// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// http://code.google.com/p/protobuf/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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package com.google.protobuf;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
/**
* Immutable sequence of bytes. Substring is supported by sharing the reference
* to the immutable underlying bytes, as with {@link String}. Concatenation is
* likewise supported without copying (long strings) by building a tree of
* pieces in {@link RopeByteString}.
* <p>
* 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 crazybob@google.com Bob Lee
* @author kenton@google.com Kenton Varda
* @author carlanton@google.com Carl Haverl
* @author martinrb@google.com Martin Buchholz
*/
public abstract class ByteString implements Iterable<Byte> {
/**
* 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
/**
* Empty {@code ByteString}.
*/
public static final ByteString EMPTY = new LiteralByteString(new byte[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 ArrayIndexOutOfBoundsException {@code index} is < 0 or >= size
*/
public abstract byte byteAt(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
*/
public abstract ByteIterator iterator();
/**
* This interface extends {@code Iterator<Byte>}, so that we can return an
* unboxed {@code byte}.
*/
public interface ByteIterator extends Iterator<Byte> {
/**
* 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();
}
/**
* 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 boolean isEmpty() {
return size() == 0;
}
// =================================================================
// 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 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 <code>true</code> if the byte sequence represented by the
* argument is a prefix of the byte sequence represented by
* this string; <code>false</code> otherwise.
*/
public 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 <code>true</code> if the byte sequence represented by the
* argument is a suffix of the byte sequence represented by
* this string; <code>false</code> otherwise.
*/
public 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}
*/
public static ByteString copyFrom(byte[] bytes, int offset, int size) {
byte[] copy = new byte[size];
System.arraycopy(bytes, offset, copy, 0, size);
return new LiteralByteString(copy);
}
/**
* 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);
}
/**
* 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}
*/
public static ByteString copyFrom(ByteBuffer bytes, int size) {
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 UTF-8 bytes and returns the
* result as a {@code ByteString}.
*
* @param text source string
* @return new {@code ByteString}
*/
public static ByteString copyFromUtf8(String text) {
try {
return new LiteralByteString(text.getBytes("UTF-8"));
} catch (UnsupportedEncodingException e) {
throw new RuntimeException("UTF-8 not supported?", e);
}
}
// =================================================================
// InputStream -> ByteString
/**
* Completely reads the given stream's bytes into a
* {@code ByteString}, blocking if necessary until all bytes are
* read through to the end of the stream.
*
* <b>Performance notes:</b> The returned {@code ByteString} is an
* immutable tree of byte arrays ("chunks") of the stream data. The
* first chunk is small, with subsequent chunks each being double
* the size, up to 8K. If the caller knows the precise length of
* the stream and wishes to avoid all unnecessary copies and
* allocations, consider using the two-argument version of this
* method, below.
*
* @param streamToDrain The source stream, which is read completely
* but not closed.
* @return A new {@code ByteString} which is made up of chunks of
* various sizes, depending on the behavior of the underlying
* stream.
* @throws IOException IOException is thrown if there is a problem
* reading the underlying stream.
*/
public static ByteString readFrom(InputStream streamToDrain)
throws IOException {
return readFrom(
streamToDrain, MIN_READ_FROM_CHUNK_SIZE, MAX_READ_FROM_CHUNK_SIZE);
}
/**
* Completely reads the given stream's bytes into a
* {@code ByteString}, blocking if necessary until all bytes are
* read through to the end of the stream.
*
* <b>Performance notes:</b> The returned {@code ByteString} is an
* immutable tree of byte arrays ("chunks") of the stream data. The
* chunkSize parameter sets the size of these byte arrays. In
* particular, if the chunkSize is precisely the same as the length
* of the stream, unnecessary allocations and copies will be
* avoided. Otherwise, the chunks will be of the given size, except
* for the last chunk, which will be resized (via a reallocation and
* copy) to contain the remainder of the stream.
*
* @param streamToDrain The source stream, which is read completely
* but not closed.
* @param chunkSize The size of the chunks in which to read the
* stream.
* @return A new {@code ByteString} which is made up of chunks of
* the given size.
* @throws IOException IOException is thrown if there is a problem
* reading the underlying stream.
