313 lines
12 KiB
C++
313 lines
12 KiB
C++
// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
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#pragma once
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/*! \file rx-with_latest_from.hpp
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\brief For each item from the first observable select the latest value from all the observables to emit from the new observable that is returned.
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\tparam AN types of scheduler (optional), aggregate function (optional), and source observables
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\param an scheduler (optional), aggregation function (optional), and source observables
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\return Observable that emits items that are the result of combining the items emitted by the source observables.
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If scheduler is omitted, identity_current_thread is used.
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If aggregation function is omitted, the resulting observable returns tuples of emitted items.
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\sample
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Neither scheduler nor aggregation function are present:
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\snippet with_latest_from.cpp with_latest_from sample
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\snippet output.txt with_latest_from sample
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Only scheduler is present:
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\snippet with_latest_from.cpp Coordination with_latest_from sample
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\snippet output.txt Coordination with_latest_from sample
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Only aggregation function is present:
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\snippet with_latest_from.cpp Selector with_latest_from sample
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\snippet output.txt Selector with_latest_from sample
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Both scheduler and aggregation function are present:
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\snippet with_latest_from.cpp Coordination+Selector with_latest_from sample
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\snippet output.txt Coordination+Selector with_latest_from sample
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*/
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#if !defined(RXCPP_OPERATORS_RX_WITH_LATEST_FROM_HPP)
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#define RXCPP_OPERATORS_RX_WITH_LATEST_FROM_HPP
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#include "../rx-includes.hpp"
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namespace rxcpp {
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namespace operators {
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namespace detail {
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template<class... AN>
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struct with_latest_from_invalid_arguments {};
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template<class... AN>
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struct with_latest_from_invalid : public rxo::operator_base<with_latest_from_invalid_arguments<AN...>> {
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using type = observable<with_latest_from_invalid_arguments<AN...>, with_latest_from_invalid<AN...>>;
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};
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template<class... AN>
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using with_latest_from_invalid_t = typename with_latest_from_invalid<AN...>::type;
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template<class Selector, class... ObservableN>
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struct is_with_latest_from_selector_check {
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typedef rxu::decay_t<Selector> selector_type;
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struct tag_not_valid;
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template<class CS, class... CON>
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static auto check(int) -> decltype((*(CS*)nullptr)((*(typename CON::value_type*)nullptr)...));
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template<class CS, class... CON>
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static tag_not_valid check(...);
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using type = decltype(check<selector_type, rxu::decay_t<ObservableN>...>(0));
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static const bool value = !std::is_same<type, tag_not_valid>::value;
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};
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template<class Selector, class... ObservableN>
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struct invalid_with_latest_from_selector {
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static const bool value = false;
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};
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template<class Selector, class... ObservableN>
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struct is_with_latest_from_selector : public std::conditional<
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is_with_latest_from_selector_check<Selector, ObservableN...>::value,
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is_with_latest_from_selector_check<Selector, ObservableN...>,
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invalid_with_latest_from_selector<Selector, ObservableN...>>::type {
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};
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template<class Selector, class... ON>
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using result_with_latest_from_selector_t = typename is_with_latest_from_selector<Selector, ON...>::type;
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template<class Coordination, class Selector, class... ObservableN>
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struct with_latest_from_traits {
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typedef std::tuple<ObservableN...> tuple_source_type;
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typedef std::tuple<rxu::detail::maybe<typename ObservableN::value_type>...> tuple_source_value_type;
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typedef rxu::decay_t<Selector> selector_type;
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typedef rxu::decay_t<Coordination> coordination_type;
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typedef typename is_with_latest_from_selector<selector_type, ObservableN...>::type value_type;
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};
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template<class Coordination, class Selector, class... ObservableN>
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struct with_latest_from : public operator_base<rxu::value_type_t<with_latest_from_traits<Coordination, Selector, ObservableN...>>>
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{
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typedef with_latest_from<Coordination, Selector, ObservableN...> this_type;
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typedef with_latest_from_traits<Coordination, Selector, ObservableN...> traits;
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typedef typename traits::tuple_source_type tuple_source_type;
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typedef typename traits::tuple_source_value_type tuple_source_value_type;
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typedef typename traits::selector_type selector_type;
