org.apache.xmlbeans.impl.common.PushedInputStream Maven / Gradle / Ivy
/* Copyright 2004 The Apache Software Foundation
*
* 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 org.apache.xmlbeans.impl.common;
import java.io.IOException;
import java.io.OutputStream;
import java.io.InputStream;
public abstract class PushedInputStream extends InputStream
{
private static int defaultBufferSize = 2048;
protected byte buf[];
protected int writepos;
protected int readpos;
protected int markpos = -1;
protected int marklimit;
protected OutputStream outputStream = new InternalOutputStream();
/**
* Called when more bytes need to be written into this stream
* (as an OutputStream).
*
* This method must write at least one byte if the stream is
* not ended, and it must not write any bytes if the stream has
* already ended.
*/
protected abstract void fill(int requestedBytes) throws IOException;
/**
* Returns the linked output stream.
*
* This is the output stream that must be written to whenever
* the fill method is called.
*/
public final OutputStream getOutputStream()
{
return outputStream;
}
public PushedInputStream()
{
this(defaultBufferSize);
}
public PushedInputStream(int size)
{
if (size < 0)
{
throw new IllegalArgumentException("Negative initial buffer size");
}
buf = new byte[size];
}
/**
* Makes room for cb more bytes of data
*/
private void shift(int cb)
{
int savepos = readpos;
if (markpos > 0)
{
if (readpos - markpos > marklimit)
markpos = -1;
else
savepos = markpos;
}
int size = writepos - savepos;
if (savepos > 0 && buf.length - size >= cb && size <= cb)
{
System.arraycopy(buf, savepos, buf, 0, size);
}
else
{
int newcount = size + cb;
byte newbuf[] = new byte[Math.max(buf.length << 1, newcount)];
System.arraycopy(buf, savepos, newbuf, 0, size);
buf = newbuf;
}
if (savepos > 0)
{
readpos -= savepos;
if (markpos > 0)
markpos -= savepos;
writepos -= savepos;
}
}
public synchronized int read() throws IOException
{
if (readpos >= writepos)
{
fill(1);
if (readpos >= writepos)
return -1;
}
return buf[readpos++] & 0xff;
}
/**
* Read characters into a portion of an array, reading from the underlying
* stream at most once if necessary.
*/
public synchronized int read(byte[] b, int off, int len) throws IOException
{
int avail = writepos - readpos;
if (avail < len)
{
fill(len - avail);
avail = writepos - readpos;
if (avail <= 0) return -1;
}
int cnt = (avail < len) ? avail : len;
System.arraycopy(buf, readpos, b, off, cnt);
readpos += cnt;
return cnt;
}
public synchronized long skip(long n) throws IOException
{
if (n <= 0)
return 0;
long avail = writepos - readpos;
if (avail < n)
{
// Fill in buffer to save bytes for reset
long req = n - avail;
if (req > Integer.MAX_VALUE)
req = Integer.MAX_VALUE;
fill((int)req);
avail = writepos - readpos;
if (avail <= 0)
return 0;
}
long skipped = (avail < n) ? avail : n;
readpos += skipped;
return skipped;
}
public synchronized int available()
{
return writepos - readpos;
}
public synchronized void mark(int readlimit)
{
marklimit = readlimit;
markpos = readpos;
}
public synchronized void reset() throws IOException
{
if (markpos < 0)
throw new IOException("Resetting to invalid mark");
readpos = markpos;
}
public boolean markSupported()
{
return true;
}
private class InternalOutputStream extends OutputStream
{
public synchronized void write(int b) throws IOException
{
if (writepos + 1 > buf.length)
{
shift(1);
}
buf[writepos] = (byte)b;
writepos += 1;
}
public synchronized void write(byte b[], int off, int len)
{
if ((off < 0) || (off > b.length) || (len < 0) ||
((off + len) > b.length) || ((off + len) < 0))
throw new IndexOutOfBoundsException();
else if (len == 0)
return;
if (writepos + len > buf.length)
shift(len);
System.arraycopy(b, off, buf, writepos, len);
writepos += len;
}
}
}