feat: API simplification, allow multiple instances

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

@@ -7,6 +7,7 @@ import ftbsc.geb.api.IListener;
 
 import java.util.Map;
 import java.util.ServiceLoader;
+import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
 /**
@@ -17,7 +18,7 @@ public class GEB implements IBus {
 	/**
 	 * A {@link Map} tying each listener class to its instance.
 	 */
-	private final Map<Class<? extends IListener>, IListener> listenerMap;
+	private final Map<Class<? extends IListener>, Set<IListener>> listenerMap;
 
 	/**
 	 * A {@link Map} tying each event class to the appropriate dispatcher.
@@ -31,7 +32,7 @@ public class GEB implements IBus {
 		this.listenerMap = new ConcurrentHashMap<>();
 		this.dispatchMap = new ConcurrentHashMap<>();
 		for(IEventDispatcher dispatcher : ServiceLoader.load(IEventDispatcher.class))
-			dispatchMap.put(dispatcher.eventType(), dispatcher);
+			this.dispatchMap.put(dispatcher.eventType(), dispatcher);
 	}
 
 	/**
@@ -40,7 +41,10 @@ public class GEB implements IBus {
 	 */
 	@Override
 	public void registerListener(IListener listener) {
-		this.listenerMap.put(listener.getClass(), listener);
+		this.listenerMap.putIfAbsent(
+			listener.getClass(),
+			ConcurrentHashMap.newKeySet()
+		);
 	}
 
 	/**
@@ -49,13 +53,19 @@ public class GEB implements IBus {
 	 */
 	@Override
 	public void unregisterListener(IListener listener) {
-		this.listenerMap.remove(listener.getClass());
+		this.listenerMap.computeIfPresent(
+			listener.getClass(),
+			(k, l) -> {
+				l.remove(listener);
+				return l;
+			}
+		);
 	}
 
 	/**
 	 * 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
+	 * @return false if the event was canceled, true otherwise
 	 */
 	@Override
 	public boolean handleEvent(IEvent event) {

src/main/java/ftbsc/geb/api/IBus.java

@@ -14,9 +14,6 @@ public interface IBus {
 
 	/**
 	 * Unregister a listener from the bus.
-	 * While sensible implementations can get this quite fast, it's generally
-	 * faster to use {@link IListener#isActive()}, so only use this if you
-	 * *mean* to unregister for good.
 	 * @param listener the listener
 	 */
 	void unregisterListener(IListener listener);
@@ -24,7 +21,7 @@ public interface IBus {
 	/**
 	 * 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
+	 * @return false if the event was canceled, true otherwise
 	 */
 	boolean handleEvent(IEvent event);
 }

src/main/java/ftbsc/geb/api/IEventDispatcher.java

@@ -1,6 +1,7 @@
 package ftbsc.geb.api;
 
 import java.util.Map;
+import java.util.Set;
 
 /**
  * The interface that the generated dispatchers will all use.
@@ -12,10 +13,10 @@ public interface IEventDispatcher {
 	/**
 	 * Calls all listeners for the given event.
 	 * @param event the event to call
-	 * @param listeners a map mapping each {@link IListener} class to its instance
+	 * @param listeners a map mapping each {@link IListener} class to its instances
 	 * @return the value {@link IBus#handleEvent(IEvent)} will return for this
 	 */
-	boolean callListeners(IEvent event, Map<Class<? extends IListener>, IListener> listeners);
+	boolean callListeners(IEvent event, Map<Class<? extends IListener>, Set<IListener>> listeners);
 
 	/**
 	 * @return the {@link Class} representing the event this dispatcher works with

src/main/java/ftbsc/geb/api/IListener.java

@@ -4,9 +4,4 @@ package ftbsc.geb.api;
  * The common interface for all classes that contain GEB listeners.
  * @since 0.1.0
  */
-public interface IListener {
+public interface IListener {}
-	/**
-	 * @return whether the listeners in this class should be considered to be active
-	 */
-	boolean isActive();
-}