It is difficult to write undo/redo capabilities for SyntaxDocument

[Emerald214]

How to write undo/redo button for below SyntaxDocument? I read whole Chapter "Swing Undo Package" in "Core Swing Advance Programming" book but I still don't know how to do. (It's so difficult)

I knew that I must use CompoundEdit to merge element edit and attribute edit. I can't find out how to write undo/redo for this document because of its complication.

Do I have to use DefaultStyledDocument.AttributeUndoableEdit or AbstractDocument.ElementEdit?
My book has an only example about undoing/redoing on JTree, it doesn't have a clear example about styled document...

import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;
import java.util.*;
import javax.swing.*;
import javax.swing.text.*;

class SyntaxDocument extends DefaultStyledDocument
{
	private DefaultStyledDocument doc;
	private Element rootElement;

	private boolean multiLineComment;
	private MutableAttributeSet normal;
	private MutableAttributeSet keyword;
	private MutableAttributeSet comment;
	private MutableAttributeSet quote;

	private HashSet keywords;

	public SyntaxDocument()
	{
		doc = this;
		rootElement = doc.getDefaultRootElement();
		putProperty( DefaultEditorKit.EndOfLineStringProperty, "\n" );

		normal = new SimpleAttributeSet();
		StyleConstants.setForeground(normal, Color.black);

		comment = new SimpleAttributeSet();
		StyleConstants.setForeground(comment, Color.gray);
		StyleConstants.setItalic(comment, true);

		keyword = new SimpleAttributeSet();
		StyleConstants.setForeground(keyword, Color.blue);

		quote = new SimpleAttributeSet();
		StyleConstants.setForeground(quote, Color.red);

		keywords = new HashSet();
		keywords.add( "abstract" );
		keywords.add( "boolean" );
		keywords.add( "break" );
		keywords.add( "byte" );
		keywords.add( "byvalue" );
		keywords.add( "case" );
		keywords.add( "cast" );
		keywords.add( "catch" );
		keywords.add( "char" );
		keywords.add( "class" );
		keywords.add( "const" );
		keywords.add( "continue" );
		keywords.add( "default" );
		keywords.add( "do" );
		keywords.add( "double" );
		keywords.add( "else" );
		keywords.add( "extends" );
		keywords.add( "false" );
		keywords.add( "final" );
		keywords.add( "finally" );
		keywords.add( "float" );
		keywords.add( "for" );
		keywords.add( "future" );
		keywords.add( "generic" );
		keywords.add( "goto" );
		keywords.add( "if" );
		keywords.add( "implements" );
		keywords.add( "import" );
		keywords.add( "inner" );
		keywords.add( "instanceof" );
		keywords.add( "int" );
		keywords.add( "interface" );
		keywords.add( "long" );
		keywords.add( "native" );
		keywords.add( "new" );
		keywords.add( "null" );
		keywords.add( "operator" );
		keywords.add( "outer" );
		keywords.add( "package" );
		keywords.add( "private" );
		keywords.add( "protected" );
		keywords.add( "public" );
		keywords.add( "rest" );
		keywords.add( "return" );
		keywords.add( "short" );
		keywords.add( "static" );
		keywords.add( "super" );
		keywords.add( "switch" );
		keywords.add( "synchronized" );
		keywords.add( "this" );
		keywords.add( "throw" );
		keywords.add( "throws" );
		keywords.add( "transient" );
		keywords.add( "true" );
		keywords.add( "try" );
		keywords.add( "var" );
		keywords.add( "void" );
		keywords.add( "volatile" );
		keywords.add( "while" );
	}

	/*
	 *  Override to apply syntax highlighting after the document has been updated
	 */
	public void insertString(int offset, String str, AttributeSet a) throws BadLocationException
	{
		if (str.equals("{"))
			str = addMatchingBrace(offset);

		super.insertString(offset, str, a);
		processChangedLines(offset, str.length());
	}

	/*
	 *  Override to apply syntax highlighting after the document has been updated
	 */
	public void remove(int offset, int length) throws BadLocationException
	{
		super.remove(offset, length);
		processChangedLines(offset, 0);
	}

	/*
	 *  Determine how many lines have been changed,
	 *  then apply highlighting to each line
	 */
	public void processChangedLines(int offset, int length)
		throws BadLocationException
	{
		String content = doc.getText(0, doc.getLength());

