aboutsummaryrefslogtreecommitdiffstats
path: root/lisp/emacs-lisp/ewoc.el
blob: a2cb4e9fe460ff0d980f06e57b3d7a4928e8b029 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
;;; ewoc.el --- utility to maintain a view of a list of objects in a buffer

;; Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 04
;;      Free Software Foundation

;; Author: Per Cederqvist <[email protected]>
;;	Inge Wallin <[email protected]>
;; Maintainer: [email protected]
;; Created: 3 Aug 1992
;; Keywords: extensions, lisp

;; This file is part of GNU Emacs.

;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Commentary:

;; Ewoc Was Once Cookie
;; But now it's Emacs' Widget for Object Collections

;; As the name implies this derives from the `cookie' package (part
;; of Elib).  The changes are pervasive though mostly superficial:

;; - uses CL (and its `defstruct')
;; - separate from Elib.
;; - uses its own version of a doubly-linked list which allows us
;;   to merge the elib-wrapper and the elib-node structures into ewoc-node
;; - dropping functions not used by PCL-CVS (the only client of ewoc at the
;;   time of writing)
;; - removing unused arguments
;; - renaming:
;;   elib-node	==>  ewoc--node
;;   collection ==>  ewoc
;;   tin 	==>  ewoc--node
;;   cookie 	==>  data or element or elem

;;     Introduction
;;     ============
;;
;; Ewoc is a package that implements a connection between an
;; dll (a doubly linked list) and the contents of a buffer.
;; Possible uses are dired (have all files in a list, and show them),
;; buffer-list, kom-prioritize (in the LysKOM elisp client) and
;; others.  pcl-cvs.el uses ewoc.el.
;;
;; Ewoc can be considered as the `view' part of a model-view-controller.
;;
;; A `element' can be any lisp object.  When you use the ewoc
;; package you specify a pretty-printer, a function that inserts
;; a printable representation of the element in the buffer.  (The
;; pretty-printer should use "insert" and not
;; "insert-before-markers").
;;
;; A `ewoc' consists of a doubly linked list of elements, a
;; header, a footer and a pretty-printer.  It is displayed at a
;; certain point in a certain buffer.  (The buffer and point are
;; fixed when the ewoc is created).  The header and the footer
;; are constant strings.  They appear before and after the elements.
;;
;; Ewoc does not affect the mode of the buffer in any way. It
;; merely makes it easy to connect an underlying data representation
;; to the buffer contents.
;;
;; A `ewoc--node' is an object that contains one element.  There are
;; functions in this package that given an ewoc--node extract the data, or
;; give the next or previous ewoc--node.  (All ewoc--nodes are linked together
;; in a doubly linked list.  The `previous' ewoc--node is the one that appears
;; before the other in the buffer.)  You should not do anything with
;; an ewoc--node except pass it to the functions in this package.
;;
;; An ewoc is a very dynamic thing.  You can easily add or delete elements.
;; You can apply a function to all elements in an ewoc, etc, etc.
;;
;; Remember that an element can be anything.  Your imagination is the
;; limit!  It is even possible to have another ewoc as an
;; element.  In that way some kind of tree hierarchy can be created.
;;
;; Full documentation will, God willing, soon be available in a
;; Texinfo manual.

;; In the mean time `grep '^(.*ewoc-[^-]' emacs-lisp/ewoc.el' can help
;; you find all the exported functions:
;;
;; (defun ewoc-create (pretty-printer &optional header footer)
;; (defalias 'ewoc-data 'ewoc--node-data)
;; (defun ewoc-location (node)
;; (defun ewoc-enter-first (ewoc data)
;; (defun ewoc-enter-last (ewoc data)
;; (defun ewoc-enter-after (ewoc node data)
;; (defun ewoc-enter-before (ewoc node data)
;; (defun ewoc-next (ewoc node)
;; (defun ewoc-prev (ewoc node)
;; (defun ewoc-nth (ewoc n)
;; (defun ewoc-map (map-function ewoc &rest args)
;; (defun ewoc-filter (ewoc predicate &rest args)
;; (defun ewoc-locate (ewoc &optional pos guess)
;; (defun ewoc-invalidate (ewoc &rest nodes)
;; (defun ewoc-goto-prev (ewoc arg)
;; (defun ewoc-goto-next (ewoc arg)
;; (defun ewoc-goto-node (ewoc node)
;; (defun ewoc-refresh (ewoc)
;; (defun ewoc-collect (ewoc predicate &rest args)
;; (defun ewoc-buffer (ewoc)
;; (defun ewoc-get-hf (ewoc)
;; (defun ewoc-set-hf (ewoc header footer)

