/*
 * Copyright 2001-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: XSLTC.java,v 1.57 2004/02/16 22:25:33 minchau Exp $
 */

package com.sun.org.apache.xalan.internal.xsltc.compiler;

import java.io.BufferedOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.Date;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Map;
import java.util.Properties;
import java.util.Vector;
import java.util.jar.JarEntry;
import java.util.jar.JarOutputStream;
import java.util.jar.Manifest;

import com.sun.org.apache.bcel.internal.classfile.JavaClass;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ErrorMsg;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Util;
import com.sun.org.apache.xml.internal.dtm.DTM;

import org.xml.sax.InputSource;
import org.xml.sax.XMLReader;

/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 * @author G. Todd Miller
 * @author Morten Jorgensen
 * @author John Howard (johnh@schemasoft.com)
 */
public final class XSLTC {

    // A reference to the main stylesheet parser object.
    private Parser _parser;

    // A reference to an external XMLReader (SAX parser) passed to us
    private XMLReader _reader = null;

    // A reference to an external SourceLoader (for use with include/import)
    private SourceLoader _loader = null;

    // A reference to the stylesheet being compiled.
    private Stylesheet _stylesheet;

    // Counters used by various classes to generate unique names.
    // private int _variableSerial     = 1;
    private int _modeSerial         = 1;
    private int _stylesheetSerial   = 1;
    private int _stepPatternSerial  = 1;
    private int _helperClassSerial  = 0;
    private int _attributeSetSerial = 0;

    private int[] _numberFieldIndexes;

    // Name index tables
    private int       _nextGType;  // Next available element type
    private Vector    _namesIndex; // Index of all registered QNames
    private Hashtable _elements;   // Hashtable of all registered elements
    private Hashtable _attributes; // Hashtable of all registered attributes

    // Namespace index tables
    private int       _nextNSType; // Next available namespace type
    private Vector    _namespaceIndex; // Index of all registered namespaces
    private Hashtable _namespaces; // Hashtable of all registered namespaces
    private Hashtable _namespacePrefixes;// Hashtable of all registered namespace prefixes


    // All literal text in the stylesheet
    private Vector m_characterData;

    // These define the various methods for outputting the translet
    public static final int FILE_OUTPUT        = 0;
    public static final int JAR_OUTPUT         = 1;
    public static final int BYTEARRAY_OUTPUT   = 2;
    public static final int CLASSLOADER_OUTPUT = 3;
    public static final int BYTEARRAY_AND_FILE_OUTPUT = 4;
    public static final int BYTEARRAY_AND_JAR_OUTPUT  = 5;


    // Compiler options (passed from command line or XSLTC client)
    private boolean _debug = false;      // -x
    private String  _jarFileName = null; // -j <jar-file-name>
    private String  _className = null;   // -o <class-name>
    private String  _packageName = null; // -p <package-name>
    private File    _destDir = null;     // -d <directory-name>
    private int     _outputType = FILE_OUTPUT; // by default

    private Vector  _classes;
    private Vector  _bcelClasses;
    private boolean _callsNodeset = false;
    private boolean _multiDocument = false;
    private boolean _hasIdCall = false;

    /**
     * Set to true if template inlining is requested. Template
     * inlining used to be the default, but we have found that
     * Hotspots does a better job with shorter methods, so the
     * default is *not* to inline now.
     */
    private boolean _templateInlining = false;

    /**
     * XSLTC compiler constructor
     */
    public XSLTC() {
	_parser = new Parser(this);
    }

    /**
     * Only for user by the internal TrAX implementation.
     */
    public Parser getParser() {
        return _parser;
    }

    /**
     * Only for user by the internal TrAX implementation.
     */
    public void setOutputType(int type) {
	_outputType = type;
    }

    /**
     * Only for user by the internal TrAX implementation.
     */
    public Properties getOutputProperties() {
	return _parser.getOutputProperties();
    }

    /**
     * Initializes the compiler to compile a new stylesheet
     */
    public void init() {
	reset();
	_reader = null;
	_classes = new Vector();
	_bcelClasses = new Vector();
    }

