158 lines
4.0 KiB
C++
158 lines
4.0 KiB
C++
/*
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This file is part of Telegram Desktop,
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the official desktop version of Telegram messaging app, see https://telegram.org
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Telegram Desktop is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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It is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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In addition, as a special exception, the copyright holders give permission
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to link the code of portions of this program with the OpenSSL library.
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Full license: https://github.com/telegramdesktop/tdesktop/blob/master/LICENSE
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Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
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*/
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#pragma once
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#include <rpl/producer.h>
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#include <rpl/combine.h>
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#include <rpl/mappers.h>
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#include "base/optional.h"
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namespace rpl {
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namespace details {
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template <typename Predicate>
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class filter_helper {
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public:
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template <typename OtherPredicate>
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filter_helper(OtherPredicate &&predicate)
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: _predicate(std::forward<OtherPredicate>(predicate)) {
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}
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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 = std::enable_if_t<
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details::is_callable_v<Predicate, Value>>>
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auto operator()(producer<Value, Error, Generator> &&initial) {
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return make_producer<Value, Error>([
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initial = std::move(initial),
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predicate = std::move(_predicate)
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](const auto &consumer) mutable {
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return std::move(initial).start(
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[
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consumer,
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predicate = std::move(predicate)
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](auto &&value) {
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const auto &immutable = value;
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if (details::callable_invoke(
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predicate,
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immutable)
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) {
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consumer.put_next_forward(
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std::forward<decltype(value)>(value));
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}
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}, [consumer](auto &&error) {
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consumer.put_error_forward(
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std::forward<decltype(error)>(error));
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}, [consumer] {
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consumer.put_done();
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});
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});
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}
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private:
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Predicate _predicate;
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};
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} // namespace details
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template <typename Predicate>
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inline auto filter(Predicate &&predicate)
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-> details::filter_helper<std::decay_t<Predicate>> {
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return details::filter_helper<std::decay_t<Predicate>>(
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std::forward<Predicate>(predicate));
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}
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namespace details {
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template <typename FilterError, typename FilterGenerator>
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class filter_helper<producer<bool, FilterError, FilterGenerator>> {
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public:
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filter_helper(
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producer<bool, FilterError, FilterGenerator> &&filterer)
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: _filterer(std::move(filterer)) {
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}
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template <typename Value, typename Error, typename Generator>
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auto operator()(producer<Value, Error, Generator> &&initial) {
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using namespace mappers;
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return combine(std::move(initial), std::move(_filterer))
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| filter(_2)
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| map(_1_of_two);
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}
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private:
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producer<bool, FilterError, FilterGenerator> _filterer;
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};
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template <typename Value>
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inline const Value &deref_optional_helper(
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const base::optional<Value> &value) {
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return *value;
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}
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template <typename Value>
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inline Value &&deref_optional_helper(
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base::optional<Value> &&value) {
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return std::move(*value);
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}
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class filter_optional_helper {
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public:
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template <typename Value, typename Error, typename Generator>
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auto operator()(producer<
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base::optional<Value>,
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Error,
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Generator> &&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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return std::move(initial).start(
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[consumer](auto &&value) {
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if (value) {
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consumer.put_next_forward(
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deref_optional_helper(
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std::forward<decltype(value)>(
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value)));
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}
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}, [consumer](auto &&error) {
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consumer.put_error_forward(
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std::forward<decltype(error)>(error));
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}, [consumer] {
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consumer.put_done();
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});
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});
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}
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};
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} // namespace details
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inline auto filter_optional()
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-> details::filter_optional_helper {
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return details::filter_optional_helper();
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}
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} // namespace rpl
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