content: /*
   * Copyright (c) 1996, 2006, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  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     PipedReader#connect(PipedWriter)
       * @see     PipedWriter#connect(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(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(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();
          }
      }
  }
  