;;     Coding conventions
;;     ==================
;;
;; All functions of course start with `ewoc'.  Functions and macros
;; starting with the prefix `ewoc--' are meant for internal use,
;; while those starting with `ewoc-' are exported for public use.
;; There are currently no global or buffer-local variables used.


;;; Code:

(eval-when-compile (require 'cl))	;because of CL compiler macros

;; The doubly linked list is implemented as a circular list
;; with a dummy node first and last. The dummy node is used as
;; "the dll" (or rather is the dll handle passed around).

(defstruct (ewoc--node
	    (:type vector)		;required for ewoc--node-branch hack
	    (:constructor ewoc--node-create (start-marker data)))
  left right data start-marker)

(defalias 'ewoc--node-branch 'aref
  "Get the left (CHILD=0) or right (CHILD=1) child of the NODE.

\(fn NODE CHILD)")

(defun ewoc--dll-create ()
  "Create an empty doubly linked list."
  (let ((dummy-node (ewoc--node-create 'DL-LIST 'DL-LIST)))
    (setf (ewoc--node-right dummy-node) dummy-node)
    (setf (ewoc--node-left dummy-node) dummy-node)
    dummy-node))

(defun ewoc--node-enter-before (node elemnode)
  "Insert ELEMNODE before NODE in a DLL."
  (assert (and (null (ewoc--node-left elemnode)) (null (ewoc--node-right elemnode))))
  (setf (ewoc--node-left elemnode) (ewoc--node-left node))
  (setf (ewoc--node-right elemnode) node)
  (setf (ewoc--node-right (ewoc--node-left node)) elemnode)
  (setf (ewoc--node-left node) elemnode))

(defun ewoc--node-enter-first (dll node)
  "Add a free floating NODE first in DLL."
  (ewoc--node-enter-before (ewoc--node-right dll) node))

(defun ewoc--node-enter-last (dll node)
  "Add a free floating NODE last in DLL."
  (ewoc--node-enter-before dll node))

(defun ewoc--node-next (dll node)
  "Return the node after NODE, or nil if NODE is the last node."
  (unless (eq (ewoc--node-right node) dll) (ewoc--node-right node)))

(defun ewoc--node-prev (dll node)
  "Return the node before NODE, or nil if NODE is the first node."
  (unless (eq (ewoc--node-left node) dll) (ewoc--node-left node)))

(defun ewoc--node-delete (node)
  "Unbind NODE from its doubly linked list and return it."
  ;; This is a no-op when applied to the dummy node. This will return
  ;; nil if applied to the dummy node since it always contains nil.
  (setf (ewoc--node-right (ewoc--node-left node)) (ewoc--node-right node))
  (setf (ewoc--node-left (ewoc--node-right node)) (ewoc--node-left node))
  (setf (ewoc--node-left node) nil)
  (setf (ewoc--node-right node) nil)
  node)

(defun ewoc--node-nth (dll n)
  "Return the Nth node from the doubly linked list DLL.
N counts from zero. If DLL is not that long, nil is returned.
If N is negative, return the -(N+1)th last element.
Thus, (ewoc--node-nth dll 0) returns the first node,
and (ewoc--node-nth dll -1) returns the last node."
  ;; Branch 0 ("follow left pointer") is used when n is negative.
  ;; Branch 1 ("follow right pointer") is used otherwise.
  (let* ((branch (if (< n 0) 0 1))
	 (node   (ewoc--node-branch dll branch)))
    (if (< n 0) (setq n (- -1 n)))
    (while (and (not (eq dll node)) (> n 0))
      (setq node (ewoc--node-branch node branch))
      (setq n (1- n)))
    (unless (eq dll node) node)))

(defun ewoc-location (node)
  "Return the start location of NODE."
  (ewoc--node-start-marker node))


