rx-sample_time.hpp

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// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.

#pragma once

#if !defined(RXCPP_OPERATORS_RX_SAMPLE_WITH_TIME_HPP)
#define RXCPP_OPERATORS_RX_SAMPLE_WITH_TIME_HPP

#include "../rx-includes.hpp"

namespace rxcpp {

namespace operators {

namespace detail {

template<class... AN>
struct sample_with_time_invalid_arguments {};

template<class... AN>
struct sample_with_time_invalid : public rxo::operator_base<sample_with_time_invalid_arguments<AN...>> {
    using type = observable<sample_with_time_invalid_arguments<AN...>, sample_with_time_invalid<AN...>>;
};
template<class... AN>
using sample_with_time_invalid_t = typename sample_with_time_invalid<AN...>::type;

template<class T, class Duration, class Coordination>
struct sample_with_time
{
    typedef rxu::decay_t<T> source_value_type;
    typedef rxu::decay_t<Coordination> coordination_type;
    typedef typename coordination_type::coordinator_type coordinator_type;
    typedef rxu::decay_t<Duration> duration_type;

    struct sample_with_time_value
    {
        sample_with_time_value(duration_type p, coordination_type c)
            : period(p)
            , coordination(c)
        {
        }
        duration_type period;
        coordination_type coordination;
    };
    sample_with_time_value initial;

    sample_with_time(duration_type period, coordination_type coordination)
        : initial(period, coordination)
    {
    }

    template<class Subscriber>
    struct sample_with_time_observer
    {
        typedef sample_with_time_observer<Subscriber> this_type;
        typedef T value_type;
        typedef rxu::decay_t<Subscriber> dest_type;
        typedef observer<value_type, this_type> observer_type;

        struct sample_with_time_subscriber_value : public sample_with_time_value
        {
            sample_with_time_subscriber_value(composite_subscription cs, dest_type d, sample_with_time_value v, coordinator_type c)
                : sample_with_time_value(v)
                , cs(std::move(cs))
                , dest(std::move(d))
                , coordinator(std::move(c))
                , worker(coordinator.get_worker())
            {
            }
            composite_subscription cs;
            dest_type dest;
            coordinator_type coordinator;
            rxsc::worker worker;
            mutable rxu::maybe<value_type> value;
        };
        std::shared_ptr<sample_with_time_subscriber_value> state;

        sample_with_time_observer(composite_subscription cs, dest_type d, sample_with_time_value v, coordinator_type c)
            : state(std::make_shared<sample_with_time_subscriber_value>(sample_with_time_subscriber_value(std::move(cs), std::move(d), v, std::move(c))))
        {
            auto localState = state;

            auto disposer = [=](const rxsc::schedulable&){
                localState->cs.unsubscribe();
                localState->dest.unsubscribe();
                localState->worker.unsubscribe();
            };
            auto selectedDisposer = on_exception(
                [&](){ return localState->coordinator.act(disposer); },
                localState->dest);
            if (selectedDisposer.empty()) {
                return;
            }

            localState->dest.add([=](){
                localState->worker.schedule(selectedDisposer.get());
            });
            localState->cs.add([=](){
                localState->worker.schedule(selectedDisposer.get());
            });

            auto produce_sample = [localState](const rxsc::schedulable&) {
                if(!localState->value.empty()) {
                    localState->dest.on_next(*localState->value);
                    localState->value.reset();
                }
            };
            auto selectedProduce = on_exception(
                [&](){ return localState->coordinator.act(produce_sample); },
                localState->dest);
            if (selectedProduce.empty()) {
                return;
            }

            state->worker.schedule_periodically(
                localState->worker.now(),
                localState->period,
                [localState, selectedProduce](const rxsc::schedulable&) {
                    localState->worker.schedule(selectedProduce.get());
                });
        }
        
        void on_next(T v) const {
            auto localState = state;
            auto work = [v, localState](const rxsc::schedulable&) {
                localState->value.reset(v);
            };
            auto selectedWork = on_exception(
                [&](){ return localState->coordinator.act(work); },
                localState->dest);
            if (selectedWork.empty()) {
                return;
            }
            localState->worker.schedule(selectedWork.get());
        }

