-groups)
 527                       (if (< list-level gnus-level-zombie) nil
 528                         (let ((entry-level
 529                                (if (member entry gnus-zombie-list)
 530                                    gnus-level-zombie gnus-level-killed)))
 531                           (and (<= entry-level list-level)
 532                                (>= entry-level lowest)))))
 533                   (cond
 534                    ((stringp regexp)
 535                     (string-match regexp entry))
 536                    ((functionp regexp)
 537                     (funcall regexp entry))
 538                    ((null regexp) t)
 539                    (t nil))))
 540               (setq info (nth 2 entry))
 541               (gnus-group-prepare-logic
 542                (gnus-info-group info)
 543                (and (or (not gnus-group-listed-groups)
 544                         (let ((entry-level (gnus-info-level info)))
 545                           (and (<= entry-level list-level)
 546                                (>= entry-level lowest))))
 547                     (or (not (functionp predicate))
 548                         (funcall predicate info))
 549                     (or (not (stringp regexp))
 550                         (string-match regexp (gnus-info-group info))))))
 551         (when visiblep
 552           (if (stringp entry)
 553               ;; Dead groups.
 554               (gnus-group-insert-group-line
 555                entry (if (member entry gnus-zombie-list)
 556                          gnus-level-zombie gnus-level-killed)
 557                nil (- (1+ (cdr (setq active (gnus-active entry))))
 558                       (car active))
 559                nil)
 560             ;; Living groups.
 561             (when (setq info (nth 2 entry))
 562               (gnus-group-insert-group-line
 563                (gnus-info-group info)
 564                (gnus-info-level info) (gnus-info-marks info)
 565                (car entry) (gnus-info-method info)))))
 566         (when (and (listp entry)
 567                    (numberp (car entry)))
 568           (incf unread (car entry)))
 569         (when (listp entry)
 570           (setq tick t))))
 571     (goto-char beg)
 572     ;; Insert the topic line.
 573     (when (and (not silent)
 574                (or gnus-topic-display-empty-topics ;We want empty topics
 575                    (not (zerop unread)) ;Non-empty
 576                    tick                 ;Ticked articles
 577                    (/= point-max (point-max)))) ;Inactive groups
 578       (gnus-extent-start-open (point))
 579       (gnus-topic-insert-topic-line
 580        (car type) visiblep
 581        (not (eq (nth 2 type) 'hidden))
 582        level all-entries unread))
 583     (gnus-topic-update-unreads (car type) unread)
 584     (gnus-group--setup-tool-bar-update beg end)
 585     (goto-char end)
 586     unread))
 587
 588 (defun gnus-topic-remove-topic (&optional insert total-remove _hide in-level)
 589   "Remove the current topic."
 590   (let ((topic (gnus-group-topic-name))
 591         (level (gnus-group-topic-level))
 592         (beg (progn (beginning-of-line) (point)))
 593         buffer-read-only)
 594     (when topic
 595       (while (and (zerop (forward-line 1))
 596                   (> (or (gnus-group-topic-level) (1+ level)) level)))
 597       (delete-region beg (point))
 598       ;; Do the change in this rather odd manner because it has been
 599       ;; reported that some topics share parts of some lists, for some
 600       ;; reason.  I have been unable to determine why this is the
 601       ;; case, but this hack seems to take care of things.
 602       (let ((data (cadr (gnus-topic-find-topology topic))))
 603         (setcdr data
 604                 (list (if insert 'visible 'invisible)
 605                       (caddr data)
 606                       (cadddr data))))
 607       (if total-remove
 608           (setq gnus-topic-alist
 609                 (delq (assoc topic gnus-topic-alist) gnus-topic-alist))
 610         (gnus-topic-insert-topic topic in-level)))))
 611
 612 (defun gnus-topic-insert-topic (topic &optional level)
 613   "Insert TOPIC."
 614   (gnus-group-prepare-topics
 615    (car gnus-group-list-mode) (cdr gnus-group-list-mode)
 616    nil nil topic level))
 617
 618 (defun gnus-topic-fold (&optional insert topic)
 619   "Remove/insert the current topic."
 620   (let ((topic (or topic (gnus-group-topic-name))))
 621     (when topic
 622       (save-excursion
 623         (if (not (gnus-group-active-topic-p))
 624             (gnus-topic-remove-topic
 625              (or insert (not (gnus-topic-visible-p))))
 626           (let ((gnus-topic-topology gnus-topic-active-topology)
 627                 (gnus-topic-alist gnus-topic-active-alist)
 628                 (gnus-group-list-mode (cons 5 t)))
 629             (gnus-topic-remove-topic
 630              (or insert (not (gnus-topic-visible-p))) nil nil 9)
 631             (gnus-topic-enter-dribble)))))))
 632
 633 (defvar gnus-tmp-header)
 634
 635 (defun gnus-topic-insert-topic-line (name visiblep shownp level entries
 636                                           &optional unread)
 637   (let* ((visible (if visiblep "" "..."))
 638          (indentation (make-string (* gnus-topic-indent-level level) ? ))
 639          (total-number-of-articles unread)
 640          (number-of-groups (length entries))
 641          (active-topic (eq gnus-topic-alist gnus-topic-active-alist))
 642          gnus-tmp-header)
 643     (gnus-topic-update-unreads name unread)
 644     (beginning-of-line)
 645     ;; Insert the text.
 646     (if shownp
 647         (gnus-add-text-properties
 648          (point)
 649          (prog1 (1+ (point))
 650            (eval gnus-topic-line-format-spec))
 651          (list 'gnus-topic (intern name)
 652                'gnus-topic-level level
 653                'gnus-topic-unread unread
 654                'gnus-active active-topic
 655                'gnus-topic-visible visiblep)))))
 656
 657 (defun gnus-topic-update-unreads (topic unreads)
 658   (setq gnus-topic-unreads (delq (assoc topic gnus-topic-unreads)
 659                                  gnus-topic-unreads))
 660   (push (cons topic unreads) gnus-topic-unreads))
 661
 662 (defun gnus-topic-update-topics-containing-group (group)
 663   "Update all topics that have GROUP as a member."
 664   (when (and (eq major-mode 'gnus-group-mode)
 665              gnus-topic-mode)
 666     (save-excursion
 667       (let ((alist gnus-topic-alist))
 668         ;; This is probably not entirely correct.  If a topic
 669         ;; isn't shown, then it's not updated.  But the updating
 670         ;; should be performed in any case, since the topic's
 671         ;; parent should be updated.  Pfft.
 672         (while alist
 673           (when (and (member group (cdar alist))
 674                      (gnus-topic-goto-topic (caar alist)))
 675             (gnus-topic-update-topic-line (caar alist)))
 676           (pop alist))))))
 677
 678 (defun gnus-topic-update-topic ()
 679   "Update all parent topics to the current group."
