tdesktop/Telegram/SourceFiles/rpl/producer.h

/*
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 "base/lambda.h"
#include <rpl/consumer.h>
#include <rpl/lifetime.h>

namespace rpl {
namespace details {

template <typename Lambda>
class mutable_lambda_wrap {
public:
	mutable_lambda_wrap(Lambda &&lambda)
		: _lambda(std::move(lambda)) {
	}

	template <typename... Args>
	auto operator()(Args&&... args) const {
		return (const_cast<mutable_lambda_wrap*>(this)->_lambda)(
			std::forward<Args>(args)...);
	}

private:
	Lambda _lambda;

};

// Type-erased copyable mutable lambda using base::lambda.
template <typename Function> class mutable_lambda;

template <typename Return, typename ...Args>
class mutable_lambda<Return(Args...)> {
public:

	// Copy / move construct / assign from an arbitrary type.
	template <
		typename Lambda,
		typename = std::enable_if_t<std::is_convertible<
			decltype(std::declval<Lambda>()(std::declval<Args>()...)),
			Return
		>::value>>
	mutable_lambda(Lambda other) : _implementation(mutable_lambda_wrap<Lambda>(std::move(other))) {
	}

	template <
		typename ...OtherArgs,
		typename = std::enable_if_t<(sizeof...(Args) == sizeof...(OtherArgs))>>
	Return operator()(OtherArgs&&... args) {
		return _implementation(std::forward<OtherArgs>(args)...);
	}

private:
	base::lambda<Return(Args...)> _implementation;

};

} // namespace details

template <typename Value = empty_value, typename Error = no_error>
class producer {
public:
	using value_type = Value;
	using error_type = Error;
	using consumer_type = consumer<Value, Error>;

	template <typename Generator, typename = std::enable_if<std::is_convertible<
		decltype(std::declval<Generator>()(std::declval<consumer_type>())),
		lifetime
	>::value>>
	producer(Generator &&generator);

	template <
		typename OnNext,
		typename OnError,
		typename OnDone,
		typename = decltype(std::declval<OnNext>()(std::declval<Value>())),
		typename = decltype(std::declval<OnError>()(std::declval<Error>())),
		typename = decltype(std::declval<OnDone>()())>
	lifetime start(
		OnNext &&next,
		OnError &&error,
		OnDone &&done) &&;

	template <
		typename OnNext,
		typename OnError,
		typename OnDone,
		typename = decltype(std::declval<OnNext>()(std::declval<Value>())),
		typename = decltype(std::declval<OnError>()(std::declval<Error>())),
		typename = decltype(std::declval<OnDone>()())>
	lifetime start_copy(
		OnNext &&next,
		OnError &&error,
		OnDone &&done) const &;

	lifetime start_existing(const consumer_type &consumer) &&;

private:
	details::mutable_lambda<
		lifetime(const consumer_type &)> _generator;

};

template <typename Value, typename Error>
template <typename Generator, typename>
producer<Value, Error>::producer(Generator &&generator)
	: _generator(std::forward<Generator>(generator)) {
}

template <typename Value, typename Error>
template <
	typename OnNext,
	typename OnError,
	typename OnDone,
	typename,
	typename,
	typename>
lifetime producer<Value, Error>::start(
		OnNext &&next,
		OnError &&error,
		OnDone &&done) && {
	return std::move(*this).start_existing(consumer<Value, Error>(
		std::forward<OnNext>(next),
		std::forward<OnError>(error),
		std::forward<OnDone>(done)));
}

template <typename Value, typename Error>
template <
	typename OnNext,
	typename OnError,
	typename OnDone,
	typename,
	typename,
	typename>
lifetime producer<Value, Error>::start_copy(
		OnNext &&next,
		OnError &&error,
		OnDone &&done) const & {
	auto copy = *this;
	return std::move(copy).start(
		std::forward<OnNext>(next),
		std::forward<OnError>(error),
		std::forward<OnDone>(done));
}

template <typename Value, typename Error>
lifetime producer<Value, Error>::start_existing(
		const consumer_type &consumer) && {
	consumer.add_lifetime(std::move(_generator)(consumer));
	return [consumer] { consumer.terminate(); };
}

template <typename Value, typename Error>
inline producer<Value, Error> duplicate(const producer<Value, Error> &producer) {
	return producer;
}

template <
	typename Value,
	typename Error,
	typename Method,
	typename = decltype(std::declval<Method>()(std::declval<producer<Value, Error>>()))>
inline auto operator|(producer<Value, Error> &&producer, Method &&method) {
	return std::forward<Method>(method)(std::move(producer));
}

