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package org.bitcoinj.core;
import java.io.IOException;
import java.io.InputStream;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.OutputStream;
import java.io.Serializable;
import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import java.nio.charset.UnsupportedCharsetException;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
/**
* Immutable sequence of bytes. Provides conversions to and from {@code byte[]}, {@link
* java.lang.String}, {@link ByteBuffer}, {@link InputStream}, {@link OutputStream}.
*
* Like {@link String}, the contents of a {@link ByteString} can never be observed to change, not
* even in the presence of a data race or incorrect API usage in the client code.
*
* @author [email protected] Bob Lee
* @author [email protected] Kenton Varda
* @author [email protected] Carl Haverl
* @author [email protected] Martin Buchholz
*/
public abstract class ByteString implements Iterable, Serializable {
/**
* When two strings to be concatenated have a combined length shorter than this, we just copy
* their bytes on {@link #concat(ByteString)}. The trade-off is copy size versus the overhead of
* creating tree nodes in {@link RopeByteString}.
*/
static final int CONCATENATE_BY_COPY_SIZE = 128;
/**
* When copying an InputStream into a ByteString with .readFrom(), the chunks in the underlying
* rope start at 256 bytes, but double each iteration up to 8192 bytes.
*/
static final int MIN_READ_FROM_CHUNK_SIZE = 0x100; // 256b
static final int MAX_READ_FROM_CHUNK_SIZE = 0x2000; // 8k
public static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
/** Empty {@code ByteString}. */
public static final ByteString EMPTY = new LiteralByteString(EMPTY_BYTE_ARRAY);
/**
* An interface to efficiently copy {@code byte[]}.
*
* One of the noticeable costs of copying a byte[] into a new array using {@code
* System.arraycopy} is nullification of a new buffer before the copy. It has been shown the
* Hotspot VM is capable to intrisicfy {@code Arrays.copyOfRange} operation to avoid this
* expensive nullification and provide substantial performance gain. Unfortunately this does not
* hold on Android runtimes and could make the copy slightly slower due to additional code in the
* {@code Arrays.copyOfRange}. Thus we provide two different implementation for array copier for
* Hotspot and Android runtimes.
*/
private interface ByteArrayCopier {
/** Copies the specified range of the specified array into a new array */
byte[] copyFrom(byte[] bytes, int offset, int size);
}
/** Implementation of {@code ByteArrayCopier} which uses {@link System#arraycopy}. */
private static final class SystemByteArrayCopier implements ByteArrayCopier {
@Override
public byte[] copyFrom(byte[] bytes, int offset, int size) {
byte[] copy = new byte[size];
System.arraycopy(bytes, offset, copy, 0, size);
return copy;
}
}
/** Implementation of {@code ByteArrayCopier} which uses {@link Arrays#copyOfRange}. */
private static final class ArraysByteArrayCopier implements ByteArrayCopier {
@Override
public byte[] copyFrom(byte[] bytes, int offset, int size) {
return Arrays.copyOfRange(bytes, offset, offset + size);
}
}
private static final ByteArrayCopier byteArrayCopier;
static {
byteArrayCopier = new ArraysByteArrayCopier();
}
/**
* Cached hash value. Intentionally accessed via a data race, which is safe because of the Java
* Memory Model's "no out-of-thin-air values" guarantees for ints. A value of 0 implies that the
* hash has not been set.
*/
private int hash = 0;
// This constructor is here to prevent subclassing outside of this package,
ByteString() {}
/**
* Gets the byte at the given index. This method should be used only for random access to
* individual bytes. To access bytes sequentially, use the {@link ByteIterator} returned by {@link
* #iterator()}, and call {@link #substring(int, int)} first if necessary.
*
* @param index index of byte
* @return the value
* @throws IndexOutOfBoundsException {@code index < 0 or index >= size}
*/
public abstract byte byteAt(int index);
/**
* Gets the byte at the given index, assumes bounds checking has already been performed.
*
* @param index index of byte
* @return the value
* @throws IndexOutOfBoundsException {@code index < 0 or index >= size}
*/
abstract byte internalByteAt(int index);
/**
* Return a {@link ByteString.ByteIterator} over the bytes in the ByteString. To avoid
* auto-boxing, you may get the iterator manually and call {@link ByteIterator#nextByte()}.
