plugins/diagram/org.eclipse.papyrus.sysml.diagram.common/src-common-gmf/org/eclipse/papyrus/gmf/diagram/common/edit/policy/CommonDiagramDragDropEditPolicy.java - papyrus/org.eclipse.papyrus-sysml11 - Git at Google

 /*****************************************************************************
  * Copyright (c) 2011 CEA LIST.
  *
  * 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:
  *
  *		CEA LIST - Initial API and implementation
  *
  *****************************************************************************/
 package org.eclipse.papyrus.gmf.diagram.common.edit.policy;

 import static org.eclipse.papyrus.infra.gmfdiag.common.providers.IGraphicalTypeRegistry.UNDEFINED_TYPE;

 import java.util.Collection;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Set;

 import org.eclipse.core.runtime.IAdaptable;
 import org.eclipse.draw2d.geometry.Point;
 import org.eclipse.emf.ecore.EObject;
 import org.eclipse.emf.transaction.TransactionalEditingDomain;
 import org.eclipse.gef.EditPart;
 import org.eclipse.gef.EditPartViewer;
 import org.eclipse.gef.commands.Command;
 import org.eclipse.gef.commands.CompoundCommand;
 import org.eclipse.gef.commands.UnexecutableCommand;
 import org.eclipse.gef.requests.ChangeBoundsRequest;
 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.ICommand;
 import org.eclipse.gmf.runtime.diagram.core.preferences.PreferencesHint;
 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.IGraphicalEditPart;
 import org.eclipse.gmf.runtime.diagram.ui.editpolicies.DiagramDragDropEditPolicy;
 import org.eclipse.gmf.runtime.diagram.ui.requests.ArrangeRequest;
 import org.eclipse.gmf.runtime.diagram.ui.requests.CreateConnectionViewRequest;
 import org.eclipse.gmf.runtime.diagram.ui.requests.CreateViewRequest;
 import org.eclipse.gmf.runtime.diagram.ui.requests.CreateViewRequest.ViewDescriptor;
 import org.eclipse.gmf.runtime.diagram.ui.requests.DropObjectsRequest;
 import org.eclipse.gmf.runtime.diagram.ui.requests.RefreshConnectionsRequest;
 import org.eclipse.gmf.runtime.diagram.ui.requests.RequestConstants;
 import org.eclipse.gmf.runtime.emf.core.util.EObjectAdapter;
 import org.eclipse.gmf.runtime.notation.Diagram;
 import org.eclipse.gmf.runtime.notation.Node;
 import org.eclipse.gmf.runtime.notation.View;
 import org.eclipse.papyrus.commands.wrappers.CommandProxyWithResult;
 import org.eclipse.papyrus.gmf.diagram.common.provider.IGraphicalTypeRegistry;
 import org.eclipse.papyrus.infra.gmfdiag.common.commands.DeferredSnapToGridCommand;
 import org.eclipse.papyrus.infra.gmfdiag.common.preferences.PreferencesConstantsHelper;
 import org.eclipse.papyrus.infra.gmfdiag.common.utils.ViewDescriptorUtil;
 import org.eclipse.papyrus.uml.diagram.common.commands.CommonDeferredCreateConnectionViewCommand;
 import org.eclipse.papyrus.uml.diagram.common.commands.SemanticAdapter;
 import org.eclipse.papyrus.uml.diagram.common.edit.part.AbstractElementBorderEditPart;
 import org.eclipse.papyrus.uml.diagram.common.edit.part.AbstractElementLabelEditPart;
 import org.eclipse.papyrus.uml.diagram.common.helper.Element2IAdaptableRegistryHelper;
 import org.eclipse.papyrus.uml.diagram.common.util.CrossReferencerUtil;
 import org.eclipse.uml2.uml.Classifier;
 import org.eclipse.uml2.uml.Element;

 /**
  * Abstract DND edit policy delegating the choice of the view to create for an EObject to a local
  * graphical type registry.
  */
 public abstract class CommonDiagramDragDropEditPolicy extends DiagramDragDropEditPolicy {

 	private Element2IAdaptableRegistryHelper myElement2IAdaptableRegistryHelper;

 	/** The graphical type registry. */
 	protected IGraphicalTypeRegistry registry;

 	/** The list of element types that require a specific drop command. */
 	private Set<String> specificDropList = null;

 	/** The specified link mapping helper depending on the diagram */
 	protected ILinkMappingHelper linkMappingHelper;

 	/** Constructor */
 	public CommonDiagramDragDropEditPolicy(ILinkMappingHelper linkMappingHelper) {
 		this.linkMappingHelper = linkMappingHelper;
 	}

 	private Set<String> getSpecificDropList() {
 		if (specificDropList == null) {
 			specificDropList = getSpecificDropBehaviorTypes();
 		}
 		return specificDropList;
 	}