    /**
     * Initializes the compiler to produce a new translet
     */
    private void reset() {
	_nextGType      = DTM.NTYPES;
	_elements       = new Hashtable();
	_attributes     = new Hashtable();
	_namespaces     = new Hashtable();
	_namespaces.put("",new Integer(_nextNSType));
	_namesIndex     = new Vector(128);
	_namespaceIndex = new Vector(32);
	_namespacePrefixes = new Hashtable();
        _stylesheet     = null;
	_parser.init();
	//_variableSerial     = 1;
	_modeSerial         = 1;
	_stylesheetSerial   = 1;
	_stepPatternSerial  = 1;
	_helperClassSerial  = 0;
	_attributeSetSerial = 0;
	_multiDocument      = false;
	_hasIdCall          = false;
	_numberFieldIndexes = new int[] {
	    -1, 	// LEVEL_SINGLE
	    -1, 	// LEVEL_MULTIPLE
	    -1		// LEVEL_ANY
	};
    }

    /**
     * Defines an external SourceLoader to provide the compiler with documents
     * referenced in xsl:include/import
     * @param loader The SourceLoader to use for include/import
     */
    public void setSourceLoader(SourceLoader loader) {
	_loader = loader;
    }

    /**
     * Set a flag indicating if templates are to be inlined or not. The
     * default is to do inlining, but this causes problems when the
     * stylesheets have a large number of templates (e.g. branch targets
     * exceeding 64K or a length of a method exceeding 64K).
     */
    public void setTemplateInlining(boolean templateInlining) {
	_templateInlining = templateInlining;
    }

    /**
     * Set the parameters to use to locate the correct <?xml-stylesheet ...?>
     * processing instruction in the case where the input document to the
     * compiler (and parser) is an XML document.
     * @param media The media attribute to be matched. May be null, in which
     * case the prefered templates will be used (i.e. alternate = no).
     * @param title The value of the title attribute to match. May be null.
     * @param charset The value of the charset attribute to match. May be null.
     */
    public void setPIParameters(String media, String title, String charset) {
	_parser.setPIParameters(media, title, charset);
    }

    /**
     * Compiles an XSL stylesheet pointed to by a URL
     * @param url An URL containing the input XSL stylesheet
     */
    public boolean compile(URL url) {
	try {
	    // Open input stream from URL and wrap inside InputSource
	    final InputStream stream = url.openStream();
	    final InputSource input = new InputSource(stream);
	    input.setSystemId(url.toString());
	    return compile(input, _className);
	}
	catch (IOException e) {
	    _parser.reportError(Constants.FATAL, new ErrorMsg(e));
	    return false;
	}
    }

    /**
     * Compiles an XSL stylesheet pointed to by a URL
     * @param url An URL containing the input XSL stylesheet
     * @param name The name to assign to the translet class
     */
    public boolean compile(URL url, String name) {
	try {
	    // Open input stream from URL and wrap inside InputSource
	    final InputStream stream = url.openStream();
	    final InputSource input = new InputSource(stream);
	    input.setSystemId(url.toString());
	    return compile(input, name);
	}
	catch (IOException e) {
	    _parser.reportError(Constants.FATAL, new ErrorMsg(e));
	    return false;
	}
    }

    /**
     * Compiles an XSL stylesheet passed in through an InputStream
     * @param input An InputStream that will pass in the stylesheet contents
     * @param name The name of the translet class to generate
     * @return 'true' if the compilation was successful
     */
    public boolean compile(InputStream stream, String name) {
	final InputSource input = new InputSource(stream);
	input.setSystemId(name); // We have nothing else!!!
	return compile(input, name);
    }

    /**
     * Compiles an XSL stylesheet passed in through an InputStream
     * @param input An InputSource that will pass in the stylesheet contents
     * @param name The name of the translet class to generate - can be null
     * @return 'true' if the compilation was successful
     */
    public boolean compile(InputSource input, String name) {
	try {
	    // Reset globals in case we're called by compile(Vector v);
	    reset();

	    // The systemId may not be set, so we'll have to check the URL
	    String systemId = null;
	    if (input != null) {
	        systemId = input.getSystemId();
	    }

	    // Set the translet class name if not already set
	    if (_className == null) {
		if (name != null) {
		    setClassName(name);
                }
		else if (systemId != null && !systemId.equals("")) {
		    setClassName(Util.baseName(systemId));
                }
                
