001/* 002 * Copyright (C) 2008 The Guava Authors 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except 005 * in compliance with the License. You may obtain a copy of the License at 006 * 007 * http://www.apache.org/licenses/LICENSE-2.0 008 * 009 * Unless required by applicable law or agreed to in writing, software distributed under the License 010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express 011 * or implied. See the License for the specific language governing permissions and limitations under 012 * the License. 013 */ 014 015package com.google.common.primitives; 016 017import static com.google.common.base.Preconditions.checkArgument; 018import static com.google.common.base.Preconditions.checkElementIndex; 019import static com.google.common.base.Preconditions.checkNotNull; 020import static com.google.common.base.Preconditions.checkPositionIndexes; 021 022import com.google.common.annotations.Beta; 023import com.google.common.annotations.GwtCompatible; 024import com.google.common.annotations.GwtIncompatible; 025import com.google.common.base.Converter; 026import java.io.Serializable; 027import java.util.AbstractList; 028import java.util.Arrays; 029import java.util.Collection; 030import java.util.Collections; 031import java.util.Comparator; 032import java.util.List; 033import java.util.RandomAccess; 034 035/** 036 * Static utility methods pertaining to {@code short} primitives, that are not already found in 037 * either {@link Short} or {@link Arrays}. 038 * 039 * <p>See the Guava User Guide article on 040 * <a href="https://github.com/google/guava/wiki/PrimitivesExplained">primitive utilities</a>. 041 * 042 * @author Kevin Bourrillion 043 * @since 1.0 044 */ 045@GwtCompatible(emulated = true) 046public final class Shorts { 047 private Shorts() {} 048 049 /** 050 * The number of bytes required to represent a primitive {@code short} value. 051 * 052 * <p><b>Java 8 users:</b> use {@link Short#BYTES} instead. 053 */ 054 public static final int BYTES = Short.SIZE / Byte.SIZE; 055 056 /** 057 * The largest power of two that can be represented as a {@code short}. 058 * 059 * @since 10.0 060 */ 061 public static final short MAX_POWER_OF_TWO = 1 << (Short.SIZE - 2); 062 063 /** 064 * Returns a hash code for {@code value}; equal to the result of invoking 065 * {@code ((Short) value).hashCode()}. 066 * 067 * <p><b>Java 8 users:</b> use {@link Short#hashCode(short)} instead. 068 * 069 * @param value a primitive {@code short} value 070 * @return a hash code for the value 071 */ 072 public static int hashCode(short value) { 073 return value; 074 } 075 076 /** 077 * Returns the {@code short} value that is equal to {@code value}, if possible. 078 * 079 * @param value any value in the range of the {@code short} type 080 * @return the {@code short} value that equals {@code value} 081 * @throws IllegalArgumentException if {@code value} is greater than {@link Short#MAX_VALUE} or 082 * less than {@link Short#MIN_VALUE} 083 */ 084 public static short checkedCast(long value) { 085 short result = (short) value; 086 checkArgument(result == value, "Out of range: %s", value); 087 return result; 088 } 089 090 /** 091 * Returns the {@code short} nearest in value to {@code value}. 092 * 093 * @param value any {@code long} value 094 * @return the same value cast to {@code short} if it is in the range of the {@code short} type, 095 * {@link Short#MAX_VALUE} if it is too large, or {@link Short#MIN_VALUE} if it is too small 096 */ 097 public static short saturatedCast(long value) { 098 if (value > Short.MAX_VALUE) { 099 return Short.MAX_VALUE; 100 } 101 if (value < Short.MIN_VALUE) { 102 return Short.MIN_VALUE; 103 } 104 return (short) value; 105 } 106 107 /** 108 * Compares the two specified {@code short} values. The sign of the value returned is the same as 109 * that of {@code ((Short) a).compareTo(b)}. 110 * 111 * <p><b>Note for Java 7 and later:</b> this method should be treated as deprecated; use the 112 * equivalent {@link Short#compare} method instead. 113 * 114 * @param a the first {@code short} to compare 115 * @param b the second {@code short} to compare 116 * @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is 117 * greater than {@code b}; or zero if they are equal 118 */ 119 public static int compare(short a, short b) { 120 return a - b; // safe due to restricted range 121 } 122 123 /** 124 * Returns {@code true} if {@code target} is present as an element anywhere in {@code array}. 