 	/**
 	 * Gets composite command adapters
 	 */
 	protected Element2IAdaptableRegistryHelper getElement2IAdaptableRegistryHelper() {
 		if (myElement2IAdaptableRegistryHelper == null) {
 			myElement2IAdaptableRegistryHelper = new Element2IAdaptableRegistryHelper();
 		}
 		return myElement2IAdaptableRegistryHelper;
 	}

 	protected abstract Set<String> getSpecificDropBehaviorTypes();

 	/**
 	 * <pre>
 	 * {@inheritedDoc}.
 	 *
 	 * Overridden method to fix some exception occurring while moving affixed element (nodes or labels)
 	 * (https://bugs.eclipse.org/bugs/show_bug.cgi?id=350680).
 	 * </pre>
 	 */
 	@Override
 	protected Command getDropCommand(ChangeBoundsRequest request) {

 		Iterator<?> iter = request.getEditParts().iterator();
 		EObject graphicalParentObject = ((GraphicalEditPart) getHost()).resolveSemanticElement();
 		while ((graphicalParentObject != null) && (iter.hasNext())) {
 			EditPart droppedEditPart = (EditPart) iter.next();
 			if (droppedEditPart instanceof AbstractElementBorderEditPart) {
 				return UnexecutableCommand.INSTANCE;
 			}
 			if (droppedEditPart instanceof AbstractElementLabelEditPart) {
 				return UnexecutableCommand.INSTANCE;
 			}
 		}
 		return super.getDropCommand(request);
 	}

 	/**
 	 * {@inheritedDoc}.
 	 */
 	@Override
 	public Command getDropObjectsCommand(DropObjectsRequest dropRequest) {

 		CompoundCommand completeDropCommand = new CompoundCommand("DropObjectsAndArrange"); //$NON-NLS-1$

 		// Detect file drop
 		if ((dropRequest.getObjects().size() > 0) && (dropRequest.getObjects().get(0) instanceof String)) {
 			return getDropFileCommand(dropRequest);
 		}

 		// Create the drop command by composite drop command for each dropped elements
 		CompositeCommand gmfDropCommand = new CompositeCommand("DropObjects"); //$NON-NLS-1$
 		Iterator<?> iter = dropRequest.getObjects().iterator();
 		while (iter.hasNext()) {
 			EObject droppedObject = (EObject) iter.next();
 			gmfDropCommand.add(getDropObjectCommand(dropRequest, droppedObject));
 		}

 		// Create the complete drop command by adding an arrange command after drop
 		if (!gmfDropCommand.isEmpty()) {

 			// Retrieve drop result (most probably created view but not necessarily) and update the request
 			CommandResult result = gmfDropCommand.getCommandResult();
 			List<?> newValues = (List<?>) result.getReturnValue();
 			dropRequest.setResult(newValues);

 			// Prepare refresh command
 			RefreshConnectionsRequest refreshRequest = new RefreshConnectionsRequest(newValues);
 			Command refreshCommand = getHost().getCommand(refreshRequest);

 			// Prepare an arrange command to avoid every dropped view to appear at the same location only if newValues contains at least one node, not when you just drag a link
 			boolean isOneNode = false;
 			for(Object o : newValues){
 				if(o instanceof Node){
 					isOneNode=true;
 					break;
 				}
 			}

 			ArrangeRequest arrangeRequest = new ArrangeRequest(RequestConstants.REQ_ARRANGE_DEFERRED);
 			arrangeRequest.setViewAdaptersToArrange(newValues);
 			Command arrangeCommand = getHost().getCommand(arrangeRequest);

 			// Update the complete drop command (drop - refresh - arrange)
 			Command dropCommand = new ICommandProxy(gmfDropCommand);
 			completeDropCommand.add(dropCommand.chain(refreshCommand));
 			if(isOneNode){
 				completeDropCommand.add(arrangeCommand);
 			}

 			// add snap command if required
 			// 430099: [Diagram] Snap to Grid for elements dropped from the ModelExplorer is ignored
 			// https://bugs.eclipse.org/bugs/show_bug.cgi?id=430099
 			final Object value = dropRequest.getExtendedData().get(PreferencesConstantsHelper.SNAP_TO_GRID_CONSTANT);
 			if (value instanceof Boolean && Boolean.TRUE.equals(value)) {
 				DeferredSnapToGridCommand snapCommand = new DeferredSnapToGridCommand(getEditingDomain(), newValues, (IGraphicalEditPart) getHost());
 				completeDropCommand.add(new ICommandProxy(snapCommand));
 			}

 		}

 		return completeDropCommand;
 	}

 	protected ICommand getDropObjectCommand(DropObjectsRequest dropRequest, EObject droppedObject) {

 		Point location = dropRequest.getLocation().getCopy();

 		View dropTargetView = ((IGraphicalEditPart) getHost()).getNotationView();

