Showing the changes to java/pkg/java/util/BitSet.java (1 of 18352 files). Show all
Unified · Split
| @@ -0,0 +1,1191 @@ | |||
| 1 | /* | ||
| 2 | * Copyright (c) 1995, 2007, 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 java.util; | ||
| 27 | |||
| 28 | import java.io.*; | ||
| 29 | import java.nio.ByteBuffer; | ||
| 30 | import java.nio.ByteOrder; | ||
| 31 | import java.nio.LongBuffer; | ||
| 32 | |||
| 33 | /** | ||
| 34 | * This class implements a vector of bits that grows as needed. Each | ||
| 35 | * component of the bit set has a {@code boolean} value. The | ||
| 36 | * bits of a {@code BitSet} are indexed by nonnegative integers. | ||
| 37 | * Individual indexed bits can be examined, set, or cleared. One | ||
| 38 | * {@code BitSet} may be used to modify the contents of another | ||
| 39 | * {@code BitSet} through logical AND, logical inclusive OR, and | ||
| 40 | * logical exclusive OR operations. | ||
| 41 | * | ||
| 42 | * <p>By default, all bits in the set initially have the value | ||
| 43 | * {@code false}. | ||
| 44 | * | ||
| 45 | * <p>Every bit set has a current size, which is the number of bits | ||
| 46 | * of space currently in use by the bit set. Note that the size is | ||
| 47 | * related to the implementation of a bit set, so it may change with | ||
| 48 | * implementation. The length of a bit set relates to logical length | ||
| 49 | * of a bit set and is defined independently of implementation. | ||
| 50 | * | ||
| 51 | * <p>Unless otherwise noted, passing a null parameter to any of the | ||
| 52 | * methods in a {@code BitSet} will result in a | ||
| 53 | * {@code NullPointerException}. | ||
| 54 | * | ||
| 55 | * <p>A {@code BitSet} is not safe for multithreaded use without | ||
| 56 | * external synchronization. | ||
| 57 | * | ||
| 58 | * @author Arthur van Hoff | ||
| 59 | * @author Michael McCloskey | ||
| 60 | * @author Martin Buchholz | ||
| 61 | * @since JDK1.0 | ||
| 62 | */ | ||
| 63 | public class BitSet implements Cloneable, java.io.Serializable { | ||
| 64 | /* | ||
| 65 | * BitSets are packed into arrays of "words." Currently a word is | ||
| 66 | * a long, which consists of 64 bits, requiring 6 address bits. | ||
| 67 | * The choice of word size is determined purely by performance concerns. | ||
| 68 | */ | ||
| 69 | private final static int ADDRESS_BITS_PER_WORD = 6; | ||
| 70 | private final static int BITS_PER_WORD = 1 << ADDRESS_BITS_PER_WORD; | ||
| 71 | private final static int BIT_INDEX_MASK = BITS_PER_WORD - 1; | ||
| 72 | |||
| 73 | /* Used to shift left or right for a partial word mask */ | ||
| 74 | private static final long WORD_MASK = 0xffffffffffffffffL; | ||
| 75 | |||
| 76 | /** | ||
| 77 | * @serialField bits long[] | ||
| 78 | * | ||
| 79 | * The bits in this BitSet. The ith bit is stored in bits[i/64] at | ||
| 80 | * bit position i % 64 (where bit position 0 refers to the least | ||
| 81 | * significant bit and 63 refers to the most significant bit). | ||
| 82 | */ | ||
| 83 | private static final ObjectStreamField[] serialPersistentFields = { | ||
| 84 | new ObjectStreamField("bits", long[].class), | ||
| 85 | }; | ||
| 86 | |||
| 87 | /** | ||
| 88 | * The internal field corresponding to the serialField "bits". | ||
| 89 | */ | ||
| 90 | private long[] words; | ||
| 91 | |||
| 92 | /** | ||
| 93 | * The number of words in the logical size of this BitSet. | ||
| 94 | */ | ||
| 95 | private transient int wordsInUse = 0; | ||
| 96 | |||
| 97 | /** | ||
| 98 | * Whether the size of "words" is user-specified. If so, we assume | ||
| 99 | * the user knows what he's doing and try harder to preserve it. | ||
| 100 | */ | ||
| 101 | private transient boolean sizeIsSticky = false; | ||
| 102 | |||
| 103 | /* use serialVersionUID from JDK 1.0.2 for interoperability */ | ||
| 104 | private static final long serialVersionUID = 7997698588986878753L; | ||
| 105 | |||
| 106 | /** | ||
| 107 | * Given a bit index, return word index containing it. | ||
| 108 | */ | ||
| 109 | private static int wordIndex(int bitIndex) { | ||
| 110 | return bitIndex >> ADDRESS_BITS_PER_WORD; | ||
| 111 | } | ||
| 112 | |||
| 113 | /** | ||
| 114 | * Every public method must preserve these invariants. | ||
| 115 | */ | ||
| 116 | private void checkInvariants() { | ||
| 117 | assert(wordsInUse == 0 || words[wordsInUse - 1] != 0); | ||
| 118 | assert(wordsInUse >= 0 && wordsInUse <= words.length); | ||
| 119 | assert(wordsInUse == words.length || words[wordsInUse] == 0); | ||
| 120 | } | ||
| 121 | |||
| 122 | /** | ||
| 123 | * Sets the field wordsInUse to the logical size in words of the bit set. | ||
| 124 | * WARNING:This method assumes that the number of words actually in use is | ||
| 125 | * less than or equal to the current value of wordsInUse! | ||
| 126 | */ | ||
| 127 | private void recalculateWordsInUse() { | ||
| 128 | // Traverse the bitset until a used word is found | ||
| 129 | int i; | ||
| 130 | for (i = wordsInUse-1; i >= 0; i--) | ||
| 131 | if (words[i] != 0) | ||
| 132 | break; | ||
| 133 | |||
| 134 | wordsInUse = i+1; // The new logical size | ||
| 135 | } | ||
| 136 | |||
| 137 | /** | ||
| 138 | * Creates a new bit set. All bits are initially {@code false}. | ||
| 139 | */ | ||
| 140 | public BitSet() { | ||
| 141 | initWords(BITS_PER_WORD); | ||
| 142 | sizeIsSticky = false; | ||
| 143 | } | ||
| 144 | |||
| 145 | /** | ||
| 146 | * Creates a bit set whose initial size is large enough to explicitly | ||
| 147 | * represent bits with indices in the range {@code 0} through | ||
| 148 | * {@code nbits-1}. All bits are initially {@code false}. | ||
| 149 | * | ||
| 150 | * @param nbits the initial size of the bit set | ||
| 151 | * @throws NegativeArraySizeException if the specified initial size | ||
| 152 | * is negative | ||
| 153 | */ | ||
| 154 | public BitSet(int nbits) { | ||