;;; The ewoc data type

(defstruct (ewoc
	    (:constructor nil)
	    (:constructor ewoc--create
			  (buffer pretty-printer header footer dll))
	    (:conc-name ewoc--))
  buffer pretty-printer header footer dll last-node)

(defmacro ewoc--set-buffer-bind-dll-let* (ewoc varlist &rest forms)
  "Execute FORMS with ewoc--buffer selected as current buffer,
dll bound to ewoc--dll, and VARLIST bound as in a let*.
dll will be bound when VARLIST is initialized, but the current
buffer will *not* have been changed.
Return value of last form in FORMS."
  (let ((old-buffer (make-symbol "old-buffer"))
	(hnd (make-symbol "ewoc")))
    `(let* ((,old-buffer (current-buffer))
            (,hnd ,ewoc)
            (dll (ewoc--dll ,hnd))
            ,@varlist)
      (set-buffer (ewoc--buffer ,hnd))
      (unwind-protect
           (progn ,@forms)
        (set-buffer ,old-buffer)))))

(defmacro ewoc--set-buffer-bind-dll (ewoc &rest forms)
  `(ewoc--set-buffer-bind-dll-let* ,ewoc nil ,@forms))

(defsubst ewoc--filter-hf-nodes (ewoc node)
  "Evaluate NODE once and return it.
BUT if it is the header or the footer in EWOC return nil instead."
  (unless (or (eq node (ewoc--header ewoc))
	      (eq node (ewoc--footer ewoc)))
    node))


(defun ewoc--create-node (data pretty-printer pos)
  "Call PRETTY-PRINTER with point set at POS in current buffer.
Remember the start position.  Create a wrapper containing that
start position and the element DATA."
  (save-excursion
    ;; Remember the position as a number so that it doesn't move
    ;; when we insert the string.
    (when (markerp pos) (setq pos (marker-position pos)))
    (goto-char pos)
    (let ((inhibit-read-only t))
      ;; Insert the trailing newline using insert-before-markers
      ;; so that the start position for the next element is updated.
      (insert-before-markers ?\n)
      ;; Move back, and call the pretty-printer.
      (backward-char 1)
      (funcall pretty-printer data)
      (ewoc--node-create (copy-marker pos) data))))


(defun ewoc--delete-node-internal (ewoc node)
  "Delete a data string from EWOC.
Can not be used on the footer.  Returns the wrapper that is deleted.
The start-marker in the wrapper is set to nil, so that it doesn't
consume any more resources."
  (let ((dll (ewoc--dll ewoc))
	(inhibit-read-only t))
    ;; If we are about to delete the node pointed at by last-node,
    ;; set last-node to nil.
    (if (eq (ewoc--last-node ewoc) node)
	(setf (ewoc--last-node ewoc) nil))

    (delete-region (ewoc--node-start-marker node)
		   (ewoc--node-start-marker (ewoc--node-next dll node)))
    (set-marker (ewoc--node-start-marker node) nil)
    ;; Delete the node, and return the wrapper.
    (ewoc--node-delete node)))


(defun ewoc--refresh-node (pp node)
  "Redisplay the element represented by NODE using the pretty-printer PP."
  (let ((inhibit-read-only t))
    (save-excursion
      ;; First, remove the string from the buffer:
      (delete-region (ewoc--node-start-marker node)
		     (1- (marker-position
			  (ewoc--node-start-marker (ewoc--node-right node)))))
      ;; Calculate and insert the string.
      (goto-char (ewoc--node-start-marker node))
      (funcall pp (ewoc--node-data node)))))

;;; ===========================================================================
;;;                  Public members of the Ewoc package


(defun ewoc-create (pretty-printer &optional header footer)
  "Create an empty ewoc.

The ewoc will be inserted in the current buffer at the current position.

PRETTY-PRINTER should be a function that takes one argument, an
element, and inserts a string representing it in the buffer (at
point).  The string PRETTY-PRINTER inserts may be empty or span
several lines.  A trailing newline will always be inserted
automatically.  The PRETTY-PRINTER should use `insert', and not
`insert-before-markers'.

