com.google.common.primitives.UnsignedBytes Maven / Gradle / Ivy
/*
* Copyright (C) 2009 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 com.google.common.annotations.Beta;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.VisibleForTesting;
import java.util.Arrays;
import java.util.Comparator;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkPositionIndexes;
/**
* Static utility methods pertaining to {@code byte} primitives that interpret values as
* unsigned (that is, any negative value {@code b} is treated as the positive value {@code
* 256 + b}). The corresponding methods that treat the values as signed are found in {@link
* SignedBytes}, and the methods for which signedness is not an issue are in {@link Bytes}.
*
* See the Guava User Guide article on primitive utilities.
*
* @author Kevin Bourrillion
* @author Martin Buchholz
* @author Hiroshi Yamauchi
* @author Louis Wasserman
* @since 1.0
*/
@GwtIncompatible
public final class UnsignedBytes {
private UnsignedBytes() {}
/**
* The largest power of two that can be represented as an unsigned {@code byte}.
*
* @since 10.0
*/
public static final byte MAX_POWER_OF_TWO = (byte) 0x80;
/**
* The largest value that fits into an unsigned byte.
*
* @since 13.0
*/
public static final byte MAX_VALUE = (byte) 0xFF;
private static final int UNSIGNED_MASK = 0xFF;
/**
* Returns the value of the given byte as an integer, when treated as unsigned. That is, returns
* {@code value + 256} if {@code value} is negative; {@code value} itself otherwise.
*
*
Java 8 users: use {@link Byte#toUnsignedInt(byte)} instead.
*
* @since 6.0
*/
public static int toInt(byte value) {
return value & UNSIGNED_MASK;
}
/**
* Returns the {@code byte} value that, when treated as unsigned, is equal to {@code value}, if
* possible.
*
* @param value a value between 0 and 255 inclusive
* @return the {@code byte} value that, when treated as unsigned, equals {@code value}
* @throws IllegalArgumentException if {@code value} is negative or greater than 255
*/
public static byte checkedCast(long value) {
checkArgument(value >> Byte.SIZE == 0, "out of range: %s", value);
return (byte) value;
}
/**
* Returns the {@code byte} value that, when treated as unsigned, is nearest in value to {@code
* value}.
*
* @param value any {@code long} value
* @return {@code (byte) 255} if {@code value >= 255}, {@code (byte) 0} if {@code value <= 0}, and
* {@code value} cast to {@code byte} otherwise
*/
public static byte saturatedCast(long value) {
if (value > toInt(MAX_VALUE)) {
return MAX_VALUE; // -1
}
if (value < 0) {
return (byte) 0;
}
return (byte) value;
}
/**
* Compares the two specified {@code byte} values, treating them as unsigned values between 0 and
* 255 inclusive. For example, {@code (byte) -127} is considered greater than {@code (byte) 127}
* because it is seen as having the value of positive {@code 129}.
*
* @param a the first {@code byte} to compare
* @param b the second {@code byte} 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(byte a, byte b) {
return toInt(a) - toInt(b);
}
/**
* Returns the least value present in {@code array}.
*
* @param array a nonempty array of {@code byte} values
* @return the value present in {@code array} that is less than or equal to every other value in
* the array
* @throws IllegalArgumentException if {@code array} is empty
*/
public static byte min(byte... array) {
checkArgument(array.length > 0);
int min = toInt(array[0]);
for (int i = 1; i < array.length; i++) {
int next = toInt(array[i]);
if (next < min) {
min = next;
}
}
return (byte) min;
}
/**
* Returns the greatest value present in {@code array}.
*
* @param array a nonempty array of {@code byte} values
* @return the value present in {@code array} that is greater than or equal to every other value
* in the array
* @throws IllegalArgumentException if {@code array} is empty
*/
public static byte max(byte... array) {
checkArgument(array.length > 0);
int max = toInt(array[0]);
for (int i = 1; i < array.length; i++) {
int next = toInt(array[i]);
if (next > max) {
max = next;
}
}
return (byte) max;
}
/**
* Returns a string representation of x, where x is treated as unsigned.
*
* @since 13.0
*/
@Beta
public static String toString(byte 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}.
* @since 13.0
*/
@Beta
public static String toString(byte x, int radix) {
checkArgument(
radix >= Character.MIN_RADIX && radix <= Character.MAX_RADIX,
"radix (%s) must be between Character.MIN_RADIX and Character.MAX_RADIX",
radix);
// Benchmarks indicate this is probably not worth optimizing.
return Integer.toString(toInt(x), radix);
}
/**
* Returns the unsigned {@code byte} value represented by the given decimal string.
