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1   package org.apache.maven.repository.legacy.resolver.conflict;
2   
3   /*
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *  http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.
20   */
21  
22  import org.apache.maven.artifact.resolver.ResolutionNode;
23  import org.apache.maven.artifact.versioning.ArtifactVersion;
24  import org.apache.maven.artifact.versioning.OverConstrainedVersionException;
25  import org.codehaus.plexus.component.annotations.Component;
26  
27  /**
28   * Resolves conflicting artifacts by always selecting the <em>oldest</em> declaration. Oldest is defined as the
29   * declaration whose version is less according to <code>ArtifactVersion.compareTo</code>.
30   *
31   * @author <a href="mailto:markhobson@gmail.com">Mark Hobson</a>
32   * @see ArtifactVersion#compareTo
33   * @since 3.0
34   */
35  @Component( role = ConflictResolver.class, hint = "oldest" )
36  public class OldestConflictResolver
37      implements ConflictResolver
38  {
39      // ConflictResolver methods -----------------------------------------------
40  
41      /*
42      * @see org.apache.maven.artifact.resolver.conflict.ConflictResolver#resolveConflict(org.apache.maven.artifact.resolver.ResolutionNode,
43      *      org.apache.maven.artifact.resolver.ResolutionNode)
44      */
45  
46      public ResolutionNode resolveConflict( ResolutionNode node1, ResolutionNode node2 )
47      {
48          try
49          {
50              ArtifactVersion version1 = node1.getArtifact().getSelectedVersion();
51              ArtifactVersion version2 = node2.getArtifact().getSelectedVersion();
52  
53              return version1.compareTo( version2 ) <= 0 ? node1 : node2;
54          }
55          catch ( OverConstrainedVersionException exception )
56          {
57              // TODO: log message or throw exception?
58  
59              return null;
60          }
61      }
62  }