ltk/org.eclipse.statet.ltk.ui/src/org/eclipse/statet/ltk/ui/sourceediting/actions/ToggleCommentHandler.java - statet/org.eclipse.statet-ltk - Git at Google

 /*=============================================================================#
  # Copyright (c) 2014, 2020 Stephan Wahlbrink and others.
  #
  # This program and the accompanying materials are made available under the
  # terms of the Eclipse Public License 2.0 which is available at
  # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
  # which is available at https://www.apache.org/licenses/LICENSE-2.0.
  #
  # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
  #
  # Contributors:
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/

 package org.eclipse.statet.ltk.ui.sourceediting.actions;

 import java.util.IdentityHashMap;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;

 import org.eclipse.core.commands.AbstractHandler;
 import org.eclipse.core.commands.ExecutionEvent;
 import org.eclipse.core.commands.ExecutionException;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;
 import org.eclipse.jface.text.AbstractDocument;
 import org.eclipse.jface.text.BadLocationException;
 import org.eclipse.jface.text.BadPartitioningException;
 import org.eclipse.jface.text.DocumentRewriteSession;
 import org.eclipse.jface.text.DocumentRewriteSessionType;
 import org.eclipse.jface.text.IDocument;
 import org.eclipse.jface.text.IRegion;
 import org.eclipse.jface.text.ITextOperationTarget;
 import org.eclipse.jface.text.ITextSelection;
 import org.eclipse.jface.text.ITypedRegion;
 import org.eclipse.jface.text.TextUtilities;
 import org.eclipse.jface.viewers.ISelection;
 import org.eclipse.swt.custom.BusyIndicator;
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.swt.widgets.Shell;
 import org.eclipse.text.edits.DeleteEdit;
 import org.eclipse.text.edits.InsertEdit;
 import org.eclipse.text.edits.MultiTextEdit;
 import org.eclipse.text.edits.TextEdit;
 import org.eclipse.ui.statushandlers.StatusManager;
 import org.eclipse.ui.texteditor.IEditorStatusLine;

 import org.eclipse.statet.ecommons.ui.SharedUIResources;

 import org.eclipse.statet.internal.ltk.ui.EditingMessages;
 import org.eclipse.statet.ltk.ui.EditorUtils;
 import org.eclipse.statet.ltk.ui.sourceediting.SourceEditor1;
 import org.eclipse.statet.ltk.ui.sourceediting.SourceEditorViewer;


 public class ToggleCommentHandler extends AbstractHandler {


 	private static final ConcurrentHashMap<String, Pattern> DEFAULT_PREFIX_MAP= new ConcurrentHashMap<>();

 	protected static Pattern getDefaultPrefixPattern(final String prefix) {
 		Pattern pattern= DEFAULT_PREFIX_MAP.get(prefix);
 		if (pattern == null) {
 			pattern= Pattern.compile("^[ \\t]*(" + Pattern.quote(prefix) + ")"); //$NON-NLS-1$ //$NON-NLS-2$
 			DEFAULT_PREFIX_MAP.putIfAbsent(prefix, pattern);
 		}
 		return pattern;
 	}

 	protected static final Pattern HTML_SPACE_PREFIX_PATTERN= Pattern.compile("^[ \\t]*(" + Pattern.quote("<!--") + " ?)"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
 	protected static final Pattern HTML_SPACE_POSTFIX_PATTERN= Pattern.compile("( ?" + Pattern.quote("-->") + "[ \\t]*)$"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$


 	private final SourceEditor1 editor;

