299 lines
11 KiB
C++
299 lines
11 KiB
C++
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// 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-amb.hpp
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\brief For each item from only the first of the given observables deliver from the new observable that is returned, on the specified scheduler.
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There are 2 variants of the operator:
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- The source observable emits nested observables, one of the nested observables is selected.
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- The source observable and the arguments v0...vn are used to provide the observables to select from.
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\tparam Coordination the type of the scheduler (optional).
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\tparam Value0 ... (optional).
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\tparam ValueN types of source observables (optional).
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\param cn the scheduler to synchronize sources from different contexts (optional).
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\param v0 ... (optional).
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\param vn source observables (optional).
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\return Observable that emits the same sequence as whichever of the source observables first emitted an item or sent a termination notification.
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If scheduler is omitted, identity_current_thread is used.
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\sample
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\snippet amb.cpp threaded implicit amb sample
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\snippet output.txt threaded implicit amb sample
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\snippet amb.cpp implicit amb sample
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\snippet output.txt implicit amb sample
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\snippet amb.cpp amb sample
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\snippet output.txt amb sample
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\snippet amb.cpp threaded amb sample
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\snippet output.txt threaded amb sample
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*/
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#if !defined(RXCPP_OPERATORS_RX_AMB_HPP)
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#define RXCPP_OPERATORS_RX_AMB_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 amb_invalid_arguments {};
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template<class... AN>
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struct amb_invalid : public rxo::operator_base<amb_invalid_arguments<AN...>> {
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using type = observable<amb_invalid_arguments<AN...>, amb_invalid<AN...>>;
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};
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template<class... AN>
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using amb_invalid_t = typename amb_invalid<AN...>::type;
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template<class T, class Observable, class Coordination>
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struct amb
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: public operator_base<rxu::value_type_t<T>>
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{
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//static_assert(is_observable<Observable>::value, "amb requires an observable");
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//static_assert(is_observable<T>::value, "amb requires an observable that contains observables");
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typedef amb<T, Observable, Coordination> this_type;
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typedef rxu::decay_t<T> source_value_type;
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typedef rxu::decay_t<Observable> source_type;
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typedef typename source_type::source_operator_type source_operator_type;
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typedef typename source_value_type::value_type value_type;
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typedef rxu::decay_t<Coordination> 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(source_operator_type o, coordination_type sf)
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: source_operator(std::move(o))
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, coordination(std::move(sf))
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{
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}
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source_operator_type source_operator;
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coordination_type coordination;
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};
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values initial;
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amb(const source_type& o, coordination_type sf)
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: initial(o.source_operator, std::move(sf))
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{
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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 amb_state_type
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: public std::enable_shared_from_this<amb_state_type>
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, public values
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{
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amb_state_type(values i, coordinator_type coor, output_type oarg)
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: values(i)
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, source(i.source_operator)
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, coordinator(std::move(coor))
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, out(std::move(oarg))
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, pendingObservables(0)
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, firstEmitted(false)
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{
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}
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observable<source_value_type, source_operator_type> source;
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coordinator_type coordinator;
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output_type out;
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int pendingObservables;
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bool firstEmitted;
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std::vector<composite_subscription> innerSubscriptions;
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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<amb_state_type>(initial, std::move(coordinator), std::move(scbr));
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composite_subscription outercs;
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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(outercs);
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auto source = on_exception(
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[&](){return state->coordinator.in(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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outercs,
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// on_next
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[state](source_value_type st) {
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if (state->firstEmitted)
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return;
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composite_subscription innercs;
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state->innerSubscriptions.push_back(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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auto innercstoken = state->out.add(innercs);
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innercs.add(make_subscription([state, innercstoken](){
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state->out.remove(innercstoken);
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}));
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auto selectedSource = state->coordinator.in(st);
