lisp/mh-e/mh-thread.el

   1 ;;; mh-thread.el --- MH-E threading support
   2
   3 ;; Copyright (C) 2002-2004, 2006-2014 Free Software Foundation, Inc.
   4
   5 ;; Author: Satyaki Das <satyaki@theforce.stanford.edu>
   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 3 of the License, or
  15 ;; (at your option) 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.  If not, see <http://www.gnu.org/licenses/>.
  24
  25 ;;; Commentary:
  26
  27 ;; The threading portion of this files tries to implement the
  28 ;; algorithm described at:
  29 ;;   http://www.jwz.org/doc/threading.html
  30 ;; It also begins to implement the threading section of the IMAP -
  31 ;; SORT and THREAD Extensions RFC at:
  32 ;;   http://tools.ietf.org/html/rfc5256
  33 ;; The implementation lacks the reference and subject canonicalization
  34 ;; of the RFC.
  35
  36 ;; In the presentation buffer, children messages are shown indented
  37 ;; with either [ ] or < > around them. Square brackets ([ ]) denote
  38 ;; that the algorithm can point out some headers which when taken
  39 ;; together implies that the unindented message is an ancestor of the
  40 ;; indented message. If no such proof exists then angles (< >) are
  41 ;; used.
  42
  43 ;; If threading is slow on your machine, compile this file. Of all the
  44 ;; files in MH-E, this one really benefits from compilation.
  45
  46 ;; Some issues and problems are as follows:
  47
  48 ;;  (1) Scan truncates the fields at length 512. So longer
  49 ;;      references: headers get mutilated. The same kind of MH
  50 ;;      format string works when composing messages. Is there a way
  51 ;;      to avoid this? My scan command is as follows:
  52 ;;        scan +folder -width 10000 \
  53 ;;             -format "%(msg)\n%{message-id}\n%{references}\n%{subject}\n"
  54 ;;      I would really appreciate it if someone would help me with this.
  55
  56 ;;  (2) Implement heuristics to recognize message identifiers in
  57 ;;      In-Reply-To: header. Right now it just assumes that the last
  58 ;;      text between angles (< and >) is the message identifier.
  59 ;;      There is the chance that this will incorrectly use an email
  60 ;;      address like a message identifier.
  61
  62 ;;  (3) Error checking of found message identifiers should be done.
  63
  64 ;;  (4) Since this breaks the assumption that message indices
  65 ;;      increase as one goes down the buffer, the binary search
  66 ;;      based mh-goto-msg doesn't work. I have a simpler replacement
  67 ;;      which may be less efficient.
  68
  69 ;;  (5) Better canonicalizing for message identifier and subject
  70 ;;      strings.
  71
  72 ;;; Change Log:
  73
  74 ;;; Code:
  75
  76 (require 'mh-e)
  77 (require 'mh-scan)
  78
  79 (mh-defstruct (mh-thread-message (:conc-name mh-message-)
  80                                  (:constructor mh-thread-make-message))
  81   (id nil)
  82   (references ())
  83   (subject "")
  84   (subject-re-p nil))
  85
  86 (mh-defstruct (mh-thread-container (:conc-name mh-container-)
  87                                    (:constructor mh-thread-make-container))
  88   message parent children
  89   (real-child-p t))
  90
  91 (defvar mh-thread-id-hash nil
  92   "Hashtable used to canonicalize message identifiers.")
  93 (make-variable-buffer-local 'mh-thread-id-hash)
  94
  95 (defvar mh-thread-subject-hash nil
  96   "Hashtable used to canonicalize subject strings.")
  97 (make-variable-buffer-local 'mh-thread-subject-hash)
  98
  99 (defvar mh-thread-id-table nil
 100   "Thread ID table maps from message identifiers to message containers.")
 101 (make-variable-buffer-local 'mh-thread-id-table)
 102
 103 (defvar mh-thread-index-id-map nil
 104   "Table to look up message identifier from message index.")
 105 (make-variable-buffer-local 'mh-thread-index-id-map)
 106
 107 (defvar mh-thread-id-index-map nil
 108   "Table to look up message index number from message identifier.")
 109 (make-variable-buffer-local 'mh-thread-id-index-map)
 110
 111 (defvar mh-thread-subject-container-hash nil
 112   "Hashtable used to group messages by subject.")
 113 (make-variable-buffer-local 'mh-thread-subject-container-hash)
 114
 115 (defvar mh-thread-duplicates nil
 116   "Hashtable used to associate messages with the same message identifier.")
 117 (make-variable-buffer-local 'mh-thread-duplicates)
 118
 119 (defvar mh-thread-history ()
 120   "Variable to remember the transformations to the thread tree.
 121 When new messages are added, these transformations are rewound,
 122 then the links are added from the newly seen messages. Finally
 123 the transformations are redone to get the new thread tree. This
 124 makes incremental threading easier.")
 125 (make-variable-buffer-local 'mh-thread-history)
 126
 127 (defvar mh-thread-body-width nil
 128   "Width of scan substring that contains subject and body of message.")
