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

 /******************************************************************************
  * Copyright (c) 2002, 2008 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.List;

 import org.eclipse.emf.ecore.EObject;
 import org.eclipse.emf.edit.domain.IEditingDomainProvider;
 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.CompoundCommand;
 import org.eclipse.gef.commands.UnexecutableCommand;
 import org.eclipse.gef.requests.GroupRequest;
 import org.eclipse.gmf.runtime.common.core.command.CompositeCommand;
 import org.eclipse.gmf.runtime.common.core.util.StringStatics;
 import org.eclipse.gmf.runtime.diagram.core.commands.DeleteCommand;
 import org.eclipse.gmf.runtime.diagram.core.util.ViewUtil;
 import org.eclipse.gmf.runtime.diagram.ui.commands.ICommandProxy;
 import org.eclipse.gmf.runtime.diagram.ui.editparts.GraphicalEditPart;
 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.IInsertableEditPart;
 import org.eclipse.gmf.runtime.diagram.ui.editparts.SemanticListCompartmentEditPart;
 import org.eclipse.gmf.runtime.diagram.ui.l10n.DiagramUIMessages;
 import org.eclipse.gmf.runtime.diagram.ui.preferences.IPreferenceConstants;
 import org.eclipse.gmf.runtime.diagram.ui.requests.EditCommandRequestWrapper;
 import org.eclipse.gmf.runtime.diagram.ui.requests.GroupRequestViaKeyboard;
 import org.eclipse.gmf.runtime.diagram.ui.requests.RequestConstants;
 import org.eclipse.gmf.runtime.emf.type.core.requests.CreateElementRequest;
 import org.eclipse.gmf.runtime.emf.type.core.requests.DestroyElementRequest;
 import org.eclipse.gmf.runtime.notation.View;
 import org.eclipse.jface.dialogs.IDialogConstants;
 import org.eclipse.jface.dialogs.MessageDialogWithToggle;
 import org.eclipse.jface.preference.IPreferenceStore;
 import org.eclipse.swt.widgets.Display;

 /**
  * Concrete class that extends the GEF's <code>ComponentEditPolicy</code>.
  * This edit policy will return a command in response to delete requests.
  *
  * @author Vishy Ramaswamy
  */
 public class ComponentEditPolicy
 	extends org.eclipse.gef.editpolicies.ComponentEditPolicy {

 	private static final String DELETE_FROM_DIAGRAM_DLG_TITLE = DiagramUIMessages.PromptingDeleteAction_DeleteFromDiagramDialog_Title;

 	private static final String DELETE_FROM_DIAGRAM_DLG_MESSAGE = DiagramUIMessages.PromptingDeleteAction_DeleteFromDiagramDialog_Message;

 	private static final String DELETE_FROM_MODEL_DLG_TOGGLE_LABEL = DiagramUIMessages.MessageDialogWithToggle_DoNotPromptAgainToggle_label;


 	/**
 	 * Returns a delete command to honour the supplied request.
 	 * Calls {@link #createDeleteSemanticCommand(GroupRequest)} if
 	 * {@link #shouldDeleteSemantic()} returns <tt>true</tt>; othwerise
 	 * {@link #createDeleteViewCommand(GroupRequest)} is called.
 	 * @see org.eclipse.gef.editpolicies.ComponentEditPolicy#createDeleteCommand(GroupRequest)
 	 */
 	protected final Command createDeleteCommand(GroupRequest deleteRequest) {

 		if (shouldDeleteSemantic()){
 			return createDeleteSemanticCommand(deleteRequest);
 		}
 		if (deleteRequest instanceof GroupRequestViaKeyboard) {
 			boolean shouldShowPrompt = ((GroupRequestViaKeyboard) deleteRequest)
 				.isShowInformationDialog();
 			if (shouldShowPrompt) {
 				((GroupRequestViaKeyboard) deleteRequest)
 					.setShowInformationDialog(false);
 				if (showPrompt() == false) {
 					return UnexecutableCommand.INSTANCE;
 				}
 			}
 		}
 		return createDeleteViewCommand(deleteRequest);