 		String droppedNodeType = registry.getNodeGraphicalType(droppedObject, dropTargetView.getType());
 		String droppedEdgeType = registry.getEdgeGraphicalType(droppedObject);

 		// Test if a specific drop command should be used
 		if (getSpecificDropList().contains(droppedNodeType) || getSpecificDropList().contains(droppedEdgeType)) {
 			return getSpecificDropCommand(dropRequest, droppedObject, droppedNodeType, droppedEdgeType);
 		}

 		// Decide unknown type handling
 		if (UNDEFINED_TYPE.equals(droppedNodeType) && UNDEFINED_TYPE.equals(droppedEdgeType)) {
 			return getUnknownDropCommand(dropRequest, droppedObject);
 		}

 		// The dropped element is a node
 		if (!UNDEFINED_TYPE.equals(droppedNodeType)) {
 			return getDefaultDropNodeCommand(droppedNodeType, droppedObject, location);
 		}

 		// The dropped element is a edge
 		if (!UNDEFINED_TYPE.equals(droppedEdgeType)) {

 			Collection<?> sources = linkMappingHelper.getSource((Element) droppedObject);
 			Collection<?> targets = linkMappingHelper.getTarget((Element) droppedObject);

 			// Only manage binary link during drop
 			if ((sources.size() > 0) && (targets.size() > 0)) {
 				EObject source = (EObject) sources.toArray()[0];
 				EObject target = (EObject) targets.toArray()[0];
 				return getDefaultDropEdgeCommand(droppedObject, source, target, droppedEdgeType, location);
 			}

 			return org.eclipse.gmf.runtime.common.core.command.UnexecutableCommand.INSTANCE;
 		}

 		return org.eclipse.gmf.runtime.common.core.command.UnexecutableCommand.INSTANCE;
 	}

 	protected ICommand getDefaultDropNodeCommand(String droppedNodeType, EObject droppedObject, Point location) {
 		View dropTargetView = ((IGraphicalEditPart) getHost()).getNotationView();
 		EObject dropTargetElement = dropTargetView.getElement();
 		// Drop restriction:
 		// - no restriction when dropped on diagram
 		// - require containment when dropped on any other EObject
 		if ((dropTargetView instanceof Diagram) || dropTargetElement.eContents().contains(droppedObject)) {
 			return getDefaultDropNodeCommand(droppedNodeType, location, droppedObject);
 		}

 		// Allow drop for inherited elements
 		if (dropTargetElement instanceof Classifier && ((Classifier) dropTargetElement).getAllAttributes().contains(droppedObject)) {
 			return getDefaultDropNodeCommand(droppedNodeType, location, droppedObject);
 		}
 		return org.eclipse.gmf.runtime.common.core.command.UnexecutableCommand.INSTANCE;
 	}

 	protected ICommand getDefaultDropNodeCommand(String droppedObjectGraphicalType, Point absoluteLocation, EObject droppedObject) {

 		IAdaptable elementAdapter = new EObjectAdapter(droppedObject);

 		ViewDescriptor descriptor = new ViewDescriptor(elementAdapter, Node.class, droppedObjectGraphicalType, ViewUtil.APPEND, ViewDescriptorUtil.PERSISTED, getDiagramPreferencesHint());
 		CreateViewRequest createViewRequest = new CreateViewRequest(descriptor);
 		createViewRequest.setLocation(absoluteLocation);

 		// Get view creation command for the dropped object
 		Command command = getHost().getCommand(createViewRequest);

 		// Use the ViewDescriptor as command result, it then can be used as an adaptable to retrieve the View
 		return new CommandProxyWithResult(command, descriptor);
 	}

 	protected ICommand getDefaultDropEdgeCommand(EObject droppedObject, EObject source, EObject target, String droppedEdgeType, Point absoluteLocation) {

 		CompositeCommand completeDropCommand = new CompositeCommand("CompleteDropEdge"); //$NON-NLS-1$

 		// Find views in current diagram representing source and target
 		Collection<View> sourceViews = getViews(source);
 		Collection<View> targetViews = getViews(target);

 		IAdaptable sourceViewAdapter = null;
 		IAdaptable targetViewAdapter = null;

 		// If either a source or target lacks create view for these elements
 		// - using defaultDrop command (assumed to be a view creation)
 		// - try to create view on host
 		if (sourceViews.isEmpty() || targetViews.isEmpty()) {

 			CompositeCommand createEndViewsCommand = new CompositeCommand("CreateSourceTargetViews"); //$NON-NLS-1$