 129
 130 \f
 131
 132 ;;; MH-Folder Commands
 133
 134 ;;;###mh-autoload
 135 (defun mh-thread-ancestor (&optional thread-root-flag)
 136   "Display ancestor of current message.
 137
 138 If you do not care for the way a particular thread has turned,
 139 you can move up the chain of messages with this command. This
 140 command can also take a prefix argument THREAD-ROOT-FLAG to jump
 141 to the message that started everything."
 142   (interactive "P")
 143   (beginning-of-line)
 144   (cond ((not (memq 'unthread mh-view-ops))
 145          (error "Folder isn't threaded"))
 146         ((eobp)
 147          (error "No message at point")))
 148   (let ((current-level (mh-thread-current-indentation-level)))
 149     (cond (thread-root-flag
 150            (while (mh-thread-immediate-ancestor))
 151            (mh-maybe-show))
 152           ((equal current-level 1)
 153            (message "Message has no ancestor"))
 154           (t (mh-thread-immediate-ancestor)
 155              (mh-maybe-show)))))
 156
 157 ;;;###mh-autoload
 158 (defun mh-thread-delete ()
 159   "Delete thread."
 160   (interactive)
 161   (cond ((not (memq 'unthread mh-view-ops))
 162          (error "Folder isn't threaded"))
 163         ((eobp)
 164          (error "No message at point"))
 165         (t (let ((region (mh-thread-find-children)))
 166              (mh-iterate-on-messages-in-region () (car region) (cadr region)
 167                (mh-delete-a-msg nil))
 168              (mh-next-msg)))))
 169
 170 ;;;###mh-autoload
 171 (defun mh-thread-next-sibling (&optional previous-flag)
 172   "Display next sibling.
 173
 174 With non-nil optional argument PREVIOUS-FLAG jump to the previous
 175 sibling."
 176   (interactive)
 177   (cond ((not (memq 'unthread mh-view-ops))
 178          (error "Folder isn't threaded"))
 179         ((eobp)
 180          (error "No message at point")))
 181   (beginning-of-line)
 182   (let ((point (point))
 183         (done nil)
 184         (my-level (mh-thread-current-indentation-level)))
 185     (while (and (not done)
 186                 (equal (forward-line (if previous-flag -1 1)) 0)
 187                 (not (eobp)))
 188       (let ((level (mh-thread-current-indentation-level)))
 189         (cond ((equal level my-level)
 190                (setq done 'success))
 191               ((< level my-level)
 192                (message "No %s sibling" (if previous-flag "previous" "next"))
 193                (setq done 'failure)))))
 194     (cond ((eq done 'success) (mh-maybe-show))
 195           ((eq done 'failure) (goto-char point))
 196           (t (message "No %s sibling" (if previous-flag "previous" "next"))
 197              (goto-char point)))))
 198
 199 ;;;###mh-autoload
 200 (defun mh-thread-previous-sibling ()
 201   "Display previous sibling."
 202   (interactive)
 203   (mh-thread-next-sibling t))
 204
 205 ;;;###mh-autoload
 206 (defun mh-thread-refile (folder)
 207   "Refile (output) thread into FOLDER."
 208   (interactive (list (intern (mh-prompt-for-refile-folder))))
 209   (cond ((not (memq 'unthread mh-view-ops))
 210          (error "Folder isn't threaded"))
 211         ((eobp)
 212          (error "No message at point"))
 213         (t (let ((region (mh-thread-find-children)))
 214              (mh-iterate-on-messages-in-region () (car region) (cadr region)
 215                (mh-refile-a-msg nil folder))
 216              (mh-next-msg)))))
 217
 218 ;;;###mh-autoload
 219 (defun mh-toggle-threads ()
 220   "Toggle threaded view of folder."
 221   (interactive)
 222   (let ((msg-at-point (mh-get-msg-num nil))
 223         (old-buffer-modified-flag (buffer-modified-p))
 224         (buffer-read-only nil))
 225     (cond ((memq 'unthread mh-view-ops)
 226            (unless (mh-valid-view-change-operation-p 'unthread)
 227              (error "Can't unthread folder"))
 228            (let ((msg-list ()))
 229              (goto-char (point-min))
 230              (while (not (eobp))
 231                (let ((index (mh-get-msg-num nil)))
 232                  (when index
 233                    (push index msg-list)))
 234                (forward-line))
 235              (mh-scan-folder mh-current-folder
 236                              (mapcar #'(lambda (x) (format "%s" x))
 237                                      (mh-coalesce-msg-list msg-list))
 238                              t))
 239            (when mh-index-data
 240              (mh-index-insert-folder-headers)
 241              (mh-notate-cur)))
 242           (t (mh-thread-folder)
 243              (push 'unthread mh-view-ops)))
 244     (when msg-at-point (mh-goto-msg msg-at-point t t))
 245     (set-buffer-modified-p old-buffer-modified-flag)
 246     (mh-recenter nil)))
 247
 248 \f
 249
 250 ;;; Support Routines
 251
 252 (defun mh-thread-current-indentation-level ()
 253   "Find the number of spaces by which current message is indented."
