Mercurial > hg > truffle
view graal/com.oracle.max.base/src/com/sun/max/collect/HashIdentity.java @ 4213:e4cfa571d8c4
Do not emit stack-to-stack moves.
author | Christian Wimmer <Christian.Wimmer@Oracle.com> |
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date | Tue, 03 Jan 2012 18:47:27 -0800 |
parents | bc8527f3071c |
children |
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/* * Copyright (c) 2007, 2011, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package com.sun.max.collect; import com.sun.max.*; /** * Defines the semantics of key comparison in a {@linkplain HashMapping hash based data structure} where reference * identity is used for {@linkplain #equivalent(Object, Object) equivalence} and the hash code are obtained from * {@link System#identityHashCode(Object)}. There is a {@linkplain #instance(Class) singleton} instance of this class. */ public final class HashIdentity<T> implements HashEquivalence<T> { private HashIdentity() { } public boolean equivalent(T object1, T object2) { return object1 == object2; } public int hashCode(T object) { if (object == null) { return 0; } return System.identityHashCode(object); } private static final HashIdentity identity = new HashIdentity<>(); public static <T> HashIdentity<T> instance(Class<HashIdentity<T>> type) { return Utils.cast(type, identity); } }