1/*
2 * Copyright (C) 2008 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.common.primitives;
18
19import static com.google.common.base.Preconditions.checkArgument;
20import static com.google.common.base.Preconditions.checkElementIndex;
21import static com.google.common.base.Preconditions.checkNotNull;
22import static com.google.common.base.Preconditions.checkPositionIndexes;
23
24import com.google.common.annotations.Beta;
25import com.google.common.annotations.GwtCompatible;
26import com.google.common.annotations.GwtIncompatible;
27import com.google.common.base.Converter;
28
29import java.io.Serializable;
30import java.util.AbstractList;
31import java.util.Arrays;
32import java.util.Collection;
33import java.util.Collections;
34import java.util.Comparator;
35import java.util.List;
36import java.util.RandomAccess;
37
38/**
39 * Static utility methods pertaining to {@code short} primitives, that are not
40 * already found in either {@link Short} or {@link Arrays}.
41 *
42 * <p>See the Guava User Guide article on <a href=
43 * "http://code.google.com/p/guava-libraries/wiki/PrimitivesExplained">
44 * primitive utilities</a>.
45 *
46 * @author Kevin Bourrillion
47 * @since 1.0
48 */
49@GwtCompatible(emulated = true)
50public final class Shorts {
51  private Shorts() {}
52
53  /**
54   * The number of bytes required to represent a primitive {@code short}
55   * value.
56   */
57  public static final int BYTES = Short.SIZE / Byte.SIZE;
58
59  /**
60   * The largest power of two that can be represented as a {@code short}.
61   *
62   * @since 10.0
63   */
64  public static final short MAX_POWER_OF_TWO = 1 << (Short.SIZE - 2);
65
66  /**
67   * Returns a hash code for {@code value}; equal to the result of invoking
68   * {@code ((Short) value).hashCode()}.
69   *
70   * @param value a primitive {@code short} value
71   * @return a hash code for the value
72   */
73  public static int hashCode(short value) {
74    return value;
75  }
76
77  /**
78   * Returns the {@code short} value that is equal to {@code value}, if
79   * 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
84   *     Short#MAX_VALUE} or less than {@link Short#MIN_VALUE}
85   */
86  public static short checkedCast(long value) {
87    short result = (short) value;
88    if (result != value) {
89      // don't use checkArgument here, to avoid boxing
90      throw new IllegalArgumentException("Out of range: " + value);
91    }
92    return result;
93  }
94
95  /**
96   * Returns the {@code short} nearest in value to {@code value}.
97   *
98   * @param value any {@code long} value
99   * @return the same value cast to {@code short} if it is in the range of the
100   *     {@code short} type, {@link Short#MAX_VALUE} if it is too large,
101   *     or {@link Short#MIN_VALUE} if it is too small
102   */
103  public static short saturatedCast(long value) {
104    if (value > Short.MAX_VALUE) {
105      return Short.MAX_VALUE;
106    }
107    if (value < Short.MIN_VALUE) {
108      return Short.MIN_VALUE;
109    }
110    return (short) value;
111  }
112
113  /**
114   * Compares the two specified {@code short} values. The sign of the value
115   * returned is the same as that of {@code ((Short) a).compareTo(b)}.
116   *
117   * <p><b>Note for Java 7 and later:</b> this method should be treated as
118   * deprecated; use the equivalent {@link Short#compare} method instead.
119   *
120   * @param a the first {@code short} to compare
121   * @param b the second {@code short} to compare
122   * @return a negative value if {@code a} is less than {@code b}; a positive
123   *     value if {@code a} is greater than {@code b}; or zero if they are equal
124   */
125  public static int compare(short a, short b) {
126    return a - b; // safe due to restricted range
127  }
128
129  /**
130   * Returns {@code true} if {@code target} is present as an element anywhere in
131   * {@code array}.