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auto current_id = state->pendingObservables++;
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// this subscribe does not share the source subscription
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// so that when it is unsubscribed the source will continue
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auto sinkInner = make_subscriber<value_type>(
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state->out,
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innercs,
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// on_next
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[state, st, current_id](value_type ct) {
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state->out.on_next(std::move(ct));
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if (!state->firstEmitted) {
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state->firstEmitted = true;
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auto do_unsubscribe = [](composite_subscription cs) {
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cs.unsubscribe();
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};
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std::for_each(state->innerSubscriptions.begin(), state->innerSubscriptions.begin() + current_id, do_unsubscribe);
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std::for_each(state->innerSubscriptions.begin() + current_id + 1, state->innerSubscriptions.end(), do_unsubscribe);
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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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state->out.on_completed();
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}
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);
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auto selectedSinkInner = state->coordinator.out(sinkInner);
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selectedSource.subscribe(std::move(selectedSinkInner));
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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->pendingObservables == 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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};
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}
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/*! @copydoc rx-amb.hpp
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*/
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template<class... AN>
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auto amb(AN&&... an)
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-> operator_factory<amb_tag, AN...> {
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return operator_factory<amb_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<amb_tag>
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{
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template<class Observable,
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class Enabled = rxu::enable_if_all_true_type_t<
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is_observable<Observable>>,
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class SourceValue = rxu::value_type_t<Observable>,
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class Amb = rxo::detail::amb<SourceValue, rxu::decay_t<Observable>, identity_one_worker>,
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class Value = rxu::value_type_t<SourceValue>,
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class Result = observable<Value, Amb>
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>
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static Result member(Observable&& o) {
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return Result(Amb(std::forward<Observable>(o), identity_current_thread()));
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}
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template<class Observable, class Coordination,
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class Enabled = rxu::enable_if_all_true_type_t<
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is_observable<Observable>,
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is_coordination<Coordination>>,
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class SourceValue = rxu::value_type_t<Observable>,
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class Amb = rxo::detail::amb<SourceValue, rxu::decay_t<Observable>, rxu::decay_t<Coordination>>,
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class Value = rxu::value_type_t<SourceValue>,
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class Result = observable<Value, Amb>
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>
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static Result member(Observable&& o, Coordination&& cn) {
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return Result(Amb(std::forward<Observable>(o), std::forward<Coordination>(cn)));
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}
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template<class Observable, class Value0, class... ValueN,
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class Enabled = rxu::enable_if_all_true_type_t<
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all_observables<Observable, Value0, ValueN...>>,
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class EmittedValue = rxu::value_type_t<Observable>,
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class SourceValue = observable<EmittedValue>,
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class ObservableObservable = observable<SourceValue>,
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class Amb = typename rxu::defer_type<rxo::detail::amb, SourceValue, ObservableObservable, identity_one_worker>::type,
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class Value = rxu::value_type_t<Amb>,
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class Result = observable<Value, Amb>
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>
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static Result member(Observable&& o, Value0&& v0, ValueN&&... vn) {
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return Result(Amb(rxs::from(o.as_dynamic(), v0.as_dynamic(), vn.as_dynamic()...), identity_current_thread()));
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}
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template<class Observable, class Coordination, class Value0, class... ValueN,
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class Enabled = rxu::enable_if_all_true_type_t<
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all_observables<Observable, Value0, ValueN...>,
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is_coordination<Coordination>>,
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class EmittedValue = rxu::value_type_t<Observable>,
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class SourceValue = observable<EmittedValue>,
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class ObservableObservable = observable<SourceValue>,
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class Amb = typename rxu::defer_type<rxo::detail::amb, SourceValue, ObservableObservable, rxu::decay_t<Coordination>>::type,
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class Value = rxu::value_type_t<Amb>,
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class Result = observable<Value, Amb>
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>
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static Result member(Observable&& o, Coordination&& cn, Value0&& v0, ValueN&&... vn) {
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return Result(Amb(rxs::from(o.as_dynamic(), v0.as_dynamic(), vn.as_dynamic()...), std::forward<Coordination>(cn)));
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}
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template<class... AN>
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static operators::detail::amb_invalid_t<AN...> member(AN...) {
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std::terminate();
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return {};
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static_assert(sizeof...(AN) == 10000, "amb takes (optional Coordination, optional Value0, optional ValueN...)");
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}
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};
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}
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#endif
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