1 /*
2 * Copyright (C) 2008 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5 * in compliance with the License. You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software distributed under the License
10 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
11 * or implied. See the License for the specific language governing permissions and limitations under
12 * the License.
13 */
14
15 package com.google.common.primitives;
16
17 import static com.google.common.base.Preconditions.checkArgument;
18 import static com.google.common.base.Preconditions.checkElementIndex;
19 import static com.google.common.base.Preconditions.checkNotNull;
20 import static com.google.common.base.Preconditions.checkPositionIndexes;
21
22 import com.google.common.annotations.Beta;
23 import com.google.common.annotations.GwtCompatible;
24 import com.google.common.annotations.GwtIncompatible;
25 import com.google.common.base.Converter;
26 import java.io.Serializable;
27 import java.util.AbstractList;
28 import java.util.Arrays;
29 import java.util.Collection;
30 import java.util.Collections;
31 import java.util.Comparator;
32 import java.util.List;
33 import java.util.RandomAccess;
34 import javax.annotation.CheckForNull;
35
36 /**
37 * Static utility methods pertaining to {@code short} primitives, that are not already found in
38 * either {@link Short} or {@link Arrays}.
39 *
40 * <p>See the Guava User Guide article on <a
41 * href="https://github.com/google/guava/wiki/PrimitivesExplained">primitive utilities</a>.
42 *
43 * @author Kevin Bourrillion
44 * @since 1.0
45 */
46 @GwtCompatible(emulated = true)
47 @ElementTypesAreNonnullByDefault
48 public final class Shorts extends ShortsMethodsForWeb {
49 private Shorts() {}
50
51 /**
52 * The number of bytes required to represent a primitive {@code short} value.
53 *
54 * <p><b>Java 8 users:</b> use {@link Short#BYTES} instead.
55 */
56 public static final int BYTES = Short.SIZE / Byte.SIZE;
57
58 /**
59 * The largest power of two that can be represented as a {@code short}.
60 *
61 * @since 10.0
62 */
63 public static final short MAX_POWER_OF_TWO = 1 << (Short.SIZE - 2);
64
65 /**
66 * Returns a hash code for {@code value}; equal to the result of invoking {@code ((Short)
67 * value).hashCode()}.
68 *
69 * <p><b>Java 8 users:</b> use {@link Short#hashCode(short)} instead.
70 *
71 * @param value a primitive {@code short} value
72 * @return a hash code for the value
73 */
74 public static int hashCode(short value) {
75 return value;
76 }
77
78 /**
79 * Returns the {@code short} value that is equal to {@code value}, if possible.
80 *
81 * @param value any value in the range of the {@code short} type
82 * @return the {@code short} value that equals {@code value}
83 * @throws IllegalArgumentException if {@code value} is greater than {@link Short#MAX_VALUE} or
84 * less than {@link Short#MIN_VALUE}
85 */
86 public static short checkedCast(long value) {
87 short result = (short) value;
88 checkArgument(result == value, "Out of range: %s", value);
89 return result;
90 }
91
92 /**
93 * Returns the {@code short} nearest in value to {@code value}.
94 *
95 * @param value any {@code long} value
96 * @return the same value cast to {@code short} if it is in the range of the {@code short} type,
97 * {@link Short#MAX_VALUE} if it is too large, or {@link Short#MIN_VALUE} if it is too small
98 */
99 public static short saturatedCast(long value) {
100 if (value > Short.MAX_VALUE) {
101 return Short.MAX_VALUE;
102 }
103 if (value < Short.MIN_VALUE) {
104 return Short.MIN_VALUE;
105 }
106 return (short) value;
107 }
108
109 /**
110 * Compares the two specified {@code short} values. The sign of the value returned is the same as
111 * that of {@code ((Short) a).compareTo(b)}.
112 *
113 * <p><b>Note for Java 7 and later:</b> this method should be treated as deprecated; use the
114 * equivalent {@link Short#compare} method instead.
115 *
116 * @param a the first {@code short} to compare
117 * @param b the second {@code short} to compare
118 * @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is
119 * greater than {@code b}; or zero if they are equal
120 */
121 public static int compare(short a, short b) {
122 return a - b; // safe due to restricted range
123 }
124
125 /**
126 * Returns {@code true} if {@code target} is present as an element anywhere in {@code array}.
