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tdesktop/Telegram/lib_rpl/rpl/flatten_latest.h
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2026-02-16 15:50:16 +03:00

74 lines
1.7 KiB
C++

// This file is part of Desktop App Toolkit,
// a set of libraries for developing nice desktop applications.
//
// For license and copyright information please follow this link:
// https://github.com/desktop-app/legal/blob/master/LEGAL
//
#pragma once
#include <rpl/producer.h>
namespace rpl {
namespace details {
class flatten_latest_helper {
public:
template <
typename Value,
typename Error,
typename Generator,
typename MetaGenerator>
auto operator()(producer<
producer<Value, Error, Generator>,
Error,
MetaGenerator> &&initial) const {
return make_producer<Value, Error>([
initial = std::move(initial)
](const auto &consumer) mutable {
auto state = consumer.template make_state<State>();
return std::move(initial).start(
[consumer, state](producer<Value, Error> &&inner) {
state->finished = false;
state->alive = lifetime();
std::move(inner).start(
[consumer](auto &&value) {
consumer.put_next_forward(std::forward<decltype(value)>(value));
}, [consumer](auto &&error) {
consumer.put_error_forward(std::forward<decltype(error)>(error));
}, [consumer, state] {
if (state->finished) {
consumer.put_done();
} else {
state->finished = true;
}
}, state->alive);
}, [consumer](auto &&error) {
consumer.put_error_forward(std::forward<decltype(error)>(error));
}, [consumer, state] {
if (state->finished) {
consumer.put_done();
} else {
state->finished = true;
}
});
});
}
private:
struct State {
lifetime alive;
bool finished = false;
};
};
} // namespace details
inline auto flatten_latest()
-> details::flatten_latest_helper {
return details::flatten_latest_helper();
}
} // namespace rpl