 	/** The text operation target */
 	private ITextOperationTarget operationTarget;

 	private final Map<String, String[]> contentTypePrefixes= new IdentityHashMap<>();


 	public ToggleCommentHandler(final SourceEditor1 editor) {
 		this.editor= editor;

 		setBaseEnabled(false);
 	}


 	protected SourceEditor1 getEditor() {
 		return this.editor;
 	}

 	@Override
 	public void setEnabled(final Object evaluationContext) {
 		if (this.editor.getViewer() instanceof SourceEditorViewer
 				&& !this.editor.isEditorInputModifiable()) {
 			setBaseEnabled(false);
 			return;
 		}

 		if (this.operationTarget == null) {
 			this.operationTarget= this.editor.getAdapter(ITextOperationTarget.class);
 		}
 		setBaseEnabled(this.operationTarget != null
 				&& this.operationTarget.canDoOperation(ITextOperationTarget.PREFIX)
 				&& this.operationTarget.canDoOperation(ITextOperationTarget.STRIP_PREFIX) );
 	}

 	private ITextSelection getSelection() {
 		final ISelection selection= this.editor.getSelectionProvider().getSelection();
 		return (selection instanceof ITextSelection) ? (ITextSelection) selection : null;
 	}

 	@Override
 	public Object execute(final ExecutionEvent event) throws ExecutionException {
 		if (!this.editor.validateEditorInputState() || !isEnabled()) {
 			return null;
 		}

 		final ITextSelection selection= getSelection();
 		final AbstractDocument document= (AbstractDocument) this.editor.getViewer().getDocument();
 		final int operationCode= (isSelectionCommented(document, selection)) ?
 				ITextOperationTarget.STRIP_PREFIX : ITextOperationTarget.PREFIX;

 		final Shell shell= this.editor.getSite().getShell();
 		if (!this.operationTarget.canDoOperation(operationCode)) {
 			signalError();
 			return null;
 		}

 		Display display= null;
 		if (shell != null && !shell.isDisposed()) {
 			display= shell.getDisplay();
 		}

 		BusyIndicator.showWhile(display, new Runnable() {
 			@Override
 			public void run() {
 				ToggleCommentHandler.this.run(document, selection, operationCode);
 			}
 		});
 		return null;
 	}

 	protected void run(final AbstractDocument document, final ITextSelection selection,
 			final int operationCode) {
 		doRunOperation(operationCode);
 	}

 	protected void doRunOperation(final int operationCode) {
 		this.operationTarget.doOperation(operationCode);
 	}


 	protected String[] getPrefixes(final String contentType) {
 		String[] prefixes= this.contentTypePrefixes.get(contentType);
 		if (prefixes == null) {
 			prefixes= ((SourceEditorViewer) this.editor.getViewer()).getDefaultPrefixes(contentType);
 			if (prefixes == null) {
 				prefixes= new String[0];
 			}
 			else {
 				int numEmpty= 0;
 				for (int i= 0; i < prefixes.length; i++) {
 					if (prefixes[i].isEmpty()) {
 						numEmpty++;
 					}
 				}
 				if (numEmpty > 0) {
 					final String[] nonemptyPrefixes= new String[prefixes.length - numEmpty];
 					for (int i= 0, j= 0; i < prefixes.length; i++) {
 						final String prefix= prefixes[i];
 						if (!prefix.isEmpty()) {
 							nonemptyPrefixes[j++]= prefix;
 						}
 					}
 					prefixes= nonemptyPrefixes;
 				}
 			}
 			this.contentTypePrefixes.put(contentType, prefixes);
 		}
 		return prefixes;
 	}

 	protected Pattern getPrefixPattern(final String contentType, final String prefix) {
 		return getDefaultPrefixPattern(prefix);
 	}

 	protected Pattern getPostfixPattern(final String contentType, final String prefix) {
 		return null;
 	}

 	/**
 	 * Is the given selection single-line commented?
 	 *
 	 * @param selection Selection to check
 	 * @return <code>true</code> iff all selected lines are commented
 	 * @throws BadPartitioningException
 	 */
 	private boolean isSelectionCommented(final AbstractDocument document, final ITextSelection selection) {
 		if (selection.getStartLine() < 0 || selection.getEndLine() < 0) {
 			return false;
 		}

 		try {
 			final IRegion block= EditorUtils.getTextBlockFromSelection(document,
 					selection.getOffset(), selection.getLength() );
 			final ITypedRegion[] regions= document.computePartitioning(
 					this.editor.getDocumentContentInfo().getPartitioning(),
 					block.getOffset(), block.getLength(), false );

