ladybird/AK/NeverDestroyed.h

/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 * 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 THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT HOLDER 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 <AK/Noncopyable.h>
#include <AK/StdLibExtras.h>

namespace AK {

template<typename T>
class NeverDestroyed {
    AK_MAKE_NONCOPYABLE(NeverDestroyed)
    AK_MAKE_NONMOVABLE(NeverDestroyed)
public:
    template<typename... Args>
    NeverDestroyed(Args... args)
    {
        new (storage) T(forward<Args>(args)...);
    }

    ~NeverDestroyed() = default;

    T* operator->() { return &get(); }
    const T* operator->() const { return &get(); }

    T& operator*() { return get(); }
    const T& operator*() const { return get(); }

    T& get() { return reinterpret_cast<T&>(storage); }
    const T& get() const { return reinterpret_cast<T&>(storage); }

private:
    alignas(T) u8 storage[sizeof(T)];
};

}

using AK::NeverDestroyed;