183 lines
6.3 KiB
Java
183 lines
6.3 KiB
Java
/* PipedWriter.java -- Write portion of piped character streams.
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Copyright (C) 1998, 2000, 2001, 2003 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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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., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.io;
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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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/**
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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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/** 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 (this.sink != null || sink.source != 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(int b) throws IOException
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{
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read_buf[0] = (char) (b & 0xffff);
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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 buffer 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[] buffer, int offset, 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(buffer, offset, 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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public void flush() throws IOException
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{
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if (closed)
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throw new IOException ("Pipe closed");
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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() throws IOException
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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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}
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