/*
 * Copyright (c) 1996, 2006, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

package java.io;


/**
 * Piped character-output streams.
 *
 * @author Mark Reinhold
 * @since JDK1.1
 */

public class PipedWriter extends Writer {

 /* REMIND: identification of the read and write sides needs to be
 more sophisticated. Either using thread groups (but what about
 pipes within a thread?) or using finalization (but it may be a
 long time until the next GC). */
 private PipedReader sink;

 /* This flag records the open status of this particular writer. It
 * is independent of the status flags defined in PipedReader. It is
 * used to do a sanity check on connect.
 */
 private boolean closed = false;

 /**
 * Creates a piped writer connected to the specified piped
 * reader. Data characters written to this stream will then be
 * available as input from <code>snk</code>.
 *
 * @param snk The piped reader to connect to.
 * @exception IOException if an I/O error occurs.
 */
 public PipedWriter(PipedReader snk) throws IOException {
 connect(snk);
 }

 /**
 * Creates a piped writer that is not yet connected to a
 * piped reader. It must be connected to a piped reader,
 * either by the receiver or the sender, before being used.
 *
 * @see java.io.PipedReader#connect(java.io.PipedWriter)
 * @see java.io.PipedWriter#connect(java.io.PipedReader)
 */
 public PipedWriter() {
 }

 /**
 * Connects this piped writer to a receiver. If this object
 * is already connected to some other piped reader, an
 * <code>IOException</code> is thrown.
 * <p>
 * If <code>snk</code> is an unconnected piped reader and
 * <code>src</code> is an unconnected piped writer, they may
 * be connected by either the call:
 * <blockquote><pre>
 * src.connect(snk)</pre></blockquote>
 * or the call:
 * <blockquote><pre>
 * snk.connect(src)</pre></blockquote>
 * The two calls have the same effect.
 *
 * @param snk the piped reader to connect to.
 * @exception IOException if an I/O error occurs.
 */
 public synchronized void connect(PipedReader snk) throws IOException {
 if (snk == null) {
 throw new NullPointerException();
 } else if (sink != null || snk.connected) {
 throw new IOException("Already connected");
 } else if (snk.closedByReader || closed) {
 throw new IOException("Pipe closed");
 }

 sink = snk;
 snk.in = -1;
 snk.out = 0;
 snk.connected = true;
 }

 /**
 * Writes the specified <code>char</code> to the piped output stream.
 * If a thread was reading data characters from the connected piped input
 * stream, but the thread is no longer alive, then an
 * <code>IOException</code> is thrown.
 * <p>
 * Implements the <code>write</code> method of <code>Writer</code>.
 *
 * @param c the <code>char</code> to be written.
 * @exception IOException if the pipe is
 * <a href=PipedOutputStream.html#BROKEN> <code>broken</code></a>,
 * {@link #connect(java.io.PipedReader) unconnected}, closed
 * or an I/O error occurs.
 */
 public void write(int c) throws IOException {
 if (sink == null) {
 throw new IOException("Pipe not connected");
 }
 sink.receive(c);
 }

 /**
 * Writes <code>len</code> characters from the specified character array
 * starting at offset <code>off</code> to this piped output stream.
 * This method blocks until all the characters are written to the output
 * stream.
 * If a thread was reading data characters from the connected piped input
 * stream, but the thread is no longer alive, then an
 * <code>IOException</code> is thrown.
 *
 * @param cbuf the data.
 * @param off the start offset in the data.
 * @param len the number of characters to write.
 * @exception IOException if the pipe is
 * <a href=PipedOutputStream.html#BROKEN> <code>broken</code></a>,
 * {@link #connect(java.io.PipedReader) unconnected}, closed
 * or an I/O error occurs.
 */
 public void write(char cbuf[], int off, int len) throws IOException {
 if (sink == null) {
 throw new IOException("Pipe not connected");
 } else if ((off | len | (off + len) | (cbuf.length - (off + len))) < 0) {
 throw new IndexOutOfBoundsException();
 }
 sink.receive(cbuf, off, len);
 }

 /**
 * Flushes this output stream and forces any buffered output characters
 * to be written out.
 * This will notify any readers that characters are waiting in the pipe.
 *
 * @exception IOException if the pipe is closed, or an I/O error occurs.
 */
 public synchronized void flush() throws IOException {
 if (sink != null) {
 if (sink.closedByReader || closed) {
 throw new IOException("Pipe closed");
 }
 synchronized (sink) {
 sink.notifyAll();
 }
 }
 }

 /**
 * Closes this piped output stream and releases any system resources
 * associated with this stream. This stream may no longer be used for
 * writing characters.
 *
 * @exception IOException if an I/O error occurs.
 */
 public void close() throws IOException {
 closed = true;
 if (sink != null) {
 sink.receivedLast();
 }
 }
}