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1   /*
2    *    Copyright 2009-2023 the original author or authors.
3    *
4    *    Licensed under the Apache License, Version 2.0 (the "License");
5    *    you may not use this file except in compliance with the License.
6    *    You may obtain a copy of the License at
7    *
8    *       https://www.apache.org/licenses/LICENSE-2.0
9    *
10   *    Unless required by applicable law or agreed to in writing, software
11   *    distributed under the License is distributed on an "AS IS" BASIS,
12   *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   *    See the License for the specific language governing permissions and
14   *    limitations under the License.
15   */
16  package org.apache.ibatis.util;
17  
18  import java.util.AbstractMap;
19  import java.util.Map;
20  import java.util.Map.Entry;
21  import java.util.function.Function;
22  
23  public class MapUtil {
24    /**
25     * A temporary workaround for Java 8 specific performance issue JDK-8161372 .<br>
26     * This class should be removed once we drop Java 8 support.
27     *
28     * @see <a href=
29     *      "https://bugs.openjdk.java.net/browse/JDK-8161372">https://bugs.openjdk.java.net/browse/JDK-8161372</a>
30     */
31    public static <K, V> V computeIfAbsent(Map<K, V> map, K key, Function<K, V> mappingFunction) {
32      V value = map.get(key);
33      if (value != null) {
34        return value;
35      }
36      return map.computeIfAbsent(key, mappingFunction);
37    }
38  
39    /**
40     * Map.entry(key, value) alternative for Java 8.
41     */
42    public static <K, V> Entry<K, V> entry(K key, V value) {
43      return new AbstractMap.SimpleImmutableEntry<>(key, value);
44    }
45  
46    private MapUtil() {
47    }
48  }