Package javax.swing.text

Source Code of javax.swing.text.DefaultStyledDocument$ChangeUpdateRunnable

/*
* @(#)DefaultStyledDocument.java  1.129 08/03/05
*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package javax.swing.text;

import java.awt.Color;
import java.awt.Component;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.font.TextAttribute;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.WeakReference;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.List;
import java.util.Map;
import java.util.Stack;
import java.util.Vector;
import java.util.ArrayList;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import javax.swing.Icon;
import javax.swing.event.*;
import javax.swing.undo.AbstractUndoableEdit;
import javax.swing.undo.CannotRedoException;
import javax.swing.undo.CannotUndoException;
import javax.swing.undo.UndoableEdit;
import javax.swing.SwingUtilities;
import sun.swing.SwingUtilities2;
import static sun.swing.SwingUtilities2.IMPLIED_CR;

/**
* A document that can be marked up with character and paragraph
* styles in a manner similar to the Rich Text Format.  The element
* structure for this document represents style crossings for
* style runs.  These style runs are mapped into a paragraph element
* structure (which may reside in some other structure).  The
* style runs break at paragraph boundaries since logical styles are
* assigned to paragraph boundaries.
* <p>
* <strong>Warning:</strong>
* Serialized objects of this class will not be compatible with
* future Swing releases. The current serialization support is
* appropriate for short term storage or RMI between applications running
* the same version of Swing.  As of 1.4, support for long term storage
* of all JavaBeans<sup><font size="-2">TM</font></sup>
* has been added to the <code>java.beans</code> package.
* Please see {@link java.beans.XMLEncoder}.
*
* @author  Timothy Prinzing
* @version 1.129 03/05/08
* @see     Document
* @see     AbstractDocument
*/
public class DefaultStyledDocument extends AbstractDocument implements StyledDocument {

    /**
     * Constructs a styled document.
     *
     * @param c  the container for the content
     * @param styles resources and style definitions which may
     *  be shared across documents
     */
    public DefaultStyledDocument(Content c, StyleContext styles) {
  super(c, styles);
  listeningStyles = new Vector();
  buffer = new ElementBuffer(createDefaultRoot());
  Style defaultStyle = styles.getStyle(StyleContext.DEFAULT_STYLE);
  setLogicalStyle(0, defaultStyle);
    }

    /**
     * Constructs a styled document with the default content
     * storage implementation and a shared set of styles.
     *
     * @param styles the styles
     */
    public DefaultStyledDocument(StyleContext styles) {
  this(new GapContent(BUFFER_SIZE_DEFAULT), styles);
    }

    /**
     * Constructs a default styled document.  This buffers
     * input content by a size of <em>BUFFER_SIZE_DEFAULT</em>
     * and has a style context that is scoped by the lifetime
     * of the document and is not shared with other documents.
     */
    public DefaultStyledDocument() {
  this(new GapContent(BUFFER_SIZE_DEFAULT), new StyleContext());
    }

    /**
     * Gets the default root element.
     *
     * @return the root
     * @see Document#getDefaultRootElement
     */
    public Element getDefaultRootElement() {
  return buffer.getRootElement();
    }

    /**
     * Initialize the document to reflect the given element
     * structure (i.e. the structure reported by the
     * <code>getDefaultRootElement</code> method.  If the
     * document contained any data it will first be removed.
     */
    protected void create(ElementSpec[] data) {
  try {
      if (getLength() != 0) {
    remove(0, getLength());
      }
      writeLock();

      // install the content
      Content c = getContent();
      int n = data.length;
      StringBuffer sb = new StringBuffer();
      for (int i = 0; i < n; i++) {
    ElementSpec es = data[i];
    if (es.getLength() > 0) {
        sb.append(es.getArray(), es.getOffset(),  es.getLength());
    }
      }
      UndoableEdit cEdit = c.insertString(0, sb.toString());

      // build the event and element structure
      int length = sb.length();
      DefaultDocumentEvent evnt =
    new DefaultDocumentEvent(0, length, DocumentEvent.EventType.INSERT);
      evnt.addEdit(cEdit);
      buffer.create(length, data, evnt);

      // update bidi (possibly)
      super.insertUpdate(evnt, null);

      // notify the listeners
      evnt.end();
      fireInsertUpdate(evnt);
      fireUndoableEditUpdate(new UndoableEditEvent(this, evnt));
  } catch (BadLocationException ble) {
      throw new StateInvariantError("problem initializing");
  } finally {
      writeUnlock();
  }
 
    }

    /**
     * Inserts new elements in bulk.  This is useful to allow
     * parsing with the document in an unlocked state and
     * prepare an element structure modification.  This method
     * takes an array of tokens that describe how to update an
     * element structure so the time within a write lock can
     * be greatly reduced in an asynchronous update situation.    
     * <p>
     * This method is thread safe, although most Swing methods
     * are not. Please see
     * <A HREF="http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html">How
     * to Use Threads</A> for more information.    
     *
     * @param offset the starting offset >= 0
     * @param data the element data
     * @exception BadLocationException for an invalid starting offset
     */
    protected void insert(int offset, ElementSpec[] data) throws BadLocationException {
  if (data == null || data.length == 0) {
      return;
  }

  try {
      writeLock();

      // install the content
      Content c = getContent();
      int n = data.length;
      StringBuffer sb = new StringBuffer();
      for (int i = 0; i < n; i++) {
    ElementSpec es = data[i];
    if (es.getLength() > 0) {
        sb.append(es.getArray(), es.getOffset(),  es.getLength());
    }
      }
      if (sb.length() == 0) {
    // Nothing to insert, bail.
    return;
      }
      UndoableEdit cEdit = c.insertString(offset, sb.toString());

      // create event and build the element structure
      int length = sb.length();
      DefaultDocumentEvent evnt =
    new DefaultDocumentEvent(offset, length, DocumentEvent.EventType.INSERT);
      evnt.addEdit(cEdit);
      buffer.insert(offset, length, data, evnt);
     
      // update bidi (possibly)
      super.insertUpdate(evnt, null);

      // notify the listeners
      evnt.end();
      fireInsertUpdate(evnt);
      fireUndoableEditUpdate(new UndoableEditEvent(this, evnt));
  } finally {
      writeUnlock();
  }
    }

    /**
     * Adds a new style into the logical style hierarchy.  Style attributes
     * resolve from bottom up so an attribute specified in a child
     * will override an attribute specified in the parent.
     *
     * @param nm   the name of the style (must be unique within the
     *   collection of named styles).  The name may be null if the style
     *   is unnamed, but the caller is responsible
     *   for managing the reference returned as an unnamed style can't
     *   be fetched by name.  An unnamed style may be useful for things
     *   like character attribute overrides such as found in a style
     *   run.
     * @param parent the parent style.  This may be null if unspecified
     *   attributes need not be resolved in some other style.
     * @return the style
     */
    public Style addStyle(String nm, Style parent) {
  StyleContext styles = (StyleContext) getAttributeContext();
  return styles.addStyle(nm, parent);
    }

    /**
     * Removes a named style previously added to the document. 
     *
     * @param nm  the name of the style to remove
     */
    public void removeStyle(String nm) {
  StyleContext styles = (StyleContext) getAttributeContext();
  styles.removeStyle(nm);
    }

    /**
     * Fetches a named style previously added.
     *
     * @param nm  the name of the style
     * @return the style
     */
    public Style getStyle(String nm) {
  StyleContext styles = (StyleContext) getAttributeContext();
  return styles.getStyle(nm);
    }


    /**
     * Fetches the list of of style names.
     *
     * @return all the style names
     */
    public Enumeration<?> getStyleNames() {
  return ((StyleContext) getAttributeContext()).getStyleNames();
    }

    /**
     * Sets the logical style to use for the paragraph at the
     * given position.  If attributes aren't explicitly set
     * for character and paragraph attributes they will resolve
     * through the logical style assigned to the paragraph, which
     * in turn may resolve through some hierarchy completely
     * independent of the element hierarchy in the document.
     * <p>
     * This method is thread safe, although most Swing methods
     * are not. Please see
     * <A HREF="http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html">How
     * to Use Threads</A> for more information.    
     *
     * @param pos the offset from the start of the document >= 0
     * @param s  the logical style to assign to the paragraph, null if none
     */
    public void setLogicalStyle(int pos, Style s) {
  Element paragraph = getParagraphElement(pos);
  if ((paragraph != null) && (paragraph instanceof AbstractElement)) {
      try {
    writeLock();
    StyleChangeUndoableEdit edit = new StyleChangeUndoableEdit((AbstractElement)paragraph, s);
    ((AbstractElement)paragraph).setResolveParent(s);
    int p0 = paragraph.getStartOffset();
    int p1 = paragraph.getEndOffset();
    DefaultDocumentEvent e =
      new DefaultDocumentEvent(p0, p1 - p0, DocumentEvent.EventType.CHANGE);
    e.addEdit(edit);
    e.end();
    fireChangedUpdate(e);
    fireUndoableEditUpdate(new UndoableEditEvent(this, e));
      } finally {
    writeUnlock();
      }
  }
    }

    /**
     * Fetches the logical style assigned to the paragraph
     * represented by the given position.
     *
     * @param p the location to translate to a paragraph
     *  and determine the logical style assigned >= 0.  This
     *  is an offset from the start of the document.
     * @return the style, null if none
     */
    public Style getLogicalStyle(int p) {
  Style s = null;
  Element paragraph = getParagraphElement(p);
  if (paragraph != null) {
      AttributeSet a = paragraph.getAttributes();
      AttributeSet parent = a.getResolveParent();
      if (parent instanceof Style) {
    s = (Style) parent;
      }
  }
  return s;
    }