| 155 | // nbits can't be negative; size 0 is OK | ||
| 156 | if (nbits < 0) | ||
| 157 | throw new NegativeArraySizeException("nbits < 0: " + nbits); | ||
| 158 | |||
| 159 | initWords(nbits); | ||
| 160 | sizeIsSticky = true; | ||
| 161 | } | ||
| 162 | |||
| 163 | private void initWords(int nbits) { | ||
| 164 | words = new long[wordIndex(nbits-1) + 1]; | ||
| 165 | } | ||
| 166 | |||
| 167 | /** | ||
| 168 | * Creates a bit set using words as the internal representation. | ||
| 169 | * The last word (if there is one) must be non-zero. | ||
| 170 | */ | ||
| 171 | private BitSet(long[] words) { | ||
| 172 | this.words = words; | ||
| 173 | this.wordsInUse = words.length; | ||
| 174 | checkInvariants(); | ||
| 175 | } | ||
| 176 | |||
| 177 | /** | ||
| 178 | * Returns a new bit set containing all the bits in the given long array. | ||
| 179 | * | ||
| 180 | * <p>More precisely, | ||
| 181 | * <br>{@code BitSet.valueOf(longs).get(n) == ((longs[n/64] & (1L<<(n%64))) != 0)} | ||
| 182 | * <br>for all {@code n < 64 * longs.length}. | ||
| 183 | * | ||
| 184 | * <p>This method is equivalent to | ||
| 185 | * {@code BitSet.valueOf(LongBuffer.wrap(longs))}. | ||
| 186 | * | ||
| 187 | * @param longs a long array containing a little-endian representation | ||
| 188 | * of a sequence of bits to be used as the initial bits of the | ||
| 189 | * new bit set | ||
| 190 | * @since 1.7 | ||
| 191 | */ | ||
| 192 | public static BitSet valueOf(long[] longs) { | ||
| 193 | int n; | ||
| 194 | for (n = longs.length; n > 0 && longs[n - 1] == 0; n--) | ||
| 195 | ; | ||
| 196 | return new BitSet(Arrays.copyOf(longs, n)); | ||
| 197 | } | ||
| 198 | |||
| 199 | /** | ||
| 200 | * Returns a new bit set containing all the bits in the given long | ||
| 201 | * buffer between its position and limit. | ||
| 202 | * | ||
| 203 | * <p>More precisely, | ||
| 204 | * <br>{@code BitSet.valueOf(lb).get(n) == ((lb.get(lb.position()+n/64) & (1L<<(n%64))) != 0)} | ||
| 205 | * <br>for all {@code n < 64 * lb.remaining()}. | ||
| 206 | * | ||
| 207 | * <p>The long buffer is not modified by this method, and no | ||
| 208 | * reference to the buffer is retained by the bit set. | ||
| 209 | * | ||
| 210 | * @param lb a long buffer containing a little-endian representation | ||
| 211 | * of a sequence of bits between its position and limit, to be | ||
| 212 | * used as the initial bits of the new bit set | ||
| 213 | * @since 1.7 | ||
| 214 | */ | ||
| 215 | public static BitSet valueOf(LongBuffer lb) { | ||
| 216 | lb = lb.slice(); | ||
| 217 | int n; | ||
| 218 | for (n = lb.remaining(); n > 0 && lb.get(n - 1) == 0; n--) | ||
| 219 | ; | ||
| 220 | long[] words = new long[n]; | ||
| 221 | lb.get(words); | ||
| 222 | return new BitSet(words); | ||
| 223 | } | ||
| 224 | |||
| 225 | /** | ||
| 226 | * Returns a new bit set containing all the bits in the given byte array. | ||
| 227 | * | ||
| 228 | * <p>More precisely, | ||
| 229 | * <br>{@code BitSet.valueOf(bytes).get(n) == ((bytes[n/8] & (1<<(n%8))) != 0)} | ||
| 230 | * <br>for all {@code n < 8 * bytes.length}. | ||
| 231 | * | ||
| 232 | * <p>This method is equivalent to | ||
| 233 | * {@code BitSet.valueOf(ByteBuffer.wrap(bytes))}. | ||
| 234 | * | ||
| 235 | * @param bytes a byte array containing a little-endian | ||
| 236 | * representation of a sequence of bits to be used as the | ||
| 237 | * initial bits of the new bit set | ||
| 238 | * @since 1.7 | ||
| 239 | */ | ||
| 240 | public static BitSet valueOf(byte[] bytes) { | ||
| 241 | return BitSet.valueOf(ByteBuffer.wrap(bytes)); | ||
| 242 | } | ||
| 243 | |||
| 244 | /** | ||
| 245 | * Returns a new bit set containing all the bits in the given byte | ||
| 246 | * buffer between its position and limit. | ||
| 247 | * | ||
| 248 | * <p>More precisely, | ||
| 249 | * <br>{@code BitSet.valueOf(bb).get(n) == ((bb.get(bb.position()+n/8) & (1<<(n%8))) != 0)} | ||
| 250 | * <br>for all {@code n < 8 * bb.remaining()}. | ||
| 251 | * | ||
| 252 | * <p>The byte buffer is not modified by this method, and no | ||
| 253 | * reference to the buffer is retained by the bit set. | ||
| 254 | * | ||
| 255 | * @param bb a byte buffer containing a little-endian representation | ||
| 256 | * of a sequence of bits between its position and limit, to be | ||
| 257 | * used as the initial bits of the new bit set | ||
| 258 | * @since 1.7 | ||
| 259 | */ | ||
| 260 | public static BitSet valueOf(ByteBuffer bb) { | ||
| 261 | bb = bb.slice().order(ByteOrder.LITTLE_ENDIAN); | ||
| 262 | int n; | ||
| 263 | for (n = bb.remaining(); n > 0 && bb.get(n - 1) == 0; n--) | ||
| 264 | ; | ||
| 265 | long[] words = new long[(n + 7) / 8]; | ||
| 266 | bb.limit(n); | ||
| 267 | int i = 0; | ||
| 268 | while (bb.remaining() >= 8) | ||
| 269 | words[i++] = bb.getLong(); | ||
| 270 | for (int remaining = bb.remaining(), j = 0; j < remaining; j++) | ||
| 271 | words[i] |= (bb.get() & 0xffL) << (8 * j); | ||
| 272 | return new BitSet(words); | ||
| 273 | } | ||
| 274 | |||
| 275 | /** | ||
| 276 | * Returns a new byte array containing all the bits in this bit set. | ||
| 277 | * | ||
| 278 | * <p>More precisely, if | ||
| 279 | * <br>{@code byte[] bytes = s.toByteArray();} | ||
| 280 | * <br>then {@code bytes.length == (s.length()+7)/8} and | ||
| 281 | * <br>{@code s.get(n) == ((bytes[n/8] & (1<<(n%8))) != 0)} | ||
| 282 | * <br>for all {@code n < 8 * bytes.length}. | ||
| 283 | * | ||
| 284 | * @return a byte array containing a little-endian representation | ||
| 285 | * of all the bits in this bit set | ||
| 286 | * @since 1.7 | ||
| 287 | */ | ||
| 288 | public byte[] toByteArray() { | ||
| 289 | int n = wordsInUse; | ||
| 290 | if (n == 0) | ||
| 291 | return new byte[0]; | ||
| 292 | int len = 8 * (n-1); | ||
| 293 | for (long x = words[n - 1]; x != 0; x >>>= 8) | ||
| 294 | len++; | ||
| 295 | byte[] bytes = new byte[len]; | ||
