core/plugins/org.eclipse.hawk.epsilon/src/org/eclipse/hawk/epsilon/emc/pgetters/CGraphPropertyGetter.java - hawk/hawk - Git at Google

 /*******************************************************************************
  * Copyright (c) 2011-2020 The University of York.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License 2.0 which is available at
  * http://www.eclipse.org/legal/epl-2.0.
  *
  * This Source Code may also be made available under the following Secondary
  * Licenses when the conditions for such availability set forth in the Eclipse
  * Public License, v. 2.0 are satisfied: GNU General Public License, version 3.
  *
  * SPDX-License-Identifier: EPL-2.0 OR GPL-3.0
  *
  * Contributors:
  *     Konstantinos Barmpis - initial API and implementation
  *     Jonathan Co - update for Epsilon 2.0 compatibility
  ******************************************************************************/
 package org.eclipse.hawk.epsilon.emc.pgetters;

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

 import org.eclipse.epsilon.eol.exceptions.EolIllegalPropertyException;
 import org.eclipse.epsilon.eol.exceptions.EolRuntimeException;
 import org.eclipse.epsilon.eol.types.EolSequence;
 import org.eclipse.hawk.core.IModelIndexer;
 import org.eclipse.hawk.core.graph.IGraphDatabase;
 import org.eclipse.hawk.core.graph.IGraphEdge;
 import org.eclipse.hawk.core.graph.IGraphNode;
 import org.eclipse.hawk.core.util.Utils;
 import org.eclipse.hawk.epsilon.emc.EOLQueryEngine.GraphNodeWrapper;
 import org.eclipse.hawk.epsilon.emc.contextful.CEOLQueryEngine;
 import org.eclipse.hawk.graph.FileNode;
 import org.eclipse.hawk.graph.ModelElementNode;
 import org.eclipse.hawk.graph.updater.DirtyDerivedFeaturesListener;

 public class CGraphPropertyGetter extends GraphPropertyGetter {

 	private final CEOLQueryEngine engine;

 	public CGraphPropertyGetter(IGraphDatabase graph, CEOLQueryEngine m) {
 		super(graph, m);
 		engine = m;
 	}

 	@SuppressWarnings("unchecked")
 	@Override
 	public Object invoke(Object object, final String property) throws EolRuntimeException {
 		Object ret = null;
 		if (!(object instanceof GraphNodeWrapper))
 			throw new EolRuntimeException("a non GraphNodeWrapper object passed to GraphPropertyGetter!");

 		final IGraphNode node = ((GraphNodeWrapper) object).getNode();

 		// avoid using switch (in the outer-most structure) to allow partial
 		// matches and method calls in alternatives
 		if (property.equals("hawkFile")) {

 			String sep = "";
 			StringBuilder buff = new StringBuilder(32);
 			for (IGraphEdge e : node.getOutgoingWithType(ModelElementNode.EDGE_LABEL_FILE)) {
 				buff.append(sep);
 				buff.append(e.getEndNode().getProperty(IModelIndexer.IDENTIFIER_PROPERTY).toString());
 				sep = ";";

 			}
 			ret = buff.toString();

 		} else if (property.equals("hawkRepo")) {

 			String sep = "";
 			StringBuilder buff = new StringBuilder(32);
 			for (IGraphEdge e : node.getOutgoingWithType(ModelElementNode.EDGE_LABEL_FILE)) {
 				buff.append(sep);
 				buff.append(e.getEndNode().getProperty(FileNode.PROP_REPOSITORY).toString());
 				sep = ";";

 			}
 			ret = buff.toString();

 		} else if (property.equals("hawkFiles")) {

 			Set<String> files = new HashSet<>();
 			for (IGraphEdge e : node.getOutgoingWithType(ModelElementNode.EDGE_LABEL_FILE))
 				files.add(e.getEndNode().getProperty(IModelIndexer.IDENTIFIER_PROPERTY).toString());

 			ret = files;

 		} else if (property.equals("hawkRepos")) {

 			Set<String> repos = new HashSet<>();
 			for (IGraphEdge e : node.getOutgoingWithType(ModelElementNode.EDGE_LABEL_FILE))
 				repos.add(e.getEndNode().getProperty(FileNode.PROP_REPOSITORY).toString());

 			ret = repos;

