org.eclipse.gmf.runtime.diagram.ui/src/org/eclipse/gmf/runtime/diagram/ui/editpolicies/CreationEditPolicy.java - gmf-runtime/org.eclipse.gmf-runtime - Git at Google

 /******************************************************************************
  * Copyright (c) 2004, 2009 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.gmf.runtime.diagram.ui.editpolicies;

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

 import org.eclipse.core.commands.ExecutionException;
 import org.eclipse.core.resources.IFile;
 import org.eclipse.core.runtime.Assert;
 import org.eclipse.core.runtime.IAdaptable;
 import org.eclipse.core.runtime.IProgressMonitor;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;
 import org.eclipse.emf.ecore.EObject;
 import org.eclipse.emf.transaction.TransactionalEditingDomain;
 import org.eclipse.gef.EditPart;
 import org.eclipse.gef.Request;
 import org.eclipse.gef.commands.Command;
 import org.eclipse.gef.commands.UnexecutableCommand;
 import org.eclipse.gef.editpolicies.AbstractEditPolicy;
 import org.eclipse.gef.requests.ChangeBoundsRequest;
 import org.eclipse.gef.requests.CreateRequest;
 import org.eclipse.gmf.runtime.common.core.command.CommandResult;
 import org.eclipse.gmf.runtime.common.core.command.CompositeCommand;
 import org.eclipse.gmf.runtime.common.core.command.FileModificationValidator;
 import org.eclipse.gmf.runtime.common.core.command.ICommand;
 import org.eclipse.gmf.runtime.diagram.core.commands.AddCommand;
 import org.eclipse.gmf.runtime.diagram.core.edithelpers.CreateElementRequestAdapter;
 import org.eclipse.gmf.runtime.diagram.core.util.ViewUtil;
 import org.eclipse.gmf.runtime.diagram.ui.commands.CommandProxy;
 import org.eclipse.gmf.runtime.diagram.ui.commands.CommandUtilities;
 import org.eclipse.gmf.runtime.diagram.ui.commands.CreateCommand;
 import org.eclipse.gmf.runtime.diagram.ui.commands.CreateOrSelectElementCommand;
 import org.eclipse.gmf.runtime.diagram.ui.commands.ICommandProxy;
 import org.eclipse.gmf.runtime.diagram.ui.commands.SemanticCreateCommand;
 import org.eclipse.gmf.runtime.diagram.ui.editparts.GroupEditPart;
 import org.eclipse.gmf.runtime.diagram.ui.editparts.IGraphicalEditPart;
 import org.eclipse.gmf.runtime.diagram.ui.editparts.LabelEditPart;
 import org.eclipse.gmf.runtime.diagram.ui.l10n.DiagramUIMessages;
 import org.eclipse.gmf.runtime.diagram.ui.requests.CreateUnspecifiedTypeRequest;
 import org.eclipse.gmf.runtime.diagram.ui.requests.CreateViewAndElementRequest;
 import org.eclipse.gmf.runtime.diagram.ui.requests.CreateViewRequest;
 import org.eclipse.gmf.runtime.diagram.ui.requests.EditCommandRequestWrapper;
 import org.eclipse.gmf.runtime.diagram.ui.requests.RefreshConnectionsRequest;
 import org.eclipse.gmf.runtime.diagram.ui.requests.RequestConstants;
 import org.eclipse.gmf.runtime.emf.commands.core.command.CompositeTransactionalCommand;
 import org.eclipse.gmf.runtime.emf.core.util.EObjectAdapter;
 import org.eclipse.gmf.runtime.emf.type.core.IElementType;
 import org.eclipse.gmf.runtime.emf.type.core.requests.CreateElementRequest;
 import org.eclipse.gmf.runtime.emf.type.core.requests.MoveRequest;
 import org.eclipse.gmf.runtime.notation.View;
 import org.eclipse.swt.widgets.Display;

 /**
  * This edit policy returns the command that will create a new notational view
  * for a the given request.
  *
  * @author choang
  */
 public class CreationEditPolicy extends AbstractEditPolicy {

 	/**
 	 * @return Command for the REQ_CREATE request. If the request is of type
 	 *         CreateViewAndElementRequest then a command to create the
 	 *         semantic, and the view will
 	 * @see org.eclipse.gef.EditPolicy#getCommand(org.eclipse.gef.Request)
 	 */
 	public Command getCommand(Request request) {
 		if (understandsRequest(request)) {
 			if (request instanceof CreateUnspecifiedTypeRequest) {
 				return getUnspecifiedTypeCreateCommand((CreateUnspecifiedTypeRequest) request);
 			} else if (request instanceof CreateViewAndElementRequest) {
 				return getCreateElementAndViewCommand(
 					(CreateViewAndElementRequest)request);
 			}
 			else if (request instanceof CreateViewRequest) {
 				return getCreateCommand((CreateViewRequest)request);
 			}
 			else if (request instanceof ChangeBoundsRequest) {
 				return getReparentCommand((ChangeBoundsRequest)request);
 			}
 			return super.getCommand(request);
 		}
 		return null;
 	}

