Mercurial > hg > truffle
view graal/com.oracle.max.base/src/com/sun/max/collect/HashMapping.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 |
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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 java.util.*; /** * This class provides a skeletal implementation of the {@link Mapping} interface, to minimize the effort required to * implement this interface. * <p> * This class also includes a number of factory methods for creating {@code Mapping} instances with various properties. */ public abstract class HashMapping<K, V> implements Mapping<K, V> { private final HashEquivalence<K> equivalence; /** * Determines if two given keys are equal. * <p> * Subclasses override this method to define equivalence without delegating to a {@link HashEquivalence} object. */ protected boolean equivalent(K key1, K key2) { return equivalence.equivalent(key1, key2); } /** * Computes a hash code for a given key. * <p> * Subclasses override this method to compute a hash code without delegating to a {@link HashEquivalence} object. */ protected int hashCode(K key) { // Don't guard against a negative number here as the caller needs to convert the hash code into a valid index // which will involve range checking anyway return equivalence.hashCode(key); } /** * Creates a hash table. * * @param equivalence * the semantics to be used for comparing keys. If {@code null} is provided, then {@link HashEquality} is * used. */ protected HashMapping(HashEquivalence<K> equivalence) { if (equivalence == null) { final Class<HashEquality<K>> type = null; this.equivalence = HashEquality.instance(type); } else { this.equivalence = equivalence; } } public boolean containsKey(K key) { return get(key) != null; } protected abstract class HashMappingIterable<Type> implements IterableWithLength<Type> { public int size() { return HashMapping.this.length(); } } /** * Gets an iterator over the values in this mapping by looking up each {@linkplain #keys() key}. * <p> * Subclasses will most likely override this method with a more efficient implementation. */ public IterableWithLength<V> values() { return new HashMappingIterable<V>() { private final IterableWithLength<K> keys = keys(); public Iterator<V> iterator() { return new Iterator<V>() { private final Iterator<K> keyIterator = keys.iterator(); public boolean hasNext() { return keyIterator.hasNext(); } public V next() { return get(keyIterator.next()); } public void remove() { throw new UnsupportedOperationException(); } }; } }; } public static <K, V> Mapping<K, V> createMapping(HashEquivalence<K> equivalence) { return new OpenAddressingHashMapping<>(equivalence); } public static <K, V> Mapping<K, V> createIdentityMapping() { final Class<HashIdentity<K>> type = null; return createMapping(HashIdentity.instance(type)); } public static <K, V> Mapping<K, V> createEqualityMapping() { final Class<HashEquality<K>> type = null; return createMapping(HashEquality.instance(type)); } public static <K, V> Mapping<K, V> createVariableMapping(HashEquivalence<K> equivalence) { return new ChainedHashMapping<>(equivalence); } public static <K, V> Mapping<K, V> createVariableIdentityMapping() { final Class<HashIdentity<K>> type = null; return createVariableMapping(HashIdentity.instance(type)); } public static <K, V> Mapping<K, V> createVariableEqualityMapping() { final Class<HashEquality<K>> type = null; return createVariableMapping(HashEquality.instance(type)); } }