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;
034import org.checkerframework.checker.nullness.qual.Nullable;
035
036/**
037 * Static utility methods pertaining to {@code short} primitives, that are not already found in
038 * either {@link Short} or {@link Arrays}.
039 *
040 * <p>See the Guava User Guide article on <a
041 * href="https://github.com/google/guava/wiki/PrimitivesExplained">primitive utilities</a>.
042 *
043 * @author Kevin Bourrillion
044 * @since 1.0
045 */
046@GwtCompatible(emulated = true)
047public final class Shorts {
048  private Shorts() {}
049
050  /**
051   * The number of bytes required to represent a primitive {@code short} value.
052   *
053   * <p><b>Java 8 users:</b> use {@link Short#BYTES} instead.
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 {@code ((Short)
066   * value).hashCode()}.
067   *
068   * <p><b>Java 8 users:</b> use {@link Short#hashCode(short)} instead.
069   *
070   * @param value a primitive {@code short} value
071   * @return a hash code for the value
072   */
073  public static int hashCode(short value) {
074    return value;
075  }
076
077  /**
078   * Returns the {@code short} value that is equal to {@code value}, if possible.
079   *
080   * @param value any value in the range of the {@code short} type
081   * @return the {@code short} value that equals {@code value}
082   * @throws IllegalArgumentException if {@code value} is greater than {@link Short#MAX_VALUE} or
083   *     less than {@link Short#MIN_VALUE}
084   */
085  public static short checkedCast(long value) {
086    short result = (short) value;
087    checkArgument(result == value, "Out of range: %s", value);
088    return result;
089  }
090
091  /**
092   * Returns the {@code short} nearest in value to {@code value}.
093   *
094   * @param value any {@code long} value
095   * @return the same value cast to {@code short} if it is in the range of the {@code short} type,
096   *     {@link Short#MAX_VALUE} if it is too large, 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 returned is the same as
110   * that of {@code ((Short) a).compareTo(b)}.
111   *
112   * <p><b>Note for Java 7 and later:</b> this method should be treated as deprecated; use the
113   * equivalent {@link Short#compare} method instead.
114   *
115   * @param a the first {@code short} to compare
116   * @param b the second {@code short} to compare
117   * @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is
118   *     greater than {@code b}; or zero if they are equal
119   */
120  public static int compare(short a, short b) {
121    return a - b; // safe due to restricted range
122  }
123
124  /**
125   * Returns {@code true} if {@code target} is present as an element anywhere in {@code array}.
126   *
127   * @param array an array of {@code short} values, possibly empty
128   * @param target a primitive {@code short} value
129   * @return {@code true} if {@code array[i] == target} for some value of {@code 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 target} within
164   * {@code array}, or {@code -1} if there is no such occurrence.
165   *
166   * <p>More formally, returns the lowest index {@code i} such that {@code Arrays.copyOfRange(array,
167   * i, i + target.length)} contains exactly the same elements as {@code target}.
168   *
169   * @param array the array to search for the sequence {@code target}
170   * @param target the array to search for as a sub-sequence of {@code array}
171   */
172  public static int indexOf(short[] array, short[] target) {
173    checkNotNull(array, "array");
174    checkNotNull(target, "target");
175    if (target.length == 0) {
176      return 0;
177    }
178
179    outer:
180    for (int i = 0; i < array.length - target.length + 1; i++) {
181      for (int j = 0; j < target.length; j++) {
182        if (array[i + j] != target[j]) {
183          continue outer;
184        }
185      }
186      return i;
187    }
188    return -1;
189  }
190
191  /**
192   * Returns the index of the last appearance of the value {@code target} in {@code array}.
193   *
194   * @param array an array of {@code short} values, possibly empty
195   * @param target a primitive {@code short} value
196   * @return the greatest index {@code i} for which {@code array[i] == target}, or {@code -1} if no
197   *     such index exists.
