309 lines
9.8 KiB
C++
309 lines
9.8 KiB
C++
/*
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* Copyright (C) 2021 Apple Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
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* THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <atomic>
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#include <wtf/Forward.h>
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#include <wtf/HashTraits.h>
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#include <wtf/RawPtrTraits.h>
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#if ASSERT_ENABLED
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#include <wtf/Threading.h>
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#endif
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namespace WTF {
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template<typename T, typename PtrTraits>
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class CheckedRef {
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WTF_MAKE_FAST_ALLOCATED;
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public:
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~CheckedRef()
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{
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unpoison(*this);
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if (auto* ptr = PtrTraits::exchange(m_ptr, nullptr))
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PtrTraits::unwrap(ptr)->decrementPtrCount();
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}
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CheckedRef(T& object)
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: m_ptr(&object)
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{
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PtrTraits::unwrap(m_ptr)->incrementPtrCount();
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}
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ALWAYS_INLINE CheckedRef(const CheckedRef& other)
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: m_ptr { PtrTraits::unwrap(other.m_ptr) }
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{
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PtrTraits::unwrap(m_ptr)->incrementPtrCount();
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}
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template<typename OtherType, typename OtherPtrTraits>
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CheckedRef(const CheckedRef<OtherType, OtherPtrTraits>& other)
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: m_ptr { PtrTraits::unwrap(other.m_ptr) }
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{
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PtrTraits::unwrap(m_ptr)->incrementPtrCount();
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}
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ALWAYS_INLINE CheckedRef(CheckedRef&& other)
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: m_ptr { other.releasePtr() }
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{
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ASSERT(m_ptr);
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}
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template<typename OtherType, typename OtherPtrTraits>
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CheckedRef(CheckedRef<OtherType, OtherPtrTraits>&& other)
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: m_ptr { other.releasePtr() }
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{
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ASSERT(m_ptr);
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}
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CheckedRef(HashTableDeletedValueType) : m_ptr(PtrTraits::hashTableDeletedValue()) { }
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bool isHashTableDeletedValue() const { return PtrTraits::isHashTableDeletedValue(m_ptr); }
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CheckedRef(HashTableEmptyValueType) : m_ptr(hashTableEmptyValue()) { }
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bool isHashTableEmptyValue() const { return m_ptr == hashTableEmptyValue(); }
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static T* hashTableEmptyValue() { return nullptr; }
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const T* ptrAllowingHashTableEmptyValue() const { ASSERT(m_ptr || isHashTableEmptyValue()); return PtrTraits::unwrap(m_ptr); }
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T* ptrAllowingHashTableEmptyValue() { ASSERT(m_ptr || isHashTableEmptyValue()); return PtrTraits::unwrap(m_ptr); }
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ALWAYS_INLINE const T* ptr() const { return PtrTraits::unwrap(m_ptr); }
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ALWAYS_INLINE T* ptr() { return PtrTraits::unwrap(m_ptr); }
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ALWAYS_INLINE const T& get() const { ASSERT(ptr()); return *ptr(); }
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ALWAYS_INLINE T& get() { ASSERT(ptr()); return *ptr(); }
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ALWAYS_INLINE const T* operator->() const { return ptr(); }
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ALWAYS_INLINE T* operator->() { return ptr(); }
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ALWAYS_INLINE operator const T&() const { return get(); }
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ALWAYS_INLINE operator T&() { return get(); }
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ALWAYS_INLINE bool operator!() const { return !get(); }
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CheckedRef& operator=(T& reference)
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{
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unpoison(*this);
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CheckedRef copy { reference };
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PtrTraits::swap(m_ptr, copy.m_ptr);
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return *this;
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}
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CheckedRef& operator=(const CheckedRef& other)
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{
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unpoison(*this);
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CheckedRef copy { other };
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PtrTraits::swap(m_ptr, copy.m_ptr);
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return *this;
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}
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template<typename OtherType, typename OtherPtrTraits> CheckedRef& operator=(const CheckedRef<OtherType, OtherPtrTraits>& other)
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{
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unpoison(*this);
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CheckedRef copy { other };
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PtrTraits::swap(m_ptr, copy.m_ptr);
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return *this;
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}
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CheckedRef& operator=(CheckedRef&& other)
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{
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unpoison(*this);
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CheckedRef moved { WTFMove(other) };
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PtrTraits::swap(m_ptr, moved.m_ptr);
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return *this;
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}
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template<typename OtherType, typename OtherPtrTraits> CheckedRef& operator=(CheckedRef<OtherType, OtherPtrTraits>&& other)
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{
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unpoison(*this);
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CheckedRef moved { WTFMove(other) };
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PtrTraits::swap(m_ptr, moved.m_ptr);
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return *this;
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}
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private:
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template<typename OtherType, typename OtherPtrTraits> friend class CheckedRef;
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template<typename OtherType, typename OtherPtrTraits> friend class CheckedPtr;
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T* releasePtr()
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{
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T* ptr = PtrTraits::exchange(m_ptr, nullptr);
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poison(*this);
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return ptr;
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}
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#if ASAN_ENABLED
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template <typename ObjectType>
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void poison(ObjectType& object)
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{
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__asan_poison_memory_region(&object, sizeof(ObjectType));
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}
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template <typename ObjectType>
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void unpoison(ObjectType& object)
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{
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if (__asan_address_is_poisoned(&object))
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__asan_unpoison_memory_region(&object, sizeof(ObjectType));
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}
