363 lines
12 KiB
C++
363 lines
12 KiB
C++
/*
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* Copyright (C) 2011-2019 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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#include <wtf/StdLibExtras.h>
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#include <wtf/Vector.h>
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// This implements a reference counted array for POD** values, which is optimized for:
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// - An empty array only uses one word.
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// - A copy of the array only uses one word (i.e. assignment means aliasing).
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// - The vector can't grow beyond 2^32-1 elements.
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// - In all other regards this has similar space usage to a Vector.
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//
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// ** This could be modified to support non-POD values quite easily. It just
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// hasn't been, so far, because there has been no need. Moreover, even now,
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// it's used for things that aren't quite POD according to the official
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// defintion, such as JSC::Instruction.
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namespace WTF {
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DECLARE_ALLOCATOR_WITH_HEAP_IDENTIFIER(RefCountedArray);
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template<typename T, typename PtrTraits = RawPtrTraits<T>>
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class RefCountedArray {
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enum CommonCopyConstructorTag { CommonCopyConstructor };
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public:
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using iterator = T*;
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using const_iterator = const T*;
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using reverse_iterator = std::reverse_iterator<iterator>;
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using const_reverse_iterator = std::reverse_iterator<const_iterator>;
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RefCountedArray() = default;
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RefCountedArray(const RefCountedArray& other)
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: RefCountedArray(CommonCopyConstructor, other)
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{ }
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template<typename OtherTraits>
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RefCountedArray(const RefCountedArray<T, OtherTraits>& other)
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: RefCountedArray(CommonCopyConstructor, other)
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{ }
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RefCountedArray(RefCountedArray&& other)
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: m_data(PtrTraits::exchange(other.m_data, nullptr))
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{ }
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explicit RefCountedArray(size_t size)
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{
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if (!size) {
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// NOTE: JSC's LowLevelInterpreter relies on this being nullptr when the size is zero.
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PtrTraits::exchange(m_data, nullptr);
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return;
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}
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m_data = allocateUninitializedData(size);
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VectorTypeOperations<T>::initializeIfNonPOD(begin(), end());
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}
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template<typename OtherTraits = PtrTraits>
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RefCountedArray<T, OtherTraits> clone() const
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{
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RefCountedArray<T, OtherTraits> result(size());
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const T* data = this->data();
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T* resultData = result.data();
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for (unsigned i = size(); i--;)
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resultData[i] = data[i];
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return result;
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}
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template<size_t inlineCapacity, typename OverflowHandler>
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explicit RefCountedArray(const Vector<T, inlineCapacity, OverflowHandler>& other)
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{
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if (other.isEmpty()) {
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PtrTraits::exchange(m_data, nullptr);
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return;
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}
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T* data = allocateUninitializedData(other.size());
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m_data = data;
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VectorTypeOperations<T>::uninitializedCopy(other.begin(), other.end(), data);
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}
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template<size_t inlineCapacity, typename OverflowHandler>
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explicit RefCountedArray(Vector<T, inlineCapacity, OverflowHandler>&& other)
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{
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Vector<T, inlineCapacity, OverflowHandler> vector(WTFMove(other));
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if (vector.isEmpty()) {
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PtrTraits::exchange(m_data, nullptr);
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return;
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}
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T* data = allocateUninitializedData(vector.size());
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m_data = data;
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for (unsigned index = 0; index < vector.size(); ++index)
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new (data + index) T(WTFMove(vector[index]));
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}
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template<typename OtherTraits = PtrTraits>
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RefCountedArray& operator=(const RefCountedArray<T, OtherTraits>& other)
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{
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return assign<OtherTraits>(other);
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}
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RefCountedArray& operator=(const RefCountedArray& other)
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{
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return assign<PtrTraits>(other);
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}
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template<size_t inlineCapacity, typename OverflowHandler>
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RefCountedArray& operator=(const Vector<T, inlineCapacity, OverflowHandler>& other)
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{
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T* oldData = data();
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if (other.isEmpty())
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PtrTraits::exchange(m_data, nullptr);
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else {
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T* data = allocateUninitializedData(other.size());
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m_data = data;
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VectorTypeOperations<T>::uninitializedCopy(other.begin(), other.end(), data);
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}
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if (!oldData)
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return *this;
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unsigned refCount = Header::fromPayload(oldData)->refCount - 1;
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if (refCount) {
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Header::fromPayload(oldData)->refCount = refCount;
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return *this;
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}
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VectorTypeOperations<T>::destruct(oldData, oldData + Header::fromPayload(oldData)->length);
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RefCountedArrayMalloc::free(Header::fromPayload(oldData));
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return *this;
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}
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template<size_t inlineCapacity, typename OverflowHandler>
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RefCountedArray& operator=(Vector<T, inlineCapacity, OverflowHandler>&& other)
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{
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Vector<T, inlineCapacity, OverflowHandler> vector(WTFMove(other));
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T* oldData = data();
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if (vector.isEmpty())
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PtrTraits::exchange(m_data, nullptr);
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else {
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T* data = allocateUninitializedData(vector.size());
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m_data = data;
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for (unsigned index = 0; index < vector.size(); ++index)
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new (data + index) T(WTFMove(vector[index]));
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}
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if (!oldData)
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return *this;
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unsigned refCount = Header::fromPayload(oldData)->refCount - 1;
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if (refCount) {
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Header::fromPayload(oldData)->refCount = refCount;
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return *this;
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}
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VectorTypeOperations<T>::destruct(oldData, oldData + Header::fromPayload(oldData)->length);
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RefCountedArrayMalloc::free(Header::fromPayload(oldData));
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return *this;
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}
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~RefCountedArray()
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{
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if (!m_data)
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return;
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T* data = this->data();
