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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.functor.core.composite;
18  
19  import java.io.Serializable;
20  
21  import org.apache.commons.functor.BinaryPredicate;
22  
23  /**
24   * {@link #test Tests} to the logical inverse
25   * of some other predicate.
26   * <p>
27   * Note that although this class implements
28   * {@link Serializable}, a given instance will
29   * only be truly <code>Serializable</code> if the
30   * underlying functor is.  Attempts to serialize
31   * an instance whose delegate is not
32   * <code>Serializable</code> will result in an exception.
33   * </p>
34   * @version $Revision: 1156320 $ $Date: 2011-08-10 21:14:50 +0200 (Wed, 10 Aug 2011) $
35   * @author Rodney Waldhoff
36   */
37  public final class BinaryNot<L, R> implements BinaryPredicate<L, R>, Serializable {
38      /**
39       * serialVersionUID declaration.
40       */
41      private static final long serialVersionUID = -3488974286912054737L;
42      // attributes
43      // ------------------------------------------------------------------------
44      private final BinaryPredicate<? super L, ? super R> predicate;
45  
46      // constructor
47      // ------------------------------------------------------------------------
48      /**
49       * Create a new BinaryNot.
50       * @param predicate BinaryPredicate to negate
51       */
52      public BinaryNot(BinaryPredicate<? super L, ? super R> predicate) {
53          if (predicate == null) {
54              throw new IllegalArgumentException("BinaryPredicate argument was null");
55          }
56          this.predicate = predicate;
57      }
58  
59      // predicate interface
60      // ------------------------------------------------------------------------
61      /**
62       * {@inheritDoc}
63       */
64      public boolean test(L left, R right) {
65          return !(predicate.test(left, right));
66      }
67  
68      /**
69       * {@inheritDoc}
70       */
71      public boolean equals(Object that) {
72          return that == this || (that instanceof BinaryNot<?, ?> && equals((BinaryNot<?, ?>) that));
73      }
74  
75      /**
76       * Learn whether another BinaryNot is equal to this.
77       * @param that BinaryNot to test
78       * @return boolean
79       */
80      public boolean equals(BinaryNot<?, ?> that) {
81          return null != that && (null == predicate ? null == that.predicate : predicate.equals(that.predicate));
82      }
83  
84      /**
85       * {@inheritDoc}
86       */
87      public int hashCode() {
88          int hash = "BinaryNot".hashCode();
89          if (null != predicate) {
90              hash ^= predicate.hashCode();
91          }
92          return hash;
93      }
94  
95      /**
96       * {@inheritDoc}
97       */
98      public String toString() {
99          return "BinaryNot<" + predicate + ">";
100     }
101 
102     // static
103     // ------------------------------------------------------------------------
104     /**
105      * Negate a BinaryPredicate.
106      * @param that BinaryPredicate to negate
107      * @return BinaryPredicate
108      */
109     public static <L, R> BinaryPredicate<L, R> not(BinaryPredicate<? super L, ? super R> that) {
110         return null == that ? null : new BinaryNot<L, R>(that);
111     }
112 
113 }