| 296 | ByteBuffer bb = ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN); | ||
| 297 | for (int i = 0; i < n - 1; i++) | ||
| 298 | bb.putLong(words[i]); | ||
| 299 | for (long x = words[n - 1]; x != 0; x >>>= 8) | ||
| 300 | bb.put((byte) (x & 0xff)); | ||
| 301 | return bytes; | ||
| 302 | } | ||
| 303 | |||
| 304 | /** | ||
| 305 | * Returns a new long array containing all the bits in this bit set. | ||
| 306 | * | ||
| 307 | * <p>More precisely, if | ||
| 308 | * <br>{@code long[] longs = s.toLongArray();} | ||
| 309 | * <br>then {@code longs.length == (s.length()+63)/64} and | ||
| 310 | * <br>{@code s.get(n) == ((longs[n/64] & (1L<<(n%64))) != 0)} | ||
| 311 | * <br>for all {@code n < 64 * longs.length}. | ||
| 312 | * | ||
| 313 | * @return a long array containing a little-endian representation | ||
| 314 | * of all the bits in this bit set | ||
| 315 | * @since 1.7 | ||
| 316 | */ | ||
| 317 | public long[] toLongArray() { | ||
| 318 | return Arrays.copyOf(words, wordsInUse); | ||
| 319 | } | ||
| 320 | |||
| 321 | /** | ||
| 322 | * Ensures that the BitSet can hold enough words. | ||
| 323 | * @param wordsRequired the minimum acceptable number of words. | ||
| 324 | */ | ||
| 325 | private void ensureCapacity(int wordsRequired) { | ||
| 326 | if (words.length < wordsRequired) { | ||
| 327 | // Allocate larger of doubled size or required size | ||
| 328 | int request = Math.max(2 * words.length, wordsRequired); | ||
| 329 | words = Arrays.copyOf(words, request); | ||
| 330 | sizeIsSticky = false; | ||
| 331 | } | ||
| 332 | } | ||
| 333 | |||
| 334 | /** | ||
| 335 | * Ensures that the BitSet can accommodate a given wordIndex, | ||
| 336 | * temporarily violating the invariants. The caller must | ||
| 337 | * restore the invariants before returning to the user, | ||
| 338 | * possibly using recalculateWordsInUse(). | ||
| 339 | * @param wordIndex the index to be accommodated. | ||
| 340 | */ | ||
| 341 | private void expandTo(int wordIndex) { | ||
| 342 | int wordsRequired = wordIndex+1; | ||
| 343 | if (wordsInUse < wordsRequired) { | ||
| 344 | ensureCapacity(wordsRequired); | ||
| 345 | wordsInUse = wordsRequired; | ||
| 346 | } | ||
| 347 | } | ||
| 348 | |||
| 349 | /** | ||
| 350 | * Checks that fromIndex ... toIndex is a valid range of bit indices. | ||
| 351 | */ | ||
| 352 | private static void checkRange(int fromIndex, int toIndex) { | ||
| 353 | if (fromIndex < 0) | ||
| 354 | throw new IndexOutOfBoundsException("fromIndex < 0: " + fromIndex); | ||
| 355 | if (toIndex < 0) | ||
| 356 | throw new IndexOutOfBoundsException("toIndex < 0: " + toIndex); | ||
| 357 | if (fromIndex > toIndex) | ||
| 358 | throw new IndexOutOfBoundsException("fromIndex: " + fromIndex + | ||
| 359 | " > toIndex: " + toIndex); | ||
| 360 | } | ||
| 361 | |||
| 362 | /** | ||
| 363 | * Sets the bit at the specified index to the complement of its | ||
| 364 | * current value. | ||
| 365 | * | ||
| 366 | * @param bitIndex the index of the bit to flip | ||
| 367 | * @throws IndexOutOfBoundsException if the specified index is negative | ||
| 368 | * @since 1.4 | ||
| 369 | */ | ||
| 370 | public void flip(int bitIndex) { | ||
| 371 | if (bitIndex < 0) | ||
| 372 | throw new IndexOutOfBoundsException("bitIndex < 0: " + bitIndex); | ||
| 373 | |||
| 374 | int wordIndex = wordIndex(bitIndex); | ||
| 375 | expandTo(wordIndex); | ||
| 376 | |||
| 377 | words[wordIndex] ^= (1L << bitIndex); | ||
| 378 | |||
| 379 | recalculateWordsInUse(); | ||
| 380 | checkInvariants(); | ||
| 381 | } | ||
| 382 | |||
| 383 | /** | ||
| 384 | * Sets each bit from the specified {@code fromIndex} (inclusive) to the | ||
| 385 | * specified {@code toIndex} (exclusive) to the complement of its current | ||
| 386 | * value. | ||
| 387 | * | ||
| 388 | * @param fromIndex index of the first bit to flip | ||
| 389 | * @param toIndex index after the last bit to flip | ||
| 390 | * @throws IndexOutOfBoundsException if {@code fromIndex} is negative, | ||
| 391 | * or {@code toIndex} is negative, or {@code fromIndex} is | ||
| 392 | * larger than {@code toIndex} | ||
| 393 | * @since 1.4 | ||
| 394 | */ | ||
| 395 | public void flip(int fromIndex, int toIndex) { | ||
| 396 | checkRange(fromIndex, toIndex); | ||
| 397 | |||
| 398 | if (fromIndex == toIndex) | ||
| 399 | return; | ||
| 400 | |||
| 401 | int startWordIndex = wordIndex(fromIndex); | ||
| 402 | int endWordIndex = wordIndex(toIndex - 1); | ||
| 403 | expandTo(endWordIndex); | ||
| 404 | |||
| 405 | long firstWordMask = WORD_MASK << fromIndex; | ||
| 406 | long lastWordMask = WORD_MASK >>> -toIndex; | ||
| 407 | if (startWordIndex == endWordIndex) { | ||
| 408 | // Case 1: One word | ||
| 409 | words[startWordIndex] ^= (firstWordMask & lastWordMask); | ||
| 410 | } else { | ||
| 411 | // Case 2: Multiple words | ||
| 412 | // Handle first word | ||
| 413 | words[startWordIndex] ^= firstWordMask; | ||
| 414 | |||
| 415 | // Handle intermediate words, if any | ||
| 416 | for (int i = startWordIndex+1; i < endWordIndex; i++) | ||
| 417 | words[i] ^= WORD_MASK; | ||
| 418 | |||
| 419 | // Handle last word | ||
| 420 | words[endWordIndex] ^= lastWordMask; | ||
| 421 | } | ||
| 422 | |||
| 423 | recalculateWordsInUse(); | ||
| 424 | checkInvariants(); | ||
| 425 | } | ||
| 426 | |||
| 427 | /** | ||
| 428 | * Sets the bit at the specified index to {@code true}. | ||
| 429 | * | ||
| 430 | * @param bitIndex a bit index | ||
| 431 | * @throws IndexOutOfBoundsException if the specified index is negative | ||
| 432 | * @since JDK1.0 | ||
| 433 | */ | ||
| 434 | public void set(int bitIndex) { | ||
| 435 | if (bitIndex < 0) | ||
| 436 | throw new IndexOutOfBoundsException("bitIndex < 0: " + bitIndex); | ||
| 437 | |||
| 438 | int wordIndex = wordIndex(bitIndex); | ||
| 439 | expandTo(wordIndex); | ||
| 440 | |||
| 441 | words[wordIndex] |= (1L << bitIndex); // Restores invariants | ||
