tdesktop/Telegram/SourceFiles/rpl/map.h

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2017-09-12 16:58:14 +03:00
/*
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 Transform>
class map_helper {
public:
template <typename OtherTransform>
map_helper(OtherTransform &&transform)
: _transform(std::forward<OtherTransform>(transform)) {
}
template <
typename Value,
typename Error,
typename NewValue = decltype(
std::declval<Transform>()(std::declval<Value>())
)>
rpl::producer<NewValue, Error> operator()(
rpl::producer<Value, Error> &&initial) {
return [
initial = std::move(initial),
transform = std::move(_transform)
](const consumer<NewValue, Error> &consumer) mutable {
return std::move(initial).start(
[
consumer,
transform = std::move(transform)
](Value &&value) {
consumer.put_next(transform(std::move(value)));
}, [consumer](Error &&error) {
consumer.put_error(std::move(error));
}, [consumer] {
consumer.put_done();
});
};
}
private:
Transform _transform;
};
} // namespace details
template <typename Transform>
auto map(Transform &&transform)
-> details::map_helper<std::decay_t<Transform>> {
return details::map_helper<std::decay_t<Transform>>(
std::forward<Transform>(transform));
}
} // namespace rpl