        void on_error(std::exception_ptr e) const {
            auto localState = state;
            auto work = [e, localState](const rxsc::schedulable&) {
                localState->dest.on_error(e);
            };
            auto selectedWork = on_exception(
                [&](){ return localState->coordinator.act(work); },
                localState->dest);
            if (selectedWork.empty()) {
                return;
            }
            localState->worker.schedule(selectedWork.get());
        }

        void on_completed() const {
            auto localState = state;
            auto work = [localState](const rxsc::schedulable&) {
                localState->dest.on_completed();
            };
            auto selectedWork = on_exception(
                [&](){ return localState->coordinator.act(work); },
                localState->dest);
            if (selectedWork.empty()) {
                return;
            }
            localState->worker.schedule(selectedWork.get());
        }

        static subscriber<T, observer<T, this_type>> make(dest_type d, sample_with_time_value v) {
            auto cs = composite_subscription();
            auto coordinator = v.coordination.create_coordinator();

            return make_subscriber<T>(cs, this_type(cs, std::move(d), std::move(v), std::move(coordinator)));
        }
    };

    template<class Subscriber>
    auto operator()(Subscriber dest) const
        -> decltype(sample_with_time_observer<Subscriber>::make(std::move(dest), initial)) {
        return      sample_with_time_observer<Subscriber>::make(std::move(dest), initial);
    }
};

}

template<class... AN>
auto sample_with_time(AN&&... an)
    ->      operator_factory<sample_with_time_tag, AN...> {
     return operator_factory<sample_with_time_tag, AN...>(std::make_tuple(std::forward<AN>(an)...));
}

}

template<>
struct member_overload<sample_with_time_tag>
{
    template<class Observable, class Duration,
        class Enabled = rxu::enable_if_all_true_type_t<
            is_observable<Observable>,
            rxu::is_duration<Duration>>,
        class SourceValue = rxu::value_type_t<Observable>,
        class SampleWithTime = rxo::detail::sample_with_time<SourceValue, rxu::decay_t<Duration>, identity_one_worker>>
    static auto member(Observable&& o, Duration&& d)
        -> decltype(o.template lift<SourceValue>(SampleWithTime(std::forward<Duration>(d), identity_current_thread()))) {
        return      o.template lift<SourceValue>(SampleWithTime(std::forward<Duration>(d), identity_current_thread()));
    }

    template<class Observable, class Coordination, class Duration,
        class Enabled = rxu::enable_if_all_true_type_t<
            is_observable<Observable>,
            is_coordination<Coordination>,
            rxu::is_duration<Duration>>,
        class SourceValue = rxu::value_type_t<Observable>,
        class SampleWithTime = rxo::detail::sample_with_time<SourceValue, rxu::decay_t<Duration>, rxu::decay_t<Coordination>>>
    static auto member(Observable&& o, Coordination&& cn, Duration&& d)
        -> decltype(o.template lift<SourceValue>(SampleWithTime(std::forward<Duration>(d), std::forward<Coordination>(cn)))) {
        return      o.template lift<SourceValue>(SampleWithTime(std::forward<Duration>(d), std::forward<Coordination>(cn)));
    }

    template<class Observable, class Coordination, class Duration,
        class Enabled = rxu::enable_if_all_true_type_t<
            is_observable<Observable>,
            is_coordination<Coordination>,
            rxu::is_duration<Duration>>,
        class SourceValue = rxu::value_type_t<Observable>,
        class SampleWithTime = rxo::detail::sample_with_time<SourceValue, rxu::decay_t<Duration>, rxu::decay_t<Coordination>>>
    static auto member(Observable&& o, Duration&& d, Coordination&& cn)
        -> decltype(o.template lift<SourceValue>(SampleWithTime(std::forward<Duration>(d), std::forward<Coordination>(cn)))) {
        return      o.template lift<SourceValue>(SampleWithTime(std::forward<Duration>(d), std::forward<Coordination>(cn)));
    }

    template<class... AN>
    static operators::detail::sample_with_time_invalid_t<AN...> member(const AN&...) {
        std::terminate();
        return {};
        static_assert(sizeof...(AN) == 10000, "sample_with_time takes (optional Coordination, required Duration) or (required Duration, optional Coordination)");
    }
};

}

#endif