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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.plugins.dependency.tree;
20  
21  import java.io.IOException;
22  import java.io.UncheckedIOException;
23  import java.io.Writer;
24  import java.util.List;
25  
26  import org.apache.maven.shared.dependency.graph.DependencyNode;
27  import org.apache.maven.shared.dependency.graph.traversal.DependencyNodeVisitor;
28  
29  /**
30   * A dependency node visitor that serializes visited nodes to <a href="https://en.wikipedia.org/wiki/DOT_language">DOT
31   * format</a>
32   *
33   * @author <a href="mailto:pi.songs@gmail.com">Pi Song</a>
34   * @since 2.1
35   */
36  public class DOTDependencyNodeVisitor extends AbstractSerializingVisitor implements DependencyNodeVisitor {
37  
38      /**
39       * Constructor.
40       *
41       * @param writer the writer to write to
42       */
43      public DOTDependencyNodeVisitor(Writer writer) {
44          super(writer);
45      }
46  
47      /**
48       * {@inheritDoc}
49       */
50      @Override
51      public boolean visit(DependencyNode node) {
52          try {
53              if (node.getParent() == null || node.getParent() == node) {
54                  writer.write("digraph \"" + node.toNodeString() + "\" { " + System.lineSeparator());
55                  writer.flush();
56              }
57  
58              // Generate "currentNode -> Child" lines
59  
60              List<DependencyNode> children = node.getChildren();
61  
62              for (DependencyNode child : children) {
63                  writer.write("\t\"" + node.toNodeString() + "\" -> \"" + child.toNodeString() + "\" ; "
64                          + System.lineSeparator());
65              }
66              writer.flush();
67          } catch (IOException e) {
68              throw new UncheckedIOException("Failed to write DOT format output", e);
69          }
70  
71          return true;
72      }
73  
74      /**
75       * {@inheritDoc}
76       */
77      @Override
78      public boolean endVisit(DependencyNode node) {
79          try {
80              if (node.getParent() == null || node.getParent() == node) {
81                  writer.write(" } " + System.lineSeparator());
82                  writer.flush();
83              }
84          } catch (IOException e) {
85              throw new UncheckedIOException("Failed to write DOT format output", e);
86          }
87          return true;
88      }
89  }