		//  The lines affected by the latest document update

		int startLine = rootElement.getElementIndex( offset );
		int endLine = rootElement.getElementIndex( offset + length );

		//  Make sure all comment lines prior to the start line are commented
		//  and determine if the start line is still in a multi line comment

		setMultiLineComment( commentLinesBefore( content, startLine ) );

		//  Do the actual highlighting

		for (int i = startLine; i <= endLine; i++)
		{
			applyHighlighting(content, i);
		}

		//  Resolve highlighting to the next end multi line delimiter

		if (isMultiLineComment())
			commentLinesAfter(content, endLine);
		else
			highlightLinesAfter(content, endLine);
	}

	/*
	 *  Highlight lines when a multi line comment is still 'open'
	 *  (ie. matching end delimiter has not yet been encountered)
	 */
	private boolean commentLinesBefore(String content, int line)
	{
		int offset = rootElement.getElement( line ).getStartOffset();

		//  Start of comment not found, nothing to do

		int startDelimiter = lastIndexOf( content, getStartDelimiter(), offset - 2 );

		if (startDelimiter < 0)
			return false;

		//  Matching start/end of comment found, nothing to do

		int endDelimiter = indexOf( content, getEndDelimiter(), startDelimiter );

		if (endDelimiter < offset & endDelimiter != -1)
			return false;

		//  End of comment not found, highlight the lines

		doc.setCharacterAttributes(startDelimiter, offset - startDelimiter + 1, comment, false);
		return true;
	}

	/*
	 *  Highlight comment lines to matching end delimiter
	 */
	private void commentLinesAfter(String content, int line)
	{
		int offset = rootElement.getElement( line ).getEndOffset();

		//  End of comment not found, nothing to do

		int endDelimiter = indexOf( content, getEndDelimiter(), offset );

		if (endDelimiter < 0)
			return;

		//  Matching start/end of comment found, comment the lines

		int startDelimiter = lastIndexOf( content, getStartDelimiter(), endDelimiter );

		if (startDelimiter < 0 || startDelimiter <= offset)
		{
			doc.setCharacterAttributes(offset, endDelimiter - offset + 1, comment, false);
		}
	}

	/*
	 *  Highlight lines to start or end delimiter
	 */
	private void highlightLinesAfter(String content, int line)
		throws BadLocationException
	{
		int offset = rootElement.getElement( line ).getEndOffset();

		//  Start/End delimiter not found, nothing to do

		int startDelimiter = indexOf( content, getStartDelimiter(), offset );
		int endDelimiter = indexOf( content, getEndDelimiter(), offset );

		if (startDelimiter < 0)
			startDelimiter = content.length();

		if (endDelimiter < 0)
			endDelimiter = content.length();

		int delimiter = Math.min(startDelimiter, endDelimiter);

		if (delimiter < offset)
			return;

		//	Start/End delimiter found, reapply highlighting

		int endLine = rootElement.getElementIndex( delimiter );

		for (int i = line + 1; i < endLine; i++)
		{
			Element branch = rootElement.getElement( i );
			Element leaf = doc.getCharacterElement( branch.getStartOffset() );
			AttributeSet as = leaf.getAttributes();

			if ( as.isEqual(comment) )
				applyHighlighting(content, i);
		}
	}

	/*
	 *  Parse the line to determine the appropriate highlighting
	 */
	private void applyHighlighting(String content, int line)
		throws BadLocationException
	{
		int startOffset = rootElement.getElement( line ).getStartOffset();
		int endOffset = rootElement.getElement( line ).getEndOffset() - 1;

		int lineLength = endOffset - startOffset;
		int contentLength = content.length();

		if (endOffset >= contentLength)
			endOffset = contentLength - 1;

		//  check for multi line comments
		//  (always set the comment attribute for the entire line)

		if (endingMultiLineComment(content, startOffset, endOffset)
		||  isMultiLineComment()
		||  startingMultiLineComment(content, startOffset, endOffset) )
		{
			doc.setCharacterAttributes(startOffset, endOffset - startOffset + 1, comment, false);
			return;
		}

		//  set normal attributes for the line

		doc.setCharacterAttributes(startOffset, lineLength, normal, true);

		//  check for single line comment

		int index = content.indexOf(getSingleLineDelimiter(), startOffset);

		if ( (index > -1) && (index < endOffset) )
		{
			doc.setCharacterAttributes(index, endOffset - index + 1, comment, false);
			endOffset = index - 1;
		}

