dom/base/nsDOMMutationObserver.cpp
author Csoregi Natalia <ncsoregi@mozilla.com>
Thu, 01 Mar 2018 16:29:02 +0200
changeset 458530 a416b0a21b1395dfe7dc28577a31be57c075d9b4
parent 458470 55c94c05c57f0bb34ca131c68c79e05a97aa4b6c
child 458621 e3d9710edbd780ce29c8635db6d8bd63f22fff3c
permissions -rw-r--r--
Backed out 7 changesets (bug 1193394) for browser-chrome failures on browser_ext_popup_background.js. CLOSED TREE Backed out changeset 9683f24ff8ec (bug 1193394) Backed out changeset 0e7140a7c841 (bug 1193394) Backed out changeset a0e26f6b2784 (bug 1193394) Backed out changeset 29e1fceaf48d (bug 1193394) Backed out changeset b8632bbbd273 (bug 1193394) Backed out changeset a54ef2d8f896 (bug 1193394) Backed out changeset 55c94c05c57f (bug 1193394)

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */

#include "nsDOMMutationObserver.h"

#include "mozilla/AnimationTarget.h"
#include "mozilla/Maybe.h"
#include "mozilla/OwningNonNull.h"

#include "mozilla/dom/Animation.h"
#include "mozilla/dom/KeyframeEffectReadOnly.h"
#include "mozilla/dom/DocGroup.h"

#include "nsContentUtils.h"
#include "nsCSSPseudoElements.h"
#include "nsError.h"
#include "nsIScriptGlobalObject.h"
#include "nsServiceManagerUtils.h"
#include "nsTextFragment.h"
#include "nsThreadUtils.h"

using namespace mozilla;

using mozilla::dom::TreeOrderComparator;
using mozilla::dom::Animation;
using mozilla::dom::Element;

AutoTArray<RefPtr<nsDOMMutationObserver>, 4>*
  nsDOMMutationObserver::sScheduledMutationObservers = nullptr;

uint32_t nsDOMMutationObserver::sMutationLevel = 0;
uint64_t nsDOMMutationObserver::sCount = 0;

AutoTArray<AutoTArray<RefPtr<nsDOMMutationObserver>, 4>, 4>*
nsDOMMutationObserver::sCurrentlyHandlingObservers = nullptr;

nsINodeList*
nsDOMMutationRecord::AddedNodes()
{
  if (!mAddedNodes) {
    mAddedNodes = new nsSimpleContentList(mTarget);
  }
  return mAddedNodes;
}

nsINodeList*
nsDOMMutationRecord::RemovedNodes()
{
  if (!mRemovedNodes) {
    mRemovedNodes = new nsSimpleContentList(mTarget);
  }
  return mRemovedNodes;
}

NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsDOMMutationRecord)
  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
  NS_INTERFACE_MAP_ENTRY(nsISupports)
NS_INTERFACE_MAP_END

NS_IMPL_CYCLE_COLLECTING_ADDREF(nsDOMMutationRecord)
NS_IMPL_CYCLE_COLLECTING_RELEASE(nsDOMMutationRecord)

NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(nsDOMMutationRecord,
                                      mTarget,
                                      mPreviousSibling, mNextSibling,
                                      mAddedNodes, mRemovedNodes,
                                      mAddedAnimations, mRemovedAnimations,
                                      mChangedAnimations,
                                      mNext, mOwner)

// Observer

bool
nsMutationReceiverBase::IsObservable(nsIContent* aContent)
{
  return !aContent->ChromeOnlyAccess() &&
    (Observer()->IsChrome() || !aContent->IsInAnonymousSubtree());
}

NS_IMPL_ADDREF(nsMutationReceiver)
NS_IMPL_RELEASE(nsMutationReceiver)

NS_INTERFACE_MAP_BEGIN(nsMutationReceiver)
  NS_INTERFACE_MAP_ENTRY(nsISupports)
  NS_INTERFACE_MAP_ENTRY(nsIMutationObserver)
NS_INTERFACE_MAP_END

nsMutationReceiver::nsMutationReceiver(nsINode* aTarget,
                                       nsDOMMutationObserver* aObserver)
: nsMutationReceiverBase(aTarget, aObserver)
{
  mTarget->BindObject(aObserver);
}

void
nsMutationReceiver::Disconnect(bool aRemoveFromObserver)
{
  if (mRegisterTarget) {
    mRegisterTarget->RemoveMutationObserver(this);
    mRegisterTarget = nullptr;
  }

  mParent = nullptr;
  nsINode* target = mTarget;
  mTarget = nullptr;
  nsDOMMutationObserver* observer = mObserver;
  mObserver = nullptr;
  RemoveClones();

  if (target && observer) {
    if (aRemoveFromObserver) {
      static_cast<nsDOMMutationObserver*>(observer)->RemoveReceiver(this);
    }
    // UnbindObject may delete 'this'!
    target->UnbindObject(observer);
  }
}

void
nsMutationReceiver::NativeAnonymousChildListChange(nsIDocument* aDocument,
                                                   nsIContent* aContent,
                                                   bool aIsRemove) {
  if (!NativeAnonymousChildList()) {
    return;
  }

  nsINode* parent = aContent->GetParentNode();
  if (!parent ||
      (!Subtree() && Target() != parent) ||
      (Subtree() && RegisterTarget()->SubtreeRoot() != parent->SubtreeRoot())) {
    return;
  }

  nsDOMMutationRecord* m =
    Observer()->CurrentRecord(nsGkAtoms::nativeAnonymousChildList);