 254   (save-excursion
 255     (let ((address-start-offset (+ mh-cmd-note mh-scan-date-flag-width
 256                                    mh-scan-date-width 1))
 257           (level 0))
 258       (beginning-of-line)
 259       (forward-char address-start-offset)
 260       (while (char-equal (char-after) ? )
 261         (incf level)
 262         (forward-char))
 263       level)))
 264
 265 (defun mh-thread-immediate-ancestor ()
 266   "Jump to immediate ancestor in thread tree."
 267   (beginning-of-line)
 268   (let ((point (point))
 269         (ancestor-level (- (mh-thread-current-indentation-level) 2))
 270         (done nil))
 271     (if (< ancestor-level 0)
 272         nil
 273       (while (and (not done) (equal (forward-line -1) 0))
 274         (when (equal ancestor-level (mh-thread-current-indentation-level))
 275           (setq done t)))
 276       (unless done
 277         (goto-char point))
 278       done)))
 279
 280 (defun mh-thread-find-children ()
 281   "Return a region containing the current message and its children.
 282 The result is returned as a list of two elements. The first is
 283 the point at the start of the region and the second is the point
 284 at the end."
 285   (beginning-of-line)
 286   (if (eobp)
 287       nil
 288     (let ((address-start-offset (+ mh-cmd-note mh-scan-date-flag-width
 289                                    mh-scan-date-width 1))
 290           (level (mh-thread-current-indentation-level))
 291           spaces begin)
 292       (setq begin (point))
 293       (setq spaces (format (format "%%%ss" (1+ level)) ""))
 294       (forward-line)
 295       (block nil
 296         (while (not (eobp))
 297           (forward-char address-start-offset)
 298           (unless (equal (string-match spaces (buffer-substring-no-properties
 299                                                (point) (mh-line-end-position)))
 300                          0)
 301             (beginning-of-line)
 302             (backward-char)
 303             (return))
 304           (forward-line)))
 305       (list begin (point)))))
 306
 307 \f
 308
 309 ;;; Thread Creation
 310
 311 (defun mh-thread-folder ()
 312   "Generate thread view of folder."
 313   (message "Threading %s..." (buffer-name))
 314   (mh-thread-initialize)
 315   (goto-char (point-min))
 316   (mh-remove-all-notation)
 317   (let ((msg-list ()))
 318     (mh-iterate-on-range msg (cons (point-min) (point-max))
 319       (setf (gethash msg mh-thread-scan-line-map) (mh-thread-parse-scan-line))
 320       (push msg msg-list))
 321     (let* ((range (mh-coalesce-msg-list msg-list))
 322            (thread-tree (mh-thread-generate (buffer-name) range)))
 323       (delete-region (point-min) (point-max))
 324       (mh-thread-print-scan-lines thread-tree)
 325       (mh-notate-user-sequences)
 326       (mh-notate-deleted-and-refiled)
 327       (mh-notate-cur)
 328       (message "Threading %s...done" (buffer-name)))))
 329
 330 ;;;###mh-autoload
 331 (defun mh-thread-inc (folder start-point)
 332   "Update thread tree for FOLDER.
 333 All messages after START-POINT are added to the thread tree."
 334   (mh-thread-rewind-pruning)
 335   (mh-remove-all-notation)
 336   (goto-char start-point)
 337   (let ((msg-list ()))
 338     (while (not (eobp))
 339       (let ((index (mh-get-msg-num nil)))
 340         (when (numberp index)
 341           (push index msg-list)
 342           (setf (gethash index mh-thread-scan-line-map)
 343                 (mh-thread-parse-scan-line)))
 344         (forward-line)))
 345     (let ((thread-tree (mh-thread-generate folder msg-list))
 346           (buffer-read-only nil)
 347           (old-buffer-modified-flag (buffer-modified-p)))
 348       (delete-region (point-min) (point-max))
 349       (mh-thread-print-scan-lines thread-tree)
 350       (mh-notate-user-sequences)
 351       (mh-notate-deleted-and-refiled)
 352       (mh-notate-cur)
 353       (set-buffer-modified-p old-buffer-modified-flag))))
 354
 355 (defmacro mh-thread-initialize-hash (var test)
 356   "Initialize the hash table in VAR.
 357 TEST is the test to use when creating a new hash table."
 358   (unless (symbolp var) (error "Expected a symbol: %s" var))
 359   `(if ,var (clrhash ,var) (setq ,var (make-hash-table :test ,test))))
 360
 361 (defun mh-thread-initialize ()
 362   "Make new hash tables, or clear them if already present."
 363   (mh-thread-initialize-hash mh-thread-id-hash #'equal)
 364   (mh-thread-initialize-hash mh-thread-subject-hash #'equal)
 365   (mh-thread-initialize-hash mh-thread-id-table #'eq)
 366   (mh-thread-initialize-hash mh-thread-id-index-map #'eq)
 367   (mh-thread-initialize-hash mh-thread-index-id-map #'eql)
 368   (mh-thread-initialize-hash mh-thread-scan-line-map #'eql)
 369   (mh-thread-initialize-hash mh-thread-subject-container-hash #'eq)
 370   (mh-thread-initialize-hash mh-thread-duplicates #'eq)
 371   (setq mh-thread-history ()))
 372
 373 (defsubst mh-thread-id-container (id)
 374   "Given ID, return the corresponding container in `mh-thread-id-table'.
