Implement WTF::WeakPtr in terms of base::WeakPtr

third_party/WebKit/Source/wtf/WeakPtr.h

 /*
  * Copyright (C) 2013 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. 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.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 APPLE INC. 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 WTF_WeakPtr_h
 #define WTF_WeakPtr_h
 
+#include "base/memory/weak_ptr.h"
 #include "wtf/Noncopyable.h"
-#include "wtf/PassRefPtr.h"
-#include "wtf/RefPtr.h"
-#include "wtf/ThreadSafeRefCounted.h"
-#include "wtf/Threading.h"
 
 namespace WTF {
 
 template<typename T>
-class WeakReference : public ThreadSafeRefCounted<WeakReference<T>> {
-    WTF_MAKE_NONCOPYABLE(WeakReference<T>);
-    USING_FAST_MALLOC(WeakReference);
-public:
-    static PassRefPtr<WeakReference<T>> create(T* ptr) { return adoptRef(new WeakReference(ptr)); }
-    static PassRefPtr<WeakReference<T>> createUnbound() { return adoptRef(new WeakReference()); }
-
-    T* get() const
-    {
-#if DCHECK_IS_ON()
-        DCHECK_EQ(m_boundThread, currentThread());
-#endif
-        return m_ptr;
-    }
-
-    void clear()
-    {
-#if DCHECK_IS_ON()
-        DCHECK_EQ(m_boundThread, currentThread());
-#endif
-        m_ptr = 0;
-    }
-
-    void bindTo(T* ptr)
-    {
-        DCHECK(!m_ptr);
-#if DCHECK_IS_ON()
-        m_boundThread = currentThread();
-#endif
-        m_ptr = ptr;
-    }
-
-private:
-    WeakReference() : m_ptr(0) { }
-
-    explicit WeakReference(T* ptr)
-        : m_ptr(ptr)
-#if DCHECK_IS_ON()
-        , m_boundThread(currentThread())
-#endif
-    {
-    }
-
-    T* m_ptr;
-#if DCHECK_IS_ON()
-    ThreadIdentifier m_boundThread;
-#endif
-};
-
-template<typename T>
-class WeakPtr {
-    USING_FAST_MALLOC(WeakPtr);
-public:
-    WeakPtr() { }
-    WeakPtr(std::nullptr_t) { }
-    WeakPtr(PassRefPtr<WeakReference<T>> ref) : m_ref(ref) { }
-
-    T* get() const { return m_ref ? m_ref->get() : 0; }
-    void clear() { m_ref.clear(); }
-
-    T& operator*() const
-    {
-        DCHECK(get());
-        return *get();
-    }
-
-    T* operator->() const
-    {
-        DCHECK(get());
-        return get();
-    }
-
-    explicit operator bool() const { return get(); }
-
-private:
-    RefPtr<WeakReference<T>> m_ref;
-};
-
-template<typename T, typename U> inline bool operator==(const WeakPtr<T>& a, const WeakPtr<U>& b)
-{
-    return a.get() == b.get();
-}
-
-template<typename T, typename U> inline bool operator!=(const WeakPtr<T>& a, const WeakPtr<U>& b)
-{
-    return a.get() != b.get();
-}
+using WeakPtr = base::WeakPtr<T>;
 
 template<typename T>
 class WeakPtrFactory {
     WTF_MAKE_NONCOPYABLE(WeakPtrFactory<T>);
     USING_FAST_MALLOC(WeakPtrFactory);
 public:
-    explicit WeakPtrFactory(T* ptr) : m_ref(WeakReference<T>::create(ptr)) { }
+    explicit WeakPtrFactory(T* ptr) : m_factory(ptr) { }
 
-    WeakPtrFactory(PassRefPtr<WeakReference<T>> ref, T* ptr)
-        : m_ref(ref)
-    {
-        m_ref->bindTo(ptr);
-    }
-
-    ~WeakPtrFactory() { m_ref->clear(); }
-
-    // We should consider having createWeakPtr populate m_ref the first time createWeakPtr is called.
-    WeakPtr<T> createWeakPtr() { return WeakPtr<T>(m_ref); }
+    WeakPtr<T> createWeakPtr() { return m_factory.GetWeakPtr(); }
 
     void revokeAll()
     {
-        T* ptr = m_ref->get();
-        m_ref->clear();
-        // We create a new WeakReference so that future calls to createWeakPtr() create nonzero WeakPtrs.
-        m_ref = WeakReference<T>::create(ptr);
+        m_factory.InvalidateWeakPtrs();
     }
 
     bool hasWeakPtrs() const
     {
-        return m_ref->refCount() > 1;
+        return m_factory.HasWeakPtrs();
     }
 
 private:
-    RefPtr<WeakReference<T>> m_ref;
+    base::WeakPtrFactory<T> m_factory;
 };
 
 } // namespace WTF
 
 using WTF::WeakPtr;
 using WTF::WeakPtrFactory;
-using WTF::WeakReference;
 
 #endif