[Code Completion] Compute proposals for two different contexts https://bugs.eclipse.org/bugs/show_bug.cgi?id=263770

11 files changed, 248 insertions, 461 deletions

diff --git a/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/IProposalProvider.java b/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/IProposalProvider.java
index 05ba96d..1b7691f 100644
--- a/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/IProposalProvider.java
+++ b/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/IProposalProvider.java
@@ -1,3 +1,11 @@
+/*******************************************************************************
+ * Copyright (c) 2008 Michael Clay 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
+ *
+ *******************************************************************************/
 package org.eclipse.xtext.ui.common.editor.contentassist;
 
 import java.util.List;
@@ -10,20 +18,16 @@ import org.eclipse.xtext.Keyword;
 import org.eclipse.xtext.RuleCall;
 
 /**
- * 
  * @author Sven Efftinge - Initial contribution and API
  * @author Michael Clay
  */
 public interface IProposalProvider {
-
 	/**
 	 * Is invoked by the framework if (with respect to the grammar) it is
 	 * possible that the keyword passed as first parameter can occur next up.
 	 * 
-	 * @param keyword
-	 *            the <code>Keyword</code> to be completed
-	 * @param contentAssistContext
-	 *            the current context of the content assist
+	 * @param keyword the <code>Keyword</code> to be completed
+	 * @param contentAssistContext the current context of the content assist
 	 * @return a list of matching {@link ICompletionProposal}
 	 */
 	List<? extends ICompletionProposal> completeKeyword(Keyword keyword, IContentAssistContext contentAssistContext);
@@ -32,10 +36,8 @@ public interface IProposalProvider {
 	 * Is invoked by the framework if (with respect to the grammar) it is
 	 * possible that the rule call passed as first parameter can occur next up.
 	 * 
-	 * @param ruleCall
-	 *            the <code>RuleCall</code> to be completed
-	 * @param contentAssistContext
-	 *            the current context of the content assist
+	 * @param ruleCall the <code>RuleCall</code> to be completed
+	 * @param contentAssistContext the current context of the content assist
 	 * @return a list of matching {@link ICompletionProposal}
 	 */
 	List<? extends ICompletionProposal> completeRuleCall(RuleCall ruleCall, IContentAssistContext contentAssistContext);
@@ -44,10 +46,8 @@ public interface IProposalProvider {
 	 * Is invoked by the framework if (with respect to the grammar) it is
 	 * possible that the assignment passed as first parameter can occur next up.
 	 * 
-	 * @param assignment
-	 *            the <code>Assignment</code> to be completed
-	 * @param contentAssistContext
-	 *            the current context of the content assist
+	 * @param assignment the <code>Assignment</code> to be completed
+	 * @param contentAssistContext the current context of the content assist
 	 * @return a list of matching {@link ICompletionProposal}
 	 */
 	List<? extends ICompletionProposal> completeAssignment(Assignment assignment, IContentAssistContext contentAssistContext);
@@ -56,10 +56,8 @@ public interface IProposalProvider {
 	 * Returns the context type that can handle template insertion at the given
 	 * region in the viewer's document.
 	 * 
-	 * @param keyword
-	 *            the <code>Keyword</code> to be completed
-	 * @param contentAssistContext
-	 *            the current context of the content assist
+	 * @param keyword the <code>Keyword</code> to be completed