| 442 | |||
| 443 | checkInvariants(); | ||
| 444 | } | ||
| 445 | |||
| 446 | /** | ||
| 447 | * Sets the bit at the specified index to the specified value. | ||
| 448 | * | ||
| 449 | * @param bitIndex a bit index | ||
| 450 | * @param value a boolean value to set | ||
| 451 | * @throws IndexOutOfBoundsException if the specified index is negative | ||
| 452 | * @since 1.4 | ||
| 453 | */ | ||
| 454 | public void set(int bitIndex, boolean value) { | ||
| 455 | if (value) | ||
| 456 | set(bitIndex); | ||
| 457 | else | ||
| 458 | clear(bitIndex); | ||
| 459 | } | ||
| 460 | |||
| 461 | /** | ||
| 462 | * Sets the bits from the specified {@code fromIndex} (inclusive) to the | ||
| 463 | * specified {@code toIndex} (exclusive) to {@code true}. | ||
| 464 | * | ||
| 465 | * @param fromIndex index of the first bit to be set | ||
| 466 | * @param toIndex index after the last bit to be set | ||
| 467 | * @throws IndexOutOfBoundsException if {@code fromIndex} is negative, | ||
| 468 | * or {@code toIndex} is negative, or {@code fromIndex} is | ||
| 469 | * larger than {@code toIndex} | ||
| 470 | * @since 1.4 | ||
| 471 | */ | ||
| 472 | public void set(int fromIndex, int toIndex) { | ||
| 473 | checkRange(fromIndex, toIndex); | ||
| 474 | |||
| 475 | if (fromIndex == toIndex) | ||
| 476 | return; | ||
| 477 | |||
| 478 | // Increase capacity if necessary | ||
| 479 | int startWordIndex = wordIndex(fromIndex); | ||
| 480 | int endWordIndex = wordIndex(toIndex - 1); | ||
| 481 | expandTo(endWordIndex); | ||
| 482 | |||
| 483 | long firstWordMask = WORD_MASK << fromIndex; | ||
| 484 | long lastWordMask = WORD_MASK >>> -toIndex; | ||
| 485 | if (startWordIndex == endWordIndex) { | ||
| 486 | // Case 1: One word | ||
| 487 | words[startWordIndex] |= (firstWordMask & lastWordMask); | ||
| 488 | } else { | ||
| 489 | // Case 2: Multiple words | ||
| 490 | // Handle first word | ||
| 491 | words[startWordIndex] |= firstWordMask; | ||
| 492 | |||
| 493 | // Handle intermediate words, if any | ||
| 494 | for (int i = startWordIndex+1; i < endWordIndex; i++) | ||
| 495 | words[i] = WORD_MASK; | ||
| 496 | |||
| 497 | // Handle last word (restores invariants) | ||
| 498 | words[endWordIndex] |= lastWordMask; | ||
| 499 | } | ||
| 500 | |||
| 501 | checkInvariants(); | ||
| 502 | } | ||
| 503 | |||
| 504 | /** | ||
| 505 | * Sets the bits from the specified {@code fromIndex} (inclusive) to the | ||
| 506 | * specified {@code toIndex} (exclusive) to the specified value. | ||
| 507 | * | ||
| 508 | * @param fromIndex index of the first bit to be set | ||
| 509 | * @param toIndex index after the last bit to be set | ||
| 510 | * @param value value to set the selected bits to | ||
| 511 | * @throws IndexOutOfBoundsException if {@code fromIndex} is negative, | ||
| 512 | * or {@code toIndex} is negative, or {@code fromIndex} is | ||
| 513 | * larger than {@code toIndex} | ||
| 514 | * @since 1.4 | ||
| 515 | */ | ||
| 516 | public void set(int fromIndex, int toIndex, boolean value) { | ||
| 517 | if (value) | ||
| 518 | set(fromIndex, toIndex); | ||
| 519 | else | ||
| 520 | clear(fromIndex, toIndex); | ||
| 521 | } | ||
| 522 | |||
| 523 | /** | ||
| 524 | * Sets the bit specified by the index to {@code false}. | ||
| 525 | * | ||
| 526 | * @param bitIndex the index of the bit to be cleared | ||
| 527 | * @throws IndexOutOfBoundsException if the specified index is negative | ||
| 528 | * @since JDK1.0 | ||
| 529 | */ | ||
| 530 | public void clear(int bitIndex) { | ||
| 531 | if (bitIndex < 0) | ||
| 532 | throw new IndexOutOfBoundsException("bitIndex < 0: " + bitIndex); | ||
| 533 | |||
| 534 | int wordIndex = wordIndex(bitIndex); | ||
| 535 | if (wordIndex >= wordsInUse) | ||
| 536 | return; | ||
| 537 | |||
| 538 | words[wordIndex] &= ~(1L << bitIndex); | ||
| 539 | |||
| 540 | recalculateWordsInUse(); | ||
| 541 | checkInvariants(); | ||
| 542 | } | ||
| 543 | |||
| 544 | /** | ||
| 545 | * Sets the bits from the specified {@code fromIndex} (inclusive) to the | ||
| 546 | * specified {@code toIndex} (exclusive) to {@code false}. | ||
| 547 | * | ||
| 548 | * @param fromIndex index of the first bit to be cleared | ||
| 549 | * @param toIndex index after the last bit to be cleared | ||
| 550 | * @throws IndexOutOfBoundsException if {@code fromIndex} is negative, | ||
| 551 | * or {@code toIndex} is negative, or {@code fromIndex} is | ||
| 552 | * larger than {@code toIndex} | ||
| 553 | * @since 1.4 | ||
| 554 | */ | ||
| 555 | public void clear(int fromIndex, int toIndex) { | ||
| 556 | checkRange(fromIndex, toIndex); | ||
| 557 | |||
| 558 | if (fromIndex == toIndex) | ||
| 559 | return; | ||
| 560 | |||
| 561 | int startWordIndex = wordIndex(fromIndex); | ||
| 562 | if (startWordIndex >= wordsInUse) | ||
| 563 | return; | ||
| 564 | |||
| 565 | int endWordIndex = wordIndex(toIndex - 1); | ||
| 566 | if (endWordIndex >= wordsInUse) { | ||
| 567 | toIndex = length(); | ||
| 568 | endWordIndex = wordsInUse - 1; | ||
| 569 | } | ||
| 570 | |||
| 571 | long firstWordMask = WORD_MASK << fromIndex; | ||
| 572 | long lastWordMask = WORD_MASK >>> -toIndex; | ||
| 573 | if (startWordIndex == endWordIndex) { | ||
| 574 | // Case 1: One word | ||
| 575 | words[startWordIndex] &= ~(firstWordMask & lastWordMask); | ||
| 576 | } else { | ||
| 577 | // Case 2: Multiple words | ||
| 578 | // Handle first word | ||
| 579 | words[startWordIndex] &= ~firstWordMask; | ||
| 580 | |||
| 581 | // Handle intermediate words, if any | ||
| 582 | for (int i = startWordIndex+1; i < endWordIndex; i++) | ||
| 583 | words[i] = 0; | ||
| 584 | |||
| 585 | // Handle last word | ||
| 586 | words[endWordIndex] &= ~lastWordMask; | ||
| 587 | } | ||
| 588 | |||
| 589 | recalculateWordsInUse(); | ||
| 590 | checkInvariants(); | ||
| 591 | } | ||
| 592 | |||
| 593 | /** | ||
