122 lines
3.7 KiB
C++
122 lines
3.7 KiB
C++
/*
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* Copyright (C) 2020 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. ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <wtf/FastMalloc.h>
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#include <wtf/RawPtrTraits.h>
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namespace WTF {
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// The purpose of this class is to ensure that the wrapped pointer will never be
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// used uninitialized.
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template <typename T> class NakedRef {
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WTF_MAKE_FAST_ALLOCATED;
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public:
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ALWAYS_INLINE NakedRef(T& ref) : m_ptr(&ref) { }
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ALWAYS_INLINE NakedRef(const NakedRef&) = delete;
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template<typename U> NakedRef(const NakedRef<U>&) = delete;
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ALWAYS_INLINE NakedRef(NakedRef&& other)
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: m_ptr(&other.leakRef())
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{
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ASSERT(m_ptr);
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}
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template<typename U>
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NakedRef(NakedRef<U>&& other)
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: m_ptr(&other.leakRef())
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{
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ASSERT(m_ptr);
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}
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ALWAYS_INLINE T* operator->() const { ASSERT(m_ptr); return m_ptr; }
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T* ptr() const RETURNS_NONNULL { ASSERT(m_ptr); return m_ptr; }
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T& get() const { return *m_ptr; }
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operator T&() const { ASSERT(m_ptr); return *m_ptr; }
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bool operator!() const { ASSERT(m_ptr); return !*m_ptr; }
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NakedRef copyRef() && = delete;
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NakedRef copyRef() const & WARN_UNUSED_RETURN { return NakedRef(*m_ptr); }
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NakedRef& operator=(T&);
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NakedRef& operator=(NakedRef&&);
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template<typename U> NakedRef& operator=(NakedRef<U>&&);
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// Use copyRef() and the move assignment operators instead.
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NakedRef& operator=(const NakedRef&) = delete;
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template<typename X> NakedRef& operator=(const NakedRef<X>&) = delete;
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template<typename U> void swap(NakedRef<U>&);
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T& leakRef() WARN_UNUSED_RETURN
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{
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ASSERT(m_ptr);
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T& result = *RawPtrTraits<T>::exchange(m_ptr, nullptr);
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return result;
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}
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private:
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T* m_ptr;
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};
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template<typename T> inline NakedRef<T>& NakedRef<T>::operator=(NakedRef&& reference)
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{
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NakedRef movedReference = WTFMove(reference);
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swap(movedReference);
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return *this;
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}
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template<typename T> inline NakedRef<T>& NakedRef<T>::operator=(T& ref)
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{
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NakedRef copiedReference = ref;
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swap(copiedReference);
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return *this;
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}
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template<typename T> template<typename U> inline NakedRef<T>& NakedRef<T>::operator=(NakedRef<U>&& other)
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{
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NakedRef ref = WTFMove(other);
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swap(ref);
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return *this;
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}
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template<class T>
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template<class U>
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inline void NakedRef<T>::swap(NakedRef<U>& other)
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{
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std::swap(m_ptr, other.m_ptr);
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}
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template<class T, class U> inline void swap(NakedRef<T>& a, NakedRef<U>& b)
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{
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a.swap(b);
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}
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} // namespace WTF
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using WTF::NakedRef;
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