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.Beta;
025    import com.google.common.annotations.GwtCompatible;
026    import com.google.common.annotations.GwtIncompatible;
027    
028    import java.io.Serializable;
029    import java.util.AbstractList;
030    import java.util.Arrays;
031    import java.util.Collection;
032    import java.util.Collections;
033    import java.util.Comparator;
034    import java.util.List;
035    import java.util.RandomAccess;
036    
037    import javax.annotation.CheckForNull;
038    
039    /**
040     * Static utility methods pertaining to {@code int} primitives, that are not
041     * already found in either {@link Integer} or {@link Arrays}.
042     *
043     * <p>See the Guava User Guide article on <a href=
044     * "http://code.google.com/p/guava-libraries/wiki/PrimitivesExplained">
045     * primitive utilities</a>.
046     *
047     * @author Kevin Bourrillion
048     * @since 1.0
049     */
050    @GwtCompatible(emulated = true)
051    public final class Ints {
052      private Ints() {}
053    
054      /**
055       * The number of bytes required to represent a primitive {@code int}
056       * value.
057       */
058      public static final int BYTES = Integer.SIZE / Byte.SIZE;
059    
060      /**
061       * The largest power of two that can be represented as an {@code int}.
062       *
063       * @since 10.0
064       */
065      public static final int MAX_POWER_OF_TWO = 1 << (Integer.SIZE - 2);
066    
067      /**
068       * Returns a hash code for {@code value}; equal to the result of invoking
069       * {@code ((Integer) value).hashCode()}.
070       *
071       * @param value a primitive {@code int} value
072       * @return a hash code for the value
073       */
074      public static int hashCode(int value) {
075        return value;
076      }
077    
078      /**
079       * Returns the {@code int} value that is equal to {@code value}, if possible.
080       *
081       * @param value any value in the range of the {@code int} type
082       * @return the {@code int} value that equals {@code value}
083       * @throws IllegalArgumentException if {@code value} is greater than {@link
084       *     Integer#MAX_VALUE} or less than {@link Integer#MIN_VALUE}
085       */
086      public static int checkedCast(long value) {
087        int result = (int) value;
088        checkArgument(result == value, "Out of range: %s", value);
089        return result;
090      }
091    
092      /**
093       * Returns the {@code int} nearest in value to {@code value}.
094       *
095       * @param value any {@code long} value
096       * @return the same value cast to {@code int} if it is in the range of the
097       *     {@code int} type, {@link Integer#MAX_VALUE} if it is too large,
098       *     or {@link Integer#MIN_VALUE} if it is too small
099       */
100      public static int saturatedCast(long value) {
101        if (value > Integer.MAX_VALUE) {
102          return Integer.MAX_VALUE;
103        }
104        if (value < Integer.MIN_VALUE) {
105          return Integer.MIN_VALUE;
106        }
107        return (int) value;
108      }
109    
110      /**
111       * Compares the two specified {@code int} values. The sign of the value
112       * returned is the same as that of {@code ((Integer) a).compareTo(b)}.
113       *
114       * @param a the first {@code int} to compare
115       * @param b the second {@code int} to compare
116       * @return a negative value if {@code a} is less than {@code b}; a positive
117       *     value if {@code a} is greater than {@code b}; or zero if they are equal
118       */
119      public static int compare(int a, int b) {
120        return (a < b) ? -1 : ((a > b) ? 1 : 0);
121      }
122    
123      /**
124       * Returns {@code true} if {@code target} is present as an element anywhere in
125       * {@code array}.
126       *
127       * @param array an array of {@code int} values, possibly empty
128       * @param target a primitive {@code int} value
129       * @return {@code true} if {@code array[i] == target} for some value of {@code
130       *     i}
131       */
132      public static boolean contains(int[] array, int target) {
133        for (int value : array) {
134          if (value == target) {
135            return true;
136          }
137        }
138        return false;
139      }
140    
141      /**
142       * Returns the index of the first appearance of the value {@code target} in
143       * {@code array}.