| 594 | * Sets all of the bits in this BitSet to {@code false}. | ||
| 595 | * | ||
| 596 | * @since 1.4 | ||
| 597 | */ | ||
| 598 | public void clear() { | ||
| 599 | while (wordsInUse > 0) | ||
| 600 | words[--wordsInUse] = 0; | ||
| 601 | } | ||
| 602 | |||
| 603 | /** | ||
| 604 | * Returns the value of the bit with the specified index. The value | ||
| 605 | * is {@code true} if the bit with the index {@code bitIndex} | ||
| 606 | * is currently set in this {@code BitSet}; otherwise, the result | ||
| 607 | * is {@code false}. | ||
| 608 | * | ||
| 609 | * @param bitIndex the bit index | ||
| 610 | * @return the value of the bit with the specified index | ||
| 611 | * @throws IndexOutOfBoundsException if the specified index is negative | ||
| 612 | */ | ||
| 613 | public boolean get(int bitIndex) { | ||
| 614 | if (bitIndex < 0) | ||
| 615 | throw new IndexOutOfBoundsException("bitIndex < 0: " + bitIndex); | ||
| 616 | |||
| 617 | checkInvariants(); | ||
| 618 | |||
| 619 | int wordIndex = wordIndex(bitIndex); | ||
| 620 | return (wordIndex < wordsInUse) | ||
| 621 | && ((words[wordIndex] & (1L << bitIndex)) != 0); | ||
| 622 | } | ||
| 623 | |||
| 624 | /** | ||
| 625 | * Returns a new {@code BitSet} composed of bits from this {@code BitSet} | ||
| 626 | * from {@code fromIndex} (inclusive) to {@code toIndex} (exclusive). | ||
| 627 | * | ||
| 628 | * @param fromIndex index of the first bit to include | ||
| 629 | * @param toIndex index after the last bit to include | ||
| 630 | * @return a new {@code BitSet} from a range of this {@code BitSet} | ||
| 631 | * @throws IndexOutOfBoundsException if {@code fromIndex} is negative, | ||
| 632 | * or {@code toIndex} is negative, or {@code fromIndex} is | ||
| 633 | * larger than {@code toIndex} | ||
| 634 | * @since 1.4 | ||
| 635 | */ | ||
| 636 | public BitSet get(int fromIndex, int toIndex) { | ||
| 637 | checkRange(fromIndex, toIndex); | ||
| 638 | |||
| 639 | checkInvariants(); | ||
| 640 | |||
| 641 | int len = length(); | ||
| 642 | |||
| 643 | // If no set bits in range return empty bitset | ||
| 644 | if (len <= fromIndex || fromIndex == toIndex) | ||
| 645 | return new BitSet(0); | ||
| 646 | |||
| 647 | // An optimization | ||
| 648 | if (toIndex > len) | ||
| 649 | toIndex = len; | ||
| 650 | |||
| 651 | BitSet result = new BitSet(toIndex - fromIndex); | ||
| 652 | int targetWords = wordIndex(toIndex - fromIndex - 1) + 1; | ||
| 653 | int sourceIndex = wordIndex(fromIndex); | ||
| 654 | boolean wordAligned = ((fromIndex & BIT_INDEX_MASK) == 0); | ||
| 655 | |||
| 656 | // Process all words but the last word | ||
| 657 | for (int i = 0; i < targetWords - 1; i++, sourceIndex++) | ||
| 658 | result.words[i] = wordAligned ? words[sourceIndex] : | ||
| 659 | (words[sourceIndex] >>> fromIndex) | | ||
| 660 | (words[sourceIndex+1] << -fromIndex); | ||
| 661 | |||
| 662 | // Process the last word | ||
| 663 | long lastWordMask = WORD_MASK >>> -toIndex; | ||
| 664 | result.words[targetWords - 1] = | ||
| 665 | ((toIndex-1) & BIT_INDEX_MASK) < (fromIndex & BIT_INDEX_MASK) | ||
| 666 | ? /* straddles source words */ | ||
| 667 | ((words[sourceIndex] >>> fromIndex) | | ||
| 668 | (words[sourceIndex+1] & lastWordMask) << -fromIndex) | ||
| 669 | : | ||
| 670 | ((words[sourceIndex] & lastWordMask) >>> fromIndex); | ||
| 671 | |||
| 672 | // Set wordsInUse correctly | ||
| 673 | result.wordsInUse = targetWords; | ||
| 674 | result.recalculateWordsInUse(); | ||
| 675 | result.checkInvariants(); | ||
| 676 | |||
| 677 | return result; | ||
| 678 | } | ||
| 679 | |||
| 680 | /** | ||
| 681 | * Returns the index of the first bit that is set to {@code true} | ||
| 682 | * that occurs on or after the specified starting index. If no such | ||
| 683 | * bit exists then {@code -1} is returned. | ||
| 684 | * | ||
| 685 | * <p>To iterate over the {@code true} bits in a {@code BitSet}, | ||
| 686 | * use the following loop: | ||
| 687 | * | ||
| 688 | * <pre> {@code | ||
| 689 | * for (int i = bs.nextSetBit(0); i >= 0; i = bs.nextSetBit(i+1)) { | ||
| 690 | * // operate on index i here | ||
| 691 | * }}</pre> | ||
| 692 | * | ||
| 693 | * @param fromIndex the index to start checking from (inclusive) | ||
| 694 | * @return the index of the next set bit, or {@code -1} if there | ||
| 695 | * is no such bit | ||
| 696 | * @throws IndexOutOfBoundsException if the specified index is negative | ||
| 697 | * @since 1.4 | ||
| 698 | */ | ||
| 699 | public int nextSetBit(int fromIndex) { | ||
| 700 | if (fromIndex < 0) | ||
| 701 | throw new IndexOutOfBoundsException("fromIndex < 0: " + fromIndex); | ||
| 702 | |||
| 703 | checkInvariants(); | ||
| 704 | |||
| 705 | int u = wordIndex(fromIndex); | ||
| 706 | if (u >= wordsInUse) | ||
| 707 | return -1; | ||
| 708 | |||
| 709 | long word = words[u] & (WORD_MASK << fromIndex); | ||
| 710 | |||
| 711 | while (true) { | ||
| 712 | if (word != 0) | ||
| 713 | return (u * BITS_PER_WORD) + Long.numberOfTrailingZeros(word); | ||
| 714 | if (++u == wordsInUse) | ||
| 715 | return -1; | ||
| 716 | word = words[u]; | ||
| 717 | } | ||
| 718 | } | ||
| 719 | |||
| 720 | /** | ||
| 721 | * Returns the index of the first bit that is set to {@code false} | ||
| 722 | * that occurs on or after the specified starting index. | ||
| 723 | * | ||
| 724 | * @param fromIndex the index to start checking from (inclusive) | ||
| 725 | * @return the index of the next clear bit | ||
| 726 | * @throws IndexOutOfBoundsException if the specified index is negative | ||
| 727 | * @since 1.4 | ||
| 728 | */ | ||
| 729 | public int nextClearBit(int fromIndex) { | ||
| 730 | // Neither spec nor implementation handle bitsets of maximal length. | ||
| 731 | // See 4816253. | ||
| 732 | if (fromIndex < 0) | ||
| 733 | throw new IndexOutOfBoundsException("fromIndex < 0: " + fromIndex); | ||
| 734 | |||
| 735 | checkInvariants(); | ||
