Re: [basex-talk] Problem with DOM LS serialization

5 Feb 2013

      Dear Christian,

thank you for quickly attacking the problem! But sorry, but the problem is 
not fixed.I get the same error. 

I have a general note.

I have implemented a special serializer which implements org.xml.sax
.XMLReader. This is used to directly dispatch the query result to JAXB and 
to created objects.
I can now extend this technique to generate a new DOM by implementing a 
SAX ContentHandler which generates a DOM.

Unfortunately the serializer API is not documented nor stable (it changed 
from 7.3 to 7.5).
I propose to add a standard SAX serializer to BaseX. This would be a very 
useful extension.

Here is my implementation:

import static org.basex.util.Token.XMLNS;
import static org.basex.util.Token.startsWith;
import static org.basex.util.Token.string;
import static org.basex.util.Token.substring;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import org.basex.io.serial.Serializer;
import org.basex.query.value.item.Item;
import org.xml.sax.ContentHandler;
import org.xml.sax.DTDHandler;
import org.xml.sax.EntityResolver;
import org.xml.sax.ErrorHandler;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.SAXNotRecognizedException;
import org.xml.sax.SAXNotSupportedException;
import org.xml.sax.XMLReader;
import org.xml.sax.ext.LexicalHandler;
import org.xml.sax.helpers.AttributesImpl;

/**
 * Bridge to translate BaseX items to SAX events.
 * The parse() methods does the following:
 * <ol>
 * <li>notify startDocument()</li>
 * <li>serialize the item</li>
 * <li>notify endDocument()</li>
 */
public class FragmentSerializer extends Serializer implements XMLReader
{
        /**
         * The item to be serialized
         */
        private Item item;

        private ContentHandler contentHandler;
        private EntityResolver entityResolver;
        private DTDHandler dtdHandler;
        private ErrorHandler errorHandler;
        private LexicalHandler lexicalHandler;

        public FragmentSerializer()
        {
        }

        public Item getItem()
        {
                return item;
        }

        /**
         * Sets the item to be serialized.
         */
        public void setItem(Item item)
        {
                this.item = item;
        }

        //////////////////////////////////////////////////
        // XMLReader
        //////////////////////////////////////////////////

        @Override
        public ContentHandler getContentHandler()
        {
                return contentHandler;
        }

        @Override
        public boolean getFeature(final String name)
        {
                return false;
        }

        @Override
        public Object getProperty(final String name)
        {
                return null;
        }

        public void parse() throws SAXException
        {
                parse("");
        }

        @Override
        public void parse(final InputSource input) throws SAXException
        {
                parse("");
        }

        @Override
        public void parse(final String id) throws SAXException
        {
                try
                {
                        contentHandler.startDocument();
                        item.serialize(this);
                        contentHandler.endDocument();
                }
                catch (final Exception ex)
                {
                        throw new SAXException(ex);
                }
        }

        @Override
        public void setContentHandler(final ContentHandler c)
        {
                contentHandler = c;
        }

        public void setLexicalHandler(final LexicalHandler l)
        {
                lexicalHandler = l;
        }

        @Override
        public void setEntityResolver(EntityResolver entityResolver)
        {
                this.entityResolver = entityResolver;
        }

        @Override
        public EntityResolver getEntityResolver()
        {
                return entityResolver;
        }

        @Override
        public void setDTDHandler(DTDHandler dtdHandler)
        {
                this.dtdHandler = dtdHandler;
        }

        @Override
        public DTDHandler getDTDHandler()
        {
                return dtdHandler;
        }

        @Override
        public void setErrorHandler(ErrorHandler errorHandler)
        {
                this.errorHandler = errorHandler;
        }

        @Override
        public ErrorHandler getErrorHandler()
        {
                return errorHandler;
        }

        @Override
        public void setFeature(final String name, final boolean value) 
throws SAXNotRecognizedException, SAXNotSupportedException
        {
                throw new SAXNotRecognizedException();
        }

        @Override
        public void setProperty(final String name, final Object value) 
throws SAXNotRecognizedException, SAXNotSupportedException
        {
                throw new SAXNotRecognizedException();
        }

        //////////////////////////////////////////////////
        // Serializer
        //////////////////////////////////////////////////

        private final HashMap<String, String> attributes = new 
HashMap<String, String>();
        private NSDecl namespaces;

