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/*
* Copyright 2016 Dmitry Avtonomov.
*
* 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 umich.ms.util;
import java.io.IOException;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.util.Arrays;
/**
* Auto-growing array of bytes, with access to the underlying data.
* Almost exactly follows Java's ByteArrayOutputStream, but gives access
* to underlying data and allows basic navigation.
* @author Dmitry Avtonomov
*/
public class ByteArrayHolder extends OutputStream {
/**
* The buffer where data is stored.
*/
protected byte buf[];
/**
* The number of valid bytes in the buffer.
*/
protected int count;
/**
* Creates a new byte array output stream, with a buffer capacity of
* the specified size, in bytes.
*
* @param size the initial size.
* @exception IllegalArgumentException if size is negative.
*/
public ByteArrayHolder(int size) {
if (size < 0) {
throw new IllegalArgumentException("Negative initial size: " + size);
}
buf = new byte[size];
count = 0;
}
/**
* Creates a new byte array output stream. The buffer capacity is
* initially 32 bytes, though its size increases if necessary.
*/
public ByteArrayHolder() {
this(32);
}
public ByteArrayHolder(byte[] underlyingBuf) {
this.buf = underlyingBuf;
this.count = underlyingBuf.length - 1;
}
/**
* Increases the capacity to ensure that it can hold at least the
* number of elements specified by the minimum capacity argument.
*
* @param minCapacity the desired minimum capacity
*/
private void grow(int minCapacity) {
// overflow-conscious code
int oldCapacity = buf.length;
int newCapacity = oldCapacity << 1;
if (newCapacity - minCapacity < 0)
newCapacity = minCapacity;
if (newCapacity < 0) {
if (minCapacity < 0) // overflow
throw new OutOfMemoryError();
newCapacity = Integer.MAX_VALUE;
}
//System.out.printf("Growing BAH-ol-method[%s] from %d to %d, new cap is: %d (%.2fkb)\n",
// System.identityHashCode(this), getCapacity(), minCapacity, newCapacity, newCapacity/1000d);
buf = Arrays.copyOf(buf, newCapacity);
}
private void grow(int minCapacity, boolean keepData) {
// overflow-conscious code
int oldCapacity = buf.length;
int newCapacity = oldCapacity << 1;
if (newCapacity - minCapacity < 0)
newCapacity = minCapacity;
if (newCapacity < 0) {
if (minCapacity < 0) // overflow
throw new OutOfMemoryError("Not enought memory to extend a ByteArrayHolder");
newCapacity = Integer.MAX_VALUE;
}
//System.out.printf("Growing BAH-my-method[%s] from %d to %d, new cap is: %d (%.2fkb)\n",
// System.identityHashCode(this), getCapacity(), minCapacity, newCapacity, newCapacity/1000d);
if (keepData) {
buf = Arrays.copyOf(buf, newCapacity);
} else {
buf = new byte[newCapacity];
}
}
/**
* Writes the specified byte to this byte array output stream.
*
* @param b the byte to be written.
*/
@Override
public synchronized void write(int b) {
ensureCapacity(count + 1);
buf[count] = (byte) b;
count += 1;
}
/**
* Writes len bytes from the specified byte array
* starting at offset off to this byte array output stream.
*
* @param b the data.
* @param off the start offset in the data.
* @param len the number of bytes to write.
*/
@Override
public synchronized void write(byte b[], int off, int len) {
if ((off < 0) || (off > b.length) || (len < 0) ||
((off + len) - b.length > 0)) {
throw new IndexOutOfBoundsException();
}
ensureCapacity(count + len);
System.arraycopy(b, off, buf, count, len);
count += len;
}
/**
* Writes the complete contents of this byte array output stream to
* the specified output stream argument, as if by calling the output
* stream's write method using out.write(buf, 0, count).
*
* @param out the output stream to which to write the data.
* @exception IOException if an I/O error occurs.
*/
public synchronized void writeTo(OutputStream out) throws IOException {
out.write(buf, 0, count);
}
/**
* Resets the count field of this byte array output
* stream to zero, 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.
*
* @see java.io.ByteArrayInputStream#count
*/
public synchronized void reset() {
count = 0;
}
/**
* Creates a newly allocated byte array. Its size is the current
* size of this output stream and the valid contents of the buffer
* have been copied into it.
*
* @return the current contents of this output stream, as a byte array.
* @see java.io.ByteArrayOutputStream#size()
*/
public synchronized byte toByteArray()[] {
return Arrays.copyOf(buf, count);
}
/**
* Returns the current size of the buffer.
*
* @return the value of the count field, which is the number
* of valid bytes in this output stream.
* @see java.io.ByteArrayOutputStream#count
*/
public synchronized int size() {
return count;
}
/**
* Converts the buffer's contents into a string decoding bytes using the
* platform's default character set. The length of the new String
* is a function of the character set, and hence may not be equal to the
* size of the buffer.
