108 lines
2.9 KiB
C++
108 lines
2.9 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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#include <rpl/producer.h>
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#include <rpl/event_stream.h>
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namespace rpl {
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template <typename Type>
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class variable {
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public:
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variable() : _data{} {
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}
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variable(const variable &other) = default;
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variable(variable &&other) = default;
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variable &operator=(const variable &other) = default;
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variable &operator=(variable &&other) = default;
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variable(const Type &data) : _data(data) {
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}
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variable(Type &&data) : _data(std::move(data)) {
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}
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variable &operator=(const Type &data) {
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return assign(data);
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}
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template <
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typename OtherType,
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typename = std::enable_if_t<
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std::is_constructible_v<Type, OtherType&&>
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&& !std::is_same_v<std::decay_t<OtherType>, Type>>>
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variable(OtherType &&data) : _data(std::forward<OtherType>(data)) {
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}
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template <
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typename OtherType,
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typename = std::enable_if_t<
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std::is_assignable_v<Type, OtherType&&>
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&& !std::is_same_v<std::decay_t<OtherType>, Type>>>
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variable &operator=(OtherType &&data) {
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return assign(std::forward<OtherType>(data));
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}
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template <
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typename OtherType,
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typename = std::enable_if_t<
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std::is_assignable_v<Type, OtherType>>>
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variable(rpl::producer<OtherType> &&stream) {
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std::move(stream)
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| start([this](auto &&data) {
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*this = std::forward<decltype(data)>(data);
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}, _lifetime);
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}
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template <
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typename OtherType,
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typename = std::enable_if_t<
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std::is_assignable_v<Type, OtherType>>>
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variable &operator=(rpl::producer<OtherType> &&stream) {
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_lifetime.destroy();
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std::move(stream)
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| start([this](auto &&data) {
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*this = std::forward<decltype(data)>(data);
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}, _lifetime);
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}
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Type current() const {
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return _data;
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}
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rpl::producer<Type> value() const {
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return _changes.events_starting_with_copy(_data);
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}
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private:
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template <typename OtherType>
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variable &assign(OtherType &&data) {
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_lifetime.destroy();
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_data = std::forward<OtherType>(data);
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_changes.fire_copy(_data);
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return *this;
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}
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Type _data;
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rpl::event_stream<Type> _changes;
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rpl::lifetime _lifetime;
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};
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} // namespace rpl
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