*/
public static ByteString readFrom(InputStream streamToDrain, int chunkSize)
throws IOException {
return readFrom(streamToDrain, chunkSize, chunkSize);
}
// Helper method that takes the chunk size range as a parameter.
public static ByteString readFrom(InputStream streamToDrain, int minChunkSize,
int maxChunkSize) throws IOException {
Collection<ByteString> results = new ArrayList<ByteString>();
// copy the inbound bytes into a list of chunks; the chunk size
// grows exponentially to support both short and long streams.
int chunkSize = minChunkSize;
while (true) {
ByteString chunk = readChunk(streamToDrain, chunkSize);
if (chunk == null) {
break;
}
results.add(chunk);
chunkSize = Math.min(chunkSize * 2, maxChunkSize);
}
return ByteString.copyFrom(results);
}
/**
* 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;
} else {
return ByteString.copyFrom(buf, 0, bytesRead);
}
}
// =================================================================
// Multiple ByteStrings -> One ByteString
/**
* Concatenate the given {@code ByteString} to this one. Short concatenations,
* of total size smaller than {@link ByteString#CONCATENATE_BY_COPY_SIZE}, are
* produced by copying the underlying bytes (as per Rope.java, <a
* href="http://www.cs.ubc.ca/local/reading/proceedings/spe91-95/spe/vol25/issue12/spe986.pdf">
* BAP95 </a>. In general, the concatenate involves no copying.
*
* @param other string to concatenate
* @return a new {@code ByteString} instance
*/
public ByteString concat(ByteString other) {
int thisSize = size();
int otherSize = other.size();
if ((long) thisSize + otherSize >= Integer.MAX_VALUE) {
throw new IllegalArgumentException("ByteString would be too long: " +
thisSize + "+" + otherSize);
}
return RopeByteString.concatenate(this, other);
}
/**
* Concatenates all byte strings in the iterable and returns the result.
* This is designed to run in O(list size), not O(total bytes).
*
* <p>The returned {@code ByteString} is not necessarily a unique object.
* If the list is empty, the returned object is the singleton empty
* {@code ByteString}. If the list has only one element, that
* {@code ByteString} will be returned without copying.
*
* @param byteStrings strings to be concatenated
* @return new {@code ByteString}
*/
public static ByteString copyFrom(Iterable<ByteString> byteStrings) {
Collection<ByteString> collection;
if (!(byteStrings instanceof Collection)) {
collection = new ArrayList<ByteString>();
for (ByteString byteString : byteStrings) {
collection.add(byteString);
}
} else {
collection = (Collection<ByteString>) byteStrings;
}
ByteString result;
if (collection.isEmpty()) {
result = EMPTY;
} else {
result = balancedConcat(collection.iterator(), collection.size());
}
return result;
}
// Internal function used by copyFrom(Iterable<ByteString>).
// Create a balanced concatenation of the next "length" elements from the
// iterable.
private static ByteString balancedConcat(Iterator<ByteString> iterator,
int length) {
assert length >= 1;
ByteString result;
if (length == 1) {
result = iterator.next();
} else {
int halfLength = length >>> 1;
ByteString left = balancedConcat(iterator, halfLength);
ByteString right = balancedConcat(iterator, length - halfLength);
result = left.concat(right);
}
return result;
}
// =================================================================
// ByteString -> byte[]
/**
* Copies bytes into a buffer at the given 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
*/
public void copyTo(byte[] target, int sourceOffset, int targetOffset,
int numberToCopy) {
if (sourceOffset < 0) {
throw new IndexOutOfBoundsException("Source offset < 0: " + sourceOffset);
}
if (targetOffset < 0) {
throw new IndexOutOfBoundsException("Target offset < 0: " + targetOffset);
}
if (numberToCopy < 0) {
throw new IndexOutOfBoundsException("Length < 0: " + numberToCopy);
}
if (sourceOffset + numberToCopy > size()) {
throw new IndexOutOfBoundsException(
"Source end offset < 0: " + (sourceOffset + numberToCopy));
}
if (targetOffset + numberToCopy > target.length) {
throw new IndexOutOfBoundsException(
"Target end offset < 0: " + (targetOffset + numberToCopy));
}
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.
