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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.commons.collections4.sequence;
18  
19  /**
20   * Command representing the keeping of one object present in both sequences.
21   * <p>
22   * When one object of the first sequence <code>equals</code> another objects in
23   * the second sequence at the right place, the {@link EditScript edit script}
24   * transforming the first sequence into the second sequence uses an instance of
25   * this class to represent the keeping of this object. The objects embedded in
26   * these type of commands always come from the first sequence.
27   * </p>
28   *
29   * @see SequencesComparator
30   * @see EditScript
31   *
32   * @since 4.0
33   */
34  public class KeepCommand<T> extends EditCommand<T> {
35  
36      /**
37       * Simple constructor. Creates a new instance of KeepCommand
38       *
39       * @param object  the object belonging to both sequences (the object is a
40       *   reference to the instance in the first sequence which is known
41       *   to be equal to an instance in the second sequence)
42       */
43      public KeepCommand(final T object) {
44          super(object);
45      }
46  
47      /**
48       * Accept a visitor. When a <code>KeepCommand</code> accepts a visitor, it
49       * calls its {@link CommandVisitor#visitKeepCommand visitKeepCommand} method.
50       *
51       * @param visitor  the visitor to be accepted
52       */
53      @Override
54      public void accept(final CommandVisitor<T> visitor) {
55          visitor.visitKeepCommand(getObject());
56      }
57  }