125 * 126 * @param array an array of {@code short} values, possibly empty 127 * @param target a primitive {@code short} value 128 * @return {@code true} if {@code array[i] == target} for some value of {@code 129 * i} 130 */ 131 public static boolean contains(short[] array, short target) { 132 for (short value : array) { 133 if (value == target) { 134 return true; 135 } 136 } 137 return false; 138 } 139 140 /** 141 * Returns the index of the first appearance of the value {@code target} in {@code array}. 142 * 143 * @param array an array of {@code short} values, possibly empty 144 * @param target a primitive {@code short} value 145 * @return the least index {@code i} for which {@code array[i] == target}, or {@code -1} if no 146 * such index exists. 147 */ 148 public static int indexOf(short[] array, short target) { 149 return indexOf(array, target, 0, array.length); 150 } 151 152 // TODO(kevinb): consider making this public 153 private static int indexOf(short[] array, short target, int start, int end) { 154 for (int i = start; i < end; i++) { 155 if (array[i] == target) { 156 return i; 157 } 158 } 159 return -1; 160 } 161 162 /** 163 * Returns the start position of the first occurrence of the specified {@code 164 * target} within {@code array}, or {@code -1} if there is no such occurrence. 165 * 166 * <p>More formally, returns the lowest index {@code i} such that 167 * {@code Arrays.copyOfRange(array, i, i + target.length)} contains exactly the same elements as 168 * {@code target}. 169 * 170 * @param array the array to search for the sequence {@code target} 171 * @param target the array to search for as a sub-sequence of {@code array} 172 */ 173 public static int indexOf(short[] array, short[] target) { 174 checkNotNull(array, "array"); 175 checkNotNull(target, "target"); 176 if (target.length == 0) { 177 return 0; 178 } 179 180 outer: 181 for (int i = 0; i < array.length - target.length + 1; i++) { 182 for (int j = 0; j < target.length; j++) { 183 if (array[i + j] != target[j]) { 184 continue outer; 185 } 186 } 187 return i; 188 } 189 return -1; 190 } 191 192 /** 193 * Returns the index of the last appearance of the value {@code target} in {@code array}. 194 * 195 * @param array an array of {@code short} values, possibly empty 196 * @param target a primitive {@code short} value 197 * @return the greatest index {@code i} for which {@code array[i] == target}, or {@code -1} if no 198 * such index exists. 199 */ 200 public static int lastIndexOf(short[] array, short target) { 201 return lastIndexOf(array, target, 0, array.length); 202 } 203 204 // TODO(kevinb): consider making this public 205 private static int lastIndexOf(short[] array, short target, int start, int end) { 206 for (int i = end - 1; i >= start; i--) { 207 if (array[i] == target) { 208 return i; 209 } 210 } 211 return -1; 212 } 213 214 /** 215 * Returns the least value present in {@code array}. 216 * 217 * @param array a <i>nonempty</i> array of {@code short} values 218 * @return the value present in {@code array} that is less than or equal to every other value in 219 * the array 220 * @throws IllegalArgumentException if {@code array} is empty 221 */ 222 public static short min(short... array) { 223 checkArgument(array.length > 0); 224 short min = array[0]; 225 for (int i = 1; i < array.length; i++) { 226 if (array[i] < min) { 227 min = array[i]; 228 } 229 } 230 return min; 231 } 232 233 /** 234 * Returns the greatest value present in {@code array}. 235 * 236 * @param array a <i>nonempty</i> array of {@code short} values 237 * @return the value present in {@code array} that is greater than or equal to every other value 238 * in the array 239 * @throws IllegalArgumentException if {@code array} is empty 240 */ 241 public static short max(short... array) { 242 checkArgument(array.length > 0); 243 short max = array[0]; 244 for (int i = 1; i < array.length; i++) { 245 if (array[i] > max) { 246 max = array[i]; 247 } 248 } 249 return max; 250 } 251 252 /** 253 * Returns the value nearest to {@code value} which is within the closed range {@code [min..max]}. 