 	}

 	/**
 	 * Return <tt>true</tt> if the host element should delete its semantic
 	 * element; otherwise <tt>false</tt> to delete its view. A <tt>true</tt>
 	 * return value implies that the host's parent is using a canonical
 	 * model manager.
 	 * @return true or false
 	 */
 	protected boolean shouldDeleteSemantic() {
 		EditPart parent = getHost().getParent();
         if (parent instanceof SemanticListCompartmentEditPart){
             SemanticListCompartmentEditPart semListCompartment  =
                 (SemanticListCompartmentEditPart)parent;
             return semListCompartment.isCanonicalOn();

         } else {

             // If the parent is a group, then we want to get the first parent
             // that isn't a group and test for a canonical editpolicy there.
             while (parent instanceof GroupEditPart) {
                 parent = parent.getParent();
             }
         }

         EObject eObject = (EObject)getHost().getAdapter(EObject.class);
         if (eObject != null && parent != null ) { //sanity checks
 			CanonicalEditPolicy cep = (CanonicalEditPolicy)parent.getEditPolicy(EditPolicyRoles.CANONICAL_ROLE);
 			return cep != null
 				&& cep.isEnabled()
 				&& cep.canCreate(eObject);
 		}
 		return false;
 	}

 	/**
 	 * Return a command to delete the host's view.  The host's primary view
 	 * is deleted if {@link GroupRequest#getEditParts()} returns a
 	 * <tt>null</tt> or empty list; otherwise each editpart's view is
 	 * deleted.
 	 * @param deleteRequest the original delete request.
 	 * @return Command
 	 */
 	protected Command createDeleteViewCommand(GroupRequest deleteRequest) {
 		CompositeCommand cc = new CompositeCommand(StringStatics.BLANK);

         TransactionalEditingDomain editingDomain = getEditingDomain();
 		if (editingDomain == null) {
 			return null;
 		}
 		List toDel = deleteRequest.getEditParts();
 		if (toDel == null || toDel.isEmpty()) {
 			cc.compose(new DeleteCommand(editingDomain, (View) getHost()
 				.getModel()));
 		} else {
 			for (int i = 0; i < toDel.size(); i++) {
 				IGraphicalEditPart gep = (IGraphicalEditPart) toDel.get(i);
 				cc.compose(new DeleteCommand(editingDomain, (View) gep
 					.getModel()));
 			}
 		}
 		return new ICommandProxy(cc.reduce());
 	}

 	/**
 	 * Return a command to delete the host's semantic elements. This method is
 	 * called if the host is canonical.
 	 *
 	 * @see #shouldDeleteSemantic()
 	 * @param deleteRequest
 	 *            the original delete request.
 	 * @return Command
 	 */
 	protected Command createDeleteSemanticCommand(GroupRequest deleteRequest) {
         TransactionalEditingDomain editingDomain = ((IGraphicalEditPart) getHost()).getEditingDomain();

            boolean shouldShowPrompt = (deleteRequest instanceof GroupRequestViaKeyboard) ? ((GroupRequestViaKeyboard) deleteRequest)
             .isShowInformationDialog()
             : false;

         EditCommandRequestWrapper editCommandRequest = new EditCommandRequestWrapper(
             new DestroyElementRequest(editingDomain, shouldShowPrompt),
             deleteRequest.getExtendedData());

 		Command semanticCmd = getHost().getCommand(editCommandRequest);
 		if (semanticCmd != null && semanticCmd.canExecute()) {
 			CompoundCommand cc = new CompoundCommand();
 			cc.add(semanticCmd);
 			return cc;
 		}
 		return createDeleteViewCommand(deleteRequest);
 	}

 	/**
 	 * Returns the view element to be deleted.
 	 * @return the host's primary view element.
 	 */
 	protected View getView() {
 	   if (getHost().getModel() instanceof View &&
 			getHost() instanceof GraphicalEditPart){
 			GraphicalEditPart ePart = (GraphicalEditPart)getHost();
 			return ePart.getPrimaryView();
 		}
 		return null;
 	}


