org.eclipse.jdt.debug.ui/ui/org/eclipse/jdt/internal/debug/ui/JDISourceViewer.java - jdt/eclipse.jdt.debug - Git at Google

 /*******************************************************************************
  * Copyright (c) 2000, 2016 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
  * which accompanies this distribution, and is available at
  * https://www.eclipse.org/legal/epl-2.0/
  *
  * SPDX-License-Identifier: EPL-2.0
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.jdt.internal.debug.ui;


 import org.eclipse.jdt.internal.debug.ui.display.DisplayViewerConfiguration;
 import org.eclipse.jdt.ui.PreferenceConstants;
 import org.eclipse.jdt.ui.text.IJavaPartitions;
 import org.eclipse.jface.preference.IPreferenceStore;
 import org.eclipse.jface.preference.PreferenceConverter;
 import org.eclipse.jface.resource.JFaceResources;
 import org.eclipse.jface.text.BadLocationException;
 import org.eclipse.jface.text.IDocument;
 import org.eclipse.jface.text.IRegion;
 import org.eclipse.jface.text.ITypedRegion;
 import org.eclipse.jface.text.TextUtilities;
 import org.eclipse.jface.text.contentassist.ContentAssistant;
 import org.eclipse.jface.text.contentassist.IContentAssistant;
 import org.eclipse.jface.text.source.IOverviewRuler;
 import org.eclipse.jface.text.source.IVerticalRuler;
 import org.eclipse.jface.text.source.SourceViewer;
 import org.eclipse.jface.text.source.SourceViewerConfiguration;
 import org.eclipse.jface.util.IPropertyChangeListener;
 import org.eclipse.jface.util.PropertyChangeEvent;
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.custom.BidiSegmentEvent;
 import org.eclipse.swt.custom.BidiSegmentListener;
 import org.eclipse.swt.custom.StyledText;
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.Font;
 import org.eclipse.swt.graphics.FontData;
 import org.eclipse.swt.graphics.Point;
 import org.eclipse.swt.graphics.RGB;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.ui.texteditor.AbstractTextEditor;

 import com.ibm.icu.text.Bidi;

 /**
  * A source viewer configured to display Java source. This
  * viewer obeys the font and color preferences specified in
  * the Java UI plugin.
  */
 public class JDISourceViewer extends SourceViewer implements IPropertyChangeListener {

 	/**
 	 * BIDI delimtiers.
 	 *
 	 * @since 3.4
 	 */
 	private static final String BIDI_DELIMITERS= "[ \\p{Punct}&&[^_]]"; //$NON-NLS-1$


 	private Font fFont;
 	private Color fBackgroundColor;
 	private Color fForegroundColor;
 	private IPreferenceStore fStore;
 	private DisplayViewerConfiguration fConfiguration;


 	public JDISourceViewer(Composite parent, IVerticalRuler ruler, int styles) {
 		this(parent, ruler, null, false, styles);
 	}


 	public JDISourceViewer(Composite parent, IVerticalRuler ruler, IOverviewRuler overviewRuler, boolean isOverviewRulerVisible, int styles) {
 		super(parent, ruler, overviewRuler, isOverviewRulerVisible, styles);
 		StyledText text= this.getTextWidget();
 		final int baseLevel= (styles & SWT.RIGHT_TO_LEFT) != 0 ? Bidi.DIRECTION_RIGHT_TO_LEFT : Bidi.DIRECTION_LEFT_TO_RIGHT;
 		text.addBidiSegmentListener(new  BidiSegmentListener() {
 			@Override
 			public void lineGetSegments(BidiSegmentEvent event) {
 				try {
 					event.segments= getBidiLineSegments(getDocument(), baseLevel, widgetOffset2ModelOffset(event.lineOffset), event.lineText);
 				} catch (BadLocationException x) {
 					// ignore
 				}
 			}
 		});
 	}

 	/**
 	 * Updates the viewer's font to match the preferences.
 	 */
 	private void updateViewerFont() {
 		IPreferenceStore store= getPreferenceStore();
 		if (store != null) {
 			FontData data= null;
 			if (store.contains(PreferenceConstants.EDITOR_TEXT_FONT) && !store.isDefault(PreferenceConstants.EDITOR_TEXT_FONT)) {
 				data= PreferenceConverter.getFontData(store, PreferenceConstants.EDITOR_TEXT_FONT);
 			} else {
 				data = PreferenceConverter.getDefaultFontData(store, PreferenceConstants.EDITOR_TEXT_FONT);
 			}
 			if (data != null) {
 				Font font= new Font(getTextWidget().getDisplay(), data);
 				applyFont(font);
 				if (getFont() != null) {
 					getFont().dispose();
 				}
 				setFont(font);
 				return;
 			}
 		}
 		// if all the preferences failed
 		applyFont(JFaceResources.getTextFont());
 	}

