Source/WTF/wtf/TaggedArrayStoragePtr.h

/*
 * Copyright (C) 2019 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/PtrTag.h>

namespace WTF {

template<typename PtrType>
class TaggedArrayStoragePtr {
public:
    TaggedArrayStoragePtr()
        : m_ptr(tagArrayPtr<PtrType>(nullptr, 0))
    { }

    TaggedArrayStoragePtr(PtrType* ptr, unsigned length)
        : m_ptr(tagArrayPtr(ptr, length))
    { }

    PtrType* get(unsigned length) const { return untagArrayPtr(m_ptr, length); } 
    PtrType* getUnsafe() const { return removeArrayPtrTag(m_ptr); }

    void resize(unsigned oldLength, unsigned newLength)
    {
        m_ptr = retagArrayPtr(m_ptr, oldLength, newLength);
    }
    
    explicit operator bool() const { return !!getUnsafe(); }

private:
    PtrType* m_ptr;
};

}

using WTF::TaggedArrayStoragePtr;