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/*
* 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 SKY_ENGINE_WTF_WEAKPTR_H_
#define SKY_ENGINE_WTF_WEAKPTR_H_
#include "sky/engine/wtf/Noncopyable.h"
#include "sky/engine/wtf/PassRefPtr.h"
#include "sky/engine/wtf/RefPtr.h"
#include "sky/engine/wtf/ThreadSafeRefCounted.h"
#include "sky/engine/wtf/Threading.h"
namespace WTF {
template<typename T>
class WeakReference : public ThreadSafeRefCounted<WeakReference<T> > {
WTF_MAKE_NONCOPYABLE(WeakReference<T>);
WTF_MAKE_FAST_ALLOCATED;
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
{
ASSERT(m_boundThread == currentThread());
return m_ptr;
}
void clear()
{
ASSERT(m_boundThread == currentThread());
m_ptr = 0;
}
void bindTo(T* ptr)
{
ASSERT(!m_ptr);
#if ENABLE(ASSERT)
m_boundThread = currentThread();
#endif
m_ptr = ptr;
}
private:
WeakReference() : m_ptr(0) { }
explicit WeakReference(T* ptr)
: m_ptr(ptr)
#if ENABLE(ASSERT)
, m_boundThread(currentThread())
#endif
{
}
T* m_ptr;
#if ENABLE(ASSERT)
ThreadIdentifier m_boundThread;
#endif
};
template<typename T>
class WeakPtr {
WTF_MAKE_FAST_ALLOCATED;
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
{
ASSERT(get());
return get();
}
typedef RefPtr<WeakReference<T> > (WeakPtr::*UnspecifiedBoolType);
operator UnspecifiedBoolType() const { return get() ? &WeakPtr::m_ref : 0; }
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();
}
template<typename T>
class WeakPtrFactory {
WTF_MAKE_NONCOPYABLE(WeakPtrFactory<T>);
WTF_MAKE_FAST_ALLOCATED;
public:
explicit WeakPtrFactory(T* ptr) : m_ref(WeakReference<T>::create(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); }
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);
}
private:
RefPtr<WeakReference<T> > m_ref;
};
} // namespace WTF
using WTF::WeakPtr;
using WTF::WeakPtrFactory;
using WTF::WeakReference;
#endif // SKY_ENGINE_WTF_WEAKPTR_H_