 	/**
 	 * Sets the current font.
 	 *
 	 * @param font the new font
 	 */
 	private void setFont(Font font) {
 		fFont= font;
 	}

 	/**
 	 * Returns the current font.
 	 *
 	 * @return the current font
 	 */
 	private Font getFont() {
 		return fFont;
 	}

 	/**
 	 * Sets the font for the given viewer sustaining selection and scroll position.
 	 *
 	 * @param font the font
 	 */
 	private void applyFont(Font font) {
 		IDocument doc= getDocument();
 		if (doc != null && doc.getLength() > 0) {
 			Point selection= getSelectedRange();
 			int topIndex= getTopIndex();

 			StyledText styledText= getTextWidget();
 			styledText.setRedraw(false);

 			styledText.setFont(font);
 			setSelectedRange(selection.x , selection.y);
 			setTopIndex(topIndex);

 			styledText.setRedraw(true);
 		} else {
 			getTextWidget().setFont(font);
 		}
 	}

 	/**
 	 * Updates the given viewer's colors to match the preferences.
 	 */
 	public void updateViewerColors() {
 		IPreferenceStore store= getPreferenceStore();
 		if (store != null) {
 			StyledText styledText= getTextWidget();
 			Color color= store.getBoolean(AbstractTextEditor.PREFERENCE_COLOR_FOREGROUND_SYSTEM_DEFAULT)
 				? null
 				: createColor(store, AbstractTextEditor.PREFERENCE_COLOR_FOREGROUND, styledText.getDisplay());
 			styledText.setForeground(color);
 			if (getForegroundColor() != null) {
 				getForegroundColor().dispose();
 			}
 			setForegroundColor(color);

 			color= store.getBoolean(AbstractTextEditor.PREFERENCE_COLOR_BACKGROUND_SYSTEM_DEFAULT)
 				? null
 				: createColor(store, AbstractTextEditor.PREFERENCE_COLOR_BACKGROUND, styledText.getDisplay());
 			styledText.setBackground(color);
 			if (getBackgroundColor() != null) {
 				getBackgroundColor().dispose();
 			}
 			setBackgroundColor(color);
 		}
 	}

 	/**
 	 * Creates a color from the information stored in the given preference store.
 	 * Returns <code>null</code> if there is no such information available.
 	 */
 	private Color createColor(IPreferenceStore store, String key, Display display) {
 		RGB rgb= null;
 		if (store.contains(key)) {
 			if (store.isDefault(key)) {
 				rgb= PreferenceConverter.getDefaultColor(store, key);
 			} else {
 				rgb= PreferenceConverter.getColor(store, key);
 			}
 			if (rgb != null) {
 				return new Color(display, rgb);
 			}
 		}
 		return null;
 	}

 	/**
 	 * Returns the current background color.
 	 *
 	 * @return the current background color
 	 */
 	protected Color getBackgroundColor() {
 		return fBackgroundColor;
 	}

 	/**
 	 * Sets the current background color.
 	 *
 	 * @param backgroundColor the new background color
 	 */
 	protected void setBackgroundColor(Color backgroundColor) {
 		fBackgroundColor = backgroundColor;
 	}

 	/**
 	 * Returns the current foreground color.
 	 *
 	 * @return the current foreground color
 	 */
 	protected Color getForegroundColor() {
 		return fForegroundColor;
 	}

 	/**
 	 * Sets the current foreground color.
 	 *
 	 * @param foregroundColor the new foreground color
 	 */
 	protected void setForegroundColor(Color foregroundColor) {
 		fForegroundColor = foregroundColor;
 	}