                // Ensure we have a non-empty class name at this point
                if (_className == null || _className.length() == 0) {
		    setClassName("GregorSamsa"); // default translet name
                }
	    }

	    // Get the root node of the abstract syntax tree
	    SyntaxTreeNode element = null;
	    if (_reader == null) {
		element = _parser.parse(input);
	    }
	    else {
		element = _parser.parse(_reader, input);
	    }

	    // Compile the translet - this is where the work is done!
	    if ((!_parser.errorsFound()) && (element != null)) {
		// Create a Stylesheet element from the root node
		_stylesheet = _parser.makeStylesheet(element);
		_stylesheet.setSourceLoader(_loader);
		_stylesheet.setSystemId(systemId);
		_stylesheet.setParentStylesheet(null);
		_stylesheet.setTemplateInlining(_templateInlining);
		_parser.setCurrentStylesheet(_stylesheet);

		// Create AST under the Stylesheet element (parse & type-check)
		_parser.createAST(_stylesheet);
	    }
	    // Generate the bytecodes and output the translet class(es)
	    if ((!_parser.errorsFound()) && (_stylesheet != null)) {
		_stylesheet.setCallsNodeset(_callsNodeset);
		_stylesheet.setMultiDocument(_multiDocument);
		_stylesheet.setHasIdCall(_hasIdCall);

		// Class synchronization is needed for BCEL
		synchronized (getClass()) {
		    _stylesheet.translate();
		}
	    }
	}
	catch (Exception e) {
	    /*if (_debug)*/ e.printStackTrace();
	    _parser.reportError(Constants.FATAL, new ErrorMsg(e));
	}
	catch (Error e) {
	    if (_debug) e.printStackTrace();
	    _parser.reportError(Constants.FATAL, new ErrorMsg(e));
	}
	finally {
	    _reader = null; // reset this here to be sure it is not re-used
	}
	return !_parser.errorsFound();
    }

    /**
     * Compiles a set of stylesheets pointed to by a Vector of URLs
     * @param stylesheets A Vector containing URLs pointing to the stylesheets
     * @return 'true' if the compilation was successful
     */
    public boolean compile(Vector stylesheets) {
	// Get the number of stylesheets (ie. URLs) in the vector
	final int count = stylesheets.size();

	// Return straight away if the vector is empty
	if (count == 0) return true;

	// Special handling needed if the URL count is one, becuase the
	// _className global must not be reset if it was set explicitly
	if (count == 1) {
	    final Object url = stylesheets.firstElement();
	    if (url instanceof URL)
		return compile((URL)url);
	    else
		return false;
	}
	else {
	    // Traverse all elements in the vector and compile
	    final Enumeration urls = stylesheets.elements();
	    while (urls.hasMoreElements()) {
		_className = null; // reset, so that new name will be computed
		final Object url = urls.nextElement();
		if (url instanceof URL) {
		    if (!compile((URL)url)) return false;
		}
	    }
	}
	return true;
    }

    /**
     * Returns an array of bytecode arrays generated by a compilation.
     * @return JVM bytecodes that represent translet class definition
     */
    public byte[][] getBytecodes() {
	final int count = _classes.size();
	final byte[][] result = new byte[count][1];
	for (int i = 0; i < count; i++)
	    result[i] = (byte[])_classes.elementAt(i);
	return result;
    }

    /**
     * Compiles a stylesheet pointed to by a URL. The result is put in a
     * set of byte arrays. One byte array for each generated class.
     * @param name The name of the translet class to generate
     * @param input An InputSource that will pass in the stylesheet contents
     * @param outputType The output type
     * @return JVM bytecodes that represent translet class definition
     */
    public byte[][] compile(String name, InputSource input, int outputType) {
	_outputType = outputType;
	if (compile(input, name))
	    return getBytecodes();
	else
	    return null;
    }

    /**
     * Compiles a stylesheet pointed to by a URL. The result is put in a
     * set of byte arrays. One byte array for each generated class.
     * @param name The name of the translet class to generate
     * @param input An InputSource that will pass in the stylesheet contents
     * @return JVM bytecodes that represent translet class definition
     */
    public byte[][] compile(String name, InputSource input) {
        return compile(name, input, BYTEARRAY_OUTPUT);
    }