 680   (when (and (eq major-mode 'gnus-group-mode)
 681              gnus-topic-mode)
 682     (let ((group (gnus-group-group-name))
 683           (m (point-marker))
 684           (inhibit-read-only t))
 685       (when (and group
 686                  (gnus-get-info group)
 687                  (gnus-topic-goto-topic (gnus-current-topic)))
 688         (gnus-topic-update-topic-line (gnus-group-topic-name))
 689         (goto-char m)
 690         (set-marker m nil)
 691         (gnus-group-position-point)))))
 692
 693 (defun gnus-topic-goto-missing-group (group)
 694   "Place point where GROUP is supposed to be inserted."
 695   (let* ((topic (gnus-group-topic group))
 696          (groups (cdr (assoc topic gnus-topic-alist)))
 697          (g (cdr (member group groups)))
 698          (unfound t))
 699     ;; Try to jump to a visible group.
 700     (while (and g
 701                 (not (gnus-group-goto-group (car g) t)))
 702       (pop g))
 703     ;; It wasn't visible, so we try to see where to insert it.
 704     (when (not g)
 705       (setq g (cdr (member group (reverse groups))))
 706       (while (and g unfound)
 707         (when (gnus-group-goto-group (pop g) t)
 708           (forward-line 1)
 709           (setq unfound nil)))
 710       (when (and unfound
 711                  topic
 712                  (not (gnus-topic-goto-missing-topic topic)))
 713         (gnus-topic-display-missing-topic topic)))))
 714
 715 (defun gnus-topic-display-missing-topic (topic)
 716   "Insert topic lines recursively for missing topics."
 717   (let ((parent (gnus-topic-find-topology
 718                  (gnus-topic-parent-topic topic))))
 719     (when (and parent
 720                (not (gnus-topic-goto-missing-topic (caadr parent))))
 721       (gnus-topic-display-missing-topic (caadr parent))))
 722   (gnus-topic-goto-missing-topic topic)
 723   ;; Skip past all groups in the topic we're in.
 724   (while (gnus-group-group-name)
 725     (forward-line 1))
 726   (let* ((top (gnus-topic-find-topology topic))
 727          (children (cddr top))
 728          (type (cadr top))
 729          (unread 0)
 730          (entries (gnus-topic-find-groups
 731                    (car type) (car gnus-group-list-mode)
 732                    (cdr gnus-group-list-mode)))
 733         entry)
 734     (while children
 735       (incf unread (gnus-topic-unread (caar (pop children)))))
 736     (while (setq entry (pop entries))
 737       (when (numberp (car entry))
 738         (incf unread (car entry))))
 739     (gnus-topic-insert-topic-line
 740      topic t t (car (gnus-topic-find-topology topic)) nil unread)))
 741
 742 (defun gnus-topic-goto-missing-topic (topic)
 743   (if (gnus-topic-goto-topic topic)
 744       (forward-line 1)
 745     ;; Topic not displayed.
 746     (let* ((top (gnus-topic-find-topology
 747                  (gnus-topic-parent-topic topic)))
 748            (tp (reverse (cddr top))))
 749       (if (not top)
 750           (gnus-topic-insert-topic-line
 751            topic t t (car (gnus-topic-find-topology topic)) nil 0)
 752         (while (not (equal (caaar tp) topic))
 753           (setq tp (cdr tp)))
 754         (pop tp)
 755         (while (and tp
 756                     (not (gnus-topic-goto-topic (caaar tp))))
 757           (pop tp))
 758         (if tp
 759             (gnus-topic-forward-topic 1)
 760           (gnus-topic-goto-missing-topic (caadr top)))))
 761     nil))
 762
 763 (defun gnus-topic-update-topic-line (topic-name &optional reads)
 764   (let* ((top (gnus-topic-find-topology topic-name))
 765          (type (cadr top))
 766          (children (cddr top))
 767          (entries (gnus-topic-find-groups
 768                    (car type) (car gnus-group-list-mode)
 769                    (cdr gnus-group-list-mode)))
 770          (parent (gnus-topic-parent-topic topic-name))
 771          (all-entries entries)
 772          (unread 0)
 773          old-unread entry new-unread)
 774     (when (gnus-topic-goto-topic (car type))
 775       ;; Tally all the groups that belong in this topic.
 776       (if reads
 777           (setq unread (- (gnus-group-topic-unread) reads))
 778         (while children
 779           (incf unread (gnus-topic-unread (caar (pop children)))))
 780         (while (setq entry (pop entries))
 781           (when (numberp (car entry))
 782             (incf unread (car entry)))))
 783       (setq old-unread (gnus-group-topic-unread))
 784       ;; Insert the topic line.
 785       (gnus-topic-insert-topic-line
 786        (car type) (gnus-topic-visible-p)
 787        (not (eq (nth 2 type) 'hidden))
 788        (gnus-group-topic-level) all-entries unread)
 789       (gnus-delete-line)
 790       (forward-line -1)
 791       (setq new-unread (gnus-group-topic-unread)))
 792     (when parent
 793       (forward-line -1)
 794       (gnus-topic-update-topic-line
 795        parent
 796        (- (or old-unread 0) (or new-unread 0))))
 797     unread))
 798
 799 (defun gnus-topic-group-indentation ()
 800   (make-string
 801    (* gnus-topic-indent-level
 802       (or (save-excursion
 803             (forward-line -1)
 804             (gnus-topic-goto-topic (gnus-current-topic))
 805             (gnus-group-topic-level))
 806           0))
 807    ? ))
 808
 809 ;;; Initialization
 810
 811 (gnus-add-shutdown 'gnus-topic-close 'gnus)
 812
 813 (defun gnus-topic-close ()
 814   (setq gnus-topic-active-topology nil
 815         gnus-topic-active-alist nil
 816         gnus-topic-killed-topics nil
 817         gnus-topology-checked-p nil))
 818
 819 (defun gnus-topic-check-topology ()
 820   ;; The first time we set the topology to whatever we have
 821   ;; gotten here, which can be rather random.
 822   (unless gnus-topic-alist
 823     (gnus-topic-init-alist))
 824
 825   (setq gnus-topology-checked-p t)
 826   ;; Go through the topic alist and make sure that all topics
 827   ;; are in the topic topology.
 828   (let ((topics (gnus-topic-list))
 829         (alist gnus-topic-alist)
 830         changed)
 831     (while alist
 832       (unless (member (caar alist) topics)
 833         (nconc gnus-topic-topology
 834                (list (list (list (caar alist) 'visible))))
 835         (setq changed t))
 836       (setq alist (cdr alist)))
 837     (when changed
 838       (gnus-topic-enter-dribble))
 839     ;; Conversely, go through the topology and make sure that all
 840     ;; topologies have alists.
 841     (while topics
 842       (unless (assoc (car topics) gnus-topic-alist)
 843         (push (list (car topics)) gnus-topic-alist))
 844       (pop topics)))
 845   ;; Go through all living groups and make sure that
 846   ;; they belong to some topic.
 847   (let* ((tgroups (apply 'append (mapcar 'cdr gnus-topic-alist)))
 848          (entry (last (assoc (caar gnus-topic-topology) gnus-topic-alist)))
 849          (newsrc (cdr gnus-newsrc-alist))
 850          group)
 851     (while newsrc
 852       (unless (member (setq group (gnus-info-group (pop newsrc))) tgroups)
 853         (setcdr entry (list group))
 854         (setq entry (cdr entry)))))
 855   ;; Go through all topics and make sure they contain only living groups.