254 * 255 * <p>If {@code value} is within the range {@code [min..max]}, {@code value} is returned 256 * unchanged. If {@code value} is less than {@code min}, {@code min} is returned, and if 257 * {@code value} is greater than {@code max}, {@code max} is returned. 258 * 259 * @param value the {@code short} value to constrain 260 * @param min the lower bound (inclusive) of the range to constrain {@code value} to 261 * @param max the upper bound (inclusive) of the range to constrain {@code value} to 262 * @throws IllegalArgumentException if {@code min > max} 263 * @since 21.0 264 */ 265 @Beta 266 public static short constrainToRange(short value, short min, short max) { 267 checkArgument(min <= max, "min (%s) must be less than or equal to max (%s)", min, max); 268 return value < min ? min : value < max ? value : max; 269 } 270 271 /** 272 * Returns the values from each provided array combined into a single array. For example, 273 * {@code concat(new short[] {a, b}, new short[] {}, new short[] {c}} returns the array 274 * {@code {a, b, c}}. 275 * 276 * @param arrays zero or more {@code short} arrays 277 * @return a single array containing all the values from the source arrays, in order 278 */ 279 public static short[] concat(short[]... arrays) { 280 int length = 0; 281 for (short[] array : arrays) { 282 length += array.length; 283 } 284 short[] result = new short[length]; 285 int pos = 0; 286 for (short[] array : arrays) { 287 System.arraycopy(array, 0, result, pos, array.length); 288 pos += array.length; 289 } 290 return result; 291 } 292 293 /** 294 * Returns a big-endian representation of {@code value} in a 2-element byte array; equivalent to 295 * {@code ByteBuffer.allocate(2).putShort(value).array()}. For example, the input value {@code 296 * (short) 0x1234} would yield the byte array {@code {0x12, 0x34}}. 297 * 298 * <p>If you need to convert and concatenate several values (possibly even of different types), 299 * use a shared {@link java.nio.ByteBuffer} instance, or use 300 * {@link com.google.common.io.ByteStreams#newDataOutput()} to get a growable buffer. 301 */ 302 @GwtIncompatible // doesn't work 303 public static byte[] toByteArray(short value) { 304 return new byte[] {(byte) (value >> 8), (byte) value}; 305 } 306 307 /** 308 * Returns the {@code short} value whose big-endian representation is stored in the first 2 bytes 309 * of {@code bytes}; equivalent to {@code ByteBuffer.wrap(bytes).getShort()}. For example, the 310 * input byte array {@code {0x54, 0x32}} would yield the {@code short} value {@code 0x5432}. 311 * 312 * <p>Arguably, it's preferable to use {@link java.nio.ByteBuffer}; that library exposes much more 313 * flexibility at little cost in readability. 314 * 315 * @throws IllegalArgumentException if {@code bytes} has fewer than 2 elements 316 */ 317 @GwtIncompatible // doesn't work 318 public static short fromByteArray(byte[] bytes) { 319 checkArgument(bytes.length >= BYTES, "array too small: %s < %s", bytes.length, BYTES); 320 return fromBytes(bytes[0], bytes[1]); 321 } 322 323 /** 324 * Returns the {@code short} value whose byte representation is the given 2 bytes, in big-endian 325 * order; equivalent to {@code Shorts.fromByteArray(new byte[] {b1, b2})}. 326 * 327 * @since 7.0 328 */ 329 @GwtIncompatible // doesn't work 330 public static short fromBytes(byte b1, byte b2) { 331 return (short) ((b1 << 8) | (b2 & 0xFF)); 332 } 333 334 private static final class ShortConverter extends Converter<String, Short> 335 implements Serializable { 336 static final ShortConverter INSTANCE = new ShortConverter(); 337 338 @Override 339 protected Short doForward(String value) { 340 return Short.decode(value); 341 } 342 343 @Override 344 protected String doBackward(Short value) { 345 return value.toString(); 346 } 347 348 @Override 349 public String toString() { 350 return "Shorts.stringConverter()"; 351 } 352 353 private Object readResolve() { 354 return INSTANCE; 355 } 356 357 private static final long serialVersionUID = 1; 358 } 359 360 /** 361 * Returns a serializable converter object that converts between strings and shorts using 362 * {@link Short#decode} and {@link Short#toString()}. The returned converter throws 363 * {@link NumberFormatException} if the input string is invalid. 364 * 365 * <p><b>Warning:</b> please see {@link Short#decode} to understand exactly how strings are 366 * parsed. For example, the string {@code "0123"} is treated as <i>octal</i> and converted to the 367 * value {@code 83}. 