6003ac2132
Sometimes you don't need shared ownership (shared_ptr), but you still need to be able to have weak pointers to an object. Now you can derive the object from base::enable_weak_from_this and use base::weak_unique_ptr<T> after that.
88 lines
2.5 KiB
C++
88 lines
2.5 KiB
C++
/*
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This file is part of Telegram Desktop,
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the official desktop version of Telegram messaging app, see https://telegram.org
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Telegram Desktop is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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It is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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In addition, as a special exception, the copyright holders give permission
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to link the code of portions of this program with the OpenSSL library.
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Full license: https://github.com/telegramdesktop/tdesktop/blob/master/LICENSE
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Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
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*/
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#pragma once
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namespace base {
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class enable_weak_from_this;
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template <typename T, typename = std::enable_if_t<std::is_base_of<enable_weak_from_this, T>::value>>
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class weak_unique_ptr;
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class enable_weak_from_this {
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public:
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enable_weak_from_this() = default;
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enable_weak_from_this(const enable_weak_from_this &other) noexcept {
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}
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enable_weak_from_this(enable_weak_from_this &&other) noexcept {
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}
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enable_weak_from_this &operator=(const enable_weak_from_this &other) noexcept {
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return *this;
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}
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enable_weak_from_this &operator=(enable_weak_from_this &&other) noexcept {
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return *this;
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}
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private:
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template <typename Child, typename>
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friend class weak_unique_ptr;
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std::shared_ptr<enable_weak_from_this*> getGuarded() {
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if (!_guarded) {
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_guarded = std::make_shared<enable_weak_from_this*>(this);
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}
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return _guarded;
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}
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std::shared_ptr<enable_weak_from_this*> _guarded;
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};
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template <typename T, typename>
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class weak_unique_ptr {
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public:
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weak_unique_ptr() = default;
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weak_unique_ptr(T *value) : _guarded(value ? value->getGuarded() : std::shared_ptr<enable_weak_from_this*>()) {
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}
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weak_unique_ptr(const std::unique_ptr<T> &value) : _guarded(value ? value->getGuarded() : std::shared_ptr<enable_weak_from_this*>()) {
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}
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T *get() const noexcept {
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if (auto shared = _guarded.lock()) {
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return static_cast<T*>(*shared);
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}
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return nullptr;
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}
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explicit operator bool() const noexcept {
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return !!_guarded.lock();
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}
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T &operator*() const noexcept {
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return *get();
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}
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T *operator->() const noexcept {
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return get();
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}
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private:
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std::weak_ptr<enable_weak_from_this*> _guarded;
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};
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} // namespace base
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