132   *
133   * @param array an array of {@code short} values, possibly empty
134   * @param target a primitive {@code short} value
135   * @return {@code true} if {@code array[i] == target} for some value of {@code
136   *     i}
137   */
138  public static boolean contains(short[] array, short target) {
139    for (short value : array) {
140      if (value == target) {
141        return true;
142      }
143    }
144    return false;
145  }
146
147  /**
148   * Returns the index of the first appearance of the value {@code target} in
149   * {@code array}.
150   *
151   * @param array an array of {@code short} values, possibly empty
152   * @param target a primitive {@code short} value
153   * @return the least index {@code i} for which {@code array[i] == target}, or
154   *     {@code -1} if no such index exists.
155   */
156  public static int indexOf(short[] array, short target) {
157    return indexOf(array, target, 0, array.length);
158  }
159
160  // TODO(kevinb): consider making this public
161  private static int indexOf(
162      short[] array, short target, int start, int end) {
163    for (int i = start; i < end; i++) {
164      if (array[i] == target) {
165        return i;
166      }
167    }
168    return -1;
169  }
170
171  /**
172   * Returns the start position of the first occurrence of the specified {@code
173   * target} within {@code array}, or {@code -1} if there is no such occurrence.
174   *
175   * <p>More formally, returns the lowest index {@code i} such that {@code
176   * java.util.Arrays.copyOfRange(array, i, i + target.length)} contains exactly
177   * the same elements as {@code target}.
178   *
179   * @param array the array to search for the sequence {@code target}
180   * @param target the array to search for as a sub-sequence of {@code array}
181   */
182  public static int indexOf(short[] array, short[] target) {
183    checkNotNull(array, "array");
184    checkNotNull(target, "target");
185    if (target.length == 0) {
186      return 0;
187    }
188
189    outer:
190    for (int i = 0; i < array.length - target.length + 1; i++) {
191      for (int j = 0; j < target.length; j++) {
192        if (array[i + j] != target[j]) {
193          continue outer;
194        }
195      }
196      return i;
197    }
198    return -1;
199  }
200
201  /**
202   * Returns the index of the last appearance of the value {@code target} in
203   * {@code array}.
204   *
205   * @param array an array of {@code short} values, possibly empty
206   * @param target a primitive {@code short} value
207   * @return the greatest index {@code i} for which {@code array[i] == target},
208   *     or {@code -1} if no such index exists.
209   */
210  public static int lastIndexOf(short[] array, short target) {
211    return lastIndexOf(array, target, 0, array.length);
212  }
213
214  // TODO(kevinb): consider making this public
215  private static int lastIndexOf(
216      short[] array, short target, int start, int end) {
217    for (int i = end - 1; i >= start; i--) {
218      if (array[i] == target) {
219        return i;
220      }
221    }
222    return -1;
223  }
224
225  /**
226   * Returns the least value present in {@code array}.
227   *
228   * @param array a <i>nonempty</i> array of {@code short} values
229   * @return the value present in {@code array} that is less than or equal to
230   *     every other value in the array
231   * @throws IllegalArgumentException if {@code array} is empty
232   */
233  public static short min(short... array) {
234    checkArgument(array.length > 0);
235    short min = array[0];
236    for (int i = 1; i < array.length; i++) {
237      if (array[i] < min) {
238        min = array[i];
239      }
240    }
241    return min;
242  }
243
244  /**
245   * Returns the greatest value present in {@code array}.
246   *
247   * @param array a <i>nonempty</i> array of {@code short} values
248   * @return the value present in {@code array} that is greater than or equal to
249   *     every other value in the array
250   * @throws IllegalArgumentException if {@code array} is empty
251   */
252  public static short max(short... array) {
253    checkArgument(array.length > 0);
254    short max = array[0];
255    for (int i = 1; i < array.length; i++) {
256      if (array[i] > max) {
257        max = array[i];
258      }
259    }
260    return max;
261  }
262
263  /**
264   * Returns the values from each provided array combined into a single array.
265   * For example, {@code concat(new short[] {a, b}, new short[] {}, new
266   * short[] {c}} returns the array {@code {a, b, c}}.