  if (m->mTarget) {
    return;
  }
  m->mTarget = parent;

  if (aIsRemove) {
    m->mRemovedNodes = new nsSimpleContentList(parent);
    m->mRemovedNodes->AppendElement(aContent);
  } else {
    m->mAddedNodes = new nsSimpleContentList(parent);
    m->mAddedNodes->AppendElement(aContent);
  }
}

void
nsMutationReceiver::AttributeWillChange(nsIDocument* aDocument,
                                        mozilla::dom::Element* aElement,
                                        int32_t aNameSpaceID,
                                        nsAtom* aAttribute,
                                        int32_t aModType,
                                        const nsAttrValue* aNewValue)
{
  if (nsAutoMutationBatch::IsBatching() ||
      !ObservesAttr(RegisterTarget(), aElement, aNameSpaceID, aAttribute)) {
    return;
  }

  nsDOMMutationRecord* m =
    Observer()->CurrentRecord(nsGkAtoms::attributes);

  NS_ASSERTION(!m->mTarget || m->mTarget == aElement,
               "Wrong target!");
  NS_ASSERTION(!m->mAttrName || m->mAttrName == aAttribute,
               "Wrong attribute!");
  if (!m->mTarget) {
    m->mTarget = aElement;
    m->mAttrName = aAttribute;
    if (aNameSpaceID == kNameSpaceID_None) {
      m->mAttrNamespace.SetIsVoid(true);
    } else {
      nsContentUtils::NameSpaceManager()->GetNameSpaceURI(aNameSpaceID,
                                                          m->mAttrNamespace);
    }
  }

  if (AttributeOldValue() && m->mPrevValue.IsVoid()) {
    if (!aElement->GetAttr(aNameSpaceID, aAttribute, m->mPrevValue)) {
      m->mPrevValue.SetIsVoid(true);
    }
  }
}

void
nsMutationReceiver::CharacterDataWillChange(nsIDocument* aDocument,
                                            nsIContent* aContent,
                                            const CharacterDataChangeInfo&)
{
  if (nsAutoMutationBatch::IsBatching() ||
      !CharacterData() ||
      (!Subtree() && aContent != Target()) ||
      (Subtree() && RegisterTarget()->SubtreeRoot() != aContent->SubtreeRoot()) ||
      !IsObservable(aContent)) {
    return;
  }

  nsDOMMutationRecord* m =
    Observer()->CurrentRecord(nsGkAtoms::characterData);

  NS_ASSERTION(!m->mTarget || m->mTarget == aContent,
               "Wrong target!");

  if (!m->mTarget) {
    m->mTarget = aContent;
  }
  if (CharacterDataOldValue() && m->mPrevValue.IsVoid()) {
    aContent->GetText()->AppendTo(m->mPrevValue);
  }
}

void
nsMutationReceiver::ContentAppended(nsIDocument* aDocument,
                                    nsIContent* aContainer,
                                    nsIContent* aFirstNewContent)
{
  nsINode* parent = NODE_FROM(aContainer, aDocument);
  bool wantsChildList =
    ChildList() &&
    ((Subtree() && RegisterTarget()->SubtreeRoot() == parent->SubtreeRoot()) ||
     parent == Target());
  if (!wantsChildList || !IsObservable(aFirstNewContent)) {
    return;
  }

  if (nsAutoMutationBatch::IsBatching()) {
    if (parent == nsAutoMutationBatch::GetBatchTarget()) {
      nsAutoMutationBatch::UpdateObserver(Observer(), wantsChildList);
    }
    return;
  }

  nsDOMMutationRecord* m =
    Observer()->CurrentRecord(nsGkAtoms::childList);
  NS_ASSERTION(!m->mTarget || m->mTarget == parent,
               "Wrong target!");
  if (m->mTarget) {
    // Already handled case.
    return;
  }
  m->mTarget = parent;
  m->mAddedNodes = new nsSimpleContentList(parent);

  nsINode* n = aFirstNewContent;
  while (n) {
    m->mAddedNodes->AppendElement(static_cast<nsIContent*>(n));
    n = n->GetNextSibling();
  }
  m->mPreviousSibling = aFirstNewContent->GetPreviousSibling();
}

void
nsMutationReceiver::ContentInserted(nsIDocument* aDocument,
                                    nsIContent* aContainer,
                                    nsIContent* aChild)
{
  nsINode* parent = NODE_FROM(aContainer, aDocument);
  bool wantsChildList =
    ChildList() &&
    ((Subtree() && RegisterTarget()->SubtreeRoot() == parent->SubtreeRoot()) ||
     parent == Target());
  if (!wantsChildList || !IsObservable(aChild)) {
    return;
  }

  if (nsAutoMutationBatch::IsBatching()) {
    if (parent == nsAutoMutationBatch::GetBatchTarget()) {
      nsAutoMutationBatch::UpdateObserver(Observer(), wantsChildList);
    }
    return;
  }

  nsDOMMutationRecord* m =
    Observer()->CurrentRecord(nsGkAtoms::childList);
  if (m->mTarget) {
    // Already handled case.
    return;
  }
  m->mTarget = parent;
  m->mAddedNodes = new nsSimpleContentList(parent);
  m->mAddedNodes->AppendElement(aChild);
  m->mPreviousSibling = aChild->GetPreviousSibling();
  m->mNextSibling = aChild->GetNextSibling();
}