    /**
     * Set the XMLReader to use for parsing the next input stylesheet
     * @param reader XMLReader (SAX2 parser) to use
     */
    public void setXMLReader(XMLReader reader) {
	_reader = reader;
    }

    /**
     * Get the XMLReader to use for parsing the next input stylesheet
     */
    public XMLReader getXMLReader() {
	return _reader ;
    }

    /**
     * Get a Vector containing all compile error messages
     * @return A Vector containing all compile error messages
     */
    public Vector getErrors() {
	return _parser.getErrors();
    }

    /**
     * Get a Vector containing all compile warning messages
     * @return A Vector containing all compile error messages
     */
    public Vector getWarnings() {
	return _parser.getWarnings();
    }

    /**
     * Print all compile error messages to standard output
     */
    public void printErrors() {
	_parser.printErrors();
    }

    /**
     * Print all compile warning messages to standard output
     */
    public void printWarnings() {
	_parser.printWarnings();
    }

    /**
     * This method is called by the XPathParser when it encounters a call
     * to the document() function. Affects the DOM used by the translet.
     */
    protected void setMultiDocument(boolean flag) {
	_multiDocument = flag;
    }

    public boolean isMultiDocument() {
	return _multiDocument;
    }

    /**
     * This method is called by the XPathParser when it encounters a call
     * to the nodeset() extension function. Implies multi document.
     */
    protected void setCallsNodeset(boolean flag) {
	if (flag) setMultiDocument(flag);
	_callsNodeset = flag;
    }

    public boolean callsNodeset() {
	return _callsNodeset;
    }

    protected void setHasIdCall(boolean flag) {
    	_hasIdCall = flag;
    }

    public boolean hasIdCall() {
    	return _hasIdCall;
    }

    /**
     * Set the class name for the generated translet. This class name is
     * overridden if multiple stylesheets are compiled in one go using the
     * compile(Vector urls) method.
     * @param className The name to assign to the translet class
     */
    public void setClassName(String className) {
	final String base  = Util.baseName(className);
	final String noext = Util.noExtName(base);
	String name  = Util.toJavaName(noext);

	if (_packageName == null)
	    _className = name;
	else
	    _className = _packageName + '.' + name;
    }

    /**
     * Get the class name for the generated translet.
     */
    public String getClassName() {
	return _className;
    }

    /**
     * Convert for Java class name of local system file name.
     * (Replace '.' with '/' on UNIX and replace '.' by '\' on Windows/DOS.)
     */
    private String classFileName(final String className) {
	return className.replace('.', File.separatorChar) + ".class";
    }

    /**
     * Generate an output File object to send the translet to
     */
    private File getOutputFile(String className) {
	if (_destDir != null)
	    return new File(_destDir, classFileName(className));
	else
	    return new File(classFileName(className));
    }

    /**
     * Set the destination directory for the translet.
     * The current working directory will be used by default.
     */
    public boolean setDestDirectory(String dstDirName) {
	final File dir = new File(dstDirName);
	if (dir.exists() || dir.mkdirs()) {
	    _destDir = dir;
	    return true;
	}
	else {
	    _destDir = null;
	    return false;
	}
    }

    /**
     * Set an optional package name for the translet and auxiliary classes
     */
    public void setPackageName(String packageName) {
	_packageName = packageName;
	if (_className != null) setClassName(_className);
    }

    /**
     * Set the name of an optional JAR-file to dump the translet and
     * auxiliary classes to
     */
    public void setJarFileName(String jarFileName) {
	final String JAR_EXT = ".jar";
	if (jarFileName.endsWith(JAR_EXT))
	    _jarFileName = jarFileName;
	else
	    _jarFileName = jarFileName + JAR_EXT;
	_outputType = JAR_OUTPUT;
    }

    public String getJarFileName() {
	return _jarFileName;
    }

    /**
     * Set the top-level stylesheet
     */
    public void setStylesheet(Stylesheet stylesheet) {
	if (_stylesheet == null) _stylesheet = stylesheet;
    }

    /**
     * Returns the top-level stylesheet
     */
    public Stylesheet getStylesheet() {
	return _stylesheet;
    }

