code.delx.au - gnu-emacs/blob - lisp/mail/mh-seq.el

   1 ;;; mh-seq.el --- MH-E sequences support
   2
   3 ;; Copyright (C) 1993, 1995, 2001, 2002 Free Software Foundation, Inc.
   4
   5 ;; Author: Bill Wohler <wohler@newt.com>
   6 ;; Maintainer: Bill Wohler <wohler@newt.com>
   7 ;; Keywords: mail
   8 ;; See: mh-e.el
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software; you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation; either version 2, or (at your option)
  15 ;; any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  24 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  25 ;; Boston, MA 02111-1307, USA.
  26
  27 ;;; Commentary:
  28 ;;
  29 ;;   This tries to implement the algorithm described at:
  30 ;;     http://www.jwz.org/doc/threading.html
  31 ;;   It is also a start to implementing the IMAP Threading extension RFC. The
  32 ;;   implementation lacks the reference and subject canonicalization of the
  33 ;;   RFC.
  34 ;;
  35 ;;   In the presentation buffer, children messages are shown indented with
  36 ;;   either [ ] or < > around them. Square brackets ([ ]) denote that the
  37 ;;   algorithm can point out some headers which when taken together implies
  38 ;;   that the unindented message is an ancestor of the indented message. If
  39 ;;   no such proof exists then angles (< >) are used.
  40 ;;
  41 ;;   Some issues and problems are as follows:
  42 ;;
  43 ;;    (1) Scan truncates the fields at length 512. So longer references:
  44 ;;        headers get mutilated. The same kind of MH format string works when
  45 ;;        composing messages. Is there a way to avoid this? My scan command
  46 ;;        is as follows:
  47 ;;          scan +folder -width 10000 \
  48 ;;               -format "%(msg)\n%{message-id}\n%{references}\n%{subject}\n"
  49 ;;        I would really appreciate it if someone would help me with this.
  50 ;;
  51 ;;    (2) Implement heuristics to recognize message-id's in In-Reply-To:
  52 ;;        header. Right now it just assumes that the last text between angles
  53 ;;        (< and >) is the message-id. There is the chance that this will
  54 ;;        incorrectly use an email address like a message-id.
  55 ;;
  56 ;;    (3) Error checking of found message-id's should be done.
  57 ;;
  58 ;;    (4) Since this breaks the assumption that message indices increase as
  59 ;;        one goes down the buffer, the binary search based mh-goto-msg
  60 ;;        doesn't work. I have a simpler replacement which may be less
  61 ;;        efficient.
  62 ;;
  63 ;;    (5) Better canonicalizing for message-id and subject strings.
  64 ;;
  65
  66 ;; Internal support for MH-E package.
  67
  68 ;;; Change Log:
  69
  70 ;; $Id: mh-seq.el,v 1.71 2002/11/14 20:41:12 wohler Exp $
  71
  72 ;;; Code:
  73
  74 (require 'cl)
  75 (require 'mh-e)
  76
  77 ;; Shush the byte-compiler
  78 (defvar tool-bar-mode)
  79
  80 ;;; Data structures (used in message threading)...
  81 (defstruct (mh-thread-message (:conc-name mh-message-)
  82                               (:constructor mh-thread-make-message))
  83   (id nil)
  84   (references ())
  85   (subject "")
  86   (subject-re-p nil))
  87
  88 (defstruct (mh-thread-container (:conc-name mh-container-)
  89                                 (:constructor mh-thread-make-container))
  90   message parent children
  91   (real-child-p t))
  92
  93
  94 ;;; Internal variables:
  95 (defvar mh-last-seq-used nil
  96   "Name of seq to which a msg was last added.")
  97
  98 (defvar mh-non-seq-mode-line-annotation nil
  99   "Saved value of `mh-mode-line-annotation' when narrowed to a seq.")
 100
 101 ;;; Maps and hashes...
 102 (defvar mh-thread-id-hash nil
 103   "Hashtable used to canonicalize message-id strings.")
 104 (defvar mh-thread-subject-hash nil
 105   "Hashtable used to canonicalize subject strings.")
 106 (defvar mh-thread-id-table nil
 107   "Thread ID table maps from message-id's to message containers.")
 108 (defvar mh-thread-id-index-map nil
 109   "Table to lookup message index number from message-id.")
 110 (defvar mh-thread-index-id-map nil
 111   "Table to lookup message-id from message index.")
 112 (defvar mh-thread-scan-line-map nil
 113   "Map of message index to various parts of the scan line.")
 114 (defvar mh-thread-old-scan-line-map nil
 115   "Old map of message index to various parts of the scan line.
 116 This is the original map that is stored when the folder is narrowed.")
 117 (defvar mh-thread-subject-container-hash nil
 118   "Hashtable used to group messages by subject.")
 119 (defvar mh-thread-duplicates nil
 120   "Hashtable used to remember multiple messages with the same message-id.")
 121 (defvar mh-thread-history ()
 122   "Variable to remember the transformations to the thread tree.
 123 When new messages are added, these transformations are rewound, then the
 124 links are added from the newly seen messages. Finally the transformations are
 125 redone to get the new thread tree. This makes incremental threading easier.")
 126 (defvar mh-thread-body-width nil
 127   "Width of scan substring that contains subject and body of message.")
 128
 129 (make-variable-buffer-local 'mh-thread-id-hash)
 130 (make-variable-buffer-local 'mh-thread-subject-hash)
 131 (make-variable-buffer-local 'mh-thread-id-table)
 132 (make-variable-buffer-local 'mh-thread-id-index-map)
 133 (make-variable-buffer-local 'mh-thread-index-id-map)
 134 (make-variable-buffer-local 'mh-thread-scan-line-map)
 135 (make-variable-buffer-local 'mh-thread-old-scan-line-map)
 136 (make-variable-buffer-local 'mh-thread-subject-container-hash)
 137 (make-variable-buffer-local 'mh-thread-duplicates)
 138 (make-variable-buffer-local 'mh-thread-history)
 139
 140 (defun mh-delete-seq (sequence)
 141   "Delete the SEQUENCE."
 142   (interactive (list (mh-read-seq-default "Delete" t)))
 143   (mh-map-to-seq-msgs 'mh-notate-if-in-one-seq sequence ?  (1+ mh-cmd-note)
 144                       sequence)
 145   (mh-undefine-sequence sequence '("all"))
 146   (mh-delete-seq-locally sequence))
 147
 148 ;; Avoid compiler warnings
 149 (defvar view-exit-action)
 150
 151 (defun mh-list-sequences (folder)
 152   "List the sequences defined in FOLDER."
