lisp/mh-e/mh-thread.el

   1 ;;; mh-thread.el --- MH-E threading support
   2
   3 ;; Copyright (C) 2002, 2003, 2004, 2006, 2007, 2008, 2009, 2010, 2011
   4 ;;   Free Software Foundation, Inc.
   5
   6 ;; Author: Satyaki Das <satyaki@theforce.stanford.edu>
   7 ;; Maintainer: Bill Wohler <wohler@newt.com>
   8 ;; Keywords: mail
   9 ;; See: mh-e.el
  10
  11 ;; This file is part of GNU Emacs.
  12
  13 ;; GNU Emacs is free software: you can redistribute it and/or modify
  14 ;; it under the terms of the GNU General Public License as published by
  15 ;; the Free Software Foundation, either version 3 of the License, or
  16 ;; (at your option) any later version.
  17
  18 ;; GNU Emacs is distributed in the hope that it will be useful,
  19 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 ;; GNU General Public License for more details.
  22
  23 ;; You should have received a copy of the GNU General Public License
  24 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  25
  26 ;;; Commentary:
  27
  28 ;; The threading portion of this files tries to implement the
  29 ;; algorithm described at:
  30 ;;   http://www.jwz.org/doc/threading.html
  31 ;; It also begins to implement the IMAP Threading extension RFC. The
  32 ;; implementation lacks the reference and subject canonicalization of
  33 ;; the RFC.
  34
  35 ;; In the presentation buffer, children messages are shown indented
  36 ;; with either [ ] or < > around them. Square brackets ([ ]) denote
  37 ;; that the algorithm can point out some headers which when taken
  38 ;; together implies that the unindented message is an ancestor of the
  39 ;; indented message. If no such proof exists then angles (< >) are
  40 ;; used.
  41
  42 ;; If threading is slow on your machine, compile this file. Of all the
  43 ;; files in MH-E, this one really benefits from compilation.
  44
  45 ;; Some issues and problems are as follows:
  46
  47 ;;  (1) Scan truncates the fields at length 512. So longer
  48 ;;      references: headers get mutilated. The same kind of MH
  49 ;;      format string works when composing messages. Is there a way
  50 ;;      to avoid this? My scan command is as follows:
  51 ;;        scan +folder -width 10000 \
  52 ;;             -format "%(msg)\n%{message-id}\n%{references}\n%{subject}\n"
  53 ;;      I would really appreciate it if someone would help me with this.
  54
  55 ;;  (2) Implement heuristics to recognize message identifiers in
  56 ;;      In-Reply-To: header. Right now it just assumes that the last
  57 ;;      text between angles (< and >) is the message identifier.
  58 ;;      There is the chance that this will incorrectly use an email
  59 ;;      address like a message identifier.
  60
  61 ;;  (3) Error checking of found message identifiers should be done.
  62
  63 ;;  (4) Since this breaks the assumption that message indices
  64 ;;      increase as one goes down the buffer, the binary search
  65 ;;      based mh-goto-msg doesn't work. I have a simpler replacement
  66 ;;      which may be less efficient.
  67
  68 ;;  (5) Better canonicalizing for message identifier and subject
  69 ;;      strings.
  70
  71 ;;; Change Log:
  72
  73 ;;; Code:
  74
  75 (require 'mh-e)
  76 (require 'mh-scan)
  77
  78 (mh-defstruct (mh-thread-message (:conc-name mh-message-)
  79                                  (:constructor mh-thread-make-message))
  80   (id nil)
  81   (references ())
  82   (subject "")
  83   (subject-re-p nil))
  84
  85 (mh-defstruct (mh-thread-container (:conc-name mh-container-)
  86                                    (:constructor mh-thread-make-container))
  87   message parent children
  88   (real-child-p t))
  89
  90 (defvar mh-thread-id-hash nil
  91   "Hashtable used to canonicalize message identifiers.")
  92 (make-variable-buffer-local 'mh-thread-id-hash)
  93
  94 (defvar mh-thread-subject-hash nil
  95   "Hashtable used to canonicalize subject strings.")
  96 (make-variable-buffer-local 'mh-thread-subject-hash)
  97
  98 (defvar mh-thread-id-table nil
  99   "Thread ID table maps from message identifiers to message containers.")
 100 (make-variable-buffer-local 'mh-thread-id-table)
 101
 102 (defvar mh-thread-index-id-map nil
 103   "Table to look up message identifier from message index.")
 104 (make-variable-buffer-local 'mh-thread-index-id-map)
 105
 106 (defvar mh-thread-id-index-map nil
 107   "Table to look up message index number from message identifier.")
 108 (make-variable-buffer-local 'mh-thread-id-index-map)
 109
 110 (defvar mh-thread-subject-container-hash nil
 111   "Hashtable used to group messages by subject.")
 112 (make-variable-buffer-local 'mh-thread-subject-container-hash)
 113
 114 (defvar mh-thread-duplicates nil
 115   "Hashtable used to associate messages with the same message identifier.")
 116 (make-variable-buffer-local 'mh-thread-duplicates)
 117
 118 (defvar mh-thread-history ()
 119   "Variable to remember the transformations to the thread tree.