*
* @return the iterator
*/
@Override
public ByteIterator iterator() {
return new AbstractByteIterator() {
private int position = 0;
private final int limit = size();
@Override
public boolean hasNext() {
return position < limit;
}
@Override
public byte nextByte() {
int currentPos = position;
if (currentPos >= limit) {
throw new NoSuchElementException();
}
position = currentPos + 1;
return internalByteAt(currentPos);
}
};
}
/**
* This interface extends {@code Iterator}, so that we can return an unboxed {@code byte}.
*/
public interface ByteIterator extends Iterator {
/**
* An alternative to {@link Iterator#next()} that returns an unboxed primitive {@code byte}.
*
* @return the next {@code byte} in the iteration
* @throws NoSuchElementException if the iteration has no more elements
*/
byte nextByte();
}
abstract static class AbstractByteIterator implements ByteIterator {
@Override
public final Byte next() {
// Boxing calls Byte.valueOf(byte), which does not instantiate.
return nextByte();
}
@Override
public final void remove() {
throw new UnsupportedOperationException();
}
}
/**
* Gets the number of bytes.
*
* @return size in bytes
*/
public abstract int size();
/**
* Returns {@code true} if the size is {@code 0}, {@code false} otherwise.
*
* @return true if this is zero bytes long
*/
public final boolean isEmpty() {
return size() == 0;
}
// =================================================================
// Comparison
private static final int UNSIGNED_BYTE_MASK = 0xFF;
/**
* Returns the value of the given byte as an integer, interpreting the byte as an unsigned value.
* That is, returns {@code value + 256} if {@code value} is negative; {@code value} itself
* otherwise.
*
* Note: This code was copied from {@link com.google.common.primitives.UnsignedBytes#toInt}, as
* Guava libraries cannot be used in the {@code com.google.protobuf} package.
*/
private static int toInt(byte value) {
return value & UNSIGNED_BYTE_MASK;
}
/**
* Compares two {@link ByteString}s lexicographically, treating their contents as unsigned byte
* values between 0 and 255 (inclusive).
*
*
For example, {@code (byte) -1} is considered to be greater than {@code (byte) 1} because it
* is interpreted as an unsigned value, {@code 255}.
*/
private static final Comparator UNSIGNED_LEXICOGRAPHICAL_COMPARATOR =
new Comparator() {
@Override
public int compare(ByteString former, ByteString latter) {
ByteIterator formerBytes = former.iterator();
ByteIterator latterBytes = latter.iterator();
while (formerBytes.hasNext() && latterBytes.hasNext()) {
// Note: This code was copied from com.google.common.primitives.UnsignedBytes#compare,
// as Guava libraries cannot be used in the {@code com.google.protobuf} package.
int result =
Integer.compare(toInt(formerBytes.nextByte()), toInt(latterBytes.nextByte()));
if (result != 0) {
return result;
}
}
return Integer.compare(former.size(), latter.size());
}
};
/**
* Returns a {@link Comparator} which compares {@link ByteString}-s lexicographically
* as sequences of unsigned bytes (i.e. values between 0 and 255, inclusive).
*
* For example, {@code (byte) -1} is considered to be greater than {@code (byte) 1} because it
* is interpreted as an unsigned value, {@code 255}:
*
*
* - {@code `-1` -> 0b11111111 (two's complement) -> 255}
*
- {@code `1` -> 0b00000001 -> 1}
*
*/
public static Comparator unsignedLexicographicalComparator() {
return UNSIGNED_LEXICOGRAPHICAL_COMPARATOR;
}
// =================================================================
// ByteString -> substring
/**
* Return the substring from {@code beginIndex}, inclusive, to the end of the string.
*
* @param beginIndex start at this index
* @return substring sharing underlying data
* @throws IndexOutOfBoundsException if {@code beginIndex < 0} or {@code beginIndex > size()}.
*/
public final ByteString substring(int beginIndex) {
return substring(beginIndex, size());
}
/**
* Return the substring from {@code beginIndex}, inclusive, to {@code endIndex}, exclusive.