void
nsMutationReceiver::ContentRemoved(nsIDocument* aDocument,
                                   nsIContent* aContainer,
                                   nsIContent* aChild,
                                   nsIContent* aPreviousSibling)
{
  if (!IsObservable(aChild)) {
    return;
  }

  nsINode* parent = NODE_FROM(aContainer, aDocument);
  if (Subtree() && parent->SubtreeRoot() != RegisterTarget()->SubtreeRoot()) {
    return;
  }
  if (nsAutoMutationBatch::IsBatching()) {
    if (nsAutoMutationBatch::IsRemovalDone()) {
      // This can happen for example if HTML parser parses to
      // context node, but needs to move elements around.
      return;
    }
    if (nsAutoMutationBatch::GetBatchTarget() != parent) {
      return;
    }

    bool wantsChildList = ChildList() && (Subtree() || parent == Target());
    if (wantsChildList || Subtree()) {
      nsAutoMutationBatch::NodeRemoved(aChild);
      nsAutoMutationBatch::UpdateObserver(Observer(), wantsChildList);
    }

    return;
  }

  if (Subtree()) {
    // Try to avoid creating transient observer if the node
    // already has an observer observing the same set of nodes.
    nsMutationReceiver* orig = GetParent() ? GetParent() : this;
    if (Observer()->GetReceiverFor(aChild, false, false) != orig) {
      bool transientExists = false;
      bool isNewEntry = false;
      nsCOMArray<nsMutationReceiver>* transientReceivers =
        Observer()->mTransientReceivers.LookupForAdd(aChild).OrInsert(
          [&isNewEntry] () {
            isNewEntry = true;
            return new nsCOMArray<nsMutationReceiver>();
          });
      if (!isNewEntry) {
        for (int32_t i = 0; i < transientReceivers->Count(); ++i) {
          nsMutationReceiver* r = transientReceivers->ObjectAt(i);
          if (r->GetParent() == orig) {
            transientExists = true;
          }
        }
      }
      if (!transientExists) {
        // Make sure the elements which are removed from the
        // subtree are kept in the same observation set.
        nsMutationReceiver* tr;
        if (orig->Animations()) {
          tr = nsAnimationReceiver::Create(aChild, orig);
        } else {
          tr = nsMutationReceiver::Create(aChild, orig);
        }
        transientReceivers->AppendObject(tr);
      }
    }
  }

  if (ChildList() && (Subtree() || parent == Target())) {
    nsDOMMutationRecord* m =
      Observer()->CurrentRecord(nsGkAtoms::childList);
    if (m->mTarget) {
      // Already handled case.
      return;
    }
    MOZ_ASSERT(parent);

    m->mTarget = parent;
    m->mRemovedNodes = new nsSimpleContentList(parent);
    m->mRemovedNodes->AppendElement(aChild);
    m->mPreviousSibling = aPreviousSibling;
    m->mNextSibling = aPreviousSibling ?
      aPreviousSibling->GetNextSibling() : parent->GetFirstChild();
  }
  // We need to schedule always, so that after microtask mTransientReceivers
  // can be cleared correctly.
  Observer()->ScheduleForRun();
}

void nsMutationReceiver::NodeWillBeDestroyed(const nsINode *aNode)
{
  NS_ASSERTION(!mParent, "Shouldn't have mParent here!");
  Disconnect(true);
}

void
nsAnimationReceiver::RecordAnimationMutation(Animation* aAnimation,
                                             AnimationMutation aMutationType)
{
  mozilla::dom::AnimationEffectReadOnly* effect = aAnimation->GetEffect();
  if (!effect) {
    return;
  }

  mozilla::dom::KeyframeEffectReadOnly* keyframeEffect =
    effect->AsKeyframeEffect();
  if (!keyframeEffect) {
    return;
  }

  Maybe<NonOwningAnimationTarget> animationTarget = keyframeEffect->GetTarget();
  if (!animationTarget) {
    return;
  }

  Element* elem = animationTarget->mElement;
  if (!Animations() || !(Subtree() || elem == Target()) ||
      elem->ChromeOnlyAccess()) {
    return;
  }

  // Record animations targeting to a pseudo element only when subtree is true.
  if (animationTarget->mPseudoType != mozilla::CSSPseudoElementType::NotPseudo &&
      !Subtree()) {
    return;
  }

  if (nsAutoAnimationMutationBatch::IsBatching()) {
    switch (aMutationType) {
      case eAnimationMutation_Added:
        nsAutoAnimationMutationBatch::AnimationAdded(aAnimation, elem);
        break;
      case eAnimationMutation_Changed:
        nsAutoAnimationMutationBatch::AnimationChanged(aAnimation, elem);
        break;
      case eAnimationMutation_Removed:
        nsAutoAnimationMutationBatch::AnimationRemoved(aAnimation, elem);
        break;
    }

    nsAutoAnimationMutationBatch::AddObserver(Observer());
    return;
  }

  nsDOMMutationRecord* m =
    Observer()->CurrentRecord(nsGkAtoms::animations);

  NS_ASSERTION(!m->mTarget, "Wrong target!");

  m->mTarget = elem;

  switch (aMutationType) {
    case eAnimationMutation_Added:
      m->mAddedAnimations.AppendElement(aAnimation);
      break;
    case eAnimationMutation_Changed:
      m->mChangedAnimations.AppendElement(aAnimation);
      break;
    case eAnimationMutation_Removed:
      m->mRemovedAnimations.AppendElement(aAnimation);
      break;
  }
}

void
nsAnimationReceiver::AnimationAdded(Animation* aAnimation)
{
  RecordAnimationMutation(aAnimation, eAnimationMutation_Added);
}

void
nsAnimationReceiver::AnimationChanged(Animation* aAnimation)
{
  RecordAnimationMutation(aAnimation, eAnimationMutation_Changed);
}

void
nsAnimationReceiver::AnimationRemoved(Animation* aAnimation)
{
  RecordAnimationMutation(aAnimation, eAnimationMutation_Removed);
}

