Mercurial > hg > truffle
comparison graal/com.oracle.max.base/src/com/sun/max/collect/HashEquality.java @ 3733:e233f5660da4
Added Java files from Maxine project.
author | Thomas Wuerthinger <thomas.wuerthinger@oracle.com> |
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date | Sat, 17 Dec 2011 19:59:18 +0100 |
parents | |
children | bc8527f3071c |
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3732:3e2e8b8abdaf | 3733:e233f5660da4 |
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1 /* | |
2 * Copyright (c) 2007, 2011, Oracle and/or its affiliates. All rights reserved. | |
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
4 * | |
5 * This code is free software; you can redistribute it and/or modify it | |
6 * under the terms of the GNU General Public License version 2 only, as | |
7 * published by the Free Software Foundation. | |
8 * | |
9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
12 * version 2 for more details (a copy is included in the LICENSE file that | |
13 * accompanied this code). | |
14 * | |
15 * You should have received a copy of the GNU General Public License version | |
16 * 2 along with this work; if not, write to the Free Software Foundation, | |
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
18 * | |
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
20 * or visit www.oracle.com if you need additional information or have any | |
21 * questions. | |
22 */ | |
23 package com.sun.max.collect; | |
24 | |
25 import com.sun.max.*; | |
26 | |
27 /** | |
28 * Defines the semantics of key comparison in a {@linkplain HashMapping hash based data structure} that delegate to | |
29 * {@link Object#equals(Object)} and {@link Object#hashCode()}. There is a {@linkplain #instance(Class) singleton} | |
30 * instance of this class. | |
31 */ | |
32 public final class HashEquality<T> implements HashEquivalence<T> { | |
33 | |
34 private HashEquality() { | |
35 } | |
36 | |
37 public boolean equivalent(T object1, T object2) { | |
38 if (object1 == null) { | |
39 return object2 == null; | |
40 } | |
41 return object1.equals(object2); | |
42 } | |
43 | |
44 public int hashCode(T object) { | |
45 if (object == null) { | |
46 return 0; | |
47 } | |
48 return object.hashCode(); | |
49 } | |
50 | |
51 private static final HashEquality equality = new HashEquality<Object>(); | |
52 | |
53 public static <T> HashEquality<T> instance(Class<HashEquality<T>> type) { | |
54 return Utils.cast(type, equality); | |
55 } | |
56 } |