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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.api;
20  
21  import java.util.List;
22  import java.util.Optional;
23  import java.util.function.Predicate;
24  import java.util.stream.Stream;
25  
26  import org.apache.maven.api.annotations.Experimental;
27  import org.apache.maven.api.annotations.Immutable;
28  import org.apache.maven.api.annotations.Nonnull;
29  
30  /**
31   * Represents a dependency node within a Maven project's dependency collector.
32   *
33   * @since 4.0
34   * @see org.apache.maven.api.services.DependencyCollectorResult#getRoot()
35   */
36  @Experimental
37  @Immutable
38  public interface Node {
39  
40      /**
41       * @return dependency for this node
42       */
43      Dependency getDependency();
44  
45      /**
46       * Gets the child nodes of this node.
47       *
48       * @return the child nodes of this node, never {@code null}
49       */
50      @Nonnull
51      List<Node> getChildren();
52  
53      /**
54       * @return repositories of this node
55       */
56      @Nonnull
57      List<RemoteRepository> getRemoteRepositories();
58  
59      /**
60       * The repository where this artifact has been downloaded from.
61       */
62      @Nonnull
63      Optional<RemoteRepository> getRepository();
64  
65      /**
66       * Traverses this node and potentially its children using the specified visitor.
67       *
68       * @param visitor the visitor to call back, must not be {@code null}
69       * @return {@code true} to visit siblings nodes of this node as well, {@code false} to skip siblings
70       */
71      boolean accept(@Nonnull NodeVisitor visitor);
72  
73      /**
74       * Returns a new tree starting at this node, filtering the children.
75       * Note that this node will not be filtered and only the children
76       * and its descendant will be checked.
77       *
78       * @param filter the filter to apply
79       * @return a new filtered graph
80       */
81      Node filter(Predicate<Node> filter);
82  
83      /**
84       * Returns a string representation of this dependency node.
85       *
86       * @return the string representation
87       */
88      String asString();
89  
90      /**
91       * Obtain a Stream containing this node and all its descendant.
92       *
93       * @return a stream containing this node and its descendant
94       */
95      @Nonnull
96      default Stream<Node> stream() {
97          return Stream.concat(Stream.of(this), getChildren().stream().flatMap(Node::stream));
98      }
99  }