From 6fd7cec7d4bbf5aeb361b3f1337671bb0f9af61b Mon Sep 17 00:00:00 2001 From: Loek Le Blansch Date: Thu, 28 Nov 2024 10:13:11 +0100 Subject: manager mediator refactor --- src/crepe/manager/EventManager.h | 161 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 161 insertions(+) create mode 100644 src/crepe/manager/EventManager.h (limited to 'src/crepe/manager/EventManager.h') diff --git a/src/crepe/manager/EventManager.h b/src/crepe/manager/EventManager.h new file mode 100644 index 0000000..d634f54 --- /dev/null +++ b/src/crepe/manager/EventManager.h @@ -0,0 +1,161 @@ +#pragma once + +#include +#include +#include +#include + +#include "../api/Event.h" +#include "../api/EventHandler.h" + +namespace crepe { + +//! Event listener unique ID +typedef size_t subscription_t; + +/** + * \brief Event channel + * + * Events can be sent to a specific channel, which prevents listeners on other channels from + * being called. The default channel is EventManager::CHANNEL_ALL, which calls all listeners. + */ +typedef size_t event_channel_t; + +/** + * \class EventManager + * \brief Manages event subscriptions, triggers, and queues, enabling decoupled event handling. + * + * The `EventManager` acts as a centralized event system. It allows for registering callbacks + * for specific event types, triggering events synchronously, queueing events for later + * processing, and managing subscriptions via unique identifiers. + */ +class EventManager { +public: + static constexpr const event_channel_t CHANNEL_ALL = -1; + + /** + * \brief Get the singleton instance of the EventManager. + * + * This method returns the unique instance of the EventManager, creating it if it + * doesn't already exist. Ensures only one instance is active in the program. + * + * \return Reference to the singleton instance of the EventManager. + */ + static EventManager & get_instance(); + + /** + * \brief Subscribe to a specific event type. + * + * Registers a callback for a given event type and optional channel. Each callback + * is assigned a unique subscription ID that can be used for later unsubscription. + * + * \tparam EventType The type of the event to subscribe to. + * \param callback The callback function to be invoked when the event is triggered. + * \param channel The channel number to subscribe to (default is CHANNEL_ALL, which listens to all channels). + * \return A unique subscription ID associated with the registered callback. + */ + template + subscription_t subscribe(const EventHandler & callback, + event_channel_t channel = CHANNEL_ALL); + + /** + * \brief Unsubscribe a previously registered callback. + * + * Removes a callback from the subscription list based on its unique subscription ID. + * + * \param event_id The unique subscription ID of the callback to remove. + */ + void unsubscribe(subscription_t event_id); + + /** + * \brief Trigger an event immediately. + * + * Synchronously invokes all registered callbacks for the given event type on the specified channel. + * + * \tparam EventType The type of the event to trigger. + * \param event The event instance to pass to the callbacks. + * \param channel The channel to trigger the event on (default is CHANNEL_ALL, which triggers on all channels). + */ + template + void trigger_event(const EventType & event = {}, event_channel_t channel = CHANNEL_ALL); + + /** + * \brief Queue an event for later processing. + * + * Adds an event to the event queue to be processed during the next call to `dispatch_events`. + * + * \tparam EventType The type of the event to queue. + * \param event The event instance to queue. + * \param channel The channel to associate with the event (default is CHANNEL_ALL). + */ + template + void queue_event(const EventType & event = {}, event_channel_t channel = CHANNEL_ALL); + + /** + * \brief Process all queued events. + * + * Iterates through the event queue and triggers callbacks for each queued event. + * Events are removed from the queue once processed. + */ + void dispatch_events(); + + /** + * \brief Clear all subscriptions. + * + * Removes all registered event handlers and clears the subscription list. + */ + void clear(); + +private: + /** + * \brief Default constructor for the EventManager. + * + * Constructor is private to enforce the singleton pattern. + */ + EventManager() = default; + + /** + * \struct QueueEntry + * \brief Represents an entry in the event queue. + */ + struct QueueEntry { + std::unique_ptr event; ///< The event instance. + event_channel_t channel = CHANNEL_ALL; ///< The channel associated with the event. + std::type_index type; ///< The type of the event. + }; + + /** + * \brief Internal event handler + * + * This function processes a single event, and is used to process events both during + * EventManager::dispatch_events and inside EventManager::trigger_event + * + * \param type \c typeid of concrete Event class + * \param channel Event channel + * \param data Event data + */ + void handle_event(std::type_index type, event_channel_t channel, const Event & data); + + /** + * \struct CallbackEntry + * \brief Represents a registered event handler callback. + */ + struct CallbackEntry { + std::unique_ptr callback; ///< The callback function wrapper. + event_channel_t channel = CHANNEL_ALL; ///< The channel this callback listens to. + subscription_t id = -1; ///< Unique subscription ID. + }; + + //! The queue of events to be processed during dispatch. + std::vector events_queue; + + //! A map of event type to registered callbacks. + std::unordered_map> subscribers; + + //! Counter to generate unique subscription IDs. + subscription_t subscription_counter = 0; +}; + +} // namespace crepe + +#include "EventManager.hpp" -- cgit v1.2.3