198   */
199  public static int lastIndexOf(short[] array, short target) {
200    return lastIndexOf(array, target, 0, array.length);
201  }
202
203  // TODO(kevinb): consider making this public
204  private static int lastIndexOf(short[] array, short target, int start, int end) {
205    for (int i = end - 1; i >= start; i--) {
206      if (array[i] == target) {
207        return i;
208      }
209    }
210    return -1;
211  }
212
213  /**
214   * Returns the least value present in {@code array}.
215   *
216   * @param array a <i>nonempty</i> array of {@code short} values
217   * @return the value present in {@code array} that is less than or equal to every other value in
218   *     the array
219   * @throws IllegalArgumentException if {@code array} is empty
220   */
221  public static short min(short... array) {
222    checkArgument(array.length > 0);
223    short min = array[0];
224    for (int i = 1; i < array.length; i++) {
225      if (array[i] < min) {
226        min = array[i];
227      }
228    }
229    return min;
230  }
231
232  /**
233   * Returns the greatest value present in {@code array}.
234   *
235   * @param array a <i>nonempty</i> array of {@code short} values
236   * @return the value present in {@code array} that is greater than or equal to every other value
237   *     in the array
238   * @throws IllegalArgumentException if {@code array} is empty
239   */
240  public static short max(short... array) {
241    checkArgument(array.length > 0);
242    short max = array[0];
243    for (int i = 1; i < array.length; i++) {
244      if (array[i] > max) {
245        max = array[i];
246      }
247    }
248    return max;
249  }
250
251  /**
252   * Returns the value nearest to {@code value} which is within the closed range {@code [min..max]}.
253   *
254   * <p>If {@code value} is within the range {@code [min..max]}, {@code value} is returned
255   * unchanged. If {@code value} is less than {@code min}, {@code min} is returned, and if {@code
256   * value} is greater than {@code max}, {@code max} is returned.
257   *
258   * @param value the {@code short} value to constrain
259   * @param min the lower bound (inclusive) of the range to constrain {@code value} to
260   * @param max the upper bound (inclusive) of the range to constrain {@code value} to
261   * @throws IllegalArgumentException if {@code min > max}
262   * @since 21.0
263   */
264  @Beta
265  public static short constrainToRange(short value, short min, short max) {
266    checkArgument(min <= max, "min (%s) must be less than or equal to max (%s)", min, max);
267    return value < min ? min : value < max ? value : max;
268  }
269
270  /**
271   * Returns the values from each provided array combined into a single array. For example, {@code
272   * concat(new short[] {a, b}, new short[] {}, new short[] {c}} returns the array {@code {a, b,
273   * c}}.
274   *
275   * @param arrays zero or more {@code short} arrays
276   * @return a single array containing all the values from the source arrays, in order
277   */
278  public static short[] concat(short[]... arrays) {
279    int length = 0;
280    for (short[] array : arrays) {
281      length += array.length;
282    }
283    short[] result = new short[length];
284    int pos = 0;
285    for (short[] array : arrays) {
286      System.arraycopy(array, 0, result, pos, array.length);
287      pos += array.length;
288    }
289    return result;
290  }
291
292  /**
293   * Returns a big-endian representation of {@code value} in a 2-element byte array; equivalent to
294   * {@code ByteBuffer.allocate(2).putShort(value).array()}. For example, the input value {@code
295   * (short) 0x1234} would yield the byte array {@code {0x12, 0x34}}.
296   *
297   * <p>If you need to convert and concatenate several values (possibly even of different types),
298   * use a shared {@link java.nio.ByteBuffer} instance, or use {@link
299   * com.google.common.io.ByteStreams#newDataOutput()} to get a growable buffer.
300   */
301  @GwtIncompatible // doesn't work
302  public static byte[] toByteArray(short value) {
303    return new byte[] {(byte) (value >> 8), (byte) value};
304  }
305
306  /**
307   * Returns the {@code short} value whose big-endian representation is stored in the first 2 bytes
308   * of {@code bytes}; equivalent to {@code ByteBuffer.wrap(bytes).getShort()}. For example, the
309   * input byte array {@code {0x54, 0x32}} would yield the {@code short} value {@code 0x5432}.
310   *
311   * <p>Arguably, it's preferable to use {@link java.nio.ByteBuffer}; that library exposes much more
312   * flexibility at little cost in readability.