 153   (interactive (list (mh-prompt-for-folder "List sequences in"
 154                                            mh-current-folder t)))
 155   (let ((temp-buffer mh-temp-sequences-buffer)
 156         (seq-list mh-seq-list))
 157     (with-output-to-temp-buffer temp-buffer
 158       (save-excursion
 159         (set-buffer temp-buffer)
 160         (erase-buffer)
 161         (message "Listing sequences ...")
 162         (insert "Sequences in folder " folder ":\n")
 163         (while seq-list
 164           (let ((name (mh-seq-name (car seq-list)))
 165                 (sorted-seq-msgs
 166                  (sort (copy-sequence (mh-seq-msgs (car seq-list))) '<))
 167                 (last-col (- (window-width) 4))
 168                 name-spec)
 169             (insert (setq name-spec (format "%20s:" name)))
 170             (while sorted-seq-msgs
 171               (if (> (current-column) last-col)
 172                   (progn
 173                     (insert "\n")
 174                     (move-to-column (length name-spec))))
 175               (insert (format " %s" (car sorted-seq-msgs)))
 176               (setq sorted-seq-msgs (cdr sorted-seq-msgs)))
 177             (insert "\n"))
 178           (setq seq-list (cdr seq-list)))
 179         (goto-char (point-min))
 180         (view-mode 1)
 181         (setq view-exit-action 'kill-buffer)
 182         (message "Listing sequences...done")))))
 183
 184 (defun mh-msg-is-in-seq (message)
 185   "Display the sequences that contain MESSAGE (default: current message)."
 186   (interactive (list (mh-get-msg-num t)))
 187   (let* ((dest-folder (loop for seq in mh-refile-list
 188                                when (member message (cdr seq))
 189                                return (car seq)))
 190          (deleted-flag (unless dest-folder (member message mh-delete-list))))
 191     (message "Message %d%s is in sequences: %s"
 192              message
 193              (cond (dest-folder (format " (to be refiled to %s)" dest-folder))
 194                    (deleted-flag (format " (to be deleted)"))
 195                    (t ""))
 196              (mapconcat 'concat
 197                         (mh-list-to-string (mh-seq-containing-msg message t))
 198                         " "))))
 199
 200 (defun mh-narrow-to-seq (sequence)
 201   "Restrict display of this folder to just messages in SEQUENCE.
 202 Use \\<mh-folder-mode-map>\\[mh-widen] to undo this command."
 203   (interactive (list (mh-read-seq "Narrow to" t)))
 204   (with-mh-folder-updating (t)
 205     (cond ((mh-seq-to-msgs sequence)
 206            (mh-widen)
 207            (mh-remove-all-notation)
 208            (let ((eob (point-max))
 209                  (msg-at-cursor (mh-get-msg-num nil)))
 210              (setq mh-thread-old-scan-line-map mh-thread-scan-line-map)
 211              (setq mh-thread-scan-line-map (make-hash-table :test #'eql))
 212              (mh-copy-seq-to-eob sequence)
 213              (narrow-to-region eob (point-max))
 214              (mh-notate-user-sequences)
 215              (mh-notate-deleted-and-refiled)
 216              (mh-notate-seq 'cur mh-note-cur mh-cmd-note)
 217              (when msg-at-cursor (mh-goto-msg msg-at-cursor t t))
 218              (make-variable-buffer-local 'mh-non-seq-mode-line-annotation)
 219              (setq mh-non-seq-mode-line-annotation mh-mode-line-annotation)
 220              (setq mh-mode-line-annotation (symbol-name sequence))
 221              (mh-make-folder-mode-line)
 222              (mh-recenter nil)
 223              (if (and (boundp 'tool-bar-mode) tool-bar-mode)
 224                  (set (make-local-variable 'tool-bar-map)
 225                       mh-folder-seq-tool-bar-map))
 226              (setq mh-narrowed-to-seq sequence)
 227              (push 'widen mh-view-ops)))
 228           (t
 229            (error "No messages in sequence `%s'" (symbol-name sequence))))))
 230
 231 (defun mh-put-msg-in-seq (msg-or-seq sequence)
 232   "Add MSG-OR-SEQ (default: displayed message) to SEQUENCE.
 233 If optional prefix argument provided, then prompt for the message sequence.
 234 If variable `transient-mark-mode' is non-nil and the mark is active, then
 235 the selected region is added to the sequence."
 236   (interactive (list (cond
 237                       ((mh-mark-active-p t)
 238                        (mh-region-to-sequence (region-beginning) (region-end))
 239                        'region)
 240                       (current-prefix-arg
 241                        (mh-read-seq-default "Add messages from" t))
 242                       (t
 243                        (mh-get-msg-num t)))
 244                      (mh-read-seq-default "Add to" nil)))
 245   (if (not (mh-internal-seq sequence))
 246       (setq mh-last-seq-used sequence))
 247   (mh-add-msgs-to-seq (if (numberp msg-or-seq)
 248                           msg-or-seq
 249                         (mh-seq-to-msgs msg-or-seq))
 250                       sequence))
 251
 252 (defun mh-valid-view-change-operation-p (op)
 253   "Check if the view change operation can be performed.
 254 OP is one of 'widen and 'unthread."
 255   (cond ((eq (car mh-view-ops) op)
 256          (pop mh-view-ops))
 257         (t nil)))
 258
 259 (defun mh-widen ()
 260   "Remove restrictions from current folder, thereby showing all messages."
 261   (interactive)
 262   (let ((msg (mh-get-msg-num nil)))
 263     (when mh-narrowed-to-seq
 264       (cond ((mh-valid-view-change-operation-p 'widen) nil)
 265             ((memq 'widen mh-view-ops)
 266              (while (not (eq (car mh-view-ops) 'widen))
 267                (setq mh-view-ops (cdr mh-view-ops)))
 268              (pop mh-view-ops))
 269             (t (error "Widening is not applicable")))
 270       (when (memq 'unthread mh-view-ops)
 271         (setq mh-thread-scan-line-map mh-thread-old-scan-line-map))
 272       (with-mh-folder-updating (t)
 273         (delete-region (point-min) (point-max))
 274         (widen)
 275         (setq mh-mode-line-annotation mh-non-seq-mode-line-annotation)
 276         (mh-make-folder-mode-line))
 277       (if msg
 278           (mh-goto-msg msg t t))
 279       (mh-notate-deleted-and-refiled)
 280       (mh-notate-user-sequences)
 281       (mh-notate-seq 'cur mh-note-cur mh-cmd-note)
 282       (mh-recenter nil)))
 283   (if (and (boundp 'tool-bar-mode) tool-bar-mode)
 284       (set (make-local-variable 'tool-bar-map) mh-folder-tool-bar-map))
 285   (setq mh-narrowed-to-seq nil))
 286
 287 ;; FIXME?  We may want to clear all notations and add one for current-message
 288 ;;         and process user sequences.
