summaryrefslogtreecommitdiffstats
path: root/accessible/generic/DocAccessible.h
blob: 791d09661e45e851d11a6ccdcc5f9624de89da3e (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
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_a11y_DocAccessible_h__
#define mozilla_a11y_DocAccessible_h__

#include "HyperTextAccessible.h"
#include "AccEvent.h"

#include "nsClassHashtable.h"
#include "nsTHashMap.h"
#include "mozilla/UniquePtr.h"
#include "nsIDocumentObserver.h"
#include "nsITimer.h"
#include "nsTHashSet.h"
#include "nsWeakReference.h"

const uint32_t kDefaultCacheLength = 128;

namespace mozilla {

class EditorBase;
class PresShell;

namespace dom {
class Document;
}

namespace a11y {

class DocManager;
class NotificationController;
class DocAccessibleChild;
class RelatedAccIterator;
template <class Class, class... Args>
class TNotification;

/**
 * An accessibility tree node that originated in a content process and
 * represents a document. Tabs, in-process iframes, and out-of-process iframes
 * all use this class to represent the doc they contain.
 */
class DocAccessible : public HyperTextAccessible,
                      public nsIDocumentObserver,
                      public nsSupportsWeakReference {
  NS_DECL_ISUPPORTS_INHERITED
  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(DocAccessible, LocalAccessible)

 protected:
  typedef mozilla::dom::Document Document;

 public:
  DocAccessible(Document* aDocument, PresShell* aPresShell);

  // nsIDocumentObserver
  NS_DECL_NSIDOCUMENTOBSERVER

  // LocalAccessible
  virtual void Init();
  virtual void Shutdown() override;
  virtual nsIFrame* GetFrame() const override;
  virtual nsINode* GetNode() const override;
  Document* DocumentNode() const { return mDocumentNode; }

  virtual mozilla::a11y::ENameValueFlag Name(nsString& aName) const override;
  virtual void Description(nsString& aDescription) const override;
  virtual Accessible* FocusedChild() override;
  virtual mozilla::a11y::role NativeRole() const override;
  virtual uint64_t NativeState() const override;
  virtual uint64_t NativeInteractiveState() const override;
  virtual bool NativelyUnavailable() const override;
  virtual void ApplyARIAState(uint64_t* aState) const override;

  virtual void TakeFocus() const override;

#ifdef A11Y_LOG
  virtual nsresult HandleAccEvent(AccEvent* aEvent) override;
#endif

  virtual nsRect RelativeBounds(nsIFrame** aRelativeFrame) const override;

  // ActionAccessible
  virtual bool HasPrimaryAction() const override;
  virtual void ActionNameAt(uint8_t aIndex, nsAString& aName) override;

  // HyperTextAccessible
  virtual already_AddRefed<EditorBase> GetEditor() const override;

  // DocAccessible

  /**
   * Return document URL.
   */
  void URL(nsAString& aURL) const;

  /**
   * Return DOM document title.
   */
  void Title(nsString& aTitle) const;

  /**
   * Return DOM document mime type.
   */
  void MimeType(nsAString& aType) const;
  /**
   * Return DOM document type.
   */
  void DocType(nsAString& aType) const;

  /**
   * Adds an entry to queued cache updates indicating aAcc requires
   * a cache update on domain aNewDomain. If we've already queued an update
   * for aAcc, aNewDomain is or'd with the existing domain(s)
   * and the map is updated. Otherwise, the entry is simply inserted.
   * This function also schedules processing on the controller.
   * Note that this CANNOT be used for anything which fires events, since events
   * must be fired after their associated cache update.
   */
  void QueueCacheUpdate(LocalAccessible* aAcc, uint64_t aNewDomain);

  /**
   * Walks the dependent ids and elements maps for the given accessible and
   * queues a CacheDomain::Relations cache update fore each related acc.
   * We call this when we observe an ID mutation or when an acc is bound
   * to its document.
   */
  void QueueCacheUpdateForDependentRelations(LocalAccessible* aAcc);

  /**
   * Returns true if the instance has shutdown.
   */
  bool HasShutdown() const { return !mPresShell; }