 			final int[] lines= new int[regions.length * 2]; // [startline, endline, startline, endline, ...]
 			for (int i= 0, j= 0; i < regions.length; i++, j+= 2) {
 				// start line of region
 				lines[j]= getFirstCompleteLineOfRegion(document, regions[i]);
 				// end line of region
 				final int length= regions[i].getLength();
 				int offset= regions[i].getOffset() + length;
 				if (length > 0) {
 					offset--;
 				}
 				lines[j + 1]= (lines[j] == -1) ? -1 : document.getLineOfOffset(offset);
 			}

 			// Perform the check
 			for (int i= 0, j= 0; i < regions.length; i++, j+= 2) {
 				final String[] prefixes= getPrefixes(regions[i].getType());
 				if (prefixes != null && prefixes.length > 0 && lines[j] >= 0 && lines[j + 1] >= 0) {
 					if (!isBlockCommented(lines[j], lines[j + 1], prefixes, document)) {
 						return false;
 					}
 				}
 			}
 			return true;
 		}
 		catch (final BadLocationException | BadPartitioningException e) {
 			log(e);
 		}
 		return false;
 	}

 	/**
 	 * Determines whether each line is prefixed by one of the prefixes.
 	 *
 	 * @param startLine Start line in document
 	 * @param endLine End line in document
 	 * @param prefixes Possible comment prefixes
 	 * @param document The document
 	 * @return <code>true</code> iff each line from <code>startLine</code>
 	 *     to and including <code>endLine</code> is prepended by one
 	 *     of the <code>prefixes</code>, ignoring whitespace at the
 	 *     begin of line
 	 */
 	private boolean isBlockCommented(final int startLine, final int endLine, final String[] prefixes,
 			final IDocument document) {
 		try {
 			// check for occurrences of prefixes in the given lines
 			for (int i= startLine; i <= endLine; i++) {

 				final IRegion lineInfo= document.getLineInformation(i);
 				final String text= document.get(lineInfo.getOffset(), lineInfo.getLength());

 				final int[] found= TextUtilities.indexOf(prefixes, text, 0);

 				if (found[0] == -1) {
 					// found a line which is not commented
 					return false;
 				}

 				final String beforePrefix= text.substring(0, found[0]);
 				if (beforePrefix.trim().length() != 0) {
 					// found a line which is not commented
 					return false;
 				}
 			}
 			return true;
 		}
 		catch (final BadLocationException e) {
 			log(e);
 		}
 		return false;
 	}

 	/**
 	 * Returns the index of the first line whose start offset is in the given text range.
 	 *
 	 * @param document The document
 	 * @param region the text range in characters where to find the line
 	 * @return the first line whose start index is in the given range, -1 if there is no such line
 	 * @throws BadLocationException
 	 */
 	protected int getFirstCompleteLineOfRegion(final IDocument document, final IRegion region) throws BadLocationException {
 		final int startLine= document.getLineOfOffset(region.getOffset());

 		int offset= document.getLineOffset(startLine);
 		if (offset >= region.getOffset()) {
 			return startLine;
 		}
 		offset= document.getLineOffset(startLine + 1);
 		return (offset > region.getOffset() + region.getLength() ? -1 : startLine + 1);
 	}

 	protected void doPrefix(final AbstractDocument document, final IRegion region,
 			final String prefix)
 			throws BadLocationException, BadPartitioningException {
 		final int startLine= document.getLineOfOffset(region.getOffset());
 		final int stopLine= (region.getLength() > 0) ?
 				document.getLineOfOffset(region.getOffset()+region.getLength()-1) :
 				startLine;

 		final MultiTextEdit multi= new MultiTextEdit(region.getOffset(), region.getLength());
 		for (int line= startLine; line <= stopLine; line++) {
 			multi.addChild(new InsertEdit(document.getLineOffset(line), prefix));
 		}

