1 /*
2 * Copyright (C) 2011 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.checkNotNull;
19 import static com.google.common.base.Preconditions.checkPositionIndexes;
20
21 import com.google.common.annotations.Beta;
22 import com.google.common.annotations.GwtCompatible;
23 import com.google.errorprone.annotations.CanIgnoreReturnValue;
24 import java.util.Arrays;
25 import java.util.Comparator;
26
27 /**
28 * Static utility methods pertaining to {@code int} primitives that interpret values as
29 * <i>unsigned</i> (that is, any negative value {@code x} is treated as the positive value {@code
30 * 2^32 + x}). The methods for which signedness is not an issue are in {@link Ints}, as well as
31 * signed versions of methods for which signedness is an issue.
32 *
33 * <p>In addition, this class provides several static methods for converting an {@code int} to a
34 * {@code String} and a {@code String} to an {@code int} that treat the {@code int} as an unsigned
35 * number.
36 *
37 * <p>Users of these utilities must be <i>extremely careful</i> not to mix up signed and unsigned
38 * {@code int} values. When possible, it is recommended that the {@link UnsignedInteger} wrapper
39 * class be used, at a small efficiency penalty, to enforce the distinction in the type system.
40 *
41 * <p>See the Guava User Guide article on <a
42 * href="https://github.com/google/guava/wiki/PrimitivesExplained#unsigned-support">unsigned
43 * primitive utilities</a>.
44 *
45 * @author Louis Wasserman
46 * @since 11.0
47 */
48 @Beta
49 @GwtCompatible
50 @ElementTypesAreNonnullByDefault
51 public final class UnsignedInts {
52 static final long INT_MASK = 0xffffffffL;
53
54 private UnsignedInts() {}
55
56 static int flip(int value) {
57 return value ^ Integer.MIN_VALUE;
58 }
59
60 /**
61 * Compares the two specified {@code int} values, treating them as unsigned values between {@code
62 * 0} and {@code 2^32 - 1} inclusive.
63 *
64 * <p><b>Java 8 users:</b> use {@link Integer#compareUnsigned(int, int)} instead.
65 *
66 * @param a the first unsigned {@code int} to compare
67 * @param b the second unsigned {@code int} to compare
68 * @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is
69 * greater than {@code b}; or zero if they are equal
70 */
71 public static int compare(int a, int b) {
72 return Ints.compare(flip(a), flip(b));
73 }
74
75 /**
76 * Returns the value of the given {@code int} as a {@code long}, when treated as unsigned.
77 *
78 * <p><b>Java 8 users:</b> use {@link Integer#toUnsignedLong(int)} instead.
79 */
80 public static long toLong(int value) {
81 return value & INT_MASK;
82 }
83
84 /**
85 * Returns the {@code int} value that, when treated as unsigned, is equal to {@code value}, if
86 * possible.
87 *
88 * @param value a value between 0 and 2<sup>32</sup>-1 inclusive
89 * @return the {@code int} value that, when treated as unsigned, equals {@code value}
90 * @throws IllegalArgumentException if {@code value} is negative or greater than or equal to
91 * 2<sup>32</sup>
92 * @since 21.0
93 */
94 public static int checkedCast(long value) {
95 checkArgument((value >> Integer.SIZE) == 0, "out of range: %s", value);
96 return (int) value;
97 }
98
99 /**
100 * Returns the {@code int} value that, when treated as unsigned, is nearest in value to {@code
101 * value}.
102 *
103 * @param value any {@code long} value
104 * @return {@code 2^32 - 1} if {@code value >= 2^32}, {@code 0} if {@code value <= 0}, and {@code
105 * value} cast to {@code int} otherwise
106 * @since 21.0
107 */
108 public static int saturatedCast(long value) {
109 if (value <= 0) {
110 return 0;
111 } else if (value >= (1L << 32)) {
112 return -1;
113 } else {
114 return (int) value;
115 }
116 }
117
118 /**
119 * Returns the least value present in {@code array}, treating values as unsigned.
120 *
121 * @param array a <i>nonempty</i> array of unsigned {@code int} values
122 * @return the value present in {@code array} that is less than or equal to every other value in
123 * the array according to {@link #compare}
124 * @throws IllegalArgumentException if {@code array} is empty
125 */
126 public static int min(int... array) {
127 checkArgument(array.length > 0);
128 int min = flip(array[0]);
129 for (int i = 1; i < array.length; i++) {
130 int next = flip(array[i]);
131 if (next < min) {
132 min = next;
133 }
134 }
135 return flip(min);
136 }
137
138 /**
139 * Returns the greatest value present in {@code array}, treating values as unsigned.