*
* @param beginIndex start at this index
* @param endIndex the last character is the one before this index
* @return substring sharing underlying data
* @throws IndexOutOfBoundsException if {@code beginIndex < 0}, {@code endIndex > size()}, or
* {@code beginIndex > endIndex}.
*/
public abstract ByteString substring(int beginIndex, int endIndex);
/**
* Tests if this bytestring starts with the specified prefix. Similar to {@link
* String#startsWith(String)}
*
* @param prefix the prefix.
* @return true if the byte sequence represented by the argument is a prefix of the
* byte sequence represented by this string; false otherwise.
*/
public final boolean startsWith(ByteString prefix) {
return size() >= prefix.size() && substring(0, prefix.size()).equals(prefix);
}
/**
* Tests if this bytestring ends with the specified suffix. Similar to {@link
* String#endsWith(String)}
*
* @param suffix the suffix.
* @return true if the byte sequence represented by the argument is a suffix of the
* byte sequence represented by this string; false otherwise.
*/
public final boolean endsWith(ByteString suffix) {
return size() >= suffix.size() && substring(size() - suffix.size()).equals(suffix);
}
// =================================================================
// byte[] -> ByteString
/**
* Copies the given bytes into a {@code ByteString}.
*
* @param bytes source array
* @param offset offset in source array
* @param size number of bytes to copy
* @return new {@code ByteString}
* @throws IndexOutOfBoundsException if {@code offset} or {@code size} are out of bounds
*/
public static ByteString copyFrom(byte[] bytes, int offset, int size) {
checkRange(offset, offset + size, bytes.length);
return new LiteralByteString(byteArrayCopier.copyFrom(bytes, offset, size));
}
/**
* Copies the given bytes into a {@code ByteString}.
*
* @param bytes to copy
* @return new {@code ByteString}
*/
public static ByteString copyFrom(byte[] bytes) {
return copyFrom(bytes, 0, bytes.length);
}
/**
* Wraps the given bytes into a {@code ByteString}. Intended for internal only usage to force a
* classload of ByteString before LiteralByteString.
*/
static ByteString wrap(byte[] bytes) {
// TODO(dweis): Return EMPTY when bytes are empty to reduce allocations?
return new LiteralByteString(bytes);
}
/**
* Wraps the given bytes into a {@code ByteString}. Intended for internal only usage to force a
* classload of ByteString before BoundedByteString and LiteralByteString.
*/
static ByteString wrap(byte[] bytes, int offset, int length) {
return new BoundedByteString(bytes, offset, length);
}
/**
* Copies the next {@code size} bytes from a {@code java.nio.ByteBuffer} into a {@code
* ByteString}.
*
* @param bytes source buffer
* @param size number of bytes to copy
* @return new {@code ByteString}
* @throws IndexOutOfBoundsException if {@code size > bytes.remaining()}
*/
public static ByteString copyFrom(ByteBuffer bytes, int size) {
checkRange(0, size, bytes.remaining());
byte[] copy = new byte[size];
bytes.get(copy);
return new LiteralByteString(copy);
}
/**
* Copies the remaining bytes from a {@code java.nio.ByteBuffer} into a {@code ByteString}.
*
* @param bytes sourceBuffer
* @return new {@code ByteString}
*/
public static ByteString copyFrom(ByteBuffer bytes) {
return copyFrom(bytes, bytes.remaining());
}
/**
* Encodes {@code text} into a sequence of bytes using the named charset and returns the result as
* a {@code ByteString}.
*
* @param text source string
* @param charsetName encoding to use
* @return new {@code ByteString}
* @throws UnsupportedEncodingException if the encoding isn't found
*/
public static ByteString copyFrom(String text, String charsetName)
throws UnsupportedEncodingException {
return new LiteralByteString(text.getBytes(charsetName));
}
/**
* Encodes {@code text} into a sequence of bytes using the named charset and returns the result as
* a {@code ByteString}.