 		} else if (property.startsWith(REVERSE_REFNAV_PREFIX)) {

 			List<GraphNodeWrapper> nodes = new EolSequence<GraphNodeWrapper>();
 			final String referenceName = property.substring(REVERSE_REFNAV_PREFIX.length());
 			for (IGraphEdge r : node.getIncomingWithType(referenceName)) {
 				GraphNodeWrapper n = wrapIfInScope(r.getStartNode());
 				if (n != null)
 					nodes.add(n);
 			}
 			for (IGraphEdge r : node.getIncomingWithType(ModelElementNode.DERIVED_EDGE_PREFIX + referenceName)) {
 				IGraphNode derivedNode = r.getStartNode();
 				IGraphNode elementNode = derivedNode.getIncoming().iterator().next().getStartNode();
 				GraphNodeWrapper n = wrapIfInScope(elementNode);
 				if (n != null) {
 					nodes.add(n);
 				}
 			}

 			ret = nodes;

 		} else if (property.equals("eContainer")) {

 			Iterable<IGraphEdge> inc = node.getIncoming();

 			for (IGraphEdge r : inc) {

 				if (r.getProperty(ModelElementNode.EDGE_PROPERTY_CONTAINMENT) != null) {

 					ret = wrapIfInScope(r.getStartNode());

 					break;

 				}

 			}

 			if (ret == null)
 				throw new EolRuntimeException("eContainer failed,\n" + object + "\nis not contained in current scope");

 		}

 		else if (property.equals("eContents")) {
 			ret = getContents(node);
 		}
 		else if (property.equals("eAllContents")) {
 			ret = addAllContents(node, new ArrayList<>());
 		}
 		else if (property.equals("eContainers")) {
 			for (IGraphEdge r : node.getIncoming()) {
 				if (r.getProperty(ModelElementNode.EDGE_PROPERTY_CONTAINMENT) != null) {
 					ret = wrapIfInScope(r.getStartNode());
 				}
 			}
 			if (ret == null) {
 				for (IGraphEdge r : node.getOutgoing()) {
 					if (r.getProperty(ModelElementNode.EDGE_PROPERTY_CONTAINER) != null) {
 						ret = wrapIfInScope(r.getEndNode());
 						break;
 					}
 				}
 			}

 			if (ret == null) {
 				ret = Collections.emptyList();
 			} else {
 				ret = Collections.singletonList(ret);
 			}
 		}
 		else if (property.equals("hawkIn") || property.equals("hawkOut")) {
 			final boolean isIncoming = property.equals("hawkIn");
 			final List<GraphNodeWrapper> results = new ArrayList<>();
 			final Iterable<IGraphEdge> edges = isIncoming ? node.getIncoming() : node.getOutgoing();
 			for (IGraphEdge r : edges) {
 				if (ModelElementNode.TRANSIENT_EDGE_LABELS.contains(r.getType())) {
 					continue;
 				}
 				final IGraphNode edgeNode = isIncoming ? r.getStartNode() : r.getEndNode();
 				final GraphNodeWrapper edgeNodeWrapper = wrapIfInScope(edgeNode);
 				results.add(edgeNodeWrapper);
 			}
 			ret = results;
 		}
 		else if (property.equals("hawkProxies")) {
 			// TODO perform context filtering here as well (we'd need to do our own pattern matching)
 			return new ModelElementNode(node).getProxies();
 		}
 		else if (canHaveDerivedAttr(node, property)) {

 			for (IGraphEdge r : node.getOutgoingWithType(property)) {
 				if (ret == null) {
 					final IGraphNode derivedNode = r.getEndNode();
 					ret = derivedNode.getProperty(property);
 					if (ret == null) {
 						List<GraphNodeWrapper> derivedTargets = new EolSequence<>();
 						for (IGraphEdge edge : derivedNode.getOutgoingWithType(ModelElementNode.DERIVED_EDGE_PREFIX + property)) {
 							derivedTargets.add(model.wrap(edge.getEndNode()));
 							ret = derivedTargets;
 						}
 					}

 					ret = retainScoped(ret);

 				} else {
 					throw new EolRuntimeException("WARNING: a derived property (arity 1) -- ( " + property
 							+ " ) has more than 1 links in store!");
 				}
 			}
 			if (ret == null) {
 				throw new EolRuntimeException("derived attribute lookup failed for: " + object + " # " + property);
 			} else if (ret instanceof String && ((String) ret).startsWith(DirtyDerivedFeaturesListener.NOT_YET_DERIVED_PREFIX)) {
 				// XXX IDEA: dynamically derive on the spot on access
 				System.err.println("attribute: " + property + " is NYD for node: " + node.getId());
 			}