    /**
     * Sets attributes for some part of the document.
     * A write lock is held by this operation while changes
     * are being made, and a DocumentEvent is sent to the listeners
     * after the change has been successfully completed.
     * <p>
     * This method is thread safe, although most Swing methods
     * are not. Please see
     * <A HREF="http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html">How
     * to Use Threads</A> for more information.    
     *
     * @param offset the offset in the document >= 0
     * @param length the length >= 0
     * @param s the attributes
     * @param replace true if the previous attributes should be replaced
     *  before setting the new attributes
     */
    public void setCharacterAttributes(int offset, int length, AttributeSet s, boolean replace) {
        if (length == 0) {
            return;
        }
  try {
      writeLock();
      DefaultDocumentEvent changes =
    new DefaultDocumentEvent(offset, length, DocumentEvent.EventType.CHANGE);

      // split elements that need it
      buffer.change(offset, length, changes);

      AttributeSet sCopy = s.copyAttributes();

      // PENDING(prinz) - this isn't a very efficient way to iterate
      int lastEnd = Integer.MAX_VALUE;
      for (int pos = offset; pos < (offset + length); pos = lastEnd) {
    Element run = getCharacterElement(pos);
    lastEnd = run.getEndOffset();
                if (pos == lastEnd) {
                    // offset + length beyond length of document, bail.
                    break;
                }
    MutableAttributeSet attr = (MutableAttributeSet) run.getAttributes();
    changes.addEdit(new AttributeUndoableEdit(run, sCopy, replace));
    if (replace) {
        attr.removeAttributes(attr);
    }
    attr.addAttributes(s);
      }
      changes.end();
      fireChangedUpdate(changes);
      fireUndoableEditUpdate(new UndoableEditEvent(this, changes));
  } finally {
      writeUnlock();
  }

    }

    /**
     * Sets attributes for a paragraph.
     * <p>
     * This method is thread safe, although most Swing methods
     * are not. Please see
     * <A HREF="http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html">How
     * to Use Threads</A> for more information.    
     *
     * @param offset the offset into the paragraph >= 0
     * @param length the number of characters affected >= 0
     * @param s the attributes
     * @param replace whether to replace existing attributes, or merge them
     */
    public void setParagraphAttributes(int offset, int length, AttributeSet s,
               boolean replace) {
  try {
      writeLock();
      DefaultDocumentEvent changes =
    new DefaultDocumentEvent(offset, length, DocumentEvent.EventType.CHANGE);

      AttributeSet sCopy = s.copyAttributes();

      // PENDING(prinz) - this assumes a particular element structure
      Element section = getDefaultRootElement();
      int index0 = section.getElementIndex(offset);
      int index1 = section.getElementIndex(offset + ((length > 0) ? length - 1 : 0));
            boolean isI18N = Boolean.TRUE.equals(getProperty(I18NProperty));
            boolean hasRuns = false;
      for (int i = index0; i <= index1; i++) {
    Element paragraph = section.getElement(i);
    MutableAttributeSet attr = (MutableAttributeSet) paragraph.getAttributes();
    changes.addEdit(new AttributeUndoableEdit(paragraph, sCopy, replace));
    if (replace) {
        attr.removeAttributes(attr);
    }
    attr.addAttributes(s);
                if (isI18N && !hasRuns) {
                    hasRuns = (attr.getAttribute(TextAttribute.RUN_DIRECTION) != null);
                }
      }

            if (hasRuns) {
                updateBidi( changes );
            }

      changes.end();
      fireChangedUpdate(changes);
      fireUndoableEditUpdate(new UndoableEditEvent(this, changes));
  } finally {
      writeUnlock();
  }
    }

    /**
     * Gets the paragraph element at the offset <code>pos</code>.
     * A paragraph consists of at least one child Element, which is usually
     * a leaf.
     *
     * @param pos the starting offset >= 0
     * @return the element
     */
    public Element getParagraphElement(int pos) {
  Element e = null;
  for (e = getDefaultRootElement(); ! e.isLeaf(); ) {
      int index = e.getElementIndex(pos);
      e = e.getElement(index);
  }
  if(e != null)
      return e.getParentElement();
  return e;
    }

    /**
     * Gets a character element based on a position.
     *
     * @param pos the position in the document >= 0
     * @return the element
     */
    public Element getCharacterElement(int pos) {
  Element e = null;
  for (e = getDefaultRootElement(); ! e.isLeaf(); ) {
      int index = e.getElementIndex(pos);
      e = e.getElement(index);
  }
  return e;
    }

    // --- local methods -------------------------------------------------

    /**
     * Updates document structure as a result of text insertion.  This
     * will happen within a write lock.  This implementation simply
     * parses the inserted content for line breaks and builds up a set
     * of instructions for the element buffer.
     *
     * @param chng a description of the document change
     * @param attr the attributes
     */
    protected void insertUpdate(DefaultDocumentEvent chng, AttributeSet attr) {
  int offset = chng.getOffset();
  int length = chng.getLength();
  if (attr == null) {
      attr = SimpleAttributeSet.EMPTY;
  }

  // Paragraph attributes should come from point after insertion.
  // You really only notice this when inserting at a paragraph
  // boundary.
  Element paragraph = getParagraphElement(offset + length);
  AttributeSet pattr = paragraph.getAttributes();
  // Character attributes should come from actual insertion point.
  Element pParagraph = getParagraphElement(offset);
  Element run = pParagraph.getElement(pParagraph.getElementIndex
              (offset));
  int endOffset = offset + length;
  boolean insertingAtBoundry = (run.getEndOffset() == endOffset);
  AttributeSet cattr = run.getAttributes();

  try {
      Segment s = new Segment();
      Vector parseBuffer = new Vector();
      ElementSpec lastStartSpec = null;
      boolean insertingAfterNewline = false;
      short lastStartDirection = ElementSpec.OriginateDirection;
      // Check if the previous character was a newline.
      if (offset > 0) {
    getText(offset - 1, 1, s);
    if (s.array[s.offset] == '\n') {
        // Inserting after a newline.
        insertingAfterNewline = true;
        lastStartDirection = createSpecsForInsertAfterNewline
                (paragraph, pParagraph, pattr, parseBuffer,
           offset, endOffset);
        for(int counter = parseBuffer.size() - 1; counter >= 0;
      counter--) {
      ElementSpec spec = (ElementSpec)parseBuffer.
                          elementAt(counter);
      if(spec.getType() == ElementSpec.StartTagType) {
          lastStartSpec = spec;
          break;
      }
        }
    }
      }
      // If not inserting after a new line, pull the attributes for
      // new paragraphs from the paragraph under the insertion point.
      if(!insertingAfterNewline)
    pattr = pParagraph.getAttributes();

      getText(offset, length, s);
      char[] txt = s.array;
      int n = s.offset + s.count;
      int lastOffset = s.offset;

      for (int i = s.offset; i < n; i++) {
    if (txt[i] == '\n') {
        int breakOffset = i + 1;
        parseBuffer.addElement(
                        new ElementSpec(attr, ElementSpec.ContentType,
                 breakOffset - lastOffset));
        parseBuffer.addElement(
                        new ElementSpec(null, ElementSpec.EndTagType));
        lastStartSpec = new ElementSpec(pattr, ElementSpec.
               StartTagType);
        parseBuffer.addElement(lastStartSpec);
        lastOffset = breakOffset;
    }
      }
      if (lastOffset < n) {
    parseBuffer.addElement(
                    new ElementSpec(attr, ElementSpec.ContentType,
             n - lastOffset));
      }

      ElementSpec first = (ElementSpec) parseBuffer.firstElement();

      int docLength = getLength();

      // Check for join previous of first content.
      if(first.getType() == ElementSpec.ContentType &&
         cattr.isEqual(attr)) {
    first.setDirection(ElementSpec.JoinPreviousDirection);
      }

      // Do a join fracture/next for last start spec if necessary.
      if(lastStartSpec != null) {
    if(insertingAfterNewline) {
        lastStartSpec.setDirection(lastStartDirection);
    }
    // Join to the fracture if NOT inserting at the end
    // (fracture only happens when not inserting at end of
    // paragraph).
    else if(pParagraph.getEndOffset() != endOffset) {
        lastStartSpec.setDirection(ElementSpec.
                 JoinFractureDirection);
    }
    // Join to next if parent of pParagraph has another
    // element after pParagraph, and it isn't a leaf.
    else {
        Element parent = pParagraph.getParentElement();
        int pParagraphIndex = parent.getElementIndex(offset);
        if((pParagraphIndex + 1) < parent.getElementCount() &&
           !parent.getElement(pParagraphIndex + 1).isLeaf()) {
      lastStartSpec.setDirection(ElementSpec.
               JoinNextDirection);
        }
    }
      }

      // Do a JoinNext for last spec if it is content, it doesn't
      // already have a direction set, no new paragraphs have been
      // inserted or a new paragraph has been inserted and its join
      // direction isn't originate, and the element at endOffset
      // is a leaf.
      if(insertingAtBoundry && endOffset < docLength) {
    ElementSpec last = (ElementSpec) parseBuffer.lastElement();
    if(last.getType() == ElementSpec.ContentType &&
       last.getDirection() != ElementSpec.JoinPreviousDirection &&
       ((lastStartSpec == null && (paragraph == pParagraph ||
                 insertingAfterNewline)) ||
        (lastStartSpec != null && lastStartSpec.getDirection() !=
         ElementSpec.OriginateDirection))) {
        Element nextRun = paragraph.getElement(paragraph.
             getElementIndex(endOffset));
        // Don't try joining to a branch!
        if(nextRun.isLeaf() &&
           attr.isEqual(nextRun.getAttributes())) {
      last.setDirection(ElementSpec.JoinNextDirection);
        }
    }
      }
      // If not inserting at boundary and there is going to be a
      // fracture, then can join next on last content if cattr
      // matches the new attributes.
      else if(!insertingAtBoundry && lastStartSpec != null &&
        lastStartSpec.getDirection() ==
        ElementSpec.JoinFractureDirection) {
    ElementSpec last = (ElementSpec) parseBuffer.lastElement();
    if(last.getType() == ElementSpec.ContentType &&
       last.getDirection() != ElementSpec.JoinPreviousDirection &&
       attr.isEqual(cattr)) {
        last.setDirection(ElementSpec.JoinNextDirection);
    }
      }