*
* @param text source string
* @param charset encode using this charset
* @return new {@code ByteString}
*/
public static ByteString copyFrom(String text, Charset charset) {
return new LiteralByteString(text.getBytes(charset));
}
/**
* Blocks until a chunk of the given size can be made from the stream, or EOF is reached. Calls
* read() repeatedly in case the given stream implementation doesn't completely fill the given
* buffer in one read() call.
*
* @return A chunk of the desired size, or else a chunk as large as was available when end of
* stream was reached. Returns null if the given stream had no more data in it.
*/
private static ByteString readChunk(InputStream in, final int chunkSize) throws IOException {
final byte[] buf = new byte[chunkSize];
int bytesRead = 0;
while (bytesRead < chunkSize) {
final int count = in.read(buf, bytesRead, chunkSize - bytesRead);
if (count == -1) {
break;
}
bytesRead += count;
}
if (bytesRead == 0) {
return null;
}
// Always make a copy since InputStream could steal a reference to buf.
return ByteString.copyFrom(buf, 0, bytesRead);
}
// =================================================================
// ByteString -> byte[]
/**
* Copies bytes into a buffer at the given offset.
*
* To copy a subset of bytes, you call this method on the return value of {@link
* #substring(int, int)}. Example: {@code byteString.substring(start, end).copyTo(target, offset)}
*
* @param target buffer to copy into
* @param offset in the target buffer
* @throws IndexOutOfBoundsException if the offset is negative or too large
*/
public void copyTo(byte[] target, int offset) {
copyTo(target, 0, offset, size());
}
/**
* Copies bytes into a buffer.
*
* @param target buffer to copy into
* @param sourceOffset offset within these bytes
* @param targetOffset offset within the target buffer
* @param numberToCopy number of bytes to copy
* @throws IndexOutOfBoundsException if an offset or size is negative or too large
* @deprecated Instead, call {@code byteString.substring(sourceOffset, sourceOffset +
* numberToCopy).copyTo(target, targetOffset)}
*/
@Deprecated
public final void copyTo(byte[] target, int sourceOffset, int targetOffset, int numberToCopy) {
checkRange(sourceOffset, sourceOffset + numberToCopy, size());
checkRange(targetOffset, targetOffset + numberToCopy, target.length);
if (numberToCopy > 0) {
copyToInternal(target, sourceOffset, targetOffset, numberToCopy);
}
}
/**
* Internal (package private) implementation of {@link #copyTo(byte[],int,int,int)}. It assumes
* that all error checking has already been performed and that {@code numberToCopy > 0}.
*/
protected abstract void copyToInternal(
byte[] target, int sourceOffset, int targetOffset, int numberToCopy);
/**
* Copies bytes into a ByteBuffer.
*
*
To copy a subset of bytes, you call this method on the return value of {@link
* #substring(int, int)}. Example: {@code byteString.substring(start, end).copyTo(target)}
*
* @param target ByteBuffer to copy into.
* @throws java.nio.ReadOnlyBufferException if the {@code target} is read-only
* @throws java.nio.BufferOverflowException if the {@code target}'s remaining() space is not large
* enough to hold the data.
*/
public abstract void copyTo(ByteBuffer target);
/**
* Copies bytes to a {@code byte[]}.
*
* @return copied bytes
*/
public final byte[] toByteArray() {
final int size = size();
if (size == 0) {
return EMPTY_BYTE_ARRAY;
}
byte[] result = new byte[size];
copyToInternal(result, 0, 0, size);
return result;
}
/**
* Writes a copy of the contents of this byte string to the specified output stream argument.
*
* @param out the output stream to which to write the data.
* @throws IOException if an I/O error occurs.
*/
public abstract void writeTo(OutputStream out) throws IOException;
/**
* Writes a specified part of this byte string to an output stream.
*
* @param out the output stream to which to write the data.
* @param sourceOffset offset within these bytes
* @param numberToWrite number of bytes to write
* @throws IOException if an I/O error occurs.
* @throws IndexOutOfBoundsException if an offset or size is negative or too large
*/
final void writeTo(OutputStream out, int sourceOffset, int numberToWrite) throws IOException {
checkRange(sourceOffset, sourceOffset + numberToWrite, size());
if (numberToWrite > 0) {
writeToInternal(out, sourceOffset, numberToWrite);
}
}
/**
* Internal version of {@link #writeTo(OutputStream,int,int)} that assumes all error checking has
* already been done.