 		}

 		else if (canHaveMixed(node, property)) {

 			ret = getCollectionForProperty(property);

 			final Collection<Object> retCollection = (Collection<Object>) ret;

 			if (node.getProperty(property) != null) {

 				final List<?> values = new Utils().asList(node.getProperty(property));
 				retCollection.addAll(values);

 			}

 			for (IGraphEdge r : node.getOutgoingWithType(property)) {
 				GraphNodeWrapper o = wrapIfInScope(r.getEndNode());
 				if (o != null)
 					retCollection.add(o);
 			}
 		}

 		else if (canHaveAttr(node, property)) {

 			if (node.getProperty(property) != null) {
 				// FIXMEdone handle collections / ordered etc
 				if (!(isMany(property)))
 					ret = node.getProperty(property);
 				else {

 					ret = getCollectionForProperty(property);

 					Object[] array = ((Object[]) node.getProperty(property));

 					for (int i = 0; i < array.length; i++)
 						((Collection<Object>) ret).add(array[i]);

 				}
 			} else
 			// return new NeoIdWrapper(0L, m);
 			{
 				// ret = "UNSET";
 				ret = null;
 				// throw new EolRuntimeException("unset property");
 			}

 		}

 		else if (canHaveRef(node, property)) {

 			GraphNodeWrapper otherNode = null;
 			Collection<Object> otherNodes = null;

 			// FIXMEdone arity etc in metamodel
 			// otherNodes = new EolBag<NeoIdWrapperDebuggable>();
 			if (isMany(property)) {
 				otherNodes = getCollectionForProperty(property);
 			}

 			for (IGraphEdge r : node.getOutgoingWithType(property)) {
 				IGraphNode n = r.getEndNode();
 				GraphNodeWrapper o = wrapIfInScope(n);
 				if (otherNodes != null) {
 					if (o != null)
 						otherNodes.add(o);
 				} else if (otherNode == null)
 					otherNode = o;
 				else
 					throw new EolRuntimeException(
 							"A relationship with arity 1 ( " + property + " ) has more than 1 links");
 			}

 			ret = otherNodes != null ? otherNodes : otherNode;

 		} else {
 			throw new EolIllegalPropertyException(object, property, null);
 		}

 		if (broadcastAccess)
 			broadcastAccess(object, property);

 		return ret;

 	}

 	private List<GraphNodeWrapper> addAllContents(IGraphNode node, List<GraphNodeWrapper> results) {
 		for (GraphNodeWrapper child : getContents(node)) {
 			results.add(child);
 			addAllContents(child.getNode(), results);
 		}
 		return results;
 	}

 	private List<GraphNodeWrapper> getContents(final IGraphNode node) {
 		final List<GraphNodeWrapper> results = new ArrayList<>();
 		Iterable<IGraphEdge> out = node.getOutgoing();
 		for (IGraphEdge r : out) {
 			if (r.getProperty(ModelElementNode.EDGE_PROPERTY_CONTAINMENT) != null) {
 				final GraphNodeWrapper endNode = wrapIfInScope(r.getEndNode());
 				if (endNode != null) {
 					results.add(endNode);
 				}
 			}
 		}
 		return results;
 	}

 	private Object retainScoped(Object ret) {

 		Collection<?> cRet = null;
 		if (ret instanceof Collection<?>)
 			cRet = (Collection<?>) ret;

 		if (cRet == null) {
 			if (ret instanceof GraphNodeWrapper)
 				ret = retainScoped((GraphNodeWrapper) ret);
 		} else {
 			Iterator<?> it = cRet.iterator();
 			while (it.hasNext()) {
 				Object r = it.next();
 				if (r instanceof GraphNodeWrapper)
 					if (retainScoped((GraphNodeWrapper) r) == null)
 						it.remove();
 			}
 		}
 		return cRet == null ? ret : cRet;
 	}

 	private Object retainScoped(GraphNodeWrapper ret) {
 		if (!engine.isTraversalScopingEnabled())
 			return ret;

 		// capture multiple file containment (ie for singleton nodes)
 		for (IGraphEdge e : graph.getNodeById(ret.getId()).getOutgoingWithType(ModelElementNode.EDGE_LABEL_FILE)) {
 			if (engine.getRawFileNodes().contains(e.getEndNode())) {
 				return ret;
 			}
 		}

 		return null;
 	}

 	private GraphNodeWrapper wrapIfInScope(IGraphNode node) {
 		if (!engine.isTraversalScopingEnabled())
 			return model.wrap(node);

