third_party/blink/renderer/core/dom/mutation_observer_interest_group.cc

/*
 * Copyright (C) 2011 Google Inc. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
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 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
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 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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#include "third_party/blink/renderer/core/dom/mutation_observer_interest_group.h"

#include "third_party/blink/renderer/core/dom/mutation_record.h"

namespace blink {

MutationObserverInterestGroup* MutationObserverInterestGroup::CreateIfNeeded(
    Node& target,
    MutationType type,
    MutationRecordDeliveryOptions old_value_flag,
    const QualifiedName* attribute_name) {
  DCHECK((type == kMutationTypeAttributes && attribute_name) ||
         !attribute_name);
  HeapHashMap<Member<MutationObserver>, MutationRecordDeliveryOptions>
      observers;
  target.GetRegisteredMutationObserversOfType(observers, type, attribute_name);
  if (observers.IsEmpty())
    return nullptr;

  return new MutationObserverInterestGroup(observers, old_value_flag);
}

MutationObserverInterestGroup::MutationObserverInterestGroup(
    HeapHashMap<Member<MutationObserver>, MutationRecordDeliveryOptions>&
        observers,
    MutationRecordDeliveryOptions old_value_flag)
    : old_value_flag_(old_value_flag) {
  DCHECK(!observers.IsEmpty());
  observers_.swap(observers);
}

bool MutationObserverInterestGroup::IsOldValueRequested() {
  for (auto& observer : observers_) {
    if (HasOldValue(observer.value))
      return true;
  }
  return false;
}

void MutationObserverInterestGroup::EnqueueMutationRecord(
    MutationRecord* mutation) {
  MutationRecord* mutation_with_null_old_value = nullptr;
  for (auto& iter : observers_) {
    MutationObserver* observer = iter.key.Get();
    if (HasOldValue(iter.value)) {
      observer->EnqueueMutationRecord(mutation);
      continue;
    }
    if (!mutation_with_null_old_value) {
      if (mutation->oldValue().IsNull())
        mutation_with_null_old_value = mutation;
      else
        mutation_with_null_old_value =
            MutationRecord::CreateWithNullOldValue(mutation);
    }
    observer->EnqueueMutationRecord(mutation_with_null_old_value);
  }
}

void MutationObserverInterestGroup::Trace(blink::Visitor* visitor) {
  visitor->Trace(observers_);
}

}  // namespace blink