| /* | |
| * Copyright (c) 2004, 2023, 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. Oracle designates this | |
| * particular file as subject to the "Classpath" exception as provided | |
| * by Oracle in the LICENSE file that accompanied this code. | |
| * | |
| * 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 sun.util; | |
| import java.util.Iterator; | |
| import java.util.Map; | |
| import java.util.Set; | |
| import java.util.AbstractMap; | |
| import java.util.AbstractSet; | |
| import java.util.NoSuchElementException; | |
| /** | |
| * A precomputed hash map. | |
| * | |
| * <p> Subclasses of this class are of the following form: | |
| * | |
| * <blockquote><pre> | |
| * class FooMap | |
| * extends sun.util.PreHashedMap<String> | |
| * { | |
| * | |
| * private FooMap() { | |
| * super(ROWS, SIZE, SHIFT, MASK); | |
| * } | |
| * | |
| * protected void init(Object[] ht) { | |
| * ht[0] = new Object[] { "key-1", value_1 }; | |
| * ht[1] = new Object[] { "key-2", value_2, | |
| * new Object { "key-3", value_3 } }; | |
| * ... | |
| * } | |
| * | |
| * }</pre></blockquote> | |
| * | |
| * <p> The {@code init} method is invoked by the {@code PreHashedMap} | |
| * constructor with an object array long enough for the map's rows. The method | |
| * must construct the hash chain for each row and store it in the appropriate | |
| * element of the array. | |
| * | |
| * <p> Each entry in the map is represented by a unique hash-chain node. The | |
| * final node of a hash chain is a two-element object array whose first element | |
| * is the entry's key and whose second element is the entry's value. A | |
| * non-final node of a hash chain is a three-element object array whose first | |
| * two elements are the entry's key and value and whose third element is the | |
| * next node in the chain. | |
| * | |
| * <p> Instances of this class are mutable and are not safe for concurrent | |
| * access. They may be made immutable and thread-safe via the appropriate | |
| * methods in the {@link java.util.Collections} utility class. | |
| * | |
| * <p> In the JDK build, subclasses of this class are typically created via the | |
| * {@code Hasher} program in the {@code make/tools/Hasher} directory. | |
| * | |
| * @author Mark Reinhold | |
| * @since 1.5 | |
| * | |
| * @see java.util.AbstractMap | |
| */ | |
| public abstract class PreHashedMap<V> | |
| extends AbstractMap<String,V> | |
| { | |
| private final int rows; | |
| private final int size; | |
| private final int shift; | |
| private final int mask; | |
| private final Object[] ht; | |
| /** | |
| * Creates a new map. | |
| * | |
| * <p> This constructor invokes the {@link #init init} method, passing it a | |
| * newly-constructed row array that is {@code rows} elements long. | |
| * | |
| * @param rows | |
| * The number of rows in the map | |
| * @param size | |
| * The number of entries in the map | |
| * @param shift | |
| * The value by which hash codes are right-shifted | |
| * @param mask | |
| * The value with which hash codes are masked after being shifted | |
| */ | |
| protected PreHashedMap(int rows, int size, int shift, int mask) { | |
| this.rows = rows; | |
| this.size = size; | |
| this.shift = shift; | |
| this.mask = mask; | |
| this.ht = new Object[rows]; | |
| init(ht); | |
| } | |
| /** | |
| * Initializes this map. | |
| * | |
| * <p> This method must construct the map's hash chains and store them into | |
| * the appropriate elements of the given hash-table row array. | |
| * | |
| * @param ht The row array to be initialized | |
