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| 1 | +/* | |
| 2 | + * Copyright (c) 2004, 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. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 10 | + * | |
| 11 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 12 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 15 | + * accompanied this code). | |
| 16 | + * | |
| 17 | + * You should have received a copy of the GNU General Public License version | |
| 18 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 19 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 20 | + * | |
| 21 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * questions. | |
| 24 | + */ | |
| 25 | + | |
| 26 | +package sun.util; | |
| 27 | + | |
| 28 | +import java.util.Iterator; | |
| 29 | +import java.util.Map; | |
| 30 | +import java.util.Set; | |
| 31 | +import java.util.AbstractMap; | |
| 32 | +import java.util.AbstractSet; | |
| 33 | +import java.util.NoSuchElementException; | |
| 34 | + | |
| 35 | + | |
| 36 | +/** | |
| 37 | + * A precomputed hash map. | |
| 38 | + * | |
| 39 | + * <p> Subclasses of this class are of the following form: | |
| 40 | + * | |
| 41 | + * <blockquote><pre> | |
| 42 | + * class FooMap | |
| 43 | + * extends sun.util.PreHashedMap<String> | |
| 44 | + * { | |
| 45 | + * | |
| 46 | + * private FooMap() { | |
| 47 | + * super(ROWS, SIZE, SHIFT, MASK); | |
| 48 | + * } | |
| 49 | + * | |
| 50 | + * protected void init(Object[] ht) { | |
| 51 | + * ht[0] = new Object[] { "key-1", value_1 }; | |
| 52 | + * ht[1] = new Object[] { "key-2", value_2, | |
| 53 | + * new Object { "key-3", value_3 } }; | |
| 54 | + * ... | |
| 55 | + * } | |
| 56 | + * | |
| 57 | + * }</pre></blockquote> | |
| 58 | + * | |
| 59 | + * <p> The <tt>init</tt> method is invoked by the <tt>PreHashedMap</tt> | |
| 60 | + * constructor with an object array long enough for the map's rows. The method | |
| 61 | + * must construct the hash chain for each row and store it in the appropriate | |
| 62 | + * element of the array. | |
| 63 | + * | |
| 64 | + * <p> Each entry in the map is represented by a unique hash-chain node. The | |
| 65 | + * final node of a hash chain is a two-element object array whose first element | |
| 66 | + * is the entry's key and whose second element is the entry's value. A | |
| 67 | + * non-final node of a hash chain is a three-element object array whose first | |
| 68 | + * two elements are the entry's key and value and whose third element is the | |
| 69 | + * next node in the chain. | |
| 70 | + * | |
| 71 | + * <p> Instances of this class are mutable and are not safe for concurrent | |
| 72 | + * access. They may be made immutable and thread-safe via the appropriate | |
| 73 | + * methods in the {@link java.util.Collections} utility class. | |
| 74 | + * | |
| 75 | + * <p> In the JDK build, subclasses of this class are typically created via the | |
| 76 | + * <tt>Hasher</tt> program in the <tt>make/tools/Hasher</tt> directory. | |
| 77 | + * | |
| 78 | + * @author Mark Reinhold | |
| 79 | + * @since 1.5 | |
| 80 | + * | |
| 81 | + * @see java.util.AbstractMap | |
| 82 | + */ | |
| 83 | + | |
| 84 | +public abstract class PreHashedMap<V> | |
| 85 | + extends AbstractMap<String,V> | |
