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 050public final class UnsignedInts { 051 static final long INT_MASK = 0xffffffffL; 052 053 private UnsignedInts() {} 054 055 static int flip(int value) { 056 return value ^ Integer.MIN_VALUE; 057 } 058 059 /** 060 * Compares the two specified {@code int} values, treating them as unsigned values between {@code 061 * 0} and {@code 2^32 - 1} inclusive. 062 * 063 * <p><b>Java 8 users:</b> use {@link Integer#compareUnsigned(int, int)} instead. 064 * 065 * @param a the first unsigned {@code int} to compare 066 * @param b the second unsigned {@code int} to compare 067 * @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is 068 * greater than {@code b}; or zero if they are equal 069 */ 070 public static int compare(int a, int b) { 071 return Ints.compare(flip(a), flip(b)); 072 } 073 074 /** 075 * Returns the value of the given {@code int} as a {@code long}, when treated as unsigned. 076 * 077 * <p><b>Java 8 users:</b> use {@link Integer#toUnsignedLong(int)} instead. 078 */ 079 public static long toLong(int value) { 080 return value & INT_MASK; 081 } 082 083 /** 084 * Returns the {@code int} value that, when treated as unsigned, is equal to {@code value}, if 085 * possible. 086 * 087 * @param value a value between 0 and 2<sup>32</sup>-1 inclusive 088 * @return the {@code int} value that, when treated as unsigned, equals {@code value} 089 * @throws IllegalArgumentException if {@code value} is negative or greater than or equal to 090 * 2<sup>32</sup> 091 * @since 21.0 092 */ 093 public static int checkedCast(long value) { 094 checkArgument((value >> Integer.SIZE) == 0, "out of range: %s", value); 095 return (int) value; 096 } 097 098 /** 099 * Returns the {@code int} value that, when treated as unsigned, is nearest in value to {@code 100 * value}. 101 * 102 * @param value any {@code long} value 103 * @return {@code 2^32 - 1} if {@code value >= 2^32}, {@code 0} if {@code value <= 0}, and {@code 104 * value} cast to {@code int} otherwise 105 * @since 21.0 106 */ 107 public static int saturatedCast(long value) { 108 if (value <= 0) { 109 return 0; 110 } else if (value >= (1L << 32)) { 111 return -1; 112 } else { 113 return (int) value; 114 } 115 } 116 117 /** 118 * Returns the least value present in {@code array}, treating values as unsigned. 119 * 120 * @param array a <i>nonempty</i> array of unsigned {@code int} values 121 * @return the value present in {@code array} that is less than or equal to every other value in 122 * the array according to {@link #compare} 123 * @throws IllegalArgumentException if {@code array} is empty 124 */ 125 public static int min(int... array) { 126 checkArgument(array.length > 0); 127 int min = flip(array[0]); 128 for (int i = 1; i < array.length; i++) { 129 int next = flip(array[i]); 130 if (next < min) { 131 min = next; 132 } 133 } 134 return flip(min); 135 } 136 137 /** 138 * Returns the greatest value present in {@code array}, treating values as unsigned. 139 * 140 * @param array a <i>nonempty</i> array of unsigned {@code int} values 141 * @return the value present in {@code array} that is greater than or equal to every other value 142 * in the array according to {@link #compare} 143 * @throws IllegalArgumentException if {@code array} is empty 144 */ 145 public static int max(int... array) { 146 checkArgument(array.length > 0); 147 int max = flip(array[0]); 148 for (int i = 1; i < array.length; i++) { 149 int next = flip(array[i]); 150 if (next > max) { 151 max = next; 152 } 153 } 154 return flip(max); 155 } 156 157 /** 158 * Returns a string containing the supplied unsigned {@code int} values separated by {@code 159 * separator}. For example, {@code join("-", 1, 2, 3)} returns the string {@code "1-2-3"}. 