313   *
314   * @throws IllegalArgumentException if {@code bytes} has fewer than 2 elements
315   */
316  @GwtIncompatible // doesn't work
317  public static short fromByteArray(byte[] bytes) {
318    checkArgument(bytes.length >= BYTES, "array too small: %s < %s", bytes.length, BYTES);
319    return fromBytes(bytes[0], bytes[1]);
320  }
321
322  /**
323   * Returns the {@code short} value whose byte representation is the given 2 bytes, in big-endian
324   * order; equivalent to {@code Shorts.fromByteArray(new byte[] {b1, b2})}.
325   *
326   * @since 7.0
327   */
328  @GwtIncompatible // doesn't work
329  public static short fromBytes(byte b1, byte b2) {
330    return (short) ((b1 << 8) | (b2 & 0xFF));
331  }
332
333  private static final class ShortConverter extends Converter<String, Short>
334      implements Serializable {
335    static final ShortConverter INSTANCE = new ShortConverter();
336
337    @Override
338    protected Short doForward(String value) {
339      return Short.decode(value);
340    }
341
342    @Override
343    protected String doBackward(Short value) {
344      return value.toString();
345    }
346
347    @Override
348    public String toString() {
349      return "Shorts.stringConverter()";
350    }
351
352    private Object readResolve() {
353      return INSTANCE;
354    }
355
356    private static final long serialVersionUID = 1;
357  }
358
359  /**
360   * Returns a serializable converter object that converts between strings and shorts using {@link
361   * Short#decode} and {@link Short#toString()}. The returned converter throws {@link
362   * NumberFormatException} if the input string is invalid.
363   *
364   * <p><b>Warning:</b> please see {@link Short#decode} to understand exactly how strings are
365   * parsed. For example, the string {@code "0123"} is treated as <i>octal</i> and converted to the
366   * value {@code 83}.
367   *
368   * @since 16.0
369   */
370  @Beta
371  public static Converter<String, Short> stringConverter() {
372    return ShortConverter.INSTANCE;
373  }
374
375  /**
376   * Returns an array containing the same values as {@code array}, but guaranteed to be of a
377   * specified minimum length. If {@code array} already has a length of at least {@code minLength},
378   * it is returned directly. Otherwise, a new array of size {@code minLength + padding} is
379   * returned, containing the values of {@code array}, and zeroes in the remaining places.
380   *
381   * @param array the source array
382   * @param minLength the minimum length the returned array must guarantee
383   * @param padding an extra amount to "grow" the array by if growth is necessary
384   * @throws IllegalArgumentException if {@code minLength} or {@code padding} is negative
385   * @return an array containing the values of {@code array}, with guaranteed minimum length {@code
386   *     minLength}
387   */
388  public static short[] ensureCapacity(short[] array, int minLength, int padding) {
389    checkArgument(minLength >= 0, "Invalid minLength: %s", minLength);
390    checkArgument(padding >= 0, "Invalid padding: %s", padding);
391    return (array.length < minLength) ? Arrays.copyOf(array, minLength + padding) : array;
392  }
393
394  /**
395   * Returns a string containing the supplied {@code short} values separated by {@code separator}.
396   * For example, {@code join("-", (short) 1, (short) 2, (short) 3)} returns the string {@code
397   * "1-2-3"}.
398   *
399   * @param separator the text that should appear between consecutive values in the resulting string
400   *     (but not at the start or end)
401   * @param array an array of {@code short} values, possibly empty
402   */
403  public static String join(String separator, short... array) {
404    checkNotNull(separator);
405    if (array.length == 0) {
406      return "";
407    }
408
409    // For pre-sizing a builder, just get the right order of magnitude
410    StringBuilder builder = new StringBuilder(array.length * 6);
411    builder.append(array[0]);
412    for (int i = 1; i < array.length; i++) {
413      builder.append(separator).append(array[i]);
414    }
415    return builder.toString();
416  }
417
418  /**
419   * Returns a comparator that compares two {@code short} arrays <a
420   * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it
421   * compares, using {@link #compare(short, short)}), the first pair of values that follow any
422   * common prefix, or when one array is a prefix of the other, treats the shorter array as the
423   * lesser. For example, {@code [] < [(short) 1] < [(short) 1, (short) 2] < [(short) 2]}.
