001/* 002 * Copyright (C) 2011 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.checkNotNull; 019import static com.google.common.base.Preconditions.checkPositionIndexes; 020 021import com.google.common.annotations.Beta; 022import com.google.common.annotations.GwtCompatible; 023import com.google.errorprone.annotations.CanIgnoreReturnValue; 024import java.util.Arrays; 025import java.util.Comparator; 026 027/** 028 * Static utility methods pertaining to {@code int} primitives that interpret values as 029 * <i>unsigned</i> (that is, any negative value {@code x} is treated as the positive value {@code 030 * 2^32 + x}). The methods for which signedness is not an issue are in {@link Ints}, as well as 031 * signed versions of methods for which signedness is an issue. 032 * 033 * <p>In addition, this class provides several static methods for converting an {@code int} to a 034 * {@code String} and a {@code String} to an {@code int} that treat the {@code int} as an unsigned 035 * number. 036 * 037 * <p>Users of these utilities must be <i>extremely careful</i> not to mix up signed and unsigned 038 * {@code int} values. When possible, it is recommended that the {@link UnsignedInteger} wrapper 039 * class be used, at a small efficiency penalty, to enforce the distinction in the type system. 040 * 041 * <p>See the Guava User Guide article on <a 042 * href="https://github.com/google/guava/wiki/PrimitivesExplained#unsigned-support">unsigned 043 * primitive utilities</a>. 044 * 045 * @author Louis Wasserman 046 * @since 11.0 047 */ 048@Beta 049@GwtCompatible 050@ElementTypesAreNonnullByDefault 051public final class UnsignedInts { 052 static final long INT_MASK = 0xffffffffL; 053 054 private UnsignedInts() {} 055 056 static int flip(int value) { 057 return value ^ Integer.MIN_VALUE; 058 } 059 060 /** 061 * Compares the two specified {@code int} values, treating them as unsigned values between {@code 062 * 0} and {@code 2^32 - 1} inclusive. 063 * 064 * <p><b>Java 8 users:</b> use {@link Integer#compareUnsigned(int, int)} instead. 065 * 066 * @param a the first unsigned {@code int} to compare 067 * @param b the second unsigned {@code int} to compare 068 * @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is 069 * greater than {@code b}; or zero if they are equal 070 */ 071 public static int compare(int a, int b) { 072 return Ints.compare(flip(a), flip(b)); 073 } 074 075 /** 076 * Returns the value of the given {@code int} as a {@code long}, when treated as unsigned. 077 * 078 * <p><b>Java 8 users:</b> use {@link Integer#toUnsignedLong(int)} instead. 079 */ 080 public static long toLong(int value) { 081 return value & INT_MASK; 082 } 083 084 /** 085 * Returns the {@code int} value that, when treated as unsigned, is equal to {@code value}, if 086 * possible. 087 * 088 * @param value a value between 0 and 2<sup>32</sup>-1 inclusive 089 * @return the {@code int} value that, when treated as unsigned, equals {@code value} 090 * @throws IllegalArgumentException if {@code value} is negative or greater than or equal to 091 * 2<sup>32</sup> 092 * @since 21.0 093 */ 094 public static int checkedCast(long value) { 095 checkArgument((value >> Integer.SIZE) == 0, "out of range: %s", value); 096 return (int) value; 097 } 098 099 /** 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}