+	 * @param contentAssistContext the current context of the content assist
 	 * @return the context type that can handle template expansion for the given
 	 *         location, or <code>null</code> if none exists
 	 */
@@ -69,37 +67,40 @@ public interface IProposalProvider {
 	 * Returns the context type that can handle template insertion at the given
 	 * region in the viewer's document.
 	 * 
-	 * @param ruleCall
-	 *            the <code>RuleCall</code>
-	 * @param contentAssistContext
-	 *            the current context of the content assist
+	 * @param ruleCall the <code>RuleCall</code>
+	 * @param contentAssistContext the current context of the content assist
 	 * @return the context type that can handle template expansion for the given
 	 *         location, or <code>null</code> if none exists
 	 */
 	TemplateContextType getTemplateContextType(RuleCall ruleCall, IContentAssistContext contentAssistContext);
-
+	
 	/**
 	 * Returns the templates valid for the context type specified by
 	 * <code>contextTypeId</code>.
 	 * 
-	 * @param contextTypeId
-	 *            the context type id
+	 * @param contextTypeId the context type id
 	 * @return the templates valid for this context type id
 	 */
 	Template[] getTemplates(String contextTypeId);
-
+	
 	/**
-	 * Used to filter and sort a list of completion proposals. This method is
-	 * invoked by the framework after all possible completions have been
-	 * collected.
+	 * Used to filter the given list of completion proposals. 
+	 * <p/>
+	 * This method is after all possible completions and templates have been collected.
 	 * 
-	 * @param completionProposalList
-	 *            matching {@link ICompletionProposal} to sort and filter
-	 * @param contentAssistContext
-	 *            the current context of the content assist
-	 * @return the sorted and filtered <code>ICompletionProposal</code> list.
+	 * @param completionProposalList the collected list of {@link ICompletionProposal} to filter
+	 * @param contentAssistContext the current context of the content assist
+	 * @return the filtered <code>ICompletionProposal</code> list.
 	 */
-	List<? extends ICompletionProposal> sortAndFilter(List<? extends ICompletionProposal> completionProposalList,
-			IContentAssistContext contentAssistContext);
-
+	List<? extends ICompletionProposal> filter(List<ICompletionProposal> completionProposalList,IContentAssistContext contentAssistContext);
+	
+	/**
+	 * Used to sort the given list of completion proposals. 
+	 * <p/>
+	 * This method is after all possible completions and templates have been collected and filtered.
+	 * 
+	 * @param completionProposalList the collected list of {@link ICompletionProposal} to sort
+	 * @return the sorted <code>ICompletionProposal</code> list.
+	 */
+	List<? extends ICompletionProposal> sort(List<ICompletionProposal> completionProposalList);
 }
diff --git a/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/AbstractJavaProposalProvider.java b/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/AbstractJavaProposalProvider.java
index c28854d..5b01ea7 100644
--- a/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/AbstractJavaProposalProvider.java
+++ b/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/AbstractJavaProposalProvider.java
@@ -45,16 +45,13 @@ import com.google.inject.Inject;
  * @author Jan Köhnlein - Initial contribution and API
  */
 public abstract class AbstractJavaProposalProvider implements IProposalProvider {
-
 	// constants
 	// protected static final String LEXER_RULE_ID = "ID";
 	protected static final String LEXER_RULE_INT = "INT";
 	protected static final String LEXER_RULE_STRING = "STRING";
 