 	/**
 	 * Performs the delete action on the selected objects.
 	 */
 	private boolean showPrompt() {
 		boolean prompt = ((IPreferenceStore) ((IGraphicalEditPart) getHost())
 			.getDiagramPreferencesHint().getPreferenceStore())
 			.getBoolean(IPreferenceConstants.PREF_PROMPT_ON_DEL_FROM_DIAGRAM);

 		if(prompt)
 			if(showMessageDialog())
 				return true;
 			else
 				return false;

 		return true;

 	}

 	/**
 	 * launches the prompting dialogBox on deletion of elements from the diagram for the end user.
 	 *
 	 * @return boolean  true if user pressed YES; false otherwise
 	 */
 	private boolean showMessageDialog() {
 		MessageDialogWithToggle dialog = MessageDialogWithToggle
 			.openYesNoQuestion(Display.getCurrent().getActiveShell(),
 				DELETE_FROM_DIAGRAM_DLG_TITLE, DELETE_FROM_DIAGRAM_DLG_MESSAGE,
 				DELETE_FROM_MODEL_DLG_TOGGLE_LABEL, false,
 				(IPreferenceStore) ((IGraphicalEditPart) getHost())
 					.getDiagramPreferencesHint().getPreferenceStore(),
 				IPreferenceConstants.PREF_PROMPT_ON_DEL_FROM_DIAGRAM);

 		if (dialog.getReturnCode() == IDialogConstants.YES_ID)
 			return true;
 		else
 			return false;
 	}

 	/**
 	 * getInsertableEditPart
 	 * Returns the EditPart that can be recipient of the default insert command.
 	 *
 	 * @return IInsertableEditPart
 	 */
 	protected IInsertableEditPart getInsertableEditPart() {
 		if (getHost() instanceof IInsertableEditPart) {
 			return (IInsertableEditPart)getHost();
 		}

 		return null;
 	}

 	/**
 	 * getInsertCommand
 	 * Returns an creation command to honour the supplied request.
 	 *
 	 * @param insertRequest
 	 * @return Command that will create the default sementic element responding to insert.
 	 */
 	protected Command getInsertCommand(GroupRequest insertRequest) {
 		IInsertableEditPart insertEP = getInsertableEditPart();
 		if (null == insertEP)
 			return null;

 		EObject hostElement = ViewUtil.resolveSemanticElement((View)insertEP.getModel());
 		if (hostElement != null) {

             TransactionalEditingDomain editingDomain = getEditingDomain();
             if (editingDomain == null) {
                 return null;
             }

             CreateElementRequest theReq = new CreateElementRequest(
                  editingDomain, hostElement, insertEP.getElementType());

             EditCommandRequestWrapper editCommandRequest = new EditCommandRequestWrapper(
                 theReq, insertRequest.getExtendedData());
             Command cmd = ((IGraphicalEditPart) getHost())
                 .getCommand(editCommandRequest);

             return cmd;
 		}

 		return null;
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.gef.editpolicies.ComponentEditPolicy#getCommand(org.eclipse.gef.Request)
 	 */
 	public Command getCommand(Request request) {
 		if (!(request instanceof GroupRequest))
 			return null;

 		GroupRequest grpRequest = (GroupRequest)request;
 		if (grpRequest instanceof GroupRequestViaKeyboard){
 			return getDeleteCommand(grpRequest);
 		}
 		else if (grpRequest.getType().equals(RequestConstants.REQ_INSERT_SEMANTIC)) {
 			return getInsertCommand(grpRequest);
 		}

 		return super.getCommand(request);
 	}

     private TransactionalEditingDomain getEditingDomain() {
          if (getHost() instanceof IGraphicalEditPart) {
             return ((IGraphicalEditPart) getHost()).getEditingDomain();
         } else if (getHost() instanceof IEditingDomainProvider) {
             Object domain = ((IEditingDomainProvider) getHost())
                 .getEditingDomain();
             if (domain instanceof TransactionalEditingDomain) {
                 return (TransactionalEditingDomain) domain;
             }
         }
         return null;
     }

