001/* FilterWriter.java -- Parent class for output streams that filter
002   Copyright (C) 1998, 1999, 2001, 2003, 2005  Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package java.io;
040
041/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
042 * "The Java Language Specification", ISBN 0-201-63451-1
043 * Status:  Complete to version 1.1.
044 */
045
046/**
047  * This class is the common superclass of output character stream classes
048  * that filter the output they write.  These classes typically transform the
049  * data in some way prior to writing it out to another underlying
050  * <code>Writer</code>.  This class simply overrides all the
051  * methods in <code>Writer</code> to redirect them to the
052  * underlying stream.  Subclasses provide actual filtering.
053  *
054  * @author Aaron M. Renn (arenn@urbanophile.com)
055  * @author Tom Tromey (tromey@cygnus.com)
056  */
057public abstract class FilterWriter extends Writer
058{
059  /**
060    * This is the subordinate <code>Writer</code> that this class
061    * redirects its method calls to.
062    */
063  protected Writer out;
064
065  /**
066    * This method initializes an instance of <code>FilterWriter</code>
067    * to write to the specified subordinate <code>Writer</code>.
068    * The given <code>Writer</code> will be used as <code>lock</code> for
069    * the newly created <code>FilterWriter</code>.
070    *
071    * @param out The <code>Writer</code> to write to
072    */
073  protected FilterWriter(Writer out)
074  {
075    super(out.lock);
076    this.out = out;
077  }
078
079  /**
080    * This method closes the underlying <code>Writer</code>.  Any
081    * further attempts to write to this stream may throw an exception.
082    *
083    * @exception IOException If an error occurs
084    */
085  public void close() throws IOException
086  {
087    out.close();
088  }
089
090  /**
091    * This method attempt to flush all buffered output to be written to the
092    * underlying output sink.
093    *
094    * @exception IOException If an error occurs
095    */
096  public void flush() throws IOException
097  {
098    out.flush();
099  }
100
101  /**
102    * This method writes a single char of output to the underlying
103    * <code>Writer</code>.
104    *
105    * @param b The char to write, passed as an int.
106    *
107    * @exception IOException If an error occurs
108    */
109  public void write(int b) throws IOException
110  {
111    out.write(b);
112  }
113
114  /**
115    * This method writes <code>len</code> chars from the array <code>buf</code>
116    * starting at index <code>offset</code> to the underlying
117    * <code>Writer</code>.
118    *
119    * @param buf The char array to write chars from
120    * @param offset The index into the array to start writing chars from
121    * @param len The number of chars to write
122    *
123    * @exception IOException If an error occurs
124    */
125  public void write(char[] buf, int offset, int len) throws IOException
126  {
127    out.write(buf, offset, len);
128  }
129
130  /**
131    * This method writes <code>len</code> chars from the <code>String</code>
132    * starting at position <code>offset</code>.
133    *
134    * @param str The <code>String</code> that is to be written
135    * @param offset The character offset into the <code>String</code>
136    * to start writing from
137    * @param len The number of chars to write
138    *
139    * @exception IOException If an error occurs
140    */
141  public void write(String str, int offset, int len) throws IOException
142  {
143    out.write(str, offset, len);
144  }
145
146} // class FilterWriter