 	// logger available to subclasses
-	protected final static Logger logger = Logger
-			.getLogger(IProposalProvider.class);
-
+	protected final static Logger logger = Logger.getLogger(IProposalProvider.class);
 	@Inject
 	protected IScopeProvider scopeProvider;
 
@@ -63,7 +60,6 @@ public abstract class AbstractJavaProposalProvider implements IProposalProvider
 	protected AbstractJavaProposalProvider() {
 		invoker = new JavaReflectiveMethodInvoker(this);
 	}
-
 	/**
 	 * @see org.eclipse.xtext.ui.common.editor.contentassist.IProposalProvider#completeKeyword(Keyword,
 	 *      IContentAssistContext)
@@ -71,10 +67,8 @@ public abstract class AbstractJavaProposalProvider implements IProposalProvider
 	public List<? extends ICompletionProposal> completeKeyword(Keyword keyword,
 			IContentAssistContext contentAssistContext) {
 		if (logger.isDebugEnabled()) {
-			logger.debug("completeKeyword '" + keyword.getValue()
-					+ "' for model '" + contentAssistContext.getModel()
-					+ "' and prefix '"
-					+ contentAssistContext.getMatchString().trim() + "'");
+			logger.debug("completeKeyword '" + keyword.getValue()+ "' for model '" + contentAssistContext.getModel()
+				+ "' and prefix '"+ contentAssistContext.getMatchString().trim() + "'");
 		}
 		return Collections.singletonList(createCompletionProposal(keyword,
 				keyword.getValue(), contentAssistContext));
@@ -87,41 +81,21 @@ public abstract class AbstractJavaProposalProvider implements IProposalProvider
 	public List<? extends ICompletionProposal> completeRuleCall(
 			RuleCall ruleCall, IContentAssistContext contentAssistContext) {
 		if (logger.isDebugEnabled()) {
-			logger
-					.debug("completeRuleCall '"
-							+ ruleCall.getRule().getName()
-							+ "' cardinality '"
-							+ ruleCall.getCardinality()
-							+ "' for model '"
-							+ contentAssistContext.getModel()
-							+ "' and prefix '"
-							+ contentAssistContext.getMatchString().trim()
-									.trim() + "'");
+			logger.debug("completeRuleCall '"+ ruleCall.getRule().getName()+ "' cardinality '"
+				+ ruleCall.getCardinality()+ "' for model '"+ contentAssistContext.getModel()
+				+ "' and prefix '"+ contentAssistContext.getMatchString().trim().trim() + "'");
 		}
-
 		AbstractRule calledRule = ruleCall.getRule();
-
 		if (calledRule instanceof TerminalRule) {
-			return completeTerminalRuleRuleCall((TerminalRule) calledRule, ruleCall,
-					contentAssistContext);
+			return completeTerminalRuleRuleCall((TerminalRule) calledRule, ruleCall,contentAssistContext);
 		} else if (calledRule.getType() != null) {
-
 			TypeRef typeRef = calledRule.getType();
-
-			return invokeMethod(
-					"complete"
-							+ Strings.toFirstUpper(typeRef.getMetamodel()
-									.getAlias()) + "_"
+			return invokeMethod("complete"+ Strings.toFirstUpper(typeRef.getMetamodel().getAlias()) + "_"
 							+ Strings.toFirstUpper(typeRef.getClassifier().getName()),
-					Arrays
-							.<Class<?>> asList(
-									RuleCall.class,
-									contentAssistContext.getModel() == null ? EObject.class
-											: contentAssistContext.getModel()
-													.getClass(),
-									IContentAssistContext.class), Arrays
-							.asList(ruleCall, contentAssistContext.getModel(),
-									contentAssistContext));
+							Arrays.<Class<?>> asList(RuleCall.class,contentAssistContext.getModel() == null ? 
+							EObject.class : contentAssistContext.getModel().getClass(),
+							IContentAssistContext.class), Arrays.asList(ruleCall,
+									contentAssistContext.getModel(),contentAssistContext));
 		}
 		return Collections.emptyList();
 	}
@@ -134,12 +108,9 @@ public abstract class AbstractJavaProposalProvider implements IProposalProvider
 			Assignment assignment, IContentAssistContext contentAssistContext) {
 		ParserRule parserRule = GrammarUtil.containingParserRule(assignment);
 		// TODO : Better call completeRuleCall ?
-		return invokeMethod("complete"
-				+ Strings.toFirstUpper(parserRule.getName()) + "_"
-				+ Strings.toFirstUpper(assignment.getFeature()), Arrays
-				.<Class<?>> asList(Assignment.class,
-						IContentAssistContext.class), Arrays.asList(assignment,
-				contentAssistContext));
+		return invokeMethod("complete"+ Strings.toFirstUpper(parserRule.getName()) + "_"+ 
+					Strings.toFirstUpper(assignment.getFeature()), Arrays.<Class<?>> asList(Assignment.class,
+						IContentAssistContext.class), Arrays.asList(assignment,contentAssistContext));
 	}
 