| */ | |
| protected abstract void init(Object[] ht); | |
| @SuppressWarnings("unchecked") | |
| private V toV(Object x) { | |
| return (V)x; | |
| } | |
| public V get(Object k) { | |
| int h = (k.hashCode() >> shift) & mask; | |
| Object[] a = (Object[])ht[h]; | |
| if (a == null) return null; | |
| for (;;) { | |
| if (a[0].equals(k)) | |
| return toV(a[1]); | |
| if (a.length < 3) | |
| return null; | |
| a = (Object[])a[2]; | |
| } | |
| } | |
| /** | |
| * @throws UnsupportedOperationException | |
| * If the given key is not part of this map's initial key set | |
| */ | |
| public V put(String k, V v) { | |
| int h = (k.hashCode() >> shift) & mask; | |
| Object[] a = (Object[])ht[h]; | |
| if (a == null) | |
| throw new UnsupportedOperationException(k); | |
| for (;;) { | |
| if (a[0].equals(k)) { | |
| V ov = toV(a[1]); | |
| a[1] = v; | |
| return ov; | |
| } | |
| if (a.length < 3) | |
| throw new UnsupportedOperationException(k); | |
| a = (Object[])a[2]; | |
| } | |
| } | |
| public Set<String> keySet() { | |
| return new AbstractSet<> () { | |
| public int size() { | |
| return size; | |
| } | |
| public Iterator<String> iterator() { | |
| return new Iterator<>() { | |
| private int i = -1; | |
| Object[] a = null; | |
| String cur = null; | |
| private boolean findNext() { | |
| if (a != null) { | |
| if (a.length == 3) { | |
| a = (Object[])a[2]; | |
| cur = (String)a[0]; | |
| return true; | |
| } | |
| i++; | |
| a = null; | |
| } | |
| cur = null; | |
| if (i >= rows) | |
| return false; | |
| if (i < 0 || ht[i] == null) { | |
| do { | |
| if (++i >= rows) | |
| return false; | |
| } while (ht[i] == null); | |
| } | |
| a = (Object[])ht[i]; | |
| cur = (String)a[0]; | |
| return true; | |
| } | |
| public boolean hasNext() { | |
| if (cur != null) | |
| return true; | |
| return findNext(); | |
| } | |
| public String next() { | |
| if (cur == null) { | |
| if (!findNext()) | |
| throw new NoSuchElementException(); | |
| } | |
| String s = cur; | |
| cur = null; | |
| return s; | |
| } | |
| public void remove() { | |
| throw new UnsupportedOperationException(); | |
| } | |
| }; | |
| } | |
| }; | |
| } | |
| public Set<Map.Entry<String,V>> entrySet() { | |
| return new AbstractSet<Map.Entry<String,V>> () { | |
| public int size() { | |
| return size; | |
| } | |
| public Iterator<Map.Entry<String,V>> iterator() { | |
| return new Iterator<Map.Entry<String,V>>() { | |
| final Iterator<String> i = keySet().iterator(); | |
| public boolean hasNext() { | |
| return i.hasNext(); | |
| } | |
| public Map.Entry<String,V> next() { | |
| return new Map.Entry<String,V>() { | |
| final String k = i.next(); | |
| public String getKey() { return k; } | |
| public V getValue() { return get(k); } | |
| public int hashCode() { | |
| V v = get(k); | |
| return (k.hashCode() | |
| + (v == null | |
| ? 0 | |
| : v.hashCode())); | |
| } | |
| public boolean equals(Object ob) { | |
| if (ob == this) | |
| return true; | |
| if (!(ob instanceof Map.Entry)) | |
| return false; | |
| Map.Entry<?,?> that = (Map.Entry<?,?>)ob; | |
| return ((this.getKey() == null | |
| ? that.getKey() == null | |
| : this.getKey() | |
| .equals(that.getKey())) | |
| && | |
| (this.getValue() == null | |
| ? that.getValue() == null | |
| : this.getValue() | |
| .equals(that.getValue()))); | |
| } | |
| public V setValue(V v) { | |
| throw new UnsupportedOperationException(); | |
| } | |
| }; | |
| } | |
| public void remove() { | |
| throw new UnsupportedOperationException(); | |
| } | |
| }; | |
| } | |
| }; | |
| } | |
| } |