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typedef typename traits::coordination_type coordination_type;
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typedef typename coordination_type::coordinator_type coordinator_type;
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struct values
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{
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values(tuple_source_type o, selector_type s, coordination_type sf)
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: source(std::move(o))
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, selector(std::move(s))
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, coordination(std::move(sf))
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{
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}
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tuple_source_type source;
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selector_type selector;
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coordination_type coordination;
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};
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values initial;
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with_latest_from(coordination_type sf, selector_type s, tuple_source_type ts)
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: initial(std::move(ts), std::move(s), std::move(sf))
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{
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}
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template<int Index, class State>
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void subscribe_one(std::shared_ptr<State> state) const {
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typedef typename std::tuple_element<Index, tuple_source_type>::type::value_type source_value_type;
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composite_subscription innercs;
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// when the out observer is unsubscribed all the
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// inner subscriptions are unsubscribed as well
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state->out.add(innercs);
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auto source = on_exception(
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[&](){return state->coordinator.in(std::get<Index>(state->source));},
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state->out);
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if (source.empty()) {
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return;
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}
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// this subscribe does not share the observer subscription
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// so that when it is unsubscribed the observer can be called
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// until the inner subscriptions have finished
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auto sink = make_subscriber<source_value_type>(
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state->out,
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innercs,
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// on_next
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[state](source_value_type st) {
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auto& value = std::get<Index>(state->latest);
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if (value.empty()) {
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++state->valuesSet;
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}
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value.reset(st);
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if (state->valuesSet == sizeof... (ObservableN) && Index == 0) {
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auto values = rxu::surely(state->latest);
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auto selectedResult = rxu::apply(values, state->selector);
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state->out.on_next(selectedResult);
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}
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},
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// on_error
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[state](rxu::error_ptr e) {
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state->out.on_error(e);
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},
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// on_completed
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[state]() {
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if (--state->pendingCompletions == 0) {
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state->out.on_completed();
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}
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}
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);
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auto selectedSink = on_exception(
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[&](){return state->coordinator.out(sink);},
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state->out);
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if (selectedSink.empty()) {
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return;
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}
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source->subscribe(std::move(selectedSink.get()));
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}
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template<class State, int... IndexN>
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void subscribe_all(std::shared_ptr<State> state, rxu::values<int, IndexN...>) const {
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bool subscribed[] = {(subscribe_one<(sizeof...(IndexN)) - 1 - IndexN>(state), true)...};
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subscribed[0] = (*subscribed); // silence warning
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}
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template<class Subscriber>
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void on_subscribe(Subscriber scbr) const {
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static_assert(is_subscriber<Subscriber>::value, "subscribe must be passed a subscriber");
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typedef Subscriber output_type;
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struct with_latest_from_state_type
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: public std::enable_shared_from_this<with_latest_from_state_type>
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, public values
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{
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with_latest_from_state_type(values i, coordinator_type coor, output_type oarg)
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: values(std::move(i))
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, pendingCompletions(sizeof... (ObservableN))
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, valuesSet(0)
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, coordinator(std::move(coor))
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, out(std::move(oarg))
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{
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}
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// on_completed on the output must wait until all the
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// subscriptions have received on_completed
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mutable int pendingCompletions;
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mutable int valuesSet;
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mutable tuple_source_value_type latest;