  }
	/******************************************************************************
	* Copyright (c) 2002, 2008 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.List;

	import org.eclipse.emf.ecore.EObject;
	import org.eclipse.emf.edit.domain.IEditingDomainProvider;
	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.CompoundCommand;
	import org.eclipse.gef.commands.UnexecutableCommand;
	import org.eclipse.gef.requests.GroupRequest;
	import org.eclipse.gmf.runtime.common.core.command.CompositeCommand;
	import org.eclipse.gmf.runtime.common.core.util.StringStatics;
	import org.eclipse.gmf.runtime.diagram.core.commands.DeleteCommand;
	import org.eclipse.gmf.runtime.diagram.core.util.ViewUtil;
	import org.eclipse.gmf.runtime.diagram.ui.commands.ICommandProxy;
	import org.eclipse.gmf.runtime.diagram.ui.editparts.GraphicalEditPart;
	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.IInsertableEditPart;
	import org.eclipse.gmf.runtime.diagram.ui.editparts.SemanticListCompartmentEditPart;
	import org.eclipse.gmf.runtime.diagram.ui.l10n.DiagramUIMessages;
	import org.eclipse.gmf.runtime.diagram.ui.preferences.IPreferenceConstants;
	import org.eclipse.gmf.runtime.diagram.ui.requests.EditCommandRequestWrapper;
	import org.eclipse.gmf.runtime.diagram.ui.requests.GroupRequestViaKeyboard;
	import org.eclipse.gmf.runtime.diagram.ui.requests.RequestConstants;
	import org.eclipse.gmf.runtime.emf.type.core.requests.CreateElementRequest;
	import org.eclipse.gmf.runtime.emf.type.core.requests.DestroyElementRequest;
	import org.eclipse.gmf.runtime.notation.View;
	import org.eclipse.jface.dialogs.IDialogConstants;
	import org.eclipse.jface.dialogs.MessageDialogWithToggle;
	import org.eclipse.jface.preference.IPreferenceStore;
	import org.eclipse.swt.widgets.Display;

	/**
	* Concrete class that extends the GEF's <code>ComponentEditPolicy</code>.
	* This edit policy will return a command in response to delete requests.
	*
	* @author Vishy Ramaswamy
	*/
	public class ComponentEditPolicy
	extends org.eclipse.gef.editpolicies.ComponentEditPolicy {

	private static final String DELETE_FROM_DIAGRAM_DLG_TITLE = DiagramUIMessages.PromptingDeleteAction_DeleteFromDiagramDialog_Title;

	private static final String DELETE_FROM_DIAGRAM_DLG_MESSAGE = DiagramUIMessages.PromptingDeleteAction_DeleteFromDiagramDialog_Message;

	private static final String DELETE_FROM_MODEL_DLG_TOGGLE_LABEL = DiagramUIMessages.MessageDialogWithToggle_DoNotPromptAgainToggle_label;


	/**
	* Returns a delete command to honour the supplied request.
	* Calls {@link #createDeleteSemanticCommand(GroupRequest)} if
	* {@link #shouldDeleteSemantic()} returns <tt>true</tt>; othwerise
	* {@link #createDeleteViewCommand(GroupRequest)} is called.
	* @see org.eclipse.gef.editpolicies.ComponentEditPolicy#createDeleteCommand(GroupRequest)
	*/
	protected final Command createDeleteCommand(GroupRequest deleteRequest) {

	if (shouldDeleteSemantic()){
	return createDeleteSemanticCommand(deleteRequest);
	}
	if (deleteRequest instanceof GroupRequestViaKeyboard) {
	boolean shouldShowPrompt = ((GroupRequestViaKeyboard) deleteRequest)
	.isShowInformationDialog();
	if (shouldShowPrompt) {
	((GroupRequestViaKeyboard) deleteRequest)
	.setShowInformationDialog(false);
	if (showPrompt() == false) {
	return UnexecutableCommand.INSTANCE;
	}
	}
	}
	return createDeleteViewCommand(deleteRequest);

