bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/extensions/NavigatorContentExtension.java - platform/eclipse.platform.ui - Git at Google

 /*******************************************************************************
  * Copyright (c) 2003, 2007 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal.navigator.extensions;

 import java.util.Iterator;
 import java.util.LinkedHashSet;
 import java.util.Set;

 import org.eclipse.core.runtime.Assert;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.ISafeRunnable;
 import org.eclipse.core.runtime.SafeRunner;
 import org.eclipse.jface.viewers.ILabelProvider;
 import org.eclipse.jface.viewers.ILabelProviderListener;
 import org.eclipse.jface.viewers.ITreeContentProvider;
 import org.eclipse.ui.IMemento;
 import org.eclipse.ui.internal.navigator.NavigatorContentService;
 import org.eclipse.ui.internal.navigator.NavigatorPlugin;
 import org.eclipse.ui.navigator.ICommonContentProvider;
 import org.eclipse.ui.navigator.ICommonLabelProvider;
 import org.eclipse.ui.navigator.IExtensionStateModel;
 import org.eclipse.ui.navigator.IMementoAware;
 import org.eclipse.ui.navigator.INavigatorContentDescriptor;
 import org.eclipse.ui.navigator.INavigatorContentExtension;

 /**
  * <p>
  * <strong>EXPERIMENTAL</strong>. This class or interface has been added as
  * part of a work in progress. There is a guarantee neither that this API will
  * work nor that it will remain the same. Please do not use this API without
  * consulting with the Platform/UI team.
  * </p>
  *
  * @since 3.2
  */
 public class NavigatorContentExtension implements IMementoAware,
 		INavigatorContentExtension {

 	private static final NavigatorContentExtension[] NO_EXTENSIONS = new NavigatorContentExtension[0];

 	private NavigatorContentService contentService;

 	private NavigatorContentDescriptor descriptor;

 	private ICommonContentProvider contentProvider;

 	private ICommonLabelProvider labelProvider;

 	private boolean labelProviderInitializationFailed = false;

 	private boolean contentProviderInitializationFailed = false;

 	private boolean isDisposed = false;

 	private IMemento appliedMemento;

 	private StructuredViewerManager viewerManager;

 	/**
 	 * Create an object to manage the instantiated elements from the extension.
 	 *
 	 * @param aDescriptor
 	 *            The descriptor that knows how to create elements and knows the
 	 *            id of the extension
 	 * @param aContentService
 	 *            The content service that will manage this extension
 	 * @param aViewerManager
 	 *            The viewer manager that knows how to initialize the content
 	 *            provider created by this extension.
 	 */
 	public NavigatorContentExtension(NavigatorContentDescriptor aDescriptor,
 			NavigatorContentService aContentService,
 			StructuredViewerManager aViewerManager) {
 		super();
 		Assert.isNotNull(aDescriptor);

 		descriptor = aDescriptor;
 		contentService = aContentService;
 		viewerManager = aViewerManager;
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.ui.internal.navigator.extensions.INavigatorContentExtension#getId()
 	 */
 	public String getId() {
 		return descriptor.getId();
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.ui.internal.navigator.extensions.INavigatorContentExtension#getDescriptor()
 	 */
 	public INavigatorContentDescriptor getDescriptor() {
 		return descriptor;
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.ui.navigator.INavigatorContentExtension#getContentProvider()
 	 */
 	public ITreeContentProvider getContentProvider() {

 		ITreeContentProvider provider = internalGetContentProvider();
 		if (provider != SkeletonTreeContentProvider.INSTANCE) {
 			return ((SafeDelegateTreeContentProvider) provider)
 					.getDelegateContentProvider();
 		}
 		return provider;
 	}

