org.eclipse.debug.ui/ui/org/eclipse/debug/internal/ui/model/viewers/AsynchronousModel.java - gerrit/platform/eclipse.platform.debug - Git at Google

 /*******************************************************************************
  * Copyright (c) 2006 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.debug.internal.ui.model.viewers;

 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;

 import org.eclipse.core.runtime.IAdaptable;
 import org.eclipse.debug.internal.ui.elements.adapters.AsynchronousDebugLabelAdapter;
 import org.eclipse.debug.internal.ui.viewers.provisional.IAsynchronousContentAdapter;
 import org.eclipse.debug.internal.ui.viewers.provisional.IAsynchronousLabelAdapter;
 import org.eclipse.debug.internal.ui.viewers.provisional.IAsynchronousRequestMonitor;
 import org.eclipse.debug.internal.ui.viewers.provisional.IChildrenRequestMonitor;
 import org.eclipse.debug.internal.ui.viewers.provisional.ILabelRequestMonitor;
 import org.eclipse.debug.internal.ui.viewers.provisional.IModelProxy;
 import org.eclipse.debug.internal.ui.viewers.provisional.IModelProxyFactoryAdapter;
 import org.eclipse.debug.internal.ui.viewers.provisional.IPresentationContext;
 import org.eclipse.jface.viewers.ViewerFilter;
 import org.eclipse.jface.viewers.ViewerSorter;
 import org.eclipse.swt.widgets.Widget;

 /**
  * Model for an asynchronous viewer
  *
  * @since 3.2
  */
 public abstract class AsynchronousModel {

 	private ModelNode fRoot; // root node
 	private Map fWidgetToNode = new HashMap(); // map of widgets to corresponding tree node
 	private Map fElementToNodes = new HashMap(); // map of element to corresponding tree nodes (list)
 	private Map fModelProxies = new HashMap(); // map of installed model proxies, by element
 	private AsynchronousModelViewer fViewer; // viewer this model works for
     private boolean fDisposed = false; // whether disposed

 	/**
 	 * List of requests currently being performed.
 	 */
 	private List fPendingUpdates = new ArrayList();

 	/**
 	 * List of pending viewer udpates
 	 */
 	private List fViewerUpdates = new ArrayList();

 	/**
 	 * Constructs a new empty tree model
 	 *
 	 * @param viewer associated viewer
 	 * @param root root element or <code>null</code>
 	 */
 	public AsynchronousModel(AsynchronousModelViewer viewer, Object root, Widget widget) {
 		fViewer = viewer;
 		if (root != null) {
 			fRoot = new ModelNode(null, root);
 			fRoot.setWidget(widget);
 			mapWidget(widget, fRoot);
 			mapElement(root, fRoot);
 		}
 	}

 	protected AsynchronousModelViewer getViewer() {
 		return fViewer;
 	}

 	/**
 	 * Disposes this model
 	 */
 	public synchronized void dispose() {
         fDisposed = true;
         cancelPendingUpdates();
 		disposeAllModelProxies();
 		fPendingUpdates.clear();
 	}

     /**
      * Returns whether this model has been disposed
      */
     public synchronized boolean isDisposed() {
         return fDisposed;
     }

     /**
      * Cancels all pending update requests.
      */
     protected synchronized void cancelPendingUpdates() {
         Iterator updates = fPendingUpdates.iterator();
         while (updates.hasNext()) {
             IAsynchronousRequestMonitor update = (IAsynchronousRequestMonitor) updates.next();
             updates.remove();
             update.setCanceled(true);
         }
         fPendingUpdates.clear();
     }

 	/**
 	 * Installs the model proxy for the given element into this viewer
 	 * if not already installed.
 	 *
 	 * @param element element to install an update policy for
 	 */
 	public synchronized void installModelProxy(Object element) {
 		if (!fModelProxies.containsKey(element)) {
 			IModelProxyFactoryAdapter modelProxyFactory = getModelProxyFactoryAdapter(element);
 			if (modelProxyFactory != null) {
 				IModelProxy proxy = modelProxyFactory.createModelProxy(element, getPresentationContext());
 				if (proxy != null) {
 					proxy.init(getPresentationContext());
 					fModelProxies.put(element, proxy);
 					getViewer().modelProxyAdded(proxy);
 					proxy.installed();
 				}
 			}
 		}
 	}

