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1   package org.codehaus.plexus.metadata.merge.support;
2   
3   /*
4    * The MIT License
5    *
6    * Copyright (c) 2006, The Codehaus
7    *
8    * Permission is hereby granted, free of charge, to any person obtaining a copy of
9    * this software and associated documentation files (the "Software"), to deal in
10   * the Software without restriction, including without limitation the rights to
11   * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
12   * of the Software, and to permit persons to whom the Software is furnished to do
13   * so, subject to the following conditions:
14   *
15   * The above copyright notice and this permission notice shall be included in all
16   * copies or substantial portions of the Software.
17   *
18   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
21   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
23   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
24   * SOFTWARE.
25   */
26  
27  import java.util.Collections;
28  import java.util.List;
29  
30  import org.codehaus.plexus.metadata.merge.MergeException;
31  import org.codehaus.plexus.metadata.merge.MergeStrategy;
32  
33  /**
34   * Collection of available Merge Strategies.<p>
35   * TODO: Revisit and factor {@link Mergeable#merge(Mergeable)} to use a {@link MergeStrategy}.
36   *
37   * @author <a href='mailto:rahul.thakur.xdev@gmail.com'>Rahul Thakur</a>
38   * @version $Id$
39   */
40  public class MergeStrategies
41  {
42      /**
43       * {@link MergeStrategy} implementation wherein the elements are merged
44       * down to the deepest available {@link Mergeable} instance in the DOM tree.
45       */
46      public static final MergeStrategy DEEP = new MergeStrategy()
47      {
48          public void apply( Mergeable dElt, Mergeable rElt )
49              throws MergeException
50          {
51              dElt.merge( rElt );
52          }
53      };
54  
55      /**
56       * {@link MergeStrategy} implementation wherein only the element on
57       * which the merge operation is called is 'merged'. The merge does not
58       * traverse the DOM tree any further.
59       */
60      public static final MergeStrategy SHALLOW = new MergeStrategy()
61      {
62          /**
63           * @throws MergeException
64           * @see org.codehaus.plexus.metadata.merge.MergeStrategy#apply(Mergeable,Mergeable)
65           */
66          public void apply( Mergeable dElt, Mergeable rElt )
67              throws MergeException
68          {
69              AbstractMergeableElement dame = (AbstractMergeableElement) dElt;
70              AbstractMergeableElement rame = (AbstractMergeableElement) rElt;
71  
72              // check if the dominant was in conflict with recessive.
73              List elementNames = dame.getElementNamesForConflictResolution( Collections.EMPTY_LIST );
74  
75              if ( !dame.isRecessiveElementInConflict( rame, elementNames ) )
76              {
77                  // no conflict, simply add recessive to dominant's parent
78                  dame.getElement().addContent( rame.getElement() );
79              }
80          }
81      };
82  }