 289 (defun mh-notate-deleted-and-refiled ()
 290   "Notate messages marked for deletion or refiling.
 291 Messages to be deleted are given by `mh-delete-list' while messages to be
 292 refiled are present in `mh-refile-list'."
 293   (mh-mapc #'(lambda (msg) (mh-notate msg mh-note-deleted mh-cmd-note))
 294            mh-delete-list)
 295   (mh-mapc #'(lambda (dest-msg-list)
 296                ;; foreach folder name, get the keyed sequence from mh-seq-list
 297                (let ((msg-list (cdr dest-msg-list)))
 298                  (mh-mapc #'(lambda (msg)
 299                               (mh-notate msg mh-note-refiled mh-cmd-note))
 300                           msg-list)))
 301            mh-refile-list))
 302
 303 \f
 304
 305 ;;; Commands to manipulate sequences.  Sequences are stored in an alist
 306 ;;; of the form:
 307 ;;;     ((seq-name msgs ...) (seq-name msgs ...) ...)
 308
 309 (defun mh-read-seq-default (prompt not-empty)
 310   "Read and return sequence name with default narrowed or previous sequence.
 311 PROMPT is the prompt to use when reading. If NOT-EMPTY is non-nil then a
 312 non-empty sequence is read."
 313   (mh-read-seq prompt not-empty
 314                (or mh-narrowed-to-seq
 315                    mh-last-seq-used
 316                    (car (mh-seq-containing-msg (mh-get-msg-num nil) nil)))))
 317
 318 (defun mh-read-seq (prompt not-empty &optional default)
 319   "Read and return a sequence name.
 320 Prompt with PROMPT, raise an error if the sequence is empty and the NOT-EMPTY
 321 flag is non-nil, and supply an optional DEFAULT sequence. A reply of '%'
 322 defaults to the first sequence containing the current message."
 323   (let* ((input (completing-read (format "%s %s %s" prompt "sequence:"
 324                                          (if default
 325                                              (format "[%s] " default)
 326                                              ""))
 327                                  (mh-seq-names mh-seq-list)))
 328          (seq (cond ((equal input "%")
 329                      (car (mh-seq-containing-msg (mh-get-msg-num t) nil)))
 330                     ((equal input "") default)
 331                     (t (intern input))))
 332          (msgs (mh-seq-to-msgs seq)))
 333     (if (and (null msgs) not-empty)
 334         (error "No messages in sequence `%s'" seq))
 335     seq))
 336
 337 (defun mh-seq-names (seq-list)
 338   "Return an alist containing the names of the SEQ-LIST."
 339   (mapcar (lambda (entry) (list (symbol-name (mh-seq-name entry))))
 340           seq-list))
 341
 342 (defun mh-rename-seq (sequence new-name)
 343   "Rename SEQUENCE to have NEW-NAME."
 344   (interactive (list (mh-read-seq "Old" t)
 345                      (intern (read-string "New sequence name: "))))
 346   (let ((old-seq (mh-find-seq sequence)))
 347     (or old-seq
 348         (error "Sequence %s does not exist" sequence))
 349     ;; create new sequence first, since it might raise an error.
 350     (mh-define-sequence new-name (mh-seq-msgs old-seq))
 351     (mh-undefine-sequence sequence (mh-seq-msgs old-seq))
 352     (rplaca old-seq new-name)))
 353
 354 (defun mh-map-to-seq-msgs (func seq &rest args)
 355 "Invoke the FUNC at each message in the SEQ.
 356 The remaining ARGS are passed as arguments to FUNC."
 357   (save-excursion
 358     (let ((msgs (mh-seq-to-msgs seq)))
 359       (while msgs
 360         (if (mh-goto-msg (car msgs) t t)
 361             (apply func (car msgs) args))
 362         (setq msgs (cdr msgs))))))
 363
 364 (defun mh-notate-seq (seq notation offset)
 365   "Mark the scan listing.
 366 All messages in SEQ are marked with NOTATION at OFFSET from the beginning of
 367 the line."
 368   (mh-map-to-seq-msgs 'mh-notate seq notation offset))
 369
 370 (defun mh-add-to-sequence (seq msgs)
 371   "The sequence SEQ is augmented with the messages in MSGS."
 372   ;; Add to a SEQUENCE each message the list of MSGS.
 373   (if (not (mh-folder-name-p seq))
 374       (if msgs
 375           (apply 'mh-exec-cmd "mark" mh-current-folder "-add"
 376                  "-sequence" (symbol-name seq)
 377                  (mh-coalesce-msg-list msgs)))))
 378
 379 ;; This has a tricky bug. mh-map-to-seq-msgs uses mh-goto-msg, which assumes
 380 ;; that the folder buffer is sorted. However in this case that assumption
 381 ;; doesn't hold. So we will do this the dumb way.
 382 ;(defun mh-copy-seq-to-point (seq location)
 383 ;  ;; Copy the scan listing of the messages in SEQUENCE to after the point
 384 ;  ;; LOCATION in the current buffer.
 385 ;  (mh-map-to-seq-msgs 'mh-copy-line-to-point seq location))
 386
 387 (defun mh-copy-seq-to-eob (seq)
 388   "Copy SEQ to the end of the buffer."
 389   ;; It is quite involved to write something which will work at any place in
 390   ;; the buffer, so we will write something which works only at the end of
 391   ;; the buffer. If we ever need to insert sequences in the middle of the
 392   ;; buffer, this will need to be fixed.
