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/* * Copyright (C) 2011 The Guava Authors * * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except * in compliance with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software distributed under the * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either * express or implied. See the License for the specific language governing permissions and * limitations under the License. */ package com.google.common.primitives; import static com.google.common.base.Preconditions.checkArgument; import static com.google.common.base.Preconditions.checkNotNull; import com.google.common.annotations.Beta; import com.google.common.annotations.GwtCompatible; import java.util.Arrays; import java.util.Comparator; import javax.annotation.CheckReturnValue; /** * Static utility methods pertaining to {@code int} primitives that interpret values as * <i>unsigned</i> (that is, any negative value {@code x} is treated as the positive value * {@code 2^32 + x}). The methods for which signedness is not an issue are in {@link Ints}, as well * as signed versions of methods for which signedness is an issue. * * <p>In addition, this class provides several static methods for converting an {@code int} to a * {@code String} and a {@code String} to an {@code int} that treat the {@code int} as an unsigned * number. * * <p>Users of these utilities must be <i>extremely careful</i> not to mix up signed and unsigned * {@code int} values. When possible, it is recommended that the {@link UnsignedInteger} wrapper * class be used, at a small efficiency penalty, to enforce the distinction in the type system. * * <p>See the Guava User Guide article on <a href= * "https://github.com/google/guava/wiki/PrimitivesExplained#unsigned-support"> * unsigned primitive utilities</a>. * * @author Louis Wasserman * @since 11.0 */ @Beta @GwtCompatible public final class UnsignedInts { static final long INT_MASK = 0xffffffffL; private UnsignedInts() { } static int flip(int value) { return value ^ Integer.MIN_VALUE; } /** * Compares the two specified {@code int} values, treating them as unsigned values between * {@code 0} and {@code 2^32 - 1} inclusive. * * @param a the first unsigned {@code int} to compare * @param b the second unsigned {@code int} to compare * @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is * greater than {@code b}; or zero if they are equal */ @CheckReturnValue public static int compare(int a, int b) { return Ints.compare(flip(a), flip(b)); } /** * Returns the value of the given {@code int} as a {@code long}, when treated as unsigned. */ @CheckReturnValue public static long toLong(int value) { return value & INT_MASK; } /** * Returns the least value present in {@code array}, treating values as unsigned. * * @param array a <i>nonempty</i> array of unsigned {@code int} values * @return the value present in {@code array} that is less than or equal to every other value in * the array according to {@link #compare} * @throws IllegalArgumentException if {@code array} is empty */ @CheckReturnValue public static int min(int... array) { checkArgument(array.length > 0); int min = flip(array[0]); for (int i = 1; i < array.length; i++) { int next = flip(array[i]); if (next < min) { min = next; } } return flip(min); } /** * Returns the greatest value present in {@code array}, treating values as unsigned. * * @param array a <i>nonempty</i> array of unsigned {@code int} values * @return the value present in {@code array} that is greater than or equal to every other value * in the array according to {@link #compare} * @throws IllegalArgumentException if {@code array} is empty */ @CheckReturnValue public static int max(int... array) { checkArgument(array.length > 0); int max = flip(array[0]); for (int i = 1; i < array.length; i++) { int next = flip(array[i]); if (next > max) { max = next; } } return flip(max); } /** * Returns a string containing the supplied unsigned {@code int} values separated by * {@code separator}. For example, {@code join("-", 1, 2, 3)} returns the string {@code "1-2-3"}. * * @param separator the text that should appear between consecutive values in the resulting * string (but not at the start or end) * @param array an array of unsigned {@code int} values, possibly empty */ @CheckReturnValue public static String join(String separator, int... array) { checkNotNull(separator); if (array.length == 0) { return ""; } // For pre-sizing a builder, just get the right order of magnitude StringBuilder builder = new StringBuilder(array.length * 5); builder.append(toString(array[0])); for (int i = 1; i < array.length; i++) { builder.append(separator).append(toString(array[i])); } return builder.toString(); } /** * Returns a comparator that compares two arrays of unsigned {@code int} values lexicographically. * That is, it compares, using {@link #compare(int, int)}), the first pair of values that follow * any common prefix, or when one array is a prefix of the other, treats the shorter array as the * lesser. For example, {@code [] < [1] < [1, 2] < [2] < [1 << 31]}. * * <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays * support only identity equality), but it is consistent with {@link Arrays#equals(int[], int[])}. * * @see <a href="http://en.wikipedia.org/wiki/Lexicographical_order"> Lexicographical order * article at Wikipedia</a> */ @CheckReturnValue public static Comparator<int[]> lexicographicalComparator() { return LexicographicalComparator.INSTANCE; } enum LexicographicalComparator implements Comparator<int[]> { INSTANCE; @Override public int compare(int[] left, int[] right) { int minLength = Math.min(left.length, right.length); for (int i = 0; i < minLength; i++) { if (left[i] != right[i]) { return UnsignedInts.compare(left[i], right[i]); } } return left.length - right.length; } } /** * Returns dividend / divisor, where the dividend and divisor are treated as unsigned 32-bit * quantities. * * @param dividend the dividend (numerator) * @param divisor the divisor (denominator) * @throws ArithmeticException if divisor is 0 */ @CheckReturnValue public static int divide(int dividend, int divisor) { return (int) (toLong(dividend) / toLong(divisor)); } /** * Returns dividend % divisor, where the dividend and divisor are treated as unsigned 32-bit * quantities. * * @param dividend the dividend (numerator) * @param divisor the divisor (denominator) * @throws ArithmeticException if divisor is 0 */ @CheckReturnValue public static int remainder(int dividend, int divisor) { return (int) (toLong(dividend) % toLong(divisor)); } /** * Returns the unsigned {@code int} value represented by the given string. * * Accepts a decimal, hexadecimal, or octal number given by specifying the following prefix: * * <ul> * <li>{@code 0x}<i>HexDigits</i> * <li>{@code 0X}<i>HexDigits</i> * <li>{@code #}<i>HexDigits</i> * <li>{@code 0}<i>OctalDigits</i> * </ul> * * @throws NumberFormatException if the string does not contain a valid unsigned {@code int} value * @since 13.0 */ public static int decode(String stringValue) { ParseRequest request = ParseRequest.fromString(stringValue); try { return parseUnsignedInt(request.rawValue, request.radix); } catch (NumberFormatException e) { NumberFormatException decodeException = new NumberFormatException( "Error parsing value: " + stringValue); decodeException.initCause(e); throw decodeException; } } /** * Returns the unsigned {@code int} value represented by the given decimal string. * * @throws NumberFormatException if the string does not contain a valid unsigned {@code int} value * @throws NullPointerException if {@code s} is null * (in contrast to {@link Integer#parseInt(String)}) */ public static int parseUnsignedInt(String s) { return parseUnsignedInt(s, 10); } /** * Returns the unsigned {@code int} value represented by a string with the given radix. * * @param string the string containing the unsigned integer representation to be parsed. * @param radix the radix to use while parsing {@code s}; must be between * {@link Character#MIN_RADIX} and {@link Character#MAX_RADIX}. * @throws NumberFormatException if the string does not contain a valid unsigned {@code int}, or * if supplied radix is invalid. * @throws NullPointerException if {@code s} is null * (in contrast to {@link Integer#parseInt(String)}) */ public static int parseUnsignedInt(String string, int radix) { checkNotNull(string); long result = Long.parseLong(string, radix); if ((result & INT_MASK) != result) { throw new NumberFormatException( "Input " + string + " in base " + radix + " is not in the range of an unsigned integer"); } return (int) result; } /** * Returns a string representation of x, where x is treated as unsigned. */ @CheckReturnValue public static String toString(int x) { return toString(x, 10); } /** * Returns a string representation of {@code x} for the given radix, where {@code x} is treated * as unsigned. * * @param x the value to convert to a string. * @param radix the radix to use while working with {@code x} * @throws IllegalArgumentException if {@code radix} is not between {@link Character#MIN_RADIX} * and {@link Character#MAX_RADIX}. */ @CheckReturnValue public static String toString(int x, int radix) { long asLong = x & INT_MASK; return Long.toString(asLong, radix); } }