 856   (let ((alist gnus-topic-alist)
 857         topic)
 858     (while (setq topic (pop alist))
 859       (while (cdr topic)
 860         (if (and (cadr topic)
 861                  (gnus-group-entry (cadr topic)))
 862             (setq topic (cdr topic))
 863           (setcdr topic (cddr topic)))))))
 864
 865 (defun gnus-topic-init-alist ()
 866   "Initialize the topic structures."
 867   (setq gnus-topic-topology
 868         (cons (list "Gnus" 'visible)
 869               (mapcar (lambda (topic)
 870                         (list (list (car topic) 'visible)))
 871                       '(("misc")))))
 872   (setq gnus-topic-alist
 873         (list (cons "misc"
 874                     (mapcar (lambda (info) (gnus-info-group info))
 875                             (cdr gnus-newsrc-alist)))
 876               (list "Gnus")))
 877   (gnus-topic-enter-dribble))
 878
 879 ;;; Maintenance
 880
 881 (defun gnus-topic-clean-alist ()
 882   "Remove bogus groups from the topic alist."
 883   (let ((topic-alist gnus-topic-alist)
 884         result topic)
 885     (unless gnus-killed-hashtb
 886       (gnus-make-hashtable-from-killed))
 887     (while (setq topic (pop topic-alist))
 888       (let ((topic-name (pop topic))
 889             group filtered-topic)
 890         (while (setq group (pop topic))
 891           (when (and (or (gnus-active group)
 892                          (gnus-info-method (gnus-get-info group)))
 893                      (not (gnus-gethash group gnus-killed-hashtb)))
 894             (push group filtered-topic)))
 895         (push (cons topic-name (nreverse filtered-topic)) result)))
 896     (setq gnus-topic-alist (nreverse result))))
 897
 898 (defun gnus-topic-change-level (group level oldlevel &optional previous)
 899   "Run when changing levels to enter/remove groups from topics."
 900   (with-current-buffer gnus-group-buffer
 901     (let ((inhibit-read-only t))
 902       (unless gnus-topic-inhibit-change-level
 903         (gnus-group-goto-group (or (car (nth 2 previous)) group))
 904         (when (and gnus-topic-mode
 905                    gnus-topic-alist
 906                    (not gnus-topic-inhibit-change-level))
 907           ;; Remove the group from the topics.
 908           (if (and (< oldlevel gnus-level-zombie)
 909                    (>= level gnus-level-zombie))
 910               (let ((alist gnus-topic-alist))
 911                 (while (gnus-group-goto-group group)
 912                   (gnus-delete-line))
 913                 (while alist
 914                   (when (member group (car alist))
 915                     (setcdr (car alist) (delete group (cdar alist))))
 916                   (pop alist)))
 917             ;; If the group is subscribed we enter it into the topics.
 918             (when (and (< level gnus-level-zombie)
 919                        (>= oldlevel gnus-level-zombie))
 920               (let* ((prev (gnus-group-group-name))
 921                      (gnus-topic-inhibit-change-level t)
 922                      (gnus-group-indentation
 923                       (make-string
 924                        (* gnus-topic-indent-level
 925                           (or (save-excursion
 926                                 (gnus-topic-goto-topic (gnus-current-topic))
 927                                 (gnus-group-topic-level))
 928                               0))
 929                        ? ))
 930                      (yanked (list group))
 931                      alist talist end)
 932                 ;; Then we enter the yanked groups into the topics
 933                 ;; they belong to.
 934                 (when (setq alist (assoc (save-excursion
 935                                            (forward-line -1)
 936                                            (or
 937                                             (gnus-current-topic)
 938                                             (caar gnus-topic-topology)))
 939                                          gnus-topic-alist))
 940                   (setq talist alist)
 941                   (when (stringp yanked)
 942                     (setq yanked (list yanked)))
 943                   (if (not prev)
 944                       (nconc alist yanked)
 945                     (if (not (cdr alist))
 946                         (setcdr alist (nconc yanked (cdr alist)))
 947                       (while (and (not end) (cdr alist))
 948                         (when (equal (cadr alist) prev)
 949                           (setcdr alist (nconc yanked (cdr alist)))
 950                           (setq end t))
 951                         (setq alist (cdr alist)))
 952                       (unless end
 953                         (nconc talist yanked))))))
 954               (gnus-topic-update-topic))))))))
 955
 956 (defun gnus-topic-goto-next-group (group props)
 957   "Go to group or the next group after group."
 958   (if (not group)
 959       (if (not (memq 'gnus-topic props))
 960           (goto-char (point-max))
 961         (let ((topic (symbol-name (cadr (memq 'gnus-topic props)))))
 962           (or (gnus-topic-goto-topic topic)
 963               (gnus-topic-goto-topic (gnus-topic-next-topic topic)))))
 964     (if (gnus-group-goto-group group)
 965         t
 966       ;; The group is no longer visible.
 967       (let* ((list (assoc (gnus-group-topic group) gnus-topic-alist))
 968              (topic-visible (save-excursion (gnus-topic-goto-topic (car list))))
 969              (after (and topic-visible (cdr (member group (cdr list))))))
 970         ;; First try to put point on a group after the current one.
 971         (while (and after
 972                     (not (gnus-group-goto-group (car after))))
 973           (setq after (cdr after)))
 974         ;; Then try to put point on a group before point.
 975         (unless after
 976           (setq after (cdr (member group (reverse (cdr list)))))
 977           (while (and after
 978                       (not (gnus-group-goto-group (car after))))
 979             (setq after (cdr after))))
 980         ;; Finally, just put point on the topic.
 981         (if (not (car list))
 982             (goto-char (point-min))
 983           (unless after
 984             (if topic-visible
 985                 (gnus-goto-char topic-visible)
 986               (gnus-topic-goto-topic (gnus-topic-next-topic (car list))))
 987             (setq after nil)))
 988         t))))
 989
 990 ;;; Topic-active functions
 991
 992 (defun gnus-topic-grok-active (&optional force)
 993   "Parse all active groups and create topic structures for them."
 994   ;; First we make sure that we have really read the active file.
 995   (when (or force
 996             (not gnus-topic-active-alist))
 997     (let (groups)
 998       ;; Get a list of all groups available.
 999       (mapatoms (lambda (g) (when (symbol-value g)
1000                               (push (symbol-name g) groups)))
1001                 gnus-active-hashtb)
1002       (setq groups (sort groups 'string<))
1003       ;; Init the variables.
1004       (setq gnus-topic-active-topology (list (list "" 'visible)))
1005       (setq gnus-topic-active-alist nil)
1006       ;; Descend the top-level hierarchy.
1007       (gnus-topic-grok-active-1 gnus-topic-active-topology groups)
1008       ;; Set the top-level topic names to something nice.