 		{	final DocumentRewriteSession rewriteSession= document.startRewriteSession(
 					DocumentRewriteSessionType.STRICTLY_SEQUENTIAL );
 			try {
 				multi.apply(document, TextEdit.NONE);
 			}
 			finally {
 				document.stopRewriteSession(rewriteSession);
 			}
 		}
 	}

 	protected void doPrefix(final AbstractDocument document, final IRegion region,
 			final String prefix, final String postfix)
 			throws BadLocationException, BadPartitioningException {
 		final int startLine= document.getLineOfOffset(region.getOffset());
 		final int stopLine= (region.getLength() > 0) ?
 				document.getLineOfOffset(region.getOffset()+region.getLength()-1) :
 				startLine;

 		final MultiTextEdit multi= new MultiTextEdit(region.getOffset(), region.getLength());
 		for (int line= startLine; line <= stopLine; line++) {
 			final IRegion lineInfo= document.getLineInformation(line);
 			multi.addChild(new InsertEdit(lineInfo.getOffset(), prefix));
 			multi.addChild(new InsertEdit(lineInfo.getOffset() + lineInfo.getLength(), postfix));
 		}

 		{	final DocumentRewriteSession rewriteSession= document.startRewriteSession(
 					DocumentRewriteSessionType.STRICTLY_SEQUENTIAL );
 			try {
 				multi.apply(document, TextEdit.NONE);
 			}
 			finally {
 				document.stopRewriteSession(rewriteSession);
 			}
 		}
 	}

 	protected void doStripPrefix(final AbstractDocument document, final IRegion region)
 			throws BadLocationException, BadPartitioningException {
 		final int startLine= document.getLineOfOffset(region.getOffset());
 		final int stopLine= (region.getLength() > 0) ?
 				document.getLineOfOffset(region.getOffset()+region.getLength()-1) :
 				startLine;

 		final MultiTextEdit multi= new MultiTextEdit(region.getOffset(), region.getLength());
 		for (int line= startLine; line <= stopLine; line++) {
 			final IRegion lineInfo= document.getLineInformation(line);
 			final String contentType= document.getContentType(
 					this.editor.getDocumentContentInfo().getPartitioning(),
 					lineInfo.getOffset(), false );

 			final String[] prefixes= getPrefixes(contentType);
 			final String text= document.get(lineInfo.getOffset(), lineInfo.getLength());
 			final int[] found= TextUtilities.indexOf(prefixes, text, 0);
 			assert (found[0] >= 0);

 			{	final Pattern pattern= getPrefixPattern(contentType, prefixes[found[1]]);
 				if (pattern != null) {
 					final Matcher matcher= pattern.matcher(text);
 					matcher.reset(text);
 					if (matcher.find()) {
 						multi.addChild(new DeleteEdit(
 								lineInfo.getOffset() + matcher.start(1),
 								matcher.end(1) - matcher.start(1) ));
 					}
 				}
 				else {
 					multi.addChild(new DeleteEdit(
 							lineInfo.getOffset() + found[0],
 							prefixes[found[1]].length() ));
 				}
 			}
 			{	final Pattern pattern= getPostfixPattern(contentType, prefixes[found[1]]);
 				if (pattern != null) {
 					final Matcher matcher= pattern.matcher(text);
 					if (matcher.find()) {
 						multi.addChild(new DeleteEdit(
 								lineInfo.getOffset() + matcher.start(1),
 								matcher.end(1) - matcher.start(1) ));
 					}
 				}
 			}
 		}

 		{	final DocumentRewriteSession rewriteSession= document.startRewriteSession(
 					DocumentRewriteSessionType.STRICTLY_SEQUENTIAL );
 			try {
 				multi.apply(document, TextEdit.NONE);
 			}
 			finally {
 				document.stopRewriteSession(rewriteSession);
 			}
 		}
 	}


 	protected void signalError() {
 		final IEditorStatusLine statusLine= this.editor.getAdapter(IEditorStatusLine.class);
 		statusLine.setMessage(true, EditingMessages.ToggleCommentAction_error, null);
 		this.editor.getViewer().getTextWidget().getDisplay().beep();
 	}

 	protected void log(final Exception e) {
 		StatusManager.getManager().handle(new Status(IStatus.ERROR, SharedUIResources.BUNDLE_ID, 0,
 				"An error ocurred when executing toggle comment operation.", e ), StatusManager.LOG);
 	}