      // Check for the composed text element. If it is, merge the character attributes
      // into this element as well.
      if (Utilities.isComposedTextAttributeDefined(attr)) {
                MutableAttributeSet mattr = (MutableAttributeSet) attr;
          mattr.addAttributes(cattr);
         mattr.addAttribute(AbstractDocument.ElementNameAttribute,
                                  AbstractDocument.ContentElementName);

                // Assure that the composed text element is named properly
                // and doesn't have the CR attribute defined.
          mattr.addAttribute(StyleConstants.NameAttribute,
                                   AbstractDocument.ContentElementName);
                if (mattr.isDefined(IMPLIED_CR)) {
                    mattr.removeAttribute(IMPLIED_CR);
                }
      }

      ElementSpec[] spec = new ElementSpec[parseBuffer.size()];
      parseBuffer.copyInto(spec);
      buffer.insert(offset, length, spec, chng);
  } catch (BadLocationException bl) {
  }

        super.insertUpdate( chng, attr );
    }

    /**
     * This is called by insertUpdate when inserting after a new line.
     * It generates, in <code>parseBuffer</code>, ElementSpecs that will
     * position the stack in <code>paragraph</code>.<p>
     * It returns the direction the last StartSpec should have (this don't
     * necessarily create the last start spec).
     */
    short createSpecsForInsertAfterNewline(Element paragraph,
              Element pParagraph, AttributeSet pattr, Vector parseBuffer,
             int offset, int endOffset) {
  // Need to find the common parent of pParagraph and paragraph.
  if(paragraph.getParentElement() == pParagraph.getParentElement()) {
      // The simple (and common) case that pParagraph and
      // paragraph have the same parent.
      ElementSpec spec = new ElementSpec(pattr, ElementSpec.EndTagType);
      parseBuffer.addElement(spec);
      spec = new ElementSpec(pattr, ElementSpec.StartTagType);
      parseBuffer.addElement(spec);
      if(pParagraph.getEndOffset() != endOffset)
    return ElementSpec.JoinFractureDirection;

      Element parent = pParagraph.getParentElement();
      if((parent.getElementIndex(offset) + 1) < parent.getElementCount())
    return ElementSpec.JoinNextDirection;
  }
  else {
      // Will only happen for text with more than 2 levels.
      // Find the common parent of a paragraph and pParagraph
      Vector leftParents = new Vector();
      Vector rightParents = new Vector();
      Element e = pParagraph;
      while(e != null) {
    leftParents.addElement(e);
    e = e.getParentElement();
      }
      e = paragraph;
      int leftIndex = -1;
      while(e != null && (leftIndex = leftParents.indexOf(e)) == -1) {
    rightParents.addElement(e);
    e = e.getParentElement();
      }
      if(e != null) {
    // e identifies the common parent.
    // Build the ends.
    for(int counter = 0; counter < leftIndex;
        counter++) {
        parseBuffer.addElement(new ElementSpec
                (null, ElementSpec.EndTagType));
    }
    // And the starts.
    ElementSpec spec = null;
    for(int counter = rightParents.size() - 1;
        counter >= 0; counter--) {
        spec = new ElementSpec(((Element)rightParents.
           elementAt(counter)).getAttributes(),
           ElementSpec.StartTagType);
        if(counter > 0)
      spec.setDirection(ElementSpec.JoinNextDirection);
        parseBuffer.addElement(spec);
    }
    // If there are right parents, then we generated starts
    // down the right subtree and there will be an element to
    // join to.
    if(rightParents.size() > 0)
        return ElementSpec.JoinNextDirection;
    // No right subtree, e.getElement(endOffset) is a
    // leaf. There will be a facture.
    return ElementSpec.JoinFractureDirection;
      }
      // else: Could throw an exception here, but should never get here!
  }
  return ElementSpec.OriginateDirection;
    }

    /**
     * Updates document structure as a result of text removal.
     *
     * @param chng a description of the document change
     */
    protected void removeUpdate(DefaultDocumentEvent chng) {
        super.removeUpdate(chng);
  buffer.remove(chng.getOffset(), chng.getLength(), chng);
    }

    /**
     * Creates the root element to be used to represent the
     * default document structure.
     *
     * @return the element base
     */
    protected AbstractElement createDefaultRoot() {
  // grabs a write-lock for this initialization and
  // abandon it during initialization so in normal
  // operation we can detect an illegitimate attempt
  // to mutate attributes.
  writeLock();
  BranchElement section = new SectionElement();
  BranchElement paragraph = new BranchElement(section, null);

  LeafElement brk = new LeafElement(paragraph, null, 0, 1);
  Element[] buff = new Element[1];
  buff[0] = brk;
  paragraph.replace(0, 0, buff);

  buff[0] = paragraph;
  section.replace(0, 0, buff);
  writeUnlock();
  return section;
    }

    /**
     * Gets the foreground color from an attribute set.
     *
     * @param attr the attribute set
     * @return the color
     */
    public Color getForeground(AttributeSet attr) {
  StyleContext styles = (StyleContext) getAttributeContext();
  return styles.getForeground(attr);
    }

    /**
     * Gets the background color from an attribute set.
     *
     * @param attr the attribute set
     * @return the color
     */
    public Color getBackground(AttributeSet attr) {
  StyleContext styles = (StyleContext) getAttributeContext();
  return styles.getBackground(attr);
    }

    /**
     * Gets the font from an attribute set.
     *
     * @param attr the attribute set
     * @return the font
     */
    public Font getFont(AttributeSet attr) {
  StyleContext styles = (StyleContext) getAttributeContext();
  return styles.getFont(attr);
    }

    /**
     * Called when any of this document's styles have changed.
     * Subclasses may wish to be intelligent about what gets damaged.
     *
     * @param style The Style that has changed.
     */
    protected void styleChanged(Style style) {
        // Only propagate change updated if have content
        if (getLength() != 0) {
            // lazily create a ChangeUpdateRunnable
            if (updateRunnable == null) {
                updateRunnable = new ChangeUpdateRunnable();
            }
           
            // We may get a whole batch of these at once, so only
            // queue the runnable if it is not already pending
            synchronized(updateRunnable) {
                if (!updateRunnable.isPending) {
                    SwingUtilities.invokeLater(updateRunnable);
                    updateRunnable.isPending = true;
                }
            }
        }
    }

    /**
     * Adds a document listener for notification of any changes.
     *
     * @param listener the listener
     * @see Document#addDocumentListener
     */
    public void addDocumentListener(DocumentListener listener) {
  synchronized(listeningStyles) {
      int oldDLCount = listenerList.getListenerCount
                              (DocumentListener.class);
      super.addDocumentListener(listener);
      if (oldDLCount == 0) {
    if (styleContextChangeListener == null) {
        styleContextChangeListener =
                    createStyleContextChangeListener();
    }
    if (styleContextChangeListener != null) {
        StyleContext styles = (StyleContext)getAttributeContext();
                    List<ChangeListener> staleListeners =
                        AbstractChangeHandler.getStaleListeners(styleContextChangeListener);
                    for (ChangeListener l: staleListeners) {
                        styles.removeChangeListener(l);
                    }
                    styles.addChangeListener(styleContextChangeListener);
    }
    updateStylesListeningTo();
      }
  }
    }

    /**
     * Removes a document listener.
     *
     * @param listener the listener
     * @see Document#removeDocumentListener
     */
    public void removeDocumentListener(DocumentListener listener) {
  synchronized(listeningStyles) {
      super.removeDocumentListener(listener);
      if (listenerList.getListenerCount(DocumentListener.class) == 0) {
    for (int counter = listeningStyles.size() - 1; counter >= 0;
         counter--) {
        ((Style)listeningStyles.elementAt(counter)).
                  removeChangeListener(styleChangeListener);
    }
    listeningStyles.removeAllElements();
    if (styleContextChangeListener != null) {
        StyleContext styles = (StyleContext)getAttributeContext();
        styles.removeChangeListener(styleContextChangeListener);
    }
      }
  }
    }

    /**
     * Returns a new instance of StyleChangeHandler.
     */
    ChangeListener createStyleChangeListener() {
        return new StyleChangeHandler(this);
    }

    /**
     * Returns a new instance of StyleContextChangeHandler.
     */
    ChangeListener createStyleContextChangeListener() {
        return new StyleContextChangeHandler(this);
    }