  /**
   * Return presentation shell for this document accessible.
   */
  PresShell* PresShellPtr() const {
    MOZ_DIAGNOSTIC_ASSERT(!HasShutdown());
    return mPresShell;
  }

  /**
   * Return the presentation shell's context.
   */
  nsPresContext* PresContext() const;

  /**
   * Return true if associated DOM document was loaded and isn't unloading.
   */
  bool IsContentLoaded() const;

  bool IsHidden() const;

  void SetViewportCacheDirty(bool aDirty) { mViewportCacheDirty = aDirty; }

  /**
   * Document load states.
   */
  enum LoadState {
    // initial tree construction is pending
    eTreeConstructionPending = 0,
    // initial tree construction done
    eTreeConstructed = 1,
    // DOM document is loaded.
    eDOMLoaded = 1 << 1,
    // document is ready
    eReady = eTreeConstructed | eDOMLoaded,
    // document and all its subdocuments are ready
    eCompletelyLoaded = eReady | 1 << 2
  };

  /**
   * Return true if the document has given document state.
   */
  bool HasLoadState(LoadState aState) const {
    return (mLoadState & static_cast<uint32_t>(aState)) ==
           static_cast<uint32_t>(aState);
  }

  /**
   * Return a native window handler or pointer depending on platform.
   */
  virtual void* GetNativeWindow() const;

  /**
   * Return the parent document.
   */
  DocAccessible* ParentDocument() const {
    return mParent ? mParent->Document() : nullptr;
  }

  /**
   * Return the child document count.
   */
  uint32_t ChildDocumentCount() const { return mChildDocuments.Length(); }

  /**
   * Return the child document at the given index.
   */
  DocAccessible* GetChildDocumentAt(uint32_t aIndex) const {
    return mChildDocuments.SafeElementAt(aIndex, nullptr);
  }

  /**
   * Fire accessible event asynchronously.
   */
  void FireDelayedEvent(AccEvent* aEvent);
  void FireDelayedEvent(uint32_t aEventType, LocalAccessible* aTarget);
  void FireEventsOnInsertion(LocalAccessible* aContainer);

  /**
   * Fire value change event on the given accessible if applicable.
   */
  void MaybeNotifyOfValueChange(LocalAccessible* aAccessible);

  /**
   * Get/set the anchor jump.
   */
  LocalAccessible* AnchorJump() {
    return GetAccessibleOrContainer(mAnchorJumpElm);
  }

  void SetAnchorJump(nsIContent* aTargetNode) { mAnchorJumpElm = aTargetNode; }

  /**
   * Bind the child document to the tree.
   */
  void BindChildDocument(DocAccessible* aDocument);

  /**
   * Process the generic notification.
   *
   * @note  The caller must guarantee that the given instance still exists when
   *          notification is processed.
   * @see   NotificationController::HandleNotification
   */
  template <class Class, class... Args>
  void HandleNotification(
      Class* aInstance,
      typename TNotification<Class, Args...>::Callback aMethod, Args*... aArgs);

  /**
   * Return the cached accessible by the given DOM node if it's in subtree of
   * this document accessible or the document accessible itself, otherwise null.
   *
   * @return the accessible object
   */
  LocalAccessible* GetAccessible(nsINode* aNode) const;

  /**
   * Return an accessible for the given node even if the node is not in
   * document's node map cache (like HTML area element).
   *
   * XXX: it should be really merged with GetAccessible().
   */
  LocalAccessible* GetAccessibleEvenIfNotInMap(nsINode* aNode) const;
  LocalAccessible* GetAccessibleEvenIfNotInMapOrContainer(nsINode* aNode) const;

  /**
   * Return whether the given DOM node has an accessible or not.
   */
  bool HasAccessible(nsINode* aNode) const { return GetAccessible(aNode); }

  /**
   * Return the cached accessible by the given unique ID within this document.
   *
   * @note   the unique ID matches with the uniqueID() of Accessible
   *
   * @param  aUniqueID  [in] the unique ID used to cache the node.
   */
  LocalAccessible* GetAccessibleByUniqueID(void* aUniqueID) {
    return UniqueID() == aUniqueID ? this : mAccessibleCache.GetWeak(aUniqueID);
  }