 }
	/*=============================================================================#
	# Copyright (c) 2014, 2020 Stephan Wahlbrink and others.
	#
	# This program and the accompanying materials are made available under the
	# terms of the Eclipse Public License 2.0 which is available at
	# https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
	# which is available at https://www.apache.org/licenses/LICENSE-2.0.
	#
	# SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
	#
	# Contributors:
	# Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
	#=============================================================================*/

	package org.eclipse.statet.ltk.ui.sourceediting.actions;

	import java.util.IdentityHashMap;
	import java.util.Map;
	import java.util.concurrent.ConcurrentHashMap;
	import java.util.regex.Matcher;
	import java.util.regex.Pattern;

	import org.eclipse.core.commands.AbstractHandler;
	import org.eclipse.core.commands.ExecutionEvent;
	import org.eclipse.core.commands.ExecutionException;
	import org.eclipse.core.runtime.IStatus;
	import org.eclipse.core.runtime.Status;
	import org.eclipse.jface.text.AbstractDocument;
	import org.eclipse.jface.text.BadLocationException;
	import org.eclipse.jface.text.BadPartitioningException;
	import org.eclipse.jface.text.DocumentRewriteSession;
	import org.eclipse.jface.text.DocumentRewriteSessionType;
	import org.eclipse.jface.text.IDocument;
	import org.eclipse.jface.text.IRegion;
	import org.eclipse.jface.text.ITextOperationTarget;
	import org.eclipse.jface.text.ITextSelection;
	import org.eclipse.jface.text.ITypedRegion;
	import org.eclipse.jface.text.TextUtilities;
	import org.eclipse.jface.viewers.ISelection;
	import org.eclipse.swt.custom.BusyIndicator;
	import org.eclipse.swt.widgets.Display;
	import org.eclipse.swt.widgets.Shell;
	import org.eclipse.text.edits.DeleteEdit;
	import org.eclipse.text.edits.InsertEdit;
	import org.eclipse.text.edits.MultiTextEdit;
	import org.eclipse.text.edits.TextEdit;
	import org.eclipse.ui.statushandlers.StatusManager;
	import org.eclipse.ui.texteditor.IEditorStatusLine;

	import org.eclipse.statet.ecommons.ui.SharedUIResources;

	import org.eclipse.statet.internal.ltk.ui.EditingMessages;
	import org.eclipse.statet.ltk.ui.EditorUtils;
	import org.eclipse.statet.ltk.ui.sourceediting.SourceEditor1;
	import org.eclipse.statet.ltk.ui.sourceediting.SourceEditorViewer;


	public class ToggleCommentHandler extends AbstractHandler {


	private static final ConcurrentHashMap<String, Pattern> DEFAULT_PREFIX_MAP= new ConcurrentHashMap<>();

	protected static Pattern getDefaultPrefixPattern(final String prefix) {
	Pattern pattern= DEFAULT_PREFIX_MAP.get(prefix);
	if (pattern == null) {
	pattern= Pattern.compile("^[ \\t]*(" + Pattern.quote(prefix) + ")"); //$NON-NLS-1$ //$NON-NLS-2$
	DEFAULT_PREFIX_MAP.putIfAbsent(prefix, pattern);
	}
	return pattern;
	}

	protected static final Pattern HTML_SPACE_PREFIX_PATTERN= Pattern.compile("^[ \\t]*(" + Pattern.quote("<!--") + " ?)"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
	protected static final Pattern HTML_SPACE_POSTFIX_PATTERN= Pattern.compile("( ?" + Pattern.quote("-->") + "[ \\t]*)$"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$


	private final SourceEditor1 editor;

