fop/src/org/apache/fop/tools/DocumentReader.java

/* 
 * Copyright (C) 2001 The Apache Software Foundation. All rights reserved.
 * For details on use and redistribution please refer to the 
 * LICENSE file included with these sources."
 */


package org.apache.fop.tools;

import java.io.IOException;
//import java.util.*;

// DOM
import org.w3c.dom.*;

// SAX
import org.xml.sax.*;
import org.xml.sax.helpers.AttributesImpl;

/**
 * This presents a DOM as an XMLReader to make it easy to use a Document
 * with a SAX-based implementation.
 *
 * @author Kelly A Campbell
 *
 */

public class DocumentReader implements XMLReader 
{
    
    ////////////////////////////////////////////////////////////////////
    // Configuration.
    ////////////////////////////////////////////////////////////////////
    private boolean _namespaces = true;
    private boolean _namespace_prefixes = true;
    

    /**
     * Look up the value of a feature.
     *
     * <p>The feature name is any fully-qualified URI.  It is
     * possible for an XMLReader to recognize a feature name but
     * to be unable to return its value; this is especially true
     * in the case of an adapter for a SAX1 Parser, which has
     * no way of knowing whether the underlying parser is
     * performing validation or expanding external entities.</p>
     *
     * <p>All XMLReaders are required to recognize the
     * http://xml.org/sax/features/namespaces and the
     * http://xml.org/sax/features/namespace-prefixes feature names.</p>
     *
     * <p>Some feature values may be available only in specific
     * contexts, such as before, during, or after a parse.</p>
     *
     * <p>Typical usage is something like this:</p>
     *
     * <pre>
     * XMLReader r = new MySAXDriver();
     *
     *                         // try to activate validation
     * try {
     *   r.setFeature("http://xml.org/sax/features/validation", true);
     * } catch (SAXException e) {
     *   System.err.println("Cannot activate validation."); 
     * }
     *
     *                         // register event handlers
     * r.setContentHandler(new MyContentHandler());
     * r.setErrorHandler(new MyErrorHandler());
     *
     *                         // parse the first document
     * try {
     *   r.parse("http://www.foo.com/mydoc.xml");
     * } catch (IOException e) {
     *   System.err.println("I/O exception reading XML document");
     * } catch (SAXException e) {
     *   System.err.println("XML exception reading document.");
     * }
     * </pre>
     *
     * <p>Implementors are free (and encouraged) to invent their own features,
     * using names built on their own URIs.</p>
     *
     * @param name The feature name, which is a fully-qualified URI.
     * @return The current state of the feature (true or false).
     * @exception org.xml.sax.SAXNotRecognizedException When the
     *            XMLReader does not recognize the feature name.
     * @exception org.xml.sax.SAXNotSupportedException When the
     *            XMLReader recognizes the feature name but 
     *            cannot determine its value at this time.
     * @see #setFeature
     */
    public boolean getFeature (String name)
        throws SAXNotRecognizedException, SAXNotSupportedException 
    {
	if ("http://xml.org/sax/features/namespaces".equals(name)) {
	    return _namespaces;
	}
	else if ("http://xml.org/sax/features/namespace-prefixes".equals(name)) {
	    return _namespace_prefixes;
	}
	else {
	    throw new SAXNotRecognizedException("Feature '"+name+"' not recognized or supported by Document2SAXAdapter");
	}
	
    }
    


    /**
     * Set the state of a feature.
     *
     * <p>The feature name is any fully-qualified URI.  It is
     * possible for an XMLReader to recognize a feature name but
     * to be unable to set its value; this is especially true
     * in the case of an adapter for a SAX1 {@link org.xml.sax.Parser Parser},
     * which has no way of affecting whether the underlying parser is
     * validating, for example.</p>
     *
     * <p>All XMLReaders are required to support setting
     * http://xml.org/sax/features/namespaces to true and
     * http://xml.org/sax/features/namespace-prefixes to false.</p>
     *
     * <p>Some feature values may be immutable or mutable only 
     * in specific contexts, such as before, during, or after 
     * a parse.</p>
     *
     * @param name The feature name, which is a fully-qualified URI.
     * @param state The requested state of the feature (true or false).
     * @exception org.xml.sax.SAXNotRecognizedException When the
     *            XMLReader does not recognize the feature name.
     * @exception org.xml.sax.SAXNotSupportedException When the
     *            XMLReader recognizes the feature name but 
     *            cannot set the requested value.
     * @see #getFeature
     */
    public void setFeature (String name, boolean value)
	throws SAXNotRecognizedException, SAXNotSupportedException
    {
	if ("http://xml.org/sax/features/namespaces".equals(name)) {
	    _namespaces = value;
	}
	else if ("http://xml.org/sax/features/namespace-prefixes".equals(name)) {
	    _namespace_prefixes = value;
	}
	else {
	    throw new SAXNotRecognizedException("Feature '"+name+"' not recognized or supported by Document2SAXAdapter");
	}
	
