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/*
* Copyright (C) 2018-2021 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. ``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.
*/
#pragma once
#include <wtf/HashTraits.h>
#include <wtf/PtrTag.h>
#include <wtf/StdLibExtras.h>
namespace WTF {
template<PtrTag tag>
class MetaAllocatorPtr {
public:
MetaAllocatorPtr() = default;
MetaAllocatorPtr(std::nullptr_t) { }
static MetaAllocatorPtr makeFromRawPointer(void* ptr) { return MetaAllocatorPtr(ptr); }
template<PtrTag otherTag>
explicit MetaAllocatorPtr(MetaAllocatorPtr<otherTag> other)
: m_ptr(other.template retaggedPtr<tag>())
{ }
explicit MetaAllocatorPtr(uintptr_t ptrAsInt)
: MetaAllocatorPtr(reinterpret_cast<void*>(ptrAsInt))
{ }
template<typename T = void*>
T untaggedPtr() const { return bitwise_cast<T>(untagCodePtr<tag>(m_ptr)); }
template<PtrTag newTag, typename T = void*>
T retaggedPtr() const { return bitwise_cast<T>(retagCodePtr<tag, newTag>(m_ptr)); }
// Disallow any casting operations (except for booleans).
template<typename T, typename = std::enable_if_t<!std::is_same<T, bool>::value>>
operator T() = delete;
explicit operator bool() const { return !!m_ptr; }
bool operator!() const { return !m_ptr; }
bool operator==(MetaAllocatorPtr other) const { return m_ptr == other.m_ptr; }
bool operator!=(MetaAllocatorPtr other) const { return m_ptr != other.m_ptr; }
MetaAllocatorPtr operator+(size_t sizeInBytes) const { return MetaAllocatorPtr(untaggedPtr<uint8_t*>() + sizeInBytes); }
MetaAllocatorPtr operator-(size_t sizeInBytes) const { return MetaAllocatorPtr(untaggedPtr<uint8_t*>() - sizeInBytes); }
MetaAllocatorPtr& operator+=(size_t sizeInBytes)
{
return *this = *this + sizeInBytes;
}
MetaAllocatorPtr& operator-=(size_t sizeInBytes)
{
return *this = *this - sizeInBytes;
}
enum EmptyValueTag { EmptyValue };
enum DeletedValueTag { DeletedValue };
MetaAllocatorPtr(EmptyValueTag)
: m_ptr(emptyValue())
{ }
MetaAllocatorPtr(DeletedValueTag)
: m_ptr(deletedValue())
{ }
bool isEmptyValue() const { return m_ptr == emptyValue(); }
bool isDeletedValue() const { return m_ptr == deletedValue(); }
unsigned hash() const { return PtrHash<void*>::hash(m_ptr); }
private:
explicit MetaAllocatorPtr(void* ptr)
: m_ptr(tagCodePtr<tag>(ptr))
{
assertIsNotTagged(ptr);
}
static void* emptyValue() { return reinterpret_cast<void*>(1); }
static void* deletedValue() { return reinterpret_cast<void*>(2); }
void* m_ptr { nullptr };
};
template<PtrTag tag>
struct MetaAllocatorPtrHash {
static unsigned hash(const MetaAllocatorPtr<tag>& ptr) { return ptr.hash(); }
static bool equal(const MetaAllocatorPtr<tag>& a, const MetaAllocatorPtr<tag>& b)
{
return a == b;
}
static constexpr bool safeToCompareToEmptyOrDeleted = true;
};
template<typename> struct DefaultHash;
template<PtrTag tag> struct DefaultHash<MetaAllocatorPtr<tag>> : MetaAllocatorPtrHash<tag> { };
template<PtrTag tag> struct HashTraits<MetaAllocatorPtr<tag>> : public CustomHashTraits<MetaAllocatorPtr<tag>> { };
} // namespace WTF
using WTF::MetaAllocatorPtr;
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