 375 If no container exists then a suitable container is created and
 376 the id-table is updated."
 377   (when (not id)
 378     (error "1"))
 379   (or (gethash id mh-thread-id-table)
 380       (setf (gethash id mh-thread-id-table)
 381             (let ((message (mh-thread-make-message :id id)))
 382               (mh-thread-make-container :message message)))))
 383
 384 (defsubst mh-thread-remove-parent-link (child)
 385   "Remove parent link of CHILD if it exists."
 386   (let* ((child-container (if (mh-thread-container-p child)
 387                               child (mh-thread-id-container child)))
 388          (parent-container (mh-container-parent child-container)))
 389     (when parent-container
 390       (setf (mh-container-children parent-container)
 391             (loop for elem in (mh-container-children parent-container)
 392                   unless (eq child-container elem) collect elem))
 393       (setf (mh-container-parent child-container) nil))))
 394
 395 (defsubst mh-thread-add-link (parent child &optional at-end-p)
 396   "Add links so that PARENT becomes a parent of CHILD.
 397 Doesn't make any changes if CHILD is already an ancestor of
 398 PARENT. If optional argument AT-END-P is non-nil, the CHILD is
 399 added to the end of the children list of PARENT."
 400   (let ((parent-container (cond ((null parent) nil)
 401                                 ((mh-thread-container-p parent) parent)
 402                                 (t (mh-thread-id-container parent))))
 403         (child-container (if (mh-thread-container-p child)
 404                              child (mh-thread-id-container child))))
 405     (when (and parent-container
 406                (not (mh-thread-ancestor-p child-container parent-container))
 407                (not (mh-thread-ancestor-p parent-container child-container)))
 408       (mh-thread-remove-parent-link child-container)
 409       (cond ((not at-end-p)
 410              (push child-container (mh-container-children parent-container)))
 411             ((null (mh-container-children parent-container))
 412              (push child-container (mh-container-children parent-container)))
 413             (t (let ((last-child (mh-container-children parent-container)))
 414                  (while (cdr last-child)
 415                    (setq last-child (cdr last-child)))
 416                  (setcdr last-child (cons child-container nil)))))
 417       (setf (mh-container-parent child-container) parent-container))
 418     (unless parent-container
 419       (mh-thread-remove-parent-link child-container))))
 420
 421 (defun mh-thread-rewind-pruning ()
 422   "Restore the thread tree to its state before pruning."
 423   (while mh-thread-history
 424     (let ((action (pop mh-thread-history)))
 425       (cond ((eq (car action) 'DROP)
 426              (mh-thread-remove-parent-link (cadr action))
 427              (mh-thread-add-link (caddr action) (cadr action)))
 428             ((eq (car action) 'PROMOTE)
 429              (let ((node (cadr action))
 430                    (parent (caddr action))
 431                    (children (cdddr action)))
 432                (dolist (child children)
 433                  (mh-thread-remove-parent-link child)
 434                  (mh-thread-add-link node child))
 435                (mh-thread-add-link parent node)))
 436             ((eq (car action) 'SUBJECT)
 437              (let ((node (cadr action)))
 438                (mh-thread-remove-parent-link node)
 439                (setf (mh-container-real-child-p node) t)))))))
 440
 441 (defun mh-thread-ancestor-p (ancestor successor)
 442   "Return t if ANCESTOR is really an ancestor of SUCCESSOR and nil otherwise.
 443 In the limit, the function returns t if ANCESTOR and SUCCESSOR
 444 are the same containers."
 445   (block nil
 446     (while successor
 447       (when (eq ancestor successor) (return t))
 448       (setq successor (mh-container-parent successor)))
 449     nil))
 450
 451 ;; Another and may be better approach would be to generate all the info from
 452 ;; the scan which generates the threading info. For now this will have to do.
 453 ;;;###mh-autoload
 454 (defun mh-thread-parse-scan-line (&optional string)
 455   "Parse a scan line.
 456 If optional argument STRING is given then that is assumed to be
 457 the scan line. Otherwise uses the line at point as the scan line
 458 to parse."
 459   (let* ((string (or string (buffer-substring-no-properties
 460                              (mh-line-beginning-position)
 461                              (mh-line-end-position))))
 462          (address-start (+ mh-cmd-note mh-scan-field-from-start-offset))
 463          (body-start (+ mh-cmd-note mh-scan-field-from-end-offset))
 464          (first-string (substring string 0 address-start)))
 465     (list first-string
 466           (substring string address-start (- body-start 2))
 467           (substring string body-start)
 468           string)))
 469
 470 (defsubst mh-thread-canonicalize-id (id)
 471   "Produce canonical string representation for ID.