NS_IMPL_ISUPPORTS_INHERITED(nsAnimationReceiver, nsMutationReceiver,
                            nsIAnimationObserver)

// Observer

NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsDOMMutationObserver)
  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
  NS_INTERFACE_MAP_ENTRY(nsISupports)
  NS_INTERFACE_MAP_ENTRY(nsDOMMutationObserver)
NS_INTERFACE_MAP_END

NS_IMPL_CYCLE_COLLECTING_ADDREF(nsDOMMutationObserver)
NS_IMPL_CYCLE_COLLECTING_RELEASE(nsDOMMutationObserver)

NS_IMPL_CYCLE_COLLECTION_CLASS(nsDOMMutationObserver)

NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(nsDOMMutationObserver)
  NS_IMPL_CYCLE_COLLECTION_TRACE_PRESERVED_WRAPPER
NS_IMPL_CYCLE_COLLECTION_TRACE_END

NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsDOMMutationObserver)
  NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER
  NS_IMPL_CYCLE_COLLECTION_UNLINK(mOwner)
  for (int32_t i = 0; i < tmp->mReceivers.Count(); ++i) {
    tmp->mReceivers[i]->Disconnect(false);
  }
  tmp->mReceivers.Clear();
  tmp->ClearPendingRecords();
  NS_IMPL_CYCLE_COLLECTION_UNLINK(mCallback)
  // No need to handle mTransientReceivers
  NS_IMPL_CYCLE_COLLECTION_UNLINK_END

NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsDOMMutationObserver)
  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mOwner)
  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mReceivers)
  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mFirstPendingMutation)
  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mCallback)
  // No need to handle mTransientReceivers
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END

nsMutationReceiver*
nsDOMMutationObserver::GetReceiverFor(nsINode* aNode, bool aMayCreate,
                                      bool aWantsAnimations)
{
  MOZ_ASSERT(aMayCreate || !aWantsAnimations,
             "the value of aWantsAnimations doesn't matter when aMayCreate is "
             "false, so just pass in false for it");

  if (!aMayCreate && !aNode->MayHaveDOMMutationObserver()) {
    return nullptr;
  }

  for (int32_t i = 0; i < mReceivers.Count(); ++i) {
    if (mReceivers[i]->Target() == aNode) {
      return mReceivers[i];
    }
  }
  if (!aMayCreate) {
    return nullptr;
  }

  nsMutationReceiver* r;
  if (aWantsAnimations) {
    r = nsAnimationReceiver::Create(aNode, this);
  } else {
    r = nsMutationReceiver::Create(aNode, this);
  }
  mReceivers.AppendObject(r);
  return r;
}

void
nsDOMMutationObserver::RemoveReceiver(nsMutationReceiver* aReceiver)
{
  mReceivers.RemoveObject(aReceiver);
}

void
nsDOMMutationObserver::GetAllSubtreeObserversFor(nsINode* aNode,
                                                 nsTArray<nsMutationReceiver*>&
                                                   aReceivers)
{
  nsINode* n = aNode;
  while (n) {
    if (n->MayHaveDOMMutationObserver()) {
      nsMutationReceiver* r = GetReceiverFor(n, false, false);
      if (r && r->Subtree() && !aReceivers.Contains(r)) {
        aReceivers.AppendElement(r);
        // If we've found all the receivers the observer has,
        // no need to search for more.
        if (mReceivers.Count() == int32_t(aReceivers.Length())) {
          return;
        }
      }
      nsCOMArray<nsMutationReceiver>* transientReceivers = nullptr;
      if (mTransientReceivers.Get(n, &transientReceivers) && transientReceivers) {
        for (int32_t i = 0; i < transientReceivers->Count(); ++i) {
          nsMutationReceiver* r = transientReceivers->ObjectAt(i);
          nsMutationReceiver* parent = r->GetParent();
          if (r->Subtree() && parent && !aReceivers.Contains(parent)) {
            aReceivers.AppendElement(parent);
          }
        }
        if (mReceivers.Count() == int32_t(aReceivers.Length())) {
          return;
        }
      }
    }
    n = n->GetParentNode();
  }
}

void
nsDOMMutationObserver::ScheduleForRun()
{
  nsDOMMutationObserver::AddCurrentlyHandlingObserver(this, sMutationLevel);

  if (mWaitingForRun) {
    return;
  }
  mWaitingForRun = true;
  RescheduleForRun();
}

class MutationObserverMicroTask final : public MicroTaskRunnable
{
public:
  virtual void Run(AutoSlowOperation& aAso) override
  {
    nsDOMMutationObserver::HandleMutations(aAso);
  }

  virtual bool Suppressed() override
  {
    return nsDOMMutationObserver::AllScheduledMutationObserversAreSuppressed();
  }
};

/* static */ void
nsDOMMutationObserver::QueueMutationObserverMicroTask()
{
  CycleCollectedJSContext* ccjs = CycleCollectedJSContext::Get();
  if (!ccjs) {
    return;
  }