 			View dropContainerView = ((IGraphicalEditPart) getHost()).getNotationView();
 			EObject dropContainerElement = dropContainerView.getElement();

 			if (sourceViews.isEmpty()) {
 				if (dropContainerElement.eContents().contains(source)) {
 					ICommand dropSourceCommand = getDefaultDropNodeCommand(registry.getNodeGraphicalType(source, dropContainerView.getType()), absoluteLocation.getCopy(), source);
 					CompositeCommand.compose(createEndViewsCommand, dropSourceCommand);
 					sourceViewAdapter = (IAdaptable) dropSourceCommand.getCommandResult().getReturnValue();
 				} else {
 					return org.eclipse.gmf.runtime.common.core.command.UnexecutableCommand.INSTANCE;
 				}
 			}

 			if (targetViews.isEmpty()) {
 				if (dropContainerElement.eContents().contains(target)) {
 					ICommand dropTargetCommand = getDefaultDropNodeCommand(registry.getNodeGraphicalType(target, dropContainerView.getType()), absoluteLocation.getCopy(), target);
 					CompositeCommand.compose(createEndViewsCommand, dropTargetCommand);
 					targetViewAdapter = (IAdaptable) dropTargetCommand.getCommandResult().getReturnValue();
 				} else {
 					return org.eclipse.gmf.runtime.common.core.command.UnexecutableCommand.INSTANCE;
 				}
 			}

 			CompositeCommand.compose(completeDropCommand, createEndViewsCommand);
 		}

 		// Create source adapter
 		if (!sourceViews.isEmpty()) { // sourceViewAdapter should still be null in this case
 			sourceViewAdapter = new SemanticAdapter(null, sourceViews.toArray()[0]);
 		}

 		// Create target adapter
 		if (!targetViews.isEmpty()) { // targetViewAdapter should still be null in this case
 			targetViewAdapter = new SemanticAdapter(null, targetViews.toArray()[0]);
 		}

 		// Create a view for the dropped link between the source and target view adapters
 		IAdaptable droppedObjectAdapter = new SemanticAdapter(droppedObject, null);

 		CreateConnectionViewRequest.ConnectionViewDescriptor linkdescriptor = new CreateConnectionViewRequest.ConnectionViewDescriptor(droppedObjectAdapter, droppedEdgeType, getDiagramPreferencesHint());

 		CommonDeferredCreateConnectionViewCommand createConnectionViewCommand = new CommonDeferredCreateConnectionViewCommand(getEditingDomain(), droppedEdgeType, sourceViewAdapter, targetViewAdapter, getViewer(), getDiagramPreferencesHint(), linkdescriptor,
 				null);
 		createConnectionViewCommand.setElement(droppedObject);

 		CompositeCommand.compose(completeDropCommand, createConnectionViewCommand);

 		return completeDropCommand.reduce();
 	}

 	/**
 	 * <pre>
 	 * Sub-classes have to implement this method in order to provides specific drop command for
 	 * element which require a specific treatment.
 	 *
 	 * @param dropRequest current drop request
 	 * @param droppedEObject the dropped object
 	 * @param nodeType the graphical type of the dropped element (node representation)
 	 * @param edgeType the graphical type of the dropped element (edge representation)
 	 * @return the drop command
 	 * </pre>
 	 */
 	protected ICommand getSpecificDropCommand(DropObjectsRequest dropRequest, EObject droppedEObject, String nodeType, String edgeType) {
 		return org.eclipse.gmf.runtime.common.core.command.UnexecutableCommand.INSTANCE;
 	}

 	/**
 	 * <pre>
 	 * Sub-classes have to implement this method in order to provides drop command for
 	 * elements that are not natively known by the diagram.
 	 *
 	 * @param dropRequest current drop request
 	 * @param droppedEObject the dropped object
 	 * @return the drop command
 	 * </pre>
 	 */
 	protected ICommand getUnknownDropCommand(DropObjectsRequest dropRequest, EObject droppedEObject) {
 		return org.eclipse.gmf.runtime.common.core.command.UnexecutableCommand.INSTANCE;
 	}

 	protected EditPartViewer getViewer() {
 		return ((IGraphicalEditPart) getHost()).getViewer();
 	}

 	protected TransactionalEditingDomain getEditingDomain() {
 		return ((IGraphicalEditPart) getHost()).getEditingDomain();
 	}

 	protected PreferencesHint getDiagramPreferencesHint() {
 		return ((IGraphicalEditPart) getHost()).getDiagramPreferencesHint();
 	}

 	/**
 	 * This methods looks for views representing a given EObject in the host diagram.
 	 *
 	 * @param eObject
 	 *            the {@link EObject} to look for.
 	 * @return the list of {@link View} representing the eObject.
 	 */
 	private Set<View> getViews(EObject eObject) {
 		Set<View> views = new HashSet<View>();

 		// Retrieve host diagram
 		View hostView = ((IGraphicalEditPart) getHost()).getNotationView();
 		View hostDiagram = (hostView instanceof Diagram) ? hostView : hostView.getDiagram();

