Source/WTF/wtf/RawPtrTraits.h

/*
 * Copyright (C) 2017-2018 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
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 *    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
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
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 */

#pragma once

#include <cstdint>
#include <utility>
#include <wtf/StdLibExtras.h>

namespace WTF {
    
template<typename T>
struct RawPtrTraits {
    template<typename U> using RebindTraits = RawPtrTraits<U>;

    using StorageType = T*;

    template<typename U>
    static ALWAYS_INLINE T* exchange(StorageType& ptr, U&& newValue) { return std::exchange(ptr, newValue); }

    static ALWAYS_INLINE void swap(StorageType& a, StorageType& b) { std::swap(a, b); }
    static ALWAYS_INLINE T* unwrap(const StorageType& ptr) { return ptr; }

    static StorageType hashTableDeletedValue() { return bitwise_cast<StorageType>(static_cast<uintptr_t>(-1)); }
    static ALWAYS_INLINE bool isHashTableDeletedValue(const StorageType& ptr) { return ptr == hashTableDeletedValue(); }
};

} // namespace WTF

using WTF::RawPtrTraits;