 		// capture multiple file containment (ie for singleton nodes)
 		for (IGraphEdge e : node.getOutgoingWithType(ModelElementNode.EDGE_LABEL_FILE)) {
 			if (engine.getRawFileNodes().contains(e.getEndNode())) {
 				return model.wrap(node);
 			}
 		}

 		return null;
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2011-2020 The University of York.
	*
	* This program and the accompanying materials are made available under the
	* terms of the Eclipse Public License 2.0 which is available at
	* http://www.eclipse.org/legal/epl-2.0.
	*
	* This Source Code may also be made available under the following Secondary
	* Licenses when the conditions for such availability set forth in the Eclipse
	* Public License, v. 2.0 are satisfied: GNU General Public License, version 3.
	*
	* SPDX-License-Identifier: EPL-2.0 OR GPL-3.0
	*
	* Contributors:
	* Konstantinos Barmpis - initial API and implementation
	* Jonathan Co - update for Epsilon 2.0 compatibility
	******************************************************************************/
	package org.eclipse.hawk.epsilon.emc.pgetters;

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

	import org.eclipse.epsilon.eol.exceptions.EolIllegalPropertyException;
	import org.eclipse.epsilon.eol.exceptions.EolRuntimeException;
	import org.eclipse.epsilon.eol.types.EolSequence;
	import org.eclipse.hawk.core.IModelIndexer;
	import org.eclipse.hawk.core.graph.IGraphDatabase;
	import org.eclipse.hawk.core.graph.IGraphEdge;
	import org.eclipse.hawk.core.graph.IGraphNode;
	import org.eclipse.hawk.core.util.Utils;
	import org.eclipse.hawk.epsilon.emc.EOLQueryEngine.GraphNodeWrapper;
	import org.eclipse.hawk.epsilon.emc.contextful.CEOLQueryEngine;
	import org.eclipse.hawk.graph.FileNode;
	import org.eclipse.hawk.graph.ModelElementNode;
	import org.eclipse.hawk.graph.updater.DirtyDerivedFeaturesListener;

	public class CGraphPropertyGetter extends GraphPropertyGetter {

	private final CEOLQueryEngine engine;

	public CGraphPropertyGetter(IGraphDatabase graph, CEOLQueryEngine m) {
	super(graph, m);
	engine = m;
	}

	@SuppressWarnings("unchecked")
	@Override
	public Object invoke(Object object, final String property) throws EolRuntimeException {
	Object ret = null;
	if (!(object instanceof GraphNodeWrapper))
	throw new EolRuntimeException("a non GraphNodeWrapper object passed to GraphPropertyGetter!");

	final IGraphNode node = ((GraphNodeWrapper) object).getNode();

	// avoid using switch (in the outer-most structure) to allow partial
	// matches and method calls in alternatives
	if (property.equals("hawkFile")) {

	String sep = "";
	StringBuilder buff = new StringBuilder(32);
	for (IGraphEdge e : node.getOutgoingWithType(ModelElementNode.EDGE_LABEL_FILE)) {
	buff.append(sep);
	buff.append(e.getEndNode().getProperty(IModelIndexer.IDENTIFIER_PROPERTY).toString());
	sep = ";";

	}
	ret = buff.toString();

	} else if (property.equals("hawkRepo")) {

	String sep = "";
	StringBuilder buff = new StringBuilder(32);
	for (IGraphEdge e : node.getOutgoingWithType(ModelElementNode.EDGE_LABEL_FILE)) {
	buff.append(sep);
	buff.append(e.getEndNode().getProperty(FileNode.PROP_REPOSITORY).toString());
	sep = ";";

	}
	ret = buff.toString();

	} else if (property.equals("hawkFiles")) {

	Set<String> files = new HashSet<>();
	for (IGraphEdge e : node.getOutgoingWithType(ModelElementNode.EDGE_LABEL_FILE))
	files.add(e.getEndNode().getProperty(IModelIndexer.IDENTIFIER_PROPERTY).toString());

	ret = files;

	} else if (property.equals("hawkRepos")) {

	Set<String> repos = new HashSet<>();
	for (IGraphEdge e : node.getOutgoingWithType(ModelElementNode.EDGE_LABEL_FILE))
	repos.add(e.getEndNode().getProperty(FileNode.PROP_REPOSITORY).toString());

	ret = repos;