 	/**
 	 *
 	 * @return The internal content provider that is wrapped by this extension.
 	 */
 	public ITreeContentProvider internalGetContentProvider() {
 		if (contentProvider != null || contentProviderInitializationFailed) {
 			return contentProvider;
 		}
 		synchronized (this) {
 			try {
 				if (contentProvider == null) {
 					ITreeContentProvider treeContentProvider = descriptor
 							.createContentProvider();
 					if (treeContentProvider != null) {
 						contentProvider = new SafeDelegateTreeContentProvider(
 								treeContentProvider, descriptor, contentService);
 						contentProvider.init(new CommonContentExtensionSite(
 								getId(), contentService, appliedMemento));
 						viewerManager.initialize(contentProvider);
 					} else {
 						contentProvider = SkeletonTreeContentProvider.INSTANCE;
 					}
 				}
 			} catch (CoreException e) {
 				contentProviderInitializationFailed = true;
 				e.printStackTrace();
 			} catch (RuntimeException e) {
 				contentProviderInitializationFailed = true;
 				e.printStackTrace();
 			}
 			if (contentProviderInitializationFailed) {
 				contentProvider = SkeletonTreeContentProvider.INSTANCE;
 			}
 		}
 		return contentProvider;
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.ui.internal.navigator.extensions.INavigatorContentExtension#getLabelProvider()
 	 */
 	public ICommonLabelProvider getLabelProvider() {
 		if (labelProvider != null || labelProviderInitializationFailed) {
 			return labelProvider;
 		}
 		synchronized (this) {
 			try {

 				if (labelProvider == null) {
 					ILabelProvider tempLabelProvider = descriptor
 							.createLabelProvider();

 					if (tempLabelProvider instanceof ICommonLabelProvider) {
 						labelProvider = (ICommonLabelProvider) tempLabelProvider;
 							labelProvider.init(new CommonContentExtensionSite(
 									getId(), contentService, appliedMemento));
 					} else {
 						labelProvider = new SafeDelegateCommonLabelProvider(
 								tempLabelProvider);
 					}

 					labelProvider.addListener( (ILabelProviderListener)contentService.createCommonLabelProvider() );
 				}
 			} catch (CoreException e) {
 				labelProviderInitializationFailed = true;
 				e.printStackTrace();
 			} catch (RuntimeException e) {
 				labelProviderInitializationFailed = true;
 				e.printStackTrace();
 			}

 			if (labelProviderInitializationFailed) {
 				labelProvider = SkeletonLabelProvider.INSTANCE;
 			}
 		}
 		return labelProvider;
 	}

 	/**
 	 * Dispose of any resources acquired during the lifecycle of the extension.
 	 *
 	 */
 	public void dispose() {
 		try {
 			synchronized (this) {

 				SafeRunner.run(new ISafeRunnable() {

 					public void handleException(Throwable exception) {
 						String msg = exception.getMessage() != null ? exception.getMessage() : exception.toString() ;
 						NavigatorPlugin.logError(0, msg, exception);

 					}

 					public void run() throws Exception {
 						if (contentProvider != null) {
 							contentProvider.dispose();
 						}

 					}

 				});

 				SafeRunner.run(new ISafeRunnable() {

 					public void handleException(Throwable exception) {
 						String msg = exception.getMessage() != null ? exception.getMessage() : exception.toString() ;
 						NavigatorPlugin.logError(0, msg, exception);

 					}

 					public void run() throws Exception {
 						if (labelProvider != null) {
 							labelProvider.removeListener((ILabelProviderListener)contentService.createCommonLabelProvider());
 							labelProvider.dispose();
 						}

 					}

 				});

 			}
 		} finally {
 			isDisposed = true;
 		}
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.core.runtime.IAdaptable#getAdapter(java.lang.Class)
 	 */
 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.ui.internal.navigator.extensions.INavigatorContentExtension#getAdapter(java.lang.Class)
 	 */
 	public Object getAdapter(Class adapter) {
 		return null;
 	}

 	/**
 	 * @return Returns the contentProviderInitializationFailed.
 	 */
 	public boolean hasContentProviderInitializationFailed() {
 		return contentProviderInitializationFailed;
 	}

 	/**
 	 * @return Returns the labelProviderInitializationFailed.
 	 */
 	public boolean hasLabelProviderInitializationFailed() {
 		return labelProviderInitializationFailed;
 	}