424   *
425   * <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays
426   * support only identity equality), but it is consistent with {@link Arrays#equals(short[],
427   * short[])}.
428   *
429   * @since 2.0
430   */
431  public static Comparator<short[]> lexicographicalComparator() {
432    return LexicographicalComparator.INSTANCE;
433  }
434
435  private enum LexicographicalComparator implements Comparator<short[]> {
436    INSTANCE;
437
438    @Override
439    public int compare(short[] left, short[] right) {
440      int minLength = Math.min(left.length, right.length);
441      for (int i = 0; i < minLength; i++) {
442        int result = Shorts.compare(left[i], right[i]);
443        if (result != 0) {
444          return result;
445        }
446      }
447      return left.length - right.length;
448    }
449
450    @Override
451    public String toString() {
452      return "Shorts.lexicographicalComparator()";
453    }
454  }
455
456  /**
457   * Sorts the elements of {@code array} in descending order.
458   *
459   * @since 23.1
460   */
461  public static void sortDescending(short[] array) {
462    checkNotNull(array);
463    sortDescending(array, 0, array.length);
464  }
465
466  /**
467   * Sorts the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex}
468   * exclusive in descending order.
469   *
470   * @since 23.1
471   */
472  public static void sortDescending(short[] array, int fromIndex, int toIndex) {
473    checkNotNull(array);
474    checkPositionIndexes(fromIndex, toIndex, array.length);
475    Arrays.sort(array, fromIndex, toIndex);
476    reverse(array, fromIndex, toIndex);
477  }
478
479  /**
480   * Reverses the elements of {@code array}. This is equivalent to {@code
481   * Collections.reverse(Shorts.asList(array))}, but is likely to be more efficient.
482   *
483   * @since 23.1
484   */
485  public static void reverse(short[] array) {
486    checkNotNull(array);
487    reverse(array, 0, array.length);
488  }
489
490  /**
491   * Reverses the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex}
492   * exclusive. This is equivalent to {@code
493   * Collections.reverse(Shorts.asList(array).subList(fromIndex, toIndex))}, but is likely to be
494   * more efficient.
495   *
496   * @throws IndexOutOfBoundsException if {@code fromIndex < 0}, {@code toIndex > array.length}, or
497   *     {@code toIndex > fromIndex}
498   * @since 23.1
499   */
500  public static void reverse(short[] array, int fromIndex, int toIndex) {
501    checkNotNull(array);
502    checkPositionIndexes(fromIndex, toIndex, array.length);
503    for (int i = fromIndex, j = toIndex - 1; i < j; i++, j--) {
504      short tmp = array[i];
505      array[i] = array[j];
506      array[j] = tmp;
507    }
508  }
509
510  /**
511   * Returns an array containing each value of {@code collection}, converted to a {@code short}
512   * value in the manner of {@link Number#shortValue}.
513   *
514   * <p>Elements are copied from the argument collection as if by {@code collection.toArray()}.
515   * Calling this method is as thread-safe as calling that method.
516   *
517   * @param collection a collection of {@code Number} instances
518   * @return an array containing the same values as {@code collection}, in the same order, converted
519   *     to primitives
520   * @throws NullPointerException if {@code collection} or any of its elements is null
521   * @since 1.0 (parameter was {@code Collection<Short>} before 12.0)
522   */
523  public static short[] toArray(Collection<? extends Number> collection) {
524    if (collection instanceof ShortArrayAsList) {
525      return ((ShortArrayAsList) collection).toShortArray();
526    }
527
528    Object[] boxedArray = collection.toArray();
529    int len = boxedArray.length;
530    short[] array = new short[len];
531    for (int i = 0; i < len; i++) {
532      // checkNotNull for GWT (do not optimize)
533      array[i] = ((Number) checkNotNull(boxedArray[i])).shortValue();
534    }
535    return array;
536  }
537
538  /**
539   * Returns a fixed-size list backed by the specified array, similar to {@link
540   * Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)}, but any attempt to
541   * set a value to {@code null} will result in a {@link NullPointerException}.
