163 lines
4.2 KiB
C++
163 lines
4.2 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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namespace rpl {
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namespace details {
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struct merge_state {
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merge_state(int working) : working(working) {
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}
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int working = 0;
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};
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template <size_t Index, typename consumer_type>
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class merge_subscribe_one {
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public:
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merge_subscribe_one(
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const consumer_type &consumer,
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merge_state *state)
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: _consumer(consumer)
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, _state(state) {
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}
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template <typename Value, typename Error, typename Generator>
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void subscribe(producer<Value, Error, Generator> &&producer) {
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_consumer.add_lifetime(std::move(producer).start(
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[consumer = _consumer](auto &&value) {
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consumer.put_next_forward(
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std::forward<decltype(value)>(value));
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}, [consumer = _consumer](auto &&error) {
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consumer.put_error_forward(
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std::forward<decltype(error)>(error));
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}, [consumer = _consumer, state = _state] {
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if (!--state->working) {
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consumer.put_done();
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}
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}));
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}
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private:
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const consumer_type &_consumer;
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merge_state *_state = nullptr;
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};
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template <
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typename consumer_type,
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typename Value,
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typename Error,
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typename ...Generators,
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std::size_t ...I>
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inline void merge_subscribe(
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const consumer_type &consumer,
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merge_state *state,
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std::index_sequence<I...>,
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std::tuple<producer<Value, Error, Generators>...> &&saved) {
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auto consume = { (
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details::merge_subscribe_one<I, consumer_type>(
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consumer,
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state
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).subscribe(std::get<I>(std::move(saved))), 0)... };
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(void)consume;
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}
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template <typename ...Producers>
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class merge_implementation_helper;
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template <typename ...Producers>
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merge_implementation_helper<std::decay_t<Producers>...>
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make_merge_implementation_helper(Producers &&...producers) {
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return merge_implementation_helper<std::decay_t<Producers>...>(
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std::forward<Producers>(producers)...);
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}
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template <
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typename Value,
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typename Error,
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typename ...Generators>
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class merge_implementation_helper<producer<Value, Error, Generators>...> {
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public:
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merge_implementation_helper(
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producer<Value, Error, Generators> &&...producers)
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: _saved(std::make_tuple(std::move(producers)...)) {
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}
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template <typename Handlers>
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lifetime operator()(const consumer<Value, Error, Handlers> &consumer) {
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auto state = consumer.template make_state<
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details::merge_state>(sizeof...(Generators));
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constexpr auto kArity = sizeof...(Generators);
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details::merge_subscribe(
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consumer,
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state,
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std::make_index_sequence<kArity>(),
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std::move(_saved));
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return lifetime();
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}
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private:
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std::tuple<producer<Value, Error, Generators>...> _saved;
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};
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template <
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typename Value,
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typename Error,
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typename ...Generators>
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inline auto merge_implementation(
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producer<Value, Error, Generators> &&...producers) {
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return make_producer<Value, Error>(
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make_merge_implementation_helper(std::move(producers)...));
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}
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template <typename ...Args>
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struct merge_producers : std::false_type {
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};
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template <typename ...Args>
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constexpr bool merge_producers_v
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= merge_producers<Args...>::value;
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template <
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typename Value,
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typename Error,
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typename ...Generators>
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struct merge_producers<
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producer<Value, Error, Generators>...>
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: std::true_type {
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};
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} // namespace details
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template <
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typename ...Args,
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typename = std::enable_if_t<
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details::merge_producers_v<Args...>>>
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inline decltype(auto) merge(Args &&...args) {
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return details::merge_implementation(std::move(args)...);
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}
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} // namespace rpl
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