		//  check for tokens

		checkForTokens(content, startOffset, endOffset);
	}

	/*
	 *  Does this line contain the start delimiter
	 */
	private boolean startingMultiLineComment(String content, int startOffset, int endOffset)
		throws BadLocationException
	{
		int index = indexOf( content, getStartDelimiter(), startOffset );

		if ( (index < 0) || (index > endOffset) )
			return false;
		else
		{
			setMultiLineComment( true );
			return true;
		}
	}

	/*
	 *  Does this line contain the end delimiter
	 */
	private boolean endingMultiLineComment(String content, int startOffset, int endOffset)
		throws BadLocationException
	{
		int index = indexOf( content, getEndDelimiter(), startOffset );

		if ( (index < 0) || (index > endOffset) )
			return false;
		else
		{
			setMultiLineComment( false );
			return true;
		}
	}

	/*
	 *  We have found a start delimiter
	 *  and are still searching for the end delimiter
	 */
	private boolean isMultiLineComment()
	{
		return multiLineComment;
	}

	private void setMultiLineComment(boolean value)
	{
		multiLineComment = value;
	}

	/*
	 *	Parse the line for tokens to highlight
	 */
	private void checkForTokens(String content, int startOffset, int endOffset)
	{
		while (startOffset <= endOffset)
		{
			//  skip the delimiters to find the start of a new token

			while ( isDelimiter( content.substring(startOffset, startOffset + 1) ) )
			{
				if (startOffset < endOffset)
					startOffset++;
				else
					return;
			}

			//  Extract and process the entire token

			if ( isQuoteDelimiter( content.substring(startOffset, startOffset + 1) ) )
				startOffset = getQuoteToken(content, startOffset, endOffset);
			else
				startOffset = getOtherToken(content, startOffset, endOffset);
		}
	}

	/*
	 *
	 */
	private int getQuoteToken(String content, int startOffset, int endOffset)
	{
		String quoteDelimiter = content.substring(startOffset, startOffset + 1);
		String escapeString = getEscapeString(quoteDelimiter);

		int index;
		int endOfQuote = startOffset;

		//  skip over the escape quotes in this quote

		index = content.indexOf(escapeString, endOfQuote + 1);

		while ( (index > -1) && (index < endOffset) )
		{
			endOfQuote = index + 1;
			index = content.indexOf(escapeString, endOfQuote);
		}

		// now find the matching delimiter

		index = content.indexOf(quoteDelimiter, endOfQuote + 1);

		if ( (index < 0) || (index > endOffset) )
			endOfQuote = endOffset;
		else
			endOfQuote = index;

		doc.setCharacterAttributes(startOffset, endOfQuote - startOffset + 1, quote, false);

		return endOfQuote + 1;
	}

	/*
	 *
	 */
	private int getOtherToken(String content, int startOffset, int endOffset)
	{
		int endOfToken = startOffset + 1;

		while ( endOfToken <= endOffset )
		{
			if ( isDelimiter( content.substring(endOfToken, endOfToken + 1) ) )
				break;

			endOfToken++;
		}

		String token = content.substring(startOffset, endOfToken);

		if ( isKeyword( token ) )
		{
			doc.setCharacterAttributes(startOffset, endOfToken - startOffset, keyword, false);
		}

		return endOfToken + 1;
	}

	/*
	 *  Assume the needle will the found at the start/end of the line
	 */
	private int indexOf(String content, String needle, int offset)
	{
		int index;

		while ( (index = content.indexOf(needle, offset)) != -1 )
		{
			String text = getLine( content, index ).trim();

			if (text.startsWith(needle) || text.endsWith(needle))
				break;
			else
				offset = index + 1;
		}

		return index;
	}

	/*
	 *  Assume the needle will the found at the start/end of the line
	 */
	private int lastIndexOf(String content, String needle, int offset)
	{
		int index;

		while ( (index = content.lastIndexOf(needle, offset)) != -1 )
		{
			String text = getLine( content, index ).trim();

			if (text.startsWith(needle) || text.endsWith(needle))
				break;
			else
				offset = index - 1;
		}

		return index;
	}

	private String getLine(String content, int offset)
	{
		int line = rootElement.getElementIndex( offset );
		Element lineElement = rootElement.getElement( line );
		int start = lineElement.getStartOffset();
		int end = lineElement.getEndOffset();
		return content.substring(start, end - 1);
	}

