001package org.eclipse.aether.graph;
002
003/*
004 * Licensed to the Apache Software Foundation (ASF) under one
005 * or more contributor license agreements.  See the NOTICE file
006 * distributed with this work for additional information
007 * regarding copyright ownership.  The ASF licenses this file
008 * to you under the Apache License, Version 2.0 (the
009 * "License"); you may not use this file except in compliance
010 * with the License.  You may obtain a copy of the License at
011 * 
012 *  http://www.apache.org/licenses/LICENSE-2.0
013 * 
014 * Unless required by applicable law or agreed to in writing,
015 * software distributed under the License is distributed on an
016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017 * KIND, either express or implied.  See the License for the
018 * specific language governing permissions and limitations
019 * under the License.
020 */
021
022/**
023 * A visitor for nodes of the dependency graph.
024 * 
025 * @see DependencyNode#accept(DependencyVisitor)
026 */
027public interface DependencyVisitor
028{
029
030    /**
031     * Notifies the visitor of a node visit before its children have been processed.
032     * 
033     * @param node The dependency node being visited, must not be {@code null}.
034     * @return {@code true} to visit child nodes of the specified node as well, {@code false} to skip children.
035     */
036    boolean visitEnter( DependencyNode node );
037
038    /**
039     * Notifies the visitor of a node visit after its children have been processed. Note that this method is always
040     * invoked regardless whether any children have actually been visited.
041     * 
042     * @param node The dependency node being visited, must not be {@code null}.
043     * @return {@code true} to visit siblings nodes of the specified node as well, {@code false} to skip siblings.
044     */
045    boolean visitLeave( DependencyNode node );
046
047}