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/*
* Copyright (C) 2013-2014 Apple 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. AND ITS 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 APPLE INC. OR ITS 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_Ref_h
#define WTF_Ref_h
#include <wtf/Assertions.h>
#include <wtf/GetPtr.h>
#include <wtf/Noncopyable.h>
#include <wtf/StdLibExtras.h>
#include <wtf/TypeCasts.h>
#if ASAN_ENABLED
extern "C" void __asan_poison_memory_region(void const volatile *addr, size_t size);
extern "C" void __asan_unpoison_memory_region(void const volatile *addr, size_t size);
extern "C" bool __asan_address_is_poisoned(void const volatile *addr);
#endif
namespace WTF {
inline void adopted(const void*) { }
template<typename T> class Ref;
template<typename T> Ref<T> adoptRef(T&);
template<typename T> class Ref {
public:
static constexpr bool isRef = true;
~Ref()
{
#if ASAN_ENABLED
if (__asan_address_is_poisoned(this))
__asan_unpoison_memory_region(this, sizeof(*this));
#endif
if (m_ptr)
m_ptr->deref();
}
Ref(T& object)
: m_ptr(&object)
{
m_ptr->ref();
}
// Use copyRef() instead.
Ref(const Ref& other) = delete;
template<typename U> Ref(const Ref<U>& other) = delete;
Ref(Ref&& other)
: m_ptr(&other.leakRef())
{
ASSERT(m_ptr);
}
template<typename U>
Ref(Ref<U>&& other)
: m_ptr(&other.leakRef())
{
ASSERT(m_ptr);
}
Ref& operator=(T& object)
{
ASSERT(m_ptr);
object.ref();
m_ptr->deref();
m_ptr = &object;
ASSERT(m_ptr);
return *this;
}
// Use copyRef() and the move assignment operators instead.
Ref& operator=(const Ref& reference) = delete;
template<typename U> Ref& operator=(const Ref<U>& reference) = delete;
Ref& operator=(Ref&& reference)
{
ASSERT(m_ptr);
m_ptr->deref();
m_ptr = &reference.leakRef();
ASSERT(m_ptr);
return *this;
}
template<typename U> Ref& operator=(Ref<U>&& reference)
{
ASSERT(m_ptr);
m_ptr->deref();
m_ptr = &reference.leakRef();
ASSERT(m_ptr);
return *this;
}
// Hash table deleted values, which are only constructed and never copied or destroyed.
Ref(HashTableDeletedValueType) : m_ptr(hashTableDeletedValue()) { }
bool isHashTableDeletedValue() const { return m_ptr == hashTableDeletedValue(); }
static T* hashTableDeletedValue() { return reinterpret_cast<T*>(-1); }
Ref(HashTableEmptyValueType) : m_ptr(hashTableEmptyValue()) { }
bool isHashTableEmptyValue() const { return m_ptr == hashTableEmptyValue(); }
static T* hashTableEmptyValue() { return nullptr; }
const T* ptrAllowingHashTableEmptyValue() const { ASSERT(m_ptr || isHashTableEmptyValue()); return m_ptr; }
T* ptrAllowingHashTableEmptyValue() { ASSERT(m_ptr || isHashTableEmptyValue()); return m_ptr; }
void assignToHashTableEmptyValue(Ref&& reference)
{
ASSERT(m_ptr == hashTableEmptyValue());
m_ptr = &reference.leakRef();
ASSERT(m_ptr);
}
T* operator->() const { ASSERT(m_ptr); return m_ptr; }
T* ptr() const { ASSERT(m_ptr); return m_ptr; }
T& get() const { ASSERT(m_ptr); return *m_ptr; }
operator T&() const { ASSERT(m_ptr); return *m_ptr; }
template<typename U> Ref<T> replace(Ref<U>&&) WARN_UNUSED_RETURN;
#if COMPILER_SUPPORTS(CXX_REFERENCE_QUALIFIED_FUNCTIONS)
Ref copyRef() && = delete;
Ref copyRef() const & WARN_UNUSED_RETURN { return Ref(*m_ptr); }
#else
Ref copyRef() const WARN_UNUSED_RETURN { return Ref(*m_ptr); }
#endif
T& leakRef() WARN_UNUSED_RETURN
{
ASSERT(m_ptr);
T& result = *std::exchange(m_ptr, nullptr);
#if ASAN_ENABLED
__asan_poison_memory_region(this, sizeof(*this));
#endif
return result;
}
private:
friend Ref adoptRef<T>(T&);
enum AdoptTag { Adopt };
Ref(T& object, AdoptTag)
: m_ptr(&object)
{
}
T* m_ptr;
};
template<typename T> template<typename U> inline Ref<T> Ref<T>::replace(Ref<U>&& reference)
{
auto oldReference = adoptRef(*m_ptr);
m_ptr = &reference.leakRef();
return oldReference;
}
template<typename T, typename U> inline Ref<T> static_reference_cast(Ref<U>& reference)
{
return Ref<T>(static_cast<T&>(reference.get()));
}
template<typename T, typename U> inline Ref<T> static_reference_cast(Ref<U>&& reference)
{
return adoptRef(static_cast<T&>(reference.leakRef()));
}
template<typename T, typename U> inline Ref<T> static_reference_cast(const Ref<U>& reference)
{
return Ref<T>(static_cast<T&>(reference.copyRef().get()));
}
template <typename T>
struct GetPtrHelper<Ref<T>> {
typedef T* PtrType;
static T* getPtr(const Ref<T>& p) { return const_cast<T*>(p.ptr()); }
};
template <typename T>
struct IsSmartPtr<Ref<T>> {
static const bool value = true;
};
template<typename T>
inline Ref<T> adoptRef(T& reference)
{
adopted(&reference);
return Ref<T>(reference, Ref<T>::Adopt);
}
template<typename T>
inline Ref<T> makeRef(T& reference)
{
return Ref<T>(reference);
}
template<typename ExpectedType, typename ArgType> inline bool is(Ref<ArgType>& source)
{
return is<ExpectedType>(source.get());
}
template<typename ExpectedType, typename ArgType> inline bool is(const Ref<ArgType>& source)
{
return is<ExpectedType>(source.get());
}
} // namespace WTF
using WTF::Ref;
using WTF::adoptRef;
using WTF::makeRef;
using WTF::static_reference_cast;
#endif // WTF_Ref_h
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