*
* @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 byte[] toByteArray() {
int size = size();
if (size == 0) {
return Internal.EMPTY_BYTE_ARRAY;
}
byte[] result = new byte[size];
copyToInternal(result, 0, 0, size);
return result;
}
/**
* Writes the complete 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
*/
void writeTo(OutputStream out, int sourceOffset, int numberToWrite)
throws IOException {
if (sourceOffset < 0) {
throw new IndexOutOfBoundsException("Source offset < 0: " + sourceOffset);
}
if (numberToWrite < 0) {
throw new IndexOutOfBoundsException("Length < 0: " + numberToWrite);
}
if (sourceOffset + numberToWrite > size()) {
throw new IndexOutOfBoundsException(
"Source end offset exceeded: " + (sourceOffset + numberToWrite));
}
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.
* <p>
* 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<ByteBuffer> 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 abstract String toString(String charsetName)
throws UnsupportedEncodingException;
// =================================================================
// UTF-8 decoding
/**
* Constructs a new {@code String} by decoding the bytes as UTF-8.
*
* @return new string using UTF-8 encoding
*/
public String toStringUtf8() {
try {
return toString("UTF-8");
} catch (UnsupportedEncodingException e) {
throw new RuntimeException("UTF-8 not supported?", e);
}
}
/**
* Tells whether this {@code ByteString} represents a well-formed UTF-8
* byte sequence, such that the original bytes can be converted to a
* String object and then round tripped back to bytes without loss.
*
* <p>More precisely, returns {@code true} whenever: <pre> {@code
* Arrays.equals(byteString.toByteArray(),
* new String(byteString.toByteArray(), "UTF-8").getBytes("UTF-8"))
* }</pre>
*
* <p>This method returns {@code false} for "overlong" byte sequences,
* as well as for 3-byte sequences that would map to a surrogate
* character, in accordance with the restricted definition of UTF-8
* introduced in Unicode 3.1. Note that the UTF-8 decoder included in
* Oracle's JDK has been modified to also reject "overlong" byte
* sequences, but (as of 2011) still accepts 3-byte surrogate
* character byte sequences.
*
* <p>See the Unicode Standard,</br>
* Table 3-6. <em>UTF-8 Bit Distribution</em>,</br>
* Table 3-7. <em>Well Formed UTF-8 Byte Sequences</em>.
*
* @return whether the bytes in this {@code ByteString} are a
* well-formed UTF-8 byte sequence
*/
public abstract boolean isValidUtf8();
/**
* Tells whether the given byte sequence is a well-formed, malformed, or
* incomplete UTF-8 byte sequence. This method accepts and returns a partial
* state result, allowing the bytes for a complete UTF-8 byte sequence to be
* composed from multiple {@code ByteString} segments.
*
* @param state either {@code 0} (if this is the initial decoding operation)
* or the value returned from a call to a partial decoding method for the
* previous bytes
* @param offset offset of the first byte to check
* @param length number of bytes to check
*
* @return {@code -1} if the partial byte sequence is definitely malformed,
* {@code 0} if it is well-formed (no additional input needed), or, if the
* byte sequence is "incomplete", i.e. apparently terminated in the middle of
* a character, an opaque integer "state" value containing enough information
* to decode the character when passed to a subsequent invocation of a
* partial decoding method.
*/
protected abstract int partialIsValidUtf8(int state, int offset, int length);
// =================================================================
// equals() and hashCode()
@Override
public abstract boolean equals(Object o);
/**
* Return a non-zero hashCode depending only on the sequence of bytes
* in this ByteString.
*
* @return hashCode value for this object
*/
@Override
public abstract int hashCode();
// =================================================================
// Input stream
/**
* Creates an {@code InputStream} which can be used to read the bytes.
* <p>
* The {@link InputStream} returned by this method is guaranteed to be
* completely non-blocking. The method {@link InputStream#available()}
* returns the number of bytes remaining in the stream. The methods
* {@link InputStream#read(byte[]), {@link InputStream#read(byte[],int,int)}
* and {@link InputStream#skip(long)} will read/skip as many bytes as are
* available.
* <p>
* The methods in the returned {@link InputStream} might <b>not</b> be
* thread safe.
*
* @return an input stream that returns the bytes of this byte string.
*/
public abstract InputStream newInput();
/**
* Creates a {@link CodedInputStream} which can be used to read the bytes.