 		// Retrieve all views for the eObject
 		Collection<View> relatedViews = CrossReferencerUtil.getCrossReferencingViews(eObject, hostDiagram.getType());

 		// Parse and select views from host diagram only
 		Iterator<View> it = relatedViews.iterator();
 		while (it.hasNext()) {
 			View currentView = it.next();
 			if (!(currentView instanceof Diagram) && (currentView.getDiagram() == hostDiagram)) {
 				views.add(currentView);
 			}
 		}

 		return views;
 	}
 }
	/*****************************************************************************
	* Copyright (c) 2011 CEA LIST.
	*
	* 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:
	*
	* CEA LIST - Initial API and implementation
	*
	*****************************************************************************/
	package org.eclipse.papyrus.gmf.diagram.common.edit.policy;

	import static org.eclipse.papyrus.infra.gmfdiag.common.providers.IGraphicalTypeRegistry.UNDEFINED_TYPE;

	import java.util.Collection;
	import java.util.HashSet;
	import java.util.Iterator;
	import java.util.List;
	import java.util.Set;

	import org.eclipse.core.runtime.IAdaptable;
	import org.eclipse.draw2d.geometry.Point;
	import org.eclipse.emf.ecore.EObject;
	import org.eclipse.emf.transaction.TransactionalEditingDomain;
	import org.eclipse.gef.EditPart;
	import org.eclipse.gef.EditPartViewer;
	import org.eclipse.gef.commands.Command;
	import org.eclipse.gef.commands.CompoundCommand;
	import org.eclipse.gef.commands.UnexecutableCommand;
	import org.eclipse.gef.requests.ChangeBoundsRequest;
	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.ICommand;
	import org.eclipse.gmf.runtime.diagram.core.preferences.PreferencesHint;
	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.IGraphicalEditPart;
	import org.eclipse.gmf.runtime.diagram.ui.editpolicies.DiagramDragDropEditPolicy;
	import org.eclipse.gmf.runtime.diagram.ui.requests.ArrangeRequest;
	import org.eclipse.gmf.runtime.diagram.ui.requests.CreateConnectionViewRequest;
	import org.eclipse.gmf.runtime.diagram.ui.requests.CreateViewRequest;
	import org.eclipse.gmf.runtime.diagram.ui.requests.CreateViewRequest.ViewDescriptor;
	import org.eclipse.gmf.runtime.diagram.ui.requests.DropObjectsRequest;
	import org.eclipse.gmf.runtime.diagram.ui.requests.RefreshConnectionsRequest;
	import org.eclipse.gmf.runtime.diagram.ui.requests.RequestConstants;
	import org.eclipse.gmf.runtime.emf.core.util.EObjectAdapter;
	import org.eclipse.gmf.runtime.notation.Diagram;
	import org.eclipse.gmf.runtime.notation.Node;
	import org.eclipse.gmf.runtime.notation.View;
	import org.eclipse.papyrus.commands.wrappers.CommandProxyWithResult;
	import org.eclipse.papyrus.gmf.diagram.common.provider.IGraphicalTypeRegistry;
	import org.eclipse.papyrus.infra.gmfdiag.common.commands.DeferredSnapToGridCommand;
	import org.eclipse.papyrus.infra.gmfdiag.common.preferences.PreferencesConstantsHelper;
	import org.eclipse.papyrus.infra.gmfdiag.common.utils.ViewDescriptorUtil;
	import org.eclipse.papyrus.uml.diagram.common.commands.CommonDeferredCreateConnectionViewCommand;
	import org.eclipse.papyrus.uml.diagram.common.commands.SemanticAdapter;
	import org.eclipse.papyrus.uml.diagram.common.edit.part.AbstractElementBorderEditPart;
	import org.eclipse.papyrus.uml.diagram.common.edit.part.AbstractElementLabelEditPart;
	import org.eclipse.papyrus.uml.diagram.common.helper.Element2IAdaptableRegistryHelper;
	import org.eclipse.papyrus.uml.diagram.common.util.CrossReferencerUtil;
	import org.eclipse.uml2.uml.Classifier;
	import org.eclipse.uml2.uml.Element;

	/**
	* Abstract DND edit policy delegating the choice of the view to create for an EObject to a local
	* graphical type registry.
	*/
	public abstract class CommonDiagramDragDropEditPolicy extends DiagramDragDropEditPolicy {

	private Element2IAdaptableRegistryHelper myElement2IAdaptableRegistryHelper;

	/** The graphical type registry. */
	protected IGraphicalTypeRegistry registry;

	/** The list of element types that require a specific drop command. */
	private Set<String> specificDropList = null;

	/** The specified link mapping helper depending on the diagram */
	protected ILinkMappingHelper linkMappingHelper;

