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/*
 * Copyright (C) 2008 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.checkElementIndex;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkPositionIndexes;

import com.google.common.annotations.GwtCompatible;
import java.io.Serializable;
import java.util.AbstractList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.RandomAccess;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Static utility methods pertaining to {@code byte} primitives, that are not already found in
 * either {@link Byte} or {@link Arrays}, and interpret bytes as neither signed nor unsigned.
 * The methods which specifically treat bytes as signed or unsigned are found in {@link SignedBytes}
 * and {@link UnsignedBytes}.
 *
 * 

See the Guava User Guide article on primitive utilities. * * @author Kevin Bourrillion * @since 1.0 */ // TODO(kevinb): how to prevent warning on UnsignedBytes when building GWT // javadoc? @GwtCompatible public final class Bytes { private Bytes() {} /** * Returns a hash code for {@code value}; equal to the result of invoking {@code ((Byte) * value).hashCode()}. * *

Java 8 users: use {@link Byte#hashCode(byte)} instead. * * @param value a primitive {@code byte} value * @return a hash code for the value */ public static int hashCode(byte value) { return value; } /** * Returns {@code true} if {@code target} is present as an element anywhere in {@code array}. * * @param array an array of {@code byte} values, possibly empty * @param target a primitive {@code byte} value * @return {@code true} if {@code array[i] == target} for some value of {@code i} */ public static boolean contains(byte[] array, byte target) { for (byte value : array) { if (value == target) { return true; } } return false; } /** * Returns the index of the first appearance of the value {@code target} in {@code array}. * * @param array an array of {@code byte} values, possibly empty * @param target a primitive {@code byte} value * @return the least index {@code i} for which {@code array[i] == target}, or {@code -1} if no * such index exists. */ public static int indexOf(byte[] array, byte target) { return indexOf(array, target, 0, array.length); } // TODO(kevinb): consider making this public private static int indexOf(byte[] array, byte target, int start, int end) { for (int i = start; i < end; i++) { if (array[i] == target) { return i; } } return -1; } /** * Returns the start position of the first occurrence of the specified {@code target} within * {@code array}, or {@code -1} if there is no such occurrence. * *

More formally, returns the lowest index {@code i} such that {@code Arrays.copyOfRange(array, * i, i + target.length)} contains exactly the same elements as {@code target}. * * @param array the array to search for the sequence {@code target} * @param target the array to search for as a sub-sequence of {@code array} */ public static int indexOf(byte[] array, byte[] target) { checkNotNull(array, "array"); checkNotNull(target, "target"); if (target.length == 0) { return 0; } outer: for (int i = 0; i < array.length - target.length + 1; i++) { for (int j = 0; j < target.length; j++) { if (array[i + j] != target[j]) { continue outer; } } return i; } return -1; } /** * Returns the index of the last appearance of the value {@code target} in {@code array}. * * @param array an array of {@code byte} values, possibly empty * @param target a primitive {@code byte} value * @return the greatest index {@code i} for which {@code array[i] == target}, or {@code -1} if no * such index exists. */ public static int lastIndexOf(byte[] array, byte target) { return lastIndexOf(array, target, 0, array.length); } // TODO(kevinb): consider making this public private static int lastIndexOf(byte[] array, byte target, int start, int end) { for (int i = end - 1; i >= start; i--) { if (array[i] == target) { return i; } } return -1; } /** * Returns the values from each provided array combined into a single array. For example, {@code * concat(new byte[] {a, b}, new byte[] {}, new byte[] {c}} returns the array {@code {a, b, c}}. * * @param arrays zero or more {@code byte} arrays * @return a single array containing all the values from the source arrays, in order */ public static byte[] concat(byte[]... arrays) { int length = 0; for (byte[] array : arrays) { length += array.length; } byte[] result = new byte[length]; int pos = 0; for (byte[] array : arrays) { System.arraycopy(array, 0, result, pos, array.length); pos += array.length; } return result; } /** * Returns an array containing the same values as {@code array}, but guaranteed to be of a * specified minimum length. If {@code array} already has a length of at least {@code minLength}, * it is returned directly. Otherwise, a new array of size {@code minLength + padding} is * returned, containing the values of {@code array}, and zeroes in the remaining places. * * @param array the source array * @param minLength the minimum length the returned array must guarantee * @param padding an extra amount to "grow" the array by if growth is necessary * @throws IllegalArgumentException if {@code minLength} or {@code padding} is negative * @return an array containing the values of {@code array}, with guaranteed minimum length {@code * minLength} */ public static byte[] ensureCapacity(byte[] array, int minLength, int padding) { checkArgument(minLength >= 0, "Invalid minLength: %s", minLength); checkArgument(padding >= 0, "Invalid padding: %s", padding); return (array.length < minLength) ? Arrays.copyOf(array, minLength + padding) : array; } /** * Returns an array containing each value of {@code collection}, converted to a {@code byte} value * in the manner of {@link Number#byteValue}. * *

Elements are copied from the argument collection as if by {@code collection.toArray()}. * Calling this method is as thread-safe as calling that method. * * @param collection a collection of {@code Number} instances * @return an array containing the same values as {@code collection}, in the same order, converted * to primitives * @throws NullPointerException if {@code collection} or any of its elements is null * @since 1.0 (parameter was {@code Collection} before 12.0) */ public static byte[] toArray(Collection collection) { if (collection instanceof ByteArrayAsList) { return ((ByteArrayAsList) collection).toByteArray(); } Object[] boxedArray = collection.toArray(); int len = boxedArray.length; byte[] array = new byte[len]; for (int i = 0; i < len; i++) { // checkNotNull for GWT (do not optimize) array[i] = ((Number) checkNotNull(boxedArray[i])).byteValue(); } return array; } /** * Returns a fixed-size list backed by the specified array, similar to {@link * Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)}, but any attempt to * set a value to {@code null} will result in a {@link NullPointerException}. * *

The returned list maintains the values, but not the identities, of {@code Byte} objects * written to or read from it. For example, whether {@code list.get(0) == list.get(0)} is true for * the returned list is unspecified. * * @param backingArray the array to back the list * @return a list view of the array */ public static List asList(byte... backingArray) { if (backingArray.length == 0) { return Collections.emptyList(); } return new ByteArrayAsList(backingArray); } @GwtCompatible private static class ByteArrayAsList extends AbstractList implements RandomAccess, Serializable { final byte[] array; final int start; final int end; ByteArrayAsList(byte[] array) { this(array, 0, array.length); } ByteArrayAsList(byte[] array, int start, int end) { this.array = array; this.start = start; this.end = end; } @Override public int size() { return end - start; } @Override public boolean isEmpty() { return false; } @Override public Byte get(int index) { checkElementIndex(index, size()); return array[start + index]; } @Override public boolean contains(Object target) { // Overridden to prevent a ton of boxing return (target instanceof Byte) && Bytes.indexOf(array, (Byte) target, start, end) != -1; } @Override public int indexOf(Object target) { // Overridden to prevent a ton of boxing if (target instanceof Byte) { int i = Bytes.indexOf(array, (Byte) target, start, end); if (i >= 0) { return i - start; } } return -1; } @Override public int lastIndexOf(Object target) { // Overridden to prevent a ton of boxing if (target instanceof Byte) { int i = Bytes.lastIndexOf(array, (Byte) target, start, end); if (i >= 0) { return i - start; } } return -1; } @Override public Byte set(int index, Byte element) { checkElementIndex(index, size()); byte oldValue = array[start + index]; // checkNotNull for GWT (do not optimize) array[start + index] = checkNotNull(element); return oldValue; } @Override public List subList(int fromIndex, int toIndex) { int size = size(); checkPositionIndexes(fromIndex, toIndex, size); if (fromIndex == toIndex) { return Collections.emptyList(); } return new ByteArrayAsList(array, start + fromIndex, start + toIndex); } @Override public boolean equals(@Nullable Object object) { if (object == this) { return true; } if (object instanceof ByteArrayAsList) { ByteArrayAsList that = (ByteArrayAsList) object; int size = size(); if (that.size() != size) { return false; } for (int i = 0; i < size; i++) { if (array[start + i] != that.array[that.start + i]) { return false; } } return true; } return super.equals(object); } @Override public int hashCode() { int result = 1; for (int i = start; i < end; i++) { result = 31 * result + Bytes.hashCode(array[i]); } return result; } @Override public String toString() { StringBuilder builder = new StringBuilder(size() * 5); builder.append('[').append(array[start]); for (int i = start + 1; i < end; i++) { builder.append(", ").append(array[i]); } return builder.append(']').toString(); } byte[] toByteArray() { return Arrays.copyOfRange(array, start, end); } private static final long serialVersionUID = 0; } /** * Reverses the elements of {@code array}. This is equivalent to {@code * Collections.reverse(Bytes.asList(array))}, but is likely to be more efficient. * * @since 23.1 */ public static void reverse(byte[] array) { checkNotNull(array); reverse(array, 0, array.length); } /** * Reverses the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex} * exclusive. This is equivalent to {@code * Collections.reverse(Bytes.asList(array).subList(fromIndex, toIndex))}, but is likely to be more * efficient. * * @throws IndexOutOfBoundsException if {@code fromIndex < 0}, {@code toIndex > array.length}, or * {@code toIndex > fromIndex} * @since 23.1 */ public static void reverse(byte[] array, int fromIndex, int toIndex) { checkNotNull(array); checkPositionIndexes(fromIndex, toIndex, array.length); for (int i = fromIndex, j = toIndex - 1; i < j; i++, j--) { byte tmp = array[i]; array[i] = array[j]; array[j] = tmp; } } }





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