 120 When new messages are added, these transformations are rewound,
 121 then the links are added from the newly seen messages. Finally
 122 the transformations are redone to get the new thread tree. This
 123 makes incremental threading easier.")
 124 (make-variable-buffer-local 'mh-thread-history)
 125
 126 (defvar mh-thread-body-width nil
 127   "Width of scan substring that contains subject and body of message.")
 128
 129 \f
 130
 131 ;;; MH-Folder Commands
 132
 133 ;;;###mh-autoload
 134 (defun mh-thread-ancestor (&optional thread-root-flag)
 135   "Display ancestor of current message.
 136
 137 If you do not care for the way a particular thread has turned,
 138 you can move up the chain of messages with this command. This
 139 command can also take a prefix argument THREAD-ROOT-FLAG to jump
 140 to the message that started everything."
 141   (interactive "P")
 142   (beginning-of-line)
 143   (cond ((not (memq 'unthread mh-view-ops))
 144          (error "Folder isn't threaded"))
 145         ((eobp)
 146          (error "No message at point")))
 147   (let ((current-level (mh-thread-current-indentation-level)))
 148     (cond (thread-root-flag
 149            (while (mh-thread-immediate-ancestor))
 150            (mh-maybe-show))
 151           ((equal current-level 1)
 152            (message "Message has no ancestor"))
 153           (t (mh-thread-immediate-ancestor)
 154              (mh-maybe-show)))))
 155
 156 ;;;###mh-autoload
 157 (defun mh-thread-delete ()
 158   "Delete thread."
 159   (interactive)
 160   (cond ((not (memq 'unthread mh-view-ops))
 161          (error "Folder isn't threaded"))
 162         ((eobp)
 163          (error "No message at point"))
 164         (t (let ((region (mh-thread-find-children)))
 165              (mh-iterate-on-messages-in-region () (car region) (cadr region)
 166                (mh-delete-a-msg nil))
 167              (mh-next-msg)))))
 168
 169 ;;;###mh-autoload
 170 (defun mh-thread-next-sibling (&optional previous-flag)
 171   "Display next sibling.
 172
 173 With non-nil optional argument PREVIOUS-FLAG jump to the previous
 174 sibling."
 175   (interactive)
 176   (cond ((not (memq 'unthread mh-view-ops))
 177          (error "Folder isn't threaded"))
 178         ((eobp)
 179          (error "No message at point")))
 180   (beginning-of-line)
 181   (let ((point (point))
 182         (done nil)
 183         (my-level (mh-thread-current-indentation-level)))
 184     (while (and (not done)
 185                 (equal (forward-line (if previous-flag -1 1)) 0)
 186                 (not (eobp)))
 187       (let ((level (mh-thread-current-indentation-level)))
 188         (cond ((equal level my-level)
 189                (setq done 'success))
 190               ((< level my-level)
 191                (message "No %s sibling" (if previous-flag "previous" "next"))
 192                (setq done 'failure)))))
 193     (cond ((eq done 'success) (mh-maybe-show))
 194           ((eq done 'failure) (goto-char point))
 195           (t (message "No %s sibling" (if previous-flag "previous" "next"))
 196              (goto-char point)))))
 197
 198 ;;;###mh-autoload
 199 (defun mh-thread-previous-sibling ()
 200   "Display previous sibling."
 201   (interactive)
 202   (mh-thread-next-sibling t))
 203
 204 ;;;###mh-autoload
 205 (defun mh-thread-refile (folder)
 206   "Refile (output) thread into FOLDER."
 207   (interactive (list (intern (mh-prompt-for-refile-folder))))
 208   (cond ((not (memq 'unthread mh-view-ops))
 209          (error "Folder isn't threaded"))
 210         ((eobp)
 211          (error "No message at point"))
 212         (t (let ((region (mh-thread-find-children)))
 213              (mh-iterate-on-messages-in-region () (car region) (cadr region)
 214                (mh-refile-a-msg nil folder))
 215              (mh-next-msg)))))
 216
 217 ;;;###mh-autoload
 218 (defun mh-toggle-threads ()
 219   "Toggle threaded view of folder."
 220   (interactive)
 221   (let ((msg-at-point (mh-get-msg-num nil))
 222         (old-buffer-modified-flag (buffer-modified-p))
 223         (buffer-read-only nil))
 224     (cond ((memq 'unthread mh-view-ops)
 225            (unless (mh-valid-view-change-operation-p 'unthread)
 226              (error "Can't unthread folder"))
 227            (let ((msg-list ()))
 228              (goto-char (point-min))
 229              (while (not (eobp))
 230                (let ((index (mh-get-msg-num nil)))
 231                  (when index
 232                    (push index msg-list)))
 233                (forward-line))
 234              (mh-scan-folder mh-current-folder
 235                              (mapcar #'(lambda (x) (format "%s" x))
 236                                      (mh-coalesce-msg-list msg-list))
 237                              t))
 238            (when mh-index-data
 239              (mh-index-insert-folder-headers)
 240              (mh-notate-cur)))
 241           (t (mh-thread-folder)
 242              (push 'unthread mh-view-ops)))
 243     (when msg-at-point (mh-goto-msg msg-at-point t t))
 244     (set-buffer-modified-p old-buffer-modified-flag)
 245     (mh-recenter nil)))
 246
 247 \f
 248
 249 ;;; Support Routines
 250
 251 (defun mh-thread-current-indentation-level ()
 252   "Find the number of spaces by which current message is indented."