127 *
128 * @param array an array of {@code short} values, possibly empty
129 * @param target a primitive {@code short} value
130 * @return {@code true} if {@code array[i] == target} for some value of {@code i}
131 */
132 public static boolean contains(short[] array, short target) {
133 for (short value : array) {
134 if (value == target) {
135 return true;
136 }
137 }
138 return false;
139 }
140
141 /**
142 * Returns the index of the first appearance of the value {@code target} in {@code array}.
143 *
144 * @param array an array of {@code short} values, possibly empty
145 * @param target a primitive {@code short} value
146 * @return the least index {@code i} for which {@code array[i] == target}, or {@code -1} if no
147 * such index exists.
148 */
149 public static int indexOf(short[] array, short target) {
150 return indexOf(array, target, 0, array.length);
151 }
152
153 // TODO(kevinb): consider making this public
154 private static int indexOf(short[] array, short target, int start, int end) {
155 for (int i = start; i < end; i++) {
156 if (array[i] == target) {
157 return i;
158 }
159 }
160 return -1;
161 }
162
163 /**
164 * Returns the start position of the first occurrence of the specified {@code target} within
165 * {@code array}, or {@code -1} if there is no such occurrence.
166 *
167 * <p>More formally, returns the lowest index {@code i} such that {@code Arrays.copyOfRange(array,
168 * i, i + target.length)} contains exactly the same elements as {@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 @GwtIncompatible(
223 "Available in GWT! Annotation is to avoid conflict with GWT specialization of base class.")
224 public static short min(short... array) {
225 checkArgument(array.length > 0);
226 short min = array[0];
227 for (int i = 1; i < array.length; i++) {
228 if (array[i] < min) {
229 min = array[i];
230 }
231 }
232 return min;
233 }
234
235 /**
236 * Returns the greatest value present in {@code array}.
237 *
238 * @param array a <i>nonempty</i> array of {@code short} values
239 * @return the value present in {@code array} that is greater than or equal to every other value
240 * in the array
241 * @throws IllegalArgumentException if {@code array} is empty
242 */
243 @GwtIncompatible(
244 "Available in GWT! Annotation is to avoid conflict with GWT specialization of base class.")
245 public static short max(short... array) {
246 checkArgument(array.length > 0);
247 short max = array[0];
248 for (int i = 1; i < array.length; i++) {
249 if (array[i] > max) {
250 max = array[i];
251 }
252 }
253 return max;
254 }
255
256 /**
257 * Returns the value nearest to {@code value} which is within the closed range {@code [min..max]}.
258 *
259 * <p>If {@code value} is within the range {@code [min..max]}, {@code value} is returned
260 * unchanged. If {@code value} is less than {@code min}, {@code min} is returned, and if {@code
261 * value} is greater than {@code max}, {@code max} is returned.
262 *
263 * @param value the {@code short} value to constrain
264 * @param min the lower bound (inclusive) of the range to constrain {@code value} to
265 * @param max the upper bound (inclusive) of the range to constrain {@code value} to
266 * @throws IllegalArgumentException if {@code min > max}
267 * @since 21.0
268 */
269 @Beta
270 public static short constrainToRange(short value, short min, short max) {
271 checkArgument(min <= max, "min (%s) must be less than or equal to max (%s)", min, max);
272 return value < min ? min : value < max ? value : max;
273 }
274
275 /**
276 * Returns the values from each provided array combined into a single array. For example, {@code
277 * concat(new short[] {a, b}, new short[] {}, new short[] {c}} returns the array {@code {a, b,
278 * c}}.
279 *
280 * @param arrays zero or more {@code short} arrays
281 * @return a single array containing all the values from the source arrays, in order
282 */
283 public static short[] concat(short[]... arrays) {
284 int length = 0;
285 for (short[] array : arrays) {
286 length += array.length;
287 }
288 short[] result = new short[length];
289 int pos = 0;
290 for (short[] array : arrays) {
291 System.arraycopy(array, 0, result, pos, array.length);
292 pos += array.length;
293 }
294 return result;
295 }
296
297 /**
298 * Returns a big-endian representation of {@code value} in a 2-element byte array; equivalent to
299 * {@code ByteBuffer.allocate(2).putShort(value).array()}. For example, the input value {@code
300 * (short) 0x1234} would yield the byte array {@code {0x12, 0x34}}.