* Using this is often more efficient than creating a {@link CodedInputStream}
* that wraps the result of {@link #newInput()}.
*
* @return stream based on wrapped data
*/
public abstract CodedInputStream newCodedInput();
// =================================================================
// Output stream
/**
* Creates a new {@link Output} with the given initial capacity. Call {@link
* Output#toByteString()} to create the {@code ByteString} instance.
* <p>
* A {@link ByteString.Output} offers the same functionality as a
* {@link ByteArrayOutputStream}, except that it returns a {@link ByteString}
* rather than a {@code byte} array.
*
* @param initialCapacity estimate of number of bytes to be written
* @return {@code OutputStream} for building a {@code ByteString}
*/
public static Output newOutput(int initialCapacity) {
return new Output(initialCapacity);
}
/**
* Creates a new {@link Output}. Call {@link Output#toByteString()} to create
* the {@code ByteString} instance.
* <p>
* A {@link ByteString.Output} offers the same functionality as a
* {@link ByteArrayOutputStream}, except that it returns a {@link ByteString}
* rather than a {@code byte array}.
*
* @return {@code OutputStream} for building a {@code ByteString}
*/
public static Output newOutput() {
return new Output(CONCATENATE_BY_COPY_SIZE);
}
/**
* Outputs to a {@code ByteString} instance. Call {@link #toByteString()} to
* create the {@code ByteString} instance.
*/
public static final class Output extends OutputStream {
// Implementation note.
// The public methods of this class must be synchronized. ByteStrings
// are guaranteed to be immutable. Without some sort of locking, it could
// be possible for one thread to call toByteSring(), while another thread
// is still modifying the underlying byte array.
private static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
// argument passed by user, indicating initial capacity.
private final int initialCapacity;
// ByteStrings to be concatenated to create the result
private final ArrayList<ByteString> flushedBuffers;
// Total number of bytes in the ByteStrings of flushedBuffers
private int flushedBuffersTotalBytes;
// Current buffer to which we are writing
private byte[] buffer;
// Location in buffer[] to which we write the next byte.
private int bufferPos;
/**
* Creates a new ByteString output stream with the specified
* initial capacity.
*
* @param initialCapacity the initial capacity of the output stream.
*/
Output(int initialCapacity) {
if (initialCapacity < 0) {
throw new IllegalArgumentException("Buffer size < 0");
}
this.initialCapacity = initialCapacity;
this.flushedBuffers = new ArrayList<ByteString>();
this.buffer = new byte[initialCapacity];
}
@Override
public synchronized void write(int b) {
if (bufferPos == buffer.length) {
flushFullBuffer(1);
}
buffer[bufferPos++] = (byte)b;
}
@Override
public synchronized void write(byte[] b, int offset, int length) {
if (length <= buffer.length - bufferPos) {
// The bytes can fit into the current buffer.
System.arraycopy(b, offset, buffer, bufferPos, length);
bufferPos += length;
} else {
// Use up the current buffer
int copySize = buffer.length - bufferPos;
System.arraycopy(b, offset, buffer, bufferPos, copySize);
offset += copySize;
length -= copySize;
// Flush the buffer, and get a new buffer at least big enough to cover
// what we still need to output
flushFullBuffer(length);
System.arraycopy(b, offset, buffer, 0 /* count */, length);
bufferPos = length;
}
}
/**
* Creates a byte string. Its size is the current size of this output
* stream and its output has been copied to it.
*
* @return the current contents of this output stream, as a byte string.
*/
public synchronized ByteString toByteString() {
flushLastBuffer();
return ByteString.copyFrom(flushedBuffers);
}
/**
* Implement java.util.Arrays.copyOf() for jdk 1.5.
*/
private byte[] copyArray(byte[] buffer, int length) {
byte[] result = new byte[length];
System.arraycopy(buffer, 0, result, 0, Math.min(buffer.length, length));
return result;
}
/**
* Writes the complete contents of this byte array output stream 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 void writeTo(OutputStream out) throws IOException {
ByteString[] cachedFlushBuffers;
byte[] cachedBuffer;
int cachedBufferPos;
synchronized (this) {
// Copy the information we need into local variables so as to hold
// the lock for as short a time as possible.
cachedFlushBuffers =
flushedBuffers.toArray(new ByteString[flushedBuffers.size()]);
cachedBuffer = buffer;
cachedBufferPos = bufferPos;
}
for (ByteString byteString : cachedFlushBuffers) {
byteString.writeTo(out);
}
out.write(copyArray(cachedBuffer, cachedBufferPos));
}
/**
* Returns the current size of the output stream.