  /**
   * Return the cached accessible by the given unique ID looking through
   * this and nested documents.
   */
  LocalAccessible* GetAccessibleByUniqueIDInSubtree(void* aUniqueID);

  /**
   * Return an accessible for the given DOM node or container accessible if
   * the node is not accessible. If aNoContainerIfPruned is true it will return
   * null if the node is in a pruned subtree (eg. aria-hidden or unselected deck
   * panel)
   */
  LocalAccessible* GetAccessibleOrContainer(
      nsINode* aNode, bool aNoContainerIfPruned = false) const;

  /**
   * Return a container accessible for the given DOM node.
   */
  LocalAccessible* GetContainerAccessible(nsINode* aNode) const;

  /**
   * Return an accessible for the given node if any, or an immediate accessible
   * container for it.
   */
  LocalAccessible* AccessibleOrTrueContainer(
      nsINode* aNode, bool aNoContainerIfPruned = false) const;

  /**
   * Return an accessible for the given node or its first accessible descendant.
   */
  LocalAccessible* GetAccessibleOrDescendant(nsINode* aNode) const;

  /**
   * Returns aria-owns seized child at the given index.
   */
  LocalAccessible* ARIAOwnedAt(LocalAccessible* aParent,
                               uint32_t aIndex) const {
    nsTArray<RefPtr<LocalAccessible>>* children = mARIAOwnsHash.Get(aParent);
    if (children) {
      return children->SafeElementAt(aIndex);
    }
    return nullptr;
  }
  uint32_t ARIAOwnedCount(LocalAccessible* aParent) const {
    nsTArray<RefPtr<LocalAccessible>>* children = mARIAOwnsHash.Get(aParent);
    return children ? children->Length() : 0;
  }

  /**
   * Return true if the given ID is referred by relation attribute.
   */
  bool IsDependentID(dom::Element* aElement, const nsAString& aID) const {
    return GetRelProviders(aElement, aID);
  }

  /**
   * Initialize the newly created accessible and put it into document caches.
   *
   * @param  aAccessible    [in] created accessible
   * @param  aRoleMapEntry  [in] the role map entry role the ARIA role or
   * nullptr if none
   */
  void BindToDocument(LocalAccessible* aAccessible,
                      const nsRoleMapEntry* aRoleMapEntry);

  /**
   * Remove from document and shutdown the given accessible.
   */
  void UnbindFromDocument(LocalAccessible* aAccessible);

  /**
   * Notify the document accessible that content was inserted.
   */
  void ContentInserted(nsIContent* aStartChildNode, nsIContent* aEndChildNode);

  /**
   * @see nsAccessibilityService::ScheduleAccessibilitySubtreeUpdate
   */
  void ScheduleTreeUpdate(nsIContent* aContent);

  /**
   * Update the tree on content removal.
   */
  void ContentRemoved(LocalAccessible* aAccessible);
  void ContentRemoved(nsIContent* aContentNode);

  /**
   * Updates accessible tree when rendered text is changed.
   */
  void UpdateText(nsIContent* aTextNode);

  /**
   * Recreate an accessible, results in hide/show events pair.
   */
  void RecreateAccessible(nsIContent* aContent);

  /**
   * Schedule ARIA owned element relocation if needed. Return true if relocation
   * was scheduled.
   */
  bool RelocateARIAOwnedIfNeeded(nsIContent* aEl);

  /**
   * Return a notification controller associated with the document.
   */
  NotificationController* Controller() const { return mNotificationController; }

  /**
   * If this document is in a content process return the object responsible for
   * communicating with the main process for it.
   */
  DocAccessibleChild* IPCDoc() const { return mIPCDoc; }

  /**
   * Notify the document that a DOM node has been scrolled. document will
   * dispatch throttled accessibility events for scrolling, and a scroll-end
   * event. This function also queues a cache update for ScrollPosition.
   */
  void HandleScroll(nsINode* aTarget);

  /**
   * Retrieves the scroll frame (if it exists) for the given accessible
   * and returns its scroll position and scroll range. If the given
   * accessible is `this`, return the scroll position and range of
   * the root scroll frame. Return values have been scaled by the
   * PresShell's resolution.
   */
  std::pair<nsPoint, nsRect> ComputeScrollData(LocalAccessible* aAcc);