 393   (save-excursion
 394     (let* ((msgs (mh-seq-to-msgs seq))
 395            (coalesced-msgs (mh-coalesce-msg-list msgs)))
 396       (goto-char (point-max))
 397       (save-restriction
 398         (narrow-to-region (point) (point))
 399         (mh-regenerate-headers coalesced-msgs t)
 400         (when (memq 'unthread mh-view-ops)
 401           ;; Populate restricted scan-line map
 402           (goto-char (point-min))
 403           (while (not (eobp))
 404             (setf (gethash (mh-get-msg-num nil) mh-thread-scan-line-map)
 405                   (mh-thread-parse-scan-line))
 406             (forward-line))
 407           ;; Remove scan lines and read results from pre-computed thread tree
 408           (delete-region (point-min) (point-max))
 409           (let ((thread-tree (mh-thread-generate mh-current-folder ()))
 410                 (mh-thread-body-width
 411                   (- (window-width) mh-cmd-note
 412                      (1- mh-scan-field-subject-start-offset))))
 413             (mh-thread-generate-scan-lines thread-tree -2)))))))
 414
 415 (defun mh-copy-line-to-point (msg location)
 416   "Copy current message line to a specific location.
 417 The argument MSG is not used. The message in the current line is copied to
 418 LOCATION."
 419   ;; msg is not used?
 420   ;; Copy the current line to the LOCATION in the current buffer.
 421   (beginning-of-line)
 422   (save-excursion
 423     (let ((beginning-of-line (point))
 424           end)
 425       (forward-line 1)
 426       (setq end (point))
 427       (goto-char location)
 428       (insert-buffer-substring (current-buffer) beginning-of-line end))))
 429
 430 (defun mh-region-to-sequence (begin end)
 431   "Define sequence 'region as the messages between point and mark.
 432 When called programmatically, use arguments BEGIN and END to define region."
 433   (interactive "r")
 434   (mh-delete-seq-locally 'region)
 435   (save-excursion
 436     ;; If end is end of buffer back up one position
 437     (setq end (if (equal end (point-max)) (1- end) end))
 438     (goto-char begin)
 439     (while (<= (point) end)
 440       (mh-add-msgs-to-seq (mh-get-msg-num t) 'region t)
 441       (forward-line 1))))
 442
 443 \f
 444
 445 ;;; Commands to handle new 'subject sequence.
 446 ;;; Or "Poor man's threading" by psg.
 447
 448 (defun mh-subject-to-sequence (all)
 449   "Put all following messages with same subject in sequence 'subject.
 450 If arg ALL is t, move to beginning of folder buffer to collect all messages.
 451 If arg ALL is nil, collect only messages fron current one on forward.
 452
 453 Return number of messages put in the sequence:
 454
 455  nil -> there was no subject line.
 456  0   -> there were no later messages with the same subject (sequence not made)
 457  >1  -> the total number of messages including current one."
 458   (if (not (eq major-mode 'mh-folder-mode))
 459       (error "Not in a folder buffer"))
 460   (save-excursion
 461     (beginning-of-line)
 462     (if (or (not (looking-at mh-scan-subject-regexp))
 463             (not (match-string 3))
 464             (string-equal "" (match-string 3)))
 465         (progn (message "No subject line.")
 466                nil)
 467       (let ((subject (match-string-no-properties 3))
 468             (list))
 469         (if (> (length subject) 41)
 470             (setq subject (substring subject 0 41)))
 471         (save-excursion
 472           (if all
 473               (goto-char (point-min)))
 474           (while (re-search-forward mh-scan-subject-regexp nil t)
 475             (let ((this-subject (match-string-no-properties 3)))
 476               (if (> (length this-subject) 41)
 477                   (setq this-subject (substring this-subject 0 41)))
 478               (if (string-equal this-subject subject)
 479                   (setq list (cons (mh-get-msg-num t) list))))))
 480         (cond
 481          (list
 482           ;; If we created a new sequence, add the initial message to it too.
 483           (if (not (member (mh-get-msg-num t) list))
 484               (setq list (cons (mh-get-msg-num t) list)))
 485           (if (member '("subject") (mh-seq-names mh-seq-list))
 486               (mh-delete-seq 'subject))
 487           ;; sort the result into a sequence
 488           (let ((sorted-list (sort (copy-sequence list) 'mh-lessp)))
 489             (while sorted-list
 490               (mh-add-msgs-to-seq (car sorted-list) 'subject nil)
 491               (setq sorted-list (cdr sorted-list)))
 492             (safe-length list)))
 493          (t
 494           0))))))
 495
 496 (defun mh-narrow-to-subject ()
 497   "Narrow to a sequence containing all following messages with same subject."
 498   (interactive)
 499   (let ((num (mh-get-msg-num nil))
 500         (count (mh-subject-to-sequence t)))
 501     (cond
 502      ((not count)                       ; No subject line, delete msg anyway
 503       nil)
 504      ((= 0 count)                       ; No other msgs, delete msg anyway.
 505       (message "No other messages with same Subject following this one.")
 506       nil)
 507      (t                                 ; We have a subject sequence.
 508       (message "Found %d messages for subject sequence." count)
 509       (mh-narrow-to-seq 'subject)
 510       (if (numberp num)
 511           (mh-goto-msg num t t))))))
 512
 513 (defun mh-delete-subject ()
 514   "Mark all following messages with same subject to be deleted.
 515 This puts the messages in a sequence named subject.  You can undo the last
 516 deletion marks using `mh-undo' with a prefix argument and then specifying the
 517 subject sequence."
 518   (interactive)
 519   (let ((count (mh-subject-to-sequence nil)))
 520     (cond
 521      ((not count)                       ; No subject line, delete msg anyway
 522       (mh-delete-msg (mh-get-msg-num t)))
 523      ((= 0 count)                       ; No other msgs, delete msg anyway.
 524       (message "No other messages with same Subject following this one.")
 525       (mh-delete-msg (mh-get-msg-num t)))
 526      (t                                 ; We have a subject sequence.
 527       (message "Marked %d messages for deletion" count)
 528       (mh-delete-msg 'subject)))))
 529
 530 ;;; Message threading:
 531
 532 (defun mh-thread-initialize ()
 533   "Make hash tables, otherwise clear them."
 534   (cond
 535     (mh-thread-id-hash
 536      (clrhash mh-thread-id-hash)
 537      (clrhash mh-thread-subject-hash)
 538      (clrhash mh-thread-id-table)
 539      (clrhash mh-thread-id-index-map)
 540      (clrhash mh-thread-index-id-map)
 541      (clrhash mh-thread-scan-line-map)
 542      (clrhash mh-thread-subject-container-hash)
 543      (clrhash mh-thread-duplicates)
 544      (setq mh-thread-history ()))
 545     (t (setq mh-thread-id-hash (make-hash-table :test #'equal))
 546        (setq mh-thread-subject-hash (make-hash-table :test #'equal))
 547        (setq mh-thread-id-table (make-hash-table :test #'eq))
 548        (setq mh-thread-id-index-map (make-hash-table :test #'eq))
 549        (setq mh-thread-index-id-map (make-hash-table :test #'eql))
 550        (setq mh-thread-scan-line-map (make-hash-table :test #'eql))
 551        (setq mh-thread-subject-container-hash (make-hash-table :test #'eq))
 552        (setq mh-thread-duplicates (make-hash-table :test #'eq))
 553        (setq mh-thread-history ()))))
 554
 555 (defsubst mh-thread-id-container (id)
 556   "Given ID, return the corresponding container in `mh-thread-id-table'.
