| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.commons.configuration2.event; |
| |
| import java.io.Serializable; |
| import java.util.HashSet; |
| import java.util.Set; |
| |
| /** |
| * <p> |
| * A class representing an event type. |
| * </p> |
| * <p> |
| * The events produced by <em>Commons Configuration</em> all have a specific type. The event type can be used to |
| * determine the meaning of a specific event. It also acts as filter criterion when event listeners are registered. The |
| * listener is then called only for events of this type or derived types. The events in this library form a natural |
| * hierarchy with base types and more specialized types. By specifying an appropriate event type at listener |
| * registration time, it can be determined on a fine-granular basis which events are propagated to the listener. |
| * </p> |
| * <p> |
| * Note: Users familiar with JavaFX probably recognize this approach to event handling. It allows for generic event |
| * listener interfaces and a natural selection of events to be processed. |
| * </p> |
| * |
| * @since 2.0 |
| * @param <T> the event associated with this type |
| */ |
| public class EventType<T extends Event> implements Serializable { |
| /** Serial version UID. */ |
| private static final long serialVersionUID = 20150416L; |
| |
| /** Constant for the format used by toString(). */ |
| private static final String FMT_TO_STRING = "%s [ %s ]"; |
| |
| /** |
| * Returns a set with all event types that are super types of the specified type. This set contains the direct and |
| * indirect super types and also includes the given type itself. The passed in type may be <b>null</b>, then an empty |
| * set is returned. |
| * |
| * @param eventType the event type in question |
| * @return a set with all super event types |
| */ |
| public static Set<EventType<?>> fetchSuperEventTypes(final EventType<?> eventType) { |
| final Set<EventType<?>> types = new HashSet<>(); |
| EventType<?> currentType = eventType; |
| while (currentType != null) { |
| types.add(currentType); |
| currentType = currentType.getSuperType(); |
| } |
| return types; |
| } |
| |
| /** |
| * Checks whether an event type is derived from another type. This implementation tests whether {@code baseType} is a |
| * direct or indirect super type of {@code derivedType}. If one of the types is <b>null</b>, result is <b>false</b>. |
| * |
| * @param derivedType the derived event type |
| * @param baseType the base event type |
| * @return <b>true</b> if the derived type is an instance of the base type, <b>false</b> otherwise |
| */ |
| public static boolean isInstanceOf(final EventType<?> derivedType, final EventType<?> baseType) { |
| EventType<?> currentType = derivedType; |
| while (currentType != null) { |
| if (currentType == baseType) { |
| return true; |
| } |
| currentType = currentType.getSuperType(); |
| } |
| return false; |
| } |
| |
| /** Stores the super type of this type. */ |
| private final EventType<? super T> superType; |
| |
| /** A name for this event type. */ |
| private final String name; |
| |
| /** |
| * Creates a new instance of {@code EventType} and initializes it with the super type and a type name. If no super type |
| * is specified, this is the root event type. |
| * |
| * @param superEventType the super event type |
| * @param typeName the name of this event type |
| */ |
| public EventType(final EventType<? super T> superEventType, final String typeName) { |
| superType = superEventType; |
| name = typeName; |
| } |
| |
| /** |
| * Gets the name of this event type. The name has no specific semantic meaning. It is just used for debugging |
| * purposes and also part of the string representation of this event type. |
| * |
| * @return the event type name |
| */ |
| public String getName() { |
| return name; |
| } |
| |
| /** |
| * Gets the super event type. Result is <b>null</b> for the root event type. |
| * |
| * @return the super event type |
| */ |
| public EventType<? super T> getSuperType() { |
| return superType; |
| } |
| |
| /** |
| * Returns a string representation for this object. This method is mainly overridden for debugging purposes. The |
| * returned string contains the name of this event type. |
| * |
| * @return a string for this object |
| */ |
| @Override |
| public String toString() { |
| return String.format(FMT_TO_STRING, getClass().getSimpleName(), getName()); |
| } |
| } |