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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.eclipse.aether.util.graph.transformer;
20  
21  import java.util.Collection;
22  
23  import org.eclipse.aether.RepositoryException;
24  import org.eclipse.aether.util.graph.transformer.ConflictResolver.ConflictContext;
25  import org.eclipse.aether.util.graph.transformer.ConflictResolver.ConflictItem;
26  import org.eclipse.aether.util.graph.transformer.ConflictResolver.OptionalitySelector;
27  
28  /**
29   * An optionality selector for use with {@link ConflictResolver}. In general, this selector only marks a dependency as
30   * optional if all its occurrences are optional. If however a direct dependency is involved, its optional flag is
31   * selected.
32   */
33  public final class SimpleOptionalitySelector extends OptionalitySelector {
34  
35      /**
36       * Creates a new instance of this optionality selector.
37       */
38      public SimpleOptionalitySelector() {}
39  
40      @Override
41      public void selectOptionality(ConflictContext context) throws RepositoryException {
42          boolean optional = chooseEffectiveOptionality(context.getItems());
43          context.setOptional(optional);
44      }
45  
46      private boolean chooseEffectiveOptionality(Collection<ConflictItem> items) {
47          boolean optional = true;
48          for (ConflictItem item : items) {
49              if (item.getDepth() <= 1) {
50                  return item.getDependency().isOptional();
51              }
52              if ((item.getOptionalities() & ConflictItem.OPTIONAL_FALSE) != 0) {
53                  optional = false;
54              }
55          }
56          return optional;
57      }
58  }