 	/**
 	 *
 	 * @return True if the loading of the content provider has failed.
 	 */
 	public boolean hasLoadingFailed() {
 		return contentProviderInitializationFailed;
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.ui.internal.navigator.extensions.INavigatorContentExtension#isLoaded()
 	 */
 	public boolean isLoaded() {
 		return contentProvider != null;
 	}

 	public void restoreState(IMemento aMemento) {
 		synchronized (this) {
 			appliedMemento = aMemento;
 			applyMemento(contentProvider);
 			applyMemento(labelProvider);

 		}
 	}

 	public void saveState(IMemento aMemento) {
 		synchronized (this) {
 			if(contentProvider != null && contentProvider instanceof IMementoAware)
 				((IMementoAware)contentProvider).saveState(aMemento);
 			if(labelProvider != null && labelProvider instanceof IMementoAware)
 				((IMementoAware)labelProvider).saveState(aMemento);

 		}
 	}

 	private void applyMemento(IMementoAware target) {
 		if (target != null) {
 			target.restoreState(appliedMemento);
 		}

 	}

 	protected final void complainDisposedIfNecessary() {
 		if (isDisposed) {
 			throw new IllegalStateException("INavigatorContentExtension " //$NON-NLS-1$
 					+ descriptor.getId() + " is disposed!"); //$NON-NLS-1$
 		}
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.ui.internal.navigator.extensions.INavigatorContentExtension#getStateModel()
 	 */
 	public IExtensionStateModel getStateModel() {
 		return contentService.getExtensionStateService().getExtensionStateModel(getDescriptor());
 	}

 	/**
 	 * @param anElement
 	 *            The element for the query.
 	 * @return Returns the overridingExtensions.
 	 */
 	public NavigatorContentExtension[] getOverridingExtensionsForTriggerPoint(
 			Object anElement) {
 		if (!descriptor.hasOverridingExtensions()) {
 			return NO_EXTENSIONS;
 		}

 		NavigatorContentDescriptor overriddingDescriptor;
 		Set overridingExtensions = new LinkedHashSet();
 		for (Iterator contentDescriptorsItr = descriptor
 				.getOverriddingExtensions().iterator(); contentDescriptorsItr
 				.hasNext();) {
 			overriddingDescriptor = (NavigatorContentDescriptor) contentDescriptorsItr
 					.next();

 			if (contentService.isActive(overriddingDescriptor.getId())
 					&& contentService.isVisible(overriddingDescriptor.getId())
 					&& overriddingDescriptor.isTriggerPoint(anElement)) {
 				overridingExtensions.add(contentService
 						.getExtension(overriddingDescriptor));
 			}
 		}
 		if (overridingExtensions.size() == 0) {
 			return NO_EXTENSIONS;
 		}
 		return (NavigatorContentExtension[]) overridingExtensions
 				.toArray(new NavigatorContentExtension[overridingExtensions
 						.size()]);
 	}

 	/**
 	 *
 	 * @param anElement
 	 *            The element for the query.
 	 * @return Returns the overridingExtensions.
 	 */
 	public NavigatorContentExtension[] getOverridingExtensionsForPossibleChild(
 			Object anElement) {
 		if (!descriptor.hasOverridingExtensions()) {
 			return NO_EXTENSIONS;
 		}

 		NavigatorContentDescriptor overriddingDescriptor;
 		Set overridingExtensions = new LinkedHashSet();
 		for (Iterator contentDescriptorsItr = descriptor
 				.getOverriddingExtensions().iterator(); contentDescriptorsItr
 				.hasNext();) {
 			overriddingDescriptor = (NavigatorContentDescriptor) contentDescriptorsItr
 					.next();

