parseradapter.java

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// ParserAdapter.java - adapt a SAX1 Parser to a SAX2 XMLReader.
// Written by David Megginson, [e-mail]
// NO WARRANTY!  This class is in the public domain.

// $Id: ParserAdapter.java,v 1.4 2000/05/15 16:10:53 mojo Exp $

package org.xml.sax.helpers;

import java.io.IOException;
import java.util.Enumeration;

import org.xml.sax.Parser;	// deprecated
import org.xml.sax.InputSource;
import org.xml.sax.Locator;
import org.xml.sax.AttributeList; // deprecated
import org.xml.sax.EntityResolver;
import org.xml.sax.DTDHandler;
import org.xml.sax.DocumentHandler; // deprecated
import org.xml.sax.ErrorHandler;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;

import org.xml.sax.XMLReader;
import org.xml.sax.Attributes;
import org.xml.sax.ContentHandler;
import org.xml.sax.SAXNotRecognizedException;
import org.xml.sax.SAXNotSupportedException;


/**
 * Adapt a SAX1 Parser as a SAX2 XMLReader.
 *
 * <blockquote>
 * <em>This module, both source code and documentation, is in the
 * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
 * </blockquote>
 *
 * <p>This class wraps a SAX1 {@link org.xml.sax.Parser Parser}
 * and makes it act as a SAX2 {@link org.xml.sax.XMLReader XMLReader},
 * with feature, property, and Namespace support.  Note
 * that it is not possible to report {@link org.xml.sax.ContentHandler#skippedEntity
 * skippedEntity} events, since SAX1 does not make that information available.</p>
 *
 * <p>This adapter does not test for duplicate Namespace-qualified
 * attribute names.</p>
 *
 * @since SAX 2.0
 * @author David Megginson, 
 *         <a href="mailto:[e-mail]">[e-mail]</a>
 * @version 2.0
 * @see org.xml.sax.helpers.XMLReaderAdapter
 * @see org.xml.sax.XMLReader
 * @see org.xml.sax.Parser
 */
public class ParserAdapter implements XMLReader, DocumentHandler
{


    ////////////////////////////////////////////////////////////////////
    // Constructors.
    ////////////////////////////////////////////////////////////////////


    /**
     * Construct a new parser adapter.
     *
     * <p>Use the "org.xml.sax.parser" property to locate the
     * embedded SAX1 driver.</p>
     *
     * @exception org.xml.sax.SAXException If the embedded driver
     *            cannot be instantiated or if the
     *            org.xml.sax.parser property is not specified.
     */
    public ParserAdapter ()
      throws SAXException
    {
	super();

	String driver = System.getProperty("org.xml.sax.parser");

	try {
	    setup(ParserFactory.makeParser());
	} catch (ClassNotFoundException e1) {
	    throw new
		SAXException("Cannot find SAX1 driver class " +
			     driver, e1);
	} catch (IllegalAccessException e2) {
	    throw new
		SAXException("SAX1 driver class " +
			     driver +
			     " found but cannot be loaded", e2);
	} catch (InstantiationException e3) {
	    throw new
		SAXException("SAX1 driver class " +
			     driver +
			     " loaded but cannot be instantiated", e3);
	} catch (ClassCastException e4) {
	    throw new
		SAXException("SAX1 driver class " +
			     driver +
			     " does not implement org.xml.sax.Parser");
	} catch (NullPointerException e5) {
	    throw new 
		SAXException("System property org.xml.sax.parser not specified");
	}
    }


    /**
     * Construct a new parser adapter.
     *
     * <p>Note that the embedded parser cannot be changed once the
     * adapter is created; to embed a different parser, allocate
     * a new ParserAdapter.</p>
     *
     * @param parser The SAX1 parser to embed.
     * @exception java.lang.NullPointerException If the parser parameter
     *            is null.
     */
    public ParserAdapter (Parser parser)
    {
	super();
	setup(parser);
    }


    /**
     * Internal setup method.
     *
     * @param parser The embedded parser.
     * @exception java.lang.NullPointerException If the parser parameter
     *            is null.
     */
    private void setup (Parser parser)
    {
	if (parser == null) {
	    throw new
		NullPointerException("Parser argument must not be null");
	}
	this.parser = parser;
	atts = new AttributesImpl();
	nsSupport = new NamespaceSupport();
	attAdapter = new AttributeListAdapter();
    }



    ////////////////////////////////////////////////////////////////////
    // Implementation of org.xml.sax.XMLReader.
    ////////////////////////////////////////////////////////////////////


