coroActivity.hpp

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#ifndef RAD_COROACTIVITY_HPP
#define RAD_COROACTIVITY_HPP
 
#define BOOST_COROUTINES_NO_DEPRECATION_WARNING
 
#include <tuple>
 
#include <scxml4cpp/Activity.h>
#include <boost/asio/io_context.hpp>
#include <boost/asio/spawn.hpp>
 
namespace rad {
 
namespace detail {
 
template <class T, class... Args, std::size_t... Is>
std::shared_ptr<T> MakeSharedFromTupleImpl(std::tuple<Args...>& t, std::index_sequence<Is...>) {
    return std::make_shared<T>(std::get<Is>(t)...);
}
 
}  // namespace detail
 
template <class T, class... Args>
std::shared_ptr<T> MakeSharedFromTuple(std::tuple<Args...>& args) {
    return detail::MakeSharedFromTupleImpl<T>(args, std::index_sequence_for<Args...>{});
}

template <class CORO, class... Args>
class CoroActivity : public scxml4cpp::Activity {
   public:
    explicit CoroActivity(std::string const& id, boost::asio::io_context& io_ctx, Args... args)
        : scxml4cpp::Activity(id), m_io_ctx(io_ctx), m_args(args...) {}

    void start(scxml4cpp::Context* c) override {
        stop(c);
        m_coro = MakeSharedFromTuple<CORO, Args...>(m_args);
        // Launch coroutine
#if BOOST_VERSION >= 108000
        boost::asio::spawn(m_io_ctx,
                           [&](boost::asio::yield_context yield) { m_coro->operator()(yield); },
                           [](std::exception_ptr e) { if (e) std::rethrow_exception(e); });
#else // TODO remove when dropping support for old boost versions
        boost::asio::spawn(m_io_ctx,
                           [&](boost::asio::yield_context yield) { m_coro->operator()(yield); });
#endif // BOOST_VERSION
    }

    void stop(scxml4cpp::Context* c) override {
        if (m_coro) {
            // Cancel coroutine and detach it
            m_coro->Cancel();
            m_coro.reset();
        }
    }
 
   private:
    boost::asio::io_context& m_io_ctx;
    std::tuple<Args...> m_args;
    std::shared_ptr<CORO> m_coro;
};
 
}  // namespace rad
#endif  // #ifndef RAD_COROACTIVITY_HPP