  /**
   * Only works in content process documents.
   */
  bool IsAccessibleBeingMoved(LocalAccessible* aAcc) {
    return mMovedAccessibles.Contains(aAcc);
  }

  void AttrElementWillChange(dom::Element* aElement, nsAtom* aAttr);
  void AttrElementChanged(dom::Element* aElement, nsAtom* aAttr);

 protected:
  virtual ~DocAccessible();

  void LastRelease();

  // DocAccessible
  virtual nsresult AddEventListeners();
  virtual nsresult RemoveEventListeners();

  /**
   * Marks this document as loaded or loading.
   */
  void NotifyOfLoad(uint32_t aLoadEventType);
  void NotifyOfLoading(bool aIsReloading);

  friend class DocManager;

  /**
   * Perform initial update (create accessible tree).
   * Can be overridden by wrappers to prepare initialization work.
   */
  virtual void DoInitialUpdate();

  /**
   * Updates root element and picks up ARIA role on it if any.
   */
  void UpdateRootElIfNeeded();

  /**
   * Process document load notification, fire document load and state busy
   * events if applicable.
   */
  void ProcessLoad();

  /**
   * Append the given document accessible to this document's child document
   * accessibles.
   */
  bool AppendChildDocument(DocAccessible* aChildDocument) {
    // XXX(Bug 1631371) Check if this should use a fallible operation as it
    // pretended earlier, or change the return type to void.
    mChildDocuments.AppendElement(aChildDocument);
    return true;
  }

  /**
   * Remove the given document accessible from this document's child document
   * accessibles.
   */
  void RemoveChildDocument(DocAccessible* aChildDocument) {
    mChildDocuments.RemoveElement(aChildDocument);
  }

  /**
   * Add dependent IDs pointed by accessible element by relation attribute to
   * cache. If the relation attribute is missed then all relation attributes
   * are checked.
   *
   * @param aRelProvider [in] accessible that element has relation attribute
   * @param aRelAttr     [in, optional] relation attribute
   */
  void AddDependentIDsFor(LocalAccessible* aRelProvider,
                          nsAtom* aRelAttr = nullptr);

  /**
   * Remove dependent IDs pointed by accessible element by relation attribute
   * from cache. If the relation attribute is absent then all relation
   * attributes are checked.
   *
   * @param aRelProvider [in] accessible that element has relation attribute
   * @param aRelAttr     [in, optional] relation attribute
   */
  void RemoveDependentIDsFor(LocalAccessible* aRelProvider,
                             nsAtom* aRelAttr = nullptr);

  /**
   * Add dependent elements targeted by a relation attribute on an accessible
   * element to the dependent elements cache. This is used for reflected IDL
   * attributes which return DOM elements and reflect a content attribute, where
   * the IDL attribute has been set to an element. For example, if the
   * .popoverTargetElement IDL attribute is set to an element using JS, the
   * target element will be added to the dependent elements cache. If the
   * relation attribute is not specified, then all relation attributes are
   * checked.
   *
   * @param aRelProvider [in] the accessible with the relation IDL attribute.
   * @param aRelAttr [in, optional] the name of the reflected content attribute.
   *   For example, for the popoverTargetElement IDL attribute, this would be
   * "popovertarget".
   */
  void AddDependentElementsFor(LocalAccessible* aRelProvider,
                               nsAtom* aRelAttr = nullptr);

  /**
   * Remove dependent elements targeted by a relation attribute on an accessible
   * element from the dependent elements cache. If the relation attribute is
   * not specified, then all relation attributes are checked.
   *
   * @param aRelProvider [in] the accessible with the relation IDL attribute.
   * @param aRelAttr [in, optional] the name of the reflected content attribute.
   */
  void RemoveDependentElementsFor(LocalAccessible* aRelProvider,
                                  nsAtom* aRelAttr = nullptr);