 			if (contentService.isActive(overriddingDescriptor.getId())
 					&& contentService.isVisible(overriddingDescriptor.getId())
 					&& overriddingDescriptor.isPossibleChild(anElement)) {
 				overridingExtensions.add(contentService
 						.getExtension(overriddingDescriptor));
 			}
 		}
 		if (overridingExtensions.size() == 0) {
 			return NO_EXTENSIONS;
 		}
 		return (NavigatorContentExtension[]) overridingExtensions
 				.toArray(new NavigatorContentExtension[overridingExtensions
 						.size()]);
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see java.lang.Object#toString()
 	 */
 	public String toString() {
 		return descriptor.toString() + " Instance"; //$NON-NLS-1$
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2003, 2007 IBM Corporation and others.
	* All rights reserved. This program and the accompanying materials
	* are made available under the terms of the Eclipse Public License v1.0
	* which accompanies this distribution, and is available at
	* http://www.eclipse.org/legal/epl-v10.html
	*
	* Contributors:
	* IBM Corporation - initial API and implementation
	*******************************************************************************/
	package org.eclipse.ui.internal.navigator.extensions;

	import java.util.Iterator;
	import java.util.LinkedHashSet;
	import java.util.Set;

	import org.eclipse.core.runtime.Assert;
	import org.eclipse.core.runtime.CoreException;
	import org.eclipse.core.runtime.ISafeRunnable;
	import org.eclipse.core.runtime.SafeRunner;
	import org.eclipse.jface.viewers.ILabelProvider;
	import org.eclipse.jface.viewers.ILabelProviderListener;
	import org.eclipse.jface.viewers.ITreeContentProvider;
	import org.eclipse.ui.IMemento;
	import org.eclipse.ui.internal.navigator.NavigatorContentService;
	import org.eclipse.ui.internal.navigator.NavigatorPlugin;
	import org.eclipse.ui.navigator.ICommonContentProvider;
	import org.eclipse.ui.navigator.ICommonLabelProvider;
	import org.eclipse.ui.navigator.IExtensionStateModel;
	import org.eclipse.ui.navigator.IMementoAware;
	import org.eclipse.ui.navigator.INavigatorContentDescriptor;
	import org.eclipse.ui.navigator.INavigatorContentExtension;

	/**
	* <p>
	* <strong>EXPERIMENTAL</strong>. This class or interface has been added as
	* part of a work in progress. There is a guarantee neither that this API will
	* work nor that it will remain the same. Please do not use this API without
	* consulting with the Platform/UI team.
	* </p>
	*
	* @since 3.2
	*/
	public class NavigatorContentExtension implements IMementoAware,
	INavigatorContentExtension {

	private static final NavigatorContentExtension[] NO_EXTENSIONS = new NavigatorContentExtension[0];

	private NavigatorContentService contentService;

	private NavigatorContentDescriptor descriptor;

	private ICommonContentProvider contentProvider;

	private ICommonLabelProvider labelProvider;

	private boolean labelProviderInitializationFailed = false;

	private boolean contentProviderInitializationFailed = false;

	private boolean isDisposed = false;

	private IMemento appliedMemento;

	private StructuredViewerManager viewerManager;

	/**
	* Create an object to manage the instantiated elements from the extension.
	*
	* @param aDescriptor
	* The descriptor that knows how to create elements and knows the
	* id of the extension
	* @param aContentService
	* The content service that will manage this extension
	* @param aViewerManager
	* The viewer manager that knows how to initialize the content
	* provider created by this extension.
	*/
	public NavigatorContentExtension(NavigatorContentDescriptor aDescriptor,
	NavigatorContentService aContentService,
	StructuredViewerManager aViewerManager) {
	super();
	Assert.isNotNull(aDescriptor);

	descriptor = aDescriptor;
	contentService = aContentService;
	viewerManager = aViewerManager;
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.ui.internal.navigator.extensions.INavigatorContentExtension#getId()
	*/
	public String getId() {
	return descriptor.getId();
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.ui.internal.navigator.extensions.INavigatorContentExtension#getDescriptor()
	*/
	public INavigatorContentDescriptor getDescriptor() {
	return descriptor;
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.ui.navigator.INavigatorContentExtension#getContentProvider()
	*/
	public ITreeContentProvider getContentProvider() {

	ITreeContentProvider provider = internalGetContentProvider();
	if (provider != SkeletonTreeContentProvider.INSTANCE) {
	return ((SafeDelegateTreeContentProvider) provider)
	.getDelegateContentProvider();
	}
	return provider;
	}