301 *
302 * <p>If you need to convert and concatenate several values (possibly even of different types),
303 * use a shared {@link java.nio.ByteBuffer} instance, or use {@link
304 * com.google.common.io.ByteStreams#newDataOutput()} to get a growable buffer.
305 */
306 @GwtIncompatible // doesn't work
307 public static byte[] toByteArray(short value) {
308 return new byte[] {(byte) (value >> 8), (byte) value};
309 }
310
311 /**
312 * Returns the {@code short} value whose big-endian representation is stored in the first 2 bytes
313 * of {@code bytes}; equivalent to {@code ByteBuffer.wrap(bytes).getShort()}. For example, the
314 * input byte array {@code {0x54, 0x32}} would yield the {@code short} value {@code 0x5432}.
315 *
316 * <p>Arguably, it's preferable to use {@link java.nio.ByteBuffer}; that library exposes much more
317 * flexibility at little cost in readability.
318 *
319 * @throws IllegalArgumentException if {@code bytes} has fewer than 2 elements
320 */
321 @GwtIncompatible // doesn't work
322 public static short fromByteArray(byte[] bytes) {
323 checkArgument(bytes.length >= BYTES, "array too small: %s < %s", bytes.length, BYTES);
324 return fromBytes(bytes[0], bytes[1]);
325 }
326
327 /**
328 * Returns the {@code short} value whose byte representation is the given 2 bytes, in big-endian
329 * order; equivalent to {@code Shorts.fromByteArray(new byte[] {b1, b2})}.
330 *
331 * @since 7.0
332 */
333 @GwtIncompatible // doesn't work
334 public static short fromBytes(byte b1, byte b2) {
335 return (short) ((b1 << 8) | (b2 & 0xFF));
336 }
337
338 private static final class ShortConverter extends Converter<String, Short>
339 implements Serializable {
340 static final ShortConverter INSTANCE = new ShortConverter();
341
342 @Override
343 protected Short doForward(String value) {
344 return Short.decode(value);
345 }
346
347 @Override
348 protected String doBackward(Short value) {
349 return value.toString();
350 }
351
352 @Override
353 public String toString() {
354 return "Shorts.stringConverter()";
355 }
356
357 private Object readResolve() {
358 return INSTANCE;
359 }
360
361 private static final long serialVersionUID = 1;
362 }
363
364 /**
365 * Returns a serializable converter object that converts between strings and shorts using {@link
366 * Short#decode} and {@link Short#toString()}. The returned converter throws {@link
367 * NumberFormatException} if the input string is invalid.
368 *
369 * <p><b>Warning:</b> please see {@link Short#decode} to understand exactly how strings are
370 * parsed. For example, the string {@code "0123"} is treated as <i>octal</i> and converted to the
371 * value {@code 83}.
372 *
373 * @since 16.0
374 */
375 @Beta
376 public static Converter<String, Short> stringConverter() {
377 return ShortConverter.INSTANCE;
378 }
379
380 /**
381 * Returns an array containing the same values as {@code array}, but guaranteed to be of a
382 * specified minimum length. If {@code array} already has a length of at least {@code minLength},
383 * it is returned directly. Otherwise, a new array of size {@code minLength + padding} is
384 * returned, containing the values of {@code array}, and zeroes in the remaining places.
385 *
386 * @param array the source array
387 * @param minLength the minimum length the returned array must guarantee
388 * @param padding an extra amount to "grow" the array by if growth is necessary
389 * @throws IllegalArgumentException if {@code minLength} or {@code padding} is negative
390 * @return an array containing the values of {@code array}, with guaranteed minimum length {@code
391 * minLength}
392 */
393 public static short[] ensureCapacity(short[] array, int minLength, int padding) {
394 checkArgument(minLength >= 0, "Invalid minLength: %s", minLength);
395 checkArgument(padding >= 0, "Invalid padding: %s", padding);
396 return (array.length < minLength) ? Arrays.copyOf(array, minLength + padding) : array;
397 }
398
399 /**
400 * Returns a string containing the supplied {@code short} values separated by {@code separator}.
401 * For example, {@code join("-", (short) 1, (short) 2, (short) 3)} returns the string {@code
402 * "1-2-3"}.