267   *
268   * @param arrays zero or more {@code short} arrays
269   * @return a single array containing all the values from the source arrays, in
270   *     order
271   */
272  public static short[] concat(short[]... arrays) {
273    int length = 0;
274    for (short[] array : arrays) {
275      length += array.length;
276    }
277    short[] result = new short[length];
278    int pos = 0;
279    for (short[] array : arrays) {
280      System.arraycopy(array, 0, result, pos, array.length);
281      pos += array.length;
282    }
283    return result;
284  }
285
286  /**
287   * Returns a big-endian representation of {@code value} in a 2-element byte
288   * array; equivalent to {@code
289   * ByteBuffer.allocate(2).putShort(value).array()}.  For example, the input
290   * value {@code (short) 0x1234} would yield the byte array {@code {0x12,
291   * 0x34}}.
292   *
293   * <p>If you need to convert and concatenate several values (possibly even of
294   * different types), use a shared {@link java.nio.ByteBuffer} instance, or use
295   * {@link com.google.common.io.ByteStreams#newDataOutput()} to get a growable
296   * buffer.
297   */
298  @GwtIncompatible("doesn't work")
299  public static byte[] toByteArray(short value) {
300    return new byte[] {
301        (byte) (value >> 8),
302        (byte) value};
303  }
304
305  /**
306   * Returns the {@code short} value whose big-endian representation is
307   * stored in the first 2 bytes of {@code bytes}; equivalent to {@code
308   * ByteBuffer.wrap(bytes).getShort()}. For example, the input byte array
309   * {@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
312   * library exposes much more flexibility at little cost in readability.
313   *
314   * @throws IllegalArgumentException if {@code bytes} has fewer than 2
315   *     elements
316   */
317  @GwtIncompatible("doesn't work")
318  public static short fromByteArray(byte[] bytes) {
319    checkArgument(bytes.length >= BYTES,
320        "array too small: %s < %s", bytes.length, BYTES);
321    return fromBytes(bytes[0], bytes[1]);
322  }
323
324  /**
325   * Returns the {@code short} value whose byte representation is the given 2
326   * bytes, in big-endian order; equivalent to {@code Shorts.fromByteArray(new
327   * byte[] {b1, b2})}.
328   *
329   * @since 7.0
330   */
331  @GwtIncompatible("doesn't work")
332  public static short fromBytes(byte b1, byte b2) {
333    return (short) ((b1 << 8) | (b2 & 0xFF));
334  }
335
336  private static final class ShortConverter
337      extends Converter<String, Short> implements Serializable {
338    static final ShortConverter INSTANCE = new ShortConverter();
339
340    @Override
341    protected Short doForward(String value) {
342      return Short.decode(value);
343    }
344
345    @Override
346    protected String doBackward(Short value) {
347      return value.toString();
348    }
349
350    @Override
351    public String toString() {
352      return "Shorts.stringConverter()";
353    }
354
355    private Object readResolve() {
356      return INSTANCE;
357    }
358    private static final long serialVersionUID = 1;
359  }
360
361  /**
362   * Returns a serializable converter object that converts between strings and
363   * shorts using {@link Short#decode} and {@link Short#toString()}.
364   *
365   * @since 16.0
366   */
367  @Beta
368  public static Converter<String, Short> stringConverter() {
369    return ShortConverter.INSTANCE;
370  }
371
372  /**
373   * Returns an array containing the same values as {@code array}, but
374   * guaranteed to be of a specified minimum length. If {@code array} already
375   * has a length of at least {@code minLength}, it is returned directly.
376   * Otherwise, a new array of size {@code minLength + padding} is returned,
377   * containing the values of {@code array}, and zeroes in the remaining places.