 253   (save-excursion
 254     (let ((address-start-offset (+ mh-cmd-note mh-scan-date-flag-width
 255                                    mh-scan-date-width 1))
 256           (level 0))
 257       (beginning-of-line)
 258       (forward-char address-start-offset)
 259       (while (char-equal (char-after) ? )
 260         (incf level)
 261         (forward-char))
 262       level)))
 263
 264 (defun mh-thread-immediate-ancestor ()
 265   "Jump to immediate ancestor in thread tree."
 266   (beginning-of-line)
 267   (let ((point (point))
 268         (ancestor-level (- (mh-thread-current-indentation-level) 2))
 269         (done nil))
 270     (if (< ancestor-level 0)
 271         nil
 272       (while (and (not done) (equal (forward-line -1) 0))
 273         (when (equal ancestor-level (mh-thread-current-indentation-level))
 274           (setq done t)))
 275       (unless done
 276         (goto-char point))
 277       done)))
 278
 279 (defun mh-thread-find-children ()
 280   "Return a region containing the current message and its children.
 281 The result is returned as a list of two elements. The first is
 282 the point at the start of the region and the second is the point
 283 at the end."
 284   (beginning-of-line)
 285   (if (eobp)
 286       nil
 287     (let ((address-start-offset (+ mh-cmd-note mh-scan-date-flag-width
 288                                    mh-scan-date-width 1))
 289           (level (mh-thread-current-indentation-level))
 290           spaces begin)
 291       (setq begin (point))
 292       (setq spaces (format (format "%%%ss" (1+ level)) ""))
 293       (forward-line)
 294       (block nil
 295         (while (not (eobp))
 296           (forward-char address-start-offset)
 297           (unless (equal (string-match spaces (buffer-substring-no-properties
 298                                                (point) (mh-line-end-position)))
 299                          0)
 300             (beginning-of-line)
 301             (backward-char)
 302             (return))
 303           (forward-line)))
 304       (list begin (point)))))
 305
 306 \f
 307
 308 ;;; Thread Creation
 309
 310 (defun mh-thread-folder ()
 311   "Generate thread view of folder."
 312   (message "Threading %s..." (buffer-name))
 313   (mh-thread-initialize)
 314   (goto-char (point-min))
 315   (mh-remove-all-notation)
 316   (let ((msg-list ()))
 317     (mh-iterate-on-range msg (cons (point-min) (point-max))
 318       (setf (gethash msg mh-thread-scan-line-map) (mh-thread-parse-scan-line))
 319       (push msg msg-list))
 320     (let* ((range (mh-coalesce-msg-list msg-list))
 321            (thread-tree (mh-thread-generate (buffer-name) range)))
 322       (delete-region (point-min) (point-max))
 323       (mh-thread-print-scan-lines thread-tree)
 324       (mh-notate-user-sequences)
 325       (mh-notate-deleted-and-refiled)
 326       (mh-notate-cur)
 327       (message "Threading %s...done" (buffer-name)))))
 328
 329 ;;;###mh-autoload
 330 (defun mh-thread-inc (folder start-point)
 331   "Update thread tree for FOLDER.
 332 All messages after START-POINT are added to the thread tree."
 333   (mh-thread-rewind-pruning)
 334   (mh-remove-all-notation)
 335   (goto-char start-point)
 336   (let ((msg-list ()))
 337     (while (not (eobp))
 338       (let ((index (mh-get-msg-num nil)))
 339         (when (numberp index)
 340           (push index msg-list)
 341           (setf (gethash index mh-thread-scan-line-map)
 342                 (mh-thread-parse-scan-line)))
 343         (forward-line)))
 344     (let ((thread-tree (mh-thread-generate folder msg-list))
 345           (buffer-read-only nil)
 346           (old-buffer-modified-flag (buffer-modified-p)))
 347       (delete-region (point-min) (point-max))
 348       (mh-thread-print-scan-lines thread-tree)
 349       (mh-notate-user-sequences)
 350       (mh-notate-deleted-and-refiled)
 351       (mh-notate-cur)
 352       (set-buffer-modified-p old-buffer-modified-flag))))
 353
 354 (defmacro mh-thread-initialize-hash (var test)
 355   "Initialize the hash table in VAR.
 356 TEST is the test to use when creating a new hash table."
 357   (unless (symbolp var) (error "Expected a symbol: %s" var))
 358   `(if ,var (clrhash ,var) (setq ,var (make-hash-table :test ,test))))
 359
 360 (defun mh-thread-initialize ()
 361   "Make new hash tables, or clear them if already present."