	/** Constructor */
	public CommonDiagramDragDropEditPolicy(ILinkMappingHelper linkMappingHelper) {
	this.linkMappingHelper = linkMappingHelper;
	}

	private Set<String> getSpecificDropList() {
	if (specificDropList == null) {
	specificDropList = getSpecificDropBehaviorTypes();
	}
	return specificDropList;
	}

	/**
	* Gets composite command adapters
	*/
	protected Element2IAdaptableRegistryHelper getElement2IAdaptableRegistryHelper() {
	if (myElement2IAdaptableRegistryHelper == null) {
	myElement2IAdaptableRegistryHelper = new Element2IAdaptableRegistryHelper();
	}
	return myElement2IAdaptableRegistryHelper;
	}

	protected abstract Set<String> getSpecificDropBehaviorTypes();

	/**
	* <pre>
	* {@inheritedDoc}.
	*
	* Overridden method to fix some exception occurring while moving affixed element (nodes or labels)
	* (https://bugs.eclipse.org/bugs/show_bug.cgi?id=350680).
	* </pre>
	*/
	@Override
	protected Command getDropCommand(ChangeBoundsRequest request) {

	Iterator<?> iter = request.getEditParts().iterator();
	EObject graphicalParentObject = ((GraphicalEditPart) getHost()).resolveSemanticElement();
	while ((graphicalParentObject != null) && (iter.hasNext())) {
	EditPart droppedEditPart = (EditPart) iter.next();
	if (droppedEditPart instanceof AbstractElementBorderEditPart) {
	return UnexecutableCommand.INSTANCE;
	}
	if (droppedEditPart instanceof AbstractElementLabelEditPart) {
	return UnexecutableCommand.INSTANCE;
	}
	}
	return super.getDropCommand(request);
	}

	/**
	* {@inheritedDoc}.
	*/
	@Override
	public Command getDropObjectsCommand(DropObjectsRequest dropRequest) {

	CompoundCommand completeDropCommand = new CompoundCommand("DropObjectsAndArrange"); //$NON-NLS-1$

	// Detect file drop
	if ((dropRequest.getObjects().size() > 0) && (dropRequest.getObjects().get(0) instanceof String)) {
	return getDropFileCommand(dropRequest);
	}

	// Create the drop command by composite drop command for each dropped elements
	CompositeCommand gmfDropCommand = new CompositeCommand("DropObjects"); //$NON-NLS-1$
	Iterator<?> iter = dropRequest.getObjects().iterator();
	while (iter.hasNext()) {
	EObject droppedObject = (EObject) iter.next();
	gmfDropCommand.add(getDropObjectCommand(dropRequest, droppedObject));
	}

	// Create the complete drop command by adding an arrange command after drop
	if (!gmfDropCommand.isEmpty()) {

	// Retrieve drop result (most probably created view but not necessarily) and update the request
	CommandResult result = gmfDropCommand.getCommandResult();
	List<?> newValues = (List<?>) result.getReturnValue();
	dropRequest.setResult(newValues);

	// Prepare refresh command
	RefreshConnectionsRequest refreshRequest = new RefreshConnectionsRequest(newValues);
	Command refreshCommand = getHost().getCommand(refreshRequest);

	// Prepare an arrange command to avoid every dropped view to appear at the same location only if newValues contains at least one node, not when you just drag a link
	boolean isOneNode = false;
	for(Object o : newValues){
	if(o instanceof Node){
	isOneNode=true;
	break;
	}
	}

	ArrangeRequest arrangeRequest = new ArrangeRequest(RequestConstants.REQ_ARRANGE_DEFERRED);
	arrangeRequest.setViewAdaptersToArrange(newValues);
	Command arrangeCommand = getHost().getCommand(arrangeRequest);

	// Update the complete drop command (drop - refresh - arrange)
	Command dropCommand = new ICommandProxy(gmfDropCommand);
	completeDropCommand.add(dropCommand.chain(refreshCommand));
	if(isOneNode){
	completeDropCommand.add(arrangeCommand);
	}

	// add snap command if required
	// 430099: [Diagram] Snap to Grid for elements dropped from the ModelExplorer is ignored
	// https://bugs.eclipse.org/bugs/show_bug.cgi?id=430099
	final Object value = dropRequest.getExtendedData().get(PreferencesConstantsHelper.SNAP_TO_GRID_CONSTANT);
	if (value instanceof Boolean && Boolean.TRUE.equals(value)) {
	DeferredSnapToGridCommand snapCommand = new DeferredSnapToGridCommand(getEditingDomain(), newValues, (IGraphicalEditPart) getHost());
	completeDropCommand.add(new ICommandProxy(snapCommand));
	}

	}

	return completeDropCommand;
	}

	protected ICommand getDropObjectCommand(DropObjectsRequest dropRequest, EObject droppedObject) {

	Point location = dropRequest.getLocation().getCopy();

	View dropTargetView = ((IGraphicalEditPart) getHost()).getNotationView();