 	/**
 	 * Uninstalls the model proxy installed for the given element, if any.
 	 *
 	 * @param element
 	 */
 	protected synchronized void disposeModelProxy(Object element) {
 		IModelProxy proxy = (IModelProxy) fModelProxies.remove(element);
 		if (proxy != null) {
 			getViewer().modelProxyRemoved(proxy);
 			proxy.dispose();
 		}
 	}

 	/**
 	 * Unintalls all model proxies installed for this model
 	 */
 	private void disposeAllModelProxies() {
 	    synchronized(fModelProxies) {
 	        Iterator updatePolicies = fModelProxies.values().iterator();
 	        while (updatePolicies.hasNext()) {
 	            IModelProxy proxy = (IModelProxy)updatePolicies.next();
 	            getViewer().modelProxyRemoved(proxy);
 	            proxy.dispose();
 	        }

 	        fModelProxies.clear();
 	    }
 	}

 	/**
 	 * Returns the presentation this model is installed in
 	 *
 	 * @return
 	 */
 	protected IPresentationContext getPresentationContext() {
 		return fViewer.getPresentationContext();
 	}

 	/**
 	 * Returns the model proxy factory for the given element of <code>null</code> if none.
 	 *
 	 * @param element element to retrieve adapters for
 	 * @return model proxy factory adapter or <code>null</code>
 	 */
 	protected IModelProxyFactoryAdapter getModelProxyFactoryAdapter(Object element) {
 		IModelProxyFactoryAdapter adapter = null;
 		if (element instanceof IModelProxyFactoryAdapter) {
 			adapter = (IModelProxyFactoryAdapter) element;
 		} else if (element instanceof IAdaptable) {
 			IAdaptable adaptable = (IAdaptable) element;
 			adapter = (IModelProxyFactoryAdapter) adaptable.getAdapter(IModelProxyFactoryAdapter.class);
 		}
 		return adapter;
 	}

 	/**
 	 * Maps the given widget to the given node
 	 *
 	 * @param widget
 	 * @param node
 	 */
 	protected void mapWidget(Widget widget, ModelNode node) {
 		Object element = node.getElement();
 		widget.setData(element);
         node.setWidget(widget);
 		fWidgetToNode.put(widget, node);
 	}

 	/**
 	 * Maps the given element to the given node.
 	 *
 	 * @param element
 	 * @param node
 	 */
 	protected synchronized void mapElement(Object element, ModelNode node) {
 		ModelNode[] nodes = getNodes(element);
         node.remap(element);
 		if (nodes == null) {
 			fElementToNodes.put(element, new ModelNode[] { node});
 		} else {
 			for (int i = 0; i < nodes.length; i++) {
 				if (nodes[i] == node) {
 					return;
 				}
 			}
 			ModelNode[] old = nodes;
 			ModelNode[] newNodes = new ModelNode[old.length + 1];
 			System.arraycopy(old, 0, newNodes, 0, old.length);
 			newNodes[old.length] = node;
 			fElementToNodes.put(element, newNodes);
 		}
         installModelProxy(element);
 	}

     /**
      * Unmaps the given node from its element and widget.
      *
      * @param node
      */
     protected synchronized void unmapNode(ModelNode node) {
         Object element = node.getElement();
         ModelNode[] nodes = (ModelNode[]) fElementToNodes.get(element);
         if (nodes == null) {
             return;
         }
         if (nodes.length == 1) {
             fElementToNodes.remove(element);
             disposeModelProxy(element);
         } else {
             for (int i = 0; i < nodes.length; i++) {
                 ModelNode node2 = nodes[i];
                 if (node2 == node) {
                     ModelNode[] newNodes= new ModelNode[nodes.length - 1];
                     System.arraycopy(nodes, 0, newNodes, 0, i);
                     if (i < newNodes.length) {
                         System.arraycopy(nodes, i + 1, newNodes, i, newNodes.length - i);
                     }
                     fElementToNodes.put(element, newNodes);
                 }
             }
         }
     }

 	/**
 	 * Returns the nodes in this model for the given element or
      * <code>null</code> if none.
 	 *
 	 * @param element model element
 	 * @return associated nodes or <code>null</code>
 	 */
 	protected ModelNode[] getNodes(Object element) {
 		return (ModelNode[]) fElementToNodes.get(element);
 	}

 	/**
 	 * Returns the node mapped to the given widet, or <code>null</code>
 	 *
 	 * @param widget
 	 * @return
 	 */
 	protected ModelNode getNode(Widget widget) {
 		return (ModelNode) fWidgetToNode.get(widget);
 	}

