1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
|
/*
* Copyright (C) 2008 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.common.collect;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.CollectPreconditions.checkEntryNotNull;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.errorprone.annotations.concurrent.LazyInit;
import com.google.j2objc.annotations.RetainedWith;
import java.util.function.BiConsumer;
import javax.annotation.CheckForNull;
/**
* Implementation of {@link ImmutableMap} with exactly one entry.
*
* @author Jesse Wilson
* @author Kevin Bourrillion
*/
@GwtCompatible(serializable = true, emulated = true)
@SuppressWarnings("serial") // uses writeReplace(), not default serialization
@ElementTypesAreNonnullByDefault
final class SingletonImmutableBiMap<K, V> extends ImmutableBiMap<K, V> {
final transient K singleKey;
final transient V singleValue;
SingletonImmutableBiMap(K singleKey, V singleValue) {
checkEntryNotNull(singleKey, singleValue);
this.singleKey = singleKey;
this.singleValue = singleValue;
this.inverse = null;
}
private SingletonImmutableBiMap(K singleKey, V singleValue, ImmutableBiMap<V, K> inverse) {
this.singleKey = singleKey;
this.singleValue = singleValue;
this.inverse = inverse;
}
@Override
@CheckForNull
public V get(@CheckForNull Object key) {
return singleKey.equals(key) ? singleValue : null;
}
@Override
public int size() {
return 1;
}
@Override
public void forEach(BiConsumer<? super K, ? super V> action) {
checkNotNull(action).accept(singleKey, singleValue);
}
@Override
public boolean containsKey(@CheckForNull Object key) {
return singleKey.equals(key);
}
@Override
public boolean containsValue(@CheckForNull Object value) {
return singleValue.equals(value);
}
@Override
boolean isPartialView() {
return false;
}
@Override
ImmutableSet<Entry<K, V>> createEntrySet() {
return ImmutableSet.of(Maps.immutableEntry(singleKey, singleValue));
}
@Override
ImmutableSet<K> createKeySet() {
return ImmutableSet.of(singleKey);
}
@CheckForNull private final transient ImmutableBiMap<V, K> inverse;
@LazyInit @RetainedWith @CheckForNull private transient ImmutableBiMap<V, K> lazyInverse;
@Override
public ImmutableBiMap<V, K> inverse() {
if (inverse != null) {
return inverse;
} else {
// racy single-check idiom
ImmutableBiMap<V, K> result = lazyInverse;
if (result == null) {
return lazyInverse = new SingletonImmutableBiMap<>(singleValue, singleKey, this);
} else {
return result;
}
}
}
// redeclare to help optimizers with b/310253115
@SuppressWarnings("RedundantOverride")
@Override
@J2ktIncompatible // serialization
@GwtIncompatible // serialization
Object writeReplace() {
return super.writeReplace();
}
}
|