 	/**
 	 * @see IPropertyChangeListener#propertyChange(PropertyChangeEvent)
 	 */
 	@Override
 	public void propertyChange(PropertyChangeEvent event) {
 		IContentAssistant assistant= getContentAssistant();
 		if (assistant instanceof ContentAssistant) {
 			JDIContentAssistPreference.changeConfiguration((ContentAssistant) assistant, event);
 		}
 		String property= event.getProperty();

 		if (PreferenceConstants.EDITOR_TEXT_FONT.equals(property)) {
 			updateViewerFont();
 		}
 		if (AbstractTextEditor.PREFERENCE_COLOR_FOREGROUND.equals(property) || AbstractTextEditor.PREFERENCE_COLOR_FOREGROUND_SYSTEM_DEFAULT.equals(property) ||
 			AbstractTextEditor.PREFERENCE_COLOR_BACKGROUND.equals(property) ||	AbstractTextEditor.PREFERENCE_COLOR_BACKGROUND_SYSTEM_DEFAULT.equals(property)) {
 			updateViewerColors();
 		}
 		if (fConfiguration != null) {
 			if (fConfiguration.affectsTextPresentation(event)) {
 				fConfiguration.handlePropertyChangeEvent(event);
 				invalidateTextPresentation();
 			}
 		}
 	}

 	/**
 	 * Returns the current content assistant.
 	 *
 	 * @return the current content assistant
 	 */
 	public IContentAssistant getContentAssistant() {
 		return fContentAssistant;
 	}

 	/**
 	 * Disposes the system resources currently in use by this viewer.
 	 */
 	public void dispose() {
 		if (getFont() != null) {
 			getFont().dispose();
 			setFont(null);
 		}
 		if (getBackgroundColor() != null) {
 			getBackgroundColor().dispose();
 			setBackgroundColor(null);
 		}
 		if (getForegroundColor() != null) {
 			getForegroundColor().dispose();
 			setForegroundColor(null);
 		}
 		if (fStore != null) {
 			fStore.removePropertyChangeListener(this);
 			fStore = null;
 		}
 	}

 	/* (non-Javadoc)
 	 * @see org.eclipse.jface.text.source.SourceViewer#configure(org.eclipse.jface.text.source.SourceViewerConfiguration)
 	 */
 	@Override
 	public void configure(SourceViewerConfiguration configuration) {
 		super.configure(configuration);
 		if (fStore != null) {
 			fStore.removePropertyChangeListener(this);
 			fStore = null;
 		}
 		if (configuration instanceof DisplayViewerConfiguration) {
 			fConfiguration = (DisplayViewerConfiguration) configuration;
 			fStore = fConfiguration.getTextPreferenceStore();
 			fStore.addPropertyChangeListener(this);
 		}
 		updateViewerFont();
 		updateViewerColors();
 	}

 	/**
 	 * Returns the preference store used to configure this source viewer or
 	 * <code>null</code> if none;
 	 */
 	private IPreferenceStore getPreferenceStore() {
 		return fStore;
 	}

 	/**
 	 * Returns a segmentation of the line of the given document appropriate for Bidi rendering.
 	 *
 	 * @param document the document
 	 * @param baseLevel the base level of the line
 	 * @param lineStart the offset of the line
 	 * @param lineText Text of the line to retrieve Bidi segments for
 	 * @return the line's Bidi segmentation
 	 * @throws BadLocationException in case lineOffset is not valid in document
 	 */
 	protected static int[] getBidiLineSegments(IDocument document, int baseLevel, int lineStart, String lineText) throws BadLocationException {

 		if (lineText == null || document == null) {
 			return null;
 		}

 		int lineLength= lineText.length();
 		if (lineLength <= 2) {
 			return null;
 		}

 		// Have ICU compute embedding levels. Consume these levels to reduce
 		// the Bidi impact, by creating selective segments (preceding
 		// character runs with a level mismatching the base level).
 		// XXX: Alternatively, we could apply TextLayout. Pros would be full
 		// synchronization with the underlying StyledText's (i.e. native) Bidi
 		// implementation. Cons are performance penalty because of
 		// unavailability of such methods as isLeftToRight and getLevels.