	/** The text operation target */
	private ITextOperationTarget operationTarget;

	private final Map<String, String[]> contentTypePrefixes= new IdentityHashMap<>();


	public ToggleCommentHandler(final SourceEditor1 editor) {
	this.editor= editor;

	setBaseEnabled(false);
	}


	protected SourceEditor1 getEditor() {
	return this.editor;
	}

	@Override
	public void setEnabled(final Object evaluationContext) {
	if (this.editor.getViewer() instanceof SourceEditorViewer
	&& !this.editor.isEditorInputModifiable()) {
	setBaseEnabled(false);
	return;
	}

	if (this.operationTarget == null) {
	this.operationTarget= this.editor.getAdapter(ITextOperationTarget.class);
	}
	setBaseEnabled(this.operationTarget != null
	&& this.operationTarget.canDoOperation(ITextOperationTarget.PREFIX)
	&& this.operationTarget.canDoOperation(ITextOperationTarget.STRIP_PREFIX) );
	}

	private ITextSelection getSelection() {
	final ISelection selection= this.editor.getSelectionProvider().getSelection();
	return (selection instanceof ITextSelection) ? (ITextSelection) selection : null;
	}

	@Override
	public Object execute(final ExecutionEvent event) throws ExecutionException {
	if (!this.editor.validateEditorInputState() \|\| !isEnabled()) {
	return null;
	}

	final ITextSelection selection= getSelection();
	final AbstractDocument document= (AbstractDocument) this.editor.getViewer().getDocument();
	final int operationCode= (isSelectionCommented(document, selection)) ?
	ITextOperationTarget.STRIP_PREFIX : ITextOperationTarget.PREFIX;

	final Shell shell= this.editor.getSite().getShell();
	if (!this.operationTarget.canDoOperation(operationCode)) {
	signalError();
	return null;
	}

	Display display= null;
	if (shell != null && !shell.isDisposed()) {
	display= shell.getDisplay();
	}

	BusyIndicator.showWhile(display, new Runnable() {
	@Override
	public void run() {
	ToggleCommentHandler.this.run(document, selection, operationCode);
	}
	});
	return null;
	}

	protected void run(final AbstractDocument document, final ITextSelection selection,
	final int operationCode) {
	doRunOperation(operationCode);
	}

	protected void doRunOperation(final int operationCode) {
	this.operationTarget.doOperation(operationCode);
	}


	protected String[] getPrefixes(final String contentType) {
	String[] prefixes= this.contentTypePrefixes.get(contentType);
	if (prefixes == null) {
	prefixes= ((SourceEditorViewer) this.editor.getViewer()).getDefaultPrefixes(contentType);
	if (prefixes == null) {
	prefixes= new String[0];
	}
	else {
	int numEmpty= 0;
	for (int i= 0; i < prefixes.length; i++) {
	if (prefixes[i].isEmpty()) {
	numEmpty++;
	}
	}
	if (numEmpty > 0) {
	final String[] nonemptyPrefixes= new String[prefixes.length - numEmpty];
	for (int i= 0, j= 0; i < prefixes.length; i++) {
	final String prefix= prefixes[i];
	if (!prefix.isEmpty()) {
	nonemptyPrefixes[j++]= prefix;
	}
	}
	prefixes= nonemptyPrefixes;
	}
	}
	this.contentTypePrefixes.put(contentType, prefixes);
	}
	return prefixes;
	}

	protected Pattern getPrefixPattern(final String contentType, final String prefix) {
	return getDefaultPrefixPattern(prefix);
	}

	protected Pattern getPostfixPattern(final String contentType, final String prefix) {
	return null;
	}