144       *
145       * @param array an array of {@code int} values, possibly empty
146       * @param target a primitive {@code int} value
147       * @return the least index {@code i} for which {@code array[i] == target}, or
148       *     {@code -1} if no such index exists.
149       */
150      public static int indexOf(int[] array, int target) {
151        return indexOf(array, target, 0, array.length);
152      }
153    
154      // TODO(kevinb): consider making this public
155      private static int indexOf(
156          int[] array, int target, int start, int end) {
157        for (int i = start; i < end; i++) {
158          if (array[i] == target) {
159            return i;
160          }
161        }
162        return -1;
163      }
164    
165      /**
166       * Returns the start position of the first occurrence of the specified {@code
167       * target} within {@code array}, or {@code -1} if there is no such occurrence.
168       *
169       * <p>More formally, returns the lowest index {@code i} such that {@code
170       * java.util.Arrays.copyOfRange(array, i, i + target.length)} contains exactly
171       * the same elements as {@code target}.
172       *
173       * @param array the array to search for the sequence {@code target}
174       * @param target the array to search for as a sub-sequence of {@code array}
175       */
176      public static int indexOf(int[] array, int[] target) {
177        checkNotNull(array, "array");
178        checkNotNull(target, "target");
179        if (target.length == 0) {
180          return 0;
181        }
182    
183        outer:
184        for (int i = 0; i < array.length - target.length + 1; i++) {
185          for (int j = 0; j < target.length; j++) {
186            if (array[i + j] != target[j]) {
187              continue outer;
188            }
189          }
190          return i;
191        }
192        return -1;
193      }
194    
195      /**
196       * Returns the index of the last appearance of the value {@code target} in
197       * {@code array}.
198       *
199       * @param array an array of {@code int} values, possibly empty
200       * @param target a primitive {@code int} value
201       * @return the greatest index {@code i} for which {@code array[i] == target},
202       *     or {@code -1} if no such index exists.
203       */
204      public static int lastIndexOf(int[] array, int target) {
205        return lastIndexOf(array, target, 0, array.length);
206      }
207    
208      // TODO(kevinb): consider making this public
209      private static int lastIndexOf(
210          int[] array, int target, int start, int end) {
211        for (int i = end - 1; i >= start; i--) {
212          if (array[i] == target) {
213            return i;
214          }
215        }
216        return -1;
217      }
218    
219      /**
220       * Returns the least value present in {@code array}.
221       *
222       * @param array a <i>nonempty</i> array of {@code int} values
223       * @return the value present in {@code array} that is less than or equal to
224       *     every other value in the array
225       * @throws IllegalArgumentException if {@code array} is empty
226       */
227      public static int min(int... array) {
228        checkArgument(array.length > 0);
229        int min = array[0];
230        for (int i = 1; i < array.length; i++) {
231          if (array[i] < min) {
232            min = array[i];
233          }
234        }
235        return min;
236      }
237    
238      /**
239       * Returns the greatest value present in {@code array}.
240       *
241       * @param array a <i>nonempty</i> array of {@code int} values
242       * @return the value present in {@code array} that is greater than or equal to
243       *     every other value in the array
244       * @throws IllegalArgumentException if {@code array} is empty
245       */
246      public static int max(int... array) {
247        checkArgument(array.length > 0);
248        int max = array[0];
249        for (int i = 1; i < array.length; i++) {
250          if (array[i] > max) {
251            max = array[i];
252          }
253        }
254        return max;
255      }
256    
257      /**
258       * Returns the values from each provided array combined into a single array.
259       * For example, {@code concat(new int[] {a, b}, new int[] {}, new
260       * int[] {c}} returns the array {@code {a, b, c}}.
261       *
262       * @param arrays zero or more {@code int} arrays
263       * @return a single array containing all the values from the source arrays, in
264       *     order
265       */
266      public static int[] concat(int[]... arrays) {
267        int length = 0;
268        for (int[] array : arrays) {
269          length += array.length;
270        }
271        int[] result = new int[length];
272        int pos = 0;
273        for (int[] array : arrays) {
274          System.arraycopy(array, 0, result, pos, array.length);
275          pos += array.length;
276        }
277        return result;
278      }
279    
280      /**
281       * Returns a big-endian representation of {@code value} in a 4-element byte
282       * array; equivalent to {@code ByteBuffer.allocate(4).putInt(value).array()}.