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coordinator_type coordinator;
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output_type out;
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};
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auto coordinator = initial.coordination.create_coordinator(scbr.get_subscription());
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// take a copy of the values for each subscription
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auto state = std::make_shared<with_latest_from_state_type>(initial, std::move(coordinator), std::move(scbr));
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subscribe_all(state, typename rxu::values_from<int, sizeof...(ObservableN)>::type());
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}
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};
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}
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/*! @copydoc rx-with_latest_from.hpp
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*/
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template<class... AN>
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auto with_latest_from(AN&&... an)
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-> operator_factory<with_latest_from_tag, AN...> {
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return operator_factory<with_latest_from_tag, AN...>(std::make_tuple(std::forward<AN>(an)...));
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}
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}
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template<>
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struct member_overload<with_latest_from_tag>
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{
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template<class Observable, class... ObservableN,
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class Enabled = rxu::enable_if_all_true_type_t<
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all_observables<Observable, ObservableN...>>,
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class with_latest_from = rxo::detail::with_latest_from<identity_one_worker, rxu::detail::pack, rxu::decay_t<Observable>, rxu::decay_t<ObservableN>...>,
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class Value = rxu::value_type_t<with_latest_from>,
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class Result = observable<Value, with_latest_from>>
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static Result member(Observable&& o, ObservableN&&... on)
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{
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return Result(with_latest_from(identity_current_thread(), rxu::pack(), std::make_tuple(std::forward<Observable>(o), std::forward<ObservableN>(on)...)));
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}
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template<class Observable, class Selector, class... ObservableN,
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class Enabled = rxu::enable_if_all_true_type_t<
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operators::detail::is_with_latest_from_selector<Selector, Observable, ObservableN...>,
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all_observables<Observable, ObservableN...>>,
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class ResolvedSelector = rxu::decay_t<Selector>,
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class with_latest_from = rxo::detail::with_latest_from<identity_one_worker, ResolvedSelector, rxu::decay_t<Observable>, rxu::decay_t<ObservableN>...>,
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class Value = rxu::value_type_t<with_latest_from>,
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class Result = observable<Value, with_latest_from>>
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static Result member(Observable&& o, Selector&& s, ObservableN&&... on)
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{
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return Result(with_latest_from(identity_current_thread(), std::forward<Selector>(s), std::make_tuple(std::forward<Observable>(o), std::forward<ObservableN>(on)...)));
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}
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template<class Coordination, class Observable, class... ObservableN,
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class Enabled = rxu::enable_if_all_true_type_t<
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is_coordination<Coordination>,
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all_observables<Observable, ObservableN...>>,
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class with_latest_from = rxo::detail::with_latest_from<Coordination, rxu::detail::pack, rxu::decay_t<Observable>, rxu::decay_t<ObservableN>...>,
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class Value = rxu::value_type_t<with_latest_from>,
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class Result = observable<Value, with_latest_from>>
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static Result member(Observable&& o, Coordination&& cn, ObservableN&&... on)
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{
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return Result(with_latest_from(std::forward<Coordination>(cn), rxu::pack(), std::make_tuple(std::forward<Observable>(o), std::forward<ObservableN>(on)...)));
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}
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template<class Coordination, class Selector, class Observable, class... ObservableN,
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class Enabled = rxu::enable_if_all_true_type_t<
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is_coordination<Coordination>,
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operators::detail::is_with_latest_from_selector<Selector, Observable, ObservableN...>,
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all_observables<Observable, ObservableN...>>,
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class ResolvedSelector = rxu::decay_t<Selector>,
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class with_latest_from = rxo::detail::with_latest_from<Coordination, ResolvedSelector, rxu::decay_t<Observable>, rxu::decay_t<ObservableN>...>,
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class Value = rxu::value_type_t<with_latest_from>,
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class Result = observable<Value, with_latest_from>>
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static Result member(Observable&& o, Coordination&& cn, Selector&& s, ObservableN&&... on)
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{
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return Result(with_latest_from(std::forward<Coordination>(cn), std::forward<Selector>(s), std::make_tuple(std::forward<Observable>(o), std::forward<ObservableN>(on)...)));
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}
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template<class... AN>
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static operators::detail::with_latest_from_invalid_t<AN...> member(const AN&...) {
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std::terminate();
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return {};
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static_assert(sizeof...(AN) == 10000, "with_latest_from takes (optional Coordination, optional Selector, required Observable, optional Observable...), Selector takes (Observable::value_type...)");
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}
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};
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}
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#endif
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