*/
abstract void writeToInternal(OutputStream out, int sourceOffset, int numberToWrite)
throws IOException;
/**
* Constructs a read-only {@code java.nio.ByteBuffer} whose content is equal to the contents of
* this byte string. The result uses the same backing array as the byte string, if possible.
*
* @return wrapped bytes
*/
public abstract ByteBuffer asReadOnlyByteBuffer();
/**
* Constructs a list of read-only {@code java.nio.ByteBuffer} objects such that the concatenation
* of their contents is equal to the contents of this byte string. The result uses the same
* backing arrays as the byte string.
*
*
By returning a list, implementations of this method may be able to avoid copying even when
* there are multiple backing arrays.
*
* @return a list of wrapped bytes
*/
public abstract List asReadOnlyByteBufferList();
/**
* Constructs a new {@code String} by decoding the bytes using the specified charset.
*
* @param charsetName encode using this charset
* @return new string
* @throws UnsupportedEncodingException if charset isn't recognized
*/
public final String toString(String charsetName) throws UnsupportedEncodingException {
try {
return toString(Charset.forName(charsetName));
} catch (UnsupportedCharsetException e) {
UnsupportedEncodingException exception = new UnsupportedEncodingException(charsetName);
exception.initCause(e);
throw exception;
}
}
/**
* Constructs a new {@code String} by decoding the bytes using the specified charset. Returns the
* same empty String if empty.
*
* @param charset encode using this charset
* @return new string
*/
public final String toString(Charset charset) {
return size() == 0 ? "" : toStringInternal(charset);
}
/**
* Constructs a new {@code String} by decoding the bytes using the specified charset.
*
* @param charset encode using this charset
* @return new string
*/
protected abstract String toStringInternal(Charset charset);
// =================================================================
// equals() and hashCode()
@Override
public abstract boolean equals(Object o);
/** Base class for leaf {@link ByteString}s (i.e. non-ropes). */
abstract static class LeafByteString extends ByteString {
@Override
protected final int getTreeDepth() {
return 0;
}
@Override
protected final boolean isBalanced() {
return true;
}
/**
* Check equality of the substring of given length of this object starting at zero with another
* {@code ByteString} substring starting at offset.
*
* @param other what to compare a substring in
* @param offset offset into other
* @param length number of bytes to compare
* @return true for equality of substrings, else false.
*/
abstract boolean equalsRange(ByteString other, int offset, int length);
}
// =================================================================
// Methods {@link RopeByteString} needs on instances, which aren't part of the
// public API.
/**
* Return the depth of the tree representing this {@code ByteString}, if any, whose root is this
* node. If this is a leaf node, return 0.
*
* @return tree depth or zero
*/
protected abstract int getTreeDepth();
/**
* Return {@code true} if this ByteString is literal (a leaf node) or a flat-enough tree in the
* sense of RopeByteString.
*
* @return true if the tree is flat enough
*/
protected abstract boolean isBalanced();
/**
* Return the cached hash code if available.
*
* @return value of cached hash code or 0 if not computed yet
*/
protected final int peekCachedHashCode() {
return hash;
}
/**
* Checks that the given index falls within the specified array size.
*
* @param index the index position to be tested
* @param size the length of the array
* @throws IndexOutOfBoundsException if the index does not fall within the array.
*/
static void checkIndex(int index, int size) {
if ((index | (size - (index + 1))) < 0) {
if (index < 0) {
throw new ArrayIndexOutOfBoundsException("Index < 0: " + index);
}
throw new ArrayIndexOutOfBoundsException("Index > length: " + index + ", " + size);
}
}
/**
* Checks that the given range falls within the bounds of an array
*
* @param startIndex the start index of the range (inclusive)
* @param endIndex the end index of the range (exclusive)
* @param size the size of the array.
* @return the length of the range.
* @throws IndexOutOfBoundsException some or all of the range falls outside of the array.
