tdesktop/Telegram/SourceFiles/data/data_abstract_structure.h

84 lines
2.4 KiB
C++

/*
This file is part of Telegram Desktop,
the official desktop version of Telegram messaging app, see https://telegram.org
Telegram Desktop is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
It is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
In addition, as a special exception, the copyright holders give permission
to link the code of portions of this program with the OpenSSL library.
Full license: https://github.com/telegramdesktop/tdesktop/blob/master/LICENSE
Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
*/
#pragma once
namespace Data {
// This module suggests a way to hold global data structures, that are
// created on demand and deleted at the end of the app launch.
//
// Usage:
//
// class MyData : public Data::AbstractStruct { .. data .. };
// Data::GlobalStructurePointer<MyData> myData;
// .. somewhere when needed ..
// myData.createIfNull();
class AbstractStructure {
public:
virtual ~AbstractStructure() = 0;
};
inline AbstractStructure::~AbstractStructure() = default;
namespace internal {
void registerAbstractStructure(AbstractStructure **p);
} // namespace
// Must be created in global scope!
// Structure is derived from AbstractStructure.
template <typename Structure>
class GlobalStructurePointer {
public:
GlobalStructurePointer() = default;
GlobalStructurePointer(const GlobalStructurePointer<Structure> &other) = delete;
GlobalStructurePointer &operator=(const GlobalStructurePointer<Structure> &other) = delete;
void createIfNull() {
if (!_p) {
_p = new Structure();
internal::registerAbstractStructure(&_p);
}
}
Structure *operator->() {
Assert(_p != nullptr);
return static_cast<Structure*>(_p);
}
const Structure *operator->() const {
Assert(_p != nullptr);
return static_cast<const Structure*>(_p);
}
explicit operator bool() const {
return _p != nullptr;
}
private:
AbstractStructure *_p;
};
// This method should be called at the end of the app launch.
// It will destroy all data structures created by Data::GlobalStructurePointer.
void clearGlobalStructures();
} // namespace Data