 557 If no container exists then a suitable container is created and the id-table
 558 is updated."
 559   (when (not id)
 560     (error "1"))
 561   (or (gethash id mh-thread-id-table)
 562       (setf (gethash id mh-thread-id-table)
 563             (let ((message (mh-thread-make-message :id id)))
 564               (mh-thread-make-container :message message)))))
 565
 566 (defsubst mh-thread-remove-parent-link (child)
 567   "Remove parent link of CHILD if it exists."
 568   (let* ((child-container (if (mh-thread-container-p child)
 569                               child (mh-thread-id-container child)))
 570          (parent-container (mh-container-parent child-container)))
 571     (when parent-container
 572       (setf (mh-container-children parent-container)
 573             (remove* child-container (mh-container-children parent-container)
 574                      :test #'eq))
 575       (setf (mh-container-parent child-container) nil))))
 576
 577 (defsubst mh-thread-add-link (parent child &optional at-end-p)
 578   "Add links so that PARENT becomes a parent of CHILD.
 579 Doesn't make any changes if CHILD is already an ancestor of PARENT. If
 580 optional argument AT-END-P is non-nil, the CHILD is added to the end of the
 581 children list of PARENT."
 582   (let ((parent-container (cond ((null parent) nil)
 583                                 ((mh-thread-container-p parent) parent)
 584                                 (t (mh-thread-id-container parent))))
 585         (child-container (if (mh-thread-container-p child)
 586                              child (mh-thread-id-container child))))
 587     (when (and parent-container
 588                (not (mh-thread-ancestor-p child-container parent-container))
 589                (not (mh-thread-ancestor-p parent-container child-container)))
 590       (mh-thread-remove-parent-link child-container)
 591       (cond ((not at-end-p)
 592              (push child-container (mh-container-children parent-container)))
 593             ((null (mh-container-children parent-container))
 594              (push child-container (mh-container-children parent-container)))
 595             (t (let ((last-child (mh-container-children parent-container)))
 596                  (while (cdr last-child)
 597                    (setq last-child (cdr last-child)))
 598                  (setcdr last-child (cons child-container nil)))))
 599       (setf (mh-container-parent child-container) parent-container))
 600     (unless parent-container
 601       (mh-thread-remove-parent-link child-container))))
 602
 603 (defun mh-thread-ancestor-p (ancestor successor)
 604   "Return t if ANCESTOR is really an ancestor of SUCCESSOR and nil otherwise.
 605 In the limit, the function returns t if ANCESTOR and SUCCESSOR are the same
 606 containers."
 607   (block nil
 608     (while successor
 609       (when (eq ancestor successor) (return t))
 610       (setq successor (mh-container-parent successor)))
 611     nil))
 612
 613 (defsubst mh-thread-get-message-container (message)
 614   "Return container which has MESSAGE in it.
 615 If there is no container present then a new container is allocated."
 616   (let* ((id (mh-message-id message))
 617          (container (gethash id mh-thread-id-table)))
 618     (cond (container (setf (mh-container-message container) message)
 619                      container)
 620           (t (setf (gethash id mh-thread-id-table)
 621                    (mh-thread-make-container :message message))))))
 622
 623 (defsubst mh-thread-get-message (id subject-re-p subject refs)
 624   "Return appropriate message.
 625 Otherwise update message already present to have the proper ID, SUBJECT-RE-P,
 626 SUBJECT and REFS fields."
 627   (let* ((container (gethash id mh-thread-id-table))
 628          (message (if container (mh-container-message container) nil)))
 629     (cond (message
 630            (setf (mh-message-subject-re-p message) subject-re-p)
 631            (setf (mh-message-subject message) subject)
 632            (setf (mh-message-id message) id)
 633            (setf (mh-message-references message) refs)
 634            message)
 635           (container
 636            (setf (mh-container-message container)
 637                  (mh-thread-make-message :subject subject
 638                                          :subject-re-p subject-re-p
 639                                          :id id :references refs)))
 640           (t (let ((message (mh-thread-make-message
 641                              :subject subject
 642                              :subject-re-p subject-re-p
 643                              :id id :references refs)))
 644                (prog1 message
 645                  (mh-thread-get-message-container message)))))))
 646
 647 (defsubst mh-thread-canonicalize-id (id)
 648   "Produce canonical string representation for ID.
 649 This allows cheap string comparison with EQ."
 650   (or (and (equal id "") (copy-sequence ""))
 651       (gethash id mh-thread-id-hash)
 652       (setf (gethash id mh-thread-id-hash) id)))
 653
 654 (defsubst mh-thread-prune-subject (subject)
 655   "Prune leading Re:'s, Fwd:'s etc. and trailing (fwd)'s from SUBJECT.
 656 If the result after pruning is not the empty string then it is canonicalized
 657 so that subjects can be tested for equality with eq. This is done so that all
 658 the messages without a subject are not put into a single thread."
 659   (let ((case-fold-search t)
 660         (subject-pruned-flag nil))
 661     ;; Prune subject leader
 662     (while (or (string-match "^[ \t]*\\(re\\|fwd?\\)\\(\\[[0-9]*\\]\\)?:[ \t]*"
 663                              subject)
 664                (string-match "^[ \t]*\\[[^\\]][ \t]*" subject))
 665       (setq subject-pruned-flag t)
 666       (setq subject (substring subject (match-end 0))))
 667     ;; Prune subject trailer
 668     (while (or (string-match "(fwd)$" subject)
 669                (string-match "[ \t]+$" subject))
 670       (setq subject-pruned-flag t)
 671       (setq subject (substring subject 0 (match-beginning 0))))
 672     ;; Canonicalize subject only if it is non-empty
 673     (cond ((equal subject "") (values subject subject-pruned-flag))
 674           (t (values
 675               (or (gethash subject mh-thread-subject-hash)
 676                   (setf (gethash subject mh-thread-subject-hash) subject))
 677               subject-pruned-flag)))))
 678
 679 (defun mh-thread-container-subject (container)
 680   "Return the subject of CONTAINER.
