src/main/java/ftbsc/geb/GEB.java


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package ftbsc.geb;

import ftbsc.geb.api.IBus;
import ftbsc.geb.api.IEvent;
import ftbsc.geb.api.IEventDispatcher;
import ftbsc.geb.api.IListener;

import java.util.Map;
import java.util.ServiceLoader;
import java.util.concurrent.ConcurrentHashMap;

/**
 * The official GEB implementation of {@link IBus}.
 * @since 0.1.0
 */
public class GEB implements IBus {

   /**
    * The identifier of this bus. Methods
    */
   private final String identifier;

   /**
    * A {@link Map} tying each listener class to its instance.
    */
   private final Map<Class<? extends IListener>, IListener> listenerMap;

   /**
    * A {@link Map} tying each event class to the appropriate dispatcher.
    */
   private final Map<Class<? extends IEvent>, IEventDispatcher> dispatchMap;

   /**
    * The public constructor.
    * @param identifier a {@link String} uniquely identifying this bus
    */
   public GEB(String identifier) {
      this.identifier = identifier;
      this.listenerMap = new ConcurrentHashMap<>();
      this.dispatchMap = new ConcurrentHashMap<>();
      for(IEventDispatcher dispatcher : ServiceLoader.load(IEventDispatcher.class))
         dispatchMap.put(dispatcher.eventType(), dispatcher);
   }

   /**
    * Registers a new listener on the bus.
    * @param listener the listener
    */
   @Override
   public void registerListener(IListener listener) {
      this.listenerMap.put(listener.getClass(), listener);
   }

   /**
    * Dispatches an event, calling all of its listeners that are subscribed to this bus.
    * @param event the event to fire
    * @return true if the event was canceled, false otherwise
    */
   @Override
   public boolean handleEvent(IEvent event) {
      return this.dispatchMap.get(event.getClass()).callListeners(this.identifier, event, this.listenerMap);
   }
}