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// PipedReader.java - Piped character stream.
/* Copyright (C) 1998, 1999 Cygnus Solutions
This file is part of libgcj.
This software is copyrighted work licensed under the terms of the
Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
details. */
package java.io;
/**
* @author Tom Tromey <tromey@cygnus.com>
* @date September 25, 1998
*/
/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
* "The Java Language Specification", ISBN 0-201-63451-1
* Status: Complete to 1.1.
*/
public class PipedReader extends Reader
{
public void close () throws IOException
{
closed = true;
}
public void connect (PipedWriter src) throws IOException
{
if (closed)
throw new IOException ("already closed");
if (writer != null)
{
if (writer == src)
return;
throw new IOException ("already connected");
}
try
{
writer = src;
writer.connect(this);
}
catch (IOException e)
{
writer = null;
throw e;
}
}
public PipedReader ()
{
super ();
writer = null;
closed = false;
in = -1;
out = 0;
pipeBuffer = new char[1024];
}
public PipedReader (PipedWriter src) throws IOException
{
super ();
closed = false;
in = -1;
out = 0;
pipeBuffer = new char[1024];
connect (src);
}
public int read (char buf[], int offset, int count) throws IOException
{
if (closed)
throw new IOException ("closed");
if (count < 0)
throw new ArrayIndexOutOfBoundsException ();
int toCopy = count;
synchronized (lock)
{
while (toCopy > 0)
{
// Wait for data in the pipe. If the writer is closed and
// no data has been copied into the output buffer, return
// the magic EOF number.
while (in == -1)
{
if (writer.isClosed())
{
if (toCopy < count)
return count - toCopy;
return -1;
}
// Note that JCL doesn't say this is the right thing
// to do. Still, it feels right, and we must deal
// with an interrupt somehow.
try
{
lock.wait();
}
catch (InterruptedException e)
{
InterruptedIOException io
= new InterruptedIOException (e.getMessage());
io.bytesTransferred = count - toCopy;
throw io;
}
}
// Now copy some data from pipe into user buffer.
int len;
if (in < out)
len = pipeBuffer.length - out;
else
len = in - out;
len = len > toCopy ? toCopy : len;
System.arraycopy(pipeBuffer, out, buf, offset, len);
out += len;
if (out == pipeBuffer.length)
out = 0;
toCopy -= len;
offset += len;
// If we've read all the data, then reset so that we know
// there is nothing left to be read.
if (in == out)
in = -1;
// Tell anybody waiting for space in the buffer.
lock.notifyAll();
}
}
return count;
}
void receive (char buf[], int offset, int count) throws IOException
{
if (count < 0)
throw new ArrayIndexOutOfBoundsException ();
int original = count;
synchronized (lock)
{
while (count > 0)
{
// Wait until there is some space in the buffer.
while (in == out)
{
try
{
lock.wait();
}
catch (InterruptedException e)
{
// Turn interrupts into IO interrupts.
InterruptedIOException io
= new InterruptedIOException (e.getMessage());
io.bytesTransferred = original - count;
throw io;
}
}
// Compute destination in the pipe.
int base, len;
if (in == -1)
{
base = 0;
len = pipeBuffer.length;
}
else if (in < out)
{
base = in;
len = out - in;
}
else
{
base = in;
len = pipeBuffer.length - in;
}
int copyLen = len > count ? count : len;
// Copy data and update local state.
System.arraycopy(buf, offset, pipeBuffer, base, copyLen);
in = base + copyLen;
if (in == pipeBuffer.length)
in = 0;
count -= copyLen;
offset += copyLen;
// Tell anybody waiting for data.
lock.notifyAll();
}
}
}
boolean isClosed ()
{
return closed;
}
// The associated writer.
private PipedWriter writer;
// True if this reader has been closed.
boolean closed;
// Index of next character to overwrite when receive() is called.
// If -1, then that means the buffer is empty.
private int in;
// Index of next character to return from read().
private int out;
// The pipe buffer itself.
private char[] pipeBuffer;
}
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