  /**
   * Update or recreate an accessible depending on a changed attribute.
   *
   * @param aElement   [in] the element the attribute was changed on
   * @param aAttribute [in] the changed attribute
   * @return            true if an action was taken on the attribute change
   */
  bool UpdateAccessibleOnAttrChange(mozilla::dom::Element* aElement,
                                    nsAtom* aAttribute);

  /**
   * Process ARIA active-descendant attribute change.
   */
  void ARIAActiveDescendantChanged(LocalAccessible* aAccessible);

  /**
   * Update the accessible tree for inserted content.
   */
  void ProcessContentInserted(
      LocalAccessible* aContainer,
      const nsTArray<nsCOMPtr<nsIContent>>* aInsertedContent);
  void ProcessContentInserted(LocalAccessible* aContainer,
                              nsIContent* aInsertedContent);

  /**
   * Used to notify the document to make it process the invalidation list.
   *
   * While children are cached we may encounter the case there's no accessible
   * for referred content by related accessible. Store these related nodes to
   * invalidate their containers later.
   */
  void ProcessInvalidationList();

  /**
   * Process mPendingUpdates
   */
  void ProcessPendingUpdates();

  /**
   * Called from NotificationController to process this doc's
   * queued cache updates. For each acc in the map, this function
   * sends a cache update with its corresponding CacheDomain.
   */
  void ProcessQueuedCacheUpdates();

  /**
   * Called from NotificationController before mutation events are processed to
   * notify the parent process which Accessibles are being moved (if any).
   */
  void SendAccessiblesWillMove();

  /**
   * Called from NotificationController after all mutation events have been
   * processed to clear our data about mutations during this tick.
   */
  void ClearMutationData() {
    mMovedAccessibles.Clear();
    mInsertedAccessibles.Clear();
    mRemovedNodes.Clear();
  }

  /**
   * Steals or puts back accessible subtrees.
   */
  void DoARIAOwnsRelocation(LocalAccessible* aOwner);

  /**
   * Moves children back under their original parents.
   */
  void PutChildrenBack(nsTArray<RefPtr<LocalAccessible>>* aChildren,
                       uint32_t aStartIdx);

  bool MoveChild(LocalAccessible* aChild, LocalAccessible* aNewParent,
                 int32_t aIdxInParent);

  /**
   * Create accessible tree.
   *
   * @param aRoot       [in] a root of subtree to create
   * @param aFocusedAcc [in, optional] a focused accessible under created
   *                      subtree if any
   */
  void CacheChildrenInSubtree(LocalAccessible* aRoot,
                              LocalAccessible** aFocusedAcc = nullptr);
  void CreateSubtree(LocalAccessible* aRoot);

  /**
   * Remove accessibles in subtree from node to accessible map.
   */
  void UncacheChildrenInSubtree(LocalAccessible* aRoot);

  /**
   * Shutdown any cached accessible in the subtree.
   *
   * @param aAccessible  [in] the root of the subrtee to invalidate accessible
   *                      child/parent refs in
   */
  void ShutdownChildrenInSubtree(LocalAccessible* aAccessible);

  /**
   * Return true if the document is a target of document loading events
   * (for example, state busy change or document reload events).
   *
   * Rules: The root chrome document accessible is never an event target
   * (for example, Firefox UI window). If the sub document is loaded within its
   * parent document then the parent document is a target only (aka events
   * coalescence).
   */
  bool IsLoadEventTarget() const;

  /*
   * Set the object responsible for communicating with the main process on
   * behalf of this document.
   */
  void SetIPCDoc(DocAccessibleChild* aIPCDoc);

  friend class DocAccessibleChild;

  /**
   * Used to fire scrolling end event after page scroll.
   *
   * @param aTimer    [in] the timer object
   * @param aClosure  [in] the document accessible where scrolling happens
   */
  static void ScrollTimerCallback(nsITimer* aTimer, void* aClosure);

  void DispatchScrollingEvent(nsINode* aTarget, uint32_t aEventType);

  /**
   * Check if an id attribute change affects aria-activedescendant and handle
   * the aria-activedescendant change if appropriate.
   * If the currently focused element has aria-activedescendant and an
   * element's id changes to match this, the id was probably moved from the
   * previous active descendant, thus making this element the new active
   * descendant. In that case, accessible focus must be changed accordingly.
   */
  void ARIAActiveDescendantIDMaybeMoved(LocalAccessible* aAccessible);

