File D:\maven-qcr-plugin-testsunitaires\qcr4java\jenkins-master\target\site\qc\core\src\main\java\hudson\Lookup.java.html

1 /*
2 * The MIT License
3 *
4 * Copyright (c) 2010, Kohsuke Kawaguchi
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 * THE SOFTWARE.
23 */
24
25 package hudson;
26
27 import java.util.concurrent.ConcurrentHashMap;
28
29 /**
30 * Type-safe instance map.
31 *
32 * @author Kohsuke Kawaguchi
33 */
34 public class Lookup {
35 private final ConcurrentHashMap<Class,Object> data = new ConcurrentHashMap<Class,Object>();
36
37 public <T> T get(Class<T> type) {
38 return type.cast(data.get(type));
39 }
40
41 public <T> T set(Class<T> type, T instance) {
42 return type.cast(data.put(type,instance));
43 }
44
45 /**
46 * Overwrites the value only if the current value is null.
47 *
48 * @return
49 * If the value was null, return the {@code instance} value.
50 * Otherwise return the current value, which is non-null.
51 */
52 public <T> T setIfNull(Class<T> type, T instance) {
53 Object o = data.putIfAbsent(type, instance);
54 if (o!=null) return type.cast(o);
55 return instance;
56 }
57 }
58