  RefPtr<MutationObserverMicroTask> momt =
    new MutationObserverMicroTask();
  ccjs->DispatchMicroTaskRunnable(momt.forget());
}

void
nsDOMMutationObserver::HandleMutations(mozilla::AutoSlowOperation& aAso)
{
  if (sScheduledMutationObservers ||
      mozilla::dom::DocGroup::sPendingDocGroups) {
    HandleMutationsInternal(aAso);
  }
}

void
nsDOMMutationObserver::RescheduleForRun()
{
  if (!sScheduledMutationObservers) {
    CycleCollectedJSContext* ccjs = CycleCollectedJSContext::Get();
    if (!ccjs) {
      return;
    }

    RefPtr<MutationObserverMicroTask> momt =
      new MutationObserverMicroTask();
    ccjs->DispatchMicroTaskRunnable(momt.forget());
    sScheduledMutationObservers = new AutoTArray<RefPtr<nsDOMMutationObserver>, 4>;
  }

  bool didInsert = false;
  for (uint32_t i = 0; i < sScheduledMutationObservers->Length(); ++i) {
    if (static_cast<nsDOMMutationObserver*>((*sScheduledMutationObservers)[i])
          ->mId > mId) {
      sScheduledMutationObservers->InsertElementAt(i, this);
      didInsert = true;
      break;
    }
  }
  if (!didInsert) {
    sScheduledMutationObservers->AppendElement(this);
  }
}

void
nsDOMMutationObserver::Observe(nsINode& aTarget,
                               const mozilla::dom::MutationObserverInit& aOptions,
                               mozilla::ErrorResult& aRv)
{

  bool childList = aOptions.mChildList;
  bool attributes =
    aOptions.mAttributes.WasPassed() &&
    aOptions.mAttributes.Value();
  bool characterData =
    aOptions.mCharacterData.WasPassed() &&
    aOptions.mCharacterData.Value();
  bool subtree = aOptions.mSubtree;
  bool attributeOldValue =
    aOptions.mAttributeOldValue.WasPassed() &&
    aOptions.mAttributeOldValue.Value();
  bool nativeAnonymousChildList = aOptions.mNativeAnonymousChildList;
  bool characterDataOldValue =
    aOptions.mCharacterDataOldValue.WasPassed() &&
    aOptions.mCharacterDataOldValue.Value();
  bool animations = aOptions.mAnimations;

  if (!aOptions.mAttributes.WasPassed() &&
      (aOptions.mAttributeOldValue.WasPassed() ||
       aOptions.mAttributeFilter.WasPassed())) {
    attributes = true;
  }

  if (!aOptions.mCharacterData.WasPassed() &&
      aOptions.mCharacterDataOldValue.WasPassed()) {
    characterData = true;
  }

  if (!(childList || attributes || characterData || animations ||
        nativeAnonymousChildList)) {
    aRv.Throw(NS_ERROR_DOM_TYPE_ERR);
    return;
  }

  if (aOptions.mAttributeOldValue.WasPassed() &&
      aOptions.mAttributeOldValue.Value() &&
      aOptions.mAttributes.WasPassed() &&
      !aOptions.mAttributes.Value()) {
    aRv.Throw(NS_ERROR_DOM_TYPE_ERR);
    return;
  }

  if (aOptions.mAttributeFilter.WasPassed() &&
      aOptions.mAttributes.WasPassed() &&
      !aOptions.mAttributes.Value()) {
    aRv.Throw(NS_ERROR_DOM_TYPE_ERR);
    return;
  }

  if (aOptions.mCharacterDataOldValue.WasPassed() &&
      aOptions.mCharacterDataOldValue.Value() &&
      aOptions.mCharacterData.WasPassed() &&
      !aOptions.mCharacterData.Value()) {
    aRv.Throw(NS_ERROR_DOM_TYPE_ERR);
    return;
  }

  nsTArray<RefPtr<nsAtom>> filters;
  bool allAttrs = true;
  if (aOptions.mAttributeFilter.WasPassed()) {
    allAttrs = false;
    const mozilla::dom::Sequence<nsString>& filtersAsString =
      aOptions.mAttributeFilter.Value();
    uint32_t len = filtersAsString.Length();
    filters.SetCapacity(len);

    for (uint32_t i = 0; i < len; ++i) {
      filters.AppendElement(NS_Atomize(filtersAsString[i]));
    }
  }

  nsMutationReceiver* r = GetReceiverFor(&aTarget, true, animations);
  r->SetChildList(childList);
  r->SetAttributes(attributes);
  r->SetCharacterData(characterData);
  r->SetSubtree(subtree);
  r->SetAttributeOldValue(attributeOldValue);
  r->SetCharacterDataOldValue(characterDataOldValue);
  r->SetNativeAnonymousChildList(nativeAnonymousChildList);
  r->SetAttributeFilter(Move(filters));
  r->SetAllAttributes(allAttrs);
  r->SetAnimations(animations);
  r->RemoveClones();

