84 lines
2.4 KiB
C++
84 lines
2.4 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 Data {
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// This module suggests a way to hold global data structures, that are
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// created on demand and deleted at the end of the app launch.
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//
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// Usage:
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//
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// class MyData : public Data::AbstractStruct { .. data .. };
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// Data::GlobalStructurePointer<MyData> myData;
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// .. somewhere when needed ..
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// myData.createIfNull();
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class AbstractStructure {
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public:
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virtual ~AbstractStructure() = 0;
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};
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inline AbstractStructure::~AbstractStructure() = default;
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namespace internal {
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void registerAbstractStructure(AbstractStructure **p);
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} // namespace
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// Must be created in global scope!
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// Structure is derived from AbstractStructure.
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template <typename Structure>
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class GlobalStructurePointer {
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public:
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GlobalStructurePointer() = default;
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GlobalStructurePointer(const GlobalStructurePointer<Structure> &other) = delete;
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GlobalStructurePointer &operator=(const GlobalStructurePointer<Structure> &other) = delete;
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void createIfNull() {
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if (!_p) {
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_p = new Structure();
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internal::registerAbstractStructure(&_p);
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}
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}
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Structure *operator->() {
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t_assert(_p != nullptr);
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return static_cast<Structure*>(_p);
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}
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const Structure *operator->() const {
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t_assert(_p != nullptr);
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return static_cast<const Structure*>(_p);
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}
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explicit operator bool() const {
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return _p != nullptr;
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}
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private:
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AbstractStructure *_p;
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};
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// This method should be called at the end of the app launch.
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// It will destroy all data structures created by Data::GlobalStructurePointer.
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void clearGlobalStructures();
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} // namespace Data
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