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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  
35  /**
36   * Static utility methods pertaining to {@code short} primitives, that are not already found in
37   * either {@link Short} or {@link Arrays}.
38   *
39   * <p>See the Guava User Guide article on
40   * <a href="https://github.com/google/guava/wiki/PrimitivesExplained">primitive utilities</a>.
41   *
42   * @author Kevin Bourrillion
43   * @since 1.0
44   */
45  @GwtCompatible(emulated = true)
46  public final class Shorts {
47    private Shorts() {}
48  
49    /**
50     * The number of bytes required to represent a primitive {@code short} value.
51     *
52     * <p><b>Java 8 users:</b> use {@link Short#BYTES} instead.
53     */
54    public static final int BYTES = Short.SIZE / Byte.SIZE;
55  
56    /**
57     * The largest power of two that can be represented as a {@code short}.
58     *
59     * @since 10.0
60     */
61    public static final short MAX_POWER_OF_TWO = 1 << (Short.SIZE - 2);
62  
63    /**
64     * Returns a hash code for {@code value}; equal to the result of invoking
65     * {@code ((Short) value).hashCode()}.
66     *
67     * <p><b>Java 8 users:</b> use {@link Short#hashCode(short)} instead.
68     *
69     * @param value a primitive {@code short} value
70     * @return a hash code for the value
71     */
72    public static int hashCode(short value) {
73      return value;
74    }
75  
76    /**
77     * Returns the {@code short} value that is equal to {@code value}, if possible.
78     *
79     * @param value any value in the range of the {@code short} type
80     * @return the {@code short} value that equals {@code value}
81     * @throws IllegalArgumentException if {@code value} is greater than {@link Short#MAX_VALUE} or
82     *     less than {@link Short#MIN_VALUE}
83     */
84    public static short checkedCast(long value) {
85      short result = (short) value;
86      checkArgument(result == value, "Out of range: %s", value);
87      return result;
88    }
89  
90    /**
91     * Returns the {@code short} nearest in value to {@code value}.
92     *
93     * @param value any {@code long} value
94     * @return the same value cast to {@code short} if it is in the range of the {@code short} type,
95     *     {@link Short#MAX_VALUE} if it is too large, or {@link Short#MIN_VALUE} if it is too small
96     */
97    public static short saturatedCast(long value) {
98      if (value > Short.MAX_VALUE) {
99        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    * Sorts the elements of {@code array} in descending order.
459    *
460    * @since 23.1
461    */
462   public static void sortDescending(short[] array) {
463     checkNotNull(array);
464     sortDescending(array, 0, array.length);
465   }
466 
467   /**
468    * Sorts the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex}
469    * exclusive in descending order.
470    *
471    * @since 23.1
472    */
473   public static void sortDescending(short[] array, int fromIndex, int toIndex) {
474     checkNotNull(array);
475     checkPositionIndexes(fromIndex, toIndex, array.length);
476     Arrays.sort(array, fromIndex, toIndex);
477     reverse(array, fromIndex, toIndex);
478   }
479 
480   /**
481    * Reverses the elements of {@code array}. This is equivalent to {@code
482    * Collections.reverse(Shorts.asList(array))}, but is likely to be more efficient.
483    *
484    * @since 23.1
485    */
486   public static void reverse(short[] array) {
487     checkNotNull(array);
488     reverse(array, 0, array.length);
489   }
490 
491   /**
492    * Reverses the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex}
493    * exclusive. This is equivalent to {@code
494    * Collections.reverse(Shorts.asList(array).subList(fromIndex, toIndex))}, but is likely to be
495    * more efficient.
496    *
497    * @throws IndexOutOfBoundsException if {@code fromIndex < 0}, {@code toIndex > array.length}, or
498    *     {@code toIndex > fromIndex}
499    * @since 23.1
500    */
501   public static void reverse(short[] array, int fromIndex, int toIndex) {
502     checkNotNull(array);
503     checkPositionIndexes(fromIndex, toIndex, array.length);
504     for (int i = fromIndex, j = toIndex - 1; i < j; i++, j--) {
505       short tmp = array[i];
506       array[i] = array[j];
507       array[j] = tmp;
508     }
509   }
510 
511   /**
512    * Returns an array containing each value of {@code collection}, converted to a {@code short}
513    * value in the manner of {@link Number#shortValue}.
514    *
515    * <p>Elements are copied from the argument collection as if by {@code
516    * collection.toArray()}. Calling this method is as thread-safe as calling that method.