*/
static int checkRange(int startIndex, int endIndex, int size) {
final int length = endIndex - startIndex;
if ((startIndex | endIndex | length | (size - endIndex)) < 0) {
if (startIndex < 0) {
throw new IndexOutOfBoundsException("Beginning index: " + startIndex + " < 0");
}
if (endIndex < startIndex) {
throw new IndexOutOfBoundsException(
"Beginning index larger than ending index: " + startIndex + ", " + endIndex);
}
// endIndex >= size
throw new IndexOutOfBoundsException("End index: " + endIndex + " >= " + size);
}
return length;
}
/**
* This class implements a com.google.protobuf.ByteString backed by a single array of
* bytes, contiguous in memory. It supports substring by pointing to only a sub-range of the
* underlying byte array, meaning that a substring will reference the full byte-array of the
* string it's made from, exactly as with {@link String}.
*
* @author [email protected] (Carl Haverl)
*/
// Keep this class private to avoid deadlocks in classloading across threads as ByteString's
// static initializer loads LiteralByteString and another thread loads LiteralByteString.
private static class LiteralByteString extends ByteString.LeafByteString {
private static final long serialVersionUID = 1L;
protected final byte[] bytes;
/**
* Creates a {@code LiteralByteString} backed by the given array, without copying.
*
* @param bytes array to wrap
*/
LiteralByteString(byte[] bytes) {
if (bytes == null) {
throw new NullPointerException();
}
this.bytes = bytes;
}
@Override
public byte byteAt(int index) {
// Unlike most methods in this class, this one is a direct implementation
// ignoring the potential offset because we need to do range-checking in the
// substring case anyway.
return bytes[index];
}
@Override
byte internalByteAt(int index) {
return bytes[index];
}
@Override
public int size() {
return bytes.length;
}
// =================================================================
// ByteString -> substring
@Override
public final ByteString substring(int beginIndex, int endIndex) {
final int length = checkRange(beginIndex, endIndex, size());
if (length == 0) {
return ByteString.EMPTY;
}
return new BoundedByteString(bytes, getOffsetIntoBytes() + beginIndex, length);
}
// =================================================================
// ByteString -> byte[]
@Override
protected void copyToInternal(
byte[] target, int sourceOffset, int targetOffset, int numberToCopy) {
// Optimized form, not for subclasses, since we don't call
// getOffsetIntoBytes() or check the 'numberToCopy' parameter.
// TODO(nathanmittler): Is not calling getOffsetIntoBytes really saving that much?
System.arraycopy(bytes, sourceOffset, target, targetOffset, numberToCopy);
}
@Override
public final void copyTo(ByteBuffer target) {
target.put(bytes, getOffsetIntoBytes(), size()); // Copies bytes
}
@Override
public final ByteBuffer asReadOnlyByteBuffer() {
return ByteBuffer.wrap(bytes, getOffsetIntoBytes(), size()).asReadOnlyBuffer();
}
@Override
public final List asReadOnlyByteBufferList() {
return Collections.singletonList(asReadOnlyByteBuffer());
}
@Override
public final void writeTo(OutputStream outputStream) throws IOException {
outputStream.write(toByteArray());
}
@Override
final void writeToInternal(OutputStream outputStream, int sourceOffset, int numberToWrite)
throws IOException {
outputStream.write(bytes, getOffsetIntoBytes() + sourceOffset, numberToWrite);
}
@Override
protected final String toStringInternal(Charset charset) {
return new String(bytes, getOffsetIntoBytes(), size(), charset);
}
// =================================================================
// equals() and hashCode()
@Override
public final boolean equals(Object other) {
if (other == this) {
return true;
}
if (!(other instanceof ByteString)) {
return false;
}
if (size() != ((ByteString) other).size()) {
return false;
}
if (size() == 0) {
return true;
}
if (other instanceof LiteralByteString) {
LiteralByteString otherAsLiteral = (LiteralByteString) other;
// If we know the hash codes and they are not equal, we know the byte
// strings are not equal.
int thisHash = peekCachedHashCode();
int thatHash = otherAsLiteral.peekCachedHashCode();
if (thisHash != 0 && thatHash != 0 && thisHash != thatHash) {
return false;
}
return equalsRange((LiteralByteString) other, 0, size());
} else {
// RopeByteString and NioByteString.
return other.equals(this);
}
}
/**
* Check equality of the substring of given length of this object starting at zero with another
* {@code LiteralByteString} substring starting at offset.
