Weakable.h

#pragma once

#include "Assertions.h"
#include "RefPtr.h"
#include "RefCounted.h"

namespace AK {

template<typename T>
class Weakable;
template<typename T>
class WeakPtr;

template<typename T>
class WeakLink : public RefCounted<WeakLink<T>> {
    friend class Weakable<T>;

public:
    T* ptr() { return static_cast<T*>(m_ptr); }
    const T* ptr() const { return static_cast<const T*>(m_ptr); }

private:
    explicit WeakLink(T& weakable)
        : m_ptr(&weakable)
    {
    }
    T* m_ptr;
};

template<typename T>
class Weakable {
private:
    class Link;

public:
    WeakPtr<T> make_weak_ptr();

protected:
    Weakable() {}

    ~Weakable()
    {
        if (m_link)
            m_link->m_ptr = nullptr;
    }

private:
    RefPtr<WeakLink<T>> m_link;
};

}

using AK::Weakable;