#ifdef DEBUG
  for (int32_t i = 0; i < mReceivers.Count(); ++i) {
    NS_WARNING_ASSERTION(mReceivers[i]->Target(),
                         "All the receivers should have a target!");
  }
#endif
}

void
nsDOMMutationObserver::Disconnect()
{
  for (int32_t i = 0; i < mReceivers.Count(); ++i) {
    mReceivers[i]->Disconnect(false);
  }
  mReceivers.Clear();
  mCurrentMutations.Clear();
  ClearPendingRecords();
}

void
nsDOMMutationObserver::TakeRecords(
                         nsTArray<RefPtr<nsDOMMutationRecord> >& aRetVal)
{
  aRetVal.Clear();
  aRetVal.SetCapacity(mPendingMutationCount);
  RefPtr<nsDOMMutationRecord> current;
  current.swap(mFirstPendingMutation);
  for (uint32_t i = 0; i < mPendingMutationCount; ++i) {
    RefPtr<nsDOMMutationRecord> next;
    current->mNext.swap(next);
    if (!mMergeAttributeRecords ||
        !MergeableAttributeRecord(aRetVal.SafeLastElement(nullptr),
                                  current)) {
      *aRetVal.AppendElement() = current.forget();
    }
    current.swap(next);
  }
  ClearPendingRecords();
}

void
nsDOMMutationObserver::GetObservingInfo(
                         nsTArray<Nullable<MutationObservingInfo>>& aResult,
                         mozilla::ErrorResult& aRv)
{
  aResult.SetCapacity(mReceivers.Count());
  for (int32_t i = 0; i < mReceivers.Count(); ++i) {
    MutationObservingInfo& info = aResult.AppendElement()->SetValue();
    nsMutationReceiver* mr = mReceivers[i];
    info.mChildList = mr->ChildList();
    info.mAttributes.Construct(mr->Attributes());
    info.mCharacterData.Construct(mr->CharacterData());
    info.mSubtree = mr->Subtree();
    info.mAttributeOldValue.Construct(mr->AttributeOldValue());
    info.mCharacterDataOldValue.Construct(mr->CharacterDataOldValue());
    info.mNativeAnonymousChildList = mr->NativeAnonymousChildList();
    info.mAnimations = mr->Animations();
    nsTArray<RefPtr<nsAtom>>& filters = mr->AttributeFilter();
    if (filters.Length()) {
      info.mAttributeFilter.Construct();
      mozilla::dom::Sequence<nsString>& filtersAsStrings =
        info.mAttributeFilter.Value();
      nsString* strings = filtersAsStrings.AppendElements(filters.Length(),
                                                          mozilla::fallible);
      if (!strings) {
        aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
        return;
      }
      for (size_t j = 0; j < filters.Length(); ++j) {
        filters[j]->ToString(strings[j]);
      }
    }
    info.mObservedNode = mr->Target();
  }
}

// static
already_AddRefed<nsDOMMutationObserver>
nsDOMMutationObserver::Constructor(const mozilla::dom::GlobalObject& aGlobal,
                                   mozilla::dom::MutationCallback& aCb,
                                   mozilla::ErrorResult& aRv)
{
  nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(aGlobal.GetAsSupports());
  if (!window) {
    aRv.Throw(NS_ERROR_FAILURE);
    return nullptr;
  }
  bool isChrome = nsContentUtils::IsChromeDoc(window->GetExtantDoc());
  RefPtr<nsDOMMutationObserver> observer =
    new nsDOMMutationObserver(window.forget(), aCb, isChrome);
  return observer.forget();
}


bool
nsDOMMutationObserver::MergeableAttributeRecord(nsDOMMutationRecord* aOldRecord,
                                                nsDOMMutationRecord* aRecord)
{
  MOZ_ASSERT(mMergeAttributeRecords);
  return
    aOldRecord &&
    aOldRecord->mType == nsGkAtoms::attributes &&
    aOldRecord->mType == aRecord->mType &&
    aOldRecord->mTarget == aRecord->mTarget &&
    aOldRecord->mAttrName == aRecord->mAttrName &&
    aOldRecord->mAttrNamespace.Equals(aRecord->mAttrNamespace);
}

void
nsDOMMutationObserver::HandleMutation()
{
  NS_ASSERTION(nsContentUtils::IsSafeToRunScript(), "Whaat!");
  NS_ASSERTION(mCurrentMutations.IsEmpty(),
               "Still generating MutationRecords?");

  mWaitingForRun = false;

  for (int32_t i = 0; i < mReceivers.Count(); ++i) {
    mReceivers[i]->RemoveClones();
  }
  mTransientReceivers.Clear();

  nsPIDOMWindowOuter* outer = mOwner->GetOuterWindow();
  if (!mPendingMutationCount || !outer ||
      outer->GetCurrentInnerWindow() != mOwner) {
    ClearPendingRecords();
    return;
  }

  mozilla::dom::Sequence<mozilla::OwningNonNull<nsDOMMutationRecord> >
    mutations;
  if (mutations.SetCapacity(mPendingMutationCount, mozilla::fallible)) {
    // We can't use TakeRecords easily here, because it deals with a
    // different type of array, and we want to optimize out any extra copying.
    RefPtr<nsDOMMutationRecord> current;
    current.swap(mFirstPendingMutation);
    for (uint32_t i = 0; i < mPendingMutationCount; ++i) {
      RefPtr<nsDOMMutationRecord> next;
      current->mNext.swap(next);
      if (!mMergeAttributeRecords ||
          !MergeableAttributeRecord(mutations.Length() ?
                                      mutations.LastElement().get() : nullptr,
                                    current)) {
        *mutations.AppendElement(mozilla::fallible) = current;
      }
      current.swap(next);
    }
  }
  ClearPendingRecords();

  mCallback->Call(this, mutations, *this);
}

void
nsDOMMutationObserver::HandleMutationsInternal(AutoSlowOperation& aAso)
{
  nsTArray<RefPtr<nsDOMMutationObserver> >* suppressedObservers = nullptr;