	/*
	 *  Override for other languages
	 */
	protected boolean isDelimiter(String character)
	{
		String operands = ";:{}()[]+-/&#37;<=>!&|^~*";

		if (Character.isWhitespace( character.charAt(0) ) ||
			operands.indexOf(character) != -1 )
			return true;
		else
			return false;
	}

	/*
	 *  Override for other languages
	 */
	protected boolean isQuoteDelimiter(String character)
	{
		String quoteDelimiters = "\"'";

		if (quoteDelimiters.indexOf(character) < 0)
			return false;
		else
			return true;
	}

	/*
	 *  Override for other languages
	 */
	protected boolean isKeyword(String token)
	{
		return keywords.contains( token );
	}

	/*
	 *  Override for other languages
	 */
	protected String getStartDelimiter()
	{
		return "/*";
	}

	/*
	 *  Override for other languages
	 */
	protected String getEndDelimiter()
	{
		return "*/";
	}

	/*
	 *  Override for other languages
	 */
	protected String getSingleLineDelimiter()
	{
		return "//";
	}

	/*
	 *  Override for other languages
	 */
	protected String getEscapeString(String quoteDelimiter)
	{
		return "\\" + quoteDelimiter;
	}

	/*
	 *
	 */
	protected String addMatchingBrace(int offset) throws BadLocationException
	{
		StringBuffer whiteSpace = new StringBuffer();
		int line = rootElement.getElementIndex( offset );
		int i = rootElement.getElement(line).getStartOffset();

		while (true)
		{
			String temp = doc.getText(i, 1);

			if (temp.equals(" ") || temp.equals("\t"))
			{
				whiteSpace.append(temp);
				i++;
			}
			else
				break;
		}

		return "{\n" + whiteSpace.toString() + "\t\n" + whiteSpace.toString() + "}";
	}


	public static void main(String a[])
	{

		EditorKit editorKit = new StyledEditorKit()
		{
			public Document createDefaultDocument()
			{
				return new SyntaxDocument();
			}
		};

		final JEditorPane edit = new JEditorPane();
		edit.setEditorKitForContentType("text/java", editorKit);
		edit.setContentType("text/java");
//		edit.setEditorKit(new StyledEditorKit());
//		edit.setDocument(new SyntaxDocument());

		JButton button = new JButton("Load SyntaxDocument.java");
		button.addActionListener( new ActionListener()
		{
			public void actionPerformed(ActionEvent e)
			{
				try
				{
					FileInputStream fis = new FileInputStream( "SyntaxDocument.java" );
//					FileInputStream fis = new FileInputStream( "C:\\Java\\jdk1.4.1\\src\\javax\\swing\\JComponent.java" );
					edit.read( fis, null );
					edit.requestFocus();
				}
				catch(Exception e2) {}
			}
		});

		JFrame frame = new JFrame("Syntax Highlighting");
		frame.getContentPane().add( new JScrollPane(edit) );
		frame.getContentPane().add(button, BorderLayout.SOUTH);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setSize(800,300);
		frame.setVisible(true);
	}
}

[Emerald214]

The problem is my book doesn't have example code about undoing/redoing on styled document. I googled but there aren't any tutorials about it.

[keang]

Does this article help?

[Emerald214]

Thank you but it doesn't help me much. It is an example about undoing/redoing on plain text document.

[keang]

What it says is:

For PlainDocuments this involves keeping track of text insertions and removals, as well as any structural changes. For StyledDocuments, however, this involves keeping track of a much larger group of changes. Fortunately this work has been built into these document models for us

Now I've never tried doing this but, to me, the article suggests the functionality is built into the model and so the example given should work for either document model. Have you tried it?

[Emerald214]

That example code totally doesn't show how to build undo/redo funtionality in styled document because it uses JTextArea. (document of JTextArea is plain)
To undo in styled document, must use CompoundEdit...

This is exactly what I am finding:
http://stackoverflow.com/questions/1...-letter-a-time
(I don't know why noone answers me )

[dlorde]

(I don't know why noone answers me )

Probably because no-one who knows the answer has read your question. Have you tried the Sun Java forums?

The first 90% of the code accounts for the first 90% of the development time. The remaining 10% of the code accounts for the other 90% of the development time...
T. Cargill