 	/**
 	 * Returns the root node or <code>null</code>
 	 *
 	 * @return the root node or <code>null</code>
 	 */
 	protected ModelNode getRootNode() {
 		return fRoot;
 	}

 	/**
 	 * Cancels any conflicting updates for children of the given item, and
 	 * schedules the new update.
 	 *
 	 * @param update the update to schedule
 	 */
 	protected void requestScheduled(IAsynchronousRequestMonitor update) {
 		AsynchronousModelRequestMonitor absUpdate = (AsynchronousModelRequestMonitor) update;
 		synchronized (fPendingUpdates) {
 			Iterator updates = fPendingUpdates.listIterator();
 			while (updates.hasNext()) {
 				AsynchronousModelRequestMonitor pendingUpdate = (AsynchronousModelRequestMonitor) updates.next();
 				if (absUpdate.contains(pendingUpdate)) {
 					updates.remove();
 					pendingUpdate.setCanceled(true);
 				}
 			}
 			fPendingUpdates.add(update);
 		}
 	}

 	/**
 	 * Removes the update from the pending updates list.
 	 *
 	 * @param update
 	 */
 	protected void requestComplete(IAsynchronousRequestMonitor update) {
 		synchronized (fPendingUpdates) {
 			fPendingUpdates.remove(update);
 		}
 	}

 	/**
 	 * An viewer update has been scheduled due to the following update request.
 	 *
 	 * @param update
 	 */
 	protected void viewerUpdateScheduled(IAsynchronousRequestMonitor update) {
 		synchronized (fViewerUpdates) {
 			fViewerUpdates.add(update);
 		}
 	}

 	/**
 	 * Returns the result of running the given elements through the
 	 * viewers filters.
 	 *
 	 * @param parent parent element
 	 * @param elements the elements to filter
 	 * @return only the elements which all filters accept
 	 */
 	protected Object[] filter(Object parent, Object[] elements) {
 		ViewerFilter[] filters = getViewer().getFilters();
 		if (filters != null) {
 			ArrayList filtered = new ArrayList(elements.length);
 			for (int i = 0; i < elements.length; i++) {
 				boolean add = true;
 				for (int j = 0; j < filters.length; j++) {
 					add = filters[j].select(getViewer(), parent, elements[i]);
 					if (!add)
 						break;
 				}
 				if (add)
 					filtered.add(elements[i]);
 			}
 			return filtered.toArray();
 		}
 		return elements;
 	}

 	/**
 	 * Returns the model node the given widget is mapped to or <code>null</code>
 	 *
 	 * @param widget
 	 * @return
 	 */
 	public ModelNode getModelNode(Widget widget) {
 		return (ModelNode) fWidgetToNode.get(widget);
 	}

 	/**
 	 * Refreshes the given node.
 	 *
 	 * @param node
 	 */
 	protected void updateLabel(ModelNode node) {
 		Object element = node.getElement();
 		IAsynchronousLabelAdapter adapter = getLabelAdapter(element);
 		if (adapter != null) {
 			ILabelRequestMonitor labelUpdate = new ModelLabelRequestMonitor(node, this);
 			requestScheduled(labelUpdate);
 			adapter.retrieveLabel(element, getPresentationContext(), labelUpdate);
 		}
 	}

 	/**
 	 * Returns the label adapter for the given element or <code>null</code> if none.
 	 *
 	 * @param element element to retrieve adapter for
 	 * @return presentation adapter or <code>null</code>
 	 */
 	protected IAsynchronousLabelAdapter getLabelAdapter(Object element) {
 		IAsynchronousLabelAdapter adapter = null;
 		if (element instanceof IAsynchronousLabelAdapter) {
 			adapter = (IAsynchronousLabelAdapter) element;
 		} else if (element instanceof IAdaptable) {
 			IAdaptable adaptable = (IAdaptable) element;
 			adapter = (IAsynchronousLabelAdapter) adaptable.getAdapter(IAsynchronousLabelAdapter.class);
 		}
 		// if no adapter, use default (i.e. model presentation)
 		if (adapter == null) {
 			return new AsynchronousDebugLabelAdapter();
 		}
 		return adapter;
 	}

     /**
      * Returns the tree element adapter for the given element or
      * <code>null</code> if none.
      *
      * @param element
      *            element to retrieve adapter for
      * @return presentation adapter or <code>null</code>
      */
     protected IAsynchronousContentAdapter getContentAdapter(Object element) {
         IAsynchronousContentAdapter adapter = null;
         if (element instanceof IAsynchronousContentAdapter) {
             adapter = (IAsynchronousContentAdapter) element;
         } else if (element instanceof IAdaptable) {
             IAdaptable adaptable = (IAdaptable) element;
             adapter = (IAsynchronousContentAdapter) adaptable.getAdapter(IAsynchronousContentAdapter.class);
         }
         return adapter;
     }