	/**
	* Is the given selection single-line commented?
	*
	* @param selection Selection to check
	* @return <code>true</code> iff all selected lines are commented
	* @throws BadPartitioningException
	*/
	private boolean isSelectionCommented(final AbstractDocument document, final ITextSelection selection) {
	if (selection.getStartLine() < 0 \|\| selection.getEndLine() < 0) {
	return false;
	}

	try {
	final IRegion block= EditorUtils.getTextBlockFromSelection(document,
	selection.getOffset(), selection.getLength() );
	final ITypedRegion[] regions= document.computePartitioning(
	this.editor.getDocumentContentInfo().getPartitioning(),
	block.getOffset(), block.getLength(), false );

	final int[] lines= new int[regions.length * 2]; // [startline, endline, startline, endline, ...]
	for (int i= 0, j= 0; i < regions.length; i++, j+= 2) {
	// start line of region
	lines[j]= getFirstCompleteLineOfRegion(document, regions[i]);
	// end line of region
	final int length= regions[i].getLength();
	int offset= regions[i].getOffset() + length;
	if (length > 0) {
	offset--;
	}
	lines[j + 1]= (lines[j] == -1) ? -1 : document.getLineOfOffset(offset);
	}

	// Perform the check
	for (int i= 0, j= 0; i < regions.length; i++, j+= 2) {
	final String[] prefixes= getPrefixes(regions[i].getType());
	if (prefixes != null && prefixes.length > 0 && lines[j] >= 0 && lines[j + 1] >= 0) {
	if (!isBlockCommented(lines[j], lines[j + 1], prefixes, document)) {
	return false;
	}
	}
	}
	return true;
	}
	catch (final BadLocationException \| BadPartitioningException e) {
	log(e);
	}
	return false;
	}

	/**
	* Determines whether each line is prefixed by one of the prefixes.
	*
	* @param startLine Start line in document
	* @param endLine End line in document
	* @param prefixes Possible comment prefixes
	* @param document The document
	* @return <code>true</code> iff each line from <code>startLine</code>
	* to and including <code>endLine</code> is prepended by one
	* of the <code>prefixes</code>, ignoring whitespace at the
	* begin of line
	*/
	private boolean isBlockCommented(final int startLine, final int endLine, final String[] prefixes,
	final IDocument document) {
	try {
	// check for occurrences of prefixes in the given lines
	for (int i= startLine; i <= endLine; i++) {

	final IRegion lineInfo= document.getLineInformation(i);
	final String text= document.get(lineInfo.getOffset(), lineInfo.getLength());

	final int[] found= TextUtilities.indexOf(prefixes, text, 0);

	if (found[0] == -1) {
	// found a line which is not commented
	return false;
	}

	final String beforePrefix= text.substring(0, found[0]);
	if (beforePrefix.trim().length() != 0) {
	// found a line which is not commented
	return false;
	}
	}
	return true;
	}
	catch (final BadLocationException e) {
	log(e);
	}
	return false;
	}

	/**
	* Returns the index of the first line whose start offset is in the given text range.
	*
	* @param document The document
	* @param region the text range in characters where to find the line
	* @return the first line whose start index is in the given range, -1 if there is no such line
	* @throws BadLocationException
	*/
	protected int getFirstCompleteLineOfRegion(final IDocument document, final IRegion region) throws BadLocationException {
	final int startLine= document.getLineOfOffset(region.getOffset());

	int offset= document.getLineOffset(startLine);
	if (offset >= region.getOffset()) {
	return startLine;
	}
	offset= document.getLineOffset(startLine + 1);
	return (offset > region.getOffset() + region.getLength() ? -1 : startLine + 1);
	}

	protected void doPrefix(final AbstractDocument document, final IRegion region,
	final String prefix)
	throws BadLocationException, BadPartitioningException {
	final int startLine= document.getLineOfOffset(region.getOffset());
	final int stopLine= (region.getLength() > 0) ?
	document.getLineOfOffset(region.getOffset()+region.getLength()-1) :
	startLine;

	final MultiTextEdit multi= new MultiTextEdit(region.getOffset(), region.getLength());
	for (int line= startLine; line <= stopLine; line++) {
	multi.addChild(new InsertEdit(document.getLineOffset(line), prefix));
	}

