001// SAX error handler.
002// http://www.saxproject.org
003// No warranty; no copyright -- use this as you will.
004// $Id: ErrorHandler.java,v 1.1 2004/12/23 22:38:42 mark Exp $
005
006package org.xml.sax;
007
008
009/**
010 * Basic interface for SAX error handlers.
011 *
012 * <blockquote>
013 * <em>This module, both source code and documentation, is in the
014 * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
015 * See <a href='http://www.saxproject.org'>http://www.saxproject.org</a>
016 * for further information.
017 * </blockquote>
018 *
019 * <p>If a SAX application needs to implement customized error
020 * handling, it must implement this interface and then register an
021 * instance with the XML reader using the
022 * {@link org.xml.sax.XMLReader#setErrorHandler setErrorHandler}
023 * method.  The parser will then report all errors and warnings
024 * through this interface.</p>
025 *
026 * <p><strong>WARNING:</strong> If an application does <em>not</em>
027 * register an ErrorHandler, XML parsing errors will go unreported,
028 * except that <em>SAXParseException</em>s will be thrown for fatal errors.
029 * In order to detect validity errors, an ErrorHandler that does something
030 * with {@link #error error()} calls must be registered.</p>
031 *
032 * <p>For XML processing errors, a SAX driver must use this interface 
033 * in preference to throwing an exception: it is up to the application 
034 * to decide whether to throw an exception for different types of 
035 * errors and warnings.  Note, however, that there is no requirement that 
036 * the parser continue to report additional errors after a call to 
037 * {@link #fatalError fatalError}.  In other words, a SAX driver class 
038 * may throw an exception after reporting any fatalError.
039 * Also parsers may throw appropriate exceptions for non-XML errors.
040 * For example, {@link XMLReader#parse XMLReader.parse()} would throw
041 * an IOException for errors accessing entities or the document.</p>
042 *
043 * @since SAX 1.0
044 * @author David Megginson
045 * @version 2.0.1+ (sax2r3pre1)
046 * @see org.xml.sax.XMLReader#setErrorHandler
047 * @see org.xml.sax.SAXParseException 
048 */
049public interface ErrorHandler {
050    
051    
052    /**
053     * Receive notification of a warning.
054     *
055     * <p>SAX parsers will use this method to report conditions that
056     * are not errors or fatal errors as defined by the XML
057     * recommendation.  The default behaviour is to take no
058     * action.</p>
059     *
060     * <p>The SAX parser must continue to provide normal parsing events
061     * after invoking this method: it should still be possible for the
062     * application to process the document through to the end.</p>
063     *
064     * <p>Filters may use this method to report other, non-XML warnings
065     * as well.</p>
066     *
067     * @param exception The warning information encapsulated in a
068     *                  SAX parse exception.
069     * @exception org.xml.sax.SAXException Any SAX exception, possibly
070     *            wrapping another exception.
071     * @see org.xml.sax.SAXParseException 
072     */
073    public abstract void warning (SAXParseException exception)
074        throws SAXException;
075    
076    
077    /**
078     * Receive notification of a recoverable error.
079     *
080     * <p>This corresponds to the definition of "error" in section 1.2
081     * of the W3C XML 1.0 Recommendation.  For example, a validating
082     * parser would use this callback to report the violation of a
083     * validity constraint.  The default behaviour is to take no
084     * action.</p>
085     *
086     * <p>The SAX parser must continue to provide normal parsing
087     * events after invoking this method: it should still be possible
088     * for the application to process the document through to the end.
089     * If the application cannot do so, then the parser should report
090     * a fatal error even if the XML recommendation does not require
091     * it to do so.</p>
092     *
093     * <p>Filters may use this method to report other, non-XML errors
094     * as well.</p>
095     *
096     * @param exception The error information encapsulated in a
097     *                  SAX parse exception.
098     * @exception org.xml.sax.SAXException Any SAX exception, possibly
099     *            wrapping another exception.
100     * @see org.xml.sax.SAXParseException 
101     */
102    public abstract void error (SAXParseException exception)
103        throws SAXException;
104    
105    
106    /**
107     * Receive notification of a non-recoverable error.
108     *
109     * <p><strong>There is an apparent contradiction between the
110     * documentation for this method and the documentation for {@link
111     * org.xml.sax.ContentHandler#endDocument}.  Until this ambiguity
112     * is resolved in a future major release, clients should make no
113     * assumptions about whether endDocument() will or will not be
114     * invoked when the parser has reported a fatalError() or thrown
115     * an exception.</strong></p>
116     *
117     * <p>This corresponds to the definition of "fatal error" in
118     * section 1.2 of the W3C XML 1.0 Recommendation.  For example, a
119     * parser would use this callback to report the violation of a
120     * well-formedness constraint.</p>
121     *
122     * <p>The application must assume that the document is unusable
123     * after the parser has invoked this method, and should continue
124     * (if at all) only for the sake of collecting additional error
125     * messages: in fact, SAX parsers are free to stop reporting any
126     * other events once this method has been invoked.</p>
127     *
128     * @param exception The error information encapsulated in a
129     *                  SAX parse exception.  
130     * @exception org.xml.sax.SAXException Any SAX exception, possibly
131     *            wrapping another exception.
132     * @see org.xml.sax.SAXParseException
133     */
134    public abstract void fatalError (SAXParseException exception)
135        throws SAXException;
136    
137}
138
139// end of ErrorHandler.java