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