	} else if (property.startsWith(REVERSE_REFNAV_PREFIX)) {

	List<GraphNodeWrapper> nodes = new EolSequence<GraphNodeWrapper>();
	final String referenceName = property.substring(REVERSE_REFNAV_PREFIX.length());
	for (IGraphEdge r : node.getIncomingWithType(referenceName)) {
	GraphNodeWrapper n = wrapIfInScope(r.getStartNode());
	if (n != null)
	nodes.add(n);
	}
	for (IGraphEdge r : node.getIncomingWithType(ModelElementNode.DERIVED_EDGE_PREFIX + referenceName)) {
	IGraphNode derivedNode = r.getStartNode();
	IGraphNode elementNode = derivedNode.getIncoming().iterator().next().getStartNode();
	GraphNodeWrapper n = wrapIfInScope(elementNode);
	if (n != null) {
	nodes.add(n);
	}
	}

	ret = nodes;

	} else if (property.equals("eContainer")) {

	Iterable<IGraphEdge> inc = node.getIncoming();

	for (IGraphEdge r : inc) {

	if (r.getProperty(ModelElementNode.EDGE_PROPERTY_CONTAINMENT) != null) {

	ret = wrapIfInScope(r.getStartNode());

	break;

	}

	}

	if (ret == null)
	throw new EolRuntimeException("eContainer failed,\n" + object + "\nis not contained in current scope");

	}

	else if (property.equals("eContents")) {
	ret = getContents(node);
	}
	else if (property.equals("eAllContents")) {
	ret = addAllContents(node, new ArrayList<>());
	}
	else if (property.equals("eContainers")) {
	for (IGraphEdge r : node.getIncoming()) {
	if (r.getProperty(ModelElementNode.EDGE_PROPERTY_CONTAINMENT) != null) {
	ret = wrapIfInScope(r.getStartNode());
	}
	}
	if (ret == null) {
	for (IGraphEdge r : node.getOutgoing()) {
	if (r.getProperty(ModelElementNode.EDGE_PROPERTY_CONTAINER) != null) {
	ret = wrapIfInScope(r.getEndNode());
	break;
	}
	}
	}

	if (ret == null) {
	ret = Collections.emptyList();
	} else {
	ret = Collections.singletonList(ret);
	}
	}
	else if (property.equals("hawkIn") \|\| property.equals("hawkOut")) {
	final boolean isIncoming = property.equals("hawkIn");
	final List<GraphNodeWrapper> results = new ArrayList<>();
	final Iterable<IGraphEdge> edges = isIncoming ? node.getIncoming() : node.getOutgoing();
	for (IGraphEdge r : edges) {
	if (ModelElementNode.TRANSIENT_EDGE_LABELS.contains(r.getType())) {
	continue;
	}
	final IGraphNode edgeNode = isIncoming ? r.getStartNode() : r.getEndNode();
	final GraphNodeWrapper edgeNodeWrapper = wrapIfInScope(edgeNode);
	results.add(edgeNodeWrapper);
	}
	ret = results;
	}
	else if (property.equals("hawkProxies")) {
	// TODO perform context filtering here as well (we'd need to do our own pattern matching)
	return new ModelElementNode(node).getProxies();
	}
	else if (canHaveDerivedAttr(node, property)) {

	for (IGraphEdge r : node.getOutgoingWithType(property)) {
	if (ret == null) {
	final IGraphNode derivedNode = r.getEndNode();
	ret = derivedNode.getProperty(property);
	if (ret == null) {
	List<GraphNodeWrapper> derivedTargets = new EolSequence<>();
	for (IGraphEdge edge : derivedNode.getOutgoingWithType(ModelElementNode.DERIVED_EDGE_PREFIX + property)) {
	derivedTargets.add(model.wrap(edge.getEndNode()));
	ret = derivedTargets;
	}
	}

	ret = retainScoped(ret);

	} else {
	throw new EolRuntimeException("WARNING: a derived property (arity 1) -- ( " + property
	+ " ) has more than 1 links in store!");
	}
	}
	if (ret == null) {
	throw new EolRuntimeException("derived attribute lookup failed for: " + object + " # " + property);
	} else if (ret instanceof String && ((String) ret).startsWith(DirtyDerivedFeaturesListener.NOT_YET_DERIVED_PREFIX)) {
	// XXX IDEA: dynamically derive on the spot on access
	System.err.println("attribute: " + property + " is NYD for node: " + node.getId());
	}