template <typename OnNext>
inline auto bind_on_next(OnNext &&handler) {
	return [handler = std::forward<OnNext>(handler)](auto &&existing) mutable {
		using value_type = typename std::decay_t<decltype(existing)>::value_type;
		using error_type = typename std::decay_t<decltype(existing)>::error_type;
		return producer<no_value, error_type>([
			existing = std::move(existing),
			handler = std::move(handler)
		](const consumer<no_value, error_type> &consumer) mutable {
			return std::move(existing).start(
			[handler = std::move(handler)](value_type &&value) {
				handler(std::move(value));
			}, [consumer](error_type &&error) {
				consumer.put_error(std::move(error));
			}, [consumer] {
				consumer.put_done();
			});
		});
	};
}

template <typename OnError>
inline auto bind_on_error(OnError &&handler) {
	return [handler = std::forward<OnError>(handler)](auto &&existing) mutable {
		using value_type = typename std::decay_t<decltype(existing)>::value_type;
		using error_type = typename std::decay_t<decltype(existing)>::error_type;
		return producer<value_type, no_error>([
			existing = std::move(existing),
			handler = std::move(handler)
		](const consumer<value_type, no_error> &consumer) mutable {
			return std::move(existing).start(
			[consumer](value_type &&value) {
				consumer.put_next(std::move(value));
			}, [handler = std::move(handler)](error_type &&error) {
				handler(std::move(error));
			}, [consumer] {
				consumer.put_done();
			});
		});
	};
}

template <typename OnDone>
inline auto bind_on_done(OnDone &&handler) {
	return [handler = std::forward<OnDone>(handler)](auto &&existing) mutable {
		using value_type = typename std::decay_t<decltype(existing)>::value_type;
		using error_type = typename std::decay_t<decltype(existing)>::error_type;
		return producer<value_type, error_type>([
			existing = std::move(existing),
			handler = std::move(handler)
		](const consumer<value_type, error_type> &consumer) mutable {
			return std::move(existing).start(
			[consumer](value_type &&value) {
				consumer.put_next(std::move(value));
			}, [consumer](error_type &&value) {
				consumer.put_error(std::move(value));
			}, [handler = std::move(handler)] {
				handler();
			});
		});
	};
}

namespace details {

template <typename OnNext>
struct next_holder {
	OnNext next;
};

template <typename OnError>
struct error_holder {
	OnError error;
};

template <typename OnDone>
struct done_holder {
	OnDone done;
};

template <
	typename Value,
	typename Error,
	typename OnNext>
struct producer_with_next {
	producer<Value, Error> producer;
	OnNext next;
};

template <
	typename Value,
	typename Error,
	typename OnError>
struct producer_with_error {
	producer<Value, Error> producer;
	OnError error;
};

template <
	typename Value,
	typename Error,
	typename OnDone>
struct producer_with_done {
	producer<Value, Error> producer;
	OnDone done;
};

template <
	typename Value,
	typename Error,
	typename OnNext,
	typename OnError>
struct producer_with_next_error {
	producer<Value, Error> producer;
	OnNext next;
	OnError error;
};

template <
	typename Value,
	typename Error,
	typename OnNext,
	typename OnDone>
struct producer_with_next_done {
	producer<Value, Error> producer;
	OnNext next;
	OnDone done;
};

template <
	typename Value,
	typename Error,
	typename OnError,
	typename OnDone>
struct producer_with_error_done {
	producer<Value, Error> producer;
	OnError error;
	OnDone done;
};

template <
	typename Value,
	typename Error,
	typename OnNext,
	typename OnError,
	typename OnDone>
struct producer_with_next_error_done {
	producer<Value, Error> producer;
	OnNext next;
	OnError error;
	OnDone done;
};

struct lifetime_holder {
	lifetime &alive_while;
};

} // namespace details

template <typename OnNext>
inline details::next_holder<std::decay_t<OnNext>> on_next(OnNext &&handler) {
	return { std::forward<OnNext>(handler) };
}

template <typename OnError>
inline details::error_holder<std::decay_t<OnError>> on_error(OnError &&handler) {
	return { std::forward<OnError>(handler) };
}

template <typename OnDone>
inline details::done_holder<std::decay_t<OnDone>> on_done(OnDone &&handler) {
	return { std::forward<OnDone>(handler) };
}

inline details::lifetime_holder start(lifetime &alive_while) {
	return { alive_while };
}

namespace details {

template <
	typename Value,
	typename Error,
	typename OnNext,
	typename = decltype(std::declval<OnNext>()(std::declval<Value>()))>
inline producer_with_next<Value, Error, OnNext> operator|(
		producer<Value, Error> &&producer,
		next_holder<OnNext> &&handler) {
	return { std::move(producer), std::move(handler.next) };
}

