| /* |
| * Copyright (c) 2004, 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 <tt>init</tt> method is invoked by the <tt>PreHashedMap</tt> |
| * 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 |
| * <tt>Hasher</tt> program in the <tt>make/tools/Hasher</tt> 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 <tt>rows</tt> 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 rows |
| * 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<String> () { |
| |
| public int size() { |
| return size; |
| } |
| |
| public Iterator<String> iterator() { |
| return new Iterator<String>() { |
| 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>() { |
| 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())); |
| } |
| @SuppressWarnings("unchecked") |
| public boolean equals(Object ob) { |
| if (ob == this) |
| return true; |
| if (!(ob instanceof Map.Entry)) |
| return false; |
| Map.Entry<String,V> that |
| = (Map.Entry<String,V>)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(); |
| } |
| |
| }; |
| } |
| }; |
| } |
| |
| } |
