event_dispatcher.h

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/*!****************************************************************//*!*
 * \file   event_dispatcher.h
 * \brief  Event dispatcher class implementation module.
 * 
 * \author Sabitov Kirill
 * \date   25 June 2022
 *********************************************************************/
 
#pragma once
 
#include "event.h"
#include "utilities/string/string_id.h"
 
namespace scl
{
    class event_dispatcher
    {
        template <typename Tevent>
        using event_callback = std::function<bool(Tevent &)>;
        using base_event_callback = std::function<bool(event &)>;
        using callback_list = std::vector<base_event_callback>;
 
    private: 
        static std::map<string_id, callback_list> EventHandlers;
 
    public: 
        /*!*
         * Add event listner to specific event function.
         *
         * \tparam Tevent - event to set listner to.
         * \param Event - callback to be called on event dispatch.
         * \return None.
         */
        template <typename Tevent>
        static void AddEventListner(base_event_callback &&EventCallback)
        {
            auto event_handlers = EventHandlers.find(Tevent::StaticType);
            if (event_handlers == EventHandlers.end())
                EventHandlers.emplace(Tevent::StaticType, std::vector { std::move(EventCallback) });
            else
                event_handlers->second.push_back(std::move(EventCallback));
        }
 
        /*!*
         * Add event listner to specific event function.
         *
         * \tparam Tevent - event to set listner to.
         * \param Event - callback to be called on event dispatch.
         * \return None.
         */
        template <typename Tevent>
        static void AddEventListner(std::function<bool(Tevent &)> &&EventCallback)
        {
            AddEventListner<Tevent>([callback = std::move(EventCallback)](event &Event)
            {
                if (Event.GetType() != Tevent::StaticType) return false;
                return callback(static_cast<Tevent &>(Event));
            });
        }
 
        /*!*
         * Dispatch specific event function.
         * Calls all callbacks, listing to that event.
         * 
         * \param Event - event to handle.
         * \return None.
         */
        template <typename Tevent>
        static void Invoke(Tevent &Event)
        {
            std::map<string_id, callback_list>::iterator event_handlers = EventHandlers.find(Event.GetType());
            if (event_handlers == EventHandlers.end()) return;
 
            for (const auto &callback : event_handlers->second)
            {
                Event.Handled |= callback(Event);
                if (Event.Handled) break;
            }
        }
    };
}