1009       (setcar (car gnus-topic-active-topology) "Gnus active")
1010       (setcar (car gnus-topic-active-alist) "Gnus active"))))
1011
1012 (defun gnus-topic-grok-active-1 (topology groups)
1013   (let* ((name (caar topology))
1014          (prefix (concat "^" (regexp-quote name)))
1015          tgroups ntopology group)
1016     (while (and groups
1017                 (string-match prefix (setq group (car groups))))
1018       (if (not (string-match "\\." group (match-end 0)))
1019           ;; There are no further hierarchies here, so we just
1020           ;; enter this group into the list belonging to this
1021           ;; topic.
1022           (push (pop groups) tgroups)
1023         ;; New sub-hierarchy, so we add it to the topology.
1024         (nconc topology (list (setq ntopology
1025                                     (list (list (substring
1026                                                  group 0 (match-end 0))
1027                                                 'invisible)))))
1028         ;; Descend the hierarchy.
1029         (setq groups (gnus-topic-grok-active-1 ntopology groups))))
1030     ;; We remove the trailing "." from the topic name.
1031     (setq name
1032           (if (string-match "\\.$" name)
1033               (substring name 0 (match-beginning 0))
1034             name))
1035     ;; Add this topic and its groups to the topic alist.
1036     (push (cons name (nreverse tgroups)) gnus-topic-active-alist)
1037     (setcar (car topology) name)
1038     ;; We return the rest of the groups that didn't belong
1039     ;; to this topic.
1040     groups))
1041
1042 ;;; Topic mode, commands and keymap.
1043
1044 (defvar gnus-topic-mode-map nil)
1045 (defvar gnus-group-topic-map nil)
1046
1047 (unless gnus-topic-mode-map
1048   (setq gnus-topic-mode-map (make-sparse-keymap))
1049
1050   ;; Override certain group mode keys.
1051   (gnus-define-keys gnus-topic-mode-map
1052     "=" gnus-topic-select-group
1053     "\r" gnus-topic-select-group
1054     " " gnus-topic-read-group
1055     "\C-c\C-x" gnus-topic-expire-articles
1056     "c" gnus-topic-catchup-articles
1057     "\C-k" gnus-topic-kill-group
1058     "\C-y" gnus-topic-yank-group
1059     "\M-g" gnus-topic-get-new-news-this-topic
1060     "AT" gnus-topic-list-active
1061     "Gp" gnus-topic-edit-parameters
1062     "#" gnus-topic-mark-topic
1063     "\M-#" gnus-topic-unmark-topic
1064     [tab] gnus-topic-indent
1065     [(meta tab)] gnus-topic-unindent
1066     "\C-i" gnus-topic-indent
1067     "\M-\C-i" gnus-topic-unindent
1068     gnus-mouse-2 gnus-mouse-pick-topic)
1069
1070   ;; Define a new submap.
1071   (gnus-define-keys (gnus-group-topic-map "T" gnus-group-mode-map)
1072     "#" gnus-topic-mark-topic
1073     "\M-#" gnus-topic-unmark-topic
1074     "n" gnus-topic-create-topic
1075     "m" gnus-topic-move-group
1076     "D" gnus-topic-remove-group
1077     "c" gnus-topic-copy-group
1078     "h" gnus-topic-hide-topic
1079     "s" gnus-topic-show-topic
1080     "j" gnus-topic-jump-to-topic
1081     "M" gnus-topic-move-matching
1082     "C" gnus-topic-copy-matching
1083     "\M-p" gnus-topic-goto-previous-topic
1084     "\M-n" gnus-topic-goto-next-topic
1085     "\C-i" gnus-topic-indent
1086     [tab] gnus-topic-indent
1087     "r" gnus-topic-rename
1088     "\177" gnus-topic-delete
1089     [delete] gnus-topic-delete
1090     "H" gnus-topic-toggle-display-empty-topics)
1091
1092   (gnus-define-keys (gnus-topic-sort-map "S" gnus-group-topic-map)
1093     "s" gnus-topic-sort-groups
1094     "a" gnus-topic-sort-groups-by-alphabet
1095     "u" gnus-topic-sort-groups-by-unread
1096     "l" gnus-topic-sort-groups-by-level
1097     "e" gnus-topic-sort-groups-by-server
1098     "v" gnus-topic-sort-groups-by-score
1099     "r" gnus-topic-sort-groups-by-rank
1100     "m" gnus-topic-sort-groups-by-method))
1101
1102 (defun gnus-topic-make-menu-bar ()
1103   (unless (boundp 'gnus-topic-menu)
1104     (easy-menu-define
1105      gnus-topic-menu gnus-topic-mode-map ""
1106      '("Topics"
1107        ["Toggle topics" gnus-topic-mode t]
1108        ("Groups"
1109         ["Copy..." gnus-topic-copy-group t]
1110         ["Move..." gnus-topic-move-group t]
1111         ["Remove" gnus-topic-remove-group t]
1112         ["Copy matching..." gnus-topic-copy-matching t]
1113         ["Move matching..." gnus-topic-move-matching t])
1114        ("Topics"
1115         ["Goto..." gnus-topic-jump-to-topic t]
1116         ["Show" gnus-topic-show-topic t]
1117         ["Hide" gnus-topic-hide-topic t]
1118         ["Delete" gnus-topic-delete t]
1119         ["Rename..." gnus-topic-rename t]
1120         ["Create..." gnus-topic-create-topic t]
1121         ["Mark" gnus-topic-mark-topic t]
1122         ["Indent" gnus-topic-indent t]
1123         ["Sort" gnus-topic-sort-topics t]
1124         ["Previous topic" gnus-topic-goto-previous-topic t]
1125         ["Next topic" gnus-topic-goto-next-topic t]
1126         ["Toggle hide empty" gnus-topic-toggle-display-empty-topics t]
1127         ["Edit parameters" gnus-topic-edit-parameters t])
1128        ["List active" gnus-topic-list-active t]))))
1129
1130 (define-minor-mode gnus-topic-mode
1131   "Minor mode for topicsifying Gnus group buffers."
1132   :lighter " Topic" :keymap gnus-topic-mode-map
1133   (if (not (derived-mode-p 'gnus-group-mode))
1134       (setq gnus-topic-mode nil)
1135     ;; Infest Gnus with topics.
1136     (if (not gnus-topic-mode)
1137         (setq gnus-goto-missing-group-function nil)
1138       (when (gnus-visual-p 'topic-menu 'menu)
1139         (gnus-topic-make-menu-bar))
1140       (gnus-set-format 'topic t)
1141       (add-hook 'gnus-group-catchup-group-hook 'gnus-topic-update-topic)
1142       (set (make-local-variable 'gnus-group-prepare-function)
1143            'gnus-group-prepare-topics)
1144       (set (make-local-variable 'gnus-group-get-parameter-function)
1145            'gnus-group-topic-parameters)
1146       (set (make-local-variable 'gnus-group-goto-next-group-function)
1147            'gnus-topic-goto-next-group)
1148       (set (make-local-variable 'gnus-group-indentation-function)
1149            'gnus-topic-group-indentation)
1150       (set (make-local-variable 'gnus-group-update-group-function)
1151            'gnus-topic-update-topics-containing-group)
1152       (set (make-local-variable 'gnus-group-sort-alist-function)
1153            'gnus-group-sort-topic)
1154       (setq gnus-group-change-level-function 'gnus-topic-change-level)
1155       (setq gnus-goto-missing-group-function 'gnus-topic-goto-missing-group)
1156       (gnus-make-local-hook 'gnus-check-bogus-groups-hook)
1157       (add-hook 'gnus-check-bogus-groups-hook 'gnus-topic-clean-alist
1158                 nil 'local)
1159       (setq gnus-topology-checked-p nil)
1160       ;; We check the topology.