    /**
     * Adds a ChangeListener to new styles, and removes ChangeListener from
     * old styles.
     */
    void updateStylesListeningTo() {
  synchronized(listeningStyles) {
      StyleContext styles = (StyleContext)getAttributeContext();
      if (styleChangeListener == null) {
    styleChangeListener = createStyleChangeListener();
      }
      if (styleChangeListener != null && styles != null) {
    Enumeration styleNames = styles.getStyleNames();
    Vector v = (Vector)listeningStyles.clone();
    listeningStyles.removeAllElements();
                List<ChangeListener> staleListeners =
                    AbstractChangeHandler.getStaleListeners(styleChangeListener);
    while (styleNames.hasMoreElements()) {
        String name = (String)styleNames.nextElement();
        Style aStyle = styles.getStyle(name);
        int index = v.indexOf(aStyle);
        listeningStyles.addElement(aStyle);
        if (index == -1) {
                        for (ChangeListener l: staleListeners) {
                            aStyle.removeChangeListener(l);
                        }
      aStyle.addChangeListener(styleChangeListener);
        }
        else {
      v.removeElementAt(index);
        }
    }
    for (int counter = v.size() - 1; counter >= 0; counter--) {
        Style aStyle = (Style)v.elementAt(counter);
        aStyle.removeChangeListener(styleChangeListener);
    }
    if (listeningStyles.size() == 0) {
        styleChangeListener = null;
    }
      }
  }
    }

    private void readObject(ObjectInputStream s)
            throws ClassNotFoundException, IOException {
  listeningStyles = new Vector();
  s.defaultReadObject();
  // Reinstall style listeners.
  if (styleContextChangeListener == null &&
      listenerList.getListenerCount(DocumentListener.class) > 0) {
      styleContextChangeListener = createStyleContextChangeListener();
      if (styleContextChangeListener != null) {
    StyleContext styles = (StyleContext)getAttributeContext();
    styles.addChangeListener(styleContextChangeListener);
      }
      updateStylesListeningTo();
  }
    }

    // --- member variables -----------------------------------------------------------

    /**
     * The default size of the initial content buffer.
     */
    public static final int BUFFER_SIZE_DEFAULT = 4096;

    protected ElementBuffer buffer;

    /** Styles listening to. */
    private transient Vector listeningStyles;

    /** Listens to Styles. */
    private transient ChangeListener styleChangeListener;

    /** Listens to Styles. */
    private transient ChangeListener styleContextChangeListener;
   
    /** Run to create a change event for the document */
    private transient ChangeUpdateRunnable updateRunnable;

    /**
     * Default root element for a document... maps out the
     * paragraphs/lines contained.
     * <p>
     * <strong>Warning:</strong>
     * Serialized objects of this class will not be compatible with
     * future Swing releases. The current serialization support is
     * appropriate for short term storage or RMI between applications running
     * the same version of Swing.  As of 1.4, support for long term storage
     * of all JavaBeans<sup><font size="-2">TM</font></sup>
     * has been added to the <code>java.beans</code> package.
     * Please see {@link java.beans.XMLEncoder}.
     */
    protected class SectionElement extends BranchElement {

        /**
         * Creates a new SectionElement.
         */
  public SectionElement() {
      super(null, null);
  }

        /**
         * Gets the name of the element.
         *
         * @return the name
         */
        public String getName() {
      return SectionElementName;
  }
    }

    /**
     * Specification for building elements.
     * <p>
     * <strong>Warning:</strong>
     * Serialized objects of this class will not be compatible with
     * future Swing releases. The current serialization support is
     * appropriate for short term storage or RMI between applications running
     * the same version of Swing.  As of 1.4, support for long term storage
     * of all JavaBeans<sup><font size="-2">TM</font></sup>
     * has been added to the <code>java.beans</code> package.
     * Please see {@link java.beans.XMLEncoder}.
     */
    public static class ElementSpec {

  /**
   * A possible value for getType.  This specifies
   * that this record type is a start tag and
   * represents markup that specifies the start
   * of an element.
   */
  public static final short StartTagType = 1;
 
  /**
   * A possible value for getType.  This specifies
   * that this record type is a end tag and
   * represents markup that specifies the end
   * of an element.
   */
  public static final short EndTagType = 2;

  /**
   * A possible value for getType.  This specifies
   * that this record type represents content.
   */
  public static final short ContentType = 3;
 
  /**
   * A possible value for getDirection.  This specifies
   * that the data associated with this record should
   * be joined to what precedes it.
   */
  public static final short JoinPreviousDirection = 4;
 
  /**
   * A possible value for getDirection.  This specifies
   * that the data associated with this record should
   * be joined to what follows it.
   */
  public static final short JoinNextDirection = 5;
 
  /**
   * A possible value for getDirection.  This specifies
   * that the data associated with this record should
   * be used to originate a new element.  This would be
   * the normal value.
   */
  public static final short OriginateDirection = 6;

  /**
   * A possible value for getDirection.  This specifies
   * that the data associated with this record should
   * be joined to the fractured element.
   */
  public static final short JoinFractureDirection = 7;

 
  /**
   * Constructor useful for markup when the markup will not
   * be stored in the document.
         *
         * @param a the attributes for the element
         * @param type the type of the element (StartTagType, EndTagType,
         *  ContentType)
   */
  public ElementSpec(AttributeSet a, short type) {
      this(a, type, null, 0, 0);
  }

  /**
   * Constructor for parsing inside the document when
   * the data has already been added, but len information
   * is needed.
         *
         * @param a the attributes for the element
         * @param type the type of the element (StartTagType, EndTagType,
         *  ContentType)
         * @param len the length >= 0
   */
  public ElementSpec(AttributeSet a, short type, int len) {
      this(a, type, null, 0, len);
  }

  /**
   * Constructor for creating a spec externally for batch
   * input of content and markup into the document.
         *
         * @param a the attributes for the element
         * @param type the type of the element (StartTagType, EndTagType,
         *  ContentType)
         * @param txt the text for the element
         * @param offs the offset into the text >= 0
         * @param len the length of the text >= 0
   */
        public ElementSpec(AttributeSet a, short type, char[] txt,
          int offs, int len) {
      attr = a;
      this.type = type;
      this.data = txt;
      this.offs = offs;
      this.len = len;
      this.direction = OriginateDirection;
  }

        /**
         * Sets the element type.
         *
         * @param type the type of the element (StartTagType, EndTagType,
         *  ContentType)
         */
  public void setType(short type) {
      this.type = type;
  }

        /**
         * Gets the element type.
         *
         * @return  the type of the element (StartTagType, EndTagType,
         *  ContentType)
         */
  public short getType() {
      return type;
  }

        /**
         * Sets the direction.
         *
         * @param direction the direction (JoinPreviousDirection,
         *   JoinNextDirection)
         */
  public void setDirection(short direction) {
      this.direction = direction;
  }

        /**
         * Gets the direction.
         *
         * @return the direction (JoinPreviousDirection, JoinNextDirection)
         */
  public short getDirection() {
      return direction;
  }

        /**
         * Gets the element attributes.
         *
         * @return the attribute set
         */
  public AttributeSet getAttributes() {
      return attr;
  }

        /**
         * Gets the array of characters.
         *
         * @return the array
         */
  public char[] getArray() {
      return data;
  }


        /**
         * Gets the starting offset.
         *
         * @return the offset >= 0
         */
  public int getOffset() {
      return offs;
  }

        /**
         * Gets the length.
         *
         * @return the length >= 0
         */
  public int getLength() {
      return len;
  }

        /**
         * Converts the element to a string.
         *
         * @return the string
         */
        public String toString() {
      String tlbl = "??";
      String plbl = "??";
      switch(type) {
      case StartTagType:
    tlbl = "StartTag";
    break;
      case ContentType:
    tlbl = "Content";
    break;
      case EndTagType:
    tlbl = "EndTag";
    break;
      }
      switch(direction) {
      case JoinPreviousDirection:
    plbl = "JoinPrevious";
    break;
      case JoinNextDirection:
    plbl = "JoinNext";
    break;
      case OriginateDirection:
    plbl = "Originate";
    break;
      case JoinFractureDirection:
    plbl = "Fracture";
    break;
      }
      return tlbl + ":" + plbl + ":" + getLength();
  }
   
  private AttributeSet attr;
  private int len;
  private short type;
  private short direction;

  private int offs;
  private char[] data;
    }

    /**
     * Class to manage changes to the element
     * hierarchy.
     * <p>
     * <strong>Warning:</strong>
     * Serialized objects of this class will not be compatible with
     * future Swing releases. The current serialization support is
     * appropriate for short term storage or RMI between applications running
     * the same version of Swing.  As of 1.4, support for long term storage
     * of all JavaBeans<sup><font size="-2">TM</font></sup>
     * has been added to the <code>java.beans</code> package.
     * Please see {@link java.beans.XMLEncoder}.
     */
    public class ElementBuffer implements Serializable {

        /**
         * Creates a new ElementBuffer.
         *
         * @param root the root element
   * @since 1.4
         */
  public ElementBuffer(Element root) {
      this.root = root;
      changes = new Vector();
      path = new Stack();
  }

        /**
         * Gets the root element.
         *
         * @return the root element
         */
        public Element getRootElement() {
      return root;
  }

        /**
         * Inserts new content.
         *
         * @param offset the starting offset >= 0
         * @param length the length >= 0
         * @param data the data to insert
         * @param de the event capturing this edit
         */
  public void insert(int offset, int length, ElementSpec[] data,
         DefaultDocumentEvent de) {
      if (length == 0) {
    // Nothing was inserted, no structure change.
    return;
      }
      insertOp = true;
      beginEdits(offset, length);
      insertUpdate(data);
      endEdits(de);

      insertOp = false;
  }

  void create(int length, ElementSpec[] data, DefaultDocumentEvent de) {
      insertOp = true;
      beginEdits(offset, length);

      // PENDING(prinz) this needs to be fixed to create a new
      // root element as well, but requires changes to the
      // DocumentEvent to inform the views that there is a new
      // root element.