*
* @return the current size of the output stream
*/
public synchronized int size() {
return flushedBuffersTotalBytes + bufferPos;
}
/**
* Resets this stream, so that all currently accumulated output in the
* output stream is discarded. The output stream can be used again,
* reusing the already allocated buffer space.
*/
public synchronized void reset() {
flushedBuffers.clear();
flushedBuffersTotalBytes = 0;
bufferPos = 0;
}
@Override
public String toString() {
return String.format("<ByteString.Output@%s size=%d>",
Integer.toHexString(System.identityHashCode(this)), size());
}
/**
* Internal function used by writers. The current buffer is full, and the
* writer needs a new buffer whose size is at least the specified minimum
* size.
*/
private void flushFullBuffer(int minSize) {
flushedBuffers.add(new LiteralByteString(buffer));
flushedBuffersTotalBytes += buffer.length;
// We want to increase our total capacity by 50%, but as a minimum,
// the new buffer should also at least be >= minSize and
// >= initial Capacity.
int newSize = Math.max(initialCapacity,
Math.max(minSize, flushedBuffersTotalBytes >>> 1));
buffer = new byte[newSize];
bufferPos = 0;
}
/**
* Internal function used by {@link #toByteString()}. The current buffer may
* or may not be full, but it needs to be flushed.
*/
private void flushLastBuffer() {
if (bufferPos < buffer.length) {
if (bufferPos > 0) {
byte[] bufferCopy = copyArray(buffer, bufferPos);
flushedBuffers.add(new LiteralByteString(bufferCopy));
}
// We reuse this buffer for further writes.
} else {
// Buffer is completely full. Huzzah.
flushedBuffers.add(new LiteralByteString(buffer));
// 99% of the time, we're not going to use this OutputStream again.
// We set buffer to an empty byte stream so that we're handling this
// case without wasting space. In the rare case that more writes
// *do* occur, this empty buffer will be flushed and an appropriately
// sized new buffer will be created.
buffer = EMPTY_BYTE_ARRAY;
}
flushedBuffersTotalBytes += bufferPos;
bufferPos = 0;
}
}
/**
* Constructs a new {@code ByteString} builder, which allows you to
* efficiently construct a {@code ByteString} by writing to a {@link
* CodedOutputStream}. Using this is much more efficient than calling {@code
* newOutput()} and wrapping that in a {@code CodedOutputStream}.
*
* <p>This is package-private because it's a somewhat confusing interface.
* Users can call {@link Message#toByteString()} instead of calling this
* directly.
*
* @param size The target byte size of the {@code ByteString}. You must write
* exactly this many bytes before building the result.
* @return the builder
*/
static CodedBuilder newCodedBuilder(int size) {
return new CodedBuilder(size);
}
/** See {@link ByteString#newCodedBuilder(int)}. */
static final class CodedBuilder {
private final CodedOutputStream output;
private final byte[] buffer;
private CodedBuilder(int size) {
buffer = new byte[size];
output = CodedOutputStream.newInstance(buffer);
}
public ByteString build() {
output.checkNoSpaceLeft();
// We can be confident that the CodedOutputStream will not modify the
// underlying bytes anymore because it already wrote all of them. So,
// no need to make a copy.
return new LiteralByteString(buffer);
}
public CodedOutputStream getCodedOutput() {
return output;
}
}
// =================================================================
// 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 {@link 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 abstract int peekCachedHashCode();
/**
* Compute the hash across the value bytes starting with the given hash, and
* return the result. This is used to compute the hash across strings
* represented as a set of pieces by allowing the hash computation to be
* continued from piece to piece.
*
* @param h starting hash value
* @param offset offset into this value to start looking at data values
* @param length number of data values to include in the hash computation
* @return ending hash value
*/
protected abstract int partialHash(int h, int offset, int length);
@Override
public String toString() {
return String.format("<ByteString@%s size=%d>",
Integer.toHexString(System.identityHashCode(this)), size());
}
}