Optional second argument HEADER is a string that will always be
present at the top of the ewoc.  HEADER should end with a
newline.  Optional third argument FOOTER is similar, and will
be inserted at the bottom of the ewoc."
  (let ((new-ewoc
	 (ewoc--create (current-buffer)
		       pretty-printer nil nil (ewoc--dll-create)))
	(pos (point)))
    (ewoc--set-buffer-bind-dll new-ewoc
      ;; Set default values
      (unless header (setq header ""))
      (unless footer (setq footer ""))
      (setf (ewoc--node-start-marker dll) (copy-marker pos))
      (let ((foot (ewoc--create-node footer (lambda (x) (insert footer)) pos))
	    (head (ewoc--create-node header (lambda (x) (insert header)) pos)))
	(ewoc--node-enter-first dll head)
	(ewoc--node-enter-last  dll foot)
	(setf (ewoc--header new-ewoc) head)
	(setf (ewoc--footer new-ewoc) foot)))
    ;; Return the ewoc
    new-ewoc))

(defalias 'ewoc-data 'ewoc--node-data)

(defun ewoc-enter-first (ewoc data)
  "Enter DATA first in EWOC."
  (ewoc--set-buffer-bind-dll ewoc
    (ewoc-enter-after ewoc (ewoc--node-nth dll 0) data)))

(defun ewoc-enter-last (ewoc data)
  "Enter DATA last in EWOC."
  (ewoc--set-buffer-bind-dll ewoc
    (ewoc-enter-before ewoc (ewoc--node-nth dll -1) data)))


(defun ewoc-enter-after (ewoc node data)
  "Enter a new element DATA after NODE in EWOC.
Returns the new NODE."
  (ewoc--set-buffer-bind-dll ewoc
    (ewoc-enter-before ewoc (ewoc--node-next dll node) data)))

(defun ewoc-enter-before (ewoc node data)
  "Enter a new element DATA before NODE in EWOC.
Returns the new NODE."
  (ewoc--set-buffer-bind-dll ewoc
    (ewoc--node-enter-before
     node
     (ewoc--create-node
      data
      (ewoc--pretty-printer ewoc)
      (ewoc--node-start-marker node)))))

(defun ewoc-next (ewoc node)
  "Get the next node.
Returns nil if NODE is nil or the last element."
  (when node
    (ewoc--filter-hf-nodes
     ewoc (ewoc--node-next (ewoc--dll ewoc) node))))

(defun ewoc-prev (ewoc node)
  "Get the previous node.
Returns nil if NODE is nil or the first element."
  (when node
    (ewoc--filter-hf-nodes
     ewoc
     (ewoc--node-prev (ewoc--dll ewoc) node))))


(defun ewoc-nth (ewoc n)
  "Return the Nth node.
N counts from zero.  Return nil if there is less than N elements.
If N is negative, return the -(N+1)th last element.
Thus, (ewoc-nth dll 0) returns the first node,
and (ewoc-nth dll -1) returns the last node.
Use `ewoc--node-data' to extract the data from the node."
  ;; Skip the header (or footer, if n is negative).
  (setq n (if (< n 0) (1- n) (1+ n)))
  (ewoc--filter-hf-nodes ewoc
		  (ewoc--node-nth (ewoc--dll ewoc) n)))

(defun ewoc-map (map-function ewoc &rest args)
  "Apply MAP-FUNCTION to all elements in EWOC.
MAP-FUNCTION is applied to the first element first.
If MAP-FUNCTION returns non-nil the element will be refreshed (its
pretty-printer will be called once again).

Note that the buffer for EWOC will be the current buffer when
MAP-FUNCTION is called.  MAP-FUNCTION must restore the current
buffer before it returns, if it changes it.

If more than two arguments are given, the remaining
arguments will be passed to MAP-FUNCTION."
  (ewoc--set-buffer-bind-dll-let* ewoc
      ((footer (ewoc--footer ewoc))
       (node (ewoc--node-nth dll 1)))
    (while (not (eq node footer))
      (if (apply map-function (ewoc--node-data node) args)
	  (ewoc--refresh-node (ewoc--pretty-printer ewoc) node))
      (setq node (ewoc--node-next dll node)))))