      // Recreate the ending fake element to have the correct offsets.
      Element elem = root;
      int index = elem.getElementIndex(0);
      while (! elem.isLeaf()) {
    Element child = elem.getElement(index);
    push(elem, index);
    elem = child;
    index = elem.getElementIndex(0);
      }
      ElemChanges ec = (ElemChanges) path.peek();
      Element child = ec.parent.getElement(ec.index);
      ec.added.addElement(createLeafElement(ec.parent,
        child.getAttributes(), getLength(),
        child.getEndOffset()));
      ec.removed.addElement(child);
      while (path.size() > 1) {
    pop();
      }

      int n = data.length;

      // Reset the root elements attributes.
      AttributeSet newAttrs = null;
      if (n > 0 && data[0].getType() == ElementSpec.StartTagType) {
    newAttrs = data[0].getAttributes();
      }
      if (newAttrs == null) {
    newAttrs = SimpleAttributeSet.EMPTY;
      }
      MutableAttributeSet attr = (MutableAttributeSet)root.
                           getAttributes();
      de.addEdit(new AttributeUndoableEdit(root, newAttrs, true));
      attr.removeAttributes(attr);
      attr.addAttributes(newAttrs);

      // fold in the specified subtree
      for (int i = 1; i < n; i++) {
    insertElement(data[i]);
      }

      // pop the remaining path
      while (path.size() != 0) {
    pop();
      }

      endEdits(de);
      insertOp = false;
  }

        /**
         * Removes content.
         *
         * @param offset the starting offset >= 0
         * @param length the length >= 0
         * @param de the event capturing this edit
         */
  public void remove(int offset, int length, DefaultDocumentEvent de) {
      beginEdits(offset, length);
      removeUpdate();
      endEdits(de);
  }

        /**
         * Changes content.
         *
         * @param offset the starting offset >= 0
         * @param length the length >= 0
         * @param de the event capturing this edit
         */
        public void change(int offset, int length, DefaultDocumentEvent de) {
      beginEdits(offset, length);
      changeUpdate();
      endEdits(de);
  }

        /**
         * Inserts an update into the document.
         *
         * @param data the elements to insert
         */
  protected void insertUpdate(ElementSpec[] data) {
      // push the path
      Element elem = root;
      int index = elem.getElementIndex(offset);
      while (! elem.isLeaf()) {
    Element child = elem.getElement(index);
    push(elem, (child.isLeaf() ? index : index+1));
    elem = child;
    index = elem.getElementIndex(offset);
      }

      // Build a copy of the original path.
      insertPath = new ElemChanges[path.size()];
      path.copyInto(insertPath);

      // Haven't created the fracture yet.
      createdFracture = false;

      // Insert the first content.
      int i;

      recreateLeafs = false;
      if(data[0].getType() == ElementSpec.ContentType) {
    insertFirstContent(data);
    pos += data[0].getLength();
    i = 1;
      }
      else {
    fractureDeepestLeaf(data);
    i = 0;
      }

      // fold in the specified subtree
      int n = data.length;
      for (; i < n; i++) {
    insertElement(data[i]);
      }

      // Fracture, if we haven't yet.
      if(!createdFracture)
    fracture(-1);

      // pop the remaining path
      while (path.size() != 0) {
    pop();
      }

      // Offset the last index if necessary.
      if(offsetLastIndex && offsetLastIndexOnReplace) {
    insertPath[insertPath.length - 1].index++;
      }

      // Make sure an edit is going to be created for each of the
      // original path items that have a change.
      for(int counter = insertPath.length - 1; counter >= 0;
    counter--) {
    ElemChanges change = insertPath[counter];
    if(change.parent == fracturedParent)
        change.added.addElement(fracturedChild);
    if((change.added.size() > 0 ||
        change.removed.size() > 0) && !changes.contains(change)) {
        // PENDING(sky): Do I need to worry about order here?
        changes.addElement(change);
    }
      }

      // An insert at 0 with an initial end implies some elements
      // will have no children (the bottomost leaf would have length 0)
      // this will find what element need to be removed and remove it.
      if (offset == 0 && fracturedParent != null &&
    data[0].getType() == ElementSpec.EndTagType) {
    int counter = 0;
    while (counter < data.length &&
           data[counter].getType() == ElementSpec.EndTagType) {
        counter++;
    }
    ElemChanges change = insertPath[insertPath.length -
                 counter - 1];
    change.removed.insertElementAt(change.parent.getElement
                 (--change.index), 0);
      }
  }

  /**
   * Updates the element structure in response to a removal from the
   * associated sequence in the document.  Any elements consumed by the
   * span of the removal are removed. 
   */
  protected void removeUpdate() {
      removeElements(root, offset, offset + length);
  }

        /**
         * Updates the element structure in response to a change in the
         * document.
         */
        protected void changeUpdate() {
      boolean didEnd = split(offset, length);
      if (! didEnd) {
    // need to do the other end
    while (path.size() != 0) {
        pop();
    }
    split(offset + length, 0);
      }
      while (path.size() != 0) {
    pop();
      }
  }

  boolean split(int offs, int len) {
      boolean splitEnd = false;
      // push the path
      Element e = root;
      int index = e.getElementIndex(offs);
      while (! e.isLeaf()) {
    push(e, index);
    e = e.getElement(index);
    index = e.getElementIndex(offs);
      }

      ElemChanges ec = (ElemChanges) path.peek();
      Element child = ec.parent.getElement(ec.index);
      // make sure there is something to do... if the
      // offset is already at a boundary then there is
      // nothing to do.
      if (child.getStartOffset() < offs && offs < child.getEndOffset()) {
    // we need to split, now see if the other end is within
    // the same parent.
    int index0 = ec.index;
    int index1 = index0;
    if (((offs + len) < ec.parent.getEndOffset()) && (len != 0)) {
        // it's a range split in the same parent
        index1 = ec.parent.getElementIndex(offs+len);
        if (index1 == index0) {
      // it's a three-way split
      ec.removed.addElement(child);
      e = createLeafElement(ec.parent, child.getAttributes(),
                child.getStartOffset(), offs);
      ec.added.addElement(e);
      e = createLeafElement(ec.parent, child.getAttributes(),
            offs, offs + len);
      ec.added.addElement(e);
      e = createLeafElement(ec.parent, child.getAttributes(),
                offs + len, child.getEndOffset());
      ec.added.addElement(e);
      return true;
        } else {
      child = ec.parent.getElement(index1);
      if ((offs + len) == child.getStartOffset()) {
          // end is already on a boundary
          index1 = index0;
      }
        }
        splitEnd = true;
    }

    // split the first location
    pos = offs;
    child = ec.parent.getElement(index0);
    ec.removed.addElement(child);
    e = createLeafElement(ec.parent, child.getAttributes(),
              child.getStartOffset(), pos);
    ec.added.addElement(e);
    e = createLeafElement(ec.parent, child.getAttributes(),
              pos, child.getEndOffset());
    ec.added.addElement(e);

    // pick up things in the middle
    for (int i = index0 + 1; i < index1; i++) {
        child = ec.parent.getElement(i);
        ec.removed.addElement(child);
        ec.added.addElement(child);
    }

    if (index1 != index0) {
        child = ec.parent.getElement(index1);
        pos = offs + len;
        ec.removed.addElement(child);
        e = createLeafElement(ec.parent, child.getAttributes(),
            child.getStartOffset(), pos);
        ec.added.addElement(e);
        e = createLeafElement(ec.parent, child.getAttributes(),
            pos, child.getEndOffset());
        ec.added.addElement(e);
    }
      }
      return splitEnd;
  }

  /**
   * Creates the UndoableEdit record for the edits made
   * in the buffer.
   */
  void endEdits(DefaultDocumentEvent de) {
      int n = changes.size();
      for (int i = 0; i < n; i++) {
    ElemChanges ec = (ElemChanges) changes.elementAt(i);
    Element[] removed = new Element[ec.removed.size()];
    ec.removed.copyInto(removed);
    Element[] added = new Element[ec.added.size()];
    ec.added.copyInto(added);
    int index = ec.index;
    ((BranchElement) ec.parent).replace(index, removed.length, added);
    ElementEdit ee = new ElementEdit((BranchElement) ec.parent,
             index, removed, added);
    de.addEdit(ee);
      }
     
      changes.removeAllElements();
      path.removeAllElements();

      /*
      for (int i = 0; i < n; i++) {
    ElemChanges ec = (ElemChanges) changes.elementAt(i);
    System.err.print("edited: " + ec.parent + " at: " + ec.index +
        " removed " + ec.removed.size());
    if (ec.removed.size() > 0) {
        int r0 = ((Element) ec.removed.firstElement()).getStartOffset();
        int r1 = ((Element) ec.removed.lastElement()).getEndOffset();
        System.err.print("[" + r0 + "," + r1 + "]");
    }
    System.err.print(" added " + ec.added.size());
    if (ec.added.size() > 0) {
        int p0 = ((Element) ec.added.firstElement()).getStartOffset();
        int p1 = ((Element) ec.added.lastElement()).getEndOffset();
        System.err.print("[" + p0 + "," + p1 + "]");
    }
    System.err.println("");
      }
      */
  }

  /**
   * Initialize the buffer
   */
  void beginEdits(int offset, int length) {
      this.offset = offset;
      this.length = length;
      this.endOffset = offset + length;
      pos = offset;
      if (changes == null) {
    changes = new Vector();
      } else {
    changes.removeAllElements();
      }
      if (path == null) {
    path = new Stack();
      } else {
    path.removeAllElements();
      }
      fracturedParent = null;
      fracturedChild = null;
      offsetLastIndex = offsetLastIndexOnReplace = false;
  }

