ladybird/AK/WeakPtr.h

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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
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#pragma once
#include <AK/Weakable.h>
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namespace AK {
template<typename T>
class [[nodiscard]] WeakPtr {
template<typename U>
friend class Weakable;
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public:
WeakPtr() = default;
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template<SameAs<OptionalNone> V>
WeakPtr(V) { }
template<SameAs<OptionalNone> V>
WeakPtr& operator=(V)
{
clear();
return *this;
}
template<typename U>
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WeakPtr(WeakPtr<U> const& other)
requires(IsBaseOf<T, U>)
: m_link(other.m_link)
{
}
template<typename U>
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WeakPtr(WeakPtr<U>&& other)
requires(IsBaseOf<T, U>)
: m_link(other.take_link())
{
}
template<typename U>
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WeakPtr& operator=(WeakPtr<U>&& other)
requires(IsBaseOf<T, U>)
{
m_link = other.take_link();
return *this;
}
template<typename U>
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WeakPtr& operator=(WeakPtr<U> const& other)
requires(IsBaseOf<T, U>)
{
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if ((void const*)this != (void const*)&other)
m_link = other.m_link;
return *this;
}
WeakPtr& operator=(nullptr_t)
{
clear();
return *this;
}
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template<typename U>
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WeakPtr(U const& object)
requires(IsBaseOf<T, U>)
: m_link(object.template make_weak_ptr<U>().take_link())
{
}
template<typename U>
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WeakPtr(U const* object)
requires(IsBaseOf<T, U>)
{
if (object)
m_link = object->template make_weak_ptr<U>().take_link();
}
template<typename U>
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WeakPtr(RefPtr<U> const& object)
requires(IsBaseOf<T, U>)
{
if (object)
m_link = object->template make_weak_ptr<U>().take_link();
}
template<typename U>
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WeakPtr(NonnullRefPtr<U> const& object)
requires(IsBaseOf<T, U>)
{
m_link = object->template make_weak_ptr<U>().take_link();
}
template<typename U>
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WeakPtr& operator=(U const& object)
requires(IsBaseOf<T, U>)
{
m_link = object.template make_weak_ptr<U>().take_link();
return *this;
}
template<typename U>
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WeakPtr& operator=(U const* object)
requires(IsBaseOf<T, U>)
{
if (object)
m_link = object->template make_weak_ptr<U>().take_link();
else
m_link = nullptr;
return *this;
}
template<typename U>
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WeakPtr& operator=(RefPtr<U> const& object)
requires(IsBaseOf<T, U>)
{
if (object)
m_link = object->template make_weak_ptr<U>().take_link();
else
m_link = nullptr;
return *this;
}
template<typename U>
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WeakPtr& operator=(NonnullRefPtr<U> const& object)
requires(IsBaseOf<T, U>)
{
m_link = object->template make_weak_ptr<U>().take_link();
return *this;
}
[[nodiscard]] RefPtr<T> strong_ref() const
{
return RefPtr<T> { ptr() };
}
T* ptr() const { return unsafe_ptr(); }
T* operator->() const { return unsafe_ptr(); }
operator T*() const { return unsafe_ptr(); }
[[nodiscard]] T* unsafe_ptr() const
{
if (m_link)
return m_link->template unsafe_ptr<T>();
return nullptr;
}
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[[nodiscard]] NonnullRefPtr<T> value() const
{
VERIFY(has_value());
return *unsafe_ptr();
}
operator bool() const { return m_link ? !m_link->is_null() : false; }
[[nodiscard]] bool is_null() const { return !m_link || m_link->is_null(); }
[[nodiscard]] bool has_value() const { return !is_null(); }
void clear() { m_link = nullptr; }
[[nodiscard]] RefPtr<WeakLink> take_link() { return move(m_link); }
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private:
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WeakPtr(RefPtr<WeakLink> const& link)
: m_link(link)
{
}
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RefPtr<WeakLink> m_link;
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};
template<typename T>
template<typename U>
inline ErrorOr<WeakPtr<U>> Weakable<T>::try_make_weak_ptr() const
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{
if (!m_link)
m_link = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) WeakLink(const_cast<T&>(static_cast<T const&>(*this)))));
return WeakPtr<U>(m_link);
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}
template<typename T>
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struct Formatter<WeakPtr<T>> : Formatter<T const*> {
ErrorOr<void> format(FormatBuilder& builder, WeakPtr<T> const& value)
{
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return Formatter<T const*>::format(builder, value.ptr());
}
};
template<typename T>
ErrorOr<WeakPtr<T>> try_make_weak_ptr_if_nonnull(T const* ptr)
{
if (ptr) {
return ptr->template try_make_weak_ptr<T>();
}
return WeakPtr<T> {};
}
template<typename T>
WeakPtr<T> make_weak_ptr_if_nonnull(T const* ptr)
{
return MUST(try_make_weak_ptr_if_nonnull(ptr));
}
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}
#if USING_AK_GLOBALLY
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using AK::WeakPtr;
#endif