 681 If CONTAINER is empty return the subject info of one of its children."
 682   (cond ((and (mh-container-message container)
 683               (mh-message-id (mh-container-message container)))
 684          (mh-message-subject (mh-container-message container)))
 685         (t (block nil
 686              (dolist (kid (mh-container-children container))
 687                (when (and (mh-container-message kid)
 688                           (mh-message-id (mh-container-message kid)))
 689                  (let ((kid-message (mh-container-message kid)))
 690                    (return (mh-message-subject kid-message)))))
 691              (error "This can't happen!")))))
 692
 693 (defun mh-thread-rewind-pruning ()
 694   "Restore the thread tree to its state before pruning."
 695   (while mh-thread-history
 696     (let ((action (pop mh-thread-history)))
 697       (cond ((eq (car action) 'DROP)
 698              (mh-thread-remove-parent-link (cadr action))
 699              (mh-thread-add-link (caddr action) (cadr action)))
 700             ((eq (car action) 'PROMOTE)
 701              (let ((node (cadr action))
 702                    (parent (caddr action))
 703                    (children (cdddr action)))
 704                (dolist (child children)
 705                  (mh-thread-remove-parent-link child)
 706                  (mh-thread-add-link node child))
 707                (mh-thread-add-link parent node)))
 708             ((eq (car action) 'SUBJECT)
 709              (let ((node (cadr action)))
 710                (mh-thread-remove-parent-link node)
 711                (setf (mh-container-real-child-p node) t)))))))
 712
 713 (defun mh-thread-prune-containers (roots)
 714 "Prune empty containers in the containers ROOTS."
 715   (let ((dfs-ordered-nodes ())
 716         (work-list roots))
 717     (while work-list
 718       (let ((node (pop work-list)))
 719         (dolist (child (mh-container-children node))
 720           (push child work-list))
 721         (push node dfs-ordered-nodes)))
 722     (while dfs-ordered-nodes
 723       (let ((node (pop dfs-ordered-nodes)))
 724         (cond ((gethash (mh-message-id (mh-container-message node))
 725                         mh-thread-id-index-map)
 726                ;; Keep it
 727                (setf (mh-container-children node)
 728                      (mh-thread-sort-containers (mh-container-children node))))
 729               ((and (mh-container-children node)
 730                     (or (null (cdr (mh-container-children node)))
 731                         (mh-container-parent node)))
 732                ;; Promote kids
 733                (let ((children ()))
 734                  (dolist (kid (mh-container-children node))
 735                    (mh-thread-remove-parent-link kid)
 736                    (mh-thread-add-link (mh-container-parent node) kid)
 737                    (push kid children))
 738                  (push `(PROMOTE ,node ,(mh-container-parent node) ,@children)
 739                        mh-thread-history)
 740                  (mh-thread-remove-parent-link node)))
 741               ((mh-container-children node)
 742                ;; Promote the first orphan to parent and add the other kids as
 743                ;; his children
 744                (setf (mh-container-children node)
 745                      (mh-thread-sort-containers (mh-container-children node)))
 746                (let ((new-parent (car (mh-container-children node)))
 747                      (other-kids (cdr (mh-container-children node))))
 748                  (mh-thread-remove-parent-link new-parent)
 749                  (dolist (kid other-kids)
 750                    (mh-thread-remove-parent-link kid)
 751                    (setf (mh-container-real-child-p kid) nil)
 752                    (mh-thread-add-link new-parent kid t))
 753                  (push `(PROMOTE ,node ,(mh-container-parent node)
 754                                  ,new-parent ,@other-kids)
 755                        mh-thread-history)
 756                  (mh-thread-remove-parent-link node)))
 757               (t
 758                ;; Drop it
 759                (push `(DROP ,node ,(mh-container-parent node))
 760                      mh-thread-history)
 761                (mh-thread-remove-parent-link node)))))
 762     (let ((results ()))
 763       (maphash #'(lambda (k v)
 764                    (declare (ignore k))
 765                    (when (and (null (mh-container-parent v))
 766                               (gethash (mh-message-id (mh-container-message v))
 767                                        mh-thread-id-index-map))
 768                      (push v results)))
 769                mh-thread-id-table)
 770       (mh-thread-sort-containers results))))
 771
 772 (defun mh-thread-sort-containers (containers)
 773   "Sort a list of message CONTAINERS to be in ascending order wrt index."
 774   (sort containers
 775         #'(lambda (x y)
 776             (when (and (mh-container-message x) (mh-container-message y))
 777               (let* ((id-x (mh-message-id (mh-container-message x)))
 778                      (id-y (mh-message-id (mh-container-message y)))
 779                      (index-x (gethash id-x mh-thread-id-index-map))
 780                      (index-y (gethash id-y mh-thread-id-index-map)))
 781                 (and (integerp index-x) (integerp index-y)
 782                      (< index-x index-y)))))))
 783
 784 (defsubst mh-thread-group-by-subject (roots)
 785   "Group the set of message containers, ROOTS based on subject.
 786 Bug: Check for and make sure that something without Re: is made the parent in
 787 preference to something that has it."
 788   (clrhash mh-thread-subject-container-hash)
 789   (let ((results ()))
 790     (dolist (root roots)
 791       (let* ((subject (mh-thread-container-subject root))
 792              (parent (gethash subject mh-thread-subject-container-hash)))
 793         (cond (parent (mh-thread-remove-parent-link root)
 794                       (mh-thread-add-link parent root t)
 795                       (setf (mh-container-real-child-p root) nil)
 796                       (push `(SUBJECT ,root) mh-thread-history))
 797               (t
 798                (setf (gethash subject mh-thread-subject-container-hash) root)
 799                (push root results)))))
 800     (nreverse results)))
 801
 802 (defsubst mh-thread-process-in-reply-to (reply-to-header)
 803   "Extract message id's from REPLY-TO-HEADER.
 804 Ideally this should have some regexp which will try to guess if a string
 805 between < and > is a message id and not an email address. For now it will
 806 take the last string inside angles."
 807   (let ((end (search ">" reply-to-header :from-end t)))
 808     (when (numberp end)
 809       (let ((begin (search "<" reply-to-header :from-end t :end2 end)))
 810         (when (numberp begin)
 811           (list (substring reply-to-header begin (1+ end))))))))
 812
 813 (defun mh-thread-set-tables (folder)
 814   "Use the tables of FOLDER in current buffer."
