rx-finally.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_FINALLY_HPP)
#define RXCPP_OPERATORS_RX_FINALLY_HPP

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

namespace rxcpp {

namespace operators {

namespace detail {

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

template<class... AN>
struct finally_invalid : public rxo::operator_base<finally_invalid_arguments<AN...>> {
    using type = observable<finally_invalid_arguments<AN...>, finally_invalid<AN...>>;
};
template<class... AN>
using finally_invalid_t = typename finally_invalid<AN...>::type;

template<class T, class LastCall>
struct finally
{
    typedef rxu::decay_t<T> source_value_type;
    typedef rxu::decay_t<LastCall> last_call_type;
    last_call_type last_call;

    finally(last_call_type lc)
        : last_call(std::move(lc))
    {
    }

    template<class Subscriber>
    struct finally_observer
    {
        typedef finally_observer<Subscriber> this_type;
        typedef source_value_type value_type;
        typedef rxu::decay_t<Subscriber> dest_type;
        typedef observer<value_type, this_type> observer_type;
        dest_type dest;

        finally_observer(dest_type d)
            : dest(std::move(d))
        {
        }
        void on_next(source_value_type v) const {
            dest.on_next(v);
        }
        void on_error(std::exception_ptr e) const {
            dest.on_error(e);
        }
        void on_completed() const {
            dest.on_completed();
        }

        static subscriber<value_type, observer_type> make(dest_type d, const last_call_type& lc) {
            auto dl = d.get_subscription();
            composite_subscription cs;
            dl.add(cs);
            cs.add([=](){
                dl.unsubscribe();
                lc();
            });
            return make_subscriber<value_type>(cs, this_type(d));
        }
    };

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

}

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

}

template<>
struct member_overload<finally_tag>
{
    template<class Observable, class LastCall,
        class SourceValue = rxu::value_type_t<Observable>,
        class Enabled = rxu::enable_if_all_true_type_t<
            is_observable<Observable>>,
        class Finally = rxo::detail::finally<SourceValue, rxu::decay_t<LastCall>>>
    static auto member(Observable&& o, LastCall&& lc)
        -> decltype(o.template lift<SourceValue>(Finally(std::forward<LastCall>(lc)))) {
        return      o.template lift<SourceValue>(Finally(std::forward<LastCall>(lc)));
    }

    template<class... AN>
    static operators::detail::finally_invalid_t<AN...> member(const AN&...) {
        std::terminate();
        return {};
        static_assert(sizeof...(AN) == 10000, "finally takes (LastCall)");
    }
};

}

#endif