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#else
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template <typename ObjectType> void poison(ObjectType&) { }
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template <typename ObjectType> void unpoison(ObjectType&) { }
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#endif
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typename PtrTraits::StorageType m_ptr;
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};
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template <typename T, typename PtrTraits>
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struct GetPtrHelper<CheckedRef<T, PtrTraits>> {
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typedef T* PtrType;
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static T* getPtr(const CheckedRef<T, PtrTraits>& p) { return const_cast<T*>(p.ptr()); }
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};
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template <typename T, typename U>
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struct IsSmartPtr<CheckedRef<T, U>> {
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static constexpr bool value = true;
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};
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template<typename ExpectedType, typename ArgType, typename ArgPtrTraits>
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inline bool is(CheckedRef<ArgType, ArgPtrTraits>& source)
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{
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return is<ExpectedType>(source.get());
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}
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template<typename ExpectedType, typename ArgType, typename ArgPtrTraits>
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inline bool is(const CheckedRef<ArgType, ArgPtrTraits>& source)
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{
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return is<ExpectedType>(source.get());
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}
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template<typename P> struct CheckedRefHashTraits : SimpleClassHashTraits<CheckedRef<P>> {
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static constexpr bool emptyValueIsZero = true;
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static CheckedRef<P> emptyValue() { return HashTableEmptyValue; }
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template <typename>
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static void constructEmptyValue(CheckedRef<P>& slot)
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{
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new (NotNull, std::addressof(slot)) CheckedRef<P>(HashTableEmptyValue);
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}
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static constexpr bool hasIsEmptyValueFunction = true;
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static bool isEmptyValue(const CheckedRef<P>& value) { return value.isHashTableEmptyValue(); }
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using PeekType = P*;
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static PeekType peek(const CheckedRef<P>& value) { return const_cast<PeekType>(value.ptrAllowingHashTableEmptyValue()); }
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static PeekType peek(P* value) { return value; }
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using TakeType = CheckedPtr<P>;
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static TakeType take(CheckedRef<P>&& value) { return isEmptyValue(value) ? nullptr : CheckedPtr<P>(WTFMove(value)); }
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};
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template<typename P> struct HashTraits<CheckedRef<P>> : CheckedRefHashTraits<P> { };
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template<typename P> struct PtrHash<CheckedRef<P>> : PtrHashBase<CheckedRef<P>, IsSmartPtr<CheckedRef<P>>::value> {
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static constexpr bool safeToCompareToEmptyOrDeleted = false;
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};
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template<typename P> struct DefaultHash<CheckedRef<P>> : PtrHash<CheckedRef<P>> { };
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template <typename StorageType, typename PtrCounterType> class CanMakeCheckedPtrBase {
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public:
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~CanMakeCheckedPtrBase() { RELEASE_ASSERT(!m_count); }
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PtrCounterType ptrCount() const { return m_count; }
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void incrementPtrCount() { ++m_count; }
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void decrementPtrCount() { ASSERT(m_count); --m_count; }
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private:
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StorageType m_count { 0 };
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};
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template <typename IntegralType>
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class SingleThreadIntegralWrapper {
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public:
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SingleThreadIntegralWrapper(IntegralType);
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operator IntegralType() const;
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bool operator!() const;
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SingleThreadIntegralWrapper& operator++();
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SingleThreadIntegralWrapper& operator--();
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private:
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#if ASSERT_ENABLED && !USE(WEB_THREAD)
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void assertThread() const { ASSERT(m_thread.ptr() == &Thread::current()); }
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#else
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constexpr void assertThread() const { }
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#endif
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IntegralType m_value;
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#if ASSERT_ENABLED && !USE(WEB_THREAD)
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Ref<Thread> m_thread;
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#endif
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};
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template <typename IntegralType>
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inline SingleThreadIntegralWrapper<IntegralType>::SingleThreadIntegralWrapper(IntegralType value)
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: m_value { value }
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#if ASSERT_ENABLED && !USE(WEB_THREAD)
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, m_thread { Thread::current() }
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#endif
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{ }
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template <typename IntegralType>
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inline SingleThreadIntegralWrapper<IntegralType>::operator IntegralType() const
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{
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assertThread();
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return m_value;
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}
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template <typename IntegralType>
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inline bool SingleThreadIntegralWrapper<IntegralType>::operator!() const
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{
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assertThread();
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return !m_value;
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}
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template <typename IntegralType>
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inline SingleThreadIntegralWrapper<IntegralType>& SingleThreadIntegralWrapper<IntegralType>::operator++()
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{
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assertThread();
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m_value++;
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return *this;
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}
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template <typename IntegralType>
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inline SingleThreadIntegralWrapper<IntegralType>& SingleThreadIntegralWrapper<IntegralType>::operator--()
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{
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assertThread();
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m_value--;
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return *this;
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}
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using CanMakeCheckedPtr = CanMakeCheckedPtrBase<SingleThreadIntegralWrapper<uint16_t>, uint16_t>;
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using CanMakeThreadSafeCheckedPtr = CanMakeCheckedPtrBase<std::atomic<uint16_t>, uint16_t>;
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} // namespace WTF
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using WTF::CanMakeCheckedPtr;
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using WTF::CanMakeThreadSafeCheckedPtr;
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using WTF::CheckedRef;
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