1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 package org.apache.commons.configuration.tree; 18 19 /** 20 * <p> 21 * Definition of a <em>Visitor</em> interface for a configuration node 22 * structure. 23 * </p> 24 * <p> 25 * The {@code ConfigurationNode} interface defines a {@code visit()}, 26 * which simplifies traversal of a complex node hierarchy. A configuration node 27 * implementation must provide a way of visiting all nodes in the current 28 * hierarchy. This is a typical application of the GoF <em>Visitor</em> 29 * pattern. 30 * </p> 31 * 32 * @since 1.3 33 * @see ConfigurationNode 34 * @author <a 35 * href="http://commons.apache.org/configuration/team-list.html">Commons 36 * Configuration team</a> 37 * @version $Id: ConfigurationNodeVisitor.java 1206463 2011-11-26 15:47:08Z oheger $ 38 */ 39 public interface ConfigurationNodeVisitor 40 { 41 /** 42 * Visits the specified node. This method is called before eventually 43 * existing children of this node are processed. 44 * 45 * @param node the node to be visited 46 */ 47 void visitBeforeChildren(ConfigurationNode node); 48 49 /** 50 * Visits the specified node. This method is called after eventually 51 * existing children of this node have been processed. 52 * 53 * @param node the node to be visited 54 */ 55 void visitAfterChildren(ConfigurationNode node); 56 57 /** 58 * Returns a flag whether the actual visit process should be aborted. This 59 * method allows a visitor implementation to state that it does not need any 60 * further data. It may be used e.g. by visitors that search for a certain 61 * node in the hierarchy. After that node was found, there is no need to 62 * process the remaining nodes, too. 63 * 64 * @return a flag if the visit process should be stopped 65 */ 66 boolean terminate(); 67 }