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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.toolchain.model;
20  
21  import java.io.Serializable;
22  
23  import static java.util.Objects.requireNonNull;
24  
25  public abstract class BaseObject implements Serializable, Cloneable {
26      protected transient ChildrenTracking childrenTracking;
27  
28      protected Object delegate;
29  
30      public BaseObject() {}
31  
32      public BaseObject(Object delegate, BaseObject parent) {
33          this.delegate = requireNonNull(delegate, "delegate cannot be null");
34          this.childrenTracking = parent != null ? parent::replace : null;
35      }
36  
37      public BaseObject(Object delegate, ChildrenTracking parent) {
38          this.delegate = requireNonNull(delegate, "delegate cannot be null");
39          this.childrenTracking = parent;
40      }
41  
42      public Object getDelegate() {
43          return delegate;
44      }
45  
46      public void update(Object newDelegate) {
47          if (delegate != newDelegate) {
48              if (childrenTracking != null) {
49                  childrenTracking.replace(delegate, newDelegate);
50              }
51              delegate = newDelegate;
52          }
53      }
54  
55      protected boolean replace(Object oldDelegate, Object newDelegate) {
56          return false;
57      }
58  
59      @FunctionalInterface
60      protected interface ChildrenTracking {
61          boolean replace(Object oldDelegate, Object newDelegate);
62      }
63  }