    /**
     * Registers an attribute and gives it a type so that it can be mapped to
     * DOM attribute types at run-time.
     */
    public int registerAttribute(QName name) {
	Integer code = (Integer)_attributes.get(name.toString());
	if (code == null) {
	    code = new Integer(_nextGType++);
	    _attributes.put(name.toString(), code);
	    final String uri = name.getNamespace();
	    final String local = "@"+name.getLocalPart();
	    if ((uri != null) && (!uri.equals("")))
		_namesIndex.addElement(uri+":"+local);
	    else
		_namesIndex.addElement(local);
	    if (name.getLocalPart().equals("*")) {
		registerNamespace(name.getNamespace());
	    }
	}
	return code.intValue();
    }

    /**
     * Registers an element and gives it a type so that it can be mapped to
     * DOM element types at run-time.
     */
    public int registerElement(QName name) {
	// Register element (full QName)
	Integer code = (Integer)_elements.get(name.toString());
	if (code == null) {
	    _elements.put(name.toString(), code = new Integer(_nextGType++));
	    _namesIndex.addElement(name.toString());
	}
	if (name.getLocalPart().equals("*")) {
	    registerNamespace(name.getNamespace());
	}
	return code.intValue();
    }

     /** 
      * Registers a namespace prefix and gives it a type so that it can be mapped to
      * DOM namespace types at run-time.
      */
  
    public int registerNamespacePrefix(QName name) {
    
    Integer code = (Integer)_namespacePrefixes.get(name.toString());
    if (code == null) {   
        code = new Integer(_nextGType++);
        _namespacePrefixes.put(name.toString(), code); 
        final String uri = name.getNamespace();
        if ((uri != null) && (!uri.equals(""))){
            // namespace::ext2:ped2 will be made empty in TypedNamespaceIterator
            _namesIndex.addElement("?"); 
        } else{        
           _namesIndex.addElement("?"+name.getLocalPart());        
        }
    }   
    return code.intValue();
    }

    /**
     * Registers a namespace and gives it a type so that it can be mapped to
     * DOM namespace types at run-time.
     */
    public int registerNamespace(String namespaceURI) {
	Integer code = (Integer)_namespaces.get(namespaceURI);
	if (code == null) {
	    code = new Integer(_nextNSType++);
	    _namespaces.put(namespaceURI,code);
	    _namespaceIndex.addElement(namespaceURI);
	}
	return code.intValue();
    }

    public int nextModeSerial() {
	return _modeSerial++;
    }

    public int nextStylesheetSerial() {
	return _stylesheetSerial++;
    }

    public int nextStepPatternSerial() {
	return _stepPatternSerial++;
    }

    public int[] getNumberFieldIndexes() {
	return _numberFieldIndexes;
    }

    public int nextHelperClassSerial() {
	return _helperClassSerial++;
    }

    public int nextAttributeSetSerial() {
	return _attributeSetSerial++;
    }

    public Vector getNamesIndex() {
	return _namesIndex;
    }

    public Vector getNamespaceIndex() {
	return _namespaceIndex;
    }

    /**
     * Returns a unique name for every helper class needed to
     * execute a translet.
     */
    public String getHelperClassName() {
	return getClassName() + '$' + _helperClassSerial++;
    }

    public void dumpClass(JavaClass clazz) {

	if (_outputType == FILE_OUTPUT ||
	    _outputType == BYTEARRAY_AND_FILE_OUTPUT)
	{
	    File outFile = getOutputFile(clazz.getClassName());
	    String parentDir = outFile.getParent();
	    if (parentDir != null) {
	      	File parentFile = new File(parentDir);
	      	if (!parentFile.exists())
	            parentFile.mkdirs();
	    }
	}

	try {
	    switch (_outputType) {
	    case FILE_OUTPUT:
		clazz.dump(
		    new BufferedOutputStream(
			new FileOutputStream(
			    getOutputFile(clazz.getClassName()))));
		break;
	    case JAR_OUTPUT:
		_bcelClasses.addElement(clazz);
		break;
	    case BYTEARRAY_OUTPUT:
	    case BYTEARRAY_AND_FILE_OUTPUT:
	    case BYTEARRAY_AND_JAR_OUTPUT:
	    case CLASSLOADER_OUTPUT:
		ByteArrayOutputStream out = new ByteArrayOutputStream(2048);
		clazz.dump(out);
		_classes.addElement(out.toByteArray());

