    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *     http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.configuration2.builder;
    018
    019import org.apache.commons.configuration2.event.Event;
    020import org.apache.commons.configuration2.event.EventType;
    021
    022/**
    023 * <p>
    024 * A base event class for events generated by a {@link ConfigurationBuilder}.
    025 * </p>
    026 * <p>
    027 * Configuration builders can trigger a number of different events. All these events are derived from this class. This
    028 * event base class does not define any additional properties. However, it defines that the event source must be a
    029 * {@code ConfigurationBuilder}.
    030 * </p>
    031 *
    032 * @since 2.0
    033 */
    034public class ConfigurationBuilderEvent extends Event {
    035
    036    private static final long serialVersionUID = -7488811456039315104L;
    037
    038    /** The common super type for all events related to configuration builders. */
    039    public static final EventType<ConfigurationBuilderEvent> ANY = new EventType<>(Event.ANY, "BUILDER");
    040
    041    /**
    042     * The specific event type for builder reset events. Events of this type are generated each time the builder's
    043     * {@code resetResult()} method is called.
    044     */
    045    public static final EventType<ConfigurationBuilderEvent> RESET = new EventType<>(ANY, "RESET");
    046
    047    /**
    048     * The specific event type for configuration request events. Events of this type are generated each time the builder's
    049     * {@code getConfiguration()} method is called (before the managed configuration is actually accessed and the lock is
    050     * acquired). This gives listeners the opportunity to perform some checks which may invalidate the configuration, for example
    051     * trigger a reload check. <strong>Note:</strong> A listener must not call the builder's {@code getConfiguration()}
    052     * method - this will cause an infinite loop!
    053     *
    054     * @see ConfigurationBuilder#getConfiguration()
    055     */
    056    public static final EventType<ConfigurationBuilderEvent> CONFIGURATION_REQUEST = new EventType<>(ANY, "CONFIGURATION_REQUEST");
    057
    058    /**
    059     * Creates a new instance of {@code ConfigurationBuilderEvent} and sets basic properties.
    060     *
    061     * @param source the {@code ConfigurationBuilder} object which triggered this event (must not be <strong>null</strong>)
    062     * @param evType the type of this event (must not be <strong>null</strong>)
    063     * @throws IllegalArgumentException if a required parameter is null
    064     */
    065    public ConfigurationBuilderEvent(final ConfigurationBuilder<?> source, final EventType<? extends ConfigurationBuilderEvent> evType) {
    066        super(source, evType);
    067    }
    068
    069    /**
    070     * Gets the source of this event as a {@code ConfigurationBuilder}.
    071     *
    072     * @return the {@code ConfigurationBuilder} which generated this event
    073     */
    074    @Override
    075    public ConfigurationBuilder<?> getSource() {
    076        return (ConfigurationBuilder<?>) super.getSource();
    077    }
    078}