| /* |
| * 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 static com.google.common.base.Preconditions.checkArgument; |
| import static com.google.common.base.Preconditions.checkNotNull; |
| import static com.google.common.base.Preconditions.checkPositionIndexes; |
| |
| import com.google.common.annotations.GwtCompatible; |
| import java.util.Arrays; |
| import java.util.Comparator; |
| |
| /** |
| * Static utility methods pertaining to {@code byte} primitives that interpret values as signed. The |
| * corresponding methods that treat the values as unsigned are found in {@link UnsignedBytes}, and |
| * the methods for which signedness is not an issue are in {@link Bytes}. |
| * |
| * <p>See the Guava User Guide article on <a |
| * href="https://github.com/google/guava/wiki/PrimitivesExplained">primitive utilities</a>. |
| * |
| * @author Kevin Bourrillion |
| * @since 1.0 |
| */ |
| // TODO(kevinb): how to prevent warning on UnsignedBytes when building GWT |
| // javadoc? |
| @GwtCompatible |
| public final class SignedBytes { |
| private SignedBytes() {} |
| |
| /** |
| * The largest power of two that can be represented as a signed {@code byte}. |
| * |
| * @since 10.0 |
| */ |
| public static final byte MAX_POWER_OF_TWO = 1 << 6; |
| |
| /** |
| * Returns the {@code byte} value that is equal to {@code value}, if possible. |
| * |
| * @param value any value in the range of the {@code byte} type |
| * @return the {@code byte} value that equals {@code value} |
| * @throws IllegalArgumentException if {@code value} is greater than {@link Byte#MAX_VALUE} or |
| * less than {@link Byte#MIN_VALUE} |
| */ |
| public static byte checkedCast(long value) { |
| byte result = (byte) value; |
| checkArgument(result == value, "Out of range: %s", value); |
| return result; |
| } |
| |
| /** |
| * Returns the {@code byte} nearest in value to {@code value}. |
| * |
| * @param value any {@code long} value |
| * @return the same value cast to {@code byte} if it is in the range of the {@code byte} type, |
| * {@link Byte#MAX_VALUE} if it is too large, or {@link Byte#MIN_VALUE} if it is too small |
| */ |
| public static byte saturatedCast(long value) { |
| if (value > Byte.MAX_VALUE) { |
| return Byte.MAX_VALUE; |
| } |
| if (value < Byte.MIN_VALUE) { |
| return Byte.MIN_VALUE; |
| } |
| return (byte) value; |
| } |
| |
| /** |
| * Compares the two specified {@code byte} values. The sign of the value returned is the same as |
| * that of {@code ((Byte) a).compareTo(b)}. |
| * |
| * <p><b>Note:</b> this method behaves identically to the JDK 7 method {@link Byte#compare}. |
| * |
| * @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 |
| */ |
| // TODO(kevinb): if Ints.compare etc. are ever removed, *maybe* remove this |
| // one too, which would leave compare methods only on the Unsigned* classes. |
| public static int compare(byte a, byte b) { |
| return a - b; // safe due to restricted range |
| } |
| |
| /** |
| * Returns the least value present in {@code array}. |
| * |
| * @param array a <i>nonempty</i> 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); |
| byte min = array[0]; |
| for (int i = 1; i < array.length; i++) { |
| if (array[i] < min) { |
| min = array[i]; |
| } |
| } |
| return min; |
| } |
| |
| /** |
| * Returns the greatest value present in {@code array}. |
| * |
| * @param array a <i>nonempty</i> 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); |
| byte max = array[0]; |
| for (int i = 1; i < array.length; i++) { |
| if (array[i] > max) { |
| max = array[i]; |
| } |
| } |
| return max; |
| } |
| |
| /** |
| * Returns a string containing the supplied {@code byte} values separated by {@code separator}. |
| * For example, {@code join(":", 0x01, 0x02, -0x01)} returns the string {@code "1:2:-1"}. |
| * |
| * @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 * 5); |
| builder.append(array[0]); |
| for (int i = 1; i < array.length; i++) { |
| builder.append(separator).append(array[i]); |
| } |
| return builder.toString(); |
| } |
| |
| /** |
| * Returns a comparator that compares two {@code byte} arrays <a |
| * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. 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, 0x80] < [0x01, 0x7F] < [0x02]}. Values are treated as |
| * signed. |
| * |
| * <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays |
| * support only identity equality), but it is consistent with {@link |
| * java.util.Arrays#equals(byte[], byte[])}. |
| * |
| * @since 2.0 |
| */ |
| public static Comparator<byte[]> lexicographicalComparator() { |
| return LexicographicalComparator.INSTANCE; |
| } |
| |
| private enum LexicographicalComparator implements Comparator<byte[]> { |
| 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 = SignedBytes.compare(left[i], right[i]); |
| if (result != 0) { |
| return result; |
| } |
| } |
| return left.length - right.length; |
| } |
| |
| @Override |
| public String toString() { |
| return "SignedBytes.lexicographicalComparator()"; |
| } |
| } |
| |
| /** |
| * Sorts the elements of {@code array} in descending order. |
| * |
| * @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. |
| * |
| * @since 23.1 |
| */ |
| public static void sortDescending(byte[] array, int fromIndex, int toIndex) { |
| checkNotNull(array); |
| checkPositionIndexes(fromIndex, toIndex, array.length); |
| Arrays.sort(array, fromIndex, toIndex); |
| Bytes.reverse(array, fromIndex, toIndex); |
| } |
| } |