  // Let signalList be a copy of unit of related similar-origin browsing
  // contexts' signal slot list.
  nsTArray<RefPtr<HTMLSlotElement>> signalList;
  if (DocGroup::sPendingDocGroups) {
    for (uint32_t i = 0; i < DocGroup::sPendingDocGroups->Length(); ++i) {
      DocGroup* docGroup = DocGroup::sPendingDocGroups->ElementAt(i);
      signalList.AppendElements(docGroup->SignalSlotList());

      // Empty unit of related similar-origin browsing contexts' signal slot
      // list.
      docGroup->ClearSignalSlotList();
    }
    delete DocGroup::sPendingDocGroups;
    DocGroup::sPendingDocGroups = nullptr;
  }

  if (sScheduledMutationObservers) {
    AutoTArray<RefPtr<nsDOMMutationObserver>, 4>* observers =
      sScheduledMutationObservers;
    sScheduledMutationObservers = nullptr;
    for (uint32_t i = 0; i < observers->Length(); ++i) {
      RefPtr<nsDOMMutationObserver> currentObserver =
        static_cast<nsDOMMutationObserver*>((*observers)[i]);
      if (!currentObserver->Suppressed()) {
        currentObserver->HandleMutation();
      } else {
        if (!suppressedObservers) {
          suppressedObservers = new nsTArray<RefPtr<nsDOMMutationObserver> >;
        }
        if (!suppressedObservers->Contains(currentObserver)) {
          suppressedObservers->AppendElement(currentObserver);
        }
      }
    }
    delete observers;
    aAso.CheckForInterrupt();
  }

  if (suppressedObservers) {
    for (uint32_t i = 0; i < suppressedObservers->Length(); ++i) {
      static_cast<nsDOMMutationObserver*>(suppressedObservers->ElementAt(i))->
        RescheduleForRun();
    }
    delete suppressedObservers;
    suppressedObservers = nullptr;
  }

  // Fire slotchange event for each slot in signalList.
  for (uint32_t i = 0; i < signalList.Length(); ++i) {
    signalList[i]->FireSlotChangeEvent();
  }
}

nsDOMMutationRecord*
nsDOMMutationObserver::CurrentRecord(nsAtom* aType)
{
  NS_ASSERTION(sMutationLevel > 0, "Unexpected mutation level!");

  while (mCurrentMutations.Length() < sMutationLevel) {
    mCurrentMutations.AppendElement(static_cast<nsDOMMutationRecord*>(nullptr));
  }

  uint32_t last = sMutationLevel - 1;
  if (!mCurrentMutations[last]) {
    RefPtr<nsDOMMutationRecord> r = new nsDOMMutationRecord(aType, GetParentObject());
    mCurrentMutations[last] = r;
    AppendMutationRecord(r.forget());
    ScheduleForRun();
  }

#ifdef DEBUG
  MOZ_ASSERT(sCurrentlyHandlingObservers->Length() == sMutationLevel);
  for (size_t i = 0; i < sCurrentlyHandlingObservers->Length(); ++i) {
    MOZ_ASSERT(sCurrentlyHandlingObservers->ElementAt(i).Contains(this),
               "MutationObserver should be added as an observer of all the "
               "nested mutations!");
  }
#endif

  NS_ASSERTION(mCurrentMutations[last]->mType == aType,
               "Unexpected MutationRecord type!");

  return mCurrentMutations[last];
}

nsDOMMutationObserver::~nsDOMMutationObserver()
{
  for (int32_t i = 0; i < mReceivers.Count(); ++i) {
    mReceivers[i]->RemoveClones();
  }
}

void
nsDOMMutationObserver::EnterMutationHandling()
{
  ++sMutationLevel;
}

// Leave the current mutation level (there can be several levels if in case
// of nested calls to the nsIMutationObserver methods).
// The most recent mutation record is removed from mCurrentMutations, so
// that is doesn't get modified anymore by receivers.
void
nsDOMMutationObserver::LeaveMutationHandling()
{
  if (sCurrentlyHandlingObservers &&
      sCurrentlyHandlingObservers->Length() == sMutationLevel) {
    nsTArray<RefPtr<nsDOMMutationObserver> >& obs =
      sCurrentlyHandlingObservers->ElementAt(sMutationLevel - 1);
    for (uint32_t i = 0; i < obs.Length(); ++i) {
      nsDOMMutationObserver* o =
        static_cast<nsDOMMutationObserver*>(obs[i]);
      if (o->mCurrentMutations.Length() == sMutationLevel) {
        // It is already in pending mutations.
        o->mCurrentMutations.RemoveElementAt(sMutationLevel - 1);
      }
    }
    sCurrentlyHandlingObservers->RemoveElementAt(sMutationLevel - 1);
  }
  --sMutationLevel;
}

void
nsDOMMutationObserver::AddCurrentlyHandlingObserver(nsDOMMutationObserver* aObserver,
                                                    uint32_t aMutationLevel)
{
  NS_ASSERTION(aMutationLevel > 0, "Unexpected mutation level!");

  if (aMutationLevel > 1) {
    // MutationObserver must be in the currently handling observer list
    // in all the nested levels.
    AddCurrentlyHandlingObserver(aObserver, aMutationLevel - 1);
  }

  if (!sCurrentlyHandlingObservers) {
    sCurrentlyHandlingObservers =
      new AutoTArray<AutoTArray<RefPtr<nsDOMMutationObserver>, 4>, 4>;
  }

  while (sCurrentlyHandlingObservers->Length() < aMutationLevel) {
    sCurrentlyHandlingObservers->InsertElementAt(
      sCurrentlyHandlingObservers->Length());
  }