542   *
543   * <p>The returned list maintains the values, but not the identities, of {@code Short} objects
544   * written to or read from it. For example, whether {@code list.get(0) == list.get(0)} is true for
545   * the returned list is unspecified.
546   *
547   * @param backingArray the array to back the list
548   * @return a list view of the array
549   */
550  public static List<Short> asList(short... backingArray) {
551    if (backingArray.length == 0) {
552      return Collections.emptyList();
553    }
554    return new ShortArrayAsList(backingArray);
555  }
556
557  @GwtCompatible
558  private static class ShortArrayAsList extends AbstractList<Short>
559      implements RandomAccess, Serializable {
560    final short[] array;
561    final int start;
562    final int end;
563
564    ShortArrayAsList(short[] array) {
565      this(array, 0, array.length);
566    }
567
568    ShortArrayAsList(short[] array, int start, int end) {
569      this.array = array;
570      this.start = start;
571      this.end = end;
572    }
573
574    @Override
575    public int size() {
576      return end - start;
577    }
578
579    @Override
580    public boolean isEmpty() {
581      return false;
582    }
583
584    @Override
585    public Short get(int index) {
586      checkElementIndex(index, size());
587      return array[start + index];
588    }
589
590    @Override
591    public boolean contains(@Nullable Object target) {
592      // Overridden to prevent a ton of boxing
593      return (target instanceof Short) && Shorts.indexOf(array, (Short) target, start, end) != -1;
594    }
595
596    @Override
597    public int indexOf(@Nullable Object target) {
598      // Overridden to prevent a ton of boxing
599      if (target instanceof Short) {
600        int i = Shorts.indexOf(array, (Short) target, start, end);
601        if (i >= 0) {
602          return i - start;
603        }
604      }
605      return -1;
606    }
607
608    @Override
609    public int lastIndexOf(@Nullable Object target) {
610      // Overridden to prevent a ton of boxing
611      if (target instanceof Short) {
612        int i = Shorts.lastIndexOf(array, (Short) target, start, end);
613        if (i >= 0) {
614          return i - start;
615        }
616      }
617      return -1;
618    }
619
620    @Override
621    public Short set(int index, Short element) {
622      checkElementIndex(index, size());
623      short oldValue = array[start + index];
624      // checkNotNull for GWT (do not optimize)
625      array[start + index] = checkNotNull(element);
626      return oldValue;
627    }
628
629    @Override
630    public List<Short> subList(int fromIndex, int toIndex) {
631      int size = size();
632      checkPositionIndexes(fromIndex, toIndex, size);
633      if (fromIndex == toIndex) {
634        return Collections.emptyList();
635      }
636      return new ShortArrayAsList(array, start + fromIndex, start + toIndex);
637    }
638
639    @Override
640    public boolean equals(@Nullable Object object) {
641      if (object == this) {
642        return true;
643      }
644      if (object instanceof ShortArrayAsList) {
645        ShortArrayAsList that = (ShortArrayAsList) object;
646        int size = size();
647        if (that.size() != size) {
648          return false;
649        }
650        for (int i = 0; i < size; i++) {
651          if (array[start + i] != that.array[that.start + i]) {
652            return false;
653          }
654        }
655        return true;
656      }
657      return super.equals(object);
658    }
659
660    @Override
661    public int hashCode() {
662      int result = 1;
663      for (int i = start; i < end; i++) {
664        result = 31 * result + Shorts.hashCode(array[i]);
665      }
666      return result;
667    }
668
669    @Override
670    public String toString() {
671      StringBuilder builder = new StringBuilder(size() * 6);
672      builder.append('[').append(array[start]);
673      for (int i = start + 1; i < end; i++) {
674        builder.append(", ").append(array[i]);
675      }
676      return builder.append(']').toString();
677    }
678
679    short[] toShortArray() {
680      return Arrays.copyOfRange(array, start, end);
681    }
682
683    private static final long serialVersionUID = 0;
684  }
685}