template <
	typename Value,
	typename Error,
	typename OnError,
	typename = decltype(std::declval<OnError>()(std::declval<Error>()))>
inline producer_with_error<Value, Error, OnError> operator|(
		producer<Value, Error> &&producer,
		error_holder<OnError> &&handler) {
	return { std::move(producer), std::move(handler.error) };
}

template <
	typename Value,
	typename Error,
	typename OnDone,
	typename = decltype(std::declval<OnDone>()())>
inline producer_with_done<Value, Error, OnDone> operator|(
		producer<Value, Error> &&producer,
		done_holder<OnDone> &&handler) {
	return { std::move(producer), std::move(handler.done) };
}

template <
	typename Value,
	typename Error,
	typename OnNext,
	typename OnError,
	typename = decltype(std::declval<OnNext>()(std::declval<Value>())),
	typename = decltype(std::declval<OnError>()(std::declval<Error>()))>
inline producer_with_next_error<Value, Error, OnNext, OnError> operator|(
		producer_with_next<Value, Error, OnNext> &&producer_with_next,
		error_holder<OnError> &&handler) {
	return {
		std::move(producer_with_next.producer),
		std::move(producer_with_next.next),
		std::move(handler.error) };
}

template <
	typename Value,
	typename Error,
	typename OnNext,
	typename OnError,
	typename = decltype(std::declval<OnNext>()(std::declval<Value>())),
	typename = decltype(std::declval<OnError>()(std::declval<Error>()))>
inline producer_with_next_error<Value, Error, OnNext, OnError> operator|(
		producer_with_error<Value, Error, OnError> &&producer_with_error,
		next_holder<OnNext> &&handler) {
	return {
		std::move(producer_with_error.producer),
		std::move(handler.next),
		std::move(producer_with_error.error) };
}

template <
	typename Value,
	typename Error,
	typename OnNext,
	typename OnDone,
	typename = decltype(std::declval<OnNext>()(std::declval<Value>())),
	typename = decltype(std::declval<OnDone>()())>
inline producer_with_next_done<Value, Error, OnNext, OnDone> operator|(
		producer_with_next<Value, Error, OnNext> &&producer_with_next,
		done_holder<OnDone> &&handler) {
	return {
		std::move(producer_with_next.producer),
		std::move(producer_with_next.next),
		std::move(handler.done) };
}

template <
	typename Value,
	typename Error,
	typename OnNext,
	typename OnDone,
	typename = decltype(std::declval<OnNext>()(std::declval<Value>())),
	typename = decltype(std::declval<OnDone>()())>
inline producer_with_next_done<Value, Error, OnNext, OnDone> operator|(
		producer_with_done<Value, Error, OnDone> &&producer_with_done,
		next_holder<OnNext> &&handler) {
	return {
		std::move(producer_with_done.producer),
		std::move(handler.next),
		std::move(producer_with_done.done) };
}

template <
	typename Value,
	typename Error,
	typename OnError,
	typename OnDone,
	typename = decltype(std::declval<OnError>()(std::declval<Error>())),
	typename = decltype(std::declval<OnDone>()())>
inline producer_with_error_done<Value, Error, OnError, OnDone> operator|(
		producer_with_error<Value, Error, OnError> &&producer_with_error,
		done_holder<OnDone> &&handler) {
	return {
		std::move(producer_with_error.producer),
		std::move(producer_with_error.error),
		std::move(handler.done) };
}

template <
	typename Value,
	typename Error,
	typename OnError,
	typename OnDone,
	typename = decltype(std::declval<OnError>()(std::declval<Error>())),
	typename = decltype(std::declval<OnDone>()())>
inline producer_with_error_done<Value, Error, OnError, OnDone> operator|(
		producer_with_done<Value, Error, OnDone> &&producer_with_done,
		error_holder<OnError> &&handler) {
	return {
		std::move(producer_with_done.producer),
		std::move(handler.error),
		std::move(producer_with_done.done) };
}

template <
	typename Value,
	typename Error,
	typename OnNext,
	typename OnError,
	typename OnDone,
	typename = decltype(std::declval<OnNext>()(std::declval<Value>())),
	typename = decltype(std::declval<OnError>()(std::declval<Error>())),
	typename = decltype(std::declval<OnDone>()())>
inline producer_with_next_error_done<
	Value,
	Error,
	OnNext,
	OnError,
	OnDone> operator|(
		producer_with_next_error<
			Value,
			Error,
			OnNext,
			OnError> &&producer_with_next_error,
		done_holder<OnDone> &&handler) {
	return {
		std::move(producer_with_next_error.producer),
		std::move(producer_with_next_error.next),
		std::move(producer_with_next_error.error),
		std::move(handler.done) };
}