  uint32_t index = aMutationLevel - 1;
  if (!sCurrentlyHandlingObservers->ElementAt(index).Contains(aObserver)) {
    sCurrentlyHandlingObservers->ElementAt(index).AppendElement(aObserver);
  }
}

void
nsDOMMutationObserver::Shutdown()
{
  delete sCurrentlyHandlingObservers;
  sCurrentlyHandlingObservers = nullptr;
  delete sScheduledMutationObservers;
  sScheduledMutationObservers = nullptr;
}

nsAutoMutationBatch*
nsAutoMutationBatch::sCurrentBatch = nullptr;

void
nsAutoMutationBatch::Done()
{
  if (sCurrentBatch != this) {
    return;
  }

  sCurrentBatch = mPreviousBatch;
  if (mObservers.IsEmpty()) {
    nsDOMMutationObserver::LeaveMutationHandling();
    // Nothing to do.
    return;
  }

  uint32_t len = mObservers.Length();
  for (uint32_t i = 0; i < len; ++i) {
    nsDOMMutationObserver* ob = mObservers[i].mObserver;
    bool wantsChildList = mObservers[i].mWantsChildList;

    RefPtr<nsSimpleContentList> removedList;
    if (wantsChildList) {
      removedList = new nsSimpleContentList(mBatchTarget);
    }

    nsTArray<nsMutationReceiver*> allObservers;
    ob->GetAllSubtreeObserversFor(mBatchTarget, allObservers);

    int32_t j = mFromFirstToLast ? 0 : mRemovedNodes.Length() - 1;
    int32_t end = mFromFirstToLast ? mRemovedNodes.Length() : -1;
    for (; j != end; mFromFirstToLast ? ++j : --j) {
      nsCOMPtr<nsIContent> removed = mRemovedNodes[j];
      if (removedList) {
        removedList->AppendElement(removed);
      }

      if (allObservers.Length()) {
        nsCOMArray<nsMutationReceiver>* transientReceivers =
          ob->mTransientReceivers.LookupForAdd(removed).OrInsert(
            [] () { return new nsCOMArray<nsMutationReceiver>(); });
        for (uint32_t k = 0; k < allObservers.Length(); ++k) {
          nsMutationReceiver* r = allObservers[k];
          nsMutationReceiver* orig = r->GetParent() ? r->GetParent() : r;
          if (ob->GetReceiverFor(removed, false, false) != orig) {
            // Make sure the elements which are removed from the
            // subtree are kept in the same observation set.
            nsMutationReceiver* tr;
            if (orig->Animations()) {
              tr = nsAnimationReceiver::Create(removed, orig);
            } else {
              tr = nsMutationReceiver::Create(removed, orig);
            }
            transientReceivers->AppendObject(tr);
          }
        }
      }
    }
    if (wantsChildList && (mRemovedNodes.Length() || mAddedNodes.Length())) {
      RefPtr<nsSimpleContentList> addedList =
        new nsSimpleContentList(mBatchTarget);
      for (uint32_t i = 0; i < mAddedNodes.Length(); ++i) {
        addedList->AppendElement(mAddedNodes[i]);
      }
      RefPtr<nsDOMMutationRecord> m =
        new nsDOMMutationRecord(nsGkAtoms::childList,
                                ob->GetParentObject());
      m->mTarget = mBatchTarget;
      m->mRemovedNodes = removedList;
      m->mAddedNodes = addedList;
      m->mPreviousSibling = mPrevSibling;
      m->mNextSibling = mNextSibling;
      ob->AppendMutationRecord(m.forget());
    }
    // Always schedule the observer so that transient receivers are
    // removed correctly.
    ob->ScheduleForRun();
  }
  nsDOMMutationObserver::LeaveMutationHandling();
}

nsAutoAnimationMutationBatch*
nsAutoAnimationMutationBatch::sCurrentBatch = nullptr;

void
nsAutoAnimationMutationBatch::Done()
{
  if (sCurrentBatch != this) {
    return;
  }

  sCurrentBatch = nullptr;
  if (mObservers.IsEmpty()) {
    nsDOMMutationObserver::LeaveMutationHandling();
    // Nothing to do.
    return;
  }

  mBatchTargets.Sort(TreeOrderComparator());

  for (nsDOMMutationObserver* ob : mObservers) {
    bool didAddRecords = false;

    for (nsINode* target : mBatchTargets) {
      EntryArray* entries = mEntryTable.Get(target);
      MOZ_ASSERT(entries,
        "Targets in entry table and targets list should match");

      RefPtr<nsDOMMutationRecord> m =
        new nsDOMMutationRecord(nsGkAtoms::animations, ob->GetParentObject());
      m->mTarget = target;

      for (const Entry& e : *entries) {
        if (e.mState == eState_Added) {
          m->mAddedAnimations.AppendElement(e.mAnimation);
        } else if (e.mState == eState_Removed) {
          m->mRemovedAnimations.AppendElement(e.mAnimation);
        } else if (e.mState == eState_RemainedPresent && e.mChanged) {
          m->mChangedAnimations.AppendElement(e.mAnimation);
        }
      }

      if (!m->mAddedAnimations.IsEmpty() ||
          !m->mChangedAnimations.IsEmpty() ||
          !m->mRemovedAnimations.IsEmpty()) {
        ob->AppendMutationRecord(m.forget());
        didAddRecords = true;
      }
    }

    if (didAddRecords) {
      ob->ScheduleForRun();
    }
  }
  nsDOMMutationObserver::LeaveMutationHandling();
}