(defun ewoc-filter (ewoc predicate &rest args)
  "Remove all elements in EWOC for which PREDICATE returns nil.
Note that the buffer for EWOC will be current-buffer when PREDICATE
is called.  PREDICATE must restore the current buffer before it returns
if it changes it.
The PREDICATE is called with the element as its first argument.  If any
ARGS are given they will be passed to the PREDICATE."
  (ewoc--set-buffer-bind-dll-let* ewoc
      ((node (ewoc--node-nth dll 1))
       (footer (ewoc--footer ewoc))
       (next nil))
    (while (not (eq node footer))
      (setq next (ewoc--node-next dll node))
      (unless (apply predicate (ewoc--node-data node) args)
	(ewoc--delete-node-internal ewoc node))
      (setq node next))))

(defun ewoc-locate (ewoc &optional pos guess)
  "Return the node that POS (a buffer position) is within.
POS may be a marker or an integer.  It defaults to point.
GUESS should be a node that it is likely to be near POS.

If POS points before the first element, the first node is returned.
If POS points after the last element, the last node is returned.
If the EWOC is empty, nil is returned."
  (unless pos (setq pos (point)))
  (ewoc--set-buffer-bind-dll-let* ewoc
      ((footer (ewoc--footer ewoc)))

    (cond
     ;; Nothing present?
     ((eq (ewoc--node-nth dll 1) (ewoc--node-nth dll -1))
      nil)

     ;; Before second elem?
     ((< pos (ewoc--node-start-marker (ewoc--node-nth dll 2)))
      (ewoc--node-nth dll 1))

     ;; After one-before-last elem?
     ((>= pos (ewoc--node-start-marker (ewoc--node-nth dll -2)))
      (ewoc--node-nth dll -2))

     ;; We now know that pos is within a elem.
     (t
      ;; Make an educated guess about which of the three known
      ;; node'es (the first, the last, or GUESS) is nearest.
      (let* ((best-guess (ewoc--node-nth dll 1))
	     (distance (abs (- pos (ewoc--node-start-marker best-guess)))))
	(when guess
	  (let ((d (abs (- pos (ewoc--node-start-marker guess)))))
	    (when (< d distance)
	      (setq distance d)
	      (setq best-guess guess))))

	(let* ((g (ewoc--node-nth dll -1))	;Check the last elem
	       (d (abs (- pos (ewoc--node-start-marker g)))))
	  (when (< d distance)
	    (setq distance d)
	    (setq best-guess g)))

	(when (ewoc--last-node ewoc) ;Check "previous".
	  (let* ((g (ewoc--last-node ewoc))
		 (d (abs (- pos (ewoc--node-start-marker g)))))
	    (when (< d distance)
	      (setq distance d)
	      (setq best-guess g))))

	;; best-guess is now a "best guess".
	;; Find the correct node. First determine in which direction
	;; it lies, and then move in that direction until it is found.

	(cond
	 ;; Is pos after the guess?
	 ((>= pos
	      (ewoc--node-start-marker best-guess))
	  ;; Loop until we are exactly one node too far down...
	  (while (>= pos (ewoc--node-start-marker best-guess))
	    (setq best-guess (ewoc--node-next dll best-guess)))
	  ;; ...and return the previous node.
	  (ewoc--node-prev dll best-guess))

	 ;; Pos is before best-guess
	 (t
	  (while (< pos (ewoc--node-start-marker best-guess))
	    (setq best-guess (ewoc--node-prev dll best-guess)))
	  best-guess)))))))

(defun ewoc-invalidate (ewoc &rest nodes)
  "Refresh some elements.
The pretty-printer set for EWOC will be called for all NODES."
  (ewoc--set-buffer-bind-dll ewoc
    (dolist (node nodes)
      (ewoc--refresh-node (ewoc--pretty-printer ewoc) node))))

(defun ewoc-goto-prev (ewoc arg)
  "Move point to the ARGth previous element.
Don't move if we are at the first element, or if EWOC is empty.
Returns the node we moved to."
  (ewoc--set-buffer-bind-dll-let* ewoc
      ((node (ewoc-locate ewoc (point))))
    (when node
      ;; If we were past the last element, first jump to it.
      (when (>= (point) (ewoc--node-start-marker (ewoc--node-right node)))
	(setq arg (1- arg)))
      (while (and node (> arg 0))
	(setq arg (1- arg))
	(setq node (ewoc--node-prev dll node)))
      ;; Never step above the first element.
      (unless (ewoc--filter-hf-nodes ewoc node)
	(setq node (ewoc--node-nth dll 1)))
      (ewoc-goto-node ewoc node))))