	{ final DocumentRewriteSession rewriteSession= document.startRewriteSession(
	DocumentRewriteSessionType.STRICTLY_SEQUENTIAL );
	try {
	multi.apply(document, TextEdit.NONE);
	}
	finally {
	document.stopRewriteSession(rewriteSession);
	}
	}
	}

	protected void doPrefix(final AbstractDocument document, final IRegion region,
	final String prefix, final String postfix)
	throws BadLocationException, BadPartitioningException {
	final int startLine= document.getLineOfOffset(region.getOffset());
	final int stopLine= (region.getLength() > 0) ?
	document.getLineOfOffset(region.getOffset()+region.getLength()-1) :
	startLine;

	final MultiTextEdit multi= new MultiTextEdit(region.getOffset(), region.getLength());
	for (int line= startLine; line <= stopLine; line++) {
	final IRegion lineInfo= document.getLineInformation(line);
	multi.addChild(new InsertEdit(lineInfo.getOffset(), prefix));
	multi.addChild(new InsertEdit(lineInfo.getOffset() + lineInfo.getLength(), postfix));
	}

	{ final DocumentRewriteSession rewriteSession= document.startRewriteSession(
	DocumentRewriteSessionType.STRICTLY_SEQUENTIAL );
	try {
	multi.apply(document, TextEdit.NONE);
	}
	finally {
	document.stopRewriteSession(rewriteSession);
	}
	}
	}

	protected void doStripPrefix(final AbstractDocument document, final IRegion region)
	throws BadLocationException, BadPartitioningException {
	final int startLine= document.getLineOfOffset(region.getOffset());
	final int stopLine= (region.getLength() > 0) ?
	document.getLineOfOffset(region.getOffset()+region.getLength()-1) :
	startLine;

	final MultiTextEdit multi= new MultiTextEdit(region.getOffset(), region.getLength());
	for (int line= startLine; line <= stopLine; line++) {
	final IRegion lineInfo= document.getLineInformation(line);
	final String contentType= document.getContentType(
	this.editor.getDocumentContentInfo().getPartitioning(),
	lineInfo.getOffset(), false );

	final String[] prefixes= getPrefixes(contentType);
	final String text= document.get(lineInfo.getOffset(), lineInfo.getLength());
	final int[] found= TextUtilities.indexOf(prefixes, text, 0);
	assert (found[0] >= 0);

	{ final Pattern pattern= getPrefixPattern(contentType, prefixes[found[1]]);
	if (pattern != null) {
	final Matcher matcher= pattern.matcher(text);
	matcher.reset(text);
	if (matcher.find()) {
	multi.addChild(new DeleteEdit(
	lineInfo.getOffset() + matcher.start(1),
	matcher.end(1) - matcher.start(1) ));
	}
	}
	else {
	multi.addChild(new DeleteEdit(
	lineInfo.getOffset() + found[0],
	prefixes[found[1]].length() ));
	}
	}
	{ final Pattern pattern= getPostfixPattern(contentType, prefixes[found[1]]);
	if (pattern != null) {
	final Matcher matcher= pattern.matcher(text);
	if (matcher.find()) {
	multi.addChild(new DeleteEdit(
	lineInfo.getOffset() + matcher.start(1),
	matcher.end(1) - matcher.start(1) ));
	}
	}
	}
	}

	{ final DocumentRewriteSession rewriteSession= document.startRewriteSession(
	DocumentRewriteSessionType.STRICTLY_SEQUENTIAL );
	try {
	multi.apply(document, TextEdit.NONE);
	}
	finally {
	document.stopRewriteSession(rewriteSession);
	}
	}
	}


	protected void signalError() {
	final IEditorStatusLine statusLine= this.editor.getAdapter(IEditorStatusLine.class);
	statusLine.setMessage(true, EditingMessages.ToggleCommentAction_error, null);
	this.editor.getViewer().getTextWidget().getDisplay().beep();
	}

	protected void log(final Exception e) {
	StatusManager.getManager().handle(new Status(IStatus.ERROR, SharedUIResources.BUNDLE_ID, 0,
	"An error ocurred when executing toggle comment operation.", e ), StatusManager.LOG);
	}

	}