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.util.graph.visitor; 020 021import java.util.function.Consumer; 022 023import org.eclipse.aether.ConfigurationProperties; 024import org.eclipse.aether.graph.DependencyFilter; 025import org.eclipse.aether.graph.DependencyNode; 026 027/** 028 * Processes dependency graph by traversing the graph in postorder. This visitor visits each node exactly once 029 * regardless how many paths within the dependency graph lead to the node such that the resulting node sequence is 030 * free of duplicates. 031 * <p> 032 * <strong>Instances of this class cannot be embedded into {@link FilteringDependencyVisitor}</strong>, pass in the 033 * filter {@link DependencyFilter} into constructor instead. 034 * 035 * @see NodeListGenerator 036 * @since 2.0.0 037 */ 038public final class PostorderDependencyNodeConsumerVisitor extends AbstractDependencyNodeConsumerVisitor { 039 040 public static final String NAME = ConfigurationProperties.REPOSITORY_SYSTEM_DEPENDENCY_VISITOR_POSTORDER; 041 042 private final Stack<Boolean> visits; 043 044 /** 045 * Creates a new postorder list generator. 046 */ 047 public PostorderDependencyNodeConsumerVisitor(Consumer<DependencyNode> nodeConsumer) { 048 this(nodeConsumer, null); 049 } 050 051 /** 052 * Creates a new postorder list generator. 053 * 054 * @since 2.0.12 055 */ 056 public PostorderDependencyNodeConsumerVisitor(Consumer<DependencyNode> nodeConsumer, DependencyFilter filter) { 057 super(nodeConsumer, filter); 058 visits = new Stack<>(); 059 } 060 061 @Override 062 protected boolean doVisitEnter(DependencyNode node) { 063 boolean visited = !setVisited(node); 064 visits.push(visited); 065 return !visited; 066 } 067 068 @Override 069 protected boolean doVisitLeave(DependencyNode node) { 070 Boolean visited = visits.pop(); 071 if (visited) { 072 return true; 073 } 074 if (acceptNode(node)) { 075 consumeNode(node); 076 } 077 return true; 078 } 079}