    //
    // Internal constants for the sake of convenience.
    //
    private final static String FEATURES = "http://xml.org/sax/features/";
    private final static String NAMESPACES = FEATURES + "namespaces";
    private final static String NAMESPACE_PREFIXES = FEATURES + "namespace-prefixes";
    private final static String VALIDATION = FEATURES + "validation";
    private final static String EXTERNAL_GENERAL =
	FEATURES + "external-general-entities";
    private final static String EXTERNAL_PARAMETER =
	FEATURES + "external-parameter-entities";


    /**
     * Set a feature for the parser.
     *
     * <p>The only features supported are namespaces and 
     * namespace-prefixes.</p>
     *
     * @param name The feature name, as a complete URI.
     * @param state The requested feature state.
     * @exception org.xml.sax.SAXNotRecognizedException If the feature
     *            name is not known.
     * @exception org.xml.sax.SAXNotSupportedException If the feature
     *            state is not supported.
     * @see org.xml.sax.XMLReader#setFeature
     */
    public void setFeature (String name, boolean state)
	throws SAXNotRecognizedException, SAXNotSupportedException
    {
	if (name.equals(NAMESPACES)) {
	    checkNotParsing("feature", name);
	    namespaces = state;
	    if (!namespaces && !prefixes) {
		prefixes = true;
	    }
	} else if (name.equals(NAMESPACE_PREFIXES)) {
	    checkNotParsing("feature", name);
	    prefixes = state;
	    if (!prefixes && !namespaces) {
		namespaces = true;
	    }
	} else if (name.equals(VALIDATION) ||
		   name.equals(EXTERNAL_GENERAL) ||
		   name.equals(EXTERNAL_PARAMETER)) {
	    throw new SAXNotSupportedException("Feature: " + name);
	} else {
	    throw new SAXNotRecognizedException("Feature: " + name);
	}
    }


    /**
     * Check a parser feature.
     *
     * <p>The only features supported are namespaces and 
     * namespace-prefixes.</p>
     *
     * @param name The feature name, as a complete URI.
     * @return The current feature state.
     * @exception org.xml.sax.SAXNotRecognizedException If the feature
     *            name is not known.
     * @exception org.xml.sax.SAXNotSupportedException If querying the
     *            feature state is not supported.
     * @see org.xml.sax.XMLReader#setFeature
     */
    public boolean getFeature (String name)
	throws SAXNotRecognizedException, SAXNotSupportedException
    {
	if (name.equals(NAMESPACES)) {
	    return namespaces;
	} else if (name.equals(NAMESPACE_PREFIXES)) {
	    return prefixes;
	} else if (name.equals(VALIDATION) ||
		   name.equals(EXTERNAL_GENERAL) ||
		   name.equals(EXTERNAL_PARAMETER)) {
	    throw new SAXNotSupportedException("Feature: " + name);
	} else {
	    throw new SAXNotRecognizedException("Feature: " + name);
	}
    }


    /**
     * Set a parser property.
     *
     * <p>No special properties are currently supported.</p>
     *
     * @param name The property name.
     * @param value The property value.
     * @exception org.xml.sax.SAXNotRecognizedException If the feature
     *            name is not known.
     * @exception org.xml.sax.SAXNotSupportedException If the feature
     *            state is not supported.
     * @see org.xml.sax.XMLReader#setProperty
     */
    public void setProperty (String name, Object value)
	throws SAXNotRecognizedException, SAXNotSupportedException
    {
	throw new SAXNotRecognizedException("Property: " + name);
    }


    /**
     * Get a parser property.
     *
     * <p>No special properties are currently supported.</p>
     *
     * @param name The property name.
     * @return The property value.
     * @exception org.xml.sax.SAXNotRecognizedException If the feature
     *            name is not known.
     * @exception org.xml.sax.SAXNotSupportedException If the feature
     *            state is not supported.
     * @see org.xml.sax.XMLReader#getProperty
     */
    public Object getProperty (String name)
	throws SAXNotRecognizedException, SAXNotSupportedException
    {
	throw new SAXNotRecognizedException("Property: " + name);
    }


    /**
     * Set the entity resolver.
     *
     * @param resolver The new entity resolver.
     * @exception java.lang.NullPointerException If the entity resolver
     *            parameter is null.
     * @see org.xml.sax.XMLReader#setEntityResolver
     */
    public void setEntityResolver (EntityResolver resolver)
    {
	if (resolver == null) {
	    throw new NullPointerException("Null entity resolver");
	}
	entityResolver = resolver;
    }


    /**
     * Return the current entity resolver.
     *
     * @return The current entity resolver, or null if none was supplied.
     * @see org.xml.sax.XMLReader#getEntityResolver
     */
    public EntityResolver getEntityResolver ()
    {
	return entityResolver;
    }