283       * For example, the input value {@code 0x12131415} would yield the byte array
284       * {@code {0x12, 0x13, 0x14, 0x15}}.
285       *
286       * <p>If you need to convert and concatenate several values (possibly even of
287       * different types), use a shared {@link java.nio.ByteBuffer} instance, or use
288       * {@link com.google.common.io.ByteStreams#newDataOutput()} to get a growable
289       * buffer.
290       */
291      @GwtIncompatible("doesn't work")
292      public static byte[] toByteArray(int value) {
293        return new byte[] {
294            (byte) (value >> 24),
295            (byte) (value >> 16),
296            (byte) (value >> 8),
297            (byte) value};
298      }
299    
300      /**
301       * Returns the {@code int} value whose big-endian representation is stored in
302       * the first 4 bytes of {@code bytes}; equivalent to {@code
303       * ByteBuffer.wrap(bytes).getInt()}. For example, the input byte array {@code
304       * {0x12, 0x13, 0x14, 0x15, 0x33}} would yield the {@code int} value {@code
305       * 0x12131415}.
306       *
307       * <p>Arguably, it's preferable to use {@link java.nio.ByteBuffer}; that
308       * library exposes much more flexibility at little cost in readability.
309       *
310       * @throws IllegalArgumentException if {@code bytes} has fewer than 4 elements
311       */
312      @GwtIncompatible("doesn't work")
313      public static int fromByteArray(byte[] bytes) {
314        checkArgument(bytes.length >= BYTES,
315            "array too small: %s < %s", bytes.length, BYTES);
316        return fromBytes(bytes[0], bytes[1], bytes[2], bytes[3]);
317      }
318    
319      /**
320       * Returns the {@code int} value whose byte representation is the given 4
321       * bytes, in big-endian order; equivalent to {@code Ints.fromByteArray(new
322       * byte[] {b1, b2, b3, b4})}.
323       *
324       * @since 7.0
325       */
326      @GwtIncompatible("doesn't work")
327      public static int fromBytes(byte b1, byte b2, byte b3, byte b4) {
328        return b1 << 24 | (b2 & 0xFF) << 16 | (b3 & 0xFF) << 8 | (b4 & 0xFF);
329      }
330    
331      /**
332       * Returns an array containing the same values as {@code array}, but
333       * guaranteed to be of a specified minimum length. If {@code array} already
334       * has a length of at least {@code minLength}, it is returned directly.
335       * Otherwise, a new array of size {@code minLength + padding} is returned,
336       * containing the values of {@code array}, and zeroes in the remaining places.
337       *
338       * @param array the source array
339       * @param minLength the minimum length the returned array must guarantee
340       * @param padding an extra amount to "grow" the array by if growth is
341       *     necessary
342       * @throws IllegalArgumentException if {@code minLength} or {@code padding} is
343       *     negative
344       * @return an array containing the values of {@code array}, with guaranteed
345       *     minimum length {@code minLength}
346       */
347      public static int[] ensureCapacity(
348          int[] array, int minLength, int padding) {
349        checkArgument(minLength >= 0, "Invalid minLength: %s", minLength);
350        checkArgument(padding >= 0, "Invalid padding: %s", padding);
351        return (array.length < minLength)
352            ? copyOf(array, minLength + padding)
353            : array;
354      }
355    
356      // Arrays.copyOf() requires Java 6
357      private static int[] copyOf(int[] original, int length) {
358        int[] copy = new int[length];
359        System.arraycopy(original, 0, copy, 0, Math.min(original.length, length));
360        return copy;
361      }
362    
363      /**
364       * Returns a string containing the supplied {@code int} values separated
365       * by {@code separator}. For example, {@code join("-", 1, 2, 3)} returns
366       * the string {@code "1-2-3"}.