368 * 369 * @since 16.0 370 */ 371 @Beta 372 public static Converter<String, Short> stringConverter() { 373 return ShortConverter.INSTANCE; 374 } 375 376 /** 377 * Returns an array containing the same values as {@code array}, but guaranteed to be of a 378 * specified minimum length. If {@code array} already has a length of at least {@code minLength}, 379 * it is returned directly. Otherwise, a new array of size {@code minLength + padding} is 380 * returned, containing the values of {@code array}, and zeroes in the remaining places. 381 * 382 * @param array the source array 383 * @param minLength the minimum length the returned array must guarantee 384 * @param padding an extra amount to "grow" the array by if growth is necessary 385 * @throws IllegalArgumentException if {@code minLength} or {@code padding} is negative 386 * @return an array containing the values of {@code array}, with guaranteed minimum length 387 * {@code minLength} 388 */ 389 public static short[] ensureCapacity(short[] array, int minLength, int padding) { 390 checkArgument(minLength >= 0, "Invalid minLength: %s", minLength); 391 checkArgument(padding >= 0, "Invalid padding: %s", padding); 392 return (array.length < minLength) ? Arrays.copyOf(array, minLength + padding) : array; 393 } 394 395 /** 396 * Returns a string containing the supplied {@code short} values separated by {@code separator}. 397 * For example, {@code join("-", (short) 1, (short) 2, 398 * (short) 3)} returns the string {@code "1-2-3"}. 399 * 400 * @param separator the text that should appear between consecutive values in the resulting string 401 * (but not at the start or end) 402 * @param array an array of {@code short} values, possibly empty 403 */ 404 public static String join(String separator, short... array) { 405 checkNotNull(separator); 406 if (array.length == 0) { 407 return ""; 408 } 409 410 // For pre-sizing a builder, just get the right order of magnitude 411 StringBuilder builder = new StringBuilder(array.length * 6); 412 builder.append(array[0]); 413 for (int i = 1; i < array.length; i++) { 414 builder.append(separator).append(array[i]); 415 } 416 return builder.toString(); 417 } 418 419 /** 420 * Returns a comparator that compares two {@code short} arrays <a 421 * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it 422 * compares, using {@link #compare(short, short)}), the first pair of values that follow any 423 * common prefix, or when one array is a prefix of the other, treats the shorter array as the 424 * lesser. For example, {@code [] < [(short) 1] < [(short) 1, (short) 2] < [(short) 2]}. 425 * 426 * <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays 427 * support only identity equality), but it is consistent with 428 * {@link Arrays#equals(short[], short[])}. 429 * 430 * @since 2.0 431 */ 432 public static Comparator<short[]> lexicographicalComparator() { 433 return LexicographicalComparator.INSTANCE; 434 } 435 436 private enum LexicographicalComparator implements Comparator<short[]> { 437 INSTANCE; 438 439 @Override 440 public int compare(short[] left, short[] right) { 441 int minLength = Math.min(left.length, right.length); 442 for (int i = 0; i < minLength; i++) { 443 int result = Shorts.compare(left[i], right[i]); 444 if (result != 0) { 445 return result; 446 } 447 } 448 return left.length - right.length; 449 } 450 451 @Override 452 public String toString() { 453 return "Shorts.lexicographicalComparator()"; 454 } 455 } 456 457 /** 458 * Returns an array containing each value of {@code collection}, converted to a {@code short} 459 * value in the manner of {@link Number#shortValue}. 460 * 461 * <p>Elements are copied from the argument collection as if by {@code 462 * collection.toArray()}. Calling this method is as thread-safe as calling that method. 