| 736 | |||
| 737 | int u = wordIndex(fromIndex); | ||
| 738 | if (u >= wordsInUse) | ||
| 739 | return fromIndex; | ||
| 740 | |||
| 741 | long word = ~words[u] & (WORD_MASK << fromIndex); | ||
| 742 | |||
| 743 | while (true) { | ||
| 744 | if (word != 0) | ||
| 745 | return (u * BITS_PER_WORD) + Long.numberOfTrailingZeros(word); | ||
| 746 | if (++u == wordsInUse) | ||
| 747 | return wordsInUse * BITS_PER_WORD; | ||
| 748 | word = ~words[u]; | ||
| 749 | } | ||
| 750 | } | ||
| 751 | |||
| 752 | /** | ||
| 753 | * Returns the index of the nearest bit that is set to {@code true} | ||
| 754 | * that occurs on or before the specified starting index. | ||
| 755 | * If no such bit exists, or if {@code -1} is given as the | ||
| 756 | * starting index, then {@code -1} is returned. | ||
| 757 | * | ||
| 758 | * <p>To iterate over the {@code true} bits in a {@code BitSet}, | ||
| 759 | * use the following loop: | ||
| 760 | * | ||
| 761 | * <pre> {@code | ||
| 762 | * for (int i = bs.length(); (i = bs.previousSetBit(i-1)) >= 0; ) { | ||
| 763 | * // operate on index i here | ||
| 764 | * }}</pre> | ||
| 765 | * | ||
| 766 | * @param fromIndex the index to start checking from (inclusive) | ||
| 767 | * @return the index of the previous set bit, or {@code -1} if there | ||
| 768 | * is no such bit | ||
| 769 | * @throws IndexOutOfBoundsException if the specified index is less | ||
| 770 | * than {@code -1} | ||
| 771 | * @since 1.7 | ||
| 772 | */ | ||
| 773 | public int previousSetBit(int fromIndex) { | ||
| 774 | if (fromIndex < 0) { | ||
| 775 | if (fromIndex == -1) | ||
| 776 | return -1; | ||
| 777 | throw new IndexOutOfBoundsException( | ||
| 778 | "fromIndex < -1: " + fromIndex); | ||
| 779 | } | ||
| 780 | |||
| 781 | checkInvariants(); | ||
| 782 | |||
| 783 | int u = wordIndex(fromIndex); | ||
| 784 | if (u >= wordsInUse) | ||
| 785 | return length() - 1; | ||
| 786 | |||
| 787 | long word = words[u] & (WORD_MASK >>> -(fromIndex+1)); | ||
| 788 | |||
| 789 | while (true) { | ||
| 790 | if (word != 0) | ||
| 791 | return (u+1) * BITS_PER_WORD - 1 - Long.numberOfLeadingZeros(word); | ||
| 792 | if (u-- == 0) | ||
| 793 | return -1; | ||
| 794 | word = words[u]; | ||
| 795 | } | ||
| 796 | } | ||
| 797 | |||
| 798 | /** | ||
| 799 | * Returns the index of the nearest bit that is set to {@code false} | ||
| 800 | * that occurs on or before the specified starting index. | ||
| 801 | * If no such bit exists, or if {@code -1} is given as the | ||
| 802 | * starting index, then {@code -1} is returned. | ||
| 803 | * | ||
| 804 | * @param fromIndex the index to start checking from (inclusive) | ||
| 805 | * @return the index of the previous clear bit, or {@code -1} if there | ||
| 806 | * is no such bit | ||
| 807 | * @throws IndexOutOfBoundsException if the specified index is less | ||
| 808 | * than {@code -1} | ||
| 809 | * @since 1.7 | ||
| 810 | */ | ||
| 811 | public int previousClearBit(int fromIndex) { | ||
| 812 | if (fromIndex < 0) { | ||
| 813 | if (fromIndex == -1) | ||
| 814 | return -1; | ||
| 815 | throw new IndexOutOfBoundsException( | ||
| 816 | "fromIndex < -1: " + fromIndex); | ||
| 817 | } | ||
| 818 | |||
| 819 | checkInvariants(); | ||
| 820 | |||
| 821 | int u = wordIndex(fromIndex); | ||
| 822 | if (u >= wordsInUse) | ||
| 823 | return fromIndex; | ||
| 824 | |||
| 825 | long word = ~words[u] & (WORD_MASK >>> -(fromIndex+1)); | ||
| 826 | |||
| 827 | while (true) { | ||
| 828 | if (word != 0) | ||
| 829 | return (u+1) * BITS_PER_WORD -1 - Long.numberOfLeadingZeros(word); | ||
| 830 | if (u-- == 0) | ||
| 831 | return -1; | ||
| 832 | word = ~words[u]; | ||
| 833 | } | ||
| 834 | } | ||
| 835 | |||
| 836 | /** | ||
| 837 | * Returns the "logical size" of this {@code BitSet}: the index of | ||
| 838 | * the highest set bit in the {@code BitSet} plus one. Returns zero | ||
| 839 | * if the {@code BitSet} contains no set bits. | ||
| 840 | * | ||
| 841 | * @return the logical size of this {@code BitSet} | ||
| 842 | * @since 1.2 | ||
| 843 | */ | ||
| 844 | public int length() { | ||
| 845 | if (wordsInUse == 0) | ||
| 846 | return 0; | ||
| 847 | |||
| 848 | return BITS_PER_WORD * (wordsInUse - 1) + | ||
| 849 | (BITS_PER_WORD - Long.numberOfLeadingZeros(words[wordsInUse - 1])); | ||
| 850 | } | ||
| 851 | |||
| 852 | /** | ||
| 853 | * Returns true if this {@code BitSet} contains no bits that are set | ||
| 854 | * to {@code true}. | ||
| 855 | * | ||
| 856 | * @return boolean indicating whether this {@code BitSet} is empty | ||
| 857 | * @since 1.4 | ||
| 858 | */ | ||
| 859 | public boolean isEmpty() { | ||
| 860 | return wordsInUse == 0; | ||
| 861 | } | ||
| 862 | |||
| 863 | /** | ||
| 864 | * Returns true if the specified {@code BitSet} has any bits set to | ||
| 865 | * {@code true} that are also set to {@code true} in this {@code BitSet}. | ||
| 866 | * | ||
| 867 | * @param set {@code BitSet} to intersect with | ||
| 868 | * @return boolean indicating whether this {@code BitSet} intersects | ||
| 869 | * the specified {@code BitSet} | ||
| 870 | * @since 1.4 | ||
| 871 | */ | ||
| 872 | public boolean intersects(BitSet set) { | ||
| 873 | for (int i = Math.min(wordsInUse, set.wordsInUse) - 1; i >= 0; i--) | ||
| 874 | if ((words[i] & set.words[i]) != 0) | ||
| 875 | return true; | ||
| 876 | return false; | ||
| 877 | } | ||
| 878 | |||
| 879 | /** | ||
| 880 | * Returns the number of bits set to {@code true} in this {@code BitSet}. | ||
| 881 | * | ||
| 882 | * @return the number of bits set to {@code true} in this {@code BitSet} | ||
| 883 | * @since 1.4 | ||
| 884 | */ | ||
| 885 | public int cardinality() { | ||
| 886 | int sum = 0; | ||
| 887 | for (int i = 0; i < wordsInUse; i++) | ||
| 888 | sum += Long.bitCount(words[i]); | ||
| 889 | return sum; | ||
| 890 | } | ||
| 891 | |||
| 892 | /** | ||