 	/**
@@ -149,20 +120,13 @@ public abstract class AbstractJavaProposalProvider implements IProposalProvider
 	protected ICompletionProposal createCompletionProposal(
 			AbstractElement abstractElement, String displayString,
 			IContentAssistContext contentAssistContext) {
-		return new XtextCompletionProposal(abstractElement, displayString,
-				contentAssistContext);
+		return new XtextCompletionProposal(abstractElement, displayString,contentAssistContext);
 	}
 
 	@SuppressWarnings("unchecked")
-	protected List<? extends ICompletionProposal> invokeMethod(
-			String methodName, List<Class<?>> parameterTypes,
+	protected List<? extends ICompletionProposal> invokeMethod(String methodName, List<Class<?>> parameterTypes,
 			List<?> parameterValues) {
-		try {
-			return (List<? extends ICompletionProposal>) invoker.invoke(
-					methodName, parameterTypes, parameterValues);
-		} catch (NullPointerException exc) {
-			return null;
-		}
+		return (List<? extends ICompletionProposal>) invoker.invoke(methodName, parameterTypes, parameterValues);
 	}
 
 	/**
@@ -231,23 +195,21 @@ public abstract class AbstractJavaProposalProvider implements IProposalProvider
 	 */
 	protected abstract String getDefaultImageFilePath();
 
-	/**
-	 * Concrete subclasses can override this for custom sort and filter
-	 * behavior. Called right after all completion proposals have been
-	 * collected.
-	 *
-	 * The default behavior of this implementation is to filter duplicates and
-	 * to trim matching <code>ICompletionProposal#displayString</code> with
-	 * matching prefix values.
-	 *
-	 * @see #sortAndFilter(List, EObject, String, IDocument, int, AbstractNode,
-	 *      LeafNode)
+	/*
+	 * (non-Javadoc)
+	 * @see org.eclipse.xtext.ui.common.editor.contentassist.IProposalProvider#filter(java.util.List, org.eclipse.xtext.ui.common.editor.contentassist.IContentAssistContext)
 	 */
-	public List<? extends ICompletionProposal> sortAndFilter(
-			List<? extends ICompletionProposal> completionProposalList,
+	public List<? extends ICompletionProposal> filter(List<ICompletionProposal> completionProposalList,
 			IContentAssistContext contentAssistContext) {
-		return ProposalFilterSorterUtil.sortAndFilter(completionProposalList,
-				contentAssistContext);
+		return ProposalFilterSorterUtil.filter(completionProposalList,contentAssistContext);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.eclipse.xtext.ui.common.editor.contentassist.IProposalProvider#sort(java.util.List)
+	 */
+	public List<? extends ICompletionProposal> sort(List<ICompletionProposal> completionProposalList) {
+		return ProposalFilterSorterUtil.sort(completionProposalList);
 	}
 