(defun ewoc-goto-next (ewoc arg)
  "Move point to the ARGth next element.
Returns the node (or nil if we just passed the last node)."
  (ewoc--set-buffer-bind-dll-let* ewoc
      ((node (ewoc-locate ewoc (point))))
    (while (and node (> arg 0))
      (setq arg (1- arg))
      (setq node (ewoc--node-next dll node)))
    ;; Never step below the first element.
    ;; (unless (ewoc--filter-hf-nodes ewoc node)
    ;;   (setq node (ewoc--node-nth dll -2)))
    (ewoc-goto-node ewoc node)))

(defun ewoc-goto-node (ewoc node)
  "Move point to NODE."
  (ewoc--set-buffer-bind-dll ewoc
    (goto-char (ewoc--node-start-marker node))
    (if goal-column (move-to-column goal-column))
    (setf (ewoc--last-node ewoc) node)))

(defun ewoc-refresh (ewoc)
  "Refresh all data in EWOC.
The pretty-printer that was specified when the EWOC was created
will be called for all elements in EWOC.
Note that `ewoc-invalidate' is more efficient if only a small
number of elements needs to be refreshed."
  (ewoc--set-buffer-bind-dll-let* ewoc
      ((footer (ewoc--footer ewoc)))
    (let ((inhibit-read-only t))
      (delete-region (ewoc--node-start-marker (ewoc--node-nth dll 1))
		     (ewoc--node-start-marker footer))
      (goto-char (ewoc--node-start-marker footer))
      (let ((node (ewoc--node-nth dll 1)))
	(while (not (eq node footer))
	  (set-marker (ewoc--node-start-marker node) (point))
	  (funcall (ewoc--pretty-printer ewoc)
		   (ewoc--node-data node))
	  (insert "\n")
	  (setq node (ewoc--node-next dll node)))))
    (set-marker (ewoc--node-start-marker footer) (point))))

(defun ewoc-collect (ewoc predicate &rest args)
  "Select elements from EWOC using PREDICATE.
Return a list of all selected data elements.
PREDICATE is a function that takes a data element as its first
argument.  The elements on the returned list will appear in the
same order as in the buffer.  You should not rely on the order of
calls to PREDICATE.
Note that the buffer the EWOC is displayed in is the current
buffer when PREDICATE is called.  PREDICATE must restore it if it
changes it.
If more than two arguments are given the
remaining arguments will be passed to PREDICATE."
  (ewoc--set-buffer-bind-dll-let* ewoc
      ((header (ewoc--header ewoc))
       (node (ewoc--node-nth dll -2))
       result)
    (while (not (eq node header))
      (if (apply predicate (ewoc--node-data node) args)
	  (push (ewoc--node-data node) result))
      (setq node (ewoc--node-prev dll node)))
    (nreverse result)))

(defun ewoc-buffer (ewoc)
  "Return the buffer that is associated with EWOC.
Returns nil if the buffer has been deleted."
  (let ((buf (ewoc--buffer ewoc)))
    (when (buffer-name buf) buf)))

(defun ewoc-get-hf (ewoc)
  "Return a cons cell containing the (HEADER . FOOTER) of EWOC."
  (cons (ewoc--node-data (ewoc--header ewoc))
	(ewoc--node-data (ewoc--footer ewoc))))

(defun ewoc-set-hf (ewoc header footer)
  "Set the HEADER and FOOTER of EWOC."
  (setf (ewoc--node-data (ewoc--header ewoc)) header)
  (setf (ewoc--node-data (ewoc--footer ewoc)) footer)
  (ewoc--refresh-node (lambda (x) (insert header)) (ewoc--header ewoc))
  (ewoc--refresh-node (lambda (x) (insert footer)) (ewoc--footer ewoc)))


(provide 'ewoc)

;;; Local Variables:
;;; eval: (put 'ewoc--set-buffer-bind-dll 'lisp-indent-hook 1)
;;; eval: (put 'ewoc--set-buffer-bind-dll-let* 'lisp-indent-hook 2)
;;; End:

;;; arch-tag: d78915b9-9a07-44bf-aac6-04a1fc1bd6d4
;;; ewoc.el ends here