 	/** Understands <tt>REQ_CREATE</tt> and <tt>REQ_ADD</tt> request types. */
 	public boolean understandsRequest(Request request) {
 		return RequestConstants.REQ_CREATE.equals(request.getType())
 		    || RequestConstants.REQ_ADD.equals(request.getType())
 			|| super.understandsRequest(request);
 	}

 	/**
 	 * Determines if a semantic reparent is being performed.
 	 * @param element element being reparented
 	 * @param newContext the new container element
 	 * @return <tt>true</tt> if the supplied elemnet's container is
 	 * not equals to the supplied <code>newContext</code>.\; otherwise <tt>false</tt>.
 	 */
 	protected boolean shouldReparent( EObject element, EObject newContext ) {
 		return !(element == null ||
 				element == newContext ||
 				element.eContainer() == newContext ||
 				isContainedIn( element, newContext )
 				);
 	}

 	/*
 	 * This method checks to see element's containment tree already includes
 	 * itself.  This is necessary to prevent cyclic graphs in the model that
 	 * cause StackOverflowExceptions.
 	 */
 	private boolean isContainedIn( EObject element, EObject newContext )
 	{
 		EObject container = newContext.eContainer();
 		while( container != null ) {
 			if( container.equals(element) )
 				return true;
 			container = container.eContainer();
 		}
 		return false;
 	}

 	/** Return a command to reparent both the semantic and view elements. */
 	/**
 	 * return a command to reparent both the semantic and view elements.
 	 * @param request the request
 	 * @return command
 	 */
 	protected Command getReparentCommand(ChangeBoundsRequest request) {
 		Iterator editParts = request.getEditParts().iterator();
 		View container = (View)getHost().getAdapter(View.class);
 		EObject context = container == null ? null : ViewUtil.resolveSemanticElement(container);
         CompositeCommand cc = new CompositeCommand(DiagramUIMessages.AddCommand_Label);
 		while ( editParts.hasNext() ) {
 			EditPart ep = (EditPart)editParts.next();
 			if ( ep instanceof LabelEditPart ) {
 				continue;
 			}
 			if (ep instanceof GroupEditPart) {
                 cc.compose(getReparentGroupCommand((GroupEditPart) ep));
             }
 			View view = (View)ep.getAdapter(View.class);
 			if ( view == null ) {
 				continue;
 			}

 			EObject semantic = ViewUtil.resolveSemanticElement(view);
 			if ( semantic == null ) {
 				cc.compose(getReparentViewCommand((IGraphicalEditPart)ep));
 			}
 			else if ( context != null && shouldReparent(semantic, context)) {
 				cc.compose(getReparentCommand((IGraphicalEditPart)ep));
 			}
 		}
 		return cc.isEmpty() ? null : new ICommandProxy(cc.reduce());
 	}

     /**
      * Return the command to reparent the supplied group editpart's semantic and
      * notation elements.
      *
      * @param gep
      *            the groupEP editpart being reparented
      * @return A composite command that will reparent both the semantic and
      *         notation elements of the group.
      */
     protected ICommand getReparentGroupCommand(GroupEditPart groupEP) {
         CompositeCommand cc = new CompositeCommand(
             DiagramUIMessages.AddCommand_Label);
         View container = (View) getHost().getModel();
         EObject context = ViewUtil.resolveSemanticElement(container);

         // semantic
         TransactionalEditingDomain editingDomain = ((IGraphicalEditPart) getHost())
             .getEditingDomain();
         for (Iterator iter = groupEP.getShapeChildren().iterator(); iter
             .hasNext();) {
             IGraphicalEditPart childEP = (IGraphicalEditPart) iter.next();
             EObject element = ViewUtil.resolveSemanticElement((View) childEP
                 .getModel());
             if (element != null) {
                 Command moveSemanticCmd = getHost().getCommand(
                     new EditCommandRequestWrapper(new MoveRequest(
                         editingDomain, context, element)));

                 if (moveSemanticCmd == null) {
                     return org.eclipse.gmf.runtime.common.core.command.UnexecutableCommand.INSTANCE;
                 }

                 cc.compose(new CommandProxy(moveSemanticCmd));
             }
         }

         // notation
         cc.compose(getReparentViewCommand(groupEP));
         return cc;
     }