 815   (flet ((mh-get-table (symbol)
 816            (save-excursion (set-buffer folder) (symbol-value symbol))))
 817     (setq mh-thread-id-hash (mh-get-table 'mh-thread-id-hash))
 818     (setq mh-thread-subject-hash (mh-get-table 'mh-thread-subject-hash))
 819     (setq mh-thread-id-table (mh-get-table 'mh-thread-id-table))
 820     (setq mh-thread-id-index-map (mh-get-table 'mh-thread-id-index-map))
 821     (setq mh-thread-index-id-map (mh-get-table 'mh-thread-index-id-map))
 822     (setq mh-thread-scan-line-map (mh-get-table 'mh-thread-scan-line-map))
 823     (setq mh-thread-subject-container-hash
 824           (mh-get-table 'mh-thread-subject-container-hash))
 825     (setq mh-thread-duplicates (mh-get-table 'mh-thread-duplicates))
 826     (setq mh-thread-history (mh-get-table 'mh-thread-history))))
 827
 828 (defsubst mh-thread-update-id-index-maps (id index)
 829   "Message with id, ID is the message in INDEX.
 830 The function also checks for duplicate messages (that is multiple messages
 831 with the same ID). These messages are put in the `mh-thread-duplicates' hash
 832 table."
 833   (let ((old-index (gethash id mh-thread-id-index-map)))
 834     (when old-index (push old-index (gethash id mh-thread-duplicates)))
 835     (setf (gethash id mh-thread-id-index-map) index)
 836     (setf (gethash index mh-thread-index-id-map) id)))
 837
 838 \f
 839
 840 ;;; Generate Threads...
 841
 842 (defun mh-thread-generate (folder msg-list)
 843   "Scan FOLDER to get info for threading.
 844 Only information about messages in MSG-LIST are added to the tree."
 845   (save-excursion
 846     (set-buffer (get-buffer-create "*mh-thread*"))
 847     (mh-thread-set-tables folder)
 848     (erase-buffer)
 849     (when msg-list
 850       (apply
 851        #'call-process (expand-file-name mh-scan-prog mh-progs) nil '(t nil) nil
 852        "-width" "10000" "-format"
 853        "%(msg)\n%{message-id}\n%{references}\n%{in-reply-to}\n%{subject}\n"
 854        (mapcar #'(lambda (x) (format "%s" x)) msg-list)))
 855     (goto-char (point-min))
 856     (let ((roots ())
 857           (case-fold-search t))
 858       (block nil
 859         (while (not (eobp))
 860           (block process-message
 861             (let* ((index-line
 862                      (prog1 (buffer-substring (point) (line-end-position))
 863                        (forward-line)))
 864                    (index (car (read-from-string index-line)))
 865                    (id (prog1 (buffer-substring (point) (line-end-position))
 866                          (forward-line)))
 867                    (refs (prog1 (buffer-substring (point) (line-end-position))
 868                            (forward-line)))
 869                    (in-reply-to (prog1 (buffer-substring (point)
 870                                                          (line-end-position))
 871                                   (forward-line)))
 872                    (subject (prog1
 873                                 (buffer-substring (point) (line-end-position))
 874                               (forward-line)))
 875                    (subject-re-p nil))
 876               (unless (gethash index mh-thread-scan-line-map)
 877                 (return-from process-message))
 878               (unless (integerp index) (return)) ;Error message here
 879               (multiple-value-setq (subject subject-re-p)
 880                 (mh-thread-prune-subject subject))
 881               (setq in-reply-to (mh-thread-process-in-reply-to in-reply-to))
 882               (setq refs (append (split-string refs) in-reply-to))
 883               (setq id (mh-thread-canonicalize-id id))
 884               (mh-thread-update-id-index-maps id index)
 885               (setq refs (mapcar #'mh-thread-canonicalize-id refs))
 886               (mh-thread-get-message id subject-re-p subject refs)
 887               (do ((ancestors refs (cdr ancestors)))
 888                   ((null (cdr ancestors))
 889                    (when (car ancestors)
 890                      (mh-thread-remove-parent-link id)
 891                      (mh-thread-add-link (car ancestors) id)))
 892                 (mh-thread-add-link (car ancestors) (cadr ancestors)))))))
 893       (maphash #'(lambda (k v)
 894                    (declare (ignore k))
 895                    (when (null (mh-container-parent v))
 896                      (push v roots)))
 897                mh-thread-id-table)
 898       (setq roots (mh-thread-prune-containers roots))
 899       (prog1 (setq roots (mh-thread-group-by-subject roots))
 900         (let ((history mh-thread-history))
 901           (set-buffer folder)
 902           (setq mh-thread-history history))))))
 903
 904 (defun mh-thread-inc (folder start-point)
 905   "Update thread tree for FOLDER.
 906 All messages after START-POINT are added to the thread tree."
 907   (mh-thread-rewind-pruning)
 908   (goto-char start-point)
 909   (let ((msg-list ()))
 910     (while (not (eobp))
 911       (let ((index (mh-get-msg-num nil)))
 912         (push index msg-list)
 913         (setf (gethash index mh-thread-scan-line-map)
 914               (mh-thread-parse-scan-line))
 915         (forward-line)))
 916     (let ((thread-tree (mh-thread-generate folder msg-list))
 917           (buffer-read-only nil)
 918           (old-buffer-modified-flag (buffer-modified-p)))
 919       (delete-region (point-min) (point-max))
 920       (let ((mh-thread-body-width (- (window-width) mh-cmd-note
 921                                      (1- mh-scan-field-subject-start-offset))))
 922         (mh-thread-generate-scan-lines thread-tree -2))
 923       (mh-notate-user-sequences)
 924       (mh-notate-deleted-and-refiled)
 925       (mh-notate-seq 'cur mh-note-cur mh-cmd-note)
 926       (set-buffer-modified-p old-buffer-modified-flag))))
 927
 928 (defun mh-thread-generate-scan-lines (tree level)
 929   "Generate scan lines.
 930 TREE is the hierarchical tree of messages, SCAN-LINE-MAP maps message indices
 931 to the corresponding scan lines and LEVEL used to determine indentation of
 932 the message."
