tdesktop/Telegram/SourceFiles/rpl/then.h

86 lines
2.5 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
#include <rpl/producer.h>
namespace rpl {
namespace details {
template <typename Value, typename Error, typename Generator>
class then_helper {
public:
then_helper(producer<Value, Error, Generator> &&following)
: _following(std::move(following)) {
}
template <
typename OtherValue,
typename OtherError,
typename OtherGenerator,
typename NewValue = superset_type_t<Value, OtherValue>,
typename NewError = superset_type_t<Error, OtherError>>
auto operator()(
producer<OtherValue, OtherError, OtherGenerator> &&initial
) {
return make_producer<NewValue, NewError>([
initial = std::move(initial),
following = std::move(_following)
](const auto &consumer) mutable {
return std::move(initial).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,
following = std::move(following)
]() mutable {
consumer.add_lifetime(std::move(following).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] {
consumer.put_done();
}));
});
});
}
private:
producer<Value, Error, Generator> _following;
};
} // namespace details
template <typename Value, typename Error, typename Generator>
inline auto then(producer<Value, Error, Generator> &&following)
-> details::then_helper<Value, Error, Generator> {
return { std::move(following) };
}
} // namespace rpl