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unsigned refCount = Header::fromPayload(data)->refCount - 1;
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if (refCount) {
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Header::fromPayload(data)->refCount = refCount;
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return;
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}
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VectorTypeOperations<T>::destruct(begin(), end());
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RefCountedArrayMalloc::free(Header::fromPayload(data));
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}
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unsigned refCount() const
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{
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if (!m_data)
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return 0;
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return Header::fromPayload(data())->refCount;
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}
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size_t size() const
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{
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if (!m_data)
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return 0;
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return Header::fromPayload(data())->length;
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}
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bool isEmpty() const { return size() == 0; }
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size_t byteSize() const { return size() * sizeof(T); }
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T* data() { return PtrTraits::unwrap(m_data); }
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iterator begin() { return data(); }
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iterator end()
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{
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if (!m_data)
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return 0;
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T* data = this->data();
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return data + Header::fromPayload(data)->length;
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}
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const T* data() const { return const_cast<RefCountedArray*>(this)->data(); }
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const_iterator begin() const { return const_cast<RefCountedArray*>(this)->begin(); }
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const_iterator end() const { return const_cast<RefCountedArray*>(this)->end(); }
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reverse_iterator rbegin() { return reverse_iterator(end()); }
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reverse_iterator rend() { return reverse_iterator(begin()); }
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const_reverse_iterator rbegin() const { return const_reverse_iterator(end()); }
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const_reverse_iterator rend() const { return const_reverse_iterator(begin()); }
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T& at(size_t i)
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{
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ASSERT_WITH_SECURITY_IMPLICATION(i < size());
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return begin()[i];
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}
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const T& at(size_t i) const
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{
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ASSERT_WITH_SECURITY_IMPLICATION(i < size());
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return begin()[i];
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}
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T& operator[](size_t i) { return at(i); }
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const T& operator[](size_t i) const { return at(i); }
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T& first() { return (*this)[0]; }
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const T& first() const { return (*this)[0]; }
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T& last() { return (*this)[size() - 1]; }
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const T& last() const { return (*this)[size() - 1]; }
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void fill(const T& val)
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{
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std::fill(begin(), end(), val);
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}
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void swap(RefCountedArray& other)
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{
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PtrTraits::swap(m_data, other.m_data);
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}
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template<typename OtherTraits = PtrTraits>
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bool operator==(const RefCountedArray<T, OtherTraits>& other) const
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{
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T* data = const_cast<T*>(this->data());
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T* otherData = const_cast<T*>(other.data());
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if (data == otherData)
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return true;
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if (!data || !otherData)
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return false;
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unsigned length = Header::fromPayload(data)->length;
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if (length != Header::fromPayload(otherData)->length)
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return false;
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for (unsigned i = 0; i < length; ++i) {
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if (data[i] != otherData[i])
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return false;
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}
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return true;
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}
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bool operator==(const RefCountedArray& other) const { return this->operator==<PtrTraits>(other); }
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private:
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static T* allocateUninitializedData(unsigned length)
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{
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T* data = (static_cast<Header*>(RefCountedArrayMalloc::malloc(Header::size() + sizeof(T) * length)))->payload();
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Header::fromPayload(data)->refCount = 1;
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Header::fromPayload(data)->length = length;
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ASSERT(Header::fromPayload(data)->length == length);
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return data;
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}
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template<typename OtherTraits = PtrTraits>
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RefCountedArray& assign(const RefCountedArray<T, OtherTraits>& other)
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{
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T* oldData = data();
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T* otherData = const_cast<T*>(other.data());
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if (otherData)
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Header::fromPayload(otherData)->refCount++;
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m_data = otherData;
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if (!oldData)
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return *this;
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unsigned refCount = Header::fromPayload(oldData)->refCount - 1;
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if (refCount) {
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Header::fromPayload(oldData)->refCount = refCount;
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return *this;
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}
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VectorTypeOperations<T>::destruct(oldData, oldData + Header::fromPayload(oldData)->length);
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RefCountedArrayMalloc::free(Header::fromPayload(oldData));
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return *this;
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}
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struct Header {
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unsigned refCount;
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unsigned length;
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static constexpr size_t size()
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{
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return (sizeof(Header) + 7) & ~7;
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}
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static ptrdiff_t offsetOfLength() { return OBJECT_OFFSETOF(Header, length); }
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T* payload()
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{
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char* result = reinterpret_cast<char*>(this) + size();
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ASSERT(!(bitwise_cast<uintptr_t>(result) & 7));
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return reinterpret_cast_ptr<T*>(result);
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}
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static Header* fromPayload(T* payload)
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{
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return reinterpret_cast_ptr<Header*>(reinterpret_cast<char*>(payload) - size());
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}
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static const Header* fromPayload(const T* payload)
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{
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return fromPayload(const_cast<T*>(payload));
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}
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};
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template<typename OtherTraits>
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RefCountedArray(CommonCopyConstructorTag, const RefCountedArray<T, OtherTraits>& other)
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: m_data(const_cast<T*>(other.data()))
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{
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if (m_data)
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Header::fromPayload(data())->refCount++;
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}
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friend class JSC::LLIntOffsetsExtractor;
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typename PtrTraits::StorageType m_data { nullptr };
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};
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} // namespace WTF
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using WTF::RefCountedArray;
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