75 lines
1.7 KiB
C++
75 lines
1.7 KiB
C++
/*
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This file is part of Telegram Desktop,
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the official desktop application for the Telegram messaging service.
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For license and copyright information please follow this link:
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https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
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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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class flatten_latest_helper {
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public:
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template <
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typename Value,
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typename Error,
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typename Generator,
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typename MetaGenerator>
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auto operator()(producer<
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producer<Value, Error, Generator>,
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Error,
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MetaGenerator> &&initial) const {
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return make_producer<Value, Error>([
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initial = std::move(initial)
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](const auto &consumer) mutable {
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auto state = consumer.template make_state<State>();
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return std::move(initial).start(
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[consumer, state](producer<Value, Error> &&inner) {
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state->finished = false;
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state->alive = lifetime();
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std::move(inner).start(
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[consumer](auto &&value) {
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consumer.put_next_forward(std::forward<decltype(value)>(value));
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}, [consumer](auto &&error) {
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consumer.put_error_forward(std::forward<decltype(error)>(error));
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}, [consumer, state] {
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if (state->finished) {
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consumer.put_done();
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} else {
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state->finished = true;
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}
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}, state->alive);
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}, [consumer](auto &&error) {
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consumer.put_error_forward(std::forward<decltype(error)>(error));
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}, [consumer, state] {
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if (state->finished) {
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consumer.put_done();
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} else {
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state->finished = true;
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}
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});
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});
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}
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private:
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struct State {
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lifetime alive;
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bool finished = false;
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};
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};
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} // namespace details
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inline auto flatten_latest()
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-> details::flatten_latest_helper {
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return details::flatten_latest_helper();
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}
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} // namespace rpl
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