 	/**
 	 * Return the command to reparent the supplied editpart's semantic and notation
 	 * elements.
 	 * @param gep the editpart being reparented
 	 * @return A CompositeCommand2 that will reparent both the semantic and notation elements.
 	 */
 	protected ICommand getReparentCommand( IGraphicalEditPart gep ) {
         CompositeCommand cc = new CompositeCommand(DiagramUIMessages.AddCommand_Label);
 		View container = (View)getHost().getModel();
 		EObject context = ViewUtil.resolveSemanticElement(container);
 		View view = (View)gep.getModel();
 		EObject element = ViewUtil.resolveSemanticElement(view);

         TransactionalEditingDomain editingDomain = ((IGraphicalEditPart) getHost())
             .getEditingDomain();

         //
 		// semantic
 		if ( element != null ) {
 			Command moveSemanticCmd =
 				getHost().getCommand(
 					new EditCommandRequestWrapper(
 						new MoveRequest(editingDomain, context, element)));

               if (moveSemanticCmd == null) {
                   return org.eclipse.gmf.runtime.common.core.command.UnexecutableCommand.INSTANCE;
               }

 			cc.compose ( new CommandProxy(moveSemanticCmd) );
 		}
 		//
 		// notation
 		cc.compose(getReparentViewCommand(gep));
 		return cc;
 	}

 	/**
 	 * Return the command to reparent the supplied editpart's view only.
 	 * @param gep the editpart being reparented
 	 * @return A command to reparent the notation element.
 	 */
 	protected ICommand getReparentViewCommand( IGraphicalEditPart gep ) {
 		View container = (View)getHost().getModel();
 		View view = (View)gep.getModel();
 		return new AddCommand(gep.getEditingDomain(), new EObjectAdapter(container),
 							  new EObjectAdapter(view));
 	}

 	/**
 	 * Called in response to a <tt>REQ_CREATE</tt> request.
 	 *
 	 * Creates a compound command and populated with the following commands for
 	 * each element to be created: <BR>
 	 * <OL>
 	 * <LI>a {@link CreateCommand}for each of the request's view descriptor.
 	 * </OL>
 	 *
 	 * @param request
 	 *            a create request (understands instances of
 	 *            {@link CreateViewRequest}).
 	 * @return a command to satify the request; <tt>null</tt> if the request
 	 *         is not understood.
 	 */
 	protected Command getCreateCommand(CreateViewRequest request) {

         TransactionalEditingDomain editingDomain = ((IGraphicalEditPart) getHost())
             .getEditingDomain();
         CompositeTransactionalCommand cc = new CompositeTransactionalCommand(
             editingDomain, DiagramUIMessages.AddCommand_Label);

         Iterator descriptors = request.getViewDescriptors().iterator();

 		while (descriptors.hasNext()) {
 			CreateViewRequest.ViewDescriptor descriptor =
 				(CreateViewRequest.ViewDescriptor)descriptors.next();

 			CreateCommand createCommand =
 				new CreateCommand(editingDomain,
 					descriptor,
 					(View)(getHost().getModel()));

 			cc.compose(createCommand);
 		}
 		return new ICommandProxy(cc.reduce());

 	}

 	/**
 	 * Method getCreateElementAndViewCommand.
 	 *
 	 * @param request
 	 * @return Command Which creates the sematnic and the view command for the
 	 *         given CreateViewAndElementRequest
 	 */
 	protected Command getCreateElementAndViewCommand(CreateViewAndElementRequest request) {
 		// get the element descriptor
 		CreateElementRequestAdapter requestAdapter =
 			request.getViewAndElementDescriptor().getCreateElementRequestAdapter();

 		// get the semantic request
 		CreateElementRequest createElementRequest =
 			(CreateElementRequest) requestAdapter.getAdapter(
 				CreateElementRequest.class);

 		if (createElementRequest.getContainer() == null) {
 			// complete the semantic request by filling in the host's semantic
 			// element as the context
 			View view = (View)getHost().getModel();
 			EObject hostElement = ViewUtil.resolveSemanticElement(view);

 			if (hostElement == null && view.getElement() == null) {
 				hostElement = view;
 			}

 			// Returns null if host is unresolvable so that trying to create a
 			// new element in an unresolved shape will not be allowed.
 			if (hostElement == null) {
 				return null;
 			}
 			createElementRequest.setContainer(hostElement);
 		}

 		// get the create element command based on the elementdescriptor's
 		// request
 		Command createElementCommand =
 			getHost().getCommand(
 				new EditCommandRequestWrapper(
 					(CreateElementRequest)requestAdapter.getAdapter(
 						CreateElementRequest.class), request.getExtendedData()));

 		if (createElementCommand == null) {
 			return UnexecutableCommand.INSTANCE;
 		}
 		if(!createElementCommand.canExecute()){
 			return createElementCommand;
 		}
 		// create the semantic create wrapper command
 		SemanticCreateCommand semanticCommand =
 			new SemanticCreateCommand(requestAdapter, createElementCommand);
 		Command viewCommand = getCreateCommand(request);

