rx-subscribe_on.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_SUBSCRIBE_ON_HPP)
#define RXCPP_OPERATORS_RX_SUBSCRIBE_ON_HPP

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

namespace rxcpp {

namespace operators {

namespace detail {

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

template<class... AN>
struct subscribe_on_invalid : public rxo::operator_base<subscribe_on_invalid_arguments<AN...>> {
    using type = observable<subscribe_on_invalid_arguments<AN...>, subscribe_on_invalid<AN...>>;
};
template<class... AN>
using subscribe_on_invalid_t = typename subscribe_on_invalid<AN...>::type;

template<class T, class Observable, class Coordination>
struct subscribe_on : public operator_base<T>
{
    typedef rxu::decay_t<Observable> source_type;
    typedef rxu::decay_t<Coordination> coordination_type;
    typedef typename coordination_type::coordinator_type coordinator_type;
    struct subscribe_on_values
    {
        ~subscribe_on_values()
        {
        }
        subscribe_on_values(source_type s, coordination_type sf)
            : source(std::move(s))
            , coordination(std::move(sf))
        {
        }
        source_type source;
        coordination_type coordination;
    private:
        subscribe_on_values& operator=(subscribe_on_values o) RXCPP_DELETE;
    };
    const subscribe_on_values initial;

    ~subscribe_on()
    {
    }
    subscribe_on(source_type s, coordination_type sf)
        : initial(std::move(s), std::move(sf))
    {
    }

    template<class Subscriber>
    void on_subscribe(Subscriber s) const {

        typedef Subscriber output_type;
        struct subscribe_on_state_type
            : public std::enable_shared_from_this<subscribe_on_state_type>
            , public subscribe_on_values
        {
            subscribe_on_state_type(const subscribe_on_values& i, const output_type& oarg)
                : subscribe_on_values(i)
                , out(oarg)
            {
            }
            composite_subscription source_lifetime;
            output_type out;
        private:
            subscribe_on_state_type& operator=(subscribe_on_state_type o) RXCPP_DELETE;
        };

        composite_subscription coordinator_lifetime;

        auto coordinator = initial.coordination.create_coordinator(coordinator_lifetime);

        auto controller = coordinator.get_worker();

        // take a copy of the values for each subscription
        auto state = std::make_shared<subscribe_on_state_type>(initial, std::move(s));

        auto sl = state->source_lifetime;
        auto ol = state->out.get_subscription();

        auto disposer = [=](const rxsc::schedulable&){
            sl.unsubscribe();
            ol.unsubscribe();
            coordinator_lifetime.unsubscribe();
        };
        auto selectedDisposer = on_exception(
            [&](){return coordinator.act(disposer);},
            state->out);
        if (selectedDisposer.empty()) {
            return;
        }
        
        state->source_lifetime.add([=](){
            controller.schedule(selectedDisposer.get());
        });

        state->out.add([=](){
            sl.unsubscribe();
            ol.unsubscribe();
            coordinator_lifetime.unsubscribe();
        });

        auto producer = [=](const rxsc::schedulable&){
            state->source.subscribe(state->source_lifetime, state->out);
        };

        auto selectedProducer = on_exception(
            [&](){return coordinator.act(producer);},
            state->out);
        if (selectedProducer.empty()) {
            return;
        }

        controller.schedule(selectedProducer.get());
    }
private:
    subscribe_on& operator=(subscribe_on o) RXCPP_DELETE;
};

}

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

}

template<>
struct member_overload<subscribe_on_tag>
{
    template<class Observable, class Coordination,
        class Enabled = rxu::enable_if_all_true_type_t<
            is_observable<Observable>,
            is_coordination<Coordination>>,
        class SourceValue = rxu::value_type_t<Observable>,
        class SubscribeOn = rxo::detail::subscribe_on<SourceValue, rxu::decay_t<Observable>, rxu::decay_t<Coordination>>,
        class Value = rxu::value_type_t<SubscribeOn>,
        class Result = observable<Value, SubscribeOn>>
    static Result member(Observable&& o, Coordination&& cn) {
        return Result(SubscribeOn(std::forward<Observable>(o), std::forward<Coordination>(cn)));
    }

    template<class... AN>
    static operators::detail::subscribe_on_invalid_t<AN...> member(AN...) {
        std::terminate();
        return {};
        static_assert(sizeof...(AN) == 10000, "subscribe_on takes (Coordination)");
    }
};

}

#endif