    }
    


    /**
     * Look up the value of a property.
     *
     * <p>The property name is any fully-qualified URI.  It is
     * possible for an XMLReader to recognize a property name but
     * to be unable to return its state; this is especially true
     * in the case of an adapter for a SAX1 {@link org.xml.sax.Parser
     * Parser}.</p>
     *
     * <p>XMLReaders are not required to recognize any specific
     * property names, though an initial core set is documented for
     * SAX2.</p>
     *
     * <p>Some property values may be available only in specific
     * contexts, such as before, during, or after a parse.</p>
     *
     * <p>Implementors are free (and encouraged) to invent their own properties,
     * using names built on their own URIs.</p>
     *
     * @param name The property name, which is a fully-qualified URI.
     * @return The current value of the property.
     * @exception org.xml.sax.SAXNotRecognizedException When the
     *            XMLReader does not recognize the property name.
     * @exception org.xml.sax.SAXNotSupportedException When the
     *            XMLReader recognizes the property name but 
     *            cannot determine its value at this time.
     * @see #setProperty
     */
    public Object getProperty (String name)
	throws SAXNotRecognizedException, SAXNotSupportedException 
    {
	throw new SAXNotRecognizedException("Property '"+name+"' not recognized or supported by Document2SAXAdapter");
    }
    


    /**
     * Set the value of a property.
     *
     * <p>The property name is any fully-qualified URI.  It is
     * possible for an XMLReader to recognize a property name but
     * to be unable to set its value; this is especially true
     * in the case of an adapter for a SAX1 {@link org.xml.sax.Parser
     * Parser}.</p>
     *
     * <p>XMLReaders are not required to recognize setting
     * any specific property names, though a core set is provided with 
     * SAX2.</p>
     *
     * <p>Some property values may be immutable or mutable only 
     * in specific contexts, such as before, during, or after 
     * a parse.</p>
     *
     * <p>This method is also the standard mechanism for setting
     * extended handlers.</p>
     *
     * @param name The property name, which is a fully-qualified URI.
     * @param state The requested value for the property.
     * @exception org.xml.sax.SAXNotRecognizedException When the
     *            XMLReader does not recognize the property name.
     * @exception org.xml.sax.SAXNotSupportedException When the
     *            XMLReader recognizes the property name but 
     *            cannot set the requested value.
     */
    public void setProperty (String name, Object value)
	throws SAXNotRecognizedException, SAXNotSupportedException
    {
	throw new SAXNotRecognizedException("Property '"+name+"' not recognized or supported by Document2SAXAdapter");
    }



    ////////////////////////////////////////////////////////////////////
    // Event handlers.
    ////////////////////////////////////////////////////////////////////
    private EntityResolver _entityResolver = null;
    private DTDHandler     _dtdHandler     = null;
    private ContentHandler _contentHandler = null;
    private ErrorHandler   _errorHandler   = null;
    

    /**
     * Allow an application to register an entity resolver.
     *
     * <p>If the application does not register an entity resolver,
     * the XMLReader will perform its own default resolution.</p>
     *
     * <p>Applications may register a new or different resolver in the
     * middle of a parse, and the SAX parser must begin using the new
     * resolver immediately.</p>
     *
     * @param resolver The entity resolver.
     * @exception java.lang.NullPointerException If the resolver 
     *            argument is null.
     * @see #getEntityResolver
     */
    public void setEntityResolver (EntityResolver resolver)
    {
	_entityResolver = resolver;
    }
    


    /**
     * Return the current entity resolver.
     *
     * @return The current entity resolver, or null if none
     *         has been registered.
     * @see #setEntityResolver
     */
    public EntityResolver getEntityResolver () 
    {
	return _entityResolver;
    }
    


    /**
     * Allow an application to register a DTD event handler.
     *
     * <p>If the application does not register a DTD handler, all DTD
     * events reported by the SAX parser will be silently ignored.</p>
     *
     * <p>Applications may register a new or different handler in the
     * middle of a parse, and the SAX parser must begin using the new
     * handler immediately.</p>
     *
     * @param handler The DTD handler.
     * @exception java.lang.NullPointerException If the handler 
     *            argument is null.
     * @see #getDTDHandler
     */
    public void setDTDHandler (DTDHandler handler)
    {
	_dtdHandler = handler;
    }
    


    /**
     * Return the current DTD handler.
     *
     * @return The current DTD handler, or null if none
     *         has been registered.
     * @see #setDTDHandler
     */
    public DTDHandler getDTDHandler () 
    {
	return _dtdHandler;
    }
    


    /**
     * Allow an application to register a content event handler.
     *
     * <p>If the application does not register a content handler, all
     * content events reported by the SAX parser will be silently
     * ignored.</p>
     *
     * <p>Applications may register a new or different handler in the
     * middle of a parse, and the SAX parser must begin using the new
     * handler immediately.</p>
     *
     * @param handler The content handler.
     * @exception java.lang.NullPointerException If the handler 
     *            argument is null.
     * @see #getContentHandler
     */
    public void setContentHandler (ContentHandler handler) 
    {
	_contentHandler = handler;
    }
    


    /**
     * Return the current content handler.
     *
     * @return The current content handler, or null if none
     *         has been registered.
     * @see #setContentHandler
     */
    public ContentHandler getContentHandler ()
    {
	return _contentHandler;
    }
    