 362   (mh-thread-initialize-hash mh-thread-id-hash #'equal)
 363   (mh-thread-initialize-hash mh-thread-subject-hash #'equal)
 364   (mh-thread-initialize-hash mh-thread-id-table #'eq)
 365   (mh-thread-initialize-hash mh-thread-id-index-map #'eq)
 366   (mh-thread-initialize-hash mh-thread-index-id-map #'eql)
 367   (mh-thread-initialize-hash mh-thread-scan-line-map #'eql)
 368   (mh-thread-initialize-hash mh-thread-subject-container-hash #'eq)
 369   (mh-thread-initialize-hash mh-thread-duplicates #'eq)
 370   (setq mh-thread-history ()))
 371
 372 (defsubst mh-thread-id-container (id)
 373   "Given ID, return the corresponding container in `mh-thread-id-table'.
 374 If no container exists then a suitable container is created and
 375 the id-table is updated."
 376   (when (not id)
 377     (error "1"))
 378   (or (gethash id mh-thread-id-table)
 379       (setf (gethash id mh-thread-id-table)
 380             (let ((message (mh-thread-make-message :id id)))
 381               (mh-thread-make-container :message message)))))
 382
 383 (defsubst mh-thread-remove-parent-link (child)
 384   "Remove parent link of CHILD if it exists."
 385   (let* ((child-container (if (mh-thread-container-p child)
 386                               child (mh-thread-id-container child)))
 387          (parent-container (mh-container-parent child-container)))
 388     (when parent-container
 389       (setf (mh-container-children parent-container)
 390             (loop for elem in (mh-container-children parent-container)
 391                   unless (eq child-container elem) collect elem))
 392       (setf (mh-container-parent child-container) nil))))
 393
 394 (defsubst mh-thread-add-link (parent child &optional at-end-p)
 395   "Add links so that PARENT becomes a parent of CHILD.
 396 Doesn't make any changes if CHILD is already an ancestor of
 397 PARENT. If optional argument AT-END-P is non-nil, the CHILD is
 398 added to the end of the children list of PARENT."
 399   (let ((parent-container (cond ((null parent) nil)
 400                                 ((mh-thread-container-p parent) parent)
 401                                 (t (mh-thread-id-container parent))))
 402         (child-container (if (mh-thread-container-p child)
 403                              child (mh-thread-id-container child))))
 404     (when (and parent-container
 405                (not (mh-thread-ancestor-p child-container parent-container))
 406                (not (mh-thread-ancestor-p parent-container child-container)))
 407       (mh-thread-remove-parent-link child-container)
 408       (cond ((not at-end-p)
 409              (push child-container (mh-container-children parent-container)))
 410             ((null (mh-container-children parent-container))
 411              (push child-container (mh-container-children parent-container)))
 412             (t (let ((last-child (mh-container-children parent-container)))
 413                  (while (cdr last-child)
 414                    (setq last-child (cdr last-child)))
 415                  (setcdr last-child (cons child-container nil)))))
 416       (setf (mh-container-parent child-container) parent-container))
 417     (unless parent-container
 418       (mh-thread-remove-parent-link child-container))))
 419
 420 (defun mh-thread-rewind-pruning ()
 421   "Restore the thread tree to its state before pruning."
 422   (while mh-thread-history
 423     (let ((action (pop mh-thread-history)))
 424       (cond ((eq (car action) 'DROP)
 425              (mh-thread-remove-parent-link (cadr action))
 426              (mh-thread-add-link (caddr action) (cadr action)))
 427             ((eq (car action) 'PROMOTE)
 428              (let ((node (cadr action))
 429                    (parent (caddr action))
 430                    (children (cdddr action)))
 431                (dolist (child children)
 432                  (mh-thread-remove-parent-link child)
 433                  (mh-thread-add-link node child))
 434                (mh-thread-add-link parent node)))
 435             ((eq (car action) 'SUBJECT)
 436              (let ((node (cadr action)))
 437                (mh-thread-remove-parent-link node)
 438                (setf (mh-container-real-child-p node) t)))))))
 439
 440 (defun mh-thread-ancestor-p (ancestor successor)
 441   "Return t if ANCESTOR is really an ancestor of SUCCESSOR and nil otherwise.
 442 In the limit, the function returns t if ANCESTOR and SUCCESSOR
 443 are the same containers."
 444   (block nil
 445     (while successor
 446       (when (eq ancestor successor) (return t))
 447       (setq successor (mh-container-parent successor)))
 448     nil))
 449
 450 ;; Another and may be better approach would be to generate all the info from
 451 ;; the scan which generates the threading info. For now this will have to do.
 452 ;;;###mh-autoload
 453 (defun mh-thread-parse-scan-line (&optional string)
 454   "Parse a scan line.
 455 If optional argument STRING is given then that is assumed to be
 456 the scan line. Otherwise uses the line at point as the scan line
 457 to parse."
 458   (let* ((string (or string (buffer-substring-no-properties
 459                              (mh-line-beginning-position)
 460                              (mh-line-end-position))))
 461          (address-start (+ mh-cmd-note mh-scan-field-from-start-offset))
 462          (body-start (+ mh-cmd-note mh-scan-field-from-end-offset))
 463          (first-string (substring string 0 address-start)))
 464     (list first-string
 465           (substring string address-start (- body-start 2))
 466           (substring string body-start)
 467           string)))
 468
 469 (defsubst mh-thread-canonicalize-id (id)
 470   "Produce canonical string representation for ID.
