001    /* $Id: RuleLoader.java 471661 2006-11-06 08:09:25Z skitching $
002     *
003     * Licensed to the Apache Software Foundation (ASF) under one or more
004     * contributor license agreements.  See the NOTICE file distributed with
005     * this work for additional information regarding copyright ownership.
006     * The ASF licenses this file to You under the Apache License, Version 2.0
007     * (the "License"); you may not use this file except in compliance with
008     * the License.  You may obtain a copy of the License at
009     * 
010     *      http://www.apache.org/licenses/LICENSE-2.0
011     * 
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */ 
018     
019    package org.apache.commons.digester.plugins;
020    
021    import org.apache.commons.digester.Digester;
022    
023    /**
024     * Interface for classes which can dynamically load custom
025     * plugin rules associated with a user's plugin class.
026     * <p>
027     * Each plugin declaration has an associated RuleLoader instance, and that
028     * instance's addRules method is invoked each time the input xml specifies
029     * that an instance of that plugged-in class is to be created.
030     * <p>
031     * This is an abstract class rather than an interface in order to make
032     * it possible to enhance this class in future without breaking binary
033     * compatibility; it is possible to add methods to an abstract class, but
034     * not to an interface. 
035     *
036     * @since 1.6
037     */
038    
039    public abstract class RuleLoader {
040        
041        /**
042         * Configures the digester with custom rules for some plugged-in
043         * class.
044         * <p>
045         * This method is invoked when the start of an xml tag is encountered
046         * which maps to a PluginCreateRule. Any rules added here are removed
047         * from the digester when the end of that xml tag is encountered.
048         */
049        public abstract void addRules(Digester d, String path) throws PluginException;
050    }