  /**
   * Pushes a new element onto the stack that represents
   * the current path.
   * @param record Whether or not the push should be
   *  recorded as an element change or not.
   * @param isFracture true if pushing on an element that was created
   * as the result of a fracture.
   */
  void push(Element e, int index, boolean isFracture) {
      ElemChanges ec = new ElemChanges(e, index, isFracture);
      path.push(ec);
  }

  void push(Element e, int index) {
      push(e, index, false);
  }

  void pop() {
      ElemChanges ec = (ElemChanges) path.peek();
      path.pop();
      if ((ec.added.size() > 0) || (ec.removed.size() > 0)) {
    changes.addElement(ec);
      } else if (! path.isEmpty()) {
    Element e = ec.parent;
    if(e.getElementCount() == 0) {
        // if we pushed a branch element that didn't get
        // used, make sure its not marked as having been added.
        ec = (ElemChanges) path.peek();
        ec.added.removeElement(e);
    }
      }
  }

  /**
   * move the current offset forward by n.
   */
  void advance(int n) {
      pos += n;
  }

  void insertElement(ElementSpec es) {
      ElemChanges ec = (ElemChanges) path.peek();
      switch(es.getType()) {
      case ElementSpec.StartTagType:
    switch(es.getDirection()) {
    case ElementSpec.JoinNextDirection:
        // Don't create a new element, use the existing one
        // at the specified location.
        Element parent = ec.parent.getElement(ec.index);

        if(parent.isLeaf()) {
      // This happens if inserting into a leaf, followed
      // by a join next where next sibling is not a leaf.
      if((ec.index + 1) < ec.parent.getElementCount())
          parent = ec.parent.getElement(ec.index + 1);
      else
          throw new StateInvariantError("Join next to leaf");
        }
        // Not really a fracture, but need to treat it like
        // one so that content join next will work correctly.
        // We can do this because there will never be a join
        // next followed by a join fracture.
        push(parent, 0, true);
        break;
    case ElementSpec.JoinFractureDirection:
        if(!createdFracture) {
      // Should always be something on the stack!
      fracture(path.size() - 1);
        }
        // If parent isn't a fracture, fracture will be
        // fracturedChild.
        if(!ec.isFracture) {
      push(fracturedChild, 0, true);
        }
        else
      // Parent is a fracture, use 1st element.
      push(ec.parent.getElement(0), 0, true);
        break;
    default:
        Element belem = createBranchElement(ec.parent,
              es.getAttributes());
        ec.added.addElement(belem);
        push(belem, 0);
        break;
    }
    break;
      case ElementSpec.EndTagType:
    pop();
    break;
      case ElementSpec.ContentType:
        int len = es.getLength();
    if (es.getDirection() != ElementSpec.JoinNextDirection) {
        Element leaf = createLeafElement(ec.parent, es.getAttributes(),
                 pos, pos + len);
        ec.added.addElement(leaf);
    }
    else {
        // JoinNext on tail is only applicable if last element
        // and attributes come from that of first element.
        // With a little extra testing it would be possible
        // to NOT due this again, as more than likely fracture()
        // created this element.
        if(!ec.isFracture) {
      Element first = null;
      if(insertPath != null) {
          for(int counter = insertPath.length - 1;
        counter >= 0; counter--) {
        if(insertPath[counter] == ec) {
            if(counter != (insertPath.length - 1))
          first = ec.parent.getElement(ec.index);
            break;
        }
          }
      }
      if(first == null)
          first = ec.parent.getElement(ec.index + 1);
      Element leaf = createLeafElement(ec.parent, first.
               getAttributes(), pos, first.getEndOffset());
      ec.added.addElement(leaf);
      ec.removed.addElement(first);
        }
        else {
      // Parent was fractured element.
      Element first = ec.parent.getElement(0);
      Element leaf = createLeafElement(ec.parent, first.
               getAttributes(), pos, first.getEndOffset());
      ec.added.addElement(leaf);
      ec.removed.addElement(first);
        }
    }
    pos += len;
    break;
      }
  }
     
  /**
   * Remove the elements from <code>elem</code> in range
   * <code>rmOffs0</code>, <code>rmOffs1</code>. This uses
   * <code>canJoin</code> and <code>join</code> to handle joining
   * the endpoints of the insertion.
   *
   * @return true if elem will no longer have any elements.
   */
  boolean removeElements(Element elem, int rmOffs0, int rmOffs1) {
      if (! elem.isLeaf()) {
    // update path for changes
    int index0 = elem.getElementIndex(rmOffs0);
    int index1 = elem.getElementIndex(rmOffs1);
    push(elem, index0);
    ElemChanges ec = (ElemChanges)path.peek();

    // if the range is contained by one element,
    // we just forward the request
    if (index0 == index1) {
        Element child0 = elem.getElement(index0);
        if(rmOffs0 <= child0.getStartOffset() &&
           rmOffs1 >= child0.getEndOffset()) {
      // Element totally removed.
      ec.removed.addElement(child0);
        }
        else if(removeElements(child0, rmOffs0, rmOffs1)) {
      ec.removed.addElement(child0);
        }
    } else {
        // the removal range spans elements.  If we can join
        // the two endpoints, do it.  Otherwise we remove the
        // interior and forward to the endpoints.
        Element child0 = elem.getElement(index0);
        Element child1 = elem.getElement(index1);
        boolean containsOffs1 = (rmOffs1 < elem.getEndOffset());
        if (containsOffs1 && canJoin(child0, child1)) {
      // remove and join
      for (int i = index0; i <= index1; i++) {
          ec.removed.addElement(elem.getElement(i));
      }
      Element e = join(elem, child0, child1, rmOffs0, rmOffs1);
      ec.added.addElement(e);
        } else {
      // remove interior and forward
      int rmIndex0 = index0 + 1;
      int rmIndex1 = index1 - 1;
      if (child0.getStartOffset() == rmOffs0 ||
          (index0 == 0 &&
           child0.getStartOffset() > rmOffs0 &&
           child0.getEndOffset() <= rmOffs1)) {
          // start element completely consumed
          child0 = null;
          rmIndex0 = index0;
      }
      if (!containsOffs1) {
          child1 = null;
          rmIndex1++;
      }
      else if (child1.getStartOffset() == rmOffs1) {
          // end element not touched
          child1 = null;
      }
      if (rmIndex0 <= rmIndex1) {
          ec.index = rmIndex0;
      }
      for (int i = rmIndex0; i <= rmIndex1; i++) {
          ec.removed.addElement(elem.getElement(i));
      }
      if (child0 != null) {
          if(removeElements(child0, rmOffs0, rmOffs1)) {
        ec.removed.insertElementAt(child0, 0);
        ec.index = index0;
          }
      }
      if (child1 != null) {
          if(removeElements(child1, rmOffs0, rmOffs1)) {
        ec.removed.addElement(child1);
          }
      }
        }
    }

    // publish changes
    pop();

    // Return true if we no longer have any children.
    if(elem.getElementCount() == (ec.removed.size() -
                ec.added.size())) {
        return true;
    }
      }
      return false;
  }

  /**
   * Can the two given elements be coelesced together
   * into one element?
   */
  boolean canJoin(Element e0, Element e1) {
      if ((e0 == null) || (e1 == null)) {
    return false;
      }
      // Don't join a leaf to a branch.
            boolean leaf0 = e0.isLeaf();
            boolean leaf1 = e1.isLeaf();
      if(leaf0 != leaf1) {
    return false;
            }
            if (leaf0) {
                // Only join leaves if the attributes match, otherwise
                // style information will be lost.
                return e0.getAttributes().isEqual(e1.getAttributes());
            }
            // Only join non-leafs if the names are equal. This may result
            // in loss of style information, but this is typically acceptable
            // for non-leafs.
            String name0 = e0.getName();
            String name1 = e1.getName();
            if (name0 != null) {
                return name0.equals(name1);
            }
            if (name1 != null) {
                return name1.equals(name0);
            }
            // Both names null, treat as equal.
            return true;
  }

  /**
   * Joins the two elements carving out a hole for the
   * given removed range.
   */
  Element join(Element p, Element left, Element right, int rmOffs0, int rmOffs1) {
      if (left.isLeaf() && right.isLeaf()) {
    return createLeafElement(p, left.getAttributes(), left.getStartOffset(),
           right.getEndOffset());
      } else if ((!left.isLeaf()) && (!right.isLeaf())) {
    // join two branch elements.  This copies the children before
    // the removal range on the left element, and after the removal
    // range on the right element.  The two elements on the edge
    // are joined if possible and needed.
    Element to = createBranchElement(p, left.getAttributes());
    int ljIndex = left.getElementIndex(rmOffs0);
    int rjIndex = right.getElementIndex(rmOffs1);
    Element lj = left.getElement(ljIndex);
    if (lj.getStartOffset() >= rmOffs0) {
        lj = null;
    }
    Element rj = right.getElement(rjIndex);
    if (rj.getStartOffset() == rmOffs1) {
        rj = null;
    }
    Vector children = new Vector();

    // transfer the left
    for (int i = 0; i < ljIndex; i++) {
        children.addElement(clone(to, left.getElement(i)));
    }

    // transfer the join/middle
    if (canJoin(lj, rj)) {
        Element e = join(to, lj, rj, rmOffs0, rmOffs1);
        children.addElement(e);
    } else {
        if (lj != null) {
      children.addElement(cloneAsNecessary(to, lj, rmOffs0, rmOffs1));
        }
        if (rj != null) {
      children.addElement(cloneAsNecessary(to, rj, rmOffs0, rmOffs1));
        }
    }

    // transfer the right
    int n = right.getElementCount();
    for (int i = (rj == null) ? rjIndex : rjIndex + 1; i < n; i++) {
        children.addElement(clone(to, right.getElement(i)));
    }