 471 This allows cheap string comparison with EQ."
 472   (or (and (equal id "") (copy-sequence ""))
 473       (gethash id mh-thread-id-hash)
 474       (setf (gethash id mh-thread-id-hash) id)))
 475
 476 (defsubst mh-thread-prune-subject (subject)
 477   "Prune leading Re:'s, Fwd:'s etc. and trailing (fwd)'s from SUBJECT.
 478 If the result after pruning is not the empty string then it is
 479 canonicalized so that subjects can be tested for equality with
 480 eq. This is done so that all the messages without a subject are
 481 not put into a single thread."
 482   (let ((case-fold-search t)
 483         (subject-pruned-flag nil))
 484     ;; Prune subject leader
 485     (while (or (string-match "^[ \t]*\\(re\\|fwd?\\)\\(\\[[0-9]*\\]\\)?:[ \t]*"
 486                              subject)
 487                (string-match "^[ \t]*\\[[^\\]][ \t]*" subject))
 488       (setq subject-pruned-flag t)
 489       (setq subject (substring subject (match-end 0))))
 490     ;; Prune subject trailer
 491     (while (or (string-match "(fwd)$" subject)
 492                (string-match "[ \t]+$" subject))
 493       (setq subject-pruned-flag t)
 494       (setq subject (substring subject 0 (match-beginning 0))))
 495     ;; Canonicalize subject only if it is non-empty
 496     (cond ((equal subject "") (list subject subject-pruned-flag))
 497           (t (list
 498               (or (gethash subject mh-thread-subject-hash)
 499                   (setf (gethash subject mh-thread-subject-hash) subject))
 500               subject-pruned-flag)))))
 501
 502 (defsubst mh-thread-group-by-subject (roots)
 503   "Group the set of message containers, ROOTS based on subject.
 504 Bug: Check for and make sure that something without Re: is made
 505 the parent in preference to something that has it."
 506   (clrhash mh-thread-subject-container-hash)
 507   (let ((results ()))
 508     (dolist (root roots)
 509       (let* ((subject (mh-thread-container-subject root))
 510              (parent (gethash subject mh-thread-subject-container-hash)))
 511         (cond (parent (mh-thread-remove-parent-link root)
 512                       (mh-thread-add-link parent root t)
 513                       (setf (mh-container-real-child-p root) nil)
 514                       (push `(SUBJECT ,root) mh-thread-history))
 515               (t
 516                (setf (gethash subject mh-thread-subject-container-hash) root)
 517                (push root results)))))
 518     (nreverse results)))
 519
 520 (defun mh-thread-container-subject (container)
 521   "Return the subject of CONTAINER.
 522 If CONTAINER is empty return the subject info of one of its
 523 children."
 524   (cond ((and (mh-container-message container)
 525               (mh-message-id (mh-container-message container)))
 526          (mh-message-subject (mh-container-message container)))
 527         (t (block nil
 528              (dolist (kid (mh-container-children container))
 529                (when (and (mh-container-message kid)
 530                           (mh-message-id (mh-container-message kid)))
 531                  (let ((kid-message (mh-container-message kid)))
 532                    (return (mh-message-subject kid-message)))))
 533              (error "This can't happen")))))
 534
 535 (defsubst mh-thread-update-id-index-maps (id index)
 536   "Message with id, ID is the message in INDEX.
 537 The function also checks for duplicate messages (that is multiple
 538 messages with the same ID). These messages are put in the
 539 `mh-thread-duplicates' hash table."
 540   (let ((old-index (gethash id mh-thread-id-index-map)))
 541     (when old-index (push old-index (gethash id mh-thread-duplicates)))
 542     (setf (gethash id mh-thread-id-index-map) index)
 543     (setf (gethash index mh-thread-index-id-map) id)))
 544
 545 (defsubst mh-thread-get-message-container (message)
 546   "Return container which has MESSAGE in it.
 547 If there is no container present then a new container is
 548 allocated."
 549   (let* ((id (mh-message-id message))
 550          (container (gethash id mh-thread-id-table)))
 551     (cond (container (setf (mh-container-message container) message)
 552                      container)
 553           (t (setf (gethash id mh-thread-id-table)
 554                    (mh-thread-make-container :message message))))))
 555
 556 (defsubst mh-thread-get-message (id subject-re-p subject refs)
 557   "Return appropriate message.
 558 Otherwise update message already present to have the proper ID,
 559 SUBJECT-RE-P, SUBJECT and REFS fields."
 560   (let* ((container (gethash id mh-thread-id-table))
 561          (message (if container (mh-container-message container) nil)))
 562     (cond (message
 563            (setf (mh-message-subject-re-p message) subject-re-p)
 564            (setf (mh-message-subject message) subject)
 565            (setf (mh-message-id message) id)
 566            (setf (mh-message-references message) refs)
 567            message)
 568           (container
 569            (setf (mh-container-message container)
 570                  (mh-thread-make-message :id id :references refs
 571                                          :subject subject
 572                                          :subject-re-p subject-re-p)))
 573           (t (let ((message (mh-thread-make-message :id id :references refs
 574                                                     :subject-re-p subject-re-p
 575                                                     :subject subject)))
 576                (prog1 message
 577                  (mh-thread-get-message-container message)))))))
 578
 579 (defvar mh-message-id-regexp "^<.*@.*>$"
 580   "Regexp to recognize whether a string is a message identifier.")
