Coverage Summary for Class: FunctionalEquivalence (com.google.common.base)

1 /*
2  * Copyright (C) 2011 The Guava Authors
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5  * in compliance with the License. You may obtain a copy of the License at
6  *
7  * http://www.apache.org/licenses/LICENSE-2.0
8  *
9  * Unless required by applicable law or agreed to in writing, software distributed under the License
10  * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
11  * or implied. See the License for the specific language governing permissions and limitations under
12  * the License.
13  */
14 
15 package com.google.common.base;
16 
17 import static com.google.common.base.Preconditions.checkNotNull;
18 
19 import com.google.common.annotations.Beta;
20 import com.google.common.annotations.GwtCompatible;
21 import java.io.Serializable;
22 import javax.annotation.CheckForNull;
23 
24 /**
25  * Equivalence applied on functional result.
26  *
27  * @author Bob Lee
28  * @since 10.0
29  */
30 @Beta
31 @GwtCompatible
32 @ElementTypesAreNonnullByDefault
33 final class FunctionalEquivalence<F, T> extends Equivalence<F> implements Serializable {
34 
35   private static final long serialVersionUID = 0;
36 
37   private final Function<? super F, ? extends T> function;
38   private final Equivalence<T> resultEquivalence;
39 
40   FunctionalEquivalence(
41       Function<? super F, ? extends T> function, Equivalence<T> resultEquivalence) {
42     this.function = checkNotNull(function);
43     this.resultEquivalence = checkNotNull(resultEquivalence);
44   }
45 
46   @Override
47   protected boolean doEquivalent(F a, F b) {
48     return resultEquivalence.equivalent(function.apply(a), function.apply(b));
49   }
50 
51   @Override
52   protected int doHash(F a) {
53     return resultEquivalence.hash(function.apply(a));
54   }
55 
56   @Override
57   public boolean equals(@CheckForNull Object obj) {
58     if (obj == this) {
59       return true;
60     }
61     if (obj instanceof FunctionalEquivalence) {
62       FunctionalEquivalence<?, ?> that = (FunctionalEquivalence<?, ?>) obj;
63       return function.equals(that.function) && resultEquivalence.equals(that.resultEquivalence);
64     }
65     return false;
66   }
67 
68   @Override
69   public int hashCode() {
70     return Objects.hashCode(function, resultEquivalence);
71   }
72 
73   @Override
74   public String toString() {
75     return resultEquivalence + ".onResultOf(" + function + ")";
76   }
77 }