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This API is only used by Jakt to implement weak reference unwrapping. By making it return a NonnullRefPtr, it can be assigned to anything that accepts a NonnullRefPtr, unlike the previous T* return type (since that can also be null).
214 lines
4.6 KiB
C++
214 lines
4.6 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Weakable.h>
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namespace AK {
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template<typename T>
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class [[nodiscard]] WeakPtr {
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template<typename U>
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friend class Weakable;
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public:
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WeakPtr() = default;
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template<SameAs<OptionalNone> V>
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WeakPtr(V) { }
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template<SameAs<OptionalNone> V>
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WeakPtr& operator=(V)
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{
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clear();
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return *this;
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}
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template<typename U>
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WeakPtr(WeakPtr<U> const& other)
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requires(IsBaseOf<T, U>)
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: m_link(other.m_link)
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{
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}
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template<typename U>
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WeakPtr(WeakPtr<U>&& other)
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requires(IsBaseOf<T, U>)
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: m_link(other.take_link())
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{
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}
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template<typename U>
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WeakPtr& operator=(WeakPtr<U>&& other)
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requires(IsBaseOf<T, U>)
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{
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m_link = other.take_link();
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return *this;
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}
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template<typename U>
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WeakPtr& operator=(WeakPtr<U> const& other)
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requires(IsBaseOf<T, U>)
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{
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if ((void const*)this != (void const*)&other)
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m_link = other.m_link;
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return *this;
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}
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WeakPtr& operator=(nullptr_t)
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{
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clear();
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return *this;
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}
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template<typename U>
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WeakPtr(U const& object)
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requires(IsBaseOf<T, U>)
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: m_link(object.template make_weak_ptr<U>().take_link())
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{
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}
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template<typename U>
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WeakPtr(U const* object)
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requires(IsBaseOf<T, U>)
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{
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if (object)
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m_link = object->template make_weak_ptr<U>().take_link();
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}
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template<typename U>
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WeakPtr(RefPtr<U> const& object)
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requires(IsBaseOf<T, U>)
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{
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if (object)
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m_link = object->template make_weak_ptr<U>().take_link();
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}
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template<typename U>
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WeakPtr(NonnullRefPtr<U> const& object)
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requires(IsBaseOf<T, U>)
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{
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m_link = object->template make_weak_ptr<U>().take_link();
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}
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template<typename U>
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WeakPtr& operator=(U const& object)
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requires(IsBaseOf<T, U>)
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{
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m_link = object.template make_weak_ptr<U>().take_link();
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return *this;
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}
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template<typename U>
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WeakPtr& operator=(U const* object)
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requires(IsBaseOf<T, U>)
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{
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if (object)
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m_link = object->template make_weak_ptr<U>().take_link();
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else
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m_link = nullptr;
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return *this;
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}
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template<typename U>
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WeakPtr& operator=(RefPtr<U> const& object)
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requires(IsBaseOf<T, U>)
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{
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if (object)
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m_link = object->template make_weak_ptr<U>().take_link();
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else
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m_link = nullptr;
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return *this;
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}
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template<typename U>
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WeakPtr& operator=(NonnullRefPtr<U> const& object)
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requires(IsBaseOf<T, U>)
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{
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m_link = object->template make_weak_ptr<U>().take_link();
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return *this;
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}
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[[nodiscard]] RefPtr<T> strong_ref() const
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{
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return RefPtr<T> { ptr() };
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}
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T* ptr() const { return unsafe_ptr(); }
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T* operator->() const { return unsafe_ptr(); }
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operator T*() const { return unsafe_ptr(); }
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[[nodiscard]] T* unsafe_ptr() const
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{
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if (m_link)
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return m_link->template unsafe_ptr<T>();
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return nullptr;
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}
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[[nodiscard]] NonnullRefPtr<T> value() const
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{
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VERIFY(has_value());
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return *unsafe_ptr();
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}
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operator bool() const { return m_link ? !m_link->is_null() : false; }
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[[nodiscard]] bool is_null() const { return !m_link || m_link->is_null(); }
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[[nodiscard]] bool has_value() const { return !is_null(); }
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void clear() { m_link = nullptr; }
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[[nodiscard]] RefPtr<WeakLink> take_link() { return move(m_link); }
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private:
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WeakPtr(RefPtr<WeakLink> const& link)
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: m_link(link)
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{
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}
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RefPtr<WeakLink> m_link;
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};
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template<typename T>
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template<typename U>
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inline ErrorOr<WeakPtr<U>> Weakable<T>::try_make_weak_ptr() const
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{
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if (!m_link)
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m_link = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) WeakLink(const_cast<T&>(static_cast<T const&>(*this)))));
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return WeakPtr<U>(m_link);
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}
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template<typename T>
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struct Formatter<WeakPtr<T>> : Formatter<T const*> {
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ErrorOr<void> format(FormatBuilder& builder, WeakPtr<T> const& value)
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{
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return Formatter<T const*>::format(builder, value.ptr());
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}
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};
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template<typename T>
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ErrorOr<WeakPtr<T>> try_make_weak_ptr_if_nonnull(T const* ptr)
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{
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if (ptr) {
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return ptr->template try_make_weak_ptr<T>();
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}
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return WeakPtr<T> {};
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}
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template<typename T>
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WeakPtr<T> make_weak_ptr_if_nonnull(T const* ptr)
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{
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return MUST(try_make_weak_ptr_if_nonnull(ptr));
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}
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}
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#if USING_AK_GLOBALLY
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using AK::WeakPtr;
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#endif
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