	String droppedNodeType = registry.getNodeGraphicalType(droppedObject, dropTargetView.getType());
	String droppedEdgeType = registry.getEdgeGraphicalType(droppedObject);

	// Test if a specific drop command should be used
	if (getSpecificDropList().contains(droppedNodeType) \|\| getSpecificDropList().contains(droppedEdgeType)) {
	return getSpecificDropCommand(dropRequest, droppedObject, droppedNodeType, droppedEdgeType);
	}

	// Decide unknown type handling
	if (UNDEFINED_TYPE.equals(droppedNodeType) && UNDEFINED_TYPE.equals(droppedEdgeType)) {
	return getUnknownDropCommand(dropRequest, droppedObject);
	}

	// The dropped element is a node
	if (!UNDEFINED_TYPE.equals(droppedNodeType)) {
	return getDefaultDropNodeCommand(droppedNodeType, droppedObject, location);
	}

	// The dropped element is a edge
	if (!UNDEFINED_TYPE.equals(droppedEdgeType)) {

	Collection<?> sources = linkMappingHelper.getSource((Element) droppedObject);
	Collection<?> targets = linkMappingHelper.getTarget((Element) droppedObject);

	// Only manage binary link during drop
	if ((sources.size() > 0) && (targets.size() > 0)) {
	EObject source = (EObject) sources.toArray()[0];
	EObject target = (EObject) targets.toArray()[0];
	return getDefaultDropEdgeCommand(droppedObject, source, target, droppedEdgeType, location);
	}

	return org.eclipse.gmf.runtime.common.core.command.UnexecutableCommand.INSTANCE;
	}

	return org.eclipse.gmf.runtime.common.core.command.UnexecutableCommand.INSTANCE;
	}

	protected ICommand getDefaultDropNodeCommand(String droppedNodeType, EObject droppedObject, Point location) {
	View dropTargetView = ((IGraphicalEditPart) getHost()).getNotationView();
	EObject dropTargetElement = dropTargetView.getElement();
	// Drop restriction:
	// - no restriction when dropped on diagram
	// - require containment when dropped on any other EObject
	if ((dropTargetView instanceof Diagram) \|\| dropTargetElement.eContents().contains(droppedObject)) {
	return getDefaultDropNodeCommand(droppedNodeType, location, droppedObject);
	}

	// Allow drop for inherited elements
	if (dropTargetElement instanceof Classifier && ((Classifier) dropTargetElement).getAllAttributes().contains(droppedObject)) {
	return getDefaultDropNodeCommand(droppedNodeType, location, droppedObject);
	}
	return org.eclipse.gmf.runtime.common.core.command.UnexecutableCommand.INSTANCE;
	}

	protected ICommand getDefaultDropNodeCommand(String droppedObjectGraphicalType, Point absoluteLocation, EObject droppedObject) {

	IAdaptable elementAdapter = new EObjectAdapter(droppedObject);

	ViewDescriptor descriptor = new ViewDescriptor(elementAdapter, Node.class, droppedObjectGraphicalType, ViewUtil.APPEND, ViewDescriptorUtil.PERSISTED, getDiagramPreferencesHint());
	CreateViewRequest createViewRequest = new CreateViewRequest(descriptor);
	createViewRequest.setLocation(absoluteLocation);

	// Get view creation command for the dropped object
	Command command = getHost().getCommand(createViewRequest);

	// Use the ViewDescriptor as command result, it then can be used as an adaptable to retrieve the View
	return new CommandProxyWithResult(command, descriptor);
	}

	protected ICommand getDefaultDropEdgeCommand(EObject droppedObject, EObject source, EObject target, String droppedEdgeType, Point absoluteLocation) {

	CompositeCommand completeDropCommand = new CompositeCommand("CompleteDropEdge"); //$NON-NLS-1$

	// Find views in current diagram representing source and target
	Collection<View> sourceViews = getViews(source);
	Collection<View> targetViews = getViews(target);

	IAdaptable sourceViewAdapter = null;
	IAdaptable targetViewAdapter = null;

	// If either a source or target lacks create view for these elements
	// - using defaultDrop command (assumed to be a view creation)
	// - try to create view on host
	if (sourceViews.isEmpty() \|\| targetViews.isEmpty()) {

	CompositeCommand createEndViewsCommand = new CompositeCommand("CreateSourceTargetViews"); //$NON-NLS-1$

