2001-01-05 09:23:51 +01:00
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/* PipedWriter.java -- Write portion of piped character streams.
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Copyright (C) 1998, 2000, 2001 Free Software Foundation, Inc.
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1999-04-07 16:42:40 +02:00
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2000-04-21 03:18:16 +02:00
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This file is part of GNU Classpath.
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1999-04-07 16:42:40 +02:00
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2000-04-21 03:18:16 +02:00
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA.
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As a special exception, if you link this library with other files to
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produce an executable, this library does not by itself cause the
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resulting executable to be covered by the GNU General Public License.
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This exception does not however invalidate any other reasons why the
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executable file might be covered by the GNU General Public License. */
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1999-04-07 16:42:40 +02:00
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package java.io;
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2001-01-05 09:23:51 +01:00
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// NOTE: This implementation is very similar to that of PipedOutputStream.
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// If you fix a bug in here, chances are you should make a similar change to
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// the PipedOutputStream code.
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1999-04-07 16:42:40 +02:00
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/**
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2000-04-21 03:18:16 +02:00
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* This class writes its chars to a <code>PipedReader</code> to
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* which it is connected.
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* <p>
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* It is highly recommended that a <code>PipedWriter</code> and its
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* connected <code>PipedReader</code> be in different threads. If
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* they are in the same thread, read and write operations could deadlock
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* the thread.
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*
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* @author Aaron M. Renn (arenn@urbanophile.com)
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*/
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public class PipedWriter extends Writer
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{
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2001-01-05 09:23:51 +01:00
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/** Target PipedReader to which this is connected. Null only if this
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* Writer hasn't been connected yet. */
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PipedReader sink;
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/** Set to true if close() has been called on this Writer. */
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boolean closed;
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/** Buffer used to implement single-argument write */
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char[] read_buf = new char[1];
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/**
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* Create an unconnected PipedWriter. It must be connected
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* to a <code>PipedReader</code> using the <code>connect</code>
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* method prior to writing any data or an exception will be thrown.
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*/
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public PipedWriter()
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{
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}
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/**
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* Create a new <code>PipedWriter</code> instance
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* to write to the specified <code>PipedReader</code>. This stream
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* is then ready for writing.
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*
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* @param sink The <code>PipedReader</code> to connect this stream to.
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*
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* @exception IOException If <code>sink</code> has already been connected
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* to a different PipedWriter.
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*/
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public PipedWriter(PipedReader sink) throws IOException
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{
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sink.connect(this);
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}
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/**
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* Connects this object to the specified <code>PipedReader</code>
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* object. This stream will then be ready for writing.
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*
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* @param sink The <code>PipedReader</code> to connect this stream to
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*
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* @exception IOException If the stream has not been connected or has
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* been closed.
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*/
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public void connect(PipedReader sink) throws IOException
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{
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if (sink != null)
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throw new IOException ("Already connected");
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sink.connect(this);
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}
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/**
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* Write a single char of date to the stream. Note that this method will
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* block if the <code>PipedReader</code> to which this object is
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* connected has a full buffer.
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*
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* @param b The char of data to be written, passed as an <code>int</code>.
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*
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* @exception IOException If the stream has not been connected or has
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* been closed.
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*/
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public void write(char b) throws IOException
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{
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read_buf[0] = b;
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sink.receive (read_buf, 0, 1);
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}
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/**
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* This method writes <code>len</code> chars of data from the char array
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* <code>buf</code> starting at index <code>offset</code> in the array
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* to the stream. Note that this method will block if the
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* <code>PipedReader</code> to which this object is connected has
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* a buffer that cannot hold all of the chars to be written.
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*
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* @param buf The array containing chars to write to the stream.
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* @param offset The index into the array to start writing chars from.
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* @param len The number of chars to write.
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*
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* @exception IOException If the stream has not been connected or has
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* been closed.
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*/
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public void write(char[] b, int off, int len) throws IOException
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{
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if (sink == null)
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throw new IOException ("Not connected");
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if (closed)
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throw new IOException ("Pipe closed");
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sink.receive (b, off, len);
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}
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/**
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* This method does nothing.
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*
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* @exception IOException If the stream is closed.
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* @specnote You'd think that this method would block until the sink
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* had read all available data. Thats not the case - this method
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* appears to be a no-op?
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*/
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2001-02-20 20:01:55 +01:00
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public void flush() throws IOException
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2001-01-05 09:23:51 +01:00
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{
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2001-02-20 20:01:55 +01:00
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if (closed)
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throw new IOException ("Pipe closed");
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2001-01-05 09:23:51 +01:00
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}
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/**
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* This method closes this stream so that no more data can be written
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* to it. Any further attempts to write to this stream may throw an
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* exception
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*
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* @exception IOException If an error occurs
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*/
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public void close()
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{
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// A close call on an unconnected PipedWriter has no effect.
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if (sink != null)
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{
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closed = true;
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// Notify any waiting readers that the stream is now closed.
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synchronized (sink)
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{
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sink.notifyAll();
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}
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}
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}
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1999-04-07 16:42:40 +02:00
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}
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