 581
 582 ;;;###mh-autoload
 583 (defun mh-thread-generate (folder msg-list)
 584   "Scan FOLDER to get info for threading.
 585 Only information about messages in MSG-LIST are added to the tree."
 586   (with-temp-buffer
 587     (mh-thread-set-tables folder)
 588     (when msg-list
 589       (apply
 590        #'call-process (expand-file-name mh-scan-prog mh-progs) nil '(t nil) nil
 591        "-width" "10000" "-format"
 592        "%(msg)\n%{message-id}\n%{references}\n%{in-reply-to}\n%{subject}\n"
 593        folder (mapcar #'(lambda (x) (format "%s" x)) msg-list)))
 594     (goto-char (point-min))
 595     (let ((roots ())
 596           (case-fold-search t))
 597       (block nil
 598         (while (not (eobp))
 599           (block process-message
 600             (let* ((index-line
 601                     (prog1 (buffer-substring (point) (mh-line-end-position))
 602                       (forward-line)))
 603                    (index (string-to-number index-line))
 604                    (id (prog1 (buffer-substring (point) (mh-line-end-position))
 605                          (forward-line)))
 606                    (refs (prog1
 607                              (buffer-substring (point) (mh-line-end-position))
 608                            (forward-line)))
 609                    (in-reply-to (prog1 (buffer-substring (point)
 610                                                          (mh-line-end-position))
 611                                   (forward-line)))
 612                    (subject (prog1
 613                                 (buffer-substring
 614                                  (point) (mh-line-end-position))
 615                               (forward-line)))
 616                    (subject-re-p nil))
 617               (unless (gethash index mh-thread-scan-line-map)
 618                 (return-from process-message))
 619               (unless (integerp index) (return)) ;Error message here
 620               (multiple-value-setq (subject subject-re-p)
 621                 (values-list (mh-thread-prune-subject subject)))
 622               (setq in-reply-to (mh-thread-process-in-reply-to in-reply-to))
 623               (setq refs (loop for x in (append (split-string refs) in-reply-to)
 624                                when (string-match mh-message-id-regexp x)
 625                                collect x))
 626               (setq id (mh-thread-canonicalize-id id))
 627               (mh-thread-update-id-index-maps id index)
 628               (setq refs (mapcar #'mh-thread-canonicalize-id refs))
 629               (mh-thread-get-message id subject-re-p subject refs)
 630               (do ((ancestors refs (cdr ancestors)))
 631                   ((null (cdr ancestors))
 632                    (when (car ancestors)
 633                      (mh-thread-remove-parent-link id)
 634                      (mh-thread-add-link (car ancestors) id)))
 635                 (mh-thread-add-link (car ancestors) (cadr ancestors)))))))
 636       (maphash #'(lambda (k v)
 637                    (declare (ignore k))
 638                    (when (null (mh-container-parent v))
 639                      (push v roots)))
 640                mh-thread-id-table)
 641       (setq roots (mh-thread-prune-containers roots))
 642       (prog1 (setq roots (mh-thread-group-by-subject roots))
 643         (let ((history mh-thread-history))
 644           (set-buffer folder)
 645           (setq mh-thread-history history))))))
 646
 647 (defun mh-thread-set-tables (folder)
 648   "Use the tables of FOLDER in current buffer."
 649   (flet ((mh-get-table (symbol)
 650                        (with-current-buffer folder
 651                          (symbol-value symbol))))
 652     (setq mh-thread-id-hash (mh-get-table 'mh-thread-id-hash))
 653     (setq mh-thread-subject-hash (mh-get-table 'mh-thread-subject-hash))
 654     (setq mh-thread-id-table (mh-get-table 'mh-thread-id-table))
 655     (setq mh-thread-id-index-map (mh-get-table 'mh-thread-id-index-map))
 656     (setq mh-thread-index-id-map (mh-get-table 'mh-thread-index-id-map))
 657     (setq mh-thread-scan-line-map (mh-get-table 'mh-thread-scan-line-map))
 658     (setq mh-thread-subject-container-hash
 659           (mh-get-table 'mh-thread-subject-container-hash))
 660     (setq mh-thread-duplicates (mh-get-table 'mh-thread-duplicates))
 661     (setq mh-thread-history (mh-get-table 'mh-thread-history))))
 662
 663 (defun mh-thread-process-in-reply-to (reply-to-header)
 664   "Extract message id's from REPLY-TO-HEADER.
 665 Ideally this should have some regexp which will try to guess if a
 666 string between < and > is a message id and not an email address.
 667 For now it will take the last string inside angles."
 668   (let ((end (mh-search-from-end ?> reply-to-header)))
 669     (when (numberp end)
 670       (let ((begin (mh-search-from-end ?< (substring reply-to-header 0 end))))
 671         (when (numberp begin)
 672           (list (substring reply-to-header begin (1+ end))))))))
 673
 674 (defun mh-thread-prune-containers (roots)
 675   "Prune empty containers in the containers ROOTS."