	/**
	*
	* @return The internal content provider that is wrapped by this extension.
	*/
	public ITreeContentProvider internalGetContentProvider() {
	if (contentProvider != null \|\| contentProviderInitializationFailed) {
	return contentProvider;
	}
	synchronized (this) {
	try {
	if (contentProvider == null) {
	ITreeContentProvider treeContentProvider = descriptor
	.createContentProvider();
	if (treeContentProvider != null) {
	contentProvider = new SafeDelegateTreeContentProvider(
	treeContentProvider, descriptor, contentService);
	contentProvider.init(new CommonContentExtensionSite(
	getId(), contentService, appliedMemento));
	viewerManager.initialize(contentProvider);
	} else {
	contentProvider = SkeletonTreeContentProvider.INSTANCE;
	}
	}
	} catch (CoreException e) {
	contentProviderInitializationFailed = true;
	e.printStackTrace();
	} catch (RuntimeException e) {
	contentProviderInitializationFailed = true;
	e.printStackTrace();
	}
	if (contentProviderInitializationFailed) {
	contentProvider = SkeletonTreeContentProvider.INSTANCE;
	}
	}
	return contentProvider;
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.ui.internal.navigator.extensions.INavigatorContentExtension#getLabelProvider()
	*/
	public ICommonLabelProvider getLabelProvider() {
	if (labelProvider != null \|\| labelProviderInitializationFailed) {
	return labelProvider;
	}
	synchronized (this) {
	try {

	if (labelProvider == null) {
	ILabelProvider tempLabelProvider = descriptor
	.createLabelProvider();

	if (tempLabelProvider instanceof ICommonLabelProvider) {
	labelProvider = (ICommonLabelProvider) tempLabelProvider;
	labelProvider.init(new CommonContentExtensionSite(
	getId(), contentService, appliedMemento));
	} else {
	labelProvider = new SafeDelegateCommonLabelProvider(
	tempLabelProvider);
	}

	labelProvider.addListener( (ILabelProviderListener)contentService.createCommonLabelProvider() );
	}
	} catch (CoreException e) {
	labelProviderInitializationFailed = true;
	e.printStackTrace();
	} catch (RuntimeException e) {
	labelProviderInitializationFailed = true;
	e.printStackTrace();
	}

	if (labelProviderInitializationFailed) {
	labelProvider = SkeletonLabelProvider.INSTANCE;
	}
	}
	return labelProvider;
	}

	/**
	* Dispose of any resources acquired during the lifecycle of the extension.
	*
	*/
	public void dispose() {
	try {
	synchronized (this) {

	SafeRunner.run(new ISafeRunnable() {

	public void handleException(Throwable exception) {
	String msg = exception.getMessage() != null ? exception.getMessage() : exception.toString() ;
	NavigatorPlugin.logError(0, msg, exception);

	}

	public void run() throws Exception {
	if (contentProvider != null) {
	contentProvider.dispose();
	}

	}

	});

	SafeRunner.run(new ISafeRunnable() {

	public void handleException(Throwable exception) {
	String msg = exception.getMessage() != null ? exception.getMessage() : exception.toString() ;
	NavigatorPlugin.logError(0, msg, exception);

	}

	public void run() throws Exception {
	if (labelProvider != null) {
	labelProvider.removeListener((ILabelProviderListener)contentService.createCommonLabelProvider());
	labelProvider.dispose();
	}

	}

	});

	}
	} finally {
	isDisposed = true;
	}
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.core.runtime.IAdaptable#getAdapter(java.lang.Class)
	*/
	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.ui.internal.navigator.extensions.INavigatorContentExtension#getAdapter(java.lang.Class)
	*/
	public Object getAdapter(Class adapter) {
	return null;
	}

	/**
	* @return Returns the contentProviderInitializationFailed.
	*/
	public boolean hasContentProviderInitializationFailed() {
	return contentProviderInitializationFailed;
	}

	/**
	* @return Returns the labelProviderInitializationFailed.
	*/
	public boolean hasLabelProviderInitializationFailed() {
	return labelProviderInitializationFailed;
	}