378   *
379   * @param array the source array
380   * @param minLength the minimum length the returned array must guarantee
381   * @param padding an extra amount to "grow" the array by if growth is
382   *     necessary
383   * @throws IllegalArgumentException if {@code minLength} or {@code padding} is
384   *     negative
385   * @return an array containing the values of {@code array}, with guaranteed
386   *     minimum length {@code minLength}
387   */
388  public static short[] ensureCapacity(
389      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)
393        ? copyOf(array, minLength + padding)
394        : array;
395  }
396
397  // Arrays.copyOf() requires Java 6
398  private static short[] copyOf(short[] original, int length) {
399    short[] copy = new short[length];
400    System.arraycopy(original, 0, copy, 0, Math.min(original.length, length));
401    return copy;
402  }
403
404  /**
405   * Returns a string containing the supplied {@code short} values separated
406   * by {@code separator}. For example, {@code join("-", (short) 1, (short) 2,
407   * (short) 3)} returns the string {@code "1-2-3"}.
408   *
409   * @param separator the text that should appear between consecutive values in
410   *     the resulting string (but not at the start or end)
411   * @param array an array of {@code short} values, possibly empty
412   */
413  public static String join(String separator, short... array) {
414    checkNotNull(separator);
415    if (array.length == 0) {
416      return "";
417    }
418
419    // For pre-sizing a builder, just get the right order of magnitude
420    StringBuilder builder = new StringBuilder(array.length * 6);
421    builder.append(array[0]);
422    for (int i = 1; i < array.length; i++) {
423      builder.append(separator).append(array[i]);
424    }
425    return builder.toString();
426  }
427
428  /**
429   * Returns a comparator that compares two {@code short} arrays
430   * lexicographically. That is, it compares, using {@link
431   * #compare(short, short)}), the first pair of values that follow any
432   * common prefix, or when one array is a prefix of the other, treats the
433   * shorter array as the lesser. For example, {@code [] < [(short) 1] <
434   * [(short) 1, (short) 2] < [(short) 2]}.
435   *
436   * <p>The returned comparator is inconsistent with {@link
437   * Object#equals(Object)} (since arrays support only identity equality), but
438   * it is consistent with {@link Arrays#equals(short[], short[])}.
439   *
440   * @see <a href="http://en.wikipedia.org/wiki/Lexicographical_order">
441   *     Lexicographical order article at Wikipedia</a>
442   * @since 2.0
443   */
444  public static Comparator<short[]> lexicographicalComparator() {
445    return LexicographicalComparator.INSTANCE;
446  }
447
448  private enum LexicographicalComparator implements Comparator<short[]> {
449    INSTANCE;
450
451    @Override
452    public int compare(short[] left, short[] right) {
453      int minLength = Math.min(left.length, right.length);
454      for (int i = 0; i < minLength; i++) {
455        int result = Shorts.compare(left[i], right[i]);
456        if (result != 0) {
457          return result;
458        }
459      }
460      return left.length - right.length;
461    }
462  }
463
464  /**
465   * Returns an array containing each value of {@code collection}, converted to
466   * a {@code short} value in the manner of {@link Number#shortValue}.
467   *
468   * <p>Elements are copied from the argument collection as if by {@code
469   * collection.toArray()}.  Calling this method is as thread-safe as calling
470   * that method.
471   *
472   * @param collection a collection of {@code Number} instances
473   * @return an array containing the same values as {@code collection}, in the
474   *     same order, converted to primitives
475   * @throws NullPointerException if {@code collection} or any of its elements
476   *     is null
477   * @since 1.0 (parameter was {@code Collection<Short>} before 12.0)
478   */
479  public static short[] toArray(Collection<? extends Number> collection) {
480    if (collection instanceof ShortArrayAsList) {
481      return ((ShortArrayAsList) collection).toShortArray();
482    }
483
484    Object[] boxedArray = collection.toArray();
485    int len = boxedArray.length;
486    short[] array = new short[len];
487    for (int i = 0; i < len; i++) {
488      // checkNotNull for GWT (do not optimize)
489      array[i] = ((Number) checkNotNull(boxedArray[i])).shortValue();
490    }
491    return array;
492  }
493
494  /**
495   * Returns a fixed-size list backed by the specified array, similar to {@link
496   * Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)},
497   * but any attempt to set a value to {@code null} will result in a {@link
498   * NullPointerException}.
