#pragma once

#include "detail/typelist.h"

namespace mpm {
namespace detail {
/// root class for polymorphic event hierarchies
class event {
protected:
    //don't dispatch as this type - it's an internal
    //implementation detail
    using dispatch_as = null_t;

    virtual ~event() {}
};

/// forward decl from eventbus.h
template<typename E>
struct dispatch_typelist;
}// namespace detail

//! Publicly inherit from this class to obtain polymorphic
//! event delivery.
template<typename T, typename Base = detail::event>
class enable_polymorphic_dispatch : public Base {
protected:
    // \internal
    // Couldn't use a typelist based on std::tuple here because
    // std::tuple_cat won't work with an incomplete type, and the
    // derived event types are incomplete when decltype(tuple_cat)
    // would be used

#ifdef DOCS
    using dispatch_as = implementation - defined;
#else
    template<typename E>
    friend class detail::dispatch_typelist;
    using dispatch_as = detail::typelist<T, typename Base::dispatch_as>;
#endif
};
}// namespace mpm