 		Command refreshConnectionCommand =
 			getHost().getCommand(
 				new RefreshConnectionsRequest(((List)request.getNewObject())));


 		// form the compound command and return
         CompositeCommand cc = new CompositeCommand(semanticCommand.getLabel());
 		cc.compose(semanticCommand);
 		cc.compose(new CommandProxy(viewCommand));
 		if ( refreshConnectionCommand != null ) {
 			cc.compose(new CommandProxy(refreshConnectionCommand));
 		}

 		return new ICommandProxy(cc);
 	}

 	/**
 	 * Gets the command to create a new view (and optionally element) for an
 	 * unspecified type request. This command includes a command to popup a menu
 	 * to prompt the user for the type to be created.
 	 *
 	 * @param request
 	 *            the unspecified type request
 	 * @return the command
 	 */
 	private Command getUnspecifiedTypeCreateCommand(
 			final CreateUnspecifiedTypeRequest request) {

 		final Map createCmds = new HashMap();
 		List validTypes = new ArrayList();
 		for (Iterator iter = request.getElementTypes().iterator(); iter
 			.hasNext();) {
 			IElementType elementType = (IElementType) iter.next();
 			Request createRequest = request.getRequestForType(elementType);
 			if (createRequest != null) {
 				EditPart target = getHost().getTargetEditPart(createRequest);
 				if ( target == null )  {
 					continue;
 				}
 				Command individualCmd = target.getCommand(createRequest);

 				if (individualCmd != null && individualCmd.canExecute()) {
 					createCmds.put(elementType, individualCmd);
 					validTypes.add(elementType);
 				}
 			}
 		}

 		if (createCmds.isEmpty()) {
 			return null;
 		} else if (createCmds.size() == 1) {
 			return (Command) createCmds.values().toArray()[0];
 		} else {
 			CreateOrSelectElementCommand selectAndCreateViewCmd = new CreateOrSelectElementCommand(
                 DiagramUIMessages.CreateCommand_Label, Display.getCurrent()
                     .getActiveShell(), validTypes) {

 				private Command _createCmd;
 				/**
 				 * Execute the command that prompts the user with the popup
 				 * menu, then executes the command prepared for the element
 				 * type that the user selected.
 				 */
 				protected CommandResult doExecuteWithResult(
                         IProgressMonitor progressMonitor, IAdaptable info)
                     throws ExecutionException {

 					CommandResult cmdResult = super.doExecuteWithResult(progressMonitor, info);
 					if (!cmdResult.getStatus().isOK()) {
 						return cmdResult;
 					}

 					IElementType type = (IElementType) cmdResult
 						.getReturnValue();

 					_createCmd = (Command) createCmds.get(type);
 					Assert.isTrue(_createCmd != null && _createCmd.canExecute());

 					// validate the affected files
 					IStatus status = validateAffectedFiles(_createCmd);
 					if (!status.isOK()) {
 						return new CommandResult(status);
 					}

 					_createCmd.execute();

 					// Set the result in the unspecified type request.
 					CreateRequest createRequest = request
 						.getRequestForType(type);

                     Collection newObject = ((Collection) createRequest
                             .getNewObject());
 					request.setNewObject(newObject);

 					return CommandResult.newOKCommandResult(newObject);
 				}

 				protected CommandResult doUndoWithResult(
                         IProgressMonitor progressMonitor, IAdaptable info)
                     throws ExecutionException {

 					if (_createCmd != null && _createCmd.canUndo() ) {
 						// validate the affected files
 						IStatus status = validateAffectedFiles(_createCmd);
 						if (!status.isOK()) {
 							return new CommandResult(status);
 						}
 						_createCmd.undo();
 					}
 					return super.doUndoWithResult(progressMonitor, info);
 				}

 				protected CommandResult doRedoWithResult(
                         IProgressMonitor progressMonitor, IAdaptable info)
                     throws ExecutionException {

 					if (_createCmd != null && CommandUtilities.canRedo(_createCmd)) {
 						// validate the affected files
 						IStatus status = validateAffectedFiles(_createCmd);
 						if (!status.isOK()) {
 							return new CommandResult(status);
 						}
 						_createCmd.redo();
 					}
 					return super.doRedoWithResult(progressMonitor, info);
 				}

 				private IStatus validateAffectedFiles(Command command) {
 					Collection affectedFiles = CommandUtilities
 							.getAffectedFiles(command);
 					int fileCount = affectedFiles.size();
 					if (fileCount > 0) {
 						return FileModificationValidator
 								.approveFileModification((IFile[]) affectedFiles
 										.toArray(new IFile[fileCount]));
 					}
 					return Status.OK_STATUS;
 				}
 			};

 			return new ICommandProxy(selectAndCreateViewCmd);
 		}
 	}

 	/** Return the host if this editpolicy understands the supplied request. */
 	public EditPart getTargetEditPart(Request request) {
 		return understandsRequest(request) ? getHost() : null;
 	}
 }
	/******************************************************************************
	* Copyright (c) 2004, 2009 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.gmf.runtime.diagram.ui.editpolicies;

