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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 javax.annotation.CheckReturnValue; import javax.annotation.Nullable; /** * Static utility methods pertaining to {@code byte} primitives, that are not * already found in either {@link Byte} or {@link Arrays}, <i>and interpret * bytes as neither signed nor unsigned</i>. The methods which specifically * treat bytes as signed or unsigned are found in {@link SignedBytes} and {@link * UnsignedBytes}. * * <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? @CheckReturnValue @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. * * <p>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}. * * <p>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<Byte>} before 12.0) */ public static byte[] toArray(Collection<? extends Number> 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}. * * <p>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<Byte> asList(byte... backingArray) { if (backingArray.length == 0) { return Collections.emptyList(); } return new ByteArrayAsList(backingArray); } @GwtCompatible private static class ByteArrayAsList extends AbstractList<Byte> 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<Byte> 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() { // 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; } }