rx-map.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_MAP_HPP)
#define RXCPP_OPERATORS_RX_MAP_HPP

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

namespace rxcpp {

namespace operators {

namespace detail {

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

template<class... AN>
struct map_invalid : public rxo::operator_base<map_invalid_arguments<AN...>> {
    using type = observable<map_invalid_arguments<AN...>, map_invalid<AN...>>;
};
template<class... AN>
using map_invalid_t = typename map_invalid<AN...>::type;

template<class T, class Selector>
struct map
{
    typedef rxu::decay_t<T> source_value_type;
    typedef rxu::decay_t<Selector> select_type;
    typedef decltype((*(select_type*)nullptr)(*(source_value_type*)nullptr)) value_type;
    select_type selector;

    map(select_type s)
        : selector(std::move(s))
    {
    }

    template<class Subscriber>
    struct map_observer
    {
        typedef map_observer<Subscriber> this_type;
        typedef decltype((*(select_type*)nullptr)(*(source_value_type*)nullptr)) value_type;
        typedef rxu::decay_t<Subscriber> dest_type;
        typedef observer<source_value_type, this_type> observer_type;
        dest_type dest;
        mutable select_type selector;

        map_observer(dest_type d, select_type s)
            : dest(std::move(d))
            , selector(std::move(s))
        {
        }
        template<class Value>
        void on_next(Value&& v) const {
            auto selected = on_exception(
                [&](){
                    return this->selector(std::forward<Value>(v));},
                dest);
            if (selected.empty()) {
                return;
            }
            dest.on_next(std::move(selected.get()));
        }
        void on_error(std::exception_ptr e) const {
            dest.on_error(e);
        }
        void on_completed() const {
            dest.on_completed();
        }

        static subscriber<source_value_type, observer_type> make(dest_type d, select_type s) {
            auto cs = d.get_subscription();
            return make_subscriber<source_value_type>(std::move(cs), observer_type(this_type(std::move(d), std::move(s))));
        }
    };

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

}

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

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

}

template<>
struct member_overload<map_tag>
{
    template<class Observable, class Selector,
        class Enabled = rxu::enable_if_all_true_type_t<
            is_observable<Observable>>,
        class ResolvedSelector = rxu::decay_t<Selector>,
        class SourceValue = rxu::value_type_t<Observable>,
        class Map = rxo::detail::map<SourceValue, ResolvedSelector>,
        class Value = rxu::value_type_t<Map>>
    static auto member(Observable&& o, Selector&& s)
        -> decltype(o.template lift<Value>(Map(std::forward<Selector>(s)))) {
        return      o.template lift<Value>(Map(std::forward<Selector>(s)));
    }

    template<class... AN>
    static operators::detail::map_invalid_t<AN...> member(const AN...) {
        std::terminate();
        return {};
        static_assert(sizeof...(AN) == 10000, "map takes Selector");
    }
};

}

#endif