	/**
	*
	* @return True if the loading of the content provider has failed.
	*/
	public boolean hasLoadingFailed() {
	return contentProviderInitializationFailed;
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.ui.internal.navigator.extensions.INavigatorContentExtension#isLoaded()
	*/
	public boolean isLoaded() {
	return contentProvider != null;
	}

	public void restoreState(IMemento aMemento) {
	synchronized (this) {
	appliedMemento = aMemento;
	applyMemento(contentProvider);
	applyMemento(labelProvider);

	}
	}

	public void saveState(IMemento aMemento) {
	synchronized (this) {
	if(contentProvider != null && contentProvider instanceof IMementoAware)
	((IMementoAware)contentProvider).saveState(aMemento);
	if(labelProvider != null && labelProvider instanceof IMementoAware)
	((IMementoAware)labelProvider).saveState(aMemento);

	}
	}

	private void applyMemento(IMementoAware target) {
	if (target != null) {
	target.restoreState(appliedMemento);
	}

	}

	protected final void complainDisposedIfNecessary() {
	if (isDisposed) {
	throw new IllegalStateException("INavigatorContentExtension " //$NON-NLS-1$
	+ descriptor.getId() + " is disposed!"); //$NON-NLS-1$
	}
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.ui.internal.navigator.extensions.INavigatorContentExtension#getStateModel()
	*/
	public IExtensionStateModel getStateModel() {
	return contentService.getExtensionStateService().getExtensionStateModel(getDescriptor());
	}

	/**
	* @param anElement
	* The element for the query.
	* @return Returns the overridingExtensions.
	*/
	public NavigatorContentExtension[] getOverridingExtensionsForTriggerPoint(
	Object anElement) {
	if (!descriptor.hasOverridingExtensions()) {
	return NO_EXTENSIONS;
	}

	NavigatorContentDescriptor overriddingDescriptor;
	Set overridingExtensions = new LinkedHashSet();
	for (Iterator contentDescriptorsItr = descriptor
	.getOverriddingExtensions().iterator(); contentDescriptorsItr
	.hasNext();) {
	overriddingDescriptor = (NavigatorContentDescriptor) contentDescriptorsItr
	.next();

	if (contentService.isActive(overriddingDescriptor.getId())
	&& contentService.isVisible(overriddingDescriptor.getId())
	&& overriddingDescriptor.isTriggerPoint(anElement)) {
	overridingExtensions.add(contentService
	.getExtension(overriddingDescriptor));
	}
	}
	if (overridingExtensions.size() == 0) {
	return NO_EXTENSIONS;
	}
	return (NavigatorContentExtension[]) overridingExtensions
	.toArray(new NavigatorContentExtension[overridingExtensions
	.size()]);
	}

	/**
	*
	* @param anElement
	* The element for the query.
	* @return Returns the overridingExtensions.
	*/
	public NavigatorContentExtension[] getOverridingExtensionsForPossibleChild(
	Object anElement) {
	if (!descriptor.hasOverridingExtensions()) {
	return NO_EXTENSIONS;
	}

	NavigatorContentDescriptor overriddingDescriptor;
	Set overridingExtensions = new LinkedHashSet();
	for (Iterator contentDescriptorsItr = descriptor
	.getOverriddingExtensions().iterator(); contentDescriptorsItr
	.hasNext();) {
	overriddingDescriptor = (NavigatorContentDescriptor) contentDescriptorsItr
	.next();

	if (contentService.isActive(overriddingDescriptor.getId())
	&& contentService.isVisible(overriddingDescriptor.getId())
	&& overriddingDescriptor.isPossibleChild(anElement)) {
	overridingExtensions.add(contentService
	.getExtension(overriddingDescriptor));
	}
	}
	if (overridingExtensions.size() == 0) {
	return NO_EXTENSIONS;
	}
	return (NavigatorContentExtension[]) overridingExtensions
	.toArray(new NavigatorContentExtension[overridingExtensions
	.size()]);
	}

	/*
	* (non-Javadoc)
	*
	* @see java.lang.Object#toString()
	*/
	public String toString() {
	return descriptor.toString() + " Instance"; //$NON-NLS-1$
	}
	}