// SAX error handler.
// http://www.saxproject.org
// No warranty; no copyright -- use this as you will.
// $Id: ErrorHandler.java,v 1.10 2004/12/11 15:41:09 dog Exp $

package org.xml.sax;


/**
 * Basic interface for SAX error handlers.
 *
 * <blockquote>
 * <em>This module, both source code and documentation, is in the
 * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
 * See <a href='http://www.saxproject.org'>http://www.saxproject.org</a>
 * for further information.
 * </blockquote>
 *
 * <p>If a SAX application needs to implement customized error
 * handling, it must implement this interface and then register an
 * instance with the XML reader using the
 * {@link org.xml.sax.XMLReader#setErrorHandler setErrorHandler}
 * method.  The parser will then report all errors and warnings
 * through this interface.</p>
 *
 * <p><strong>WARNING:</strong> If an application does <em>not</em>
 * register an ErrorHandler, XML parsing errors will go unreported,
 * except that <em>SAXParseException</em>s will be thrown for fatal errors.
 * In order to detect validity errors, an ErrorHandler that does something
 * with {@link #error error()} calls must be registered.</p>
 *
 * <p>For XML processing errors, a SAX driver must use this interface 
 * in preference to throwing an exception: it is up to the application 
 * to decide whether to throw an exception for different types of 
 * errors and warnings.  Note, however, that there is no requirement that 
 * the parser continue to report additional errors after a call to 
 * {@link #fatalError fatalError}.  In other words, a SAX driver class 
 * may throw an exception after reporting any fatalError.
 * Also parsers may throw appropriate exceptions for non-XML errors.
 * For example, {@link XMLReader#parse XMLReader.parse()} would throw
 * an IOException for errors accessing entities or the document.</p>
 *
 * @since SAX 1.0
 * @author David Megginson
 * @version 2.0.1+ (sax2r3pre1)
 * @see org.xml.sax.XMLReader#setErrorHandler
 * @see org.xml.sax.SAXParseException 
 */
public interface ErrorHandler {
    
    
    /**
     * Receive notification of a warning.
     *
     * <p>SAX parsers will use this method to report conditions that
     * are not errors or fatal errors as defined by the XML
     * recommendation.  The default behaviour is to take no
     * action.</p>
     *
     * <p>The SAX parser must continue to provide normal parsing events
     * after invoking this method: it should still be possible for the
     * application to process the document through to the end.</p>
     *
     * <p>Filters may use this method to report other, non-XML warnings
     * as well.</p>
     *
     * @param exception The warning information encapsulated in a
     *                  SAX parse exception.
     * @exception org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.SAXParseException 
     */
    public abstract void warning (SAXParseException exception)
	throws SAXException;
    
    
    /**
     * Receive notification of a recoverable error.
     *
     * <p>This corresponds to the definition of "error" in section 1.2
     * of the W3C XML 1.0 Recommendation.  For example, a validating
     * parser would use this callback to report the violation of a
     * validity constraint.  The default behaviour is to take no
     * action.</p>
     *
     * <p>The SAX parser must continue to provide normal parsing
     * events after invoking this method: it should still be possible
     * for the application to process the document through to the end.
     * If the application cannot do so, then the parser should report
     * a fatal error even if the XML recommendation does not require
     * it to do so.</p>
     *
     * <p>Filters may use this method to report other, non-XML errors
     * as well.</p>
     *
     * @param exception The error information encapsulated in a
     *                  SAX parse exception.
     * @exception org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.SAXParseException 
     */
    public abstract void error (SAXParseException exception)
	throws SAXException;
    
    
    /**
     * Receive notification of a non-recoverable error.
     *
     * <p><strong>There is an apparent contradiction between the
     * documentation for this method and the documentation for {@link
     * org.xml.sax.ContentHandler#endDocument}.  Until this ambiguity
     * is resolved in a future major release, clients should make no
     * assumptions about whether endDocument() will or will not be
     * invoked when the parser has reported a fatalError() or thrown
     * an exception.</strong></p>
     *
     * <p>This corresponds to the definition of "fatal error" in
     * section 1.2 of the W3C XML 1.0 Recommendation.  For example, a
     * parser would use this callback to report the violation of a
     * well-formedness constraint.</p>
     *
     * <p>The application must assume that the document is unusable
     * after the parser has invoked this method, and should continue
     * (if at all) only for the sake of collecting additional error
     * messages: in fact, SAX parsers are free to stop reporting any
     * other events once this method has been invoked.</p>
     *
     * @param exception The error information encapsulated in a
     *                  SAX parse exception.  
     * @exception org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.SAXParseException
     */
    public abstract void fatalError (SAXParseException exception)
	throws SAXException;
    
}

// end of ErrorHandler.java