*
* This method always replaces malformed-input and unmappable-character
* sequences with the default replacement string for the platform's
* default character set. The {@linkplain java.nio.charset.CharsetDecoder}
* class should be used when more control over the decoding process is
* required.
*
* @return String decoded from the buffer's contents.
* @since JDK1.1
*/
@Override
public synchronized String toString() {
return new String(buf, 0, count);
}
/**
* Converts the buffer's contents into a string by decoding the bytes using
* the specified {@link java.nio.charset.Charset charsetName}. The length of
* the new String is a function of the charset, and hence may not be
* equal to the length of the byte array.
*
*
This method always replaces malformed-input and unmappable-character
* sequences with this charset's default replacement string. The {@link
* java.nio.charset.CharsetDecoder} class should be used when more control
* over the decoding process is required.
*
* @param charsetName the name of a supported
* {@link java.nio.charset.Charset } charset
* @return String decoded from the buffer's contents.
* @exception UnsupportedEncodingException
* If the named charset is not supported
* @since JDK1.1
*/
public synchronized String toString(String charsetName)
throws UnsupportedEncodingException
{
return new String(buf, 0, count, charsetName);
}
/**
* Creates a newly allocated string. Its size is the current size of
* the output stream and the valid contents of the buffer have been
* copied into it. Each character c in the resulting string is
* constructed from the corresponding element b in the byte
* array such that:
*
* c == (char)(((hibyte & 0xff) << 8) | (b & 0xff))
*
*
* @deprecated This method does not properly convert bytes into characters.
* As of JDK 1.1, the preferred way to do this is via the
* toString(String enc) method, which takes an encoding-name
* argument, or the toString() method, which uses the
* platform's default character encoding.
*
* @param hibyte the high byte of each resulting Unicode character.
* @return the current contents of the output stream, as a string.
* @see java.io.ByteArrayOutputStream#size()
* @see java.io.ByteArrayOutputStream#toString(String)
* @see java.io.ByteArrayOutputStream#toString()
*/
@Deprecated
public synchronized String toString(int hibyte) {
return new String(buf, hibyte, 0, count);
}
/**
* Closing a ByteArrayOutputStream has no effect. The methods in
* this class can be called after the stream has been closed without
* generating an IOException.
*
*
* @throws java.io.IOException
*/
@Override
public void close() throws IOException {
}
public ByteBuffer toByteBuffer() {
return ByteBuffer.wrap(this.buf, 0, size());
}
public byte[] getUnderlyingBytes() {
return buf;
}
public final int getCapacity() {
return buf.length;
}
public final int getCapacityLeft() {
return buf.length - count;
}
/**
* Increases the capacity if necessary to ensure that it can hold
* at least the number of elements specified by the minimum
* capacity argument.
*
* @param minCapacity the desired minimum capacity
* @throws OutOfMemoryError if {@code minCapacity < 0}. This is
* interpreted as a request for the unsatisfiably large capacity
* {@code (long) Integer.MAX_VALUE + (minCapacity - Integer.MAX_VALUE)}.
*/
public void ensureCapacity(int minCapacity) {
// overflow-conscious code
if (minCapacity - buf.length > 0)
grow(minCapacity);
}
/**
*
* @param minCapacity the min capacity to grow the underlying buffer to. The actual
* increased capacity might be more than that.
* @param keepData if true, will copy the previous contents of the buffer to the new one.
* If you are just reusing an old buffer for new data, you might want to set this to false, then
* the buffer will be reset.
*/
public void ensureCapacity(int minCapacity, boolean keepData) {
// overflow-conscious code
if (minCapacity - buf.length > 0) {
grow(minCapacity, keepData);
}
if (!keepData)
this.reset();
}
/**
* Checks if there is enough space in the buffer to write N additional bytes.
* Will grow the buffer if necessary.
* It takes current position in the buffer into account.
* @param numBytesToAdd the number of bytes you want to add to the buffer
*/
public void ensureHasSpace(int numBytesToAdd) {
if (numBytesToAdd < 0) {
throw new IllegalArgumentException("Number of bytes can't be negative");
}
int capacityLeft = getCapacityLeft();
if (capacityLeft < numBytesToAdd) {
grow(numBytesToAdd - capacityLeft, true);
}
}
/**
* This is the position of the next write to the underlying buffer.
* @return the number of valid bytes in the underlying buffer
*/
public final int getPosition() {
return this.size();
}
/**
* This is a dangerous method, be sure you know what you're doing.
* @param newPos
*/
public final void setPosition(int newPos) {
if (newPos > getCapacity()) {
throw new IndexOutOfBoundsException("New position can't be greater than the capacity");
}
if (newPos < 0) {
throw new IndexOutOfBoundsException("New position can't be less than zero");
}
count = newPos;
}
public final void clear() {
Arrays.fill(buf, (byte)0);
setPosition(0);
}
}