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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.collection;
20  
21  import org.eclipse.aether.graph.Dependency;
22  
23  /**
24   * Applies dependency management to the dependencies of a dependency node.
25   * <p>
26   * <strong>Note:</strong> Implementations must be stateless.
27   * <p>
28   * <em>Warning:</em> This hook is called from a hot spot and therefore implementations should pay attention to
29   * performance. Among others, implementations should provide a semantic {@link Object#equals(Object) equals()} method.
30   *
31   * @see org.eclipse.aether.RepositorySystemSession#getDependencyManager()
32   * @see org.eclipse.aether.RepositorySystem#collectDependencies(org.eclipse.aether.RepositorySystemSession,
33   *      CollectRequest)
34   */
35  public interface DependencyManager {
36  
37      /**
38       * Applies dependency management to the specified dependency.
39       *
40       * @param dependency The dependency to manage, must not be {@code null}.
41       * @return The management update to apply to the dependency or {@code null} if the dependency is not managed at all.
42       */
43      DependencyManagement manageDependency(Dependency dependency);
44  
45      /**
46       * Derives a dependency manager for the specified collection context. When calculating the child manager,
47       * implementors are strongly advised to simply return the current instance if nothing changed to help save memory.
48       *
49       * @param context The dependency collection context, must not be {@code null}.
50       * @return The dependency manager for the dependencies of the target node or {@code null} if dependency management
51       *         should no longer be applied.
52       */
53      DependencyManager deriveChildManager(DependencyCollectionContext context);
54  }