	}

	else if (canHaveMixed(node, property)) {

	ret = getCollectionForProperty(property);

	final Collection<Object> retCollection = (Collection<Object>) ret;

	if (node.getProperty(property) != null) {

	final List<?> values = new Utils().asList(node.getProperty(property));
	retCollection.addAll(values);

	}

	for (IGraphEdge r : node.getOutgoingWithType(property)) {
	GraphNodeWrapper o = wrapIfInScope(r.getEndNode());
	if (o != null)
	retCollection.add(o);
	}
	}

	else if (canHaveAttr(node, property)) {

	if (node.getProperty(property) != null) {
	// FIXMEdone handle collections / ordered etc
	if (!(isMany(property)))
	ret = node.getProperty(property);
	else {

	ret = getCollectionForProperty(property);

	Object[] array = ((Object[]) node.getProperty(property));

	for (int i = 0; i < array.length; i++)
	((Collection<Object>) ret).add(array[i]);

	}
	} else
	// return new NeoIdWrapper(0L, m);
	{
	// ret = "UNSET";
	ret = null;
	// throw new EolRuntimeException("unset property");
	}

	}

	else if (canHaveRef(node, property)) {

	GraphNodeWrapper otherNode = null;
	Collection<Object> otherNodes = null;

	// FIXMEdone arity etc in metamodel
	// otherNodes = new EolBag<NeoIdWrapperDebuggable>();
	if (isMany(property)) {
	otherNodes = getCollectionForProperty(property);
	}

	for (IGraphEdge r : node.getOutgoingWithType(property)) {
	IGraphNode n = r.getEndNode();
	GraphNodeWrapper o = wrapIfInScope(n);
	if (otherNodes != null) {
	if (o != null)
	otherNodes.add(o);
	} else if (otherNode == null)
	otherNode = o;
	else
	throw new EolRuntimeException(
	"A relationship with arity 1 ( " + property + " ) has more than 1 links");
	}

	ret = otherNodes != null ? otherNodes : otherNode;

	} else {
	throw new EolIllegalPropertyException(object, property, null);
	}

	if (broadcastAccess)
	broadcastAccess(object, property);

	return ret;

	}

	private List<GraphNodeWrapper> addAllContents(IGraphNode node, List<GraphNodeWrapper> results) {
	for (GraphNodeWrapper child : getContents(node)) {
	results.add(child);
	addAllContents(child.getNode(), results);
	}
	return results;
	}

	private List<GraphNodeWrapper> getContents(final IGraphNode node) {
	final List<GraphNodeWrapper> results = new ArrayList<>();
	Iterable<IGraphEdge> out = node.getOutgoing();
	for (IGraphEdge r : out) {
	if (r.getProperty(ModelElementNode.EDGE_PROPERTY_CONTAINMENT) != null) {
	final GraphNodeWrapper endNode = wrapIfInScope(r.getEndNode());
	if (endNode != null) {
	results.add(endNode);
	}
	}
	}
	return results;
	}

	private Object retainScoped(Object ret) {

	Collection<?> cRet = null;
	if (ret instanceof Collection<?>)
	cRet = (Collection<?>) ret;

	if (cRet == null) {
	if (ret instanceof GraphNodeWrapper)
	ret = retainScoped((GraphNodeWrapper) ret);
	} else {
	Iterator<?> it = cRet.iterator();
	while (it.hasNext()) {
	Object r = it.next();
	if (r instanceof GraphNodeWrapper)
	if (retainScoped((GraphNodeWrapper) r) == null)
	it.remove();
	}
	}
	return cRet == null ? ret : cRet;
	}

	private Object retainScoped(GraphNodeWrapper ret) {
	if (!engine.isTraversalScopingEnabled())
	return ret;

	// capture multiple file containment (ie for singleton nodes)
	for (IGraphEdge e : graph.getNodeById(ret.getId()).getOutgoingWithType(ModelElementNode.EDGE_LABEL_FILE)) {
	if (engine.getRawFileNodes().contains(e.getEndNode())) {
	return ret;
	}
	}

	return null;
	}

	private GraphNodeWrapper wrapIfInScope(IGraphNode node) {
	if (!engine.isTraversalScopingEnabled())
	return model.wrap(node);

	// capture multiple file containment (ie for singleton nodes)
	for (IGraphEdge e : node.getOutgoingWithType(ModelElementNode.EDGE_LABEL_FILE)) {
	if (engine.getRawFileNodes().contains(e.getEndNode())) {
	return model.wrap(node);
	}
	}

	return null;
	}
	}