*
* @throws NumberFormatException if the string does not contain a valid unsigned {@code byte}
* value
* @throws NullPointerException if {@code string} is null (in contrast to {@link
* Byte#parseByte(String)})
* @since 13.0
*/
@Beta
public static byte parseUnsignedByte(String string) {
return parseUnsignedByte(string, 10);
}
/**
* Returns the unsigned {@code byte} value represented by a string with the given radix.
*
* @param string the string containing the unsigned {@code byte} representation to be parsed.
* @param radix the radix to use while parsing {@code string}
* @throws NumberFormatException if the string does not contain a valid unsigned {@code byte} with
* the given radix, or if {@code radix} is not between {@link Character#MIN_RADIX} and {@link
* Character#MAX_RADIX}.
* @throws NullPointerException if {@code string} is null (in contrast to {@link
* Byte#parseByte(String)})
* @since 13.0
*/
@Beta
public static byte parseUnsignedByte(String string, int radix) {
int parse = Integer.parseInt(checkNotNull(string), radix);
// We need to throw a NumberFormatException, so we have to duplicate checkedCast. =(
if (parse >> Byte.SIZE == 0) {
return (byte) parse;
} else {
throw new NumberFormatException("out of range: " + parse);
}
}
/**
* Returns a string containing the supplied {@code byte} values separated by {@code separator}.
* For example, {@code join(":", (byte) 1, (byte) 2, (byte) 255)} returns the string {@code
* "1:2:255"}.
*
* @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 {@code byte} values, possibly empty
*/
public static String join(String separator, byte... 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 * (3 + separator.length()));
builder.append(toInt(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 {@code byte} arrays lexicographically. That is, it
* compares, using {@link #compare(byte, byte)}), 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 [] < [0x01] < [0x01, 0x7F] < [0x01, 0x80] < [0x02]}. Values are treated as
* unsigned.
*
*
The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays
* support only identity equality), but it is consistent with {@link
* Arrays#equals(byte[], byte[])}.
*
* @since 2.0
*/
public static Comparator lexicographicalComparator() {
return LexicographicalComparatorHolder.BEST_COMPARATOR;
}
@VisibleForTesting
static Comparator lexicographicalComparatorJavaImpl() {
return LexicographicalComparatorHolder.PureJavaComparator.INSTANCE;
}
/**
* Provides a lexicographical comparator implementation.
*
* Uses reflection to gracefully fall back to the Java implementation if {@code Unsafe} isn't
* available.
*/
@VisibleForTesting
static class LexicographicalComparatorHolder {
static final Comparator BEST_COMPARATOR = getBestComparator();
enum PureJavaComparator implements Comparator {
INSTANCE;
@Override
public int compare(byte[] left, byte[] right) {
int minLength = Math.min(left.length, right.length);
for (int i = 0; i < minLength; i++) {
int result = UnsignedBytes.compare(left[i], right[i]);
if (result != 0) {
return result;
}
}
return left.length - right.length;
}
@Override
public String toString() {
return "UnsignedBytes.lexicographicalComparator() (pure Java version)";
}
}
/**
* Returns the Unsafe-using Comparator, or falls back to the pure-Java implementation if unable
* to do so.
*/
static Comparator getBestComparator() {
return lexicographicalComparatorJavaImpl();
}
}
private static byte flip(byte b) {
return (byte) (b ^ 0x80);
}
/**
* Sorts the array, treating its elements as unsigned bytes.
*
* @since 23.1
*/
public static void sort(byte[] array) {
checkNotNull(array);
sort(array, 0, array.length);
}
/**
* Sorts the array between {@code fromIndex} inclusive and {@code toIndex} exclusive, treating its
* elements as unsigned bytes.
*
* @since 23.1
*/
public static void sort(byte[] array, int fromIndex, int toIndex) {
checkNotNull(array);
checkPositionIndexes(fromIndex, toIndex, array.length);
for (int i = fromIndex; i < toIndex; i++) {
array[i] = flip(array[i]);
}
Arrays.sort(array, fromIndex, toIndex);
for (int i = fromIndex; i < toIndex; i++) {
array[i] = flip(array[i]);
}
}
/**
* Sorts the elements of {@code array} in descending order, interpreting them as unsigned 8-bit
* integers.
*
* @since 23.1
*/
public static void sortDescending(byte[] array) {
checkNotNull(array);
sortDescending(array, 0, array.length);
}
/**
* Sorts the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex}
* exclusive in descending order, interpreting them as unsigned 8-bit integers.
*
* @since 23.1
*/
public static void sortDescending(byte[] array, int fromIndex, int toIndex) {
checkNotNull(array);
checkPositionIndexes(fromIndex, toIndex, array.length);
for (int i = fromIndex; i < toIndex; i++) {
array[i] ^= Byte.MAX_VALUE;
}
Arrays.sort(array, fromIndex, toIndex);
for (int i = fromIndex; i < toIndex; i++) {
array[i] ^= Byte.MAX_VALUE;
}
}
}