403 *
404 * @param separator the text that should appear between consecutive values in the resulting string
405 * (but not at the start or end)
406 * @param array an array of {@code short} values, possibly empty
407 */
408 public static String join(String separator, short... array) {
409 checkNotNull(separator);
410 if (array.length == 0) {
411 return "";
412 }
413
414 // For pre-sizing a builder, just get the right order of magnitude
415 StringBuilder builder = new StringBuilder(array.length * 6);
416 builder.append(array[0]);
417 for (int i = 1; i < array.length; i++) {
418 builder.append(separator).append(array[i]);
419 }
420 return builder.toString();
421 }
422
423 /**
424 * Returns a comparator that compares two {@code short} arrays <a
425 * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it
426 * compares, using {@link #compare(short, short)}), the first pair of values that follow any
427 * common prefix, or when one array is a prefix of the other, treats the shorter array as the
428 * lesser. For example, {@code [] < [(short) 1] < [(short) 1, (short) 2] < [(short) 2]}.
429 *
430 * <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays
431 * support only identity equality), but it is consistent with {@link Arrays#equals(short[],
432 * short[])}.
433 *
434 * @since 2.0
435 */
436 public static Comparator<short[]> lexicographicalComparator() {
437 return LexicographicalComparator.INSTANCE;
438 }
439
440 private enum LexicographicalComparator implements Comparator<short[]> {
441 INSTANCE;
442
443 @Override
444 public int compare(short[] left, short[] right) {
445 int minLength = Math.min(left.length, right.length);
446 for (int i = 0; i < minLength; i++) {
447 int result = Shorts.compare(left[i], right[i]);
448 if (result != 0) {
449 return result;
450 }
451 }
452 return left.length - right.length;
453 }
454
455 @Override
456 public String toString() {
457 return "Shorts.lexicographicalComparator()";
458 }
459 }
460
461 /**
462 * Sorts the elements of {@code array} in descending order.
463 *
464 * @since 23.1
465 */
466 public static void sortDescending(short[] array) {
467 checkNotNull(array);
468 sortDescending(array, 0, array.length);
469 }
470
471 /**
472 * Sorts the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex}
473 * exclusive in descending order.
474 *
475 * @since 23.1
476 */
477 public static void sortDescending(short[] array, int fromIndex, int toIndex) {
478 checkNotNull(array);
479 checkPositionIndexes(fromIndex, toIndex, array.length);
480 Arrays.sort(array, fromIndex, toIndex);
481 reverse(array, fromIndex, toIndex);
482 }
483
484 /**
485 * Reverses the elements of {@code array}. This is equivalent to {@code
486 * Collections.reverse(Shorts.asList(array))}, but is likely to be more efficient.
487 *
488 * @since 23.1
489 */
490 public static void reverse(short[] array) {
491 checkNotNull(array);
492 reverse(array, 0, array.length);
493 }
494
495 /**
496 * Reverses the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex}
497 * exclusive. This is equivalent to {@code
498 * Collections.reverse(Shorts.asList(array).subList(fromIndex, toIndex))}, but is likely to be
499 * more efficient.
500 *
501 * @throws IndexOutOfBoundsException if {@code fromIndex < 0}, {@code toIndex > array.length}, or
502 * {@code toIndex > fromIndex}
503 * @since 23.1
504 */
505 public static void reverse(short[] array, int fromIndex, int toIndex) {
506 checkNotNull(array);
507 checkPositionIndexes(fromIndex, toIndex, array.length);
508 for (int i = fromIndex, j = toIndex - 1; i < j; i++, j--) {
509 short tmp = array[i];
510 array[i] = array[j];
511 array[j] = tmp;
512 }
513 }
514
515 /**
516 * Returns an array containing each value of {@code collection}, converted to a {@code short}
517 * value in the manner of {@link Number#shortValue}.
518 *
519 * <p>Elements are copied from the argument collection as if by {@code collection.toArray()}.
520 * Calling this method is as thread-safe as calling that method.
521 *
522 * @param collection a collection of {@code Number} instances
523 * @return an array containing the same values as {@code collection}, in the same order, converted
524 * to primitives
525 * @throws NullPointerException if {@code collection} or any of its elements is null
526 * @since 1.0 (parameter was {@code Collection<Short>} before 12.0)
527 */
528 public static short[] toArray(Collection<? extends Number> collection) {
529 if (collection instanceof ShortArrayAsList) {
530 return ((ShortArrayAsList) collection).toShortArray();
531 }
532
533 Object[] boxedArray = collection.toArray();
534 int len = boxedArray.length;
535 short[] array = new short[len];
536 for (int i = 0; i < len; i++) {
537 // checkNotNull for GWT (do not optimize)
538 array[i] = ((Number) checkNotNull(boxedArray[i])).shortValue();
539 }
540 return array;
541 }
542
543 /**
544 * Returns a fixed-size list backed by the specified array, similar to {@link
545 * Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)}, but any attempt to
546 * set a value to {@code null} will result in a {@link NullPointerException}.