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

	import org.eclipse.core.commands.ExecutionException;
	import org.eclipse.core.resources.IFile;
	import org.eclipse.core.runtime.Assert;
	import org.eclipse.core.runtime.IAdaptable;
	import org.eclipse.core.runtime.IProgressMonitor;
	import org.eclipse.core.runtime.IStatus;
	import org.eclipse.core.runtime.Status;
	import org.eclipse.emf.ecore.EObject;
	import org.eclipse.emf.transaction.TransactionalEditingDomain;
	import org.eclipse.gef.EditPart;
	import org.eclipse.gef.Request;
	import org.eclipse.gef.commands.Command;
	import org.eclipse.gef.commands.UnexecutableCommand;
	import org.eclipse.gef.editpolicies.AbstractEditPolicy;
	import org.eclipse.gef.requests.ChangeBoundsRequest;
	import org.eclipse.gef.requests.CreateRequest;
	import org.eclipse.gmf.runtime.common.core.command.CommandResult;
	import org.eclipse.gmf.runtime.common.core.command.CompositeCommand;
	import org.eclipse.gmf.runtime.common.core.command.FileModificationValidator;
	import org.eclipse.gmf.runtime.common.core.command.ICommand;
	import org.eclipse.gmf.runtime.diagram.core.commands.AddCommand;
	import org.eclipse.gmf.runtime.diagram.core.edithelpers.CreateElementRequestAdapter;
	import org.eclipse.gmf.runtime.diagram.core.util.ViewUtil;
	import org.eclipse.gmf.runtime.diagram.ui.commands.CommandProxy;
	import org.eclipse.gmf.runtime.diagram.ui.commands.CommandUtilities;
	import org.eclipse.gmf.runtime.diagram.ui.commands.CreateCommand;
	import org.eclipse.gmf.runtime.diagram.ui.commands.CreateOrSelectElementCommand;
	import org.eclipse.gmf.runtime.diagram.ui.commands.ICommandProxy;
	import org.eclipse.gmf.runtime.diagram.ui.commands.SemanticCreateCommand;
	import org.eclipse.gmf.runtime.diagram.ui.editparts.GroupEditPart;
	import org.eclipse.gmf.runtime.diagram.ui.editparts.IGraphicalEditPart;
	import org.eclipse.gmf.runtime.diagram.ui.editparts.LabelEditPart;
	import org.eclipse.gmf.runtime.diagram.ui.l10n.DiagramUIMessages;
	import org.eclipse.gmf.runtime.diagram.ui.requests.CreateUnspecifiedTypeRequest;
	import org.eclipse.gmf.runtime.diagram.ui.requests.CreateViewAndElementRequest;
	import org.eclipse.gmf.runtime.diagram.ui.requests.CreateViewRequest;
	import org.eclipse.gmf.runtime.diagram.ui.requests.EditCommandRequestWrapper;
	import org.eclipse.gmf.runtime.diagram.ui.requests.RefreshConnectionsRequest;
	import org.eclipse.gmf.runtime.diagram.ui.requests.RequestConstants;
	import org.eclipse.gmf.runtime.emf.commands.core.command.CompositeTransactionalCommand;
	import org.eclipse.gmf.runtime.emf.core.util.EObjectAdapter;
	import org.eclipse.gmf.runtime.emf.type.core.IElementType;
	import org.eclipse.gmf.runtime.emf.type.core.requests.CreateElementRequest;
	import org.eclipse.gmf.runtime.emf.type.core.requests.MoveRequest;
	import org.eclipse.gmf.runtime.notation.View;
	import org.eclipse.swt.widgets.Display;

	/**
	* This edit policy returns the command that will create a new notational view
	* for a the given request.
	*
	* @author choang
	*/
	public class CreationEditPolicy extends AbstractEditPolicy {

