001// XMLFilter.java - filter SAX2 events.
002// Written by David Megginson, sax@megginson.com
003// NO WARRANTY!  This class is in the Public Domain.
004
005// $Id: XMLFilter.java,v 1.1 2001/03/05 21:40:06 jstrachan Exp $
006
007
008package org.xml.sax;
009
010
011/**
012 * Interface for an XML filter.
013 *
014 * <blockquote>
015 * <em>This module, both source code and documentation, is in the
016 * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
017 * </blockquote>
018 *
019 * <p>An XML filter is like an XML reader, except that it obtains its
020 * events from another XML reader rather than a primary source like
021 * an XML document or database.  Filters can modify a stream of
022 * events as they pass on to the final application.</p>
023 *
024 * <p>The XMLFilterImpl helper class provides a convenient base
025 * for creating SAX2 filters, by passing on all {@link org.xml.sax.EntityResolver
026 * EntityResolver}, {@link org.xml.sax.DTDHandler DTDHandler},
027 * {@link org.xml.sax.ContentHandler ContentHandler} and {@link org.xml.sax.ErrorHandler
028 * ErrorHandler} events automatically.</p>
029 *
030 * @since SAX 2.0
031 * @author David Megginson, 
032 *         <a href="mailto:sax@megginson.com">sax@megginson.com</a>
033 * @version 2.0
034 * @see org.xml.sax.helpers.XMLFilterImpl
035 */
036public interface XMLFilter extends XMLReader
037{
038
039    /**
040     * Set the parent reader.
041     *
042     * <p>This method allows the application to link the filter to
043     * a parent reader (which may be another filter).  The argument
044     * may not be null.</p>
045     *
046     * @param parent The parent reader.
047     */
048    public abstract void setParent (XMLReader parent);
049
050
051    /**
052     * Get the parent reader.
053     *
054     * <p>This method allows the application to query the parent
055     * reader (which may be another filter).  It is generally a
056     * bad idea to perform any operations on the parent reader
057     * directly: they should all pass through this filter.</p>
058     *
059     * @return The parent filter, or null if none has been set.
060     */
061    public abstract XMLReader getParent ();
062
063}
064
065// end of XMLFilter.java