  /**
   * Traverse content subtree and for each node do one of 3 things:
   * 1. Check if content node has an accessible that should be removed and
   *    remove it.
   * 2. Check if content node has an accessible that needs to be recreated.
   *    Remove it and schedule it for reinsertion.
   * 3. Check if content node has no accessible but needs one. Schedule one for
   *    insertion.
   *
   * Returns true if the root node should be reinserted.
   */
  bool PruneOrInsertSubtree(nsIContent* aRoot);

 protected:
  /**
   * State and property flags, kept by mDocFlags.
   */
  enum {
    // Whether the document is a top level content document in this process.
    eTopLevelContentDocInProcess = 1 << 0
  };

  /**
   * Cache of accessibles within this document accessible.
   */
  AccessibleHashtable mAccessibleCache;
  nsTHashMap<nsPtrHashKey<const nsINode>, LocalAccessible*>
      mNodeToAccessibleMap;

  Document* mDocumentNode;
  nsCOMPtr<nsITimer> mScrollWatchTimer;
  nsTHashMap<nsPtrHashKey<nsINode>, TimeStamp> mLastScrollingDispatch;

  /**
   * Bit mask of document load states (@see LoadState).
   */
  uint32_t mLoadState : 3;

  /**
   * Bit mask of other states and props.
   */
  uint32_t mDocFlags : 27;

  /**
   * Tracks whether we have seen changes to this document's content that
   * indicate we should re-send the viewport cache we use for hittesting.
   * This value is set in `BundleFieldsForCache` and processed in
   * `ProcessQueuedCacheUpdates`.
   */
  bool mViewportCacheDirty : 1;

  /**
   * Type of document load event fired after the document is loaded completely.
   */
  uint32_t mLoadEventType;

  /**
   * Reference to anchor jump element.
   */
  nsCOMPtr<nsIContent> mAnchorJumpElm;

  /**
   * A generic state (see items below) before the attribute value was changed.
   * @see AttributeWillChange and AttributeChanged notifications.
   */

  // Previous state bits before attribute change
  uint64_t mPrevStateBits;

  nsTArray<RefPtr<DocAccessible>> mChildDocuments;

  /**
   * A storage class for pairing content with one of its relation attributes.
   */
  class AttrRelProvider {
   public:
    AttrRelProvider(nsAtom* aRelAttr, nsIContent* aContent)
        : mRelAttr(aRelAttr), mContent(aContent) {}

    nsAtom* mRelAttr;
    nsCOMPtr<nsIContent> mContent;

   private:
    AttrRelProvider();
    AttrRelProvider(const AttrRelProvider&);
    AttrRelProvider& operator=(const AttrRelProvider&);
  };

  typedef nsTArray<mozilla::UniquePtr<AttrRelProvider>> AttrRelProviders;
  typedef nsClassHashtable<nsStringHashKey, AttrRelProviders>
      DependentIDsHashtable;

  /**
   * Returns/creates/removes attribute relation providers associated with
   * a DOM document if the element is in uncomposed document or associated
   * with shadow DOM the element is in.
   */
  AttrRelProviders* GetRelProviders(dom::Element* aElement,
                                    const nsAString& aID) const;
  AttrRelProviders* GetOrCreateRelProviders(dom::Element* aElement,
                                            const nsAString& aID);
  void RemoveRelProvidersIfEmpty(dom::Element* aElement, const nsAString& aID);

  /**
   * A map used to look up the target node for an implicit reverse relation
   * where the target of the explicit relation is specified as an id.
   * For example:
   * <div id="label">Name:</div><input aria-labelledby="label">
   * The div should get a LABEL_FOR relation targeting the input. To facilitate
   * that, mDependentIDsHashes maps from "label" to an AttrRelProvider
   * specifying aria-labelledby and the input. Because ids are scoped to the
   * nearest ancestor document or shadow root, mDependentIDsHashes maps from the
   * DocumentOrShadowRoot first.
   */
  nsClassHashtable<nsPtrHashKey<dom::DocumentOrShadowRoot>,
                   DependentIDsHashtable>
      mDependentIDsHashes;

