1 /*
2 * *************************************************************************************************************************************************************
3 *
4 * TheseFoolishThings: Miscellaneous utilities
5 * http://tidalwave.it/projects/thesefoolishthings
6 *
7 * Copyright (C) 2009 - 2025 by Tidalwave s.a.s. (http://tidalwave.it)
8 *
9 * *************************************************************************************************************************************************************
10 *
11 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
12 * You may obtain a copy of the License at
13 *
14 * http://www.apache.org/licenses/LICENSE-2.0
15 *
16 * 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
17 * CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
18 *
19 * *************************************************************************************************************************************************************
20 *
21 * git clone https://bitbucket.org/tidalwave/thesefoolishthings-src
22 * git clone https://github.com/tidalwave-it/thesefoolishthings-src
23 *
24 * *************************************************************************************************************************************************************
25 */
26 package it.tidalwave.util;
27
28 import javax.annotation.Nonnull;
29 import java.util.Optional;
30 import java.util.concurrent.ConcurrentHashMap;
31
32 /***************************************************************************************************************************************************************
33 *
34 * A specialisation of {@link ConcurrentHashMap} with {@link Optional} support.
35 *
36 * @param <K> the type of the key
37 * @param <V> the type of the value
38 *
39 * @since 3.1-ALPHA-2
40 * @author Fabrizio Giudici
41 *
42 **************************************************************************************************************************************************************/
43 public class ConcurrentHashMapWithOptionals<K, V> extends ConcurrentHashMap<K, V>
44 {
45 private static final long serialVersionUID = -1771492882183193296L;
46
47 /***********************************************************************************************************************************************************
48 * If the map doesn't contain the given key, put the new pair(key, value), and return the key itself. Otherwise,
49 * do nothing and return an empty {@link Optional}. The map manipulation is atomically performed by calling
50 * {@link #putIfAbsent(java.lang.Object, java.lang.Object)}.
51 *
52 * If {@code optionalKey} is empty, do nothing and return nothing.
53 *
54 * @param optionalKey the key
55 * @param value the value
56 * @return the new key, or nothing
57 **********************************************************************************************************************************************************/
58 @Nonnull
59 public Optional<K> putIfAbsentAndGetNewKey (@Nonnull final Optional<? extends K> optionalKey, @Nonnull final V value)
60 {
61 return optionalKey.flatMap(key -> putIfAbsentAndGetNewKey(key, value));
62 }
63
64 /***********************************************************************************************************************************************************
65 * If the map doesn't contain the given key, put the new pair(key, value), and return the key itself. Otherwise,
66 * do nothing and return an empty {@link Optional}. The map manipulation is atomically performed by calling
67 * {@link #putIfAbsent(java.lang.Object, java.lang.Object)}.
68 *
69 * @param key the key
70 * @param value the value
71 * @return the new key, or nothing
72 **********************************************************************************************************************************************************/
73 @Nonnull
74 public Optional<K> putIfAbsentAndGetNewKey (@Nonnull final K key, @Nonnull final V value)
75 {
76 return (putIfAbsent(key, value) == null) ? Optional.of(key) : Optional.empty();
77 }
78 }