 	/**
@@ -259,29 +221,21 @@ public abstract class AbstractJavaProposalProvider implements IProposalProvider
 	 *         assignment
 	 */
 	protected List<? extends ICompletionProposal> lookupCrossReference(
-			CrossReference crossReference,
-			IContentAssistContext contentAssistContext) {
-
+			CrossReference crossReference,IContentAssistContext contentAssistContext) {
 		List<ICompletionProposal> completionProposalList = new ArrayList<ICompletionProposal>();
-
 		if (scopeProvider != null) {
 			ParserRule containingParserRule = GrammarUtil
 					.containingParserRule(crossReference);
 			if (!GrammarUtil.isDatatypeRule(containingParserRule)) {
-				final EClass eClass = (EClass) containingParserRule.getType().getClassifier();
-				final EReference ref = GrammarUtil.getReference(crossReference,
-						eClass);
-				final String trimmedPrefix = contentAssistContext
-						.getMatchString().trim();
-				final Iterable<IScopedElement> candidates = scopeProvider
-						.getScope(contentAssistContext.getModel(), ref)
+				EClass eClass = (EClass) containingParserRule.getType().getClassifier();
+				EReference ref = GrammarUtil.getReference(crossReference,eClass);
+				String trimmedPrefix = contentAssistContext.getMatchString().trim();
+				Iterable<IScopedElement> candidates = scopeProvider.getScope(contentAssistContext.getModel(), ref)
 						.getAllContents();
 				for (IScopedElement candidate : candidates) {
-					if (candidate.name() != null
-							&& isCandidateMatchingPrefix(contentAssistContext
+					if (candidate.name() != null && isCandidateMatchingPrefix(contentAssistContext
 									.getModel(), ref, candidate, trimmedPrefix)) {
-						completionProposalList.add(createCompletionProposal(
-								crossReference, candidate.name(),
+						completionProposalList.add(createCompletionProposal(crossReference, candidate.name(),
 								contentAssistContext));
 					}
 				}
@@ -294,9 +248,7 @@ public abstract class AbstractJavaProposalProvider implements IProposalProvider
 	protected boolean isCandidateMatchingPrefix(EObject model, EReference ref,
 			IScopedElement candidate, String prefix) {
 		if (candidate.name() == null)
-			throw new IllegalArgumentException(
-					"unnamed candidates may not be proposed");
-		return candidate.name().regionMatches(true, 0, prefix, 0,
-				prefix.length());
+			throw new IllegalArgumentException("unnamed candidates may not be proposed");
+		return candidate.name().regionMatches(true, 0, prefix, 0,prefix.length());
 	}
 }
diff --git a/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/DefaultContentAssistCalculator.java b/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/DefaultContentAssistCalculator.java
index 42624a5..3887552 100644
--- a/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/DefaultContentAssistCalculator.java
+++ b/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/DefaultContentAssistCalculator.java
@@ -11,35 +11,27 @@ package org.eclipse.xtext.ui.common.editor.contentassist.impl;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Iterator;
-import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
 
 import org.eclipse.emf.common.util.EList;
 import org.eclipse.emf.ecore.EObject;
-import org.eclipse.emf.ecore.EReference;
 import org.eclipse.xtext.AbstractElement;
 import org.eclipse.xtext.AbstractRule;
 import org.eclipse.xtext.Alternatives;
 import org.eclipse.xtext.Assignment;
 import org.eclipse.xtext.CrossReference;
-import org.eclipse.xtext.EcoreUtil2;
 import org.eclipse.xtext.GrammarUtil;
 import org.eclipse.xtext.Group;
 import org.eclipse.xtext.Keyword;
 import org.eclipse.xtext.ParserRule;
 import org.eclipse.xtext.RuleCall;
-import org.eclipse.xtext.crossref.ILinkingService;
-import org.eclipse.xtext.crossref.impl.IllegalNodeException;
 import org.eclipse.xtext.parsetree.AbstractNode;
-import org.eclipse.xtext.parsetree.NodeUtil;
 import org.eclipse.xtext.parsetree.ParseTreeUtil;
 import org.eclipse.xtext.ui.common.editor.contentassist.IContentAssistCalculator;
 import org.eclipse.xtext.ui.common.editor.contentassist.IContentAssistContext;
 import org.eclipse.xtext.util.XtextSwitch;
 
-import com.google.inject.Inject;
-
 /**
  * Provides a default implementation of interface {@link IContentAssistContext} designed as <b>Switch</b> over the
  * Xtext ecore inheritance hierarchy to calculate and resolve (or flatten) 'container' level elements like
@@ -53,59 +45,19 @@ import com.google.inject.Inject;
  */
 public class DefaultContentAssistCalculator extends XtextSwitch<List<AbstractElement>> implements IContentAssistCalculator {
 
