from_signal.hpp

//                  ReactivePlusPlus library
//
//          Copyright Aleksey Loginov 2022 - present.
// Distributed under the Boost Software License, Version 1.0.
//    (See accompanying file LICENSE_1_0.txt or copy at
//          https://www.boost.org/LICENSE_1_0.txt)
//
// Project home: https://github.com/AlexInLog/ReactivePlusPlus
//
 
#pragma once
 
#include <rpp/subjects/publish_subject.hpp>
 
#include <rppqt/sources/fwd.hpp>
 
#include <QObject>
#include <tuple>
 
namespace rppqt::details
{
    template<typename... Args>
    struct from_signal_on_event
    {
        using subject = rpp::subjects::publish_subject<std::tuple<std::decay_t<Args>...>>;
 
        decltype(std::declval<subject>().get_observer()) observer;
 
        template<typename... Vals>
        void operator()(Vals&&... vals) const
        {
            observer.on_next(std::make_tuple(std::forward<Vals>(vals)...));
        }
    };
 
    template<typename Arg>
    struct from_signal_on_event<Arg>
    {
        using subject = rpp::subjects::publish_subject<std::decay_t<Arg>>;
        decltype(std::declval<subject>().get_observer()) observer;
 
        template<rpp::constraint::decayed_same_as<Arg> Val>
        void operator()(Val&& val) const
        {
            observer.on_next(std::forward<Val>(val));
        }
    };
 
    template<>
    struct from_signal_on_event<>
    {
        using subject = rpp::subjects::publish_subject<rpp::utils::none>;
        decltype(std::declval<subject>().get_observer()) observer;
 
        void operator()() const
        {
            observer.on_next(rpp::utils::none{});
        }
    };
} // namespace rppqt::details
 
namespace rppqt::source
{
    template<std::derived_from<QObject> TSignalQObject, std::derived_from<TSignalQObject> TObject, typename R, typename... Args>
    auto from_signal(const TObject& object, R (TSignalQObject::*signal)(Args...))
    {
        using on_next_impl = details::from_signal_on_event<Args...>;
        const auto subj    = typename on_next_impl::subject{};
 
        QObject::connect(&object, signal, on_next_impl{subj.get_observer()});
        QObject::connect(&object, &QObject::destroyed, [observer = subj.get_observer()] { observer.on_completed(); });
 
        return subj.get_observable();
    }
} // namespace rppqt::source