text: /*
   * Copyright (C) 2011 Google Inc. All rights reserved.
   *
   * 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.
   *     * Redistributions in binary form must reproduce the above
   * copyright notice, this list of conditions and the following disclaimer
   * in the documentation and/or other materials provided with the
   * distribution.
   *     * Neither the name of Google Inc. nor the names of its
   * contributors may be used to endorse or promote products derived from
   * this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #ifndef THIRD_PARTY_BLINK_RENDERER_CORE_DOM_MUTATION_OBSERVER_H_
  #define THIRD_PARTY_BLINK_RENDERER_CORE_DOM_MUTATION_OBSERVER_H_
  
  #include "base/gtest_prod_util.h"
  #include "third_party/blink/renderer/bindings/core/v8/active_script_wrappable.h"
  #include "third_party/blink/renderer/core/core_export.h"
  #include "third_party/blink/renderer/core/dom/mutation_observer_options.h"
  #include "third_party/blink/renderer/core/execution_context/execution_context.h"
  #include "third_party/blink/renderer/core/execution_context/execution_context_lifecycle_state_observer.h"
  #include "third_party/blink/renderer/platform/bindings/name_client.h"
  #include "third_party/blink/renderer/platform/bindings/script_wrappable.h"
  #include "third_party/blink/renderer/platform/heap/handle.h"
  #include "third_party/blink/renderer/platform/wtf/hash_set.h"
  #include "third_party/blink/renderer/platform/wtf/vector.h"
  
  namespace blink {
  
  class Document;
  class ExceptionState;
  class HTMLSlotElement;
  class MutationObserver;
  class MutationObserverInit;
  class MutationObserverRegistration;
  class MutationRecord;
  class Node;
  class ScriptState;
  class V8MutationCallback;
  
  using MutationObserverSet = HeapHashSet<Member<MutationObserver>>;
  using MutationObserverRegistrationSet =
      HeapHashSet<WeakMember<MutationObserverRegistration>>;
  using MutationObserverVector = HeapVector<Member<MutationObserver>>;
  using MutationRecordVector = HeapVector<Member<MutationRecord>>;
  
  class CORE_EXPORT MutationObserver final
      : public ScriptWrappable,
        public ActiveScriptWrappable<MutationObserver>,
        public ExecutionContextLifecycleStateObserver {
    DEFINE_WRAPPERTYPEINFO();
    USING_GARBAGE_COLLECTED_MIXIN(MutationObserver);
    // Using CancelInspectorAsyncTasks as pre-finalizer to cancel async tasks.
    USING_PRE_FINALIZER(MutationObserver, CancelInspectorAsyncTasks);
  
   public:
    enum ObservationFlags { kSubtree = 1 << 3, kAttributeFilter = 1 << 4 };
  
    enum DeliveryFlags {
      kAttributeOldValue = 1 << 5,
      kCharacterDataOldValue = 1 << 6,
    };
  
    class CORE_EXPORT Delegate : public GarbageCollected<Delegate>,
                                 public NameClient {
     public:
      virtual ~Delegate() = default;
      virtual ExecutionContext* GetExecutionContext() const = 0;
      virtual void Deliver(const MutationRecordVector& records,
                           MutationObserver&) = 0;
      virtual void Trace(Visitor* visitor) {}
      const char* NameInHeapSnapshot() const override {
        return "MutationObserver::Delegate";
      }
    };
  
    class CORE_EXPORT V8DelegateImpl;
  
    static MutationObserver* Create(Delegate*);
    static MutationObserver* Create(ScriptState*, V8MutationCallback*);
    static void DeliverMutations();
    static void EnqueueSlotChange(HTMLSlotElement&);
    static void CleanSlotChangeList(Document&);
  
    MutationObserver(ExecutionContext*, Delegate*);
    ~MutationObserver() override;
  
    void observe(Node*, const MutationObserverInit*, ExceptionState&);
    MutationRecordVector takeRecords();
    void disconnect();
    void ObservationStarted(MutationObserverRegistration*);
    void ObservationEnded(MutationObserverRegistration*);
    void EnqueueMutationRecord(MutationRecord*);
    void SetHasTransientRegistration();
  
    HeapHashSet<Member<Node>> GetObservedNodes() const;
  
    bool HasPendingActivity() const override { return !records_.IsEmpty(); }
  
    void ContextLifecycleStateChanged(mojom::FrameLifecycleState) final;
    void ContextDestroyed() final {}
  
    void Trace(Visitor*) override;
  
   private:
    struct ObserverLessThan;
  
    void Deliver();
    void CancelInspectorAsyncTasks();
  
    Member<Delegate> delegate_;
    HeapVector<Member<MutationRecord>> records_;
    MutationObserverRegistrationSet registrations_;
    unsigned priority_;
  
    FRIEND_TEST_ALL_PREFIXES(MutationObserverTest, DisconnectCrash);
  };
  
  }  // namespace blink
  
  #endif  // THIRD_PARTY_BLINK_RENDERER_CORE_DOM_MUTATION_OBSERVER_H_
  