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    
006    package 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     */
049    public 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