template <
	typename Value,
	typename Error,
	typename OnNext,
	typename OnError,
	typename OnDone,
	typename = decltype(std::declval<OnNext>()(std::declval<Value>())),
	typename = decltype(std::declval<OnError>()(std::declval<Error>())),
	typename = decltype(std::declval<OnDone>()())>
inline producer_with_next_error_done<
	Value,
	Error,
	OnNext,
	OnError,
	OnDone> operator|(
		producer_with_next_done<
			Value,
			Error,
			OnNext,
			OnDone> &&producer_with_next_done,
		error_holder<OnError> &&handler) {
	return {
		std::move(producer_with_next_done.producer),
		std::move(producer_with_next_done.next),
		std::move(handler.error),
		std::move(producer_with_next_done.done) };
}

template <
	typename Value,
	typename Error,
	typename OnNext,
	typename OnError,
	typename OnDone,
	typename = decltype(std::declval<OnNext>()(std::declval<Value>())),
	typename = decltype(std::declval<OnError>()(std::declval<Error>())),
	typename = decltype(std::declval<OnDone>()())>
inline producer_with_next_error_done<
	Value,
	Error,
	OnNext,
	OnError,
	OnDone> operator|(
		producer_with_error_done<
			Value,
			Error,
			OnError,
			OnDone> &&producer_with_error_done,
		next_holder<OnNext> &&handler) {
	return {
		std::move(producer_with_error_done.producer),
		std::move(handler.next),
		std::move(producer_with_error_done.error),
		std::move(producer_with_error_done.done) };
}

template <
	typename Value,
	typename Error,
	typename OnNext,
	typename OnError,
	typename OnDone>
inline void operator|(
		producer_with_next_error_done<
			Value,
			Error,
			OnNext,
			OnError,
			OnDone> &&producer_with_next_error_done,
		lifetime_holder &&lifetime) {
	lifetime.alive_while.add(
		std::move(producer_with_next_error_done.producer).start(
			std::move(producer_with_next_error_done.next),
			std::move(producer_with_next_error_done.error),
			std::move(producer_with_next_error_done.done)));
}

template <typename Value, typename Error>
inline void operator|(
		producer<Value, Error> &&producer,
		lifetime_holder &&start_with_lifetime) {
	return std::move(producer)
		| on_next([](Value&&) {})
		| on_error([](Error&&) {})
		| on_done([] {})
		| std::move(start_with_lifetime);
}

template <typename Value, typename Error, typename OnNext>
inline void operator|(
		producer_with_next<Value, Error, OnNext> &&producer_with_next,
		lifetime_holder &&start_with_lifetime) {
	return std::move(producer_with_next)
		| on_error([](Error&&) {})
		| on_done([] {})
		| std::move(start_with_lifetime);
}

template <typename Value, typename Error, typename OnError>
inline void operator|(
		producer_with_error<Value, Error, OnError> &&producer_with_error,
		lifetime_holder &&start_with_lifetime) {
	return std::move(producer_with_error)
		| on_next([](Value&&) {})
		| on_done([] {})
		| std::move(start_with_lifetime);
}

template <typename Value, typename Error, typename OnDone>
inline void operator|(
		producer_with_done<Value, Error, OnDone> &&producer_with_done,
		lifetime_holder &&start_with_lifetime) {
	return std::move(producer_with_done)
		| on_next([](Value&&) {})
		| on_error([](Error&&) {})
		| std::move(start_with_lifetime);
}

template <typename Value, typename Error, typename OnNext, typename OnError>
inline void operator|(
		producer_with_next_error<
			Value,
			Error,
			OnNext,
			OnError> &&producer_with_next_error,
		lifetime_holder &&start_with_lifetime) {
	return std::move(producer_with_next_error)
		| on_done([] {})
		| std::move(start_with_lifetime);
}

template <typename Value, typename Error, typename OnNext, typename OnDone>
inline void operator|(
		producer_with_next_done<
			Value,
			Error,
			OnNext,
			OnDone> &&producer_with_next_done,
		lifetime_holder &&start_with_lifetime) {
	return std::move(producer_with_next_done)
		| on_error([](Error&&) {})
		| std::move(start_with_lifetime);
}

template <typename Value, typename Error, typename OnError, typename OnDone>
inline void operator|(
		producer_with_error_done<
			Value,
			Error,
			OnError,
			OnDone> &&producer_with_error_done,
		lifetime_holder &&start_with_lifetime) {
	return std::move(producer_with_error_done)
		| on_next([](Value&&) {})
		| std::move(start_with_lifetime);
}

} // namespace details
} // namespace rpl