463 * 464 * @param collection a collection of {@code Number} instances 465 * @return an array containing the same values as {@code collection}, in the same order, converted 466 * to primitives 467 * @throws NullPointerException if {@code collection} or any of its elements is null 468 * @since 1.0 (parameter was {@code Collection<Short>} before 12.0) 469 */ 470 public static short[] toArray(Collection<? extends Number> collection) { 471 if (collection instanceof ShortArrayAsList) { 472 return ((ShortArrayAsList) collection).toShortArray(); 473 } 474 475 Object[] boxedArray = collection.toArray(); 476 int len = boxedArray.length; 477 short[] array = new short[len]; 478 for (int i = 0; i < len; i++) { 479 // checkNotNull for GWT (do not optimize) 480 array[i] = ((Number) checkNotNull(boxedArray[i])).shortValue(); 481 } 482 return array; 483 } 484 485 /** 486 * Returns a fixed-size list backed by the specified array, similar to 487 * {@link Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)}, but any 488 * attempt to set a value to {@code null} will result in a {@link NullPointerException}. 489 * 490 * <p>The returned list maintains the values, but not the identities, of {@code Short} objects 491 * written to or read from it. For example, whether {@code list.get(0) == list.get(0)} is true for 492 * the returned list is unspecified. 493 * 494 * @param backingArray the array to back the list 495 * @return a list view of the array 496 */ 497 public static List<Short> asList(short... backingArray) { 498 if (backingArray.length == 0) { 499 return Collections.emptyList(); 500 } 501 return new ShortArrayAsList(backingArray); 502 } 503 504 @GwtCompatible 505 private static class ShortArrayAsList extends AbstractList<Short> 506 implements RandomAccess, Serializable { 507 final short[] array; 508 final int start; 509 final int end; 510 511 ShortArrayAsList(short[] array) { 512 this(array, 0, array.length); 513 } 514 515 ShortArrayAsList(short[] array, int start, int end) { 516 this.array = array; 517 this.start = start; 518 this.end = end; 519 } 520 521 @Override 522 public int size() { 523 return end - start; 524 } 525 526 @Override 527 public boolean isEmpty() { 528 return false; 529 } 530 531 @Override 532 public Short get(int index) { 533 checkElementIndex(index, size()); 534 return array[start + index]; 535 } 536 537 @Override 538 public boolean contains(Object target) { 539 // Overridden to prevent a ton of boxing 540 return (target instanceof Short) && Shorts.indexOf(array, (Short) target, start, end) != -1; 541 } 542 543 @Override 544 public int indexOf(Object target) { 545 // Overridden to prevent a ton of boxing 546 if (target instanceof Short) { 547 int i = Shorts.indexOf(array, (Short) target, start, end); 548 if (i >= 0) { 549 return i - start; 550 } 551 } 552 return -1; 553 } 554 555 @Override 556 public int lastIndexOf(Object target) { 557 // Overridden to prevent a ton of boxing 558 if (target instanceof Short) { 559 int i = Shorts.lastIndexOf(array, (Short) target, start, end); 560 if (i >= 0) { 561 return i - start; 562 } 563 } 564 return -1; 565 } 566 567 @Override 568 public Short set(int index, Short element) { 569 checkElementIndex(index, size()); 570 short oldValue = array[start + index]; 571 // checkNotNull for GWT (do not optimize) 572 array[start + index] = checkNotNull(element); 573 return oldValue; 574 } 575 576 @Override 577 public List<Short> subList(int fromIndex, int toIndex) { 578 int size = size(); 579 checkPositionIndexes(fromIndex, toIndex, size); 580 if (fromIndex == toIndex) { 581 return Collections.emptyList(); 582 } 583 return new ShortArrayAsList(array, start + fromIndex, start + toIndex); 584 } 585 586 @Override 587 public boolean equals(Object object) { 588 if (object == this) { 589 return true; 590 } 591 if (object instanceof ShortArrayAsList) { 592 ShortArrayAsList that = (ShortArrayAsList) object; 593 int size = size(); 594 if (that.size() != size) { 595 return false; 596 } 597 for (int i = 0; i < size; i++) { 598 if (array[start + i] != that.array[that.start + i]) { 599 return false; 600 } 601 } 602 return true; 603 } 604 return super.equals(object); 605 } 606 607 @Override 608 public int hashCode() { 609 int result = 1; 610 for (int i = start; i < end; i++) { 611 result = 31 * result + Shorts.hashCode(array[i]); 612 } 613 return result; 614 } 615 616 @Override 617 public String toString() { 618 StringBuilder builder = new StringBuilder(size() * 6); 619 builder.append('[').append(array[start]); 620 for (int i = start + 1; i < end; i++) { 621 builder.append(", ").append(array[i]); 622 } 623 return builder.append(']').toString(); 624 } 625 626 short[] toShortArray() { 627 return Arrays.copyOfRange(array, start, end); 628 } 629 630 private static final long serialVersionUID = 0; 631 } 632}