	}

	/**
	* Return <tt>true</tt> if the host element should delete its semantic
	* element; otherwise <tt>false</tt> to delete its view. A <tt>true</tt>
	* return value implies that the host's parent is using a canonical
	* model manager.
	* @return true or false
	*/
	protected boolean shouldDeleteSemantic() {
	EditPart parent = getHost().getParent();
	if (parent instanceof SemanticListCompartmentEditPart){
	SemanticListCompartmentEditPart semListCompartment =
	(SemanticListCompartmentEditPart)parent;
	return semListCompartment.isCanonicalOn();

	} else {

	// If the parent is a group, then we want to get the first parent
	// that isn't a group and test for a canonical editpolicy there.
	while (parent instanceof GroupEditPart) {
	parent = parent.getParent();
	}
	}

	EObject eObject = (EObject)getHost().getAdapter(EObject.class);
	if (eObject != null && parent != null ) { //sanity checks
	CanonicalEditPolicy cep = (CanonicalEditPolicy)parent.getEditPolicy(EditPolicyRoles.CANONICAL_ROLE);
	return cep != null
	&& cep.isEnabled()
	&& cep.canCreate(eObject);
	}
	return false;
	}

	/**
	* Return a command to delete the host's view. The host's primary view
	* is deleted if {@link GroupRequest#getEditParts()} returns a
	* <tt>null</tt> or empty list; otherwise each editpart's view is
	* deleted.
	* @param deleteRequest the original delete request.
	* @return Command
	*/
	protected Command createDeleteViewCommand(GroupRequest deleteRequest) {
	CompositeCommand cc = new CompositeCommand(StringStatics.BLANK);

	TransactionalEditingDomain editingDomain = getEditingDomain();
	if (editingDomain == null) {
	return null;
	}
	List toDel = deleteRequest.getEditParts();
	if (toDel == null \|\| toDel.isEmpty()) {
	cc.compose(new DeleteCommand(editingDomain, (View) getHost()
	.getModel()));
	} else {
	for (int i = 0; i < toDel.size(); i++) {
	IGraphicalEditPart gep = (IGraphicalEditPart) toDel.get(i);
	cc.compose(new DeleteCommand(editingDomain, (View) gep
	.getModel()));
	}
	}
	return new ICommandProxy(cc.reduce());
	}

	/**
	* Return a command to delete the host's semantic elements. This method is
	* called if the host is canonical.
	*
	* @see #shouldDeleteSemantic()
	* @param deleteRequest
	* the original delete request.
	* @return Command
	*/
	protected Command createDeleteSemanticCommand(GroupRequest deleteRequest) {
	TransactionalEditingDomain editingDomain = ((IGraphicalEditPart) getHost()).getEditingDomain();

	boolean shouldShowPrompt = (deleteRequest instanceof GroupRequestViaKeyboard) ? ((GroupRequestViaKeyboard) deleteRequest)
	.isShowInformationDialog()
	: false;

	EditCommandRequestWrapper editCommandRequest = new EditCommandRequestWrapper(
	new DestroyElementRequest(editingDomain, shouldShowPrompt),
	deleteRequest.getExtendedData());

	Command semanticCmd = getHost().getCommand(editCommandRequest);
	if (semanticCmd != null && semanticCmd.canExecute()) {
	CompoundCommand cc = new CompoundCommand();
	cc.add(semanticCmd);
	return cc;
	}
	return createDeleteViewCommand(deleteRequest);
	}

	/**
	* Returns the view element to be deleted.
	* @return the host's primary view element.
	*/
	protected View getView() {
	if (getHost().getModel() instanceof View &&
	getHost() instanceof GraphicalEditPart){
	GraphicalEditPart ePart = (GraphicalEditPart)getHost();
	return ePart.getPrimaryView();
	}
	return null;
	}