    /**
     * Set the DTD handler.
     *
     * @param resolver The new DTD handler.
     * @exception java.lang.NullPointerException If the DTD handler
     *            parameter is null.
     * @see org.xml.sax.XMLReader#setEntityResolver
     */
    public void setDTDHandler (DTDHandler handler)
    {
	if (handler == null) {
	    throw new NullPointerException("Null DTD handler");
	}
	dtdHandler = handler;
    }


    /**
     * Return the current DTD handler.
     *
     * @return The current DTD handler, or null if none was supplied.
     * @see org.xml.sax.XMLReader#getEntityResolver
     */
    public DTDHandler getDTDHandler ()
    {
	return dtdHandler;
    }


    /**
     * Set the content handler.
     *
     * @param resolver The new content handler.
     * @exception java.lang.NullPointerException If the content handler
     *            parameter is null.
     * @see org.xml.sax.XMLReader#setEntityResolver
     */
    public void setContentHandler (ContentHandler handler)
    {
	if (handler == null) {
	    throw new NullPointerException("Null content handler");
	}
	contentHandler = handler;
    }


    /**
     * Return the current content handler.
     *
     * @return The current content handler, or null if none was supplied.
     * @see org.xml.sax.XMLReader#getEntityResolver
     */
    public ContentHandler getContentHandler ()
    {
	return contentHandler;
    }


    /**
     * Set the error handler.
     *
     * @param resolver The new error handler.
     * @exception java.lang.NullPointerException If the error handler
     *            parameter is null.
     * @see org.xml.sax.XMLReader#setEntityResolver
     */
    public void setErrorHandler (ErrorHandler handler)
    {
	if (handler == null) {
	    throw new NullPointerException("Null error handler");
	}
	errorHandler = handler;
    }


    /**
     * Return the current error handler.
     *
     * @return The current error handler, or null if none was supplied.
     * @see org.xml.sax.XMLReader#getEntityResolver
     */
    public ErrorHandler getErrorHandler ()
    {
	return errorHandler;
    }


    /**
     * Parse an XML document.
     *
     * @param systemId The absolute URL of the document.
     * @exception java.io.IOException If there is a problem reading
     *            the raw content of the document.
     * @exception org.xml.sax.SAXException If there is a problem
     *            processing the document.
     * @see #parse(org.xml.sax.InputSource)
     * @see org.xml.sax.Parser#parse(java.lang.String)
     */
    public void parse (String systemId)
	throws IOException, SAXException
    {
	parse(new InputSource(systemId));
    }


    /**
     * Parse an XML document.
     *
     * @param input An input source for the document.
     * @exception java.io.IOException If there is a problem reading
     *            the raw content of the document.
     * @exception org.xml.sax.SAXException If there is a problem
     *            processing the document.
     * @see #parse(java.lang.String)
     * @see org.xml.sax.Parser#parse(org.xml.sax.InputSource)
     */
    public void parse (InputSource input)
	throws IOException, SAXException
    {
	if (parsing) {
	    throw new SAXException("Parser is already in use");
	}
	setupParser();
	parsing = true;
	try {
	    parser.parse(input);
	} finally {
	    parsing = false;
	}
	parsing = false;
    }



    ////////////////////////////////////////////////////////////////////
    // Implementation of org.xml.sax.DocumentHandler.
    ////////////////////////////////////////////////////////////////////


    /**
     * Adapt a SAX1 document locator event.
     *
     * @param locator A document locator.
     * @see org.xml.sax.ContentHandler#setDocumentLocator
     */
    public void setDocumentLocator (Locator locator)
    {
	this.locator = locator;
	if (contentHandler != null) {
	    contentHandler.setDocumentLocator(locator);
	}
    }


    /**
     * Adapt a SAX1 start document event.
     *
     * @exception org.xml.sax.SAXException The client may raise a
     *            processing exception.
     * @see org.xml.sax.DocumentHandler#startDocument
     */
    public void startDocument ()
	throws SAXException
    {
	if (contentHandler != null) {
	    contentHandler.startDocument();
	}
    }


    /**
     * Adapt a SAX1 end document event.
     *
     * @exception org.xml.sax.SAXException The client may raise a
     *            processing exception.
     * @see org.xml.sax.DocumentHandler#endDocument
     */
    public void endDocument ()
	throws SAXException
    {
	if (contentHandler != null) {
	    contentHandler.endDocument();
	}
    }


    /**
     * Adapt a SAX1 startElement event.
     *
     * <p>If necessary, perform Namespace processing.</p>
     *
     * @param qName The qualified (prefixed) name.
     * @param qAtts The XML 1.0 attribute list (with qnames).
     */
    public void startElement (String qName, AttributeList qAtts)
	throws SAXException
    {
				// If we're not doing Namespace
				// processing, dispatch this quickly.
	if (!namespaces) {
	    if (contentHandler != null) {