140 *
141 * @param array a <i>nonempty</i> array of unsigned {@code int} values
142 * @return the value present in {@code array} that is greater than or equal to every other value
143 * in the array according to {@link #compare}
144 * @throws IllegalArgumentException if {@code array} is empty
145 */
146 public static int max(int... array) {
147 checkArgument(array.length > 0);
148 int max = flip(array[0]);
149 for (int i = 1; i < array.length; i++) {
150 int next = flip(array[i]);
151 if (next > max) {
152 max = next;
153 }
154 }
155 return flip(max);
156 }
157
158 /**
159 * Returns a string containing the supplied unsigned {@code int} values separated by {@code
160 * separator}. For example, {@code join("-", 1, 2, 3)} returns the string {@code "1-2-3"}.
161 *
162 * @param separator the text that should appear between consecutive values in the resulting string
163 * (but not at the start or end)
164 * @param array an array of unsigned {@code int} values, possibly empty
165 */
166 public static String join(String separator, int... array) {
167 checkNotNull(separator);
168 if (array.length == 0) {
169 return "";
170 }
171
172 // For pre-sizing a builder, just get the right order of magnitude
173 StringBuilder builder = new StringBuilder(array.length * 5);
174 builder.append(toString(array[0]));
175 for (int i = 1; i < array.length; i++) {
176 builder.append(separator).append(toString(array[i]));
177 }
178 return builder.toString();
179 }
180
181 /**
182 * Returns a comparator that compares two arrays of unsigned {@code int} values <a
183 * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it
184 * compares, using {@link #compare(int, int)}), the first pair of values that follow any common
185 * prefix, or when one array is a prefix of the other, treats the shorter array as the lesser. For
186 * example, {@code [] < [1] < [1, 2] < [2] < [1 << 31]}.
187 *
188 * <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays
189 * support only identity equality), but it is consistent with {@link Arrays#equals(int[], int[])}.
190 */
191 public static Comparator<int[]> lexicographicalComparator() {
192 return LexicographicalComparator.INSTANCE;
193 }
194
195 enum LexicographicalComparator implements Comparator<int[]> {
196 INSTANCE;
197
198 @Override
199 public int compare(int[] left, int[] right) {
200 int minLength = Math.min(left.length, right.length);
201 for (int i = 0; i < minLength; i++) {
202 if (left[i] != right[i]) {
203 return UnsignedInts.compare(left[i], right[i]);
204 }
205 }
206 return left.length - right.length;
207 }
208
209 @Override
210 public String toString() {
211 return "UnsignedInts.lexicographicalComparator()";
212 }
213 }
214
215 /**
216 * Sorts the array, treating its elements as unsigned 32-bit integers.
217 *
218 * @since 23.1
219 */
220 public static void sort(int[] array) {
221 checkNotNull(array);
222 sort(array, 0, array.length);
223 }
224
225 /**
226 * Sorts the array between {@code fromIndex} inclusive and {@code toIndex} exclusive, treating its
227 * elements as unsigned 32-bit integers.
228 *
229 * @since 23.1
230 */
231 public static void sort(int[] array, int fromIndex, int toIndex) {
232 checkNotNull(array);
233 checkPositionIndexes(fromIndex, toIndex, array.length);
234 for (int i = fromIndex; i < toIndex; i++) {
235 array[i] = flip(array[i]);
236 }
237 Arrays.sort(array, fromIndex, toIndex);
238 for (int i = fromIndex; i < toIndex; i++) {
239 array[i] = flip(array[i]);
240 }
241 }
242
243 /**
244 * Sorts the elements of {@code array} in descending order, interpreting them as unsigned 32-bit
245 * integers.
246 *
247 * @since 23.1
248 */
249 public static void sortDescending(int[] array) {
250 checkNotNull(array);
251 sortDescending(array, 0, array.length);
252 }
253
254 /**
255 * Sorts the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex}
256 * exclusive in descending order, interpreting them as unsigned 32-bit integers.
257 *
258 * @since 23.1
259 */
260 public static void sortDescending(int[] array, int fromIndex, int toIndex) {
261 checkNotNull(array);
262 checkPositionIndexes(fromIndex, toIndex, array.length);
263 for (int i = fromIndex; i < toIndex; i++) {
264 array[i] ^= Integer.MAX_VALUE;
265 }
266 Arrays.sort(array, fromIndex, toIndex);
267 for (int i = fromIndex; i < toIndex; i++) {
268 array[i] ^= Integer.MAX_VALUE;
269 }
270 }
271
272 /**
273 * Returns dividend / divisor, where the dividend and divisor are treated as unsigned 32-bit
274 * quantities.