     /**
      * Updates the children of the given node.
      *
      * @param parent
      *            node of which to update children
      */
     protected void updateChildren(ModelNode parent) {
         Object element = parent.getElement();
         IAsynchronousContentAdapter adapter = getContentAdapter(element);
         if (adapter != null) {
             IChildrenRequestMonitor update = new ModelChildrenRequestMonitor(parent, this);
             requestScheduled(update);
             adapter.retrieveChildren(element, getPresentationContext(), update);
         }
     }

 	/**
 	 * Update this model's viewer preserving its selection.
 	 *
 	 * @param update
 	 */
 	protected void preservingSelection(Runnable update) {
 		getViewer().preservingSelection(update);
 	}

 	/**
 	 * The viewer updated associated with a request is compelte.
 	 *
 	 * @param monitor
 	 */
 	protected void viewerUpdateComplete(IAsynchronousRequestMonitor monitor) {
 		synchronized (fViewerUpdates) {
 			fViewerUpdates.remove(monitor);
 		}
 		getViewer().updateComplete(monitor);
 	}

 	/**
 	 * An update request was cancelled
 	 *
 	 * @param monitor
 	 */
 	protected void requestCanceled(AsynchronousModelRequestMonitor monitor) {
 		synchronized (fPendingUpdates) {
 			fPendingUpdates.remove(monitor);
 		}
 	}

 	/**
 	 * Whether any updates are still in progress in the model or against the viewer.
 	 *
 	 * @return
 	 */
 	protected boolean hasPendingUpdates() {
 		synchronized (fViewerUpdates) {
 			return !fPendingUpdates.isEmpty() || !fViewerUpdates.isEmpty();
 		}
 	}

     /**
      * Asynchronous update for add/set children request.
      *
      * @param parent
      * @param element
      */
 	protected abstract void add(ModelNode parent, Object element);

 	/**
 	 * Notification from children request monitor
 	 *
 	 * @param parentNode parent node
 	 * @param kids list of model elements
 	 */
 	protected void setChildren(final ModelNode parentNode, List kids) {

         final Object[] children = filter(parentNode.getElement(), kids.toArray());
         final AsynchronousModelViewer viewer = getViewer();
         ViewerSorter sorter = viewer.getSorter();
         if (sorter != null) {
         	sorter.sort(viewer, children);
         }

         final ModelNode[] prevKids = parentNode.getChildrenNodes();
         if (prevKids == null) {
         	final ModelNode[] newKids = new ModelNode[children.length];
             synchronized (this) {
                 if (isDisposed()) {
                     return;
                 }
             	for (int i = 0; i < children.length; i++) {
     				ModelNode node = new ModelNode(parentNode, children[i]);
     				mapElement(children[i], node);
     				newKids[i] = node;
     			}
             	parentNode.setChildren(newKids);
             }
             preservingSelection(new Runnable() {
                 public void run() {
 //                  the tree could have asked for data before it was ready...
                     viewer.nodeChildrenSet(parentNode, newKids);
                 }
             });

         } else {
             synchronized (this) {
                 if (isDisposed()) {
                     return;
                 }
     	        for (int i = 0; i < prevKids.length; i++) {
     				ModelNode kid = prevKids[i];
     				if (i >= children.length) {
     					kid.dispose();
     					unmapNode(kid);
     				} else {
     					ModelNode prevNode = prevKids[i];
     					Object nextChild = children[i];
     					if (!prevNode.getElement().equals(nextChild)) {
     						unmapNode(prevNode);
     					}
     					mapElement(nextChild, prevNode);
     				}
     			}
     			// create new children
     	        if (children.length > prevKids.length) {
     		        ModelNode[] replaceChildren = new ModelNode[children.length];
     		        System.arraycopy(prevKids, 0, replaceChildren, 0, prevKids.length);
     		        for (int i = prevKids.length; i < children.length; i ++) {
     		        	Object child = children[i];
     					ModelNode childNode = new ModelNode(parentNode, child);
     		        	mapElement(child, childNode);
     		        	replaceChildren[i] = childNode;
     		        }
     		        parentNode.setChildren(replaceChildren);
     	        }
                 if (children.length < prevKids.length) {
                     ModelNode[] replaceChildren = new ModelNode[children.length];
                     System.arraycopy(prevKids, 0, replaceChildren, 0, children.length);
                     parentNode.setChildren(replaceChildren);
                 }