        @Override
        protected void startOpen(byte[] n) throws IOException
        {
                attributes.clear();
                this.namespaces = new NSDecl(this.namespaces);
        }

        @Override
        protected void attribute(byte[] n, byte[] v) throws IOException
        {
                String value = string(v);

                String prefix = null;
                if (startsWith(n, XMLNS))
                {
                        if (n.length == 5)
                        {
                                prefix = "";
                        }
                        else if (n[5] == ':')
                        {
                                prefix = string(substring(n, 6));
                        }
                }

                if (prefix != null)
                {
                        namespaces.put(prefix, value);
                }
                else
                {
                        String name = string(n);
                        attributes.put(name, value);
                }
        }

        @Override
        protected void finishOpen() throws IOException
        {
                try
                {
                        AttributesImpl attrs = new AttributesImpl();
                        for (Map.Entry<String, String> e : 
attributes.entrySet())
                        {
                                String rname = e.getKey();
                                String[] qname = qname(rname);
                                String ns = namespaces.get(qname[0]);
                                String lname = qname[1];
                                attrs.addAttribute(ns, lname, rname, null, 
e.getValue());
                        }

                        String rname = string(elem);
                        String[] qname = qname(rname);
                        String ns = namespaces.get(qname[0]);
                        String lname = qname[1];
                        contentHandler.startElement(ns, lname, rname, 
attrs);

//                      System.out.println("{" + ns + "}" + lname);
//                      for (int i = 0; i < attrs.getLength(); i++)
//                      {
//                              System.out.println("    {" + 
attrs.getURI(i) + "}" + attrs.getLocalName(i) + "=" + attrs.getValue(i));
//                      }
                }
                catch (final SAXException e)
                {
                        throw new IOException(e.getMessage());
                }
        }

        public String[] qname(String rname)
        {
                String prefix = "";
                String lname = rname;

                int i = rname.indexOf(':');
                if (i > 0)
                {
                        prefix = rname.substring(0, i);
                        lname = rname.substring(i + 1);
                }
                return new String[] { prefix, lname };
        }

        @Override
        protected void finishEmpty() throws IOException
        {
                finishOpen();
                finishClose();
        }

        @Override
        protected void finishClose() throws IOException
        {
                try
                {
                        String name = string(elem);
                        contentHandler.endElement("", name, name);
                        this.namespaces = namespaces.getParent();
                }
                catch (final SAXException e)
                {
                        throw new IOException(e.getMessage());
                }
        }

        @Override
        protected void finishText(byte[] text) throws IOException
        {
                try
                {
                        String s = string(text);
                        final char[] c = s.toCharArray();
                        contentHandler.characters(c, 0, c.length);
                }
                catch (final SAXException e)
                {
                        throw new IOException(e.getMessage());
                }
        }

        @Override
        protected void finishComment(byte[] comment) throws IOException
        {
                if (lexicalHandler != null)
                {
                        try
                        {
                                String s = string(comment);
                                final char[] c = s.toCharArray();
                                lexicalHandler.comment(c, 0, c.length);
                        }
                        catch (final SAXException e)
                        {
                                throw new IOException(e.getMessage());
                        }
                }
        }

        @Override
        protected void finishPi(byte[] n, byte[] v) throws IOException
        {
                //ignored
        }

        @Override
        protected void atomic(Item i) throws IOException
        {
                //ignored
        }
}

class NSDecl
{
        private final NSDecl parent;
        private Map<String, String> decls;

        public NSDecl(NSDecl parent)
        {
                this.parent = parent;
        }

        public NSDecl getParent()
        {
                return parent;
        }

        public void put(String prefix, String uri)
        {
                if (decls == null)
                {
                        decls = new HashMap<String, String>();
                }
                decls.put(prefix, uri);
        }

        public String get(String prefix)
        {
                String ns = null;
                for (NSDecl c = this; c != null; c = c.parent)
                {
                        if (c.decls != null)
                        {
                                ns = c.decls.get(prefix);
                                if (ns != null)
                                {
                                        break;
                                }
                        }
                }
                return ns != null ? ns : "";
        }
}

Re: [basex-talk] Problem with DOM LS serialization

Michael.Hedenus-EXT＠continental-corporation.com