add readOnly support

core/src/main/java/io/github/mmm/event/AbstractEventSender.java

@@ -1,73 +1,86 @@
-/* Copyright (c) The m-m-m Team, Licensed under the Apache License, Version 2.0
- * http://www.apache.org/licenses/LICENSE-2.0 */
-package io.github.mmm.event;
-
-/**
- * Implementation of {@link EventSource}.
- *
- * @param <E> the type of the events to {@link EventListener#onEvent(Object) send}.
- * @param <L> the type of the {@link EventListener listeners}.
- * @since 1.0.0
- */
-public abstract class AbstractEventSender<E, L extends EventListener<?/* super E */> >
-    extends AbstractEventSource<E, L> {
-
-  private EventSourceAdapter<E, L> eventAdapter;
-
-  /**
-   * The constructor.
-   */
-  public AbstractEventSender() {
-
-    super();
-    this.eventAdapter = EventSourceAdapter.empty();
-  }
-
-  @Override
-  protected void doAddListener(EventListener<E> listener) {
-
-    this.eventAdapter = this.eventAdapter.addListener(listener);
-  }
-
-  @SuppressWarnings({ "rawtypes", "unchecked" })
-  @Override
-  public boolean removeListener(L listener) {
-
-    EventSourceAdapter<E, L> adapter = this.eventAdapter.removeListener((EventListener) listener);
-    if (adapter == null) {
-      return false;
-    }
-    this.eventAdapter = adapter;
-    return true;
-  }
-
-  /**
-   * @return {@code true} if at least one {@link EventListener} is {@link #addListener(EventListener) registered},
-   *         {@code false} otherwise.
-   */
-  protected boolean hasListeners() {
-
-    return this.eventAdapter.hasListeners();
-  }
-
-  /**
-   * @return the {@link EventSourceAdapter}.
-   */
-  protected EventSourceAdapter<E, L> getEventAdapter() {
-
-    return this.eventAdapter;
-  }
-
-  /**
-   * @param event the event to {@link EventListener#onEvent(Object) send} to all {@link #addListener(EventListener)
-   *        registered} {@link EventListener}s.
-   * @return {@code true} if the event has actually been dispatched, {@code false} otherwise (no listener was
-   *         {@link #addListener(EventListener) registered} for the event).
-   */
-  @Override
-  protected boolean fireEvent(E event) {
-
-    return this.eventAdapter.fireEvent(event);
-  }
-
-}
+/* Copyright (c) The m-m-m Team, Licensed under the Apache License, Version 2.0
+ * http://www.apache.org/licenses/LICENSE-2.0 */
+package io.github.mmm.event;
+
+/**
+ * Implementation of {@link EventSource}.
+ *
+ * @param <E> the type of the events to {@link EventListener#onEvent(Object) send}.
+ * @param <L> the type of the {@link EventListener listeners}.
+ * @since 1.0.0
+ */
+public abstract class AbstractEventSender<E, L extends EventListener<?/* super E */> >
+    extends AbstractEventSource<E, L> {
+
+  private EventSourceAdapter<E, L> eventAdapter;
+
+  /**
+   * The constructor.
+   */
+  public AbstractEventSender() {
+
+    super();
+    this.eventAdapter = EventSourceAdapter.empty();
+  }
+
+  @Override
+  protected void doAddListener(EventListener<E> listener) {
+
+    this.eventAdapter = this.eventAdapter.addListener(listener);
+  }
+
+  @SuppressWarnings({ "rawtypes", "unchecked" })
+  @Override
+  public boolean removeListener(L listener) {
+
+    EventSourceAdapter<E, L> adapter = this.eventAdapter.removeListener((EventListener) listener);
+    if (adapter == null) {
+      return false;
+    }
+    this.eventAdapter = adapter;
+    return true;
+  }
+
+  /**
+   * @return {@code true} if at least one {@link EventListener} is {@link #addListener(EventListener) registered},
+   *         {@code false} otherwise.
+   */
+  protected boolean hasListeners() {
+
+    return this.eventAdapter.hasListeners();
+  }
+
+  /**
+   * @return the {@link EventSourceAdapter}.
+   */
+  protected EventSourceAdapter<E, L> getEventAdapter() {
+
+    return this.eventAdapter;
+  }
+
+  /**
+   * @param event the event to {@link EventListener#onEvent(Object) send} to all {@link #addListener(EventListener)
+   *        registered} {@link EventListener}s.
+   * @return {@code true} if the event has actually been dispatched, {@code false} otherwise (no listener was
+   *         {@link #addListener(EventListener) registered} for the event).
+   */
+  @Override
+  protected boolean fireEvent(E event) {
+
+    return this.eventAdapter.fireEvent(event);
+  }
+
+  /**
+   * Makes this event sender read-only so it discards all {@link #addListener(EventListener) added}
+   * {@link EventListener}s and prevents future {@link #addListener(EventListener) adding}.<br>
+   * <b>ATTENTION</b>: This is an internal method that shall only be used by code of this library and not by third-party
+   * users.
+   *
+   * @see EventSourceAdapter#readOnly()
+   */
+  protected void makeReadOnly() {
+
+    this.eventAdapter = EventSourceAdapter.readOnly();
+  }
+
+}