160 * 161 * @param separator the text that should appear between consecutive values in the resulting string 162 * (but not at the start or end) 163 * @param array an array of unsigned {@code int} values, possibly empty 164 */ 165 public static String join(String separator, int... array) { 166 checkNotNull(separator); 167 if (array.length == 0) { 168 return ""; 169 } 170 171 // For pre-sizing a builder, just get the right order of magnitude 172 StringBuilder builder = new StringBuilder(array.length * 5); 173 builder.append(toString(array[0])); 174 for (int i = 1; i < array.length; i++) { 175 builder.append(separator).append(toString(array[i])); 176 } 177 return builder.toString(); 178 } 179 180 /** 181 * Returns a comparator that compares two arrays of unsigned {@code int} values <a 182 * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it 183 * compares, using {@link #compare(int, int)}), the first pair of values that follow any common 184 * prefix, or when one array is a prefix of the other, treats the shorter array as the lesser. For 185 * example, {@code [] < [1] < [1, 2] < [2] < [1 << 31]}. 186 * 187 * <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays 188 * support only identity equality), but it is consistent with {@link Arrays#equals(int[], int[])}. 189 */ 190 public static Comparator<int[]> lexicographicalComparator() { 191 return LexicographicalComparator.INSTANCE; 192 } 193 194 enum LexicographicalComparator implements Comparator<int[]> { 195 INSTANCE; 196 197 @Override 198 public int compare(int[] left, int[] right) { 199 int minLength = Math.min(left.length, right.length); 200 for (int i = 0; i < minLength; i++) { 201 if (left[i] != right[i]) { 202 return UnsignedInts.compare(left[i], right[i]); 203 } 204 } 205 return left.length - right.length; 206 } 207 208 @Override 209 public String toString() { 210 return "UnsignedInts.lexicographicalComparator()"; 211 } 212 } 213 214 /** 215 * Sorts the array, treating its elements as unsigned 32-bit integers. 216 * 217 * @since 23.1 218 */ 219 public static void sort(int[] array) { 220 checkNotNull(array); 221 sort(array, 0, array.length); 222 } 223 224 /** 225 * Sorts the array between {@code fromIndex} inclusive and {@code toIndex} exclusive, treating its 226 * elements as unsigned 32-bit integers. 227 * 228 * @since 23.1 229 */ 230 public static void sort(int[] array, int fromIndex, int toIndex) { 231 checkNotNull(array); 232 checkPositionIndexes(fromIndex, toIndex, array.length); 233 for (int i = fromIndex; i < toIndex; i++) { 234 array[i] = flip(array[i]); 235 } 236 Arrays.sort(array, fromIndex, toIndex); 237 for (int i = fromIndex; i < toIndex; i++) { 238 array[i] = flip(array[i]); 239 } 240 } 241 242 /** 243 * Sorts the elements of {@code array} in descending order, interpreting them as unsigned 32-bit 244 * integers. 245 * 246 * @since 23.1 247 */ 248 public static void sortDescending(int[] array) { 249 checkNotNull(array); 250 sortDescending(array, 0, array.length); 251 } 252 253 /** 254 * Sorts the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex} 255 * exclusive in descending order, interpreting them as unsigned 32-bit integers. 256 * 257 * @since 23.1 258 */ 259 public static void sortDescending(int[] array, int fromIndex, int toIndex) { 260 checkNotNull(array); 261 checkPositionIndexes(fromIndex, toIndex, array.length); 262 for (int i = fromIndex; i < toIndex; i++) { 263 array[i] ^= Integer.MAX_VALUE; 264 } 265 Arrays.sort(array, fromIndex, toIndex); 266 for (int i = fromIndex; i < toIndex; i++) { 267 array[i] ^= Integer.MAX_VALUE; 268 } 269 } 270 271 /** 272 * Returns dividend / divisor, where the dividend and divisor are treated as unsigned 32-bit 273 * quantities. 274 * 275 * <p><b>Java 8 users:</b> use {@link Integer#divideUnsigned(int, int)} instead. 276 * 277 * @param dividend the dividend (numerator) 278 * @param divisor the divisor (denominator) 279 * @throws ArithmeticException if divisor is 0 280 */ 281 public static int divide(int dividend, int divisor) { 282 return (int) (toLong(dividend) / toLong(divisor)); 283 } 284 285 /** 286 * Returns dividend % divisor, where the dividend and divisor are treated as unsigned 32-bit 287 * quantities. 