             }
             // update viewer outside the lock

             preservingSelection(new Runnable() {
                 public void run() {
                     for (int i = 0; i < prevKids.length; i++) {
                         ModelNode kid = prevKids[i];
                         if (i >= children.length) {
                             viewer.nodeDisposed(kid);
                         } else {
                             viewer.nodeChanged(kid);
                         }
                     }
                     viewer.nodeChildrenChanged(parentNode);
                 }
             });

         }
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2006 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.debug.internal.ui.model.viewers;

	import java.util.ArrayList;
	import java.util.HashMap;
	import java.util.Iterator;
	import java.util.List;
	import java.util.Map;

	import org.eclipse.core.runtime.IAdaptable;
	import org.eclipse.debug.internal.ui.elements.adapters.AsynchronousDebugLabelAdapter;
	import org.eclipse.debug.internal.ui.viewers.provisional.IAsynchronousContentAdapter;
	import org.eclipse.debug.internal.ui.viewers.provisional.IAsynchronousLabelAdapter;
	import org.eclipse.debug.internal.ui.viewers.provisional.IAsynchronousRequestMonitor;
	import org.eclipse.debug.internal.ui.viewers.provisional.IChildrenRequestMonitor;
	import org.eclipse.debug.internal.ui.viewers.provisional.ILabelRequestMonitor;
	import org.eclipse.debug.internal.ui.viewers.provisional.IModelProxy;
	import org.eclipse.debug.internal.ui.viewers.provisional.IModelProxyFactoryAdapter;
	import org.eclipse.debug.internal.ui.viewers.provisional.IPresentationContext;
	import org.eclipse.jface.viewers.ViewerFilter;
	import org.eclipse.jface.viewers.ViewerSorter;
	import org.eclipse.swt.widgets.Widget;

	/**
	* Model for an asynchronous viewer
	*
	* @since 3.2
	*/
	public abstract class AsynchronousModel {

	private ModelNode fRoot; // root node
	private Map fWidgetToNode = new HashMap(); // map of widgets to corresponding tree node
	private Map fElementToNodes = new HashMap(); // map of element to corresponding tree nodes (list)
	private Map fModelProxies = new HashMap(); // map of installed model proxies, by element
	private AsynchronousModelViewer fViewer; // viewer this model works for
	private boolean fDisposed = false; // whether disposed

	/**
	* List of requests currently being performed.
	*/
	private List fPendingUpdates = new ArrayList();

	/**
	* List of pending viewer udpates
	*/
	private List fViewerUpdates = new ArrayList();

	/**
	* Constructs a new empty tree model
	*
	* @param viewer associated viewer
	* @param root root element or <code>null</code>
	*/
	public AsynchronousModel(AsynchronousModelViewer viewer, Object root, Widget widget) {
	fViewer = viewer;
	if (root != null) {
	fRoot = new ModelNode(null, root);
	fRoot.setWidget(widget);
	mapWidget(widget, fRoot);
	mapElement(root, fRoot);
	}
	}

	protected AsynchronousModelViewer getViewer() {
	return fViewer;
	}

	/**
	* Disposes this model
	*/
	public synchronized void dispose() {
	fDisposed = true;
	cancelPendingUpdates();
	disposeAllModelProxies();
	fPendingUpdates.clear();
	}

	/**
	* Returns whether this model has been disposed
	*/
	public synchronized boolean isDisposed() {
	return fDisposed;
	}

	/**
	* Cancels all pending update requests.
	*/
	protected synchronized void cancelPendingUpdates() {
	Iterator updates = fPendingUpdates.iterator();
	while (updates.hasNext()) {
	IAsynchronousRequestMonitor update = (IAsynchronousRequestMonitor) updates.next();
	updates.remove();
	update.setCanceled(true);
	}
	fPendingUpdates.clear();
	}

	/**
	* Installs the model proxy for the given element into this viewer
	* if not already installed.
	*
	* @param element element to install an update policy for
	*/
	public synchronized void installModelProxy(Object element) {
	if (!fModelProxies.containsKey(element)) {
	IModelProxyFactoryAdapter modelProxyFactory = getModelProxyFactoryAdapter(element);
	if (modelProxyFactory != null) {
	IModelProxy proxy = modelProxyFactory.createModelProxy(element, getPresentationContext());
	if (proxy != null) {
	proxy.init(getPresentationContext());
	fModelProxies.put(element, proxy);
	getViewer().modelProxyAdded(proxy);
	proxy.installed();
	}
	}
	}
	}

