add service locator

src/com/blarg/gdx/Services.java

@@ -0,0 +1,62 @@
+package com.blarg.gdx;
+
+import com.badlogic.gdx.Gdx;
+import com.badlogic.gdx.utils.ObjectMap;
+
+/**
+ * Just a simple service locator. Completely up to the user to use this 'correctly.'
+ *
+ * echo $BAD_PRACTICE_COMPLAINTS > /dev/null
+ */
+public class Services {
+	public interface Service {
+		void onRegister();
+		void onUnregister();
+	}
+
+	static final ObjectMap<Class<?>, Object> services = new ObjectMap<Class<?>, Object>();
+
+	public static void register(Object service) {
+		if (service == null)
+			throw new IllegalArgumentException("service can not be null.");
+
+		Class<?> type = service.getClass();
+		if (services.containsKey(type))
+			throw new UnsupportedOperationException("Another service of this type has already been registered.");
+
+		if (type.isAssignableFrom(Service.class))
+			((Service)service).onRegister();
+
+		services.put(type, service);
+		Gdx.app.log("Services", String.format("Registered object of type %s.", type.getSimpleName()));
+	}
+
+	public static void unregister(Class<?> type) {
+		if (type == null)
+			throw new IllegalArgumentException("type can not be null.");
+
+		Object service = services.get(type);
+		if (service == null)
+			return;
+
+		services.remove(type);
+		Gdx.app.log("Services", String.format("Unregistered object of type %s.", type.getSimpleName()));
+
+		if (type.isAssignableFrom(Service.class))
+			((Service)service).onUnregister();
+	}
+
+	public static <T> T get(Class<T> type) {
+		return type.cast(services.get(type));
+	}
+
+	public static void unregisterAll() {
+		Gdx.app.log("Services", "Unregistering all services.");
+		for (ObjectMap.Entry<Class<?>, Object> i : services.entries()) {
+			if (i.key.isAssignableFrom(Service.class))
+				((Service)i.value).onUnregister();
+		}
+
+		services.clear();
+	}
+}