1161       (when gnus-newsrc-alist
1162         (gnus-topic-check-topology)))
1163     ;; Remove topic infestation.
1164     (unless gnus-topic-mode
1165       (remove-hook 'gnus-summary-exit-hook 'gnus-topic-update-topic)
1166       (setq gnus-group-change-level-function nil)
1167       (remove-hook 'gnus-check-bogus-groups-hook 'gnus-topic-clean-alist)
1168       (setq gnus-group-prepare-function 'gnus-group-prepare-flat)
1169       (setq gnus-group-sort-alist-function 'gnus-group-sort-flat))
1170     (when (gmm-called-interactively-p 'any)
1171       (gnus-group-list-groups))))
1172
1173 (defun gnus-topic-select-group (&optional all)
1174   "Select this newsgroup.
1175 No article is selected automatically.
1176 If the group is opened, just switch the summary buffer.
1177 If ALL is non-nil, already read articles become readable.
1178
1179 If ALL is a positive number, fetch this number of the latest
1180 articles in the group.  If ALL is a negative number, fetch this
1181 number of the earliest articles in the group.
1182
1183 If performed over a topic line, toggle folding the topic."
1184   (interactive "P")
1185   (when (and (eobp) (not (gnus-group-group-name)))
1186     (forward-line -1))
1187   (if (gnus-group-topic-p)
1188       (let ((gnus-group-list-mode
1189              (if all (cons (if (numberp all) all 7) t) gnus-group-list-mode)))
1190         (gnus-topic-fold all)
1191         (gnus-dribble-touch))
1192     (gnus-group-select-group all)))
1193
1194 (defun gnus-mouse-pick-topic (e)
1195   "Select the group or topic under the mouse pointer."
1196   (interactive "e")
1197   (mouse-set-point e)
1198   (gnus-topic-read-group nil))
1199
1200 (defun gnus-topic-expire-articles (topic)
1201   "Expire articles in this topic or group."
1202   (interactive (list (gnus-group-topic-name)))
1203   (if (not topic)
1204       (call-interactively 'gnus-group-expire-articles)
1205     (save-excursion
1206       (gnus-message 5 "Expiring groups in %s..." topic)
1207       (let ((gnus-group-marked
1208              (mapcar (lambda (entry) (car (nth 2 entry)))
1209                      (gnus-topic-find-groups topic gnus-level-killed t
1210                                              nil t))))
1211         (gnus-group-expire-articles nil))
1212       (gnus-message 5 "Expiring groups in %s...done" topic))))
1213
1214 (defun gnus-topic-catchup-articles (topic)
1215   "Catchup this topic or group.
1216 Also see `gnus-group-catchup'."
1217   (interactive (list (gnus-group-topic-name)))
1218   (if (not topic)
1219       (call-interactively 'gnus-group-catchup-current)
1220     (save-excursion
1221       (let* ((groups
1222               (mapcar (lambda (entry) (car (nth 2 entry)))
1223                       (gnus-topic-find-groups topic gnus-level-killed t
1224                                               nil t)))
1225              (inhibit-read-only t)
1226              (gnus-group-marked groups))
1227         (gnus-group-catchup-current)
1228         (mapcar 'gnus-topic-update-topics-containing-group groups)))))
1229
1230 (defun gnus-topic-read-group (&optional all no-article group)
1231   "Read news in this newsgroup.
1232 If the prefix argument ALL is non-nil, already read articles become
1233 readable.
1234
1235 If ALL is a positive number, fetch this number of the latest
1236 articles in the group.  If ALL is a negative number, fetch this
1237 number of the earliest articles in the group.
1238
1239 If the optional argument NO-ARTICLE is non-nil, no article will
1240 be auto-selected upon group entry.  If GROUP is non-nil, fetch
1241 that group.
1242
1243 If performed over a topic line, toggle folding the topic."
1244   (interactive "P")
1245   (when (and (eobp) (not (gnus-group-group-name)))
1246     (forward-line -1))
1247   (if (gnus-group-topic-p)
1248       (let ((gnus-group-list-mode
1249              (if all (cons (if (numberp all) all 7) t) gnus-group-list-mode)))
1250         (gnus-topic-fold all))
1251     (gnus-group-read-group all no-article group)))
1252
1253 (defun gnus-topic-create-topic (topic parent &optional previous full-topic)
1254   "Create a new TOPIC under PARENT.
1255 When used interactively, PARENT will be the topic under point."
1256   (interactive
1257    (list
1258     (read-string "New topic: ")
1259     (gnus-current-topic)))
1260   ;; Check whether this topic already exists.
1261   (when (gnus-topic-find-topology topic)
1262     (error "Topic already exists"))
1263   (unless parent
1264     (setq parent (caar gnus-topic-topology)))
1265   (let ((top (cdr (gnus-topic-find-topology parent)))
1266         (full-topic (or full-topic (list (list topic 'visible nil nil)))))
1267     (unless top
1268       (error "No such parent topic: %s" parent))
1269     (if previous
1270         (progn
1271           (while (and (cdr top)
1272                       (not (equal (caaadr top) previous)))
1273             (setq top (cdr top)))
1274           (setcdr top (cons full-topic (cdr top))))
1275       (nconc top (list full-topic)))
1276     (unless (assoc topic gnus-topic-alist)
1277       (push (list topic) gnus-topic-alist)))
1278   (gnus-topic-enter-dribble)
1279   (gnus-group-list-groups)
1280   (gnus-topic-goto-topic topic))
1281
1282 ;; FIXME:
1283 ;;  1. When the marked groups are overlapped with the process
1284 ;;     region, the behavior of move or remove is not right.
1285 ;;  2. Can't process on several marked groups with a same name,
1286 ;;     because gnus-group-marked only keeps one copy.
1287
1288 (defvar gnus-topic-history nil)
1289
1290 (defun gnus-topic-move-group (n topic &optional copyp)
1291   "Move the next N groups to TOPIC.