 472 This allows cheap string comparison with EQ."
 473   (or (and (equal id "") (copy-sequence ""))
 474       (gethash id mh-thread-id-hash)
 475       (setf (gethash id mh-thread-id-hash) id)))
 476
 477 (defsubst mh-thread-prune-subject (subject)
 478   "Prune leading Re:'s, Fwd:'s etc. and trailing (fwd)'s from SUBJECT.
 479 If the result after pruning is not the empty string then it is
 480 canonicalized so that subjects can be tested for equality with
 481 eq. This is done so that all the messages without a subject are
 482 not put into a single thread."
 483   (let ((case-fold-search t)
 484         (subject-pruned-flag nil))
 485     ;; Prune subject leader
 486     (while (or (string-match "^[ \t]*\\(re\\|fwd?\\)\\(\\[[0-9]*\\]\\)?:[ \t]*"
 487                              subject)
 488                (string-match "^[ \t]*\\[[^\\]][ \t]*" subject))
 489       (setq subject-pruned-flag t)
 490       (setq subject (substring subject (match-end 0))))
 491     ;; Prune subject trailer
 492     (while (or (string-match "(fwd)$" subject)
 493                (string-match "[ \t]+$" subject))
 494       (setq subject-pruned-flag t)
 495       (setq subject (substring subject 0 (match-beginning 0))))
 496     ;; Canonicalize subject only if it is non-empty
 497     (cond ((equal subject "") (list subject subject-pruned-flag))
 498           (t (list
 499               (or (gethash subject mh-thread-subject-hash)
 500                   (setf (gethash subject mh-thread-subject-hash) subject))
 501               subject-pruned-flag)))))
 502
 503 (defsubst mh-thread-group-by-subject (roots)
 504   "Group the set of message containers, ROOTS based on subject.
 505 Bug: Check for and make sure that something without Re: is made
 506 the parent in preference to something that has it."
 507   (clrhash mh-thread-subject-container-hash)
 508   (let ((results ()))
 509     (dolist (root roots)
 510       (let* ((subject (mh-thread-container-subject root))
 511              (parent (gethash subject mh-thread-subject-container-hash)))
 512         (cond (parent (mh-thread-remove-parent-link root)
 513                       (mh-thread-add-link parent root t)
 514                       (setf (mh-container-real-child-p root) nil)
 515                       (push `(SUBJECT ,root) mh-thread-history))
 516               (t
 517                (setf (gethash subject mh-thread-subject-container-hash) root)
 518                (push root results)))))
 519     (nreverse results)))
 520
 521 (defun mh-thread-container-subject (container)
 522   "Return the subject of CONTAINER.
 523 If CONTAINER is empty return the subject info of one of its
 524 children."
 525   (cond ((and (mh-container-message container)
 526               (mh-message-id (mh-container-message container)))
 527          (mh-message-subject (mh-container-message container)))
 528         (t (block nil
 529              (dolist (kid (mh-container-children container))
 530                (when (and (mh-container-message kid)
 531                           (mh-message-id (mh-container-message kid)))
 532                  (let ((kid-message (mh-container-message kid)))
 533                    (return (mh-message-subject kid-message)))))
 534              (error "This can't happen")))))
 535
 536 (defsubst mh-thread-update-id-index-maps (id index)
 537   "Message with id, ID is the message in INDEX.
 538 The function also checks for duplicate messages (that is multiple
 539 messages with the same ID). These messages are put in the
 540 `mh-thread-duplicates' hash table."
 541   (let ((old-index (gethash id mh-thread-id-index-map)))
 542     (when old-index (push old-index (gethash id mh-thread-duplicates)))
 543     (setf (gethash id mh-thread-id-index-map) index)
 544     (setf (gethash index mh-thread-index-id-map) id)))
 545
 546 (defsubst mh-thread-get-message-container (message)
 547   "Return container which has MESSAGE in it.
 548 If there is no container present then a new container is
 549 allocated."
 550   (let* ((id (mh-message-id message))
 551          (container (gethash id mh-thread-id-table)))
 552     (cond (container (setf (mh-container-message container) message)
 553                      container)
 554           (t (setf (gethash id mh-thread-id-table)
 555                    (mh-thread-make-container :message message))))))
 556
 557 (defsubst mh-thread-get-message (id subject-re-p subject refs)
 558   "Return appropriate message.
 559 Otherwise update message already present to have the proper ID,
 560 SUBJECT-RE-P, SUBJECT and REFS fields."
 561   (let* ((container (gethash id mh-thread-id-table))
 562          (message (if container (mh-container-message container) nil)))
 563     (cond (message
 564            (setf (mh-message-subject-re-p message) subject-re-p)
 565            (setf (mh-message-subject message) subject)
 566            (setf (mh-message-id message) id)
 567            (setf (mh-message-references message) refs)
 568            message)
 569           (container
 570            (setf (mh-container-message container)
 571                  (mh-thread-make-message :id id :references refs
 572                                          :subject subject
 573                                          :subject-re-p subject-re-p)))
 574           (t (let ((message (mh-thread-make-message :id id :references refs
 575                                                     :subject-re-p subject-re-p
 576                                                     :subject subject)))
 577                (prog1 message
 578                  (mh-thread-get-message-container message)))))))
 579
 580 (defvar mh-message-id-regexp "^<.*@.*>$"
 581   "Regexp to recognize whether a string is a message identifier.")