 933   (cond ((null tree) nil)
 934         ((mh-thread-container-p tree)
 935          (let* ((message (mh-container-message tree))
 936                 (id (mh-message-id message))
 937                 (index (gethash id mh-thread-id-index-map))
 938                 (duplicates (gethash id mh-thread-duplicates))
 939                 (new-level (+ level 2))
 940                 (dupl-flag t)
 941                 (increment-level-flag nil))
 942            (dolist (scan-line (mapcar (lambda (x)
 943                                         (gethash x mh-thread-scan-line-map))
 944                                       (reverse (cons index duplicates))))
 945              (when scan-line
 946                (insert (car scan-line)
 947                        (format (format "%%%ss"
 948                                        (if dupl-flag level new-level)) "")
 949                        (if (and (mh-container-real-child-p tree) dupl-flag)
 950                            "[" "<")
 951                        (cadr scan-line)
 952                        (if (and (mh-container-real-child-p tree) dupl-flag)
 953                            "]" ">")
 954                        (truncate-string-to-width
 955                         (caddr scan-line) (- mh-thread-body-width
 956                                              (if dupl-flag level new-level)))
 957                        "\n")
 958                (setq increment-level-flag t)
 959                (setq dupl-flag nil)))
 960            (unless increment-level-flag (setq new-level level))
 961            (dolist (child (mh-container-children tree))
 962              (mh-thread-generate-scan-lines child new-level))))
 963         (t (let ((nlevel (+ level 2)))
 964              (dolist (ch tree)
 965                (mh-thread-generate-scan-lines ch nlevel))))))
 966
 967 ;; Another and may be better approach would be to generate all the info from
 968 ;; the scan which generates the threading info. For now this will have to do.
 969 (defun mh-thread-parse-scan-line (&optional string)
 970   "Parse a scan line.
 971 If optional argument STRING is given then that is assumed to be the scan line.
 972 Otherwise uses the line at point as the scan line to parse."
 973   (let* ((string (or string
 974                      (buffer-substring-no-properties (line-beginning-position)
 975                                                      (line-end-position))))
 976          (first-string (substring string 0 (+ mh-cmd-note 8))))
 977     (setf (elt first-string mh-cmd-note) ? )
 978     (when (equal (elt first-string (1+ mh-cmd-note)) (elt mh-note-seq 0))
 979       (setf (elt first-string (1+ mh-cmd-note)) ? ))
 980     (list first-string
 981           (substring string
 982                      (+ mh-cmd-note mh-scan-field-from-start-offset)
 983                      (+ mh-cmd-note mh-scan-field-from-end-offset -2))
 984           (substring string (+ mh-cmd-note mh-scan-field-from-end-offset))
 985           string)))
 986
 987 (defun mh-thread-add-spaces (count)
 988   "Add COUNT spaces to each scan line in `mh-thread-scan-line-map'."
 989   (let ((spaces (format (format "%%%ss" count) "")))
 990     (while (not (eobp))
 991       (let* ((msg-num (mh-get-msg-num nil))
 992              (old-line (nth 3 (gethash msg-num mh-thread-scan-line-map))))
 993         (setf (gethash msg-num mh-thread-scan-line-map)
 994               (mh-thread-parse-scan-line (format "%s%s" spaces old-line))))
 995       (forward-line 1))))
 996
 997 (defun mh-thread-folder ()
 998   "Generate thread view of folder."
 999   (message "Threading %s..." (buffer-name))
1000   (mh-thread-initialize)
1001   (goto-char (point-min))
1002   (while (not (eobp))
1003     (setf (gethash (mh-get-msg-num nil) mh-thread-scan-line-map)
1004           (mh-thread-parse-scan-line))
1005     (forward-line))
1006   (let* ((range (format "%s-%s" mh-first-msg-num mh-last-msg-num))
1007          (thread-tree (mh-thread-generate (buffer-name) (list range)))
1008          (buffer-read-only nil)
1009          (old-buffer-modified-p (buffer-modified-p)))
1010     (delete-region (point-min) (point-max))
1011     (let ((mh-thread-body-width (- (window-width) mh-cmd-note
1012                                    (1- mh-scan-field-subject-start-offset))))
1013       (mh-thread-generate-scan-lines thread-tree -2))
1014     (mh-notate-user-sequences)
1015     (mh-notate-deleted-and-refiled)
1016     (mh-notate-seq 'cur mh-note-cur mh-cmd-note)
1017     (set-buffer-modified-p old-buffer-modified-p)
1018     (message "Threading %s...done" (buffer-name))))
1019
1020 (defun mh-toggle-threads ()
1021   "Toggle threaded view of folder.
1022 The conversion of normal view to threaded view is exact, that is the same
1023 messages are displayed in the folder buffer before and after threading. However
1024 the conversion from threaded view to normal view is inexact. So more messages
1025 than were originally present may be shown as a result."
1026   (interactive)
1027   (let ((msg-at-point (mh-get-msg-num nil)))
1028     (cond ((and (memq 'unthread mh-view-ops) mh-narrowed-to-seq)
1029            (unless (mh-valid-view-change-operation-p 'unthread)
1030              (error "Can't unthread folder"))
1031            (mh-scan-folder mh-current-folder
1032                            (format "%s" mh-narrowed-to-seq)
1033                            t))
1034           ((memq 'unthread mh-view-ops)
1035            (unless (mh-valid-view-change-operation-p 'unthread)
1036              (error "Can't unthread folder"))
1037            (mh-scan-folder mh-current-folder
1038                            (format "%s-%s" mh-first-msg-num mh-last-msg-num)
1039                            t))
1040           (t (mh-thread-folder)
1041              (push 'unthread mh-view-ops)))
1042     (when msg-at-point (mh-goto-msg msg-at-point t t))
1043     (mh-recenter nil)))
1044
1045 (defun mh-thread-forget-message (index)
1046   "Forget the message INDEX from the threading tables."
1047   (let* ((id (gethash index mh-thread-index-id-map))
1048          (id-index (gethash id mh-thread-id-index-map))
1049          (duplicates (gethash id mh-thread-duplicates)))
1050     (remhash index mh-thread-index-id-map)
1051     (cond ((and (eql index id-index) (null duplicates))
1052            (remhash id mh-thread-id-index-map))
1053           ((eql index id-index)
1054            (setf (gethash id mh-thread-id-index-map) (car duplicates))
1055            (setf (gethash (car duplicates) mh-thread-index-id-map) id)
1056            (setf (gethash id mh-thread-duplicates) (cdr duplicates)))
1057           (t
1058            (setf (gethash id mh-thread-duplicates)
1059                  (remove index duplicates))))))
1060
1061 (provide 'mh-seq)
1062
1063 ;;; Local Variables:
1064 ;;; sentence-end-double-space: nil
1065 ;;; End:
1066
1067 ;;; mh-seq.el ends here