*
* @param other what to compare a substring in
* @param offset offset into other
* @param length number of bytes to compare
* @return true for equality of substrings, else false.
*/
@Override
final boolean equalsRange(ByteString other, int offset, int length) {
if (length > other.size()) {
throw new IllegalArgumentException("Length too large: " + length + size());
}
if (offset + length > other.size()) {
throw new IllegalArgumentException(
"Ran off end of other: " + offset + ", " + length + ", " + other.size());
}
if (other instanceof LiteralByteString) {
LiteralByteString lbsOther = (LiteralByteString) other;
byte[] thisBytes = bytes;
byte[] otherBytes = lbsOther.bytes;
int thisLimit = getOffsetIntoBytes() + length;
for (int thisIndex = getOffsetIntoBytes(),
otherIndex = lbsOther.getOffsetIntoBytes() + offset;
(thisIndex < thisLimit);
++thisIndex, ++otherIndex) {
if (thisBytes[thisIndex] != otherBytes[otherIndex]) {
return false;
}
}
return true;
}
return other.substring(offset, offset + length).equals(substring(0, length));
}
// =================================================================
// Internal methods
/**
* Offset into {@code bytes[]} to use, non-zero for substrings.
*
* @return always 0 for this class
*/
protected int getOffsetIntoBytes() {
return 0;
}
}
/**
* This class is used to represent the substring of a {@link ByteString} over a single byte array.
* In terms of the public API of {@link ByteString}, you end up here by calling {@link
* ByteString#copyFrom(byte[])} followed by {@link ByteString#substring(int, int)}.
*
* This class contains most of the overhead involved in creating a substring from a {@link
* LiteralByteString}. The overhead involves some range-checking and two extra fields.
*
* @author [email protected] (Carl Haverl)
*/
// Keep this class private to avoid deadlocks in classloading across threads as ByteString's
// static initializer loads LiteralByteString and another thread loads BoundedByteString.
private static final class BoundedByteString extends LiteralByteString {
private final int bytesOffset;
private final int bytesLength;
/**
* Creates a {@code BoundedByteString} backed by the sub-range of given array, without copying.
*
* @param bytes array to wrap
* @param offset index to first byte to use in bytes
* @param length number of bytes to use from bytes
* @throws IllegalArgumentException if {@code offset < 0}, {@code length < 0}, or if {@code
* offset + length > bytes.length}.
*/
BoundedByteString(byte[] bytes, int offset, int length) {
super(bytes);
checkRange(offset, offset + length, bytes.length);
this.bytesOffset = offset;
this.bytesLength = length;
}
/**
* Gets the byte at the given index. Throws {@link ArrayIndexOutOfBoundsException} for
* backwards-compatibility reasons although it would more properly be {@link
* IndexOutOfBoundsException}.
*
* @param index index of byte
* @return the value
* @throws ArrayIndexOutOfBoundsException {@code index} is < 0 or >= size
*/
@Override
public byte byteAt(int index) {
// We must check the index ourselves as we cannot rely on Java array index
// checking for substrings.
checkIndex(index, size());
return bytes[bytesOffset + index];
}
@Override
byte internalByteAt(int index) {
return bytes[bytesOffset + index];
}
@Override
public int size() {
return bytesLength;
}
@Override
protected int getOffsetIntoBytes() {
return bytesOffset;
}
// =================================================================
// ByteString -> byte[]
@Override
protected void copyToInternal(
byte[] target, int sourceOffset, int targetOffset, int numberToCopy) {
System.arraycopy(
bytes, getOffsetIntoBytes() + sourceOffset, target, targetOffset, numberToCopy);
}
// =================================================================
// Serializable
private static final long serialVersionUID = 1L;
Object writeReplace() {
return ByteString.wrap(toByteArray());
}
private void readObject(@SuppressWarnings("unused") ObjectInputStream in) throws IOException {
throw new InvalidObjectException(
"BoundedByteStream instances are not to be serialized directly");
}
}
}