| 893 | * Performs a logical <b>AND</b> of this target bit set with the | ||
| 894 | * argument bit set. This bit set is modified so that each bit in it | ||
| 895 | * has the value {@code true} if and only if it both initially | ||
| 896 | * had the value {@code true} and the corresponding bit in the | ||
| 897 | * bit set argument also had the value {@code true}. | ||
| 898 | * | ||
| 899 | * @param set a bit set | ||
| 900 | */ | ||
| 901 | public void and(BitSet set) { | ||
| 902 | if (this == set) | ||
| 903 | return; | ||
| 904 | |||
| 905 | while (wordsInUse > set.wordsInUse) | ||
| 906 | words[--wordsInUse] = 0; | ||
| 907 | |||
| 908 | // Perform logical AND on words in common | ||
| 909 | for (int i = 0; i < wordsInUse; i++) | ||
| 910 | words[i] &= set.words[i]; | ||
| 911 | |||
| 912 | recalculateWordsInUse(); | ||
| 913 | checkInvariants(); | ||
| 914 | } | ||
| 915 | |||
| 916 | /** | ||
| 917 | * Performs a logical <b>OR</b> of this bit set with the bit set | ||
| 918 | * argument. This bit set is modified so that a bit in it has the | ||
| 919 | * value {@code true} if and only if it either already had the | ||
| 920 | * value {@code true} or the corresponding bit in the bit set | ||
| 921 | * argument has the value {@code true}. | ||
| 922 | * | ||
| 923 | * @param set a bit set | ||
| 924 | */ | ||
| 925 | public void or(BitSet set) { | ||
| 926 | if (this == set) | ||
| 927 | return; | ||
| 928 | |||
| 929 | int wordsInCommon = Math.min(wordsInUse, set.wordsInUse); | ||
| 930 | |||
| 931 | if (wordsInUse < set.wordsInUse) { | ||
| 932 | ensureCapacity(set.wordsInUse); | ||
| 933 | wordsInUse = set.wordsInUse; | ||
| 934 | } | ||
| 935 | |||
| 936 | // Perform logical OR on words in common | ||
| 937 | for (int i = 0; i < wordsInCommon; i++) | ||
| 938 | words[i] |= set.words[i]; | ||
| 939 | |||
| 940 | // Copy any remaining words | ||
| 941 | if (wordsInCommon < set.wordsInUse) | ||
| 942 | System.arraycopy(set.words, wordsInCommon, | ||
| 943 | words, wordsInCommon, | ||
| 944 | wordsInUse - wordsInCommon); | ||
| 945 | |||
| 946 | // recalculateWordsInUse() is unnecessary | ||
| 947 | checkInvariants(); | ||
| 948 | } | ||
| 949 | |||
| 950 | /** | ||
| 951 | * Performs a logical <b>XOR</b> of this bit set with the bit set | ||
| 952 | * argument. This bit set is modified so that a bit in it has the | ||
| 953 | * value {@code true} if and only if one of the following | ||
| 954 | * statements holds: | ||
| 955 | * <ul> | ||
| 956 | * <li>The bit initially has the value {@code true}, and the | ||
| 957 | * corresponding bit in the argument has the value {@code false}. | ||
| 958 | * <li>The bit initially has the value {@code false}, and the | ||
| 959 | * corresponding bit in the argument has the value {@code true}. | ||
| 960 | * </ul> | ||
| 961 | * | ||
| 962 | * @param set a bit set | ||
| 963 | */ | ||
| 964 | public void xor(BitSet set) { | ||
| 965 | int wordsInCommon = Math.min(wordsInUse, set.wordsInUse); | ||
| 966 | |||
| 967 | if (wordsInUse < set.wordsInUse) { | ||
| 968 | ensureCapacity(set.wordsInUse); | ||
| 969 | wordsInUse = set.wordsInUse; | ||
| 970 | } | ||
| 971 | |||
| 972 | // Perform logical XOR on words in common | ||
| 973 | for (int i = 0; i < wordsInCommon; i++) | ||
| 974 | words[i] ^= set.words[i]; | ||
| 975 | |||
| 976 | // Copy any remaining words | ||
| 977 | if (wordsInCommon < set.wordsInUse) | ||
| 978 | System.arraycopy(set.words, wordsInCommon, | ||
| 979 | words, wordsInCommon, | ||
| 980 | set.wordsInUse - wordsInCommon); | ||
| 981 | |||
| 982 | recalculateWordsInUse(); | ||
| 983 | checkInvariants(); | ||
| 984 | } | ||
| 985 | |||
| 986 | /** | ||
| 987 | * Clears all of the bits in this {@code BitSet} whose corresponding | ||
| 988 | * bit is set in the specified {@code BitSet}. | ||
| 989 | * | ||
| 990 | * @param set the {@code BitSet} with which to mask this | ||
| 991 | * {@code BitSet} | ||
| 992 | * @since 1.2 | ||
| 993 | */ | ||
| 994 | public void andNot(BitSet set) { | ||
| 995 | // Perform logical (a & !b) on words in common | ||
| 996 | for (int i = Math.min(wordsInUse, set.wordsInUse) - 1; i >= 0; i--) | ||
| 997 | words[i] &= ~set.words[i]; | ||
| 998 | |||
| 999 | recalculateWordsInUse(); | ||
| 1000 | checkInvariants(); | ||
| 1001 | } | ||
| 1002 | |||
| 1003 | /** | ||
| 1004 | * Returns the hash code value for this bit set. The hash code depends | ||
| 1005 | * only on which bits are set within this {@code BitSet}. | ||
| 1006 | * | ||
| 1007 | * <p>The hash code is defined to be the result of the following | ||
| 1008 | * calculation: | ||
| 1009 | * <pre> {@code | ||
| 1010 | * public int hashCode() { | ||
| 1011 | * long h = 1234; | ||
| 1012 | * long[] words = toLongArray(); | ||
| 1013 | * for (int i = words.length; --i >= 0; ) | ||
| 1014 | * h ^= words[i] * (i + 1); | ||
| 1015 | * return (int)((h >> 32) ^ h); | ||
| 1016 | * }}</pre> | ||
| 1017 | * Note that the hash code changes if the set of bits is altered. | ||
| 1018 | * | ||
| 1019 | * @return the hash code value for this bit set | ||
| 1020 | */ | ||
| 1021 | public int hashCode() { | ||
| 1022 | long h = 1234; | ||
| 1023 | for (int i = wordsInUse; --i >= 0; ) | ||
| 1024 | h ^= words[i] * (i + 1); | ||
| 1025 | |||
| 1026 | return (int)((h >> 32) ^ h); | ||
| 1027 | } | ||
| 1028 | |||
| 1029 | /** | ||
| 1030 | * Returns the number of bits of space actually in use by this | ||
| 1031 | * {@code BitSet} to represent bit values. | ||
| 1032 | * The maximum element in the set is the size - 1st element. | ||
| 1033 | * | ||
| 1034 | * @return the number of bits currently in this bit set | ||
| 1035 | */ | ||
| 1036 | public int size() { | ||
| 1037 | return words.length * BITS_PER_WORD; | ||
| 1038 | } | ||
| 1039 | |||
| 1040 | /** | ||
| 1041 | * Compares this object against the specified object. | ||
