rx-ignore_elements.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_IGNORE_ELEMENTS_HPP)
#define RXCPP_OPERATORS_RX_IGNORE_ELEMENTS_HPP

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

namespace rxcpp {

namespace operators {

namespace detail {

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

template<class... AN>
struct ignore_elements_invalid : public rxo::operator_base<ignore_elements_invalid_arguments<AN...>> {
    using type = observable<ignore_elements_invalid_arguments<AN...>, ignore_elements_invalid<AN...>>;
};
template<class... AN>
using ignore_elements_invalid_t = typename ignore_elements_invalid<AN...>::type;

template<class T>
struct ignore_elements {
    typedef rxu::decay_t<T> source_value_type;

    template<class Subscriber>
    struct ignore_elements_observer
    {
        typedef ignore_elements_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;

        ignore_elements_observer(dest_type d)
            : dest(d)
        {
        }

        void on_next(source_value_type) const {
            // no-op; ignore element
        }

        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) {
            return make_subscriber<value_type>(d, this_type(d));
        }
    };

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

}

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

}

template<>
struct member_overload<ignore_elements_tag>
{
    template<class Observable,
            class SourceValue = rxu::value_type_t<Observable>,
            class Enabled = rxu::enable_if_all_true_type_t<
                is_observable<Observable>>,
            class IgnoreElements = rxo::detail::ignore_elements<SourceValue>>
    static auto member(Observable&& o)
    -> decltype(o.template lift<SourceValue>(IgnoreElements())) {
        return  o.template lift<SourceValue>(IgnoreElements());
    }

    template<class... AN>
    static operators::detail::ignore_elements_invalid_t<AN...> member(AN...) {
        std::terminate();
        return {};
        static_assert(sizeof...(AN) == 10000, "ignore_elements takes no arguments");
    }
};

}

#endif