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