MetaAllocatorPtr.h [plain text]
#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) { }
explicit MetaAllocatorPtr(void* ptr)
: m_ptr(tagCodePtr<tag>(ptr))
{
assertIsNotTagged(ptr);
}
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)); }
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:
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 const bool safeToCompareToEmptyOrDeleted = true;
};
template<typename T> struct DefaultHash;
template<PtrTag tag> struct DefaultHash<MetaAllocatorPtr<tag>> {
typedef MetaAllocatorPtrHash<tag> Hash;
};
template<PtrTag tag> struct HashTraits<MetaAllocatorPtr<tag>> : public CustomHashTraits<MetaAllocatorPtr<tag>> { };
}
using WTF::MetaAllocatorPtr;