367       *
368       * @param separator the text that should appear between consecutive values in
369       *     the resulting string (but not at the start or end)
370       * @param array an array of {@code int} values, possibly empty
371       */
372      public static String join(String separator, int... array) {
373        checkNotNull(separator);
374        if (array.length == 0) {
375          return "";
376        }
377    
378        // For pre-sizing a builder, just get the right order of magnitude
379        StringBuilder builder = new StringBuilder(array.length * 5);
380        builder.append(array[0]);
381        for (int i = 1; i < array.length; i++) {
382          builder.append(separator).append(array[i]);
383        }
384        return builder.toString();
385      }
386    
387      /**
388       * Returns a comparator that compares two {@code int} arrays
389       * lexicographically. That is, it compares, using {@link
390       * #compare(int, int)}), the first pair of values that follow any
391       * common prefix, or when one array is a prefix of the other, treats the
392       * shorter array as the lesser. For example, {@code [] < [1] < [1, 2] < [2]}.
393       *
394       * <p>The returned comparator is inconsistent with {@link
395       * Object#equals(Object)} (since arrays support only identity equality), but
396       * it is consistent with {@link Arrays#equals(int[], int[])}.
397       *
398       * @see <a href="http://en.wikipedia.org/wiki/Lexicographical_order">
399       *     Lexicographical order article at Wikipedia</a>
400       * @since 2.0
401       */
402      public static Comparator<int[]> lexicographicalComparator() {
403        return LexicographicalComparator.INSTANCE;
404      }
405    
406      private enum LexicographicalComparator implements Comparator<int[]> {
407        INSTANCE;
408    
409        @Override
410        public int compare(int[] left, int[] right) {
411          int minLength = Math.min(left.length, right.length);
412          for (int i = 0; i < minLength; i++) {
413            int result = Ints.compare(left[i], right[i]);
414            if (result != 0) {
415              return result;
416            }
417          }
418          return left.length - right.length;
419        }
420      }
421    
422      /**
423       * Returns an array containing each value of {@code collection}, converted to
424       * a {@code int} value in the manner of {@link Number#intValue}.
425       *
426       * <p>Elements are copied from the argument collection as if by {@code
427       * collection.toArray()}.  Calling this method is as thread-safe as calling
428       * that method.
429       *
430       * @param collection a collection of {@code Number} instances
431       * @return an array containing the same values as {@code collection}, in the
432       *     same order, converted to primitives
433       * @throws NullPointerException if {@code collection} or any of its elements
434       *     is null
435       * @since 1.0 (parameter was {@code Collection<Integer>} before 12.0)
436       */
437      public static int[] toArray(Collection<? extends Number> collection) {
438        if (collection instanceof IntArrayAsList) {
439          return ((IntArrayAsList) collection).toIntArray();
440        }
441    
442        Object[] boxedArray = collection.toArray();
443        int len = boxedArray.length;
444        int[] array = new int[len];
445        for (int i = 0; i < len; i++) {
446          // checkNotNull for GWT (do not optimize)
447          array[i] = ((Number) checkNotNull(boxedArray[i])).intValue();
448        }
449        return array;
450      }
451    
452      /**
453       * Returns a fixed-size list backed by the specified array, similar to {@link
454       * Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)},
455       * but any attempt to set a value to {@code null} will result in a {@link
456       * NullPointerException}.
457       *
458       * <p>The returned list maintains the values, but not the identities, of
459       * {@code Integer} objects written to or read from it.  For example, whether
460       * {@code list.get(0) == list.get(0)} is true for the returned list is
461       * unspecified.