1292 If COPYP, copy the groups instead."
1293   (interactive
1294    (list current-prefix-arg
1295          (gnus-completing-read "Move to topic" (mapcar 'car gnus-topic-alist) t
1296                                nil 'gnus-topic-history)))
1297   (let ((use-marked (and (not n) (not (gnus-region-active-p))
1298                          gnus-group-marked t))
1299         (groups (gnus-group-process-prefix n))
1300         (topicl (assoc topic gnus-topic-alist))
1301         (start-topic (gnus-group-topic-name))
1302         (start-group (progn (forward-line 1) (gnus-group-group-name)))
1303         entry)
1304     (if (and (not groups) (not copyp) start-topic)
1305         (gnus-topic-move start-topic topic)
1306       (dolist (g groups)
1307         (gnus-group-remove-mark g use-marked)
1308         (when (and
1309                (setq entry (assoc (gnus-current-topic) gnus-topic-alist))
1310                (not copyp))
1311           (setcdr entry (gnus-delete-first g (cdr entry))))
1312         (nconc topicl (list g)))
1313       (gnus-topic-enter-dribble)
1314       (if start-group
1315           (gnus-group-goto-group start-group)
1316         (gnus-topic-goto-topic start-topic))
1317       (gnus-group-list-groups))))
1318
1319 (defun gnus-topic-remove-group (&optional n)
1320   "Remove the current group from the topic."
1321   (interactive "P")
1322   (let ((use-marked (and (not n) (not (gnus-region-active-p))
1323                          gnus-group-marked t))
1324         (groups (gnus-group-process-prefix n)))
1325     (mapc
1326      (lambda (group)
1327        (gnus-group-remove-mark group use-marked)
1328        (let ((topicl (assoc (gnus-current-topic) gnus-topic-alist))
1329              (inhibit-read-only t))
1330          (when (and topicl group)
1331            (gnus-delete-line)
1332            (gnus-delete-first group topicl))
1333          (gnus-topic-update-topic)))
1334      groups)
1335     (gnus-topic-enter-dribble)
1336     (gnus-group-position-point)))
1337
1338 (defun gnus-topic-copy-group (n topic)
1339   "Copy the current group to a topic."
1340   (interactive
1341    (list current-prefix-arg
1342          (gnus-completing-read
1343           "Copy to topic" (mapcar 'car gnus-topic-alist) t)))
1344   (gnus-topic-move-group n topic t))
1345
1346 (defun gnus-topic-kill-group (&optional n discard)
1347   "Kill the next N groups."
1348   (interactive "P")
1349   (if (gnus-group-topic-p)
1350       (let ((topic (gnus-group-topic-name)))
1351         (push (cons
1352                (gnus-topic-find-topology topic)
1353                (assoc topic gnus-topic-alist))
1354               gnus-topic-killed-topics)
1355         (gnus-topic-remove-topic nil t)
1356         (gnus-topic-find-topology topic nil nil gnus-topic-topology)
1357         (gnus-topic-enter-dribble))
1358     (gnus-group-kill-group n discard)
1359     (if (not (gnus-group-topic-p))
1360         (gnus-topic-update-topic)
1361       ;; Move up one line so that we update the right topic.
1362       (forward-line -1)
1363       (gnus-topic-update-topic)
1364       (forward-line 1))))
1365
1366 (defun gnus-topic-yank-group (&optional arg)
1367   "Yank the last topic."
1368   (interactive "p")
1369   (if gnus-topic-killed-topics
1370       (let* ((previous
1371               (or (gnus-group-topic-name)
1372                   (gnus-topic-next-topic (gnus-current-topic))))
1373              (data (pop gnus-topic-killed-topics))
1374              (alist (cdr data))
1375              (item (cdar data)))
1376         (push alist gnus-topic-alist)
1377         (gnus-topic-create-topic
1378          (caar item) (gnus-topic-parent-topic previous) previous
1379          item)
1380         (gnus-topic-enter-dribble)
1381         (gnus-topic-goto-topic (caar item)))
1382     (let* ((prev (gnus-group-group-name))
1383            (gnus-topic-inhibit-change-level t)
1384            (gnus-group-indentation
1385             (make-string
1386              (* gnus-topic-indent-level
1387                 (or (save-excursion
1388                       (gnus-topic-goto-topic (gnus-current-topic))
1389                       (gnus-group-topic-level))
1390                     0))
1391              ? ))
1392            yanked alist)
1393       ;; We first yank the groups the normal way...
1394       (setq yanked (gnus-group-yank-group arg))
1395       ;; Then we enter the yanked groups into the topics they belong
1396       ;; to.
1397       (setq alist (assoc (save-excursion
1398                            (forward-line -1)
1399                            (gnus-current-topic))
1400                          gnus-topic-alist))
1401       (when (stringp yanked)
1402         (setq yanked (list yanked)))
1403       (if (not prev)
1404           (nconc alist yanked)
1405         (if (not (cdr alist))
1406             (setcdr alist (nconc yanked (cdr alist)))
1407           (while (cdr alist)
1408             (when (equal (cadr alist) prev)
1409               (setcdr alist (nconc yanked (cdr alist)))
1410               (setq alist nil))
1411             (setq alist (cdr alist))))))
1412     (gnus-topic-update-topic)))
1413
1414 (defun gnus-topic-hide-topic (&optional permanent)
1415   "Hide the current topic.
1416 If PERMANENT, make it stay hidden in subsequent sessions as well."
1417   (interactive "P")
1418   (when (gnus-current-topic)
1419     (gnus-topic-goto-topic (gnus-current-topic))
1420     (if permanent
1421         (setcar (cddr
1422                  (cadr
1423                   (gnus-topic-find-topology (gnus-current-topic))))
1424                 'hidden))
1425     (gnus-topic-remove-topic nil nil)))
1426
1427 (defun gnus-topic-show-topic (&optional permanent)
1428   "Show the hidden topic.
1429 If PERMANENT, make it stay shown in subsequent sessions as well."
1430   (interactive "P")
1431   (when (gnus-group-topic-p)
1432     (if (not permanent)
1433         (gnus-topic-remove-topic t nil)
1434       (let ((topic
1435              (gnus-topic-find-topology
1436               (gnus-completing-read "Show topic"
1437                                     (mapcar 'car gnus-topic-alist) t))))
1438         (setcar (cddr (cadr topic)) nil)
1439         (setcar (cdr (cadr topic)) 'visible)
1440         (gnus-group-list-groups)))))
1441
1442 (defun gnus-topic-mark-topic (topic &optional unmark non-recursive)
1443   "Mark all groups in the TOPIC with the process mark.
1444 If NON-RECURSIVE (which is the prefix) is t, don't mark its subtopics."
1445   (interactive (list (gnus-group-topic-name)
1446                      nil
1447                      (and current-prefix-arg t)))
1448   (if (not topic)
1449       (call-interactively 'gnus-group-mark-group)
1450     (save-excursion
1451       (let ((groups (gnus-topic-find-groups topic gnus-level-killed t nil
1452                                             (not non-recursive))))
1453         (while groups
1454           (funcall (if unmark 'gnus-group-remove-mark 'gnus-group-set-mark)
1455                    (gnus-info-group (nth 2 (pop groups)))))))))
1456
1457 (defun gnus-topic-unmark-topic (topic &optional _dummy non-recursive)
1458   "Remove the process mark from all groups in the TOPIC.