288 * 289 * <p><b>Java 8 users:</b> use {@link Integer#remainderUnsigned(int, int)} instead. 290 * 291 * @param dividend the dividend (numerator) 292 * @param divisor the divisor (denominator) 293 * @throws ArithmeticException if divisor is 0 294 */ 295 public static int remainder(int dividend, int divisor) { 296 return (int) (toLong(dividend) % toLong(divisor)); 297 } 298 299 /** 300 * Returns the unsigned {@code int} value represented by the given string. 301 * 302 * <p>Accepts a decimal, hexadecimal, or octal number given by specifying the following prefix: 303 * 304 * <ul> 305 * <li>{@code 0x}<i>HexDigits</i> 306 * <li>{@code 0X}<i>HexDigits</i> 307 * <li>{@code #}<i>HexDigits</i> 308 * <li>{@code 0}<i>OctalDigits</i> 309 * </ul> 310 * 311 * @throws NumberFormatException if the string does not contain a valid unsigned {@code int} value 312 * @since 13.0 313 */ 314 @CanIgnoreReturnValue 315 public static int decode(String stringValue) { 316 ParseRequest request = ParseRequest.fromString(stringValue); 317 318 try { 319 return parseUnsignedInt(request.rawValue, request.radix); 320 } catch (NumberFormatException e) { 321 NumberFormatException decodeException = 322 new NumberFormatException("Error parsing value: " + stringValue); 323 decodeException.initCause(e); 324 throw decodeException; 325 } 326 } 327 328 /** 329 * Returns the unsigned {@code int} value represented by the given decimal string. 330 * 331 * <p><b>Java 8 users:</b> use {@link Integer#parseUnsignedInt(String)} instead. 332 * 333 * @throws NumberFormatException if the string does not contain a valid unsigned {@code int} value 334 * @throws NullPointerException if {@code s} is null (in contrast to {@link 335 * Integer#parseInt(String)}) 336 */ 337 @CanIgnoreReturnValue 338 public static int parseUnsignedInt(String s) { 339 return parseUnsignedInt(s, 10); 340 } 341 342 /** 343 * Returns the unsigned {@code int} value represented by a string with the given radix. 344 * 345 * <p><b>Java 8 users:</b> use {@link Integer#parseUnsignedInt(String, int)} instead. 346 * 347 * @param string the string containing the unsigned integer representation to be parsed. 348 * @param radix the radix to use while parsing {@code s}; must be between {@link 349 * Character#MIN_RADIX} and {@link Character#MAX_RADIX}. 350 * @throws NumberFormatException if the string does not contain a valid unsigned {@code int}, or 351 * if supplied radix is invalid. 352 * @throws NullPointerException if {@code s} is null (in contrast to {@link 353 * Integer#parseInt(String)}) 354 */ 355 @CanIgnoreReturnValue 356 public static int parseUnsignedInt(String string, int radix) { 357 checkNotNull(string); 358 long result = Long.parseLong(string, radix); 359 if ((result & INT_MASK) != result) { 360 throw new NumberFormatException( 361 "Input " + string + " in base " + radix + " is not in the range of an unsigned integer"); 362 } 363 return (int) result; 364 } 365 366 /** 367 * Returns a string representation of x, where x is treated as unsigned. 368 * 369 * <p><b>Java 8 users:</b> use {@link Integer#toUnsignedString(int)} instead. 370 */ 371 public static String toString(int x) { 372 return toString(x, 10); 373 } 374 375 /** 376 * Returns a string representation of {@code x} for the given radix, where {@code x} is treated as 377 * unsigned. 378 * 379 * <p><b>Java 8 users:</b> use {@link Integer#toUnsignedString(int, int)} instead. 380 * 381 * @param x the value to convert to a string. 382 * @param radix the radix to use while working with {@code x} 383 * @throws IllegalArgumentException if {@code radix} is not between {@link Character#MIN_RADIX} 384 * and {@link Character#MAX_RADIX}. 385 */ 386 public static String toString(int x, int radix) { 387 long asLong = x & INT_MASK; 388 return Long.toString(asLong, radix); 389 } 390}