	/**
	* @return Command for the REQ_CREATE request. If the request is of type
	* CreateViewAndElementRequest then a command to create the
	* semantic, and the view will
	* @see org.eclipse.gef.EditPolicy#getCommand(org.eclipse.gef.Request)
	*/
	public Command getCommand(Request request) {
	if (understandsRequest(request)) {
	if (request instanceof CreateUnspecifiedTypeRequest) {
	return getUnspecifiedTypeCreateCommand((CreateUnspecifiedTypeRequest) request);
	} else if (request instanceof CreateViewAndElementRequest) {
	return getCreateElementAndViewCommand(
	(CreateViewAndElementRequest)request);
	}
	else if (request instanceof CreateViewRequest) {
	return getCreateCommand((CreateViewRequest)request);
	}
	else if (request instanceof ChangeBoundsRequest) {
	return getReparentCommand((ChangeBoundsRequest)request);
	}
	return super.getCommand(request);
	}
	return null;
	}

	/** Understands <tt>REQ_CREATE</tt> and <tt>REQ_ADD</tt> request types. */
	public boolean understandsRequest(Request request) {
	return RequestConstants.REQ_CREATE.equals(request.getType())
	\|\| RequestConstants.REQ_ADD.equals(request.getType())
	\|\| super.understandsRequest(request);
	}

	/**
	* Determines if a semantic reparent is being performed.
	* @param element element being reparented
	* @param newContext the new container element
	* @return <tt>true</tt> if the supplied elemnet's container is
	* not equals to the supplied <code>newContext</code>.\; otherwise <tt>false</tt>.
	*/
	protected boolean shouldReparent( EObject element, EObject newContext ) {
	return !(element == null \|\|
	element == newContext \|\|
	element.eContainer() == newContext \|\|
	isContainedIn( element, newContext )
	);
	}

	/*
	* This method checks to see element's containment tree already includes
	* itself. This is necessary to prevent cyclic graphs in the model that
	* cause StackOverflowExceptions.
	*/
	private boolean isContainedIn( EObject element, EObject newContext )
	{
	EObject container = newContext.eContainer();
	while( container != null ) {
	if( container.equals(element) )
	return true;
	container = container.eContainer();
	}
	return false;
	}

	/** Return a command to reparent both the semantic and view elements. */
	/**
	* return a command to reparent both the semantic and view elements.
	* @param request the request
	* @return command
	*/
	protected Command getReparentCommand(ChangeBoundsRequest request) {
	Iterator editParts = request.getEditParts().iterator();
	View container = (View)getHost().getAdapter(View.class);
	EObject context = container == null ? null : ViewUtil.resolveSemanticElement(container);
	CompositeCommand cc = new CompositeCommand(DiagramUIMessages.AddCommand_Label);
	while ( editParts.hasNext() ) {
	EditPart ep = (EditPart)editParts.next();
	if ( ep instanceof LabelEditPart ) {
	continue;
	}
	if (ep instanceof GroupEditPart) {
	cc.compose(getReparentGroupCommand((GroupEditPart) ep));
	}
	View view = (View)ep.getAdapter(View.class);
	if ( view == null ) {
	continue;
	}

	EObject semantic = ViewUtil.resolveSemanticElement(view);
	if ( semantic == null ) {
	cc.compose(getReparentViewCommand((IGraphicalEditPart)ep));
	}
	else if ( context != null && shouldReparent(semantic, context)) {
	cc.compose(getReparentCommand((IGraphicalEditPart)ep));
	}
	}
	return cc.isEmpty() ? null : new ICommandProxy(cc.reduce());
	}

	/**
	* Return the command to reparent the supplied group editpart's semantic and
	* notation elements.
	*
	* @param gep
	* the groupEP editpart being reparented
	* @return A composite command that will reparent both the semantic and
	* notation elements of the group.
	*/
	protected ICommand getReparentGroupCommand(GroupEditPart groupEP) {
	CompositeCommand cc = new CompositeCommand(
	DiagramUIMessages.AddCommand_Label);
	View container = (View) getHost().getModel();
	EObject context = ViewUtil.resolveSemanticElement(container);

	// semantic
	TransactionalEditingDomain editingDomain = ((IGraphicalEditPart) getHost())
	.getEditingDomain();
	for (Iterator iter = groupEP.getShapeChildren().iterator(); iter
	.hasNext();) {
	IGraphicalEditPart childEP = (IGraphicalEditPart) iter.next();
	EObject element = ViewUtil.resolveSemanticElement((View) childEP
	.getModel());
	if (element != null) {
	Command moveSemanticCmd = getHost().getCommand(
	new EditCommandRequestWrapper(new MoveRequest(
	editingDomain, context, element)));

	if (moveSemanticCmd == null) {
	return org.eclipse.gmf.runtime.common.core.command.UnexecutableCommand.INSTANCE;
	}

	cc.compose(new CommandProxy(moveSemanticCmd));
	}
	}

	// notation
	cc.compose(getReparentViewCommand(groupEP));
	return cc;
	}

	/**
	* Return the command to reparent the supplied editpart's semantic and notation
	* elements.
	* @param gep the editpart being reparented
	* @return A CompositeCommand2 that will reparent both the semantic and notation elements.
	*/
	protected ICommand getReparentCommand( IGraphicalEditPart gep ) {
	CompositeCommand cc = new CompositeCommand(DiagramUIMessages.AddCommand_Label);
	View container = (View)getHost().getModel();
	EObject context = ViewUtil.resolveSemanticElement(container);
	View view = (View)gep.getModel();
	EObject element = ViewUtil.resolveSemanticElement(view);