547 *
548 * <p>The returned list maintains the values, but not the identities, of {@code Short} objects
549 * written to or read from it. For example, whether {@code list.get(0) == list.get(0)} is true for
550 * the returned list is unspecified.
551 *
552 * @param backingArray the array to back the list
553 * @return a list view of the array
554 */
555 public static List<Short> asList(short... backingArray) {
556 if (backingArray.length == 0) {
557 return Collections.emptyList();
558 }
559 return new ShortArrayAsList(backingArray);
560 }
561
562 @GwtCompatible
563 private static class ShortArrayAsList extends AbstractList<Short>
564 implements RandomAccess, Serializable {
565 final short[] array;
566 final int start;
567 final int end;
568
569 ShortArrayAsList(short[] array) {
570 this(array, 0, array.length);
571 }
572
573 ShortArrayAsList(short[] array, int start, int end) {
574 this.array = array;
575 this.start = start;
576 this.end = end;
577 }
578
579 @Override
580 public int size() {
581 return end - start;
582 }
583
584 @Override
585 public boolean isEmpty() {
586 return false;
587 }
588
589 @Override
590 public Short get(int index) {
591 checkElementIndex(index, size());
592 return array[start + index];
593 }
594
595 @Override
596 public boolean contains(@CheckForNull Object target) {
597 // Overridden to prevent a ton of boxing
598 return (target instanceof Short) && Shorts.indexOf(array, (Short) target, start, end) != -1;
599 }
600
601 @Override
602 public int indexOf(@CheckForNull Object target) {
603 // Overridden to prevent a ton of boxing
604 if (target instanceof Short) {
605 int i = Shorts.indexOf(array, (Short) target, start, end);
606 if (i >= 0) {
607 return i - start;
608 }
609 }
610 return -1;
611 }
612
613 @Override
614 public int lastIndexOf(@CheckForNull Object target) {
615 // Overridden to prevent a ton of boxing
616 if (target instanceof Short) {
617 int i = Shorts.lastIndexOf(array, (Short) target, start, end);
618 if (i >= 0) {
619 return i - start;
620 }
621 }
622 return -1;
623 }
624
625 @Override
626 public Short set(int index, Short element) {
627 checkElementIndex(index, size());
628 short oldValue = array[start + index];
629 // checkNotNull for GWT (do not optimize)
630 array[start + index] = checkNotNull(element);
631 return oldValue;
632 }
633
634 @Override
635 public List<Short> subList(int fromIndex, int toIndex) {
636 int size = size();
637 checkPositionIndexes(fromIndex, toIndex, size);
638 if (fromIndex == toIndex) {
639 return Collections.emptyList();
640 }
641 return new ShortArrayAsList(array, start + fromIndex, start + toIndex);
642 }
643
644 @Override
645 public boolean equals(@CheckForNull Object object) {
646 if (object == this) {
647 return true;
648 }
649 if (object instanceof ShortArrayAsList) {
650 ShortArrayAsList that = (ShortArrayAsList) object;
651 int size = size();
652 if (that.size() != size) {
653 return false;
654 }
655 for (int i = 0; i < size; i++) {
656 if (array[start + i] != that.array[that.start + i]) {
657 return false;
658 }
659 }
660 return true;
661 }
662 return super.equals(object);
663 }
664
665 @Override
666 public int hashCode() {
667 int result = 1;
668 for (int i = start; i < end; i++) {
669 result = 31 * result + Shorts.hashCode(array[i]);
670 }
671 return result;
672 }
673
674 @Override
675 public String toString() {
676 StringBuilder builder = new StringBuilder(size() * 6);
677 builder.append('[').append(array[start]);
678 for (int i = start + 1; i < end; i++) {
679 builder.append(", ").append(array[i]);
680 }
681 return builder.append(']').toString();
682 }
683
684 short[] toShortArray() {
685 return Arrays.copyOfRange(array, start, end);
686 }
687
688 private static final long serialVersionUID = 0;
689 }
690 }