 		Bidi bidi= new Bidi(lineText, baseLevel);
 		if (bidi.isLeftToRight()) {
 			// Bail out if this is not Bidi text.
 			return null;
 		}

 		IRegion line= document.getLineInformationOfOffset(lineStart);
 		ITypedRegion[] linePartitioning= TextUtilities.computePartitioning(document, IJavaPartitions.JAVA_PARTITIONING, lineStart, line.getLength(), false);
 		if (linePartitioning == null || linePartitioning.length < 1) {
 			return null;
 		}

 		int segmentIndex= 1;
 		int[] segments= new int[lineLength + 1];
 		byte[] levels= bidi.getLevels();
 		int nPartitions= linePartitioning.length;
 		for (int partitionIndex= 0; partitionIndex < nPartitions; partitionIndex++) {

 			ITypedRegion partition= linePartitioning[partitionIndex];
 			int lineOffset= partition.getOffset() - lineStart;
 			//Assert.isTrue(lineOffset >= 0 && lineOffset < lineLength);

 			if (lineOffset > 0 && isMismatchingLevel(levels[lineOffset], baseLevel) && isMismatchingLevel(levels[lineOffset - 1], baseLevel)) {
 				// Indicate a Bidi segment at the partition start - provided
 				// levels of both character at the current offset and its
 				// preceding character mismatch the base paragraph level.
 				// Partition end will be covered either by the start of the next
 				// partition, a delimiter inside a next partition, or end of line.
 				segments[segmentIndex++]= lineOffset;
 			}
 			if (IDocument.DEFAULT_CONTENT_TYPE.equals(partition.getType())) {
 				int partitionEnd= Math.min(lineLength, lineOffset + partition.getLength());
 				while (++lineOffset < partitionEnd) {
 					if (isMismatchingLevel(levels[lineOffset], baseLevel) && String.valueOf(lineText.charAt(lineOffset)).matches(BIDI_DELIMITERS)) {
 						// For default content types, indicate a segment before
 						// a delimiting character with a mismatching embedding
 						// level.
 						segments[segmentIndex++]= lineOffset;
 					}
 				}
 			}
 		}
 		if (segmentIndex <= 1) {
 			return null;
 		}

 		segments[0]= 0;
 		if (segments[segmentIndex - 1] != lineLength) {
 			segments[segmentIndex++]= lineLength;
 		}

 		if (segmentIndex == segments.length) {
 			return segments;
 		}

 		int[] newSegments= new int[segmentIndex];
 		System.arraycopy(segments, 0, newSegments, 0, segmentIndex);
 		return newSegments;
 	}

 	/**
 	 * Checks if the given embedding level is consistent with the base level.
 	 *
 	 * @param level Character embedding level to check.
 	 * @param baseLevel Base level (direction) of the text.
 	 * @return <code>true</code> if the character level is odd and the base level is even OR the character level is even and the base level is odd, and return <code>false</code> otherwise.
 	 *
 	 * @since 3.4
 	 */
 	private static boolean isMismatchingLevel(int level, int baseLevel) {
 		return ((level ^ baseLevel) & 1) != 0;
 	}

 }
	/*******************************************************************************
	* Copyright (c) 2000, 2016 IBM Corporation and others.
	*
	* This program and the accompanying materials
	* are made available under the terms of the Eclipse Public License 2.0
	* which accompanies this distribution, and is available at
	* https://www.eclipse.org/legal/epl-2.0/
	*
	* SPDX-License-Identifier: EPL-2.0
	*
	* Contributors:
	* IBM Corporation - initial API and implementation
	*******************************************************************************/
	package org.eclipse.jdt.internal.debug.ui;


	import org.eclipse.jdt.internal.debug.ui.display.DisplayViewerConfiguration;
	import org.eclipse.jdt.ui.PreferenceConstants;
	import org.eclipse.jdt.ui.text.IJavaPartitions;
	import org.eclipse.jface.preference.IPreferenceStore;
	import org.eclipse.jface.preference.PreferenceConverter;
	import org.eclipse.jface.resource.JFaceResources;
	import org.eclipse.jface.text.BadLocationException;
	import org.eclipse.jface.text.IDocument;
	import org.eclipse.jface.text.IRegion;
	import org.eclipse.jface.text.ITypedRegion;
	import org.eclipse.jface.text.TextUtilities;
	import org.eclipse.jface.text.contentassist.ContentAssistant;
	import org.eclipse.jface.text.contentassist.IContentAssistant;
	import org.eclipse.jface.text.source.IOverviewRuler;
	import org.eclipse.jface.text.source.IVerticalRuler;
	import org.eclipse.jface.text.source.SourceViewer;
	import org.eclipse.jface.text.source.SourceViewerConfiguration;
	import org.eclipse.jface.util.IPropertyChangeListener;
	import org.eclipse.jface.util.PropertyChangeEvent;
	import org.eclipse.swt.SWT;
	import org.eclipse.swt.custom.BidiSegmentEvent;
	import org.eclipse.swt.custom.BidiSegmentListener;
	import org.eclipse.swt.custom.StyledText;
	import org.eclipse.swt.graphics.Color;
	import org.eclipse.swt.graphics.Font;
	import org.eclipse.swt.graphics.FontData;
	import org.eclipse.swt.graphics.Point;
	import org.eclipse.swt.graphics.RGB;
	import org.eclipse.swt.widgets.Composite;
	import org.eclipse.swt.widgets.Display;
	import org.eclipse.ui.texteditor.AbstractTextEditor;

	import com.ibm.icu.text.Bidi;