462       *
463       * @param backingArray the array to back the list
464       * @return a list view of the array
465       */
466      public static List<Integer> asList(int... backingArray) {
467        if (backingArray.length == 0) {
468          return Collections.emptyList();
469        }
470        return new IntArrayAsList(backingArray);
471      }
472    
473      @GwtCompatible
474      private static class IntArrayAsList extends AbstractList<Integer>
475          implements RandomAccess, Serializable {
476        final int[] array;
477        final int start;
478        final int end;
479    
480        IntArrayAsList(int[] array) {
481          this(array, 0, array.length);
482        }
483    
484        IntArrayAsList(int[] array, int start, int end) {
485          this.array = array;
486          this.start = start;
487          this.end = end;
488        }
489    
490        @Override public int size() {
491          return end - start;
492        }
493    
494        @Override public boolean isEmpty() {
495          return false;
496        }
497    
498        @Override public Integer get(int index) {
499          checkElementIndex(index, size());
500          return array[start + index];
501        }
502    
503        @Override public boolean contains(Object target) {
504          // Overridden to prevent a ton of boxing
505          return (target instanceof Integer)
506              && Ints.indexOf(array, (Integer) target, start, end) != -1;
507        }
508    
509        @Override public int indexOf(Object target) {
510          // Overridden to prevent a ton of boxing
511          if (target instanceof Integer) {
512            int i = Ints.indexOf(array, (Integer) target, start, end);
513            if (i >= 0) {
514              return i - start;
515            }
516          }
517          return -1;
518        }
519    
520        @Override public int lastIndexOf(Object target) {
521          // Overridden to prevent a ton of boxing
522          if (target instanceof Integer) {
523            int i = Ints.lastIndexOf(array, (Integer) target, start, end);
524            if (i >= 0) {
525              return i - start;
526            }
527          }
528          return -1;
529        }
530    
531        @Override public Integer set(int index, Integer element) {
532          checkElementIndex(index, size());
533          int oldValue = array[start + index];
534          // checkNotNull for GWT (do not optimize)
535          array[start + index] = checkNotNull(element);
536          return oldValue;
537        }
538    
539        @Override public List<Integer> subList(int fromIndex, int toIndex) {
540          int size = size();
541          checkPositionIndexes(fromIndex, toIndex, size);
542          if (fromIndex == toIndex) {
543            return Collections.emptyList();
544          }
545          return new IntArrayAsList(array, start + fromIndex, start + toIndex);
546        }
547    
548        @Override public boolean equals(Object object) {
549          if (object == this) {
550            return true;
551          }
552          if (object instanceof IntArrayAsList) {
553            IntArrayAsList that = (IntArrayAsList) object;
554            int size = size();
555            if (that.size() != size) {
556              return false;
557            }
558            for (int i = 0; i < size; i++) {
559              if (array[start + i] != that.array[that.start + i]) {
560                return false;
561              }
562            }
563            return true;
564          }
565          return super.equals(object);
566        }
567    
568        @Override public int hashCode() {
569          int result = 1;
570          for (int i = start; i < end; i++) {
571            result = 31 * result + Ints.hashCode(array[i]);
572          }
573          return result;
574        }
575    
576        @Override public String toString() {
577          StringBuilder builder = new StringBuilder(size() * 5);
578          builder.append('[').append(array[start]);
579          for (int i = start + 1; i < end; i++) {
580            builder.append(", ").append(array[i]);
581          }
582          return builder.append(']').toString();
583        }
584    
585        int[] toIntArray() {
586          // Arrays.copyOfRange() is not available under GWT
587          int size = size();
588          int[] result = new int[size];
589          System.arraycopy(array, start, result, 0, size);
590          return result;
591        }
592    
593        private static final long serialVersionUID = 0;
594      }
595    
596      /**
597       * Parses the specified string as a signed decimal integer value. The ASCII
598       * character {@code '-'} (<code>'&#92;u002D'</code>) is recognized as the
599       * minus sign.
600       *
601       * <p>Unlike {@link Integer#parseInt(String)}, this method returns
602       * {@code null} instead of throwing an exception if parsing fails.
603       *
604       * <p>Note that strings prefixed with ASCII {@code '+'} are rejected, even
605       * under JDK 7, despite the change to {@link Integer#parseInt(String)} for
606       * that version.
607       *
608       * @param string the string representation of an integer value
609       * @return the integer value represented by {@code string}, or {@code null} if
610       *     {@code string} has a length of zero or cannot be parsed as an integer
611       *     value
612       * @since 11.0
613       */
614      @Beta
615      @CheckForNull
616      @GwtIncompatible("TODO")
617      public static Integer tryParse(String string) {
618        return AndroidInteger.tryParse(string, 10);
619      }
620    }