517    *
518    * @param collection a collection of {@code Number} instances
519    * @return an array containing the same values as {@code collection}, in the same order, converted
520    *     to primitives
521    * @throws NullPointerException if {@code collection} or any of its elements is null
522    * @since 1.0 (parameter was {@code Collection<Short>} before 12.0)
523    */
524   public static short[] toArray(Collection<? extends Number> collection) {
525     if (collection instanceof ShortArrayAsList) {
526       return ((ShortArrayAsList) collection).toShortArray();
527     }
528 
529     Object[] boxedArray = collection.toArray();
530     int len = boxedArray.length;
531     short[] array = new short[len];
532     for (int i = 0; i < len; i++) {
533       // checkNotNull for GWT (do not optimize)
534       array[i] = ((Number) checkNotNull(boxedArray[i])).shortValue();
535     }
536     return array;
537   }
538 
539   /**
540    * Returns a fixed-size list backed by the specified array, similar to
541    * {@link Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)}, but any
542    * attempt to set a value to {@code null} will result in a {@link NullPointerException}.
543    *
544    * <p>The returned list maintains the values, but not the identities, of {@code Short} objects
545    * written to or read from it. For example, whether {@code list.get(0) == list.get(0)} is true for
546    * the returned list is unspecified.
547    *
548    * @param backingArray the array to back the list
549    * @return a list view of the array
550    */
551   public static List<Short> asList(short... backingArray) {
552     if (backingArray.length == 0) {
553       return Collections.emptyList();
554     }
555     return new ShortArrayAsList(backingArray);
556   }
557 
558   @GwtCompatible
559   private static class ShortArrayAsList extends AbstractList<Short>
560       implements RandomAccess, Serializable {
561     final short[] array;
562     final int start;
563     final int end;
564 
565     ShortArrayAsList(short[] array) {
566       this(array, 0, array.length);
567     }
568 
569     ShortArrayAsList(short[] array, int start, int end) {
570       this.array = array;
571       this.start = start;
572       this.end = end;
573     }
574 
575     @Override
576     public int size() {
577       return end - start;
578     }
579 
580     @Override
581     public boolean isEmpty() {
582       return false;
583     }
584 
585     @Override
586     public Short get(int index) {
587       checkElementIndex(index, size());
588       return array[start + index];
589     }
590 
591     @Override
592     public boolean contains(Object target) {
593       // Overridden to prevent a ton of boxing
594       return (target instanceof Short) && Shorts.indexOf(array, (Short) target, start, end) != -1;
595     }
596 
597     @Override
598     public int indexOf(Object target) {
599       // Overridden to prevent a ton of boxing
600       if (target instanceof Short) {
601         int i = Shorts.indexOf(array, (Short) target, start, end);
602         if (i >= 0) {
603           return i - start;
604         }
605       }
606       return -1;
607     }
608 
609     @Override
610     public int lastIndexOf(Object target) {
611       // Overridden to prevent a ton of boxing
612       if (target instanceof Short) {
613         int i = Shorts.lastIndexOf(array, (Short) target, start, end);
614         if (i >= 0) {
615           return i - start;
616         }
617       }
618       return -1;
619     }
620 
621     @Override
622     public Short set(int index, Short element) {
623       checkElementIndex(index, size());
624       short oldValue = array[start + index];
625       // checkNotNull for GWT (do not optimize)
626       array[start + index] = checkNotNull(element);
627       return oldValue;
628     }
629 
630     @Override
631     public List<Short> subList(int fromIndex, int toIndex) {
632       int size = size();
633       checkPositionIndexes(fromIndex, toIndex, size);
634       if (fromIndex == toIndex) {
635         return Collections.emptyList();
636       }
637       return new ShortArrayAsList(array, start + fromIndex, start + toIndex);
638     }
639 
640     @Override
641     public boolean equals(Object object) {
642       if (object == this) {
643         return true;
644       }
645       if (object instanceof ShortArrayAsList) {
646         ShortArrayAsList that = (ShortArrayAsList) object;
647         int size = size();
648         if (that.size() != size) {
649           return false;
650         }
651         for (int i = 0; i < size; i++) {
652           if (array[start + i] != that.array[that.start + i]) {
653             return false;
654           }
655         }
656         return true;
657       }
658       return super.equals(object);
659     }
660 
661     @Override
662     public int hashCode() {
663       int result = 1;
664       for (int i = start; i < end; i++) {
665         result = 31 * result + Shorts.hashCode(array[i]);
666       }
667       return result;
668     }
669 
670     @Override
671     public String toString() {
672       StringBuilder builder = new StringBuilder(size() * 6);
673       builder.append('[').append(array[start]);
674       for (int i = start + 1; i < end; i++) {
675         builder.append(", ").append(array[i]);
676       }
677       return builder.append(']').toString();
678     }
679 
680     short[] toShortArray() {
681       return Arrays.copyOfRange(array, start, end);
682     }
683 
684     private static final long serialVersionUID = 0;
685   }
686 }