	/**
	* Uninstalls the model proxy installed for the given element, if any.
	*
	* @param element
	*/
	protected synchronized void disposeModelProxy(Object element) {
	IModelProxy proxy = (IModelProxy) fModelProxies.remove(element);
	if (proxy != null) {
	getViewer().modelProxyRemoved(proxy);
	proxy.dispose();
	}
	}

	/**
	* Unintalls all model proxies installed for this model
	*/
	private void disposeAllModelProxies() {
	synchronized(fModelProxies) {
	Iterator updatePolicies = fModelProxies.values().iterator();
	while (updatePolicies.hasNext()) {
	IModelProxy proxy = (IModelProxy)updatePolicies.next();
	getViewer().modelProxyRemoved(proxy);
	proxy.dispose();
	}

	fModelProxies.clear();
	}
	}

	/**
	* Returns the presentation this model is installed in
	*
	* @return
	*/
	protected IPresentationContext getPresentationContext() {
	return fViewer.getPresentationContext();
	}

	/**
	* Returns the model proxy factory for the given element of <code>null</code> if none.
	*
	* @param element element to retrieve adapters for
	* @return model proxy factory adapter or <code>null</code>
	*/
	protected IModelProxyFactoryAdapter getModelProxyFactoryAdapter(Object element) {
	IModelProxyFactoryAdapter adapter = null;
	if (element instanceof IModelProxyFactoryAdapter) {
	adapter = (IModelProxyFactoryAdapter) element;
	} else if (element instanceof IAdaptable) {
	IAdaptable adaptable = (IAdaptable) element;
	adapter = (IModelProxyFactoryAdapter) adaptable.getAdapter(IModelProxyFactoryAdapter.class);
	}
	return adapter;
	}

	/**
	* Maps the given widget to the given node
	*
	* @param widget
	* @param node
	*/
	protected void mapWidget(Widget widget, ModelNode node) {
	Object element = node.getElement();
	widget.setData(element);
	node.setWidget(widget);
	fWidgetToNode.put(widget, node);
	}

	/**
	* Maps the given element to the given node.
	*
	* @param element
	* @param node
	*/
	protected synchronized void mapElement(Object element, ModelNode node) {
	ModelNode[] nodes = getNodes(element);
	node.remap(element);
	if (nodes == null) {
	fElementToNodes.put(element, new ModelNode[] { node});
	} else {
	for (int i = 0; i < nodes.length; i++) {
	if (nodes[i] == node) {
	return;
	}
	}
	ModelNode[] old = nodes;
	ModelNode[] newNodes = new ModelNode[old.length + 1];
	System.arraycopy(old, 0, newNodes, 0, old.length);
	newNodes[old.length] = node;
	fElementToNodes.put(element, newNodes);
	}
	installModelProxy(element);
	}

	/**
	* Unmaps the given node from its element and widget.
	*
	* @param node
	*/
	protected synchronized void unmapNode(ModelNode node) {
	Object element = node.getElement();
	ModelNode[] nodes = (ModelNode[]) fElementToNodes.get(element);
	if (nodes == null) {
	return;
	}
	if (nodes.length == 1) {
	fElementToNodes.remove(element);
	disposeModelProxy(element);
	} else {
	for (int i = 0; i < nodes.length; i++) {
	ModelNode node2 = nodes[i];
	if (node2 == node) {
	ModelNode[] newNodes= new ModelNode[nodes.length - 1];
	System.arraycopy(nodes, 0, newNodes, 0, i);
	if (i < newNodes.length) {
	System.arraycopy(nodes, i + 1, newNodes, i, newNodes.length - i);
	}
	fElementToNodes.put(element, newNodes);
	}
	}
	}
	}

	/**
	* Returns the nodes in this model for the given element or
	* <code>null</code> if none.
	*
	* @param element model element
	* @return associated nodes or <code>null</code>
	*/
	protected ModelNode[] getNodes(Object element) {
	return (ModelNode[]) fElementToNodes.get(element);
	}

	/**
	* Returns the node mapped to the given widet, or <code>null</code>
	*
	* @param widget
	* @return
	*/
	protected ModelNode getNode(Widget widget) {
	return (ModelNode) fWidgetToNode.get(widget);
	}