| 1042 | * The result is {@code true} if and only if the argument is | ||
| 1043 | * not {@code null} and is a {@code Bitset} object that has | ||
| 1044 | * exactly the same set of bits set to {@code true} as this bit | ||
| 1045 | * set. That is, for every nonnegative {@code int} index {@code k}, | ||
| 1046 | * <pre>((BitSet)obj).get(k) == this.get(k)</pre> | ||
| 1047 | * must be true. The current sizes of the two bit sets are not compared. | ||
| 1048 | * | ||
| 1049 | * @param obj the object to compare with | ||
| 1050 | * @return {@code true} if the objects are the same; | ||
| 1051 | * {@code false} otherwise | ||
| 1052 | * @see #size() | ||
| 1053 | */ | ||
| 1054 | public boolean equals(Object obj) { | ||
| 1055 | if (!(obj instanceof BitSet)) | ||
| 1056 | return false; | ||
| 1057 | if (this == obj) | ||
| 1058 | return true; | ||
| 1059 | |||
| 1060 | BitSet set = (BitSet) obj; | ||
| 1061 | |||
| 1062 | checkInvariants(); | ||
| 1063 | set.checkInvariants(); | ||
| 1064 | |||
| 1065 | if (wordsInUse != set.wordsInUse) | ||
| 1066 | return false; | ||
| 1067 | |||
| 1068 | // Check words in use by both BitSets | ||
| 1069 | for (int i = 0; i < wordsInUse; i++) | ||
| 1070 | if (words[i] != set.words[i]) | ||
| 1071 | return false; | ||
| 1072 | |||
| 1073 | return true; | ||
| 1074 | } | ||
| 1075 | |||
| 1076 | /** | ||
| 1077 | * Cloning this {@code BitSet} produces a new {@code BitSet} | ||
| 1078 | * that is equal to it. | ||
| 1079 | * The clone of the bit set is another bit set that has exactly the | ||
| 1080 | * same bits set to {@code true} as this bit set. | ||
| 1081 | * | ||
| 1082 | * @return a clone of this bit set | ||
| 1083 | * @see #size() | ||
| 1084 | */ | ||
| 1085 | public Object clone() { | ||
| 1086 | if (! sizeIsSticky) | ||
| 1087 | trimToSize(); | ||
| 1088 | |||
| 1089 | try { | ||
| 1090 | BitSet result = (BitSet) super.clone(); | ||
| 1091 | result.words = words.clone(); | ||
| 1092 | result.checkInvariants(); | ||
| 1093 | return result; | ||
| 1094 | } catch (CloneNotSupportedException e) { | ||
| 1095 | throw new InternalError(); | ||
| 1096 | } | ||
| 1097 | } | ||
| 1098 | |||
| 1099 | /** | ||
| 1100 | * Attempts to reduce internal storage used for the bits in this bit set. | ||
| 1101 | * Calling this method may, but is not required to, affect the value | ||
| 1102 | * returned by a subsequent call to the {@link #size()} method. | ||
| 1103 | */ | ||
| 1104 | private void trimToSize() { | ||
| 1105 | if (wordsInUse != words.length) { | ||
| 1106 | words = Arrays.copyOf(words, wordsInUse); | ||
| 1107 | checkInvariants(); | ||
| 1108 | } | ||
| 1109 | } | ||
| 1110 | |||
| 1111 | /** | ||
| 1112 | * Save the state of the {@code BitSet} instance to a stream (i.e., | ||
| 1113 | * serialize it). | ||
| 1114 | */ | ||
| 1115 | private void writeObject(ObjectOutputStream s) | ||
| 1116 | throws IOException { | ||
| 1117 | |||
| 1118 | checkInvariants(); | ||
| 1119 | |||
| 1120 | if (! sizeIsSticky) | ||
| 1121 | trimToSize(); | ||
| 1122 | |||
| 1123 | ObjectOutputStream.PutField fields = s.putFields(); | ||
| 1124 | fields.put("bits", words); | ||
| 1125 | s.writeFields(); | ||
| 1126 | } | ||
| 1127 | |||
| 1128 | /** | ||
| 1129 | * Reconstitute the {@code BitSet} instance from a stream (i.e., | ||
| 1130 | * deserialize it). | ||
| 1131 | */ | ||
| 1132 | private void readObject(ObjectInputStream s) | ||
| 1133 | throws IOException, ClassNotFoundException { | ||
| 1134 | |||
| 1135 | ObjectInputStream.GetField fields = s.readFields(); | ||
| 1136 | words = (long[]) fields.get("bits", null); | ||
| 1137 | |||
| 1138 | // Assume maximum length then find real length | ||
| 1139 | // because recalculateWordsInUse assumes maintenance | ||
| 1140 | // or reduction in logical size | ||
| 1141 | wordsInUse = words.length; | ||
| 1142 | recalculateWordsInUse(); | ||
| 1143 | sizeIsSticky = (words.length > 0 && words[words.length-1] == 0L); // heuristic | ||
| 1144 | checkInvariants(); | ||
| 1145 | } | ||
| 1146 | |||
| 1147 | /** | ||
| 1148 | * Returns a string representation of this bit set. For every index | ||
| 1149 | * for which this {@code BitSet} contains a bit in the set | ||
| 1150 | * state, the decimal representation of that index is included in | ||
| 1151 | * the result. Such indices are listed in order from lowest to | ||
| 1152 | * highest, separated by ", " (a comma and a space) and | ||
| 1153 | * surrounded by braces, resulting in the usual mathematical | ||
| 1154 | * notation for a set of integers. | ||
| 1155 | * | ||
| 1156 | * <p>Example: | ||
| 1157 | * <pre> | ||
| 1158 | * BitSet drPepper = new BitSet();</pre> | ||
| 1159 | * Now {@code drPepper.toString()} returns "{@code {}}".<p> | ||
| 1160 | * <pre> | ||
| 1161 | * drPepper.set(2);</pre> | ||
| 1162 | * Now {@code drPepper.toString()} returns "{@code {2}}".<p> | ||
| 1163 | * <pre> | ||
| 1164 | * drPepper.set(4); | ||
| 1165 | * drPepper.set(10);</pre> | ||
| 1166 | * Now {@code drPepper.toString()} returns "{@code {2, 4, 10}}". | ||
| 1167 | * | ||
| 1168 | * @return a string representation of this bit set | ||
| 1169 | */ | ||
| 1170 | public String toString() { | ||
| 1171 | checkInvariants(); | ||
| 1172 | |||
| 1173 | int numBits = (wordsInUse > 128) ? | ||
| 1174 | cardinality() : wordsInUse * BITS_PER_WORD; | ||
| 1175 | StringBuilder b = new StringBuilder(6*numBits + 2); | ||
| 1176 | b.append('{'); | ||
| 1177 | |||
| 1178 | int i = nextSetBit(0); | ||
| 1179 | if (i != -1) { | ||
| 1180 | b.append(i); | ||
| 1181 | for (i = nextSetBit(i+1); i >= 0; i = nextSetBit(i+1)) { | ||
| 1182 | int endOfRun = nextClearBit(i); | ||
| 1183 | do { b.append(", ").append(i); } | ||
| 1184 | while (++i < endOfRun); | ||
| 1185 | } | ||
| 1186 | } | ||
| 1187 | |||
| 1188 | b.append('}'); | ||
| 1189 | return b.toString(); | ||
| 1190 | } | ||
| 1191 | } | ||