third_party/WebKit/Source/core/dom/MutationObserverInterestGroup.cpp

/*
 * Copyright (C) 2011 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
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#include "core/dom/MutationObserverInterestGroup.h"

#include "core/dom/MutationRecord.h"

namespace blink {

MutationObserverInterestGroup* MutationObserverInterestGroup::createIfNeeded(
    Node& target,
    MutationObserver::MutationType type,
    MutationRecordDeliveryOptions oldValueFlag,
    const QualifiedName* attributeName) {
  DCHECK((type == MutationObserver::Attributes && attributeName) ||
         !attributeName);
  HeapHashMap<Member<MutationObserver>, MutationRecordDeliveryOptions>
      observers;
  target.getRegisteredMutationObserversOfType(observers, type, attributeName);
  if (observers.isEmpty())
    return nullptr;

  return new MutationObserverInterestGroup(observers, oldValueFlag);
}

MutationObserverInterestGroup::MutationObserverInterestGroup(
    HeapHashMap<Member<MutationObserver>, MutationRecordDeliveryOptions>&
        observers,
    MutationRecordDeliveryOptions oldValueFlag)
    : m_oldValueFlag(oldValueFlag) {
  DCHECK(!observers.isEmpty());
  m_observers.swap(observers);
}

bool MutationObserverInterestGroup::isOldValueRequested() {
  for (auto& observer : m_observers) {
    if (hasOldValue(observer.value))
      return true;
  }
  return false;
}

void MutationObserverInterestGroup::enqueueMutationRecord(
    MutationRecord* mutation) {
  MutationRecord* mutationWithNullOldValue = nullptr;
  for (auto& iter : m_observers) {
    MutationObserver* observer = iter.key.get();
    if (hasOldValue(iter.value)) {
      observer->enqueueMutationRecord(mutation);
      continue;
    }
    if (!mutationWithNullOldValue) {
      if (mutation->oldValue().isNull())
        mutationWithNullOldValue = mutation;
      else
        mutationWithNullOldValue =
            MutationRecord::createWithNullOldValue(mutation);
    }
    observer->enqueueMutationRecord(mutationWithNullOldValue);
  }
}

DEFINE_TRACE(MutationObserverInterestGroup) {
  visitor->trace(m_observers);
}

}  // namespace blink