499   *
500   * <p>The returned list maintains the values, but not the identities, of
501   * {@code Short} objects written to or read from it.  For example, whether
502   * {@code list.get(0) == list.get(0)} is true for the returned list is
503   * unspecified.
504   *
505   * @param backingArray the array to back the list
506   * @return a list view of the array
507   */
508  public static List<Short> asList(short... backingArray) {
509    if (backingArray.length == 0) {
510      return Collections.emptyList();
511    }
512    return new ShortArrayAsList(backingArray);
513  }
514
515  @GwtCompatible
516  private static class ShortArrayAsList extends AbstractList<Short>
517      implements RandomAccess, Serializable {
518    final short[] array;
519    final int start;
520    final int end;
521
522    ShortArrayAsList(short[] array) {
523      this(array, 0, array.length);
524    }
525
526    ShortArrayAsList(short[] array, int start, int end) {
527      this.array = array;
528      this.start = start;
529      this.end = end;
530    }
531
532    @Override public int size() {
533      return end - start;
534    }
535
536    @Override public boolean isEmpty() {
537      return false;
538    }
539
540    @Override public Short get(int index) {
541      checkElementIndex(index, size());
542      return array[start + index];
543    }
544
545    @Override public boolean contains(Object target) {
546      // Overridden to prevent a ton of boxing
547      return (target instanceof Short)
548          && Shorts.indexOf(array, (Short) target, start, end) != -1;
549    }
550
551    @Override public int indexOf(Object target) {
552      // Overridden to prevent a ton of boxing
553      if (target instanceof Short) {
554        int i = Shorts.indexOf(array, (Short) target, start, end);
555        if (i >= 0) {
556          return i - start;
557        }
558      }
559      return -1;
560    }
561
562    @Override public int lastIndexOf(Object target) {
563      // Overridden to prevent a ton of boxing
564      if (target instanceof Short) {
565        int i = Shorts.lastIndexOf(array, (Short) target, start, end);
566        if (i >= 0) {
567          return i - start;
568        }
569      }
570      return -1;
571    }
572
573    @Override public Short set(int index, Short element) {
574      checkElementIndex(index, size());
575      short oldValue = array[start + index];
576      // checkNotNull for GWT (do not optimize)
577      array[start + index] = checkNotNull(element);
578      return oldValue;
579    }
580
581    @Override public List<Short> subList(int fromIndex, int toIndex) {
582      int size = size();
583      checkPositionIndexes(fromIndex, toIndex, size);
584      if (fromIndex == toIndex) {
585        return Collections.emptyList();
586      }
587      return new ShortArrayAsList(array, start + fromIndex, start + toIndex);
588    }
589
590    @Override public boolean equals(Object object) {
591      if (object == this) {
592        return true;
593      }
594      if (object instanceof ShortArrayAsList) {
595        ShortArrayAsList that = (ShortArrayAsList) object;
596        int size = size();
597        if (that.size() != size) {
598          return false;
599        }
600        for (int i = 0; i < size; i++) {
601          if (array[start + i] != that.array[that.start + i]) {
602            return false;
603          }
604        }
605        return true;
606      }
607      return super.equals(object);
608    }
609
610    @Override public int hashCode() {
611      int result = 1;
612      for (int i = start; i < end; i++) {
613        result = 31 * result + Shorts.hashCode(array[i]);
614      }
615      return result;
616    }
617
618    @Override public String toString() {
619      StringBuilder builder = new StringBuilder(size() * 6);
620      builder.append('[').append(array[start]);
621      for (int i = start + 1; i < end; i++) {
622        builder.append(", ").append(array[i]);
623      }
624      return builder.append(']').toString();
625    }
626
627    short[] toShortArray() {
628      // Arrays.copyOfRange() is not available under GWT
629      int size = size();
630      short[] result = new short[size];
631      System.arraycopy(array, start, result, 0, size);
632      return result;
633    }
634
635    private static final long serialVersionUID = 0;
636  }
637}
638