	/**
	* Performs the delete action on the selected objects.
	*/
	private boolean showPrompt() {
	boolean prompt = ((IPreferenceStore) ((IGraphicalEditPart) getHost())
	.getDiagramPreferencesHint().getPreferenceStore())
	.getBoolean(IPreferenceConstants.PREF_PROMPT_ON_DEL_FROM_DIAGRAM);

	if(prompt)
	if(showMessageDialog())
	return true;
	else
	return false;

	return true;

	}

	/**
	* launches the prompting dialogBox on deletion of elements from the diagram for the end user.
	*
	* @return boolean true if user pressed YES; false otherwise
	*/
	private boolean showMessageDialog() {
	MessageDialogWithToggle dialog = MessageDialogWithToggle
	.openYesNoQuestion(Display.getCurrent().getActiveShell(),
	DELETE_FROM_DIAGRAM_DLG_TITLE, DELETE_FROM_DIAGRAM_DLG_MESSAGE,
	DELETE_FROM_MODEL_DLG_TOGGLE_LABEL, false,
	(IPreferenceStore) ((IGraphicalEditPart) getHost())
	.getDiagramPreferencesHint().getPreferenceStore(),
	IPreferenceConstants.PREF_PROMPT_ON_DEL_FROM_DIAGRAM);

	if (dialog.getReturnCode() == IDialogConstants.YES_ID)
	return true;
	else
	return false;
	}

	/**
	* getInsertableEditPart
	* Returns the EditPart that can be recipient of the default insert command.
	*
	* @return IInsertableEditPart
	*/
	protected IInsertableEditPart getInsertableEditPart() {
	if (getHost() instanceof IInsertableEditPart) {
	return (IInsertableEditPart)getHost();
	}

	return null;
	}

	/**
	* getInsertCommand
	* Returns an creation command to honour the supplied request.
	*
	* @param insertRequest
	* @return Command that will create the default sementic element responding to insert.
	*/
	protected Command getInsertCommand(GroupRequest insertRequest) {
	IInsertableEditPart insertEP = getInsertableEditPart();
	if (null == insertEP)
	return null;

	EObject hostElement = ViewUtil.resolveSemanticElement((View)insertEP.getModel());
	if (hostElement != null) {

	TransactionalEditingDomain editingDomain = getEditingDomain();
	if (editingDomain == null) {
	return null;
	}

	CreateElementRequest theReq = new CreateElementRequest(
	editingDomain, hostElement, insertEP.getElementType());

	EditCommandRequestWrapper editCommandRequest = new EditCommandRequestWrapper(
	theReq, insertRequest.getExtendedData());
	Command cmd = ((IGraphicalEditPart) getHost())
	.getCommand(editCommandRequest);

	return cmd;
	}

	return null;
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.gef.editpolicies.ComponentEditPolicy#getCommand(org.eclipse.gef.Request)
	*/
	public Command getCommand(Request request) {
	if (!(request instanceof GroupRequest))
	return null;

	GroupRequest grpRequest = (GroupRequest)request;
	if (grpRequest instanceof GroupRequestViaKeyboard){
	return getDeleteCommand(grpRequest);
	}
	else if (grpRequest.getType().equals(RequestConstants.REQ_INSERT_SEMANTIC)) {
	return getInsertCommand(grpRequest);
	}

	return super.getCommand(request);
	}

	private TransactionalEditingDomain getEditingDomain() {
	if (getHost() instanceof IGraphicalEditPart) {
	return ((IGraphicalEditPart) getHost()).getEditingDomain();
	} else if (getHost() instanceof IEditingDomainProvider) {
	Object domain = ((IEditingDomainProvider) getHost())
	.getEditingDomain();
	if (domain instanceof TransactionalEditingDomain) {
	return (TransactionalEditingDomain) domain;
	}
	}
	return null;
	}

	}