	/**
	* Returns the root node or <code>null</code>
	*
	* @return the root node or <code>null</code>
	*/
	protected ModelNode getRootNode() {
	return fRoot;
	}

	/**
	* Cancels any conflicting updates for children of the given item, and
	* schedules the new update.
	*
	* @param update the update to schedule
	*/
	protected void requestScheduled(IAsynchronousRequestMonitor update) {
	AsynchronousModelRequestMonitor absUpdate = (AsynchronousModelRequestMonitor) update;
	synchronized (fPendingUpdates) {
	Iterator updates = fPendingUpdates.listIterator();
	while (updates.hasNext()) {
	AsynchronousModelRequestMonitor pendingUpdate = (AsynchronousModelRequestMonitor) updates.next();
	if (absUpdate.contains(pendingUpdate)) {
	updates.remove();
	pendingUpdate.setCanceled(true);
	}
	}
	fPendingUpdates.add(update);
	}
	}

	/**
	* Removes the update from the pending updates list.
	*
	* @param update
	*/
	protected void requestComplete(IAsynchronousRequestMonitor update) {
	synchronized (fPendingUpdates) {
	fPendingUpdates.remove(update);
	}
	}

	/**
	* An viewer update has been scheduled due to the following update request.
	*
	* @param update
	*/
	protected void viewerUpdateScheduled(IAsynchronousRequestMonitor update) {
	synchronized (fViewerUpdates) {
	fViewerUpdates.add(update);
	}
	}

	/**
	* Returns the result of running the given elements through the
	* viewers filters.
	*
	* @param parent parent element
	* @param elements the elements to filter
	* @return only the elements which all filters accept
	*/
	protected Object[] filter(Object parent, Object[] elements) {
	ViewerFilter[] filters = getViewer().getFilters();
	if (filters != null) {
	ArrayList filtered = new ArrayList(elements.length);
	for (int i = 0; i < elements.length; i++) {
	boolean add = true;
	for (int j = 0; j < filters.length; j++) {
	add = filters[j].select(getViewer(), parent, elements[i]);
	if (!add)
	break;
	}
	if (add)
	filtered.add(elements[i]);
	}
	return filtered.toArray();
	}
	return elements;
	}

	/**
	* Returns the model node the given widget is mapped to or <code>null</code>
	*
	* @param widget
	* @return
	*/
	public ModelNode getModelNode(Widget widget) {
	return (ModelNode) fWidgetToNode.get(widget);
	}

	/**
	* Refreshes the given node.
	*
	* @param node
	*/
	protected void updateLabel(ModelNode node) {
	Object element = node.getElement();
	IAsynchronousLabelAdapter adapter = getLabelAdapter(element);
	if (adapter != null) {
	ILabelRequestMonitor labelUpdate = new ModelLabelRequestMonitor(node, this);
	requestScheduled(labelUpdate);
	adapter.retrieveLabel(element, getPresentationContext(), labelUpdate);
	}
	}

	/**
	* Returns the label adapter for the given element or <code>null</code> if none.
	*
	* @param element element to retrieve adapter for
	* @return presentation adapter or <code>null</code>
	*/
	protected IAsynchronousLabelAdapter getLabelAdapter(Object element) {
	IAsynchronousLabelAdapter adapter = null;
	if (element instanceof IAsynchronousLabelAdapter) {
	adapter = (IAsynchronousLabelAdapter) element;
	} else if (element instanceof IAdaptable) {
	IAdaptable adaptable = (IAdaptable) element;
	adapter = (IAsynchronousLabelAdapter) adaptable.getAdapter(IAsynchronousLabelAdapter.class);
	}
	// if no adapter, use default (i.e. model presentation)
	if (adapter == null) {
	return new AsynchronousDebugLabelAdapter();
	}
	return adapter;
	}

	/**
	* Returns the tree element adapter for the given element or
	* <code>null</code> if none.
	*
	* @param element
	* element to retrieve adapter for
	* @return presentation adapter or <code>null</code>
	*/
	protected IAsynchronousContentAdapter getContentAdapter(Object element) {
	IAsynchronousContentAdapter adapter = null;
	if (element instanceof IAsynchronousContentAdapter) {
	adapter = (IAsynchronousContentAdapter) element;
	} else if (element instanceof IAdaptable) {
	IAdaptable adaptable = (IAdaptable) element;
	adapter = (IAsynchronousContentAdapter) adaptable.getAdapter(IAsynchronousContentAdapter.class);
	}
	return adapter;
	}