    // install the children
    Element[] c = new Element[children.size()];
    children.copyInto(c);
    ((BranchElement)to).replace(0, 0, c);
    return to;
      } else {
    throw new StateInvariantError(
        "No support to join leaf element with non-leaf element");
      }
  }

  /**
   * Creates a copy of this element, with a different
   * parent.
         *
         * @param parent the parent element
         * @param clonee the element to be cloned
         * @return the copy
   */
        public Element clone(Element parent, Element clonee) {
      if (clonee.isLeaf()) {
    return createLeafElement(parent, clonee.getAttributes(),
           clonee.getStartOffset(),
           clonee.getEndOffset());
      }
      Element e = createBranchElement(parent, clonee.getAttributes());
      int n = clonee.getElementCount();
      Element[] children = new Element[n];
      for (int i = 0; i < n; i++) {
    children[i] = clone(e, clonee.getElement(i));
      }
      ((BranchElement)e).replace(0, 0, children);
      return e;
  }

        /**
         * Creates a copy of this element, with a different
         * parent. Children of this element included in the
         * removal range will be discarded.
         */
        Element cloneAsNecessary(Element parent, Element clonee, int rmOffs0, int rmOffs1) {
            if (clonee.isLeaf()) {
                return createLeafElement(parent, clonee.getAttributes(),
                                         clonee.getStartOffset(),
                                         clonee.getEndOffset());
            }
            Element e = createBranchElement(parent, clonee.getAttributes());
            int n = clonee.getElementCount();
            ArrayList childrenList = new ArrayList(n);
            for (int i = 0; i < n; i++) {
                Element elem = clonee.getElement(i);
                if (elem.getStartOffset() < rmOffs0 || elem.getEndOffset() > rmOffs1) {
                    childrenList.add(cloneAsNecessary(e, elem, rmOffs0, rmOffs1));
                }
            }
            Element[] children = new Element[childrenList.size()];
            children = (Element[])childrenList.toArray(children);
            ((BranchElement)e).replace(0, 0, children);
            return e;
        }

  /**
   * Determines if a fracture needs to be performed. A fracture
   * can be thought of as moving the right part of a tree to a
   * new location, where the right part is determined by what has
   * been inserted. <code>depth</code> is used to indicate a
   * JoinToFracture is needed to an element at a depth
   * of <code>depth</code>. Where the root is 0, 1 is the children
   * of the root...
   * <p>This will invoke <code>fractureFrom</code> if it is determined
   * a fracture needs to happen.
   */
  void fracture(int depth) {
      int cLength = insertPath.length;
      int lastIndex = -1;
      boolean needRecreate = recreateLeafs;
      ElemChanges lastChange = insertPath[cLength - 1];
      // Use childAltered to determine when a child has been altered,
      // that is the point of insertion is less than the element count.
      boolean childAltered = ((lastChange.index + 1) <
            lastChange.parent.getElementCount());
      int deepestAlteredIndex = (needRecreate) ? cLength : -1;
      int lastAlteredIndex = cLength - 1;

      createdFracture = true;
      // Determine where to start recreating from.
      // Start at - 2, as first one is indicated by recreateLeafs and
      // childAltered.
      for(int counter = cLength - 2; counter >= 0; counter--) {
    ElemChanges change = insertPath[counter];
    if(change.added.size() > 0 || counter == depth) {
        lastIndex = counter;
        if(!needRecreate && childAltered) {
      needRecreate = true;
      if(deepestAlteredIndex == -1)
          deepestAlteredIndex = lastAlteredIndex + 1;
        }
    }
    if(!childAltered && change.index <
       change.parent.getElementCount()) {
        childAltered = true;
        lastAlteredIndex = counter;
    }
      }
      if(needRecreate) {
    // Recreate all children to right of parent starting
    // at lastIndex.
    if(lastIndex == -1)
        lastIndex = cLength - 1;
    fractureFrom(insertPath, lastIndex, deepestAlteredIndex);
      }
  }

  /**
   * Recreates the elements to the right of the insertion point.
   * This starts at <code>startIndex</code> in <code>changed</code>,
   * and calls duplicate to duplicate existing elements.
   * This will also duplicate the elements along the insertion
   * point, until a depth of <code>endFractureIndex</code> is
   * reached, at which point only the elements to the right of
   * the insertion point are duplicated.
   */
  void fractureFrom(ElemChanges[] changed, int startIndex,
        int endFractureIndex) {
      // Recreate the element representing the inserted index.
      ElemChanges change = changed[startIndex];
      Element child;
      Element newChild;
      int changeLength = changed.length;

      if((startIndex + 1) == changeLength)
    child = change.parent.getElement(change.index);
      else
    child = change.parent.getElement(change.index - 1);
      if(child.isLeaf()) {
    newChild = createLeafElement(change.parent,
             child.getAttributes(), Math.max(endOffset,
             child.getStartOffset()), child.getEndOffset());
      }
      else {
    newChild = createBranchElement(change.parent,
                 child.getAttributes());
      }
      fracturedParent = change.parent;
      fracturedChild = newChild;

      // Recreate all the elements to the right of the
      // insertion point.
      Element parent = newChild;

      while(++startIndex < endFractureIndex) {
    boolean isEnd = ((startIndex + 1) == endFractureIndex);
    boolean isEndLeaf = ((startIndex + 1) == changeLength);

    // Create the newChild, a duplicate of the elment at
    // index. This isn't done if isEnd and offsetLastIndex are true
    // indicating a join previous was done.
    change = changed[startIndex];

    // Determine the child to duplicate, won't have to duplicate
    // if at end of fracture, or offseting index.
    if(isEnd) {
        if(offsetLastIndex || !isEndLeaf)
      child = null;
        else
      child = change.parent.getElement(change.index);
    }
    else {
        child = change.parent.getElement(change.index - 1);
    }
    // Duplicate it.
    if(child != null) {
        if(child.isLeaf()) {
      newChild = createLeafElement(parent,
             child.getAttributes(), Math.max(endOffset,
             child.getStartOffset()), child.getEndOffset());
        }
        else {
      newChild = createBranchElement(parent,
               child.getAttributes());
        }
    }
    else
        newChild = null;

    // Recreate the remaining children (there may be none).
    int kidsToMove = change.parent.getElementCount() -
                     change.index;
    Element[] kids;
    int moveStartIndex;
    int kidStartIndex = 1;

    if(newChild == null) {
        // Last part of fracture.
        if(isEndLeaf) {
      kidsToMove--;
      moveStartIndex = change.index + 1;
        }
        else {
      moveStartIndex = change.index;
        }
        kidStartIndex = 0;
        kids = new Element[kidsToMove];
    }
    else {
        if(!isEnd) {
      // Branch.
      kidsToMove++;
      moveStartIndex = change.index;
        }
        else {
      // Last leaf, need to recreate part of it.
      moveStartIndex = change.index + 1;
        }
        kids = new Element[kidsToMove];
        kids[0] = newChild;
    }

    for(int counter = kidStartIndex; counter < kidsToMove;
        counter++) {
        Element toMove =change.parent.getElement(moveStartIndex++);
        kids[counter] = recreateFracturedElement(parent, toMove);
        change.removed.addElement(toMove);
    }
    ((BranchElement)parent).replace(0, 0, kids);
    parent = newChild;
      }
  }

  /**
   * Recreates <code>toDuplicate</code>. This is called when an
   * element needs to be created as the result of an insertion. This
   * will recurse and create all the children. This is similiar to
   * <code>clone</code>, but deteremines the offsets differently.
   */
  Element recreateFracturedElement(Element parent, Element toDuplicate) {
      if(toDuplicate.isLeaf()) {
    return createLeafElement(parent, toDuplicate.getAttributes(),
           Math.max(toDuplicate.getStartOffset(),
              endOffset),
           toDuplicate.getEndOffset());
      }
      // Not a leaf
      Element newParent = createBranchElement(parent, toDuplicate.
                getAttributes());
      int childCount = toDuplicate.getElementCount();
      Element[] newKids = new Element[childCount];
      for(int counter = 0; counter < childCount; counter++) {
    newKids[counter] = recreateFracturedElement(newParent,
               toDuplicate.getElement(counter));
      }
      ((BranchElement)newParent).replace(0, 0, newKids);
      return newParent;
  }

  /**
   * Splits the bottommost leaf in <code>path</code>.
   * This is called from insert when the first element is NOT content.
   */
  void fractureDeepestLeaf(ElementSpec[] specs) {
      // Split the bottommost leaf. It will be recreated elsewhere.
      ElemChanges ec = (ElemChanges) path.peek();
      Element child = ec.parent.getElement(ec.index);
      // Inserts at offset 0 do not need to recreate child (it would
      // have a length of 0!).
      if (offset != 0) {
    Element newChild = createLeafElement(ec.parent,
             child.getAttributes(),
             child.getStartOffset(),
             offset);

    ec.added.addElement(newChild);
      }
      ec.removed.addElement(child);
      if(child.getEndOffset() != endOffset)
    recreateLeafs = true;
      else
    offsetLastIndex = true;
  }