 676   (let ((dfs-ordered-nodes ())
 677         (work-list roots))
 678     (while work-list
 679       (let ((node (pop work-list)))
 680         (dolist (child (mh-container-children node))
 681           (push child work-list))
 682         (push node dfs-ordered-nodes)))
 683     (while dfs-ordered-nodes
 684       (let ((node (pop dfs-ordered-nodes)))
 685         (cond ((gethash (mh-message-id (mh-container-message node))
 686                         mh-thread-id-index-map)
 687                ;; Keep it
 688                (setf (mh-container-children node)
 689                      (mh-thread-sort-containers (mh-container-children node))))
 690               ((and (mh-container-children node)
 691                     (or (null (cdr (mh-container-children node)))
 692                         (mh-container-parent node)))
 693                ;; Promote kids
 694                (let ((children ()))
 695                  (dolist (kid (mh-container-children node))
 696                    (mh-thread-remove-parent-link kid)
 697                    (mh-thread-add-link (mh-container-parent node) kid)
 698                    (push kid children))
 699                  (push `(PROMOTE ,node ,(mh-container-parent node) ,@children)
 700                        mh-thread-history)
 701                  (mh-thread-remove-parent-link node)))
 702               ((mh-container-children node)
 703                ;; Promote the first orphan to parent and add the other kids as
 704                ;; his children
 705                (setf (mh-container-children node)
 706                      (mh-thread-sort-containers (mh-container-children node)))
 707                (let ((new-parent (car (mh-container-children node)))
 708                      (other-kids (cdr (mh-container-children node))))
 709                  (mh-thread-remove-parent-link new-parent)
 710                  (dolist (kid other-kids)
 711                    (mh-thread-remove-parent-link kid)
 712                    (setf (mh-container-real-child-p kid) nil)
 713                    (mh-thread-add-link new-parent kid t))
 714                  (push `(PROMOTE ,node ,(mh-container-parent node)
 715                                  ,new-parent ,@other-kids)
 716                        mh-thread-history)
 717                  (mh-thread-remove-parent-link node)))
 718               (t
 719                ;; Drop it
 720                (push `(DROP ,node ,(mh-container-parent node))
 721                      mh-thread-history)
 722                (mh-thread-remove-parent-link node)))))
 723     (let ((results ()))
 724       (maphash #'(lambda (k v)
 725                    (declare (ignore k))
 726                    (when (and (null (mh-container-parent v))
 727                               (gethash (mh-message-id (mh-container-message v))
 728                                        mh-thread-id-index-map))
 729                      (push v results)))
 730                mh-thread-id-table)
 731       (mh-thread-sort-containers results))))
 732
 733 (defun mh-thread-sort-containers (containers)
 734   "Sort a list of message CONTAINERS to be in ascending order wrt index."
 735   (sort containers
 736         #'(lambda (x y)
 737             (when (and (mh-container-message x) (mh-container-message y))
 738               (let* ((id-x (mh-message-id (mh-container-message x)))
 739                      (id-y (mh-message-id (mh-container-message y)))
 740                      (index-x (gethash id-x mh-thread-id-index-map))
 741                      (index-y (gethash id-y mh-thread-id-index-map)))
 742                 (and (integerp index-x) (integerp index-y)
 743                      (< index-x index-y)))))))
 744
 745 (defvar mh-thread-last-ancestor)
 746
 747 ;;;###mh-autoload
 748 (defun mh-thread-print-scan-lines (thread-tree)
 749   "Print scan lines in THREAD-TREE in threaded mode."
 750   (let ((mh-thread-body-width (- (window-width) mh-cmd-note
 751                                  (1- mh-scan-field-subject-start-offset)))
 752         (mh-thread-last-ancestor nil))
 753     (if (null mh-index-data)
 754         (mh-thread-generate-scan-lines thread-tree -2)
 755       (loop for x in (mh-index-group-by-folder)
 756             do (let* ((old-map mh-thread-scan-line-map)
 757                       (mh-thread-scan-line-map (make-hash-table)))
 758                  (setq mh-thread-last-ancestor nil)
 759                  (loop for msg in (cdr x)
 760                        do (let ((v (gethash msg old-map)))
 761                             (when v
 762                               (setf (gethash msg mh-thread-scan-line-map) v))))
 763                  (when (> (hash-table-count mh-thread-scan-line-map) 0)
 764                    (insert (if (bobp) "" "\n") (car x) "\n")
 765                    (mh-thread-generate-scan-lines thread-tree -2))))
 766       (mh-index-create-imenu-index))))
 767
 768 (defun mh-thread-generate-scan-lines (tree level)
 769   "Generate scan lines.
 770 TREE is the hierarchical tree of messages, SCAN-LINE-MAP maps
 771 message indices to the corresponding scan lines and LEVEL used to
 772 determine indentation of the message."