1459 If NON-RECURSIVE (which is the prefix) is t, don't unmark its subtopics."
1460   (interactive (list (gnus-group-topic-name)
1461                      nil
1462                      (and current-prefix-arg t)))
1463   (if (not topic)
1464       (call-interactively 'gnus-group-unmark-group)
1465     (gnus-topic-mark-topic topic t non-recursive)))
1466
1467 (defun gnus-topic-get-new-news-this-topic (&optional n)
1468   "Check for new news in the current topic."
1469   (interactive "P")
1470   (if (not (gnus-group-topic-p))
1471       (gnus-group-get-new-news-this-group n)
1472     (let* ((topic (gnus-group-topic-name))
1473            (data (cadr (gnus-topic-find-topology topic))))
1474       (save-excursion
1475         (gnus-topic-mark-topic topic nil (and n t))
1476         (gnus-group-get-new-news-this-group))
1477       (gnus-topic-remove-topic (eq 'visible (cadr data))))))
1478
1479 (defun gnus-topic-move-matching (regexp topic &optional copyp)
1480   "Move all groups that match REGEXP to some topic."
1481   (interactive
1482    (let (topic)
1483      (nreverse
1484       (list
1485        (setq topic (gnus-completing-read "Move to topic"
1486                                          (mapcar 'car gnus-topic-alist) t))
1487        (read-string (format "Move to %s (regexp): " topic))))))
1488   (gnus-group-mark-regexp regexp)
1489   (gnus-topic-move-group nil topic copyp))
1490
1491 (defun gnus-topic-copy-matching (regexp topic &optional _copyp)
1492   "Copy all groups that match REGEXP to some topic."
1493   (interactive
1494    (let ((topic (gnus-completing-read "Copy to topic"
1495                                       (mapcar #'car gnus-topic-alist) t)))
1496      (nreverse
1497       (list topic
1498             (read-string (format "Copy to %s (regexp): " topic))))))
1499   (gnus-topic-move-matching regexp topic t))
1500
1501 (defun gnus-topic-delete (topic)
1502   "Delete a topic."
1503   (interactive (list (gnus-group-topic-name)))
1504   (unless topic
1505     (error "No topic to be deleted"))
1506   (let ((entry (assoc topic gnus-topic-alist))
1507         (inhibit-read-only t))
1508     (when (cdr entry)
1509       (error "Topic not empty"))
1510     ;; Delete if visible.
1511     (when (gnus-topic-goto-topic topic)
1512       (gnus-delete-line))
1513     ;; Remove from alist.
1514     (setq gnus-topic-alist (delq entry gnus-topic-alist))
1515     ;; Remove from topology.
1516     (gnus-topic-find-topology topic nil nil 'delete)
1517     (gnus-dribble-touch)))
1518
1519 (defun gnus-topic-rename (old-name new-name)
1520   "Rename a topic."
1521   (interactive
1522    (let ((topic (gnus-current-topic)))
1523      (list topic
1524            (read-string (format "Rename %s to: " topic) topic))))
1525   ;; Check whether the new name exists.
1526   (when (gnus-topic-find-topology new-name)
1527     (error "Topic `%s' already exists" new-name))
1528   ;; "nil" is an invalid name, for reasons I'd rather not go
1529   ;; into here.  Trust me.
1530   (when (equal new-name "nil")
1531     (error "Invalid name: %s" nil))
1532   ;; Do the renaming.
1533   (let ((top (gnus-topic-find-topology old-name))
1534         (entry (assoc old-name gnus-topic-alist)))
1535     (when top
1536       (setcar (cadr top) new-name))
1537     (when entry
1538       (setcar entry new-name))
1539     (forward-line -1)
1540     (gnus-dribble-touch)
1541     (gnus-group-list-groups)
1542     (forward-line 1)))
1543
1544 (defun gnus-topic-indent (&optional unindent)
1545   "Indent a topic -- make it a sub-topic of the previous topic.
1546 If UNINDENT, remove an indentation."
1547   (interactive "P")
1548   (if unindent
1549       (gnus-topic-unindent)
1550     (let* ((topic (gnus-current-topic))
1551            (parent (gnus-topic-previous-topic topic))
1552            (inhibit-read-only t))
1553       (unless parent
1554         (error "Nothing to indent %s into" topic))
1555       (when topic
1556         (gnus-topic-goto-topic topic)
1557         (gnus-topic-kill-group)
1558         (push (cdar gnus-topic-killed-topics) gnus-topic-alist)
1559         (gnus-topic-create-topic
1560          topic parent nil (cdar (car gnus-topic-killed-topics)))
1561         (pop gnus-topic-killed-topics)
1562         (or (gnus-topic-goto-topic topic)
1563             (gnus-topic-goto-topic parent))))))
1564
1565 (defun gnus-topic-unindent ()
1566   "Unindent a topic."
1567   (interactive)
1568   (let* ((topic (gnus-current-topic))
1569          (parent (gnus-topic-parent-topic topic))
1570          (grandparent (gnus-topic-parent-topic parent)))
1571     (unless grandparent
1572       (error "Nothing to indent %s into" topic))
1573     (when topic
1574       (gnus-topic-goto-topic topic)
1575       (gnus-topic-kill-group)
1576       (push (cdar gnus-topic-killed-topics) gnus-topic-alist)
1577       (gnus-topic-create-topic
1578        topic grandparent (gnus-topic-next-topic parent)
1579        (cdar (car gnus-topic-killed-topics)))
1580       (pop gnus-topic-killed-topics)
1581       (gnus-topic-goto-topic topic))))
1582
1583 (defun gnus-topic-list-active (&optional force)
1584   "List all groups that Gnus knows about in a topicsified fashion.
1585 If FORCE, always re-read the active file."
1586   (interactive "P")
1587   (when force
1588     (gnus-get-killed-groups))
1589   (gnus-topic-grok-active force)
1590   (let ((gnus-topic-topology gnus-topic-active-topology)
1591         (gnus-topic-alist gnus-topic-active-alist)
1592         gnus-killed-list gnus-zombie-list)
1593     (gnus-group-list-groups gnus-level-killed nil 1)))
1594
1595 (defun gnus-topic-toggle-display-empty-topics ()
1596   "Show/hide topics that have no unread articles."
1597   (interactive)
1598   (setq gnus-topic-display-empty-topics
1599         (not gnus-topic-display-empty-topics))
1600   (gnus-group-list-groups)
1601   (message "%s empty topics"
1602            (if gnus-topic-display-empty-topics
1603                "Showing" "Hiding")))
1604
1605 ;;; Topic sorting functions
1606
1607 (defun gnus-topic-edit-parameters (group)
1608   "Edit the group parameters of GROUP.
1609 If performed on a topic, edit the topic parameters instead."
1610   (interactive (list (gnus-group-group-name)))
1611   (if group
1612       (gnus-group-edit-group-parameters group)
1613     (if (not (gnus-group-topic-p))
1614         (error "Nothing to edit on the current line")
1615       (let ((topic (gnus-group-topic-name)))
1616         (gnus-edit-form
1617          (gnus-topic-parameters topic)
1618          (gnus-format-message "Editing the topic parameters for `%s'."
