ladybird/AK/Weakable.h
Andreas Kling b515ea454f AK: Make sure that Weakable always has the same memory layout
Weakable objects ended up with differing memory layouts in some ports
since they don't build with the DEBUG macro defined.

Instead of forcing ports to define DEBUG, just put this behind a custom
WEAKABLE_DEBUG macro and leave it always-on for now.
2020-02-15 14:49:57 +01:00

88 lines
2.3 KiB
C++

/*
* 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 "Assertions.h"
#include "RefCounted.h"
#include "RefPtr.h"
#define WEAKABLE_DEBUG
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()
{
#ifdef WEAKABLE_DEBUG
m_being_destroyed = true;
#endif
if (m_link)
m_link->m_ptr = nullptr;
}
private:
RefPtr<WeakLink<T>> m_link;
#ifdef WEAKABLE_DEBUG
bool m_being_destroyed { false };
#endif
};
}
using AK::Weakable;