-	@Inject
-	private ILinkingService linkingService;
-
 	public List<AbstractElement> computeProposalElements(IContentAssistContext contentAssistContext) {
-
 		List<AbstractElement> computedElementList = new ArrayList<AbstractElement>();
-
-		Set<AbstractElement> nextValidElementSet = new LinkedHashSet<AbstractElement>();
-
 		AbstractNode referenceNode=contentAssistContext.getReferenceNode();
-		/**
-		 * in case of a cross reference which isn't linked properly we evaluate or
-		 * propose it again
-		 */
-		if (referenceNode != null && referenceNode.getGrammarElement() instanceof CrossReference && !isLinked(referenceNode)) {
-			nextValidElementSet.add(getAbstractElement(referenceNode));
-			nextValidElementSet.addAll(ParseTreeUtil.getElementSetValidFromOffset(contentAssistContext.getRootNode(),
-					referenceNode, contentAssistContext.getOffSet()));
-		} else if (referenceNode == contentAssistContext.getNode()) {
-			if (referenceNode == null)
-				throw new NullPointerException("Unexpected: referenceNode is null.");
-			/**
-			 * in case of 'at-the-end' of the previous,completed element we evaluate
-			 * it again for 'right-to-left-backtracking' cases (e.g. for keyword
-			 * 'kind' kind>|< |=cursorpos)
-			 */
-			Assignment containingAssignment = GrammarUtil.containingAssignment(referenceNode.getGrammarElement());
-
-			if (referenceNode.getGrammarElement() instanceof RuleCall && containingAssignment != null) {
-				nextValidElementSet.add(containingAssignment);
-				nextValidElementSet.addAll(ParseTreeUtil.getElementSetValidFromOffset(contentAssistContext
-						.getRootNode(), referenceNode, contentAssistContext.getOffSet()));
-			}
-			else {
-				nextValidElementSet = ParseTreeUtil.getElementSetValidFromOffset(contentAssistContext.getRootNode(),
-						referenceNode, contentAssistContext.getOffSet());
-				nextValidElementSet.add(getAbstractElement(referenceNode));
-			}
-		}
-		else if (referenceNode != null){
-			nextValidElementSet = ParseTreeUtil.getElementSetValidFromOffset(contentAssistContext.getRootNode(),
-					referenceNode, contentAssistContext.getOffSet());
-		}
-
+		Set<AbstractElement> nextValidElementSet = ParseTreeUtil.getElementSetValidFromOffset(
+				contentAssistContext.getRootNode(),referenceNode, contentAssistContext.getOffSet());
+		
 		for (Iterator<AbstractElement> iterator = nextValidElementSet.iterator(); iterator.hasNext();) {
 			AbstractElement abstractElement = iterator.next();
 			computedElementList.addAll(doSwitch(abstractElement));
 		}
-
 		return computedElementList;
 	}
 
-
 	@Override
 	public List<AbstractElement> caseAlternatives(Alternatives alternatives) {
 		List<AbstractElement> elementList = new ArrayList<AbstractElement>();
@@ -144,12 +96,8 @@ public class DefaultContentAssistCalculator extends XtextSwitch<List<AbstractEle
 
 	@Override
 	public List<AbstractElement> caseRuleCall(RuleCall ruleCall) {
-		List<AbstractElement> elementList = new ArrayList<AbstractElement>();
-
-		elementList.add(ruleCall);
-
+		List<AbstractElement> elementList = new ArrayList<AbstractElement>(Collections.singleton(ruleCall));
 		AbstractRule abstractRule = ruleCall.getRule();
-
 		if (abstractRule instanceof ParserRule) {
 			addWithNullCheck(elementList, doSwitch(((ParserRule) abstractRule).getAlternatives()));
 		}
@@ -172,35 +120,11 @@ public class DefaultContentAssistCalculator extends XtextSwitch<List<AbstractEle