  /**
   * Inserts the first content. This needs to be separate to handle
   * joining.
   */
  void insertFirstContent(ElementSpec[] specs) {
      ElementSpec firstSpec = specs[0];
      ElemChanges ec = (ElemChanges) path.peek();
      Element child = ec.parent.getElement(ec.index);
      int firstEndOffset = offset + firstSpec.getLength();
      boolean isOnlyContent = (specs.length == 1);

      switch(firstSpec.getDirection()) {
      case ElementSpec.JoinPreviousDirection:
    if(child.getEndOffset() != firstEndOffset &&
        !isOnlyContent) {
        // Create the left split part containing new content.
        Element newE = createLeafElement(ec.parent,
          child.getAttributes(), child.getStartOffset(),
          firstEndOffset);
        ec.added.addElement(newE);
        ec.removed.addElement(child);
        // Remainder will be created later.
        if(child.getEndOffset() != endOffset)
      recreateLeafs = true;
        else
      offsetLastIndex = true;
    }
    else {
        offsetLastIndex = true;
        offsetLastIndexOnReplace = true;
    }
    // else Inserted at end, and is total length.
    // Update index incase something added/removed.
    break;
      case ElementSpec.JoinNextDirection:
    if(offset != 0) {
        // Recreate the first element, its offset will have
        // changed.
        Element newE = createLeafElement(ec.parent,
          child.getAttributes(), child.getStartOffset(),
          offset);
        ec.added.addElement(newE);
        // Recreate the second, merge part. We do no checking
        // to see if JoinNextDirection is valid here!
        Element nextChild = ec.parent.getElement(ec.index + 1);
        if(isOnlyContent)
      newE = createLeafElement(ec.parent, nextChild.
          getAttributes(), offset, nextChild.getEndOffset());
        else
      newE = createLeafElement(ec.parent, nextChild.
          getAttributes(), offset, firstEndOffset);
        ec.added.addElement(newE);
        ec.removed.addElement(child);
        ec.removed.addElement(nextChild);
    }
    // else nothin to do.
    // PENDING: if !isOnlyContent could raise here!
    break;
      default:
    // Inserted into middle, need to recreate split left
    // new content, and split right.
    if(child.getStartOffset() != offset) {
        Element newE = createLeafElement(ec.parent,
          child.getAttributes(), child.getStartOffset(),
          offset);
        ec.added.addElement(newE);
    }
    ec.removed.addElement(child);
    // new content
    Element newE = createLeafElement(ec.parent,
             firstSpec.getAttributes(),
             offset, firstEndOffset);
    ec.added.addElement(newE);
    if(child.getEndOffset() != endOffset) {
        // Signals need to recreate right split later.
        recreateLeafs = true;
    }
    else {
        offsetLastIndex = true;
    }
    break;
      }
  }

  Element root;
  transient int pos;          // current position
  transient int offset;
  transient int length;
  transient int endOffset;
  transient Vector changes;  // Vector<ElemChanges>
  transient Stack path;      // Stack<ElemChanges>
  transient boolean insertOp;

  transient boolean recreateLeafs; // For insert.

  /** For insert, path to inserted elements. */
  transient ElemChanges[] insertPath;
  /** Only for insert, set to true when the fracture has been created. */
  transient boolean createdFracture;
  /** Parent that contains the fractured child. */
  transient Element fracturedParent;
  /** Fractured child. */
  transient Element fracturedChild;
  /** Used to indicate when fracturing that the last leaf should be
   * skipped. */
  transient boolean offsetLastIndex;
  /** Used to indicate that the parent of the deepest leaf should
   * offset the index by 1 when adding/removing elements in an
   * insert. */
  transient boolean offsetLastIndexOnReplace;

  /*
   * Internal record used to hold element change specifications
   */
  class ElemChanges {
     
      ElemChanges(Element parent, int index, boolean isFracture) {
    this.parent = parent;
    this.index = index;
    this.isFracture = isFracture;
    added = new Vector();
    removed = new Vector();
      }

            public String toString() {
    return "added: " + added + "\nremoved: " + removed + "\n";
      }
     
      Element parent;
      int index;
      Vector added;
      Vector removed;
      boolean isFracture;
  }   

    }

    /**
     * An UndoableEdit used to remember AttributeSet changes to an
     * Element.
     */
    public static class AttributeUndoableEdit extends AbstractUndoableEdit {
  public AttributeUndoableEdit(Element element, AttributeSet newAttributes,
            boolean isReplacing) {
      super();
      this.element = element;
      this.newAttributes = newAttributes;
      this.isReplacing = isReplacing;
      // If not replacing, it may be more efficient to only copy the
      // changed values...
      copy = element.getAttributes().copyAttributes();
  }

  /**
   * Redoes a change.
   *
   * @exception CannotRedoException if the change cannot be redone
   */
        public void redo() throws CannotRedoException {
      super.redo();
      MutableAttributeSet as = (MutableAttributeSet)element
                         .getAttributes();
      if(isReplacing)
    as.removeAttributes(as);
      as.addAttributes(newAttributes);
  }

  /**
   * Undoes a change.
   *
   * @exception CannotUndoException if the change cannot be undone
   */
        public void undo() throws CannotUndoException {
      super.undo();
      MutableAttributeSet as = (MutableAttributeSet)element.getAttributes();
      as.removeAttributes(as);
      as.addAttributes(copy);
  }

  // AttributeSet containing additional entries, must be non-mutable!
  protected AttributeSet newAttributes;
  // Copy of the AttributeSet the Element contained.
  protected AttributeSet copy;
  // true if all the attributes in the element were removed first.
  protected boolean isReplacing;
  // Efected Element.
  protected Element element;
    }

    /**
     * UndoableEdit for changing the resolve parent of an Element.
     */
    static class StyleChangeUndoableEdit extends AbstractUndoableEdit {
  public StyleChangeUndoableEdit(AbstractElement element,
               Style newStyle) {
      super();
      this.element = element;
      this.newStyle = newStyle;
      oldStyle = element.getResolveParent();
  }

  /**
   * Redoes a change.
   *
   * @exception CannotRedoException if the change cannot be redone
   */
        public void redo() throws CannotRedoException {
      super.redo();
      element.setResolveParent(newStyle);
  }

  /**
   * Undoes a change.
   *
   * @exception CannotUndoException if the change cannot be undone
   */
        public void undo() throws CannotUndoException {
      super.undo();
      element.setResolveParent(oldStyle);
  }

  /** Element to change resolve parent of. */
  protected AbstractElement element;
  /** New style. */
  protected Style newStyle;
  /** Old style, before setting newStyle. */
  protected AttributeSet oldStyle;
    }

    /**
     * Base class for style change handlers with support for stale objects detection.
     */
    abstract static class AbstractChangeHandler implements ChangeListener {
       
        /* This has an implicit reference to the handler object.  */
        private class DocReference extends WeakReference<DefaultStyledDocument> {
           
            DocReference(DefaultStyledDocument d, ReferenceQueue q) {
                super(d, q);
            }
           
            /**
             * Return a reference to the style change handler object.
             */
            ChangeListener getListener() {
                return AbstractChangeHandler.this;
            }
        }
       
        /** Class-specific reference queues.  */
        private final static Map<Class, ReferenceQueue> queueMap
                = new HashMap<Class, ReferenceQueue>();
       
        /** A weak reference to the document object.  */
        private DocReference doc;
       
        AbstractChangeHandler(DefaultStyledDocument d) {
            Class c = getClass();
            ReferenceQueue q;
            synchronized (queueMap) {
                q = queueMap.get(c);
                if (q == null) {
                    q = new ReferenceQueue();
                    queueMap.put(c, q);
                }
            }
            doc = new DocReference(d, q);
        }
       
        /**
         * Return a list of stale change listeners.
         *
         * A change listener becomes "stale" when its document is cleaned by GC.
         */
        static List<ChangeListener> getStaleListeners(ChangeListener l) {
            List<ChangeListener> staleListeners = new ArrayList<ChangeListener>();
            ReferenceQueue q = queueMap.get(l.getClass());
           
            if (q != null) {
                DocReference r;           
                synchronized (q) {
                    while ((r = (DocReference) q.poll()) != null) {
                        staleListeners.add(r.getListener());
                    }
                }
            }
           
            return staleListeners;
        }
       
        /**
         * The ChangeListener wrapper which guards against dead documents.
         */
        public void stateChanged(ChangeEvent e) {
            DefaultStyledDocument d = doc.get();
            if (d != null) {
                fireStateChanged(d, e);
            }
        }
       
        /** Run the actual class-specific stateChanged() method.  */
        abstract void fireStateChanged(DefaultStyledDocument d, ChangeEvent e);
    }

    /**
     * Added to all the Styles. When instances of this receive a
     * stateChanged method, styleChanged is invoked.
     */
    static class StyleChangeHandler extends AbstractChangeHandler {

        StyleChangeHandler(DefaultStyledDocument d) {
            super(d);
        }

        void fireStateChanged(DefaultStyledDocument d, ChangeEvent e) {
            Object source = e.getSource();
            if (source instanceof Style) {
                d.styleChanged((Style) source);
            } else {
                d.styleChanged(null);
            }
        }       
    }


    /**
     * Added to the StyleContext. When the StyleContext changes, this invokes
     * <code>updateStylesListeningTo</code>.
     */
    static class StyleContextChangeHandler extends AbstractChangeHandler {

        StyleContextChangeHandler(DefaultStyledDocument d) {
            super(d);
        }

        void fireStateChanged(DefaultStyledDocument d, ChangeEvent e) {
            d.updateStylesListeningTo();
  }
    }


    /**
     * When run this creates a change event for the complete document
     * and fires it.
     */
    class ChangeUpdateRunnable implements Runnable {
        boolean isPending = false;
       
  public void run() {
            synchronized(this) {
                isPending = false;
            }
           
      try {
    writeLock();
    DefaultDocumentEvent dde = new DefaultDocumentEvent(0,
                getLength(),
                DocumentEvent.EventType.CHANGE);
    dde.end();
    fireChangedUpdate(dde);
      } finally {
    writeUnlock();
      }
  }
    }
}



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