final TextEditor activeEditor = getActiveEditor().get();
		final ISelection sourceSelection = activeEditor.getSelectionProvider().getSelection();
		if (sourceSelection instanceof ITextSelection) {
			if (isSelectionCommented((ITextSelection) sourceSelection)) {
				activeEditor.getSourceViewer().doOperation(TextViewer.STRIP_PREFIX);
			} else {
				activeEditor.getSourceViewer().doOperation(TextViewer.PREFIX);
			}
		}

	/** The prefixes. */
	private Map<String, String[]> prefixesMap = null;

	/**
	 * Check if ALL of the lines in the given <code>selection</code> are commented.
	 *
	 * @param selection
	 *            the <code>ITextSelection</code> to check
	 * @return true if all lines in the given <code>selection</code> are commented, else false
	 * @throws IllegalStateException
	 *             if the line number is invalid
	 */
	private boolean isSelectionCommented(final ITextSelection selection) throws IllegalStateException {

		final int startLine = selection.getStartLine();
		final int endLine = selection.getEndLine();

		for (int i = startLine; i <= endLine; i++) {
			try {
				final IDocument document = getActiveEditor().get().getDocumentProvider().getDocument(null);
				final IRegion region = document.getLineInformation(i);
				String line = document.get(region.getOffset(), region.getLength());
				line = StringUtils.stripToEmpty(line);
				final Collection<String[]> c = prefixesMap.values();
				boolean isComment = false;
				for (final String[] a : c) {
					for (final String s : a) {
						if (line.startsWith(s)) {
							// line i is commented
							isComment = true;
						}
					}
				}
				if (!isComment) {
					return false;
				}
			} catch (final BadLocationException e) {
				throw new IllegalStateException(e);
			}
		}
		return true;
	}

	/**
	 * Evaluate the prefixes used for commenting a line and store it in this {@link #prefixesMap}.
	 */
	private void setPrefixMap() {
		if (prefixesMap != null) {
			return;
		}
		final TextEditor activeEditor = getActiveEditor().get();
		final String[] types = activeEditor.getSourceViewerConfiguration().getConfiguredContentTypes(
				activeEditor.getSourceViewer());
		final Map<String, String[]> pMap = new HashMap<>(types.length);
		for (final String type : types) {
			String[] prefixes = activeEditor.getSourceViewerConfiguration().getDefaultPrefixes(
					activeEditor.getSourceViewer(), type);
			if (prefixes != null && prefixes.length > 0) {
				int emptyPrefixes = 0;
				for (final String prefixe : prefixes) {
					if (prefixe.length() == 0) {
						emptyPrefixes++;
					}
				}

				if (emptyPrefixes > 0) {
					final String[] nonemptyPrefixes = new String[prefixes.length - emptyPrefixes];
					for (int j = 0, k = 0; j < prefixes.length; j++) {
						final String prefix = prefixes[j];
						if (prefix.length() != 0) {
							nonemptyPrefixes[k] = prefix;
							k++;
						}
					}
					prefixes = nonemptyPrefixes;
				}
				pMap.put(type, prefixes);
			}
		}
		prefixesMap = pMap;
	}

	/** {@inheritDoc} */
	@Override
	protected void execute(final ISelection selection) throws ExecutionException {
		// evaluate the prefixes used for comments
		setPrefixMap();
		final TextEditor activeEditor = getActiveEditor().get();
		final ISelection sourceSelection = activeEditor.getSelectionProvider().getSelection();
		if (sourceSelection instanceof ITextSelection) {
			if (isSelectionCommented((ITextSelection) sourceSelection)) {
				activeEditor.getSourceViewer().doOperation(TextViewer.STRIP_PREFIX);
			} else {
				activeEditor.getSourceViewer().doOperation(TextViewer.PREFIX);
			}
		}
	}