wbxmlwriter.java

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package org.kxml.wap;

import java.io.*;
import java.util.*;

import org.kxml.*;
import org.kxml.io.*;

//import com.sun.xml.parser.Parser;

/** a class for converting ("binary encoding") XML to WBXML. 
 *  Todo: 
 *  <ul>
 *  <li>Add support for processing instructions 
 *  <li>Add support for tag and attribute tables
 *  <li>Add support for WBXML extensions
 *  </ul>
 */


public class WbxmlWriter extends AbstractXmlWriter {

    Hashtable stringTable = new Hashtable ();

    OutputStream out;

    ByteArrayOutputStream buf = new ByteArrayOutputStream ();
    ByteArrayOutputStream stringTableBuf = new ByteArrayOutputStream ();

    String pending;
    Vector attributes = new Vector ();

    public WbxmlWriter (OutputStream out) throws IOException {

	this.out = out;

	buf = new ByteArrayOutputStream ();
	stringTableBuf = new ByteArrayOutputStream ();

	// ok, write header 

	out.write (0x01); // version
	out.write (0x01); // unknown or missing public identifier
	out.write (0x04); // iso-8859-1
    }


    /** ATTENTION: flush cannot work since Wbxml documents cannot
	need buffering. Thus, this call does nothing. */

    public void flush () {
    }

    public void close () throws IOException {
	writeInt (out, stringTableBuf.size ());
	
	// write StringTable

	out.write (stringTableBuf.toByteArray ());

	// write buf 

	out.write (buf.toByteArray ());

	// ready!

	out.flush ();
    }
    

    public void checkPending (boolean degenerated) throws IOException {
	
	if (pending == null) return;
	
	int len = attributes.size ();

	buf.write 
	    (len == 0 
	     ? (degenerated ? Wbxml.LITERAL : Wbxml.LITERAL_C)
	     : (degenerated ? Wbxml.LITERAL_A : Wbxml.LITERAL_AC));

	writeStrT (pending);
	
	for (int i = 0; i < len;) {
	    buf.write (Wbxml.LITERAL);
	    writeStrT ((String) attributes.elementAt (i++));
	    buf.write (Wbxml.STR_I);
	    writeStrI (buf, (String) attributes.elementAt (i++));
	}

	pending = null;
	attributes.removeAllElements ();
    }


    public void startTag (PrefixMap prefixMap, 
			       String name) throws IOException {

	current = new State (current, prefixMap, name); 
	
	checkPending (false);
	pending = name;
    }


    public void attribute (String name, String value) {
	attributes.addElement (name);
	attributes.addElement (value);
    } 


    public void write (char [] chars, 
		       int start, int len) throws IOException {

	checkPending (false);

	buf.write (Wbxml.STR_I);
	writeStrI (buf, new String (chars, start, len));
    }


    public void endTag () throws IOException {

	current = current.prev;

	if (pending != null) 
	    checkPending (true);
	else
	    buf.write (Wbxml.END);
    }


    /** currently ignored! */

    public void writeLegacy (int type, String data) {
    }

    

    
    // ------------- internal methods --------------------------


    static void writeInt (OutputStream out, int i) throws IOException {
	byte [] buf = new byte [5];
	int idx = 0;

	do {
	    buf [idx++] = (byte) (i & 0x7f);
	    i = i >> 7;
	} while (i != 0);

	while (idx > 1) {
	    out.write (buf [--idx] | 0x80);
	}
	out.write (buf [0]);
    }


    static void writeStrI (OutputStream out, String s) throws IOException {
	for (int i=0; i < s.length (); i++) {
	    out.write ((byte) s.charAt (i));
	}
	out.write (0);
    }

    void writeStrT (String s) throws IOException {

	Integer idx = (Integer) stringTable.get (s);

	if (idx == null) {
	    idx = new Integer (stringTableBuf.size ());
	    stringTable.put (s, idx);
	    writeStrI (stringTableBuf, s);
	    stringTableBuf.flush ();
	}
	
	writeInt (buf, idx.intValue ());
    }
}