 582
 583 ;;;###mh-autoload
 584 (defun mh-thread-generate (folder msg-list)
 585   "Scan FOLDER to get info for threading.
 586 Only information about messages in MSG-LIST are added to the tree."
 587   (with-temp-buffer
 588     (mh-thread-set-tables folder)
 589     (when msg-list
 590       (apply
 591        #'call-process (expand-file-name mh-scan-prog mh-progs) nil '(t nil) nil
 592        "-width" "10000" "-format"
 593        "%(msg)\n%{message-id}\n%{references}\n%{in-reply-to}\n%{subject}\n"
 594        folder (mapcar #'(lambda (x) (format "%s" x)) msg-list)))
 595     (goto-char (point-min))
 596     (let ((roots ())
 597           (case-fold-search t))
 598       (block nil
 599         (while (not (eobp))
 600           (block process-message
 601             (let* ((index-line
 602                     (prog1 (buffer-substring (point) (mh-line-end-position))
 603                       (forward-line)))
 604                    (index (string-to-number index-line))
 605                    (id (prog1 (buffer-substring (point) (mh-line-end-position))
 606                          (forward-line)))
 607                    (refs (prog1
 608                              (buffer-substring (point) (mh-line-end-position))
 609                            (forward-line)))
 610                    (in-reply-to (prog1 (buffer-substring (point)
 611                                                          (mh-line-end-position))
 612                                   (forward-line)))
 613                    (subject (prog1
 614                                 (buffer-substring
 615                                  (point) (mh-line-end-position))
 616                               (forward-line)))
 617                    (subject-re-p nil))
 618               (unless (gethash index mh-thread-scan-line-map)
 619                 (return-from process-message))
 620               (unless (integerp index) (return)) ;Error message here
 621               (multiple-value-setq (subject subject-re-p)
 622                 (values-list (mh-thread-prune-subject subject)))
 623               (setq in-reply-to (mh-thread-process-in-reply-to in-reply-to))
 624               (setq refs (loop for x in (append (split-string refs) in-reply-to)
 625                                when (string-match mh-message-id-regexp x)
 626                                collect x))
 627               (setq id (mh-thread-canonicalize-id id))
 628               (mh-thread-update-id-index-maps id index)
 629               (setq refs (mapcar #'mh-thread-canonicalize-id refs))
 630               (mh-thread-get-message id subject-re-p subject refs)
 631               (do ((ancestors refs (cdr ancestors)))
 632                   ((null (cdr ancestors))
 633                    (when (car ancestors)
 634                      (mh-thread-remove-parent-link id)
 635                      (mh-thread-add-link (car ancestors) id)))
 636                 (mh-thread-add-link (car ancestors) (cadr ancestors)))))))
 637       (maphash #'(lambda (k v)
 638                    (declare (ignore k))
 639                    (when (null (mh-container-parent v))
 640                      (push v roots)))
 641                mh-thread-id-table)
 642       (setq roots (mh-thread-prune-containers roots))
 643       (prog1 (setq roots (mh-thread-group-by-subject roots))
 644         (let ((history mh-thread-history))
 645           (set-buffer folder)
 646           (setq mh-thread-history history))))))
 647
 648 (defun mh-thread-set-tables (folder)
 649   "Use the tables of FOLDER in current buffer."
 650   (mh-cl-flet
 651    ((mh-get-table (symbol)
 652                   (with-current-buffer folder
 653                     (symbol-value symbol))))
 654    (setq mh-thread-id-hash (mh-get-table 'mh-thread-id-hash))
 655    (setq mh-thread-subject-hash (mh-get-table 'mh-thread-subject-hash))
 656    (setq mh-thread-id-table (mh-get-table 'mh-thread-id-table))
 657    (setq mh-thread-id-index-map (mh-get-table 'mh-thread-id-index-map))
 658    (setq mh-thread-index-id-map (mh-get-table 'mh-thread-index-id-map))
 659    (setq mh-thread-scan-line-map (mh-get-table 'mh-thread-scan-line-map))
 660    (setq mh-thread-subject-container-hash
 661          (mh-get-table 'mh-thread-subject-container-hash))
 662    (setq mh-thread-duplicates (mh-get-table 'mh-thread-duplicates))
 663    (setq mh-thread-history (mh-get-table 'mh-thread-history))))
 664
 665 (defun mh-thread-process-in-reply-to (reply-to-header)
 666   "Extract message id's from REPLY-TO-HEADER.
 667 Ideally this should have some regexp which will try to guess if a
 668 string between < and > is a message id and not an email address.
 669 For now it will take the last string inside angles."
 670   (let ((end (mh-search-from-end ?> reply-to-header)))
 671     (when (numberp end)
 672       (let ((begin (mh-search-from-end ?< (substring reply-to-header 0 end))))
 673         (when (numberp begin)
 674           (list (substring reply-to-header begin (1+ end))))))))
 675
 676 (defun mh-thread-prune-containers (roots)
 677   "Prune empty containers in the containers ROOTS."