	/**
	* A source viewer configured to display Java source. This
	* viewer obeys the font and color preferences specified in
	* the Java UI plugin.
	*/
	public class JDISourceViewer extends SourceViewer implements IPropertyChangeListener {

	/**
	* BIDI delimtiers.
	*
	* @since 3.4
	*/
	private static final String BIDI_DELIMITERS= "[ \\p{Punct}&&[^_]]"; //$NON-NLS-1$


	private Font fFont;
	private Color fBackgroundColor;
	private Color fForegroundColor;
	private IPreferenceStore fStore;
	private DisplayViewerConfiguration fConfiguration;


	public JDISourceViewer(Composite parent, IVerticalRuler ruler, int styles) {
	this(parent, ruler, null, false, styles);
	}


	public JDISourceViewer(Composite parent, IVerticalRuler ruler, IOverviewRuler overviewRuler, boolean isOverviewRulerVisible, int styles) {
	super(parent, ruler, overviewRuler, isOverviewRulerVisible, styles);
	StyledText text= this.getTextWidget();
	final int baseLevel= (styles & SWT.RIGHT_TO_LEFT) != 0 ? Bidi.DIRECTION_RIGHT_TO_LEFT : Bidi.DIRECTION_LEFT_TO_RIGHT;
	text.addBidiSegmentListener(new BidiSegmentListener() {
	@Override
	public void lineGetSegments(BidiSegmentEvent event) {
	try {
	event.segments= getBidiLineSegments(getDocument(), baseLevel, widgetOffset2ModelOffset(event.lineOffset), event.lineText);
	} catch (BadLocationException x) {
	// ignore
	}
	}
	});
	}

	/**
	* Updates the viewer's font to match the preferences.
	*/
	private void updateViewerFont() {
	IPreferenceStore store= getPreferenceStore();
	if (store != null) {
	FontData data= null;
	if (store.contains(PreferenceConstants.EDITOR_TEXT_FONT) && !store.isDefault(PreferenceConstants.EDITOR_TEXT_FONT)) {
	data= PreferenceConverter.getFontData(store, PreferenceConstants.EDITOR_TEXT_FONT);
	} else {
	data = PreferenceConverter.getDefaultFontData(store, PreferenceConstants.EDITOR_TEXT_FONT);
	}
	if (data != null) {
	Font font= new Font(getTextWidget().getDisplay(), data);
	applyFont(font);
	if (getFont() != null) {
	getFont().dispose();
	}
	setFont(font);
	return;
	}
	}
	// if all the preferences failed
	applyFont(JFaceResources.getTextFont());
	}

	/**
	* Sets the current font.
	*
	* @param font the new font
	*/
	private void setFont(Font font) {
	fFont= font;
	}

	/**
	* Returns the current font.
	*
	* @return the current font
	*/
	private Font getFont() {
	return fFont;
	}

	/**
	* Sets the font for the given viewer sustaining selection and scroll position.
	*
	* @param font the font
	*/
	private void applyFont(Font font) {
	IDocument doc= getDocument();
	if (doc != null && doc.getLength() > 0) {
	Point selection= getSelectedRange();
	int topIndex= getTopIndex();

	StyledText styledText= getTextWidget();
	styledText.setRedraw(false);

	styledText.setFont(font);
	setSelectedRange(selection.x , selection.y);
	setTopIndex(topIndex);

	styledText.setRedraw(true);
	} else {
	getTextWidget().setFont(font);
	}
	}

	/**
	* Updates the given viewer's colors to match the preferences.
	*/
	public void updateViewerColors() {
	IPreferenceStore store= getPreferenceStore();
	if (store != null) {
	StyledText styledText= getTextWidget();
	Color color= store.getBoolean(AbstractTextEditor.PREFERENCE_COLOR_FOREGROUND_SYSTEM_DEFAULT)
	? null
	: createColor(store, AbstractTextEditor.PREFERENCE_COLOR_FOREGROUND, styledText.getDisplay());
	styledText.setForeground(color);
	if (getForegroundColor() != null) {
	getForegroundColor().dispose();
	}
	setForegroundColor(color);

