1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.eclipse.aether.util.graph.visitor;
20
21 import java.util.function.Consumer;
22
23 import org.eclipse.aether.ConfigurationProperties;
24 import org.eclipse.aether.graph.DependencyFilter;
25 import org.eclipse.aether.graph.DependencyNode;
26
27 /**
28 * Processes dependency graph by traversing the graph in preorder. This visitor visits each node exactly once
29 * regardless how many paths within the dependency graph lead to the node such that the resulting node sequence is
30 * free of duplicates.
31 * <p>
32 * <strong>Instances of this class cannot be embedded into {@link FilteringDependencyVisitor}</strong>, pass in the
33 * filter {@link DependencyFilter} into constructor instead.
34 *
35 * @see NodeListGenerator
36 * @since 2.0.0
37 */
38 public final class PreorderDependencyNodeConsumerVisitor extends AbstractDependencyNodeConsumerVisitor {
39
40 public static final String NAME = ConfigurationProperties.REPOSITORY_SYSTEM_DEPENDENCY_VISITOR_PREORDER;
41
42 /**
43 * Creates a new preorder list generator.
44 */
45 public PreorderDependencyNodeConsumerVisitor(Consumer<DependencyNode> nodeConsumer) {
46 this(nodeConsumer, null);
47 }
48
49 /**
50 * Creates a new preorder list generator.
51 *
52 * @since 2.0.12
53 */
54 public PreorderDependencyNodeConsumerVisitor(Consumer<DependencyNode> nodeConsumer, DependencyFilter filter) {
55 super(nodeConsumer, filter);
56 }
57
58 @Override
59 protected boolean doVisitEnter(DependencyNode node) {
60 if (!setVisited(node)) {
61 return false;
62 }
63 if (acceptNode(node)) {
64 consumeNode(node);
65 }
66 return true;
67 }
68
69 @Override
70 protected boolean doVisitLeave(DependencyNode node) {
71 return true;
72 }
73 }