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.apache.maven.shared.dependency.graph.traversal;
20
21 import java.util.ArrayList;
22 import java.util.Stack;
23
24 import org.apache.maven.shared.dependency.graph.DependencyNode;
25 import org.apache.maven.shared.dependency.graph.internal.DefaultDependencyNode;
26
27 /**
28 * A dependency node visitor that clones visited nodes into a new dependency tree. This can be used in conjunction with
29 * a dependency node filter to construct subtrees.
30 *
31 * @author <a href="mailto:markhobson@gmail.com">Mark Hobson</a>
32 */
33 public class BuildingDependencyNodeVisitor implements DependencyNodeVisitor {
34 // fields -----------------------------------------------------------------
35
36 /**
37 * The dependency node visitor to apply on the resultant dependency tree, or <code>null</code> for none.
38 */
39 private final DependencyNodeVisitor visitor;
40
41 /**
42 * The resultant tree parent nodes for the currently visited node.
43 */
44 private final Stack<DependencyNode> parentNodes;
45
46 /**
47 * The root node of the resultant tree.
48 */
49 private DependencyNode rootNode;
50
51 // constructors -----------------------------------------------------------
52
53 /**
54 * Creates a dependency node visitor that clones visited nodes into a new dependency tree.
55 */
56 public BuildingDependencyNodeVisitor() {
57 this(null);
58 }
59
60 /**
61 * Creates a dependency node visitor that clones visited nodes into a new dependency tree, and then applies the
62 * specified dependency node visitor on the resultant dependency tree.
63 *
64 * @param visitor the dependency node visitor to apply on the resultant dependency tree, or <code>null</code> for
65 * none
66 */
67 public BuildingDependencyNodeVisitor(DependencyNodeVisitor visitor) {
68 this.visitor = visitor;
69
70 parentNodes = new Stack<>();
71 }
72
73 // DependencyNodeVisitor methods ------------------------------------------
74
75 /**
76 * {@inheritDoc}
77 */
78 @Override
79 public boolean visit(DependencyNode node) {
80 // clone the node
81 DefaultDependencyNode newNode = new DefaultDependencyNode(
82 parentNodes.isEmpty() ? null : parentNodes.peek(),
83 node.getArtifact(),
84 node.getPremanagedVersion(),
85 node.getPremanagedScope(),
86 node.getVersionConstraint(),
87 node.getOptional(),
88 node.getExclusions());
89 newNode.setChildren(new ArrayList<>());
90
91 if (parentNodes.empty()) {
92 rootNode = newNode;
93 } else {
94 DependencyNode parentNode = parentNodes.peek();
95 parentNode.getChildren().add(newNode);
96 }
97
98 parentNodes.push(newNode);
99
100 return true;
101 }
102
103 /**
104 * {@inheritDoc}
105 */
106 @Override
107 public boolean endVisit(DependencyNode node) {
108 parentNodes.pop();
109
110 // apply the visitor to the resultant tree on the last visit
111 if (parentNodes.empty() && visitor != null) {
112 rootNode.accept(visitor);
113 }
114
115 return true;
116 }
117
118 // public methods ---------------------------------------------------------
119
120 /**
121 * Gets the dependency node visitor that this visitor applies on the resultant dependency tree.
122 *
123 * @return the dependency node visitor, or <code>null</code> for none
124 */
125 public DependencyNodeVisitor getDependencyNodeVisitor() {
126 return visitor;
127 }
128
129 /**
130 * Gets the root node of the resultant dependency tree constructed by this visitor.
131 *
132 * @return the root node, or <code>null</code> if the source tree has not yet been visited
133 */
134 public DependencyNode getDependencyTree() {
135 return rootNode;
136 }
137 }