1619                               (or group topic))
1620          `(lambda (form)
1621             (gnus-topic-set-parameters ,topic form)))))))
1622
1623 (defun gnus-group-sort-topic (func reverse)
1624   "Sort groups in the topics according to FUNC and REVERSE."
1625   (let ((alist gnus-topic-alist))
1626     (while alist
1627       ;; !!!Sometimes nil elements sneak into the alist,
1628       ;; for some reason or other.
1629       (setcar alist (delq nil (car alist)))
1630       (setcar alist (delete "dummy.group" (car alist)))
1631       (gnus-topic-sort-topic (pop alist) func reverse))))
1632
1633 (defun gnus-topic-sort-topic (topic func reverse)
1634   ;; Each topic only lists the name of the group, while
1635   ;; the sort predicates expect group infos as inputs.
1636   ;; So we first transform the group names into infos,
1637   ;; then sort, and then transform back into group names.
1638   (setcdr
1639    topic
1640    (mapcar
1641     (lambda (info) (gnus-info-group info))
1642     (sort
1643      (mapcar
1644       (lambda (group) (gnus-get-info group))
1645       (cdr topic))
1646      func)))
1647   ;; Do the reversal, if necessary.
1648   (when reverse
1649     (setcdr topic (nreverse (cdr topic)))))
1650
1651 (defun gnus-topic-sort-groups (func &optional reverse)
1652   "Sort the current topic according to FUNC.
1653 If REVERSE, reverse the sorting order."
1654   (interactive (list gnus-group-sort-function current-prefix-arg))
1655   (let ((topic (assoc (gnus-current-topic) gnus-topic-alist)))
1656     (gnus-topic-sort-topic
1657      topic (gnus-make-sort-function func) reverse)
1658     (gnus-group-list-groups)))
1659
1660 (defun gnus-topic-sort-groups-by-alphabet (&optional reverse)
1661   "Sort the current topic alphabetically by group name.
1662 If REVERSE, sort in reverse order."
1663   (interactive "P")
1664   (gnus-topic-sort-groups 'gnus-group-sort-by-alphabet reverse))
1665
1666 (defun gnus-topic-sort-groups-by-unread (&optional reverse)
1667   "Sort the current topic by number of unread articles.
1668 If REVERSE, sort in reverse order."
1669   (interactive "P")
1670   (gnus-topic-sort-groups 'gnus-group-sort-by-unread reverse))
1671
1672 (defun gnus-topic-sort-groups-by-level (&optional reverse)
1673   "Sort the current topic by group level.
1674 If REVERSE, sort in reverse order."
1675   (interactive "P")
1676   (gnus-topic-sort-groups 'gnus-group-sort-by-level reverse))
1677
1678 (defun gnus-topic-sort-groups-by-score (&optional reverse)
1679   "Sort the current topic by group score.
1680 If REVERSE, sort in reverse order."
1681   (interactive "P")
1682   (gnus-topic-sort-groups 'gnus-group-sort-by-score reverse))
1683
1684 (defun gnus-topic-sort-groups-by-rank (&optional reverse)
1685   "Sort the current topic by group rank.
1686 If REVERSE, sort in reverse order."
1687   (interactive "P")
1688   (gnus-topic-sort-groups 'gnus-group-sort-by-rank reverse))
1689
1690 (defun gnus-topic-sort-groups-by-method (&optional reverse)
1691   "Sort the current topic alphabetically by backend name.
1692 If REVERSE, sort in reverse order."
1693   (interactive "P")
1694   (gnus-topic-sort-groups 'gnus-group-sort-by-method reverse))
1695
1696 (defun gnus-topic-sort-groups-by-server (&optional reverse)
1697   "Sort the current topic alphabetically by server name.
1698 If REVERSE, sort in reverse order."
1699   (interactive "P")
1700   (gnus-topic-sort-groups 'gnus-group-sort-by-server reverse))
1701
1702 (defun gnus-topic-sort-topics-1 (top reverse)
1703   (if (cdr top)
1704       (let ((subtop
1705              (mapcar (gnus-byte-compile
1706                       `(lambda (top)
1707                          (gnus-topic-sort-topics-1 top ,reverse)))
1708                      (sort (cdr top)
1709                            (lambda (t1 t2)
1710                              (string-lessp (caar t1) (caar t2)))))))
1711         (setcdr top (if reverse (reverse subtop) subtop))))
1712   top)
1713
1714 (defun gnus-topic-sort-topics (&optional topic reverse)
1715   "Sort topics in TOPIC alphabetically by topic name.
1716 If REVERSE, reverse the sorting order."
1717   (interactive
1718    (list (gnus-completing-read "Sort topics in"
1719                                (mapcar 'car gnus-topic-alist) t
1720                                (gnus-current-topic))
1721          current-prefix-arg))
1722   (let ((topic-topology (or (and topic (cdr (gnus-topic-find-topology topic)))
1723                             gnus-topic-topology)))
1724     (gnus-topic-sort-topics-1 topic-topology reverse)
1725     (gnus-topic-enter-dribble)
1726     (gnus-group-list-groups)
1727     (gnus-topic-goto-topic topic)))
1728
1729 (defun gnus-topic-move (current to)
1730   "Move the CURRENT topic to TO."
1731   (interactive
1732    (list
1733     (gnus-group-topic-name)
1734     (gnus-completing-read "Move to topic" (mapcar 'car gnus-topic-alist) t)))
1735   (unless (and current to)
1736     (error "Can't find topic"))
1737   (let ((current-top (cdr (gnus-topic-find-topology current)))
1738         (to-top (cdr (gnus-topic-find-topology to))))
1739     (unless current-top
1740       (error "Can't find topic `%s'" current))
1741     (unless to-top
1742       (error "Can't find topic `%s'" to))
1743     (if (gnus-topic-find-topology to current-top 0);; Don't care the level
1744         (error "Can't move `%s' to its sub-level" current))
1745     (gnus-topic-find-topology current nil nil 'delete)
1746     (setcdr (last to-top) (list current-top))
1747     (gnus-topic-enter-dribble)
1748     (gnus-group-list-groups)
1749     (gnus-topic-goto-topic current)))
1750
1751 (defun gnus-subscribe-topics (newsgroup)
1752   (catch 'end
1753     (let (match gnus-group-change-level-function)
1754       (dolist (topic (gnus-topic-list))
1755         (when (and (setq match (cdr (assq 'subscribe
1756                                           (gnus-topic-parameters topic))))
1757                    (string-match match newsgroup))
1758           ;; Just subscribe the group.
1759           (gnus-subscribe-alphabetically newsgroup)
1760           ;; Add the group to the topic.
1761           (nconc (assoc topic gnus-topic-alist) (list newsgroup))
1762           ;; if this topic specifies a default level, use it
1763           (let ((subscribe-level (cdr (assq 'subscribe-level
1764                                             (gnus-topic-parameters topic)))))
1765             (when subscribe-level
1766                 (gnus-group-change-level newsgroup subscribe-level
1767                                          gnus-level-default-subscribed)))
1768           (throw 'end t)))
1769       nil)))
1770
1771 (provide 'gnus-topic)
1772
1773 ;;; gnus-topic.el ends here