	/**
	* Updates the children of the given node.
	*
	* @param parent
	* node of which to update children
	*/
	protected void updateChildren(ModelNode parent) {
	Object element = parent.getElement();
	IAsynchronousContentAdapter adapter = getContentAdapter(element);
	if (adapter != null) {
	IChildrenRequestMonitor update = new ModelChildrenRequestMonitor(parent, this);
	requestScheduled(update);
	adapter.retrieveChildren(element, getPresentationContext(), update);
	}
	}

	/**
	* Update this model's viewer preserving its selection.
	*
	* @param update
	*/
	protected void preservingSelection(Runnable update) {
	getViewer().preservingSelection(update);
	}

	/**
	* The viewer updated associated with a request is compelte.
	*
	* @param monitor
	*/
	protected void viewerUpdateComplete(IAsynchronousRequestMonitor monitor) {
	synchronized (fViewerUpdates) {
	fViewerUpdates.remove(monitor);
	}
	getViewer().updateComplete(monitor);
	}

	/**
	* An update request was cancelled
	*
	* @param monitor
	*/
	protected void requestCanceled(AsynchronousModelRequestMonitor monitor) {
	synchronized (fPendingUpdates) {
	fPendingUpdates.remove(monitor);
	}
	}

	/**
	* Whether any updates are still in progress in the model or against the viewer.
	*
	* @return
	*/
	protected boolean hasPendingUpdates() {
	synchronized (fViewerUpdates) {
	return !fPendingUpdates.isEmpty() \|\| !fViewerUpdates.isEmpty();
	}
	}

	/**
	* Asynchronous update for add/set children request.
	*
	* @param parent
	* @param element
	*/
	protected abstract void add(ModelNode parent, Object element);

	/**
	* Notification from children request monitor
	*
	* @param parentNode parent node
	* @param kids list of model elements
	*/
	protected void setChildren(final ModelNode parentNode, List kids) {

	final Object[] children = filter(parentNode.getElement(), kids.toArray());
	final AsynchronousModelViewer viewer = getViewer();
	ViewerSorter sorter = viewer.getSorter();
	if (sorter != null) {
	sorter.sort(viewer, children);
	}

	final ModelNode[] prevKids = parentNode.getChildrenNodes();
	if (prevKids == null) {
	final ModelNode[] newKids = new ModelNode[children.length];
	synchronized (this) {
	if (isDisposed()) {
	return;
	}
	for (int i = 0; i < children.length; i++) {
	ModelNode node = new ModelNode(parentNode, children[i]);
	mapElement(children[i], node);
	newKids[i] = node;
	}
	parentNode.setChildren(newKids);
	}
	preservingSelection(new Runnable() {
	public void run() {
	// the tree could have asked for data before it was ready...
	viewer.nodeChildrenSet(parentNode, newKids);
	}
	});

	} else {
	synchronized (this) {
	if (isDisposed()) {
	return;
	}
	for (int i = 0; i < prevKids.length; i++) {
	ModelNode kid = prevKids[i];
	if (i >= children.length) {
	kid.dispose();
	unmapNode(kid);
	} else {
	ModelNode prevNode = prevKids[i];
	Object nextChild = children[i];
	if (!prevNode.getElement().equals(nextChild)) {
	unmapNode(prevNode);
	}
	mapElement(nextChild, prevNode);
	}
	}
	// create new children
	if (children.length > prevKids.length) {
	ModelNode[] replaceChildren = new ModelNode[children.length];
	System.arraycopy(prevKids, 0, replaceChildren, 0, prevKids.length);
	for (int i = prevKids.length; i < children.length; i ++) {
	Object child = children[i];
	ModelNode childNode = new ModelNode(parentNode, child);
	mapElement(child, childNode);
	replaceChildren[i] = childNode;
	}
	parentNode.setChildren(replaceChildren);
	}
	if (children.length < prevKids.length) {
	ModelNode[] replaceChildren = new ModelNode[children.length];
	System.arraycopy(prevKids, 0, replaceChildren, 0, children.length);
	parentNode.setChildren(replaceChildren);
	}

	}
	// update viewer outside the lock

	preservingSelection(new Runnable() {
	public void run() {
	for (int i = 0; i < prevKids.length; i++) {
	ModelNode kid = prevKids[i];
	if (i >= children.length) {
	viewer.nodeDisposed(kid);
	} else {
	viewer.nodeChanged(kid);
	}
	}
	viewer.nodeChildrenChanged(parentNode);
	}
	});

	}
	}
	}