	color= store.getBoolean(AbstractTextEditor.PREFERENCE_COLOR_BACKGROUND_SYSTEM_DEFAULT)
	? null
	: createColor(store, AbstractTextEditor.PREFERENCE_COLOR_BACKGROUND, styledText.getDisplay());
	styledText.setBackground(color);
	if (getBackgroundColor() != null) {
	getBackgroundColor().dispose();
	}
	setBackgroundColor(color);
	}
	}

	/**
	* Creates a color from the information stored in the given preference store.
	* Returns <code>null</code> if there is no such information available.
	*/
	private Color createColor(IPreferenceStore store, String key, Display display) {
	RGB rgb= null;
	if (store.contains(key)) {
	if (store.isDefault(key)) {
	rgb= PreferenceConverter.getDefaultColor(store, key);
	} else {
	rgb= PreferenceConverter.getColor(store, key);
	}
	if (rgb != null) {
	return new Color(display, rgb);
	}
	}
	return null;
	}

	/**
	* Returns the current background color.
	*
	* @return the current background color
	*/
	protected Color getBackgroundColor() {
	return fBackgroundColor;
	}

	/**
	* Sets the current background color.
	*
	* @param backgroundColor the new background color
	*/
	protected void setBackgroundColor(Color backgroundColor) {
	fBackgroundColor = backgroundColor;
	}

	/**
	* Returns the current foreground color.
	*
	* @return the current foreground color
	*/
	protected Color getForegroundColor() {
	return fForegroundColor;
	}

	/**
	* Sets the current foreground color.
	*
	* @param foregroundColor the new foreground color
	*/
	protected void setForegroundColor(Color foregroundColor) {
	fForegroundColor = foregroundColor;
	}

	/**
	* @see IPropertyChangeListener#propertyChange(PropertyChangeEvent)
	*/
	@Override
	public void propertyChange(PropertyChangeEvent event) {
	IContentAssistant assistant= getContentAssistant();
	if (assistant instanceof ContentAssistant) {
	JDIContentAssistPreference.changeConfiguration((ContentAssistant) assistant, event);
	}
	String property= event.getProperty();

	if (PreferenceConstants.EDITOR_TEXT_FONT.equals(property)) {
	updateViewerFont();
	}
	if (AbstractTextEditor.PREFERENCE_COLOR_FOREGROUND.equals(property) \|\| AbstractTextEditor.PREFERENCE_COLOR_FOREGROUND_SYSTEM_DEFAULT.equals(property) \|\|
	AbstractTextEditor.PREFERENCE_COLOR_BACKGROUND.equals(property) \|\| AbstractTextEditor.PREFERENCE_COLOR_BACKGROUND_SYSTEM_DEFAULT.equals(property)) {
	updateViewerColors();
	}
	if (fConfiguration != null) {
	if (fConfiguration.affectsTextPresentation(event)) {
	fConfiguration.handlePropertyChangeEvent(event);
	invalidateTextPresentation();
	}
	}
	}

	/**
	* Returns the current content assistant.
	*
	* @return the current content assistant
	*/
	public IContentAssistant getContentAssistant() {
	return fContentAssistant;
	}

	/**
	* Disposes the system resources currently in use by this viewer.
	*/
	public void dispose() {
	if (getFont() != null) {
	getFont().dispose();
	setFont(null);
	}
	if (getBackgroundColor() != null) {
	getBackgroundColor().dispose();
	setBackgroundColor(null);
	}
	if (getForegroundColor() != null) {
	getForegroundColor().dispose();
	setForegroundColor(null);
	}
	if (fStore != null) {
	fStore.removePropertyChangeListener(this);
	fStore = null;
	}
	}

	/* (non-Javadoc)
	* @see org.eclipse.jface.text.source.SourceViewer#configure(org.eclipse.jface.text.source.SourceViewerConfiguration)
	*/
	@Override
	public void configure(SourceViewerConfiguration configuration) {
	super.configure(configuration);
	if (fStore != null) {
	fStore.removePropertyChangeListener(this);
	fStore = null;
	}
	if (configuration instanceof DisplayViewerConfiguration) {
	fConfiguration = (DisplayViewerConfiguration) configuration;
	fStore = fConfiguration.getTextPreferenceStore();
	fStore.addPropertyChangeListener(this);
	}
	updateViewerFont();
	updateViewerColors();
	}