    /**
     * Allow an application to register an error event handler.
     *
     * <p>If the application does not register an error handler, all
     * error events reported by the SAX parser will be silently
     * ignored; however, normal processing may not continue.  It is
     * highly recommended that all SAX applications implement an
     * error handler to avoid unexpected bugs.</p>
     *
     * <p>Applications may register a new or different handler in the
     * middle of a parse, and the SAX parser must begin using the new
     * handler immediately.</p>
     *
     * @param handler The error handler.
     * @exception java.lang.NullPointerException If the handler 
     *            argument is null.
     * @see #getErrorHandler
     */
    public void setErrorHandler (ErrorHandler handler) 
    {
	_errorHandler = handler;
    }
    
    /**
     * Return the current error handler.
     *
     * @return The current error handler, or null if none
     *         has been registered.
     * @see #setErrorHandler
     */
    public ErrorHandler getErrorHandler () 
    {
	return _errorHandler;
    }
    


    ////////////////////////////////////////////////////////////////////
    // Parsing.
    ////////////////////////////////////////////////////////////////////

    /**
     * Parse an XML DOM document.
     *
     * 
     *
     * @param source The input source for the top-level of the
     *        XML document.
     * @exception org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @exception java.io.IOException An IO exception from the parser,
     *            possibly from a byte stream or character stream
     *            supplied by the application.
     * @see org.xml.sax.InputSource
     * @see #parse(java.lang.String)
     * @see #setEntityResolver
     * @see #setDTDHandler
     * @see #setContentHandler
     * @see #setErrorHandler 
     */
    public void parse (InputSource input)
	throws IOException, SAXException
    {
	if (input instanceof DocumentInputSource) {
	    Document document = ((DocumentInputSource)input).getDocument();
	    if (_contentHandler == null) {
		throw new SAXException("ContentHandler is null. Please use setContentHandler()");
	    }
	    
	    // refactored from org.apache.fop.apps.Driver      
	    /* most of this code is modified from John Cowan's */

	    Node currentNode;
	    AttributesImpl currentAtts;
	    
	    /* temporary array for making Strings into character arrays */
	    char[] array = null;
	    
	    currentAtts = new AttributesImpl();
	    
	    /* start at the document element */
	    currentNode = document;
	    while (currentNode != null) {
		switch (currentNode.getNodeType()) {
		case Node.DOCUMENT_NODE:
		    _contentHandler.startDocument();
		    break;
		case Node.CDATA_SECTION_NODE:
		case Node.TEXT_NODE:
		    String data = currentNode.getNodeValue();
		    int datalen = data.length();
		    if (array == null || array.length < datalen) {
			/* if the array isn't big enough, make a new
			   one */
			array = new char[datalen];
		    }
		    data.getChars(0, datalen, array, 0);
		    _contentHandler.characters(array, 0, datalen);
		    break;
		case Node.PROCESSING_INSTRUCTION_NODE:
		    _contentHandler.processingInstruction(currentNode.getNodeName(),
							  currentNode.getNodeValue());
		    break;
		case Node.ELEMENT_NODE:
		    NamedNodeMap map = currentNode.getAttributes();
		    currentAtts.clear();
		    for (int i = map.getLength() - 1; i >= 0; i--) {
			Attr att = (Attr) map.item(i);
			currentAtts.addAttribute( att.getNamespaceURI(),
						  att.getLocalName(), att.getName(),
						  "CDATA", att.getValue());
		    }
		    _contentHandler.startElement(currentNode.getNamespaceURI(),
						 currentNode.getLocalName(),
						 currentNode.getNodeName(), 
						 currentAtts);
		    break;
                }
		
                Node nextNode = currentNode.getFirstChild();
                if (nextNode != null) {
                    currentNode = nextNode;
                    continue;
                }
		
                while (currentNode != null) {
                    switch (currentNode.getNodeType()) {
		    case Node.DOCUMENT_NODE:
			_contentHandler.endDocument();
			break;
		    case Node.ELEMENT_NODE:
			_contentHandler.endElement(currentNode.getNamespaceURI(),
						   currentNode.getLocalName(),
						   currentNode.getNodeName());
			break;
                    }
		    
                    nextNode = currentNode.getNextSibling();
                    if (nextNode != null) {
                        currentNode = nextNode;
                        break;
                    }
		    
                    currentNode = currentNode.getParentNode();
                }
            }
	    
	}
	else {
	    throw new SAXException("DocumentReader only supports parsing of a DocumentInputSource");
	}
	
    }
    


    /**
     * DocumentReader requires a DocumentInputSource, so this is not
     * implements and simply throws a SAXException. Use parse(DocumentInputSource) 
     * instead
     * 
     * @param systemId The system identifier (URI).
     * @exception org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @exception java.io.IOException An IO exception from the parser,
     *            possibly from a byte stream or character stream
     *            supplied by the application.
     * @see #parse(org.xml.sax.InputSource)
     */
    public void parse (String systemId)
	throws IOException, SAXException
    {
	throw new SAXException("DocumentReader only supports parsing of a DocumentInputSource");
    }
}