| /* |
| * 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; |
| |
| /** |
| * 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= |
| * "http://code.google.com/p/guava-libraries/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 |
| */ |
| 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. |
| */ |
| 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 |
| */ |
| 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 |
| */ |
| 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 |
| */ |
| 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> |
| */ |
| 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 |
| */ |
| 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 |
| */ |
| 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. |
| */ |
| 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}. |
| */ |
| public static String toString(int x, int radix) { |
| long asLong = x & INT_MASK; |
| return Long.toString(asLong, radix); |
| } |
| } |