	View dropContainerView = ((IGraphicalEditPart) getHost()).getNotationView();
	EObject dropContainerElement = dropContainerView.getElement();

	if (sourceViews.isEmpty()) {
	if (dropContainerElement.eContents().contains(source)) {
	ICommand dropSourceCommand = getDefaultDropNodeCommand(registry.getNodeGraphicalType(source, dropContainerView.getType()), absoluteLocation.getCopy(), source);
	CompositeCommand.compose(createEndViewsCommand, dropSourceCommand);
	sourceViewAdapter = (IAdaptable) dropSourceCommand.getCommandResult().getReturnValue();
	} else {
	return org.eclipse.gmf.runtime.common.core.command.UnexecutableCommand.INSTANCE;
	}
	}

	if (targetViews.isEmpty()) {
	if (dropContainerElement.eContents().contains(target)) {
	ICommand dropTargetCommand = getDefaultDropNodeCommand(registry.getNodeGraphicalType(target, dropContainerView.getType()), absoluteLocation.getCopy(), target);
	CompositeCommand.compose(createEndViewsCommand, dropTargetCommand);
	targetViewAdapter = (IAdaptable) dropTargetCommand.getCommandResult().getReturnValue();
	} else {
	return org.eclipse.gmf.runtime.common.core.command.UnexecutableCommand.INSTANCE;
	}
	}

	CompositeCommand.compose(completeDropCommand, createEndViewsCommand);
	}

	// Create source adapter
	if (!sourceViews.isEmpty()) { // sourceViewAdapter should still be null in this case
	sourceViewAdapter = new SemanticAdapter(null, sourceViews.toArray()[0]);
	}

	// Create target adapter
	if (!targetViews.isEmpty()) { // targetViewAdapter should still be null in this case
	targetViewAdapter = new SemanticAdapter(null, targetViews.toArray()[0]);
	}

	// Create a view for the dropped link between the source and target view adapters
	IAdaptable droppedObjectAdapter = new SemanticAdapter(droppedObject, null);

	CreateConnectionViewRequest.ConnectionViewDescriptor linkdescriptor = new CreateConnectionViewRequest.ConnectionViewDescriptor(droppedObjectAdapter, droppedEdgeType, getDiagramPreferencesHint());

	CommonDeferredCreateConnectionViewCommand createConnectionViewCommand = new CommonDeferredCreateConnectionViewCommand(getEditingDomain(), droppedEdgeType, sourceViewAdapter, targetViewAdapter, getViewer(), getDiagramPreferencesHint(), linkdescriptor,
	null);
	createConnectionViewCommand.setElement(droppedObject);

	CompositeCommand.compose(completeDropCommand, createConnectionViewCommand);

	return completeDropCommand.reduce();
	}

	/**
	* <pre>
	* Sub-classes have to implement this method in order to provides specific drop command for
	* element which require a specific treatment.
	*
	* @param dropRequest current drop request
	* @param droppedEObject the dropped object
	* @param nodeType the graphical type of the dropped element (node representation)
	* @param edgeType the graphical type of the dropped element (edge representation)
	* @return the drop command
	* </pre>
	*/
	protected ICommand getSpecificDropCommand(DropObjectsRequest dropRequest, EObject droppedEObject, String nodeType, String edgeType) {
	return org.eclipse.gmf.runtime.common.core.command.UnexecutableCommand.INSTANCE;
	}

	/**
	* <pre>
	* Sub-classes have to implement this method in order to provides drop command for
	* elements that are not natively known by the diagram.
	*
	* @param dropRequest current drop request
	* @param droppedEObject the dropped object
	* @return the drop command
	* </pre>
	*/
	protected ICommand getUnknownDropCommand(DropObjectsRequest dropRequest, EObject droppedEObject) {
	return org.eclipse.gmf.runtime.common.core.command.UnexecutableCommand.INSTANCE;
	}

	protected EditPartViewer getViewer() {
	return ((IGraphicalEditPart) getHost()).getViewer();
	}

	protected TransactionalEditingDomain getEditingDomain() {
	return ((IGraphicalEditPart) getHost()).getEditingDomain();
	}

	protected PreferencesHint getDiagramPreferencesHint() {
	return ((IGraphicalEditPart) getHost()).getDiagramPreferencesHint();
	}

	/**
	* This methods looks for views representing a given EObject in the host diagram.
	*
	* @param eObject
	* the {@link EObject} to look for.
	* @return the list of {@link View} representing the eObject.
	*/
	private Set<View> getViews(EObject eObject) {
	Set<View> views = new HashSet<View>();

	// Retrieve host diagram
	View hostView = ((IGraphicalEditPart) getHost()).getNotationView();
	View hostDiagram = (hostView instanceof Diagram) ? hostView : hostView.getDiagram();

	// Retrieve all views for the eObject
	Collection<View> relatedViews = CrossReferencerUtil.getCrossReferencingViews(eObject, hostDiagram.getType());

	// Parse and select views from host diagram only
	Iterator<View> it = relatedViews.iterator();
	while (it.hasNext()) {
	View currentView = it.next();
	if (!(currentView instanceof Diagram) && (currentView.getDiagram() == hostDiagram)) {
	views.add(currentView);
	}
	}

	return views;
	}
	}