 678   (let ((dfs-ordered-nodes ())
 679         (work-list roots))
 680     (while work-list
 681       (let ((node (pop work-list)))
 682         (dolist (child (mh-container-children node))
 683           (push child work-list))
 684         (push node dfs-ordered-nodes)))
 685     (while dfs-ordered-nodes
 686       (let ((node (pop dfs-ordered-nodes)))
 687         (cond ((gethash (mh-message-id (mh-container-message node))
 688                         mh-thread-id-index-map)
 689                ;; Keep it
 690                (setf (mh-container-children node)
 691                      (mh-thread-sort-containers (mh-container-children node))))
 692               ((and (mh-container-children node)
 693                     (or (null (cdr (mh-container-children node)))
 694                         (mh-container-parent node)))
 695                ;; Promote kids
 696                (let ((children ()))
 697                  (dolist (kid (mh-container-children node))
 698                    (mh-thread-remove-parent-link kid)
 699                    (mh-thread-add-link (mh-container-parent node) kid)
 700                    (push kid children))
 701                  (push `(PROMOTE ,node ,(mh-container-parent node) ,@children)
 702                        mh-thread-history)
 703                  (mh-thread-remove-parent-link node)))
 704               ((mh-container-children node)
 705                ;; Promote the first orphan to parent and add the other kids as
 706                ;; his children
 707                (setf (mh-container-children node)
 708                      (mh-thread-sort-containers (mh-container-children node)))
 709                (let ((new-parent (car (mh-container-children node)))
 710                      (other-kids (cdr (mh-container-children node))))
 711                  (mh-thread-remove-parent-link new-parent)
 712                  (dolist (kid other-kids)
 713                    (mh-thread-remove-parent-link kid)
 714                    (setf (mh-container-real-child-p kid) nil)
 715                    (mh-thread-add-link new-parent kid t))
 716                  (push `(PROMOTE ,node ,(mh-container-parent node)
 717                                  ,new-parent ,@other-kids)
 718                        mh-thread-history)
 719                  (mh-thread-remove-parent-link node)))
 720               (t
 721                ;; Drop it
 722                (push `(DROP ,node ,(mh-container-parent node))
 723                      mh-thread-history)
 724                (mh-thread-remove-parent-link node)))))
 725     (let ((results ()))
 726       (maphash #'(lambda (k v)
 727                    (declare (ignore k))
 728                    (when (and (null (mh-container-parent v))
 729                               (gethash (mh-message-id (mh-container-message v))
 730                                        mh-thread-id-index-map))
 731                      (push v results)))
 732                mh-thread-id-table)
 733       (mh-thread-sort-containers results))))
 734
 735 (defun mh-thread-sort-containers (containers)
 736   "Sort a list of message CONTAINERS to be in ascending order wrt index."
 737   (sort containers
 738         #'(lambda (x y)
 739             (when (and (mh-container-message x) (mh-container-message y))
 740               (let* ((id-x (mh-message-id (mh-container-message x)))
 741                      (id-y (mh-message-id (mh-container-message y)))
 742                      (index-x (gethash id-x mh-thread-id-index-map))
 743                      (index-y (gethash id-y mh-thread-id-index-map)))
 744                 (and (integerp index-x) (integerp index-y)
 745                      (< index-x index-y)))))))
 746
 747 (defvar mh-thread-last-ancestor)
 748
 749 ;;;###mh-autoload
 750 (defun mh-thread-print-scan-lines (thread-tree)
 751   "Print scan lines in THREAD-TREE in threaded mode."
 752   (let ((mh-thread-body-width (- (window-width) mh-cmd-note
 753                                  (1- mh-scan-field-subject-start-offset)))
 754         (mh-thread-last-ancestor nil))
 755     (if (null mh-index-data)
 756         (mh-thread-generate-scan-lines thread-tree -2)
 757       (loop for x in (mh-index-group-by-folder)
 758             do (let* ((old-map mh-thread-scan-line-map)
 759                       (mh-thread-scan-line-map (make-hash-table)))
 760                  (setq mh-thread-last-ancestor nil)
 761                  (loop for msg in (cdr x)
 762                        do (let ((v (gethash msg old-map)))
 763                             (when v
 764                               (setf (gethash msg mh-thread-scan-line-map) v))))
 765                  (when (> (hash-table-count mh-thread-scan-line-map) 0)
 766                    (insert (if (bobp) "" "\n") (car x) "\n")
 767                    (mh-thread-generate-scan-lines thread-tree -2))))
 768       (mh-index-create-imenu-index))))
 769
 770 (defun mh-thread-generate-scan-lines (tree level)
 771   "Generate scan lines.
 772 TREE is the hierarchical tree of messages, SCAN-LINE-MAP maps
 773 message indices to the corresponding scan lines and LEVEL used to
 774 determine indentation of the message."