	TransactionalEditingDomain editingDomain = ((IGraphicalEditPart) getHost())
	.getEditingDomain();

	//
	// semantic
	if ( element != null ) {
	Command moveSemanticCmd =
	getHost().getCommand(
	new EditCommandRequestWrapper(
	new MoveRequest(editingDomain, context, element)));

	if (moveSemanticCmd == null) {
	return org.eclipse.gmf.runtime.common.core.command.UnexecutableCommand.INSTANCE;
	}

	cc.compose ( new CommandProxy(moveSemanticCmd) );
	}
	//
	// notation
	cc.compose(getReparentViewCommand(gep));
	return cc;
	}

	/**
	* Return the command to reparent the supplied editpart's view only.
	* @param gep the editpart being reparented
	* @return A command to reparent the notation element.
	*/
	protected ICommand getReparentViewCommand( IGraphicalEditPart gep ) {
	View container = (View)getHost().getModel();
	View view = (View)gep.getModel();
	return new AddCommand(gep.getEditingDomain(), new EObjectAdapter(container),
	new EObjectAdapter(view));
	}

	/**
	* Called in response to a <tt>REQ_CREATE</tt> request.
	*
	* Creates a compound command and populated with the following commands for
	* each element to be created: <BR>
	* <OL>
	* <LI>a {@link CreateCommand}for each of the request's view descriptor.
	* </OL>
	*
	* @param request
	* a create request (understands instances of
	* {@link CreateViewRequest}).
	* @return a command to satify the request; <tt>null</tt> if the request
	* is not understood.
	*/
	protected Command getCreateCommand(CreateViewRequest request) {

	TransactionalEditingDomain editingDomain = ((IGraphicalEditPart) getHost())
	.getEditingDomain();
	CompositeTransactionalCommand cc = new CompositeTransactionalCommand(
	editingDomain, DiagramUIMessages.AddCommand_Label);

	Iterator descriptors = request.getViewDescriptors().iterator();

	while (descriptors.hasNext()) {
	CreateViewRequest.ViewDescriptor descriptor =
	(CreateViewRequest.ViewDescriptor)descriptors.next();

	CreateCommand createCommand =
	new CreateCommand(editingDomain,
	descriptor,
	(View)(getHost().getModel()));

	cc.compose(createCommand);
	}
	return new ICommandProxy(cc.reduce());

	}

	/**
	* Method getCreateElementAndViewCommand.
	*
	* @param request
	* @return Command Which creates the sematnic and the view command for the
	* given CreateViewAndElementRequest
	*/
	protected Command getCreateElementAndViewCommand(CreateViewAndElementRequest request) {
	// get the element descriptor
	CreateElementRequestAdapter requestAdapter =
	request.getViewAndElementDescriptor().getCreateElementRequestAdapter();

	// get the semantic request
	CreateElementRequest createElementRequest =
	(CreateElementRequest) requestAdapter.getAdapter(
	CreateElementRequest.class);

	if (createElementRequest.getContainer() == null) {
	// complete the semantic request by filling in the host's semantic
	// element as the context
	View view = (View)getHost().getModel();
	EObject hostElement = ViewUtil.resolveSemanticElement(view);

	if (hostElement == null && view.getElement() == null) {
	hostElement = view;
	}

	// Returns null if host is unresolvable so that trying to create a
	// new element in an unresolved shape will not be allowed.
	if (hostElement == null) {
	return null;
	}
	createElementRequest.setContainer(hostElement);
	}

	// get the create element command based on the elementdescriptor's
	// request
	Command createElementCommand =
	getHost().getCommand(
	new EditCommandRequestWrapper(
	(CreateElementRequest)requestAdapter.getAdapter(
	CreateElementRequest.class), request.getExtendedData()));

	if (createElementCommand == null) {
	return UnexecutableCommand.INSTANCE;
	}
	if(!createElementCommand.canExecute()){
	return createElementCommand;
	}
	// create the semantic create wrapper command
	SemanticCreateCommand semanticCommand =
	new SemanticCreateCommand(requestAdapter, createElementCommand);
	Command viewCommand = getCreateCommand(request);