		if (_outputType == BYTEARRAY_AND_FILE_OUTPUT)
		  clazz.dump(new BufferedOutputStream(
			new FileOutputStream(getOutputFile(clazz.getClassName()))));
		else if (_outputType == BYTEARRAY_AND_JAR_OUTPUT)
		  _bcelClasses.addElement(clazz);

		break;
	    }
	}
	catch (Exception e) {
	    e.printStackTrace();
	}
    }

    /**
     * File separators are converted to forward slashes for ZIP files.
     */
    private String entryName(File f) throws IOException {
	return f.getName().replace(File.separatorChar, '/');
    }

    /**
     * Generate output JAR-file and packages
     */
    public void outputToJar() throws IOException {
	// create the manifest
	final Manifest manifest = new Manifest();
	final java.util.jar.Attributes atrs = manifest.getMainAttributes();
	atrs.put(java.util.jar.Attributes.Name.MANIFEST_VERSION,"1.2");

	final Map map = manifest.getEntries();
	// create manifest
	Enumeration classes = _bcelClasses.elements();
	final String now = (new Date()).toString();
	final java.util.jar.Attributes.Name dateAttr =
	    new java.util.jar.Attributes.Name("Date");
	while (classes.hasMoreElements()) {
	    final JavaClass clazz = (JavaClass)classes.nextElement();
	    final String className = clazz.getClassName().replace('.','/');
	    final java.util.jar.Attributes attr = new java.util.jar.Attributes();
	    attr.put(dateAttr, now);
	    map.put(className+".class", attr);
	}

	final File jarFile = new File(_destDir, _jarFileName);
	final JarOutputStream jos =
	    new JarOutputStream(new FileOutputStream(jarFile), manifest);
	classes = _bcelClasses.elements();
	while (classes.hasMoreElements()) {
	    final JavaClass clazz = (JavaClass)classes.nextElement();
	    final String className = clazz.getClassName().replace('.','/');
	    jos.putNextEntry(new JarEntry(className+".class"));
	    final ByteArrayOutputStream out = new ByteArrayOutputStream(2048);
	    clazz.dump(out); // dump() closes it's output stream
	    out.writeTo(jos);
	}
	jos.close();
    }

    /**
     * Turn debugging messages on/off
     */
    public void setDebug(boolean debug) {
	_debug = debug;
    }

    /**
     * Get current debugging message setting
     */
    public boolean debug() {
	return _debug;
    }


    /**
     * Retrieve a string representation of the character data to be stored
     * in the translet as a <code>char[]</code>.  There may be more than
     * one such array required.
     * @param index The index of the <code>char[]</code>.  Zero-based.
     * @return String The character data to be stored in the corresponding
     *               <code>char[]</code>.
     */
    public String getCharacterData(int index) {
        return ((StringBuffer) m_characterData.elementAt(index)).toString();
    }

    /**
     * Get the number of char[] arrays, thus far, that will be created to
     * store literal text in the stylesheet.
     */
    public int getCharacterDataCount() {
        return (m_characterData != null) ? m_characterData.size() : 0;
    }

    /**
     * Add literal text to char arrays that will be used to store character
     * data in the stylesheet.
     * @param newData String data to be added to char arrays.
     *                Pre-condition:  <code>newData.length() ≤ 21845</code>
     * @return int offset at which character data will be stored
     */
    public int addCharacterData(String newData) {
        StringBuffer currData;
        if (m_characterData == null) {
            m_characterData = new Vector();
            currData = new StringBuffer();
            m_characterData.addElement(currData);
        } else {
            currData = (StringBuffer) m_characterData
                                           .elementAt(m_characterData.size()-1);
        }

        // Character data could take up to three-times as much space when
        // written to the class file as UTF-8.  The maximum size for a
        // constant is 65535/3.  If we exceed that,
        // (We really should use some "bin packing".)
        if (newData.length() + currData.length() > 21845) {
            currData = new StringBuffer();
            m_characterData.addElement(currData);
        }

        int newDataOffset = currData.length();
        currData.append(newData);

        return newDataOffset;
    }
}