  /**
   * A map used to look up the target element for an implicit reverse relation
   * where the target of the explicit relation is also specified as an element.
   * This is similar to mDependentIDsHashes, except that this is used when a
   * DOM property is used to set the relation target element directly, rather
   * than using an id. For example:
   * <button>More info</button><div popover>Some info</div>
   * The button's .popoverTargetElement property is set to the div so that the
   * button invokes the popover.
   * To facilitate finding the invoker given the popover, mDependentElementsMap
   * maps from the div to an AttrRelProvider specifying popovertarget and the
   * button.
   */
  nsTHashMap<nsIContent*, AttrRelProviders> mDependentElementsMap;

  friend class RelatedAccIterator;

  /**
   * Used for our caching algorithm. We store the list of nodes that should be
   * invalidated.
   *
   * @see ProcessInvalidationList
   */
  nsTArray<RefPtr<nsIContent>> mInvalidationList;

  /**
   * Holds a list of aria-owns relocations.
   */
  nsClassHashtable<nsPtrHashKey<LocalAccessible>,
                   nsTArray<RefPtr<LocalAccessible>>>
      mARIAOwnsHash;

  /**
   * Keeps a list of pending subtrees to update post-refresh.
   */
  nsTArray<RefPtr<nsIContent>> mPendingUpdates;

  /**
   * Used to process notification from core and accessible events.
   */
  RefPtr<NotificationController> mNotificationController;
  friend class EventTree;
  friend class NotificationController;

 private:
  void SetRoleMapEntryForDoc(dom::Element* aElement);

  /**
   * This must be called whenever an Accessible is moved in a content process.
   * It keeps track of Accessibles moved during this tick.
   */
  void TrackMovedAccessible(LocalAccessible* aAcc);

  /**
   * For hidden subtrees, fire a name/description change event if the subtree
   * is a target of aria-labelledby/describedby.
   * This does nothing if it is called on a node which is not part of a hidden
   * aria-labelledby/describedby target.
   */
  void MaybeHandleChangeToHiddenNameOrDescription(nsIContent* aChild);

  void MaybeFireEventsForChangedPopover(LocalAccessible* aAcc);

  PresShell* mPresShell;

  // Exclusively owned by IPDL so don't manually delete it!
  // Cleared in ActorDestroy
  DocAccessibleChild* mIPCDoc;

  // These data structures map between LocalAccessibles and CacheDomains,
  // tracking cache updates that have been queued during the current tick but
  // not yet sent. If there are a lot of nearby text cache updates (e.g. during
  // a reflow), it is much more performant to process them in order because we
  // then benefit from the layout line cursor. However, we still only want to
  // process each LocalAccessible only once. Therefore, we use an array for
  // ordering and a hash map to avoid duplicates, since Gecko has no ordered
  // set data structure. The array contains pairs of LocalAccessible and cache
  // domain. The hash map maps from LocalAccessible to the corresponding index
  // in the array. These data structures must be kept in sync. It is possible
  // for these to contain a reference to the document they live on. We clear
  // them in Shutdown() to avoid cyclical references.
  nsTArray<std::pair<RefPtr<LocalAccessible>, uint64_t>>
      mQueuedCacheUpdatesArray;
  nsTHashMap<LocalAccessible*, size_t> mQueuedCacheUpdatesHash;

  // A set of Accessibles moved during this tick. Only used in content
  // processes.
  nsTHashSet<RefPtr<LocalAccessible>> mMovedAccessibles;
  // A set of Accessibles inserted during this tick. Only used in content
  // processes. This is needed to prevent insertions + moves of the same
  // Accessible in the same tick from being tracked as moves.
  nsTHashSet<RefPtr<LocalAccessible>> mInsertedAccessibles;
  // A set of DOM nodes removed during this tick. This avoids a lot of pointless
  // recursive DOM traversals.
  nsTHashSet<nsIContent*> mRemovedNodes;
};

inline DocAccessible* LocalAccessible::AsDoc() {
  return IsDoc() ? static_cast<DocAccessible*>(this) : nullptr;
}

}  // namespace a11y
}  // namespace mozilla

#endif