	Command refreshConnectionCommand =
	getHost().getCommand(
	new RefreshConnectionsRequest(((List)request.getNewObject())));


	// form the compound command and return
	CompositeCommand cc = new CompositeCommand(semanticCommand.getLabel());
	cc.compose(semanticCommand);
	cc.compose(new CommandProxy(viewCommand));
	if ( refreshConnectionCommand != null ) {
	cc.compose(new CommandProxy(refreshConnectionCommand));
	}

	return new ICommandProxy(cc);
	}

	/**
	* Gets the command to create a new view (and optionally element) for an
	* unspecified type request. This command includes a command to popup a menu
	* to prompt the user for the type to be created.
	*
	* @param request
	* the unspecified type request
	* @return the command
	*/
	private Command getUnspecifiedTypeCreateCommand(
	final CreateUnspecifiedTypeRequest request) {

	final Map createCmds = new HashMap();
	List validTypes = new ArrayList();
	for (Iterator iter = request.getElementTypes().iterator(); iter
	.hasNext();) {
	IElementType elementType = (IElementType) iter.next();
	Request createRequest = request.getRequestForType(elementType);
	if (createRequest != null) {
	EditPart target = getHost().getTargetEditPart(createRequest);
	if ( target == null ) {
	continue;
	}
	Command individualCmd = target.getCommand(createRequest);

	if (individualCmd != null && individualCmd.canExecute()) {
	createCmds.put(elementType, individualCmd);
	validTypes.add(elementType);
	}
	}
	}

	if (createCmds.isEmpty()) {
	return null;
	} else if (createCmds.size() == 1) {
	return (Command) createCmds.values().toArray()[0];
	} else {
	CreateOrSelectElementCommand selectAndCreateViewCmd = new CreateOrSelectElementCommand(
	DiagramUIMessages.CreateCommand_Label, Display.getCurrent()
	.getActiveShell(), validTypes) {

	private Command _createCmd;
	/**
	* Execute the command that prompts the user with the popup
	* menu, then executes the command prepared for the element
	* type that the user selected.
	*/
	protected CommandResult doExecuteWithResult(
	IProgressMonitor progressMonitor, IAdaptable info)
	throws ExecutionException {

	CommandResult cmdResult = super.doExecuteWithResult(progressMonitor, info);
	if (!cmdResult.getStatus().isOK()) {
	return cmdResult;
	}

	IElementType type = (IElementType) cmdResult
	.getReturnValue();

	_createCmd = (Command) createCmds.get(type);
	Assert.isTrue(_createCmd != null && _createCmd.canExecute());

	// validate the affected files
	IStatus status = validateAffectedFiles(_createCmd);
	if (!status.isOK()) {
	return new CommandResult(status);
	}

	_createCmd.execute();

	// Set the result in the unspecified type request.
	CreateRequest createRequest = request
	.getRequestForType(type);

	Collection newObject = ((Collection) createRequest
	.getNewObject());
	request.setNewObject(newObject);

	return CommandResult.newOKCommandResult(newObject);
	}

	protected CommandResult doUndoWithResult(
	IProgressMonitor progressMonitor, IAdaptable info)
	throws ExecutionException {

	if (_createCmd != null && _createCmd.canUndo() ) {
	// validate the affected files
	IStatus status = validateAffectedFiles(_createCmd);
	if (!status.isOK()) {
	return new CommandResult(status);
	}
	_createCmd.undo();
	}
	return super.doUndoWithResult(progressMonitor, info);
	}

	protected CommandResult doRedoWithResult(
	IProgressMonitor progressMonitor, IAdaptable info)
	throws ExecutionException {

	if (_createCmd != null && CommandUtilities.canRedo(_createCmd)) {
	// validate the affected files
	IStatus status = validateAffectedFiles(_createCmd);
	if (!status.isOK()) {
	return new CommandResult(status);
	}
	_createCmd.redo();
	}
	return super.doRedoWithResult(progressMonitor, info);
	}

	private IStatus validateAffectedFiles(Command command) {
	Collection affectedFiles = CommandUtilities
	.getAffectedFiles(command);
	int fileCount = affectedFiles.size();
	if (fileCount > 0) {
	return FileModificationValidator
	.approveFileModification((IFile[]) affectedFiles
	.toArray(new IFile[fileCount]));
	}
	return Status.OK_STATUS;
	}
	};

	return new ICommandProxy(selectAndCreateViewCmd);
	}
	}

	/** Return the host if this editpolicy understands the supplied request. */
	public EditPart getTargetEditPart(Request request) {
	return understandsRequest(request) ? getHost() : null;
	}
	}