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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.functors;
18  
19  import java.io.Serializable;
20  
21  import org.apache.commons.collections4.Equator;
22  import org.apache.commons.collections4.Predicate;
23  
24  /**
25   * Predicate implementation that returns true if the input is the same object
26   * as the one stored in this predicate by equals.
27   *
28   * @since 3.0
29   */
30  public final class EqualPredicate<T> implements Predicate<T>, Serializable {
31  
32      /** Serial version UID */
33      private static final long serialVersionUID = 5633766978029907089L;
34  
35      /** The value to compare to */
36      private final T iValue;
37  
38      /** The equator to use for comparison */
39      private final Equator<T> equator;
40  
41      /**
42       * Factory to create the predicate.
43       *
44       * @param <T> the type that the predicate queries
45       * @param object  the object to compare to
46       * @return the predicate
47       */
48      public static <T> Predicate<T> equalPredicate(final T object) {
49          if (object == null) {
50              return NullPredicate.nullPredicate();
51          }
52          return new EqualPredicate<>(object);
53      }
54  
55      /**
56       * Factory to create the identity predicate.
57       *
58       * @param <T> the type that the predicate queries
59       * @param object  the object to compare to
60       * @param equator  the equator to use for comparison
61       * @return the predicate
62       * @since 4.0
63       */
64      public static <T> Predicate<T> equalPredicate(final T object, final Equator<T> equator) {
65          if (object == null) {
66              return NullPredicate.nullPredicate();
67          }
68          return new EqualPredicate<>(object, equator);
69      }
70  
71      /**
72       * Constructor that performs no validation.
73       * Use <code>equalPredicate</code> if you want that.
74       *
75       * @param object  the object to compare to
76       */
77      public EqualPredicate(final T object) {
78          // do not use the DefaultEquator to keep backwards compatibility
79          // the DefaultEquator returns also true if the two object references are equal
80          this(object, null);
81      }
82  
83      /**
84       * Constructor that performs no validation.
85       * Use <code>equalPredicate</code> if you want that.
86       *
87       * @param object  the object to compare to
88       * @param equator  the equator to use for comparison
89       * @since 4.0
90       */
91      public EqualPredicate(final T object, final Equator<T> equator) {
92          super();
93          iValue = object;
94          this.equator = equator;
95      }
96  
97      /**
98       * Evaluates the predicate returning true if the input equals the stored value.
99       *
100      * @param object  the input object
101      * @return true if input object equals stored value
102      */
103     @Override
104     public boolean evaluate(final T object) {
105         if (equator != null) {
106             return equator.equate(iValue, object);
107         }
108         return iValue.equals(object);
109     }
110 
111     /**
112      * Gets the value.
113      *
114      * @return the value
115      * @since 3.1
116      */
117     public Object getValue() {
118         return iValue;
119     }
120 
121 }