 775   (cond ((null tree) nil)
 776         ((mh-thread-container-p tree)
 777          (let* ((message (mh-container-message tree))
 778                 (id (mh-message-id message))
 779                 (index (gethash id mh-thread-id-index-map))
 780                 (duplicates (gethash id mh-thread-duplicates))
 781                 (new-level (+ level 2))
 782                 (dupl-flag t)
 783                 (force-angle-flag nil)
 784                 (increment-level-flag nil))
 785            (dolist (scan-line (mapcar (lambda (x)
 786                                         (gethash x mh-thread-scan-line-map))
 787                                       (reverse (cons index duplicates))))
 788              (when scan-line
 789                (when (and dupl-flag (equal level 0)
 790                           (mh-thread-ancestor-p mh-thread-last-ancestor tree))
 791                  (setq level (+ level 2)
 792                        new-level (+ new-level 2)
 793                        force-angle-flag t))
 794                (when (equal level 0)
 795                  (setq mh-thread-last-ancestor tree)
 796                  (while (mh-container-parent mh-thread-last-ancestor)
 797                    (setq mh-thread-last-ancestor
 798                          (mh-container-parent mh-thread-last-ancestor))))
 799                (let* ((lev (if dupl-flag level new-level))
 800                       (square-flag (or (and (mh-container-real-child-p tree)
 801                                             (not force-angle-flag)
 802                                             dupl-flag)
 803                                        (equal lev 0))))
 804                  (insert (car scan-line)
 805                          (format (format "%%%ss" lev) "")
 806                          (if square-flag "[" "<")
 807                          (cadr scan-line)
 808                          (if square-flag "]" ">")
 809                          (truncate-string-to-width
 810                           (caddr scan-line) (- mh-thread-body-width lev))
 811                          "\n"))
 812                (setq increment-level-flag t)
 813                (setq dupl-flag nil)))
 814            (unless increment-level-flag (setq new-level level))
 815            (dolist (child (mh-container-children tree))
 816              (mh-thread-generate-scan-lines child new-level))))
 817         (t (let ((nlevel (+ level 2)))
 818              (dolist (ch tree)
 819                (mh-thread-generate-scan-lines ch nlevel))))))
 820
 821 \f
 822
 823 ;;; Additional Utilities
 824
 825 ;;;###mh-autoload
 826 (defun mh-thread-update-scan-line-map (msg notation offset)
 827   "In threaded view update `mh-thread-scan-line-map'.
 828 MSG is the message being notated with NOTATION at OFFSET."
 829   (let* ((msg (or msg (mh-get-msg-num nil)))
 830          (cur-scan-line (and mh-thread-scan-line-map
 831                              (gethash msg mh-thread-scan-line-map)))
 832          (old-scan-lines (loop for map in mh-thread-scan-line-map-stack
 833                                collect (and map (gethash msg map)))))
 834     (when cur-scan-line
 835       (setf (aref (car cur-scan-line) offset) notation))
 836     (dolist (line old-scan-lines)
 837       (when line (setf (aref (car line) offset) notation)))))
 838
 839 ;;;###mh-autoload
 840 (defun mh-thread-find-msg-subject (msg)
 841   "Find canonicalized subject of MSG.
 842 This function can only be used the folder is threaded."
 843   (ignore-errors
 844     (mh-message-subject
 845      (mh-container-message (gethash (gethash msg mh-thread-index-id-map)
 846                                     mh-thread-id-table)))))
 847
 848 ;;;###mh-autoload
 849 (defun mh-thread-add-spaces (count)
 850   "Add COUNT spaces to each scan line in `mh-thread-scan-line-map'."
 851   (let ((spaces (format (format "%%%ss" count) "")))
 852     (while (not (eobp))
 853       (let* ((msg-num (mh-get-msg-num nil))
 854              (old-line (nth 3 (gethash msg-num mh-thread-scan-line-map))))
 855         (when (numberp msg-num)
 856           (setf (gethash msg-num mh-thread-scan-line-map)
 857                 (mh-thread-parse-scan-line (format "%s%s" spaces old-line)))))
 858       (forward-line 1))))
 859
 860 ;;;###mh-autoload
 861 (defun mh-thread-forget-message (index)
 862   "Forget the message INDEX from the threading tables."
 863   (let* ((id (gethash index mh-thread-index-id-map))
 864          (id-index (gethash id mh-thread-id-index-map))
 865          (duplicates (gethash id mh-thread-duplicates)))
 866     (remhash index mh-thread-index-id-map)
 867     (remhash index mh-thread-scan-line-map)
 868     (cond ((and (eql index id-index) (null duplicates))
 869            (remhash id mh-thread-id-index-map))
 870           ((eql index id-index)
 871            (setf (gethash id mh-thread-id-index-map) (car duplicates))
 872            (setf (gethash (car duplicates) mh-thread-index-id-map) id)
 873            (setf (gethash id mh-thread-duplicates) (cdr duplicates)))
 874           (t
 875            (setf (gethash id mh-thread-duplicates)
 876                  (remove index duplicates))))))
 877
 878 (provide 'mh-thread)
 879
 880 ;; Local Variables:
 881 ;; indent-tabs-mode: nil
 882 ;; sentence-end-double-space: nil
 883 ;; End:
 884
 885 ;;; mh-thread.el ends here