    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
    028 * events are derived from this class. This event base class does not define any
    029 * additional properties. However, it defines that the event source must be a
    030 * {@code ConfigurationBuilder}.
    031 * </p>
    032 *
    033 * @since 2.0
    034 */
    035public class ConfigurationBuilderEvent extends Event
    036{
    037    /** The common super type for all events related to configuration builders. */
    038    public static final EventType<ConfigurationBuilderEvent> ANY =
    039            new EventType<>(Event.ANY, "BUILDER");
    040
    041    /**
    042     * The specific event type for builder reset events. Events of this type are
    043     * generated each time the builder's {@code resetResult()} method is called.
    044     */
    045    public static final EventType<ConfigurationBuilderEvent> RESET =
    046            new EventType<>(ANY, "RESET");
    047
    048    /**
    049     * The specific event type for configuration request events. Events of this
    050     * type are generated each time the builder's {@code getConfiguration()}
    051     * method is called (before the managed configuration is actually accessed
    052     * and the lock is acquired). This gives listeners the opportunity to
    053     * perform some checks which may invalidate the configuration, e.g. trigger
    054     * a reload check. <strong>Note:</strong> A listener must not call the
    055     * builder's {@code getConfiguration()} method - this will cause an
    056     * infinite loop!
    057     *
    058     * @see ConfigurationBuilder#getConfiguration()
    059     */
    060    public static final EventType<ConfigurationBuilderEvent> CONFIGURATION_REQUEST =
    061            new EventType<>(ANY,
    062                    "CONFIGURATION_REQUEST");
    063
    064    /**
    065     * Creates a new instance of {@code ConfigurationBuilderEvent} and sets
    066     * basic properties.
    067     *
    068     * @param source the {@code ConfigurationBuilder} object which triggered
    069     *        this event (must not be <b>null</b>)
    070     * @param evType the type of this event (must not be <b>null</b>)
    071     * @throws IllegalArgumentException if a required parameter is null
    072     */
    073    public ConfigurationBuilderEvent(final ConfigurationBuilder<?> source,
    074            final EventType<? extends ConfigurationBuilderEvent> evType)
    075    {
    076        super(source, evType);
    077    }
    078
    079    /**
    080     * Returns the source of this event as a {@code ConfigurationBuilder}.
    081     *
    082     * @return the {@code ConfigurationBuilder} which generated this event
    083     */
    084    @Override
    085    public ConfigurationBuilder<?> getSource()
    086    {
    087        return (ConfigurationBuilder<?>) super.getSource();
    088    }
    089}