275 *
276 * <p><b>Java 8 users:</b> use {@link Integer#divideUnsigned(int, int)} instead.
277 *
278 * @param dividend the dividend (numerator)
279 * @param divisor the divisor (denominator)
280 * @throws ArithmeticException if divisor is 0
281 */
282 public static int divide(int dividend, int divisor) {
283 return (int) (toLong(dividend) / toLong(divisor));
284 }
285
286 /**
287 * Returns dividend % divisor, where the dividend and divisor are treated as unsigned 32-bit
288 * quantities.
289 *
290 * <p><b>Java 8 users:</b> use {@link Integer#remainderUnsigned(int, int)} instead.
291 *
292 * @param dividend the dividend (numerator)
293 * @param divisor the divisor (denominator)
294 * @throws ArithmeticException if divisor is 0
295 */
296 public static int remainder(int dividend, int divisor) {
297 return (int) (toLong(dividend) % toLong(divisor));
298 }
299
300 /**
301 * Returns the unsigned {@code int} value represented by the given string.
302 *
303 * <p>Accepts a decimal, hexadecimal, or octal number given by specifying the following prefix:
304 *
305 * <ul>
306 * <li>{@code 0x}<i>HexDigits</i>
307 * <li>{@code 0X}<i>HexDigits</i>
308 * <li>{@code #}<i>HexDigits</i>
309 * <li>{@code 0}<i>OctalDigits</i>
310 * </ul>
311 *
312 * @throws NumberFormatException if the string does not contain a valid unsigned {@code int} value
313 * @since 13.0
314 */
315 @CanIgnoreReturnValue
316 public static int decode(String stringValue) {
317 ParseRequest request = ParseRequest.fromString(stringValue);
318
319 try {
320 return parseUnsignedInt(request.rawValue, request.radix);
321 } catch (NumberFormatException e) {
322 NumberFormatException decodeException =
323 new NumberFormatException("Error parsing value: " + stringValue);
324 decodeException.initCause(e);
325 throw decodeException;
326 }
327 }
328
329 /**
330 * Returns the unsigned {@code int} value represented by the given decimal string.
331 *
332 * <p><b>Java 8 users:</b> use {@link Integer#parseUnsignedInt(String)} instead.
333 *
334 * @throws NumberFormatException if the string does not contain a valid unsigned {@code int} value
335 * @throws NullPointerException if {@code s} is null (in contrast to {@link
336 * Integer#parseInt(String)})
337 */
338 @CanIgnoreReturnValue
339 public static int parseUnsignedInt(String s) {
340 return parseUnsignedInt(s, 10);
341 }
342
343 /**
344 * Returns the unsigned {@code int} value represented by a string with the given radix.
345 *
346 * <p><b>Java 8 users:</b> use {@link Integer#parseUnsignedInt(String, int)} instead.
347 *
348 * @param string the string containing the unsigned integer representation to be parsed.
349 * @param radix the radix to use while parsing {@code s}; must be between {@link
350 * Character#MIN_RADIX} and {@link Character#MAX_RADIX}.
351 * @throws NumberFormatException if the string does not contain a valid unsigned {@code int}, or
352 * if supplied radix is invalid.
353 * @throws NullPointerException if {@code s} is null (in contrast to {@link
354 * Integer#parseInt(String)})
355 */
356 @CanIgnoreReturnValue
357 public static int parseUnsignedInt(String string, int radix) {
358 checkNotNull(string);
359 long result = Long.parseLong(string, radix);
360 if ((result & INT_MASK) != result) {
361 throw new NumberFormatException(
362 "Input " + string + " in base " + radix + " is not in the range of an unsigned integer");
363 }
364 return (int) result;
365 }
366
367 /**
368 * Returns a string representation of x, where x is treated as unsigned.
369 *
370 * <p><b>Java 8 users:</b> use {@link Integer#toUnsignedString(int)} instead.
371 */
372 public static String toString(int x) {
373 return toString(x, 10);
374 }
375
376 /**
377 * Returns a string representation of {@code x} for the given radix, where {@code x} is treated as
378 * unsigned.
379 *
380 * <p><b>Java 8 users:</b> use {@link Integer#toUnsignedString(int, int)} instead.
381 *
382 * @param x the value to convert to a string.
383 * @param radix the radix to use while working with {@code x}
384 * @throws IllegalArgumentException if {@code radix} is not between {@link Character#MIN_RADIX}
385 * and {@link Character#MAX_RADIX}.
386 */
387 public static String toString(int x, int radix) {
388 long asLong = x & INT_MASK;
389 return Long.toString(asLong, radix);
390 }
391 }