 773   (cond ((null tree) nil)
 774         ((mh-thread-container-p tree)
 775          (let* ((message (mh-container-message tree))
 776                 (id (mh-message-id message))
 777                 (index (gethash id mh-thread-id-index-map))
 778                 (duplicates (gethash id mh-thread-duplicates))
 779                 (new-level (+ level 2))
 780                 (dupl-flag t)
 781                 (force-angle-flag nil)
 782                 (increment-level-flag nil))
 783            (dolist (scan-line (mapcar (lambda (x)
 784                                         (gethash x mh-thread-scan-line-map))
 785                                       (reverse (cons index duplicates))))
 786              (when scan-line
 787                (when (and dupl-flag (equal level 0)
 788                           (mh-thread-ancestor-p mh-thread-last-ancestor tree))
 789                  (setq level (+ level 2)
 790                        new-level (+ new-level 2)
 791                        force-angle-flag t))
 792                (when (equal level 0)
 793                  (setq mh-thread-last-ancestor tree)
 794                  (while (mh-container-parent mh-thread-last-ancestor)
 795                    (setq mh-thread-last-ancestor
 796                          (mh-container-parent mh-thread-last-ancestor))))
 797                (let* ((lev (if dupl-flag level new-level))
 798                       (square-flag (or (and (mh-container-real-child-p tree)
 799                                             (not force-angle-flag)
 800                                             dupl-flag)
 801                                        (equal lev 0))))
 802                  (insert (car scan-line)
 803                          (format (format "%%%ss" lev) "")
 804                          (if square-flag "[" "<")
 805                          (cadr scan-line)
 806                          (if square-flag "]" ">")
 807                          (truncate-string-to-width
 808                           (caddr scan-line) (- mh-thread-body-width lev))
 809                          "\n"))
 810                (setq increment-level-flag t)
 811                (setq dupl-flag nil)))
 812            (unless increment-level-flag (setq new-level level))
 813            (dolist (child (mh-container-children tree))
 814              (mh-thread-generate-scan-lines child new-level))))
 815         (t (let ((nlevel (+ level 2)))
 816              (dolist (ch tree)
 817                (mh-thread-generate-scan-lines ch nlevel))))))
 818
 819 \f
 820
 821 ;;; Additional Utilities
 822
 823 ;;;###mh-autoload
 824 (defun mh-thread-update-scan-line-map (msg notation offset)
 825   "In threaded view update `mh-thread-scan-line-map'.
 826 MSG is the message being notated with NOTATION at OFFSET."
 827   (let* ((msg (or msg (mh-get-msg-num nil)))
 828          (cur-scan-line (and mh-thread-scan-line-map
 829                              (gethash msg mh-thread-scan-line-map)))
 830          (old-scan-lines (loop for map in mh-thread-scan-line-map-stack
 831                                collect (and map (gethash msg map)))))
 832     (when cur-scan-line
 833       (setf (aref (car cur-scan-line) offset) notation))
 834     (dolist (line old-scan-lines)
 835       (when line (setf (aref (car line) offset) notation)))))
 836
 837 ;;;###mh-autoload
 838 (defun mh-thread-find-msg-subject (msg)
 839   "Find canonicalized subject of MSG.
 840 This function can only be used the folder is threaded."
 841   (ignore-errors
 842     (mh-message-subject
 843      (mh-container-message (gethash (gethash msg mh-thread-index-id-map)
 844                                     mh-thread-id-table)))))
 845
 846 ;;;###mh-autoload
 847 (defun mh-thread-add-spaces (count)
 848   "Add COUNT spaces to each scan line in `mh-thread-scan-line-map'."
 849   (let ((spaces (format (format "%%%ss" count) "")))
 850     (while (not (eobp))
 851       (let* ((msg-num (mh-get-msg-num nil))
 852              (old-line (nth 3 (gethash msg-num mh-thread-scan-line-map))))
 853         (when (numberp msg-num)
 854           (setf (gethash msg-num mh-thread-scan-line-map)
 855                 (mh-thread-parse-scan-line (format "%s%s" spaces old-line)))))
 856       (forward-line 1))))
 857
 858 ;;;###mh-autoload
 859 (defun mh-thread-forget-message (index)
 860   "Forget the message INDEX from the threading tables."
 861   (let* ((id (gethash index mh-thread-index-id-map))
 862          (id-index (gethash id mh-thread-id-index-map))
 863          (duplicates (gethash id mh-thread-duplicates)))
 864     (remhash index mh-thread-index-id-map)
 865     (remhash index mh-thread-scan-line-map)
 866     (cond ((and (eql index id-index) (null duplicates))
 867            (remhash id mh-thread-id-index-map))
 868           ((eql index id-index)
 869            (setf (gethash id mh-thread-id-index-map) (car duplicates))
 870            (setf (gethash (car duplicates) mh-thread-index-id-map) id)
 871            (setf (gethash id mh-thread-duplicates) (cdr duplicates)))
 872           (t
 873            (setf (gethash id mh-thread-duplicates)
 874                  (remove index duplicates))))))
 875
 876 (provide 'mh-thread)
 877
 878 ;; Local Variables:
 879 ;; indent-tabs-mode: nil
 880 ;; sentence-end-double-space: nil
 881 ;; End:
 882
 883 ;;; mh-thread.el ends here