	/**
	* Returns the preference store used to configure this source viewer or
	* <code>null</code> if none;
	*/
	private IPreferenceStore getPreferenceStore() {
	return fStore;
	}

	/**
	* Returns a segmentation of the line of the given document appropriate for Bidi rendering.
	*
	* @param document the document
	* @param baseLevel the base level of the line
	* @param lineStart the offset of the line
	* @param lineText Text of the line to retrieve Bidi segments for
	* @return the line's Bidi segmentation
	* @throws BadLocationException in case lineOffset is not valid in document
	*/
	protected static int[] getBidiLineSegments(IDocument document, int baseLevel, int lineStart, String lineText) throws BadLocationException {

	if (lineText == null \|\| document == null) {
	return null;
	}

	int lineLength= lineText.length();
	if (lineLength <= 2) {
	return null;
	}

	// Have ICU compute embedding levels. Consume these levels to reduce
	// the Bidi impact, by creating selective segments (preceding
	// character runs with a level mismatching the base level).
	// XXX: Alternatively, we could apply TextLayout. Pros would be full
	// synchronization with the underlying StyledText's (i.e. native) Bidi
	// implementation. Cons are performance penalty because of
	// unavailability of such methods as isLeftToRight and getLevels.

	Bidi bidi= new Bidi(lineText, baseLevel);
	if (bidi.isLeftToRight()) {
	// Bail out if this is not Bidi text.
	return null;
	}

	IRegion line= document.getLineInformationOfOffset(lineStart);
	ITypedRegion[] linePartitioning= TextUtilities.computePartitioning(document, IJavaPartitions.JAVA_PARTITIONING, lineStart, line.getLength(), false);
	if (linePartitioning == null \|\| linePartitioning.length < 1) {
	return null;
	}

	int segmentIndex= 1;
	int[] segments= new int[lineLength + 1];
	byte[] levels= bidi.getLevels();
	int nPartitions= linePartitioning.length;
	for (int partitionIndex= 0; partitionIndex < nPartitions; partitionIndex++) {

	ITypedRegion partition= linePartitioning[partitionIndex];
	int lineOffset= partition.getOffset() - lineStart;
	//Assert.isTrue(lineOffset >= 0 && lineOffset < lineLength);

	if (lineOffset > 0 && isMismatchingLevel(levels[lineOffset], baseLevel) && isMismatchingLevel(levels[lineOffset - 1], baseLevel)) {
	// Indicate a Bidi segment at the partition start - provided
	// levels of both character at the current offset and its
	// preceding character mismatch the base paragraph level.
	// Partition end will be covered either by the start of the next
	// partition, a delimiter inside a next partition, or end of line.
	segments[segmentIndex++]= lineOffset;
	}
	if (IDocument.DEFAULT_CONTENT_TYPE.equals(partition.getType())) {
	int partitionEnd= Math.min(lineLength, lineOffset + partition.getLength());
	while (++lineOffset < partitionEnd) {
	if (isMismatchingLevel(levels[lineOffset], baseLevel) && String.valueOf(lineText.charAt(lineOffset)).matches(BIDI_DELIMITERS)) {
	// For default content types, indicate a segment before
	// a delimiting character with a mismatching embedding
	// level.
	segments[segmentIndex++]= lineOffset;
	}
	}
	}
	}
	if (segmentIndex <= 1) {
	return null;
	}

	segments[0]= 0;
	if (segments[segmentIndex - 1] != lineLength) {
	segments[segmentIndex++]= lineLength;
	}

	if (segmentIndex == segments.length) {
	return segments;
	}

	int[] newSegments= new int[segmentIndex];
	System.arraycopy(segments, 0, newSegments, 0, segmentIndex);
	return newSegments;
	}

	/**
	* Checks if the given embedding level is consistent with the base level.
	*
	* @param level Character embedding level to check.
	* @param baseLevel Base level (direction) of the text.
	* @return <code>true</code> if the character level is odd and the base level is even OR the character level is even and the base level is odd, and return <code>false</code> otherwise.
	*
	* @since 3.4
	*/
	private static boolean isMismatchingLevel(int level, int baseLevel) {
	return ((level ^ baseLevel) & 1) != 0;
	}

	}