| 86 | +{ | |
| 87 | + | |
| 88 | + private final int rows; | |
| 89 | + private final int size; | |
| 90 | + private final int shift; | |
| 91 | + private final int mask; | |
| 92 | + private final Object[] ht; | |
| 93 | + | |
| 94 | + /** | |
| 95 | + * Creates a new map. | |
| 96 | + * | |
| 97 | + * <p> This constructor invokes the {@link #init init} method, passing it a | |
| 98 | + * newly-constructed row array that is <tt>rows</tt> elements long. | |
| 99 | + * | |
| 100 | + * @param rows | |
| 101 | + * The number of rows in the map | |
| 102 | + * @param size | |
| 103 | + * The number of entries in the map | |
| 104 | + * @param shift | |
| 105 | + * The value by which hash codes are right-shifted | |
| 106 | + * @param mask | |
| 107 | + * The value with which hash codes are masked after being shifted | |
| 108 | + */ | |
| 109 | + protected PreHashedMap(int rows, int size, int shift, int mask) { | |
| 110 | + this.rows = rows; | |
| 111 | + this.size = size; | |
| 112 | + this.shift = shift; | |
| 113 | + this.mask = mask; | |
| 114 | + this.ht = new Object[rows]; | |
| 115 | + init(ht); | |
| 116 | + } | |
| 117 | + | |
| 118 | + /** | |
| 119 | + * Initializes this map. | |
| 120 | + * | |
| 121 | + * <p> This method must construct the map's hash chains and store them into | |
| 122 | + * the appropriate elements of the given hash-table row array. | |
| 123 | + * | |
| 124 | + * @param rows | |
| 125 | + * The row array to be initialized | |
| 126 | + */ | |
| 127 | + protected abstract void init(Object[] ht); | |
| 128 | + | |
| 129 | + // @SuppressWarnings("unchecked") | |
| 130 | + private V toV(Object x) { | |
| 131 | + return (V)x; | |
| 132 | + } | |
| 133 | + | |
| 134 | + public V get(Object k) { | |
| 135 | + int h = (k.hashCode() >> shift) & mask; | |
| 136 | + Object[] a = (Object[])ht[h]; | |
| 137 | + if (a == null) return null; | |
| 138 | + for (;;) { | |
| 139 | + if (a[0].equals(k)) | |
| 140 | + return toV(a[1]); | |
| 141 | + if (a.length < 3) | |
| 142 | + return null; | |
| 143 | + a = (Object[])a[2]; | |
| 144 | + } | |
| 145 | + } | |
| 146 | + | |
| 147 | + /** | |
| 148 | + * @throws UnsupportedOperationException | |
| 149 | + * If the given key is not part of this map's initial key set | |
| 150 | + */ | |
| 151 | + public V put(String k, V v) { | |
| 152 | + int h = (k.hashCode() >> shift) & mask; | |
| 153 | + Object[] a = (Object[])ht[h]; | |
| 154 | + if (a == null) | |
| 155 | + throw new UnsupportedOperationException(k); | |
| 156 | + for (;;) { | |
| 157 | + if (a[0].equals(k)) { | |
| 158 | + V ov = toV(a[1]); | |
| 159 | + a[1] = v; | |
| 160 | + return ov; | |
| 161 | + } | |
| 162 | + if (a.length < 3) | |
| 163 | + throw new UnsupportedOperationException(k); | |
| 164 | + a = (Object[])a[2]; | |
| 165 | + } | |
| 166 | + } | |
| 167 | + | |
| 168 | + public Set<String> keySet() { | |
| 169 | + return new AbstractSet<String> () { | |
| 170 | + | |
| 171 | + public int size() { | |
| 172 | + return size; | |
| 173 | + } | |
| 174 | + | |
| 175 | + public Iterator<String> iterator() { | |
| 176 | + return new Iterator<String>() { | |
| 177 | + private int i = -1; | |
| 178 | + Object[] a = null; | |
| 179 | + String cur = null; | |
| 180 | + | |
| 181 | + private boolean findNext() { | |
| 182 | + if (a != null) { | |
| 183 | + if (a.length == 3) { | |
| 184 | + a = (Object[])a[2]; | |
| 185 | + cur = (String)a[0]; | |
| 186 | + return true; | |
| 187 | + } | |
| 188 | + i++; | |
| 189 | + a = null; | |
| 190 | + } | |
| 191 | + cur = null; | |
| 192 | + if (i >= rows) | |
| 193 | + return false; | |
| 194 | + if (i < 0 || ht[i] == null) { | |
| 195 | + do { | |
| 196 | + if (++i >= rows) | |
| 197 | + return false; | |
| 198 | + } while (ht[i] == null); | |
| 199 | + } | |
| 200 | + a = (Object[])ht[i]; | |
| 201 | + cur = (String)a[0]; | |
| 202 | + return true; | |
| 203 | + } | |
| 204 | + | |
| 205 | + public boolean hasNext() { | |
| 206 | + if (cur != null) | |
| 207 | + return true; | |
| 208 | + return findNext(); | |
| 209 | + } | |
| 210 | + | |
| 211 | + public String next() { | |
| 212 | + if (cur == null) { | |
| 213 | + if (!findNext()) | |
| 214 | + throw new NoSuchElementException(); | |
| 215 | + } | |
| 216 | + String s = cur; | |
| 217 | + cur = null; | |
| 218 | + return s; | |
| 219 | + } | |
| 220 | + | |
| 221 | + public void remove() { | |
| 222 | + throw new UnsupportedOperationException(); | |
| 223 | + } | |
| 224 | + | |
| 225 | + }; | |
| 226 | + } | |
| 227 | + }; | |
| 228 | + } | |
| 229 | + | |
| 230 | + public Set<Map.Entry<String,V>> entrySet() { | |
| 231 | + return new AbstractSet<Map.Entry<String,V>> () { | |
| 232 | + | |
| 233 | + public int size() { | |
| 234 | + return size; | |
| 235 | + } | |
| 236 | + | |
| 237 | + public Iterator<Map.Entry<String,V>> iterator() { | |
| 238 | + return new Iterator<Map.Entry<String,V>>() { | |
| 239 | + final Iterator<String> i = keySet().iterator(); | |
| 240 | + | |
| 241 | + public boolean hasNext() { | |
| 242 | + return i.hasNext(); | |
| 243 | + } | |
| 244 | + | |
| 245 | + public Map.Entry<String,V> next() { | |
| 246 | + return new Map.Entry<String,V>() { | |
| 247 | + String k = i.next(); | |
| 248 | + public String getKey() { return k; } | |
| 249 | + public V getValue() { return get(k); } | |
| 250 | + public int hashCode() { | |
| 251 | + V v = get(k); | |
| 252 | + return (k.hashCode() | |
| 253 | + + (v == null | |
| 254 | + ? 0 | |
| 255 | + : v.hashCode())); | |
| 256 | + } | |
| 257 | + public boolean equals(Object ob) { | |
| 258 | + if (ob == this) | |
| 259 | + return true; | |
| 260 | + if (!(ob instanceof Map.Entry)) | |
| 261 | + return false; | |
| 262 | + Map.Entry<String,V> that | |
| 263 | + = (Map.Entry<String,V>)ob; | |
| 264 | + return ((this.getKey() == null | |
| 265 | + ? that.getKey() == null | |
| 266 | + : this.getKey() | |
| 267 | + .equals(that.getKey())) | |
| 268 | + && | |
| 269 | + (this.getValue() == null | |
| 270 | + ? that.getValue() == null | |
| 271 | + : this.getValue() | |
| 272 | + .equals(that.getValue()))); | |
| 273 | + } | |
| 274 | + public V setValue(V v) { | |
| 275 | + throw new UnsupportedOperationException(); | |
| 276 | + } | |
| 277 | + }; | |
| 278 | + } | |
| 279 | + | |
| 280 | + public void remove() { | |
| 281 | + throw new UnsupportedOperationException(); | |
| 282 | + } | |
| 283 | + | |
| 284 | + }; | |
| 285 | + } | |
| 286 | + }; | |
| 287 | + } | |
| 288 | + | |
| 289 | +} | |