com.google.common.primitives.Bytes Maven / Gradle / Ivy
/*
* 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;
/**
* 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()}.
*
* @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
* java.util.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)
? copyOf(array, minLength + padding)
: array;
}
// Arrays.copyOf() requires Java 6
private static byte[] copyOf(byte[] original, int length) {
byte[] copy = new byte[length];
System.arraycopy(original, 0, copy, 0, Math.min(original.length, length));
return copy;
}
/**
* 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(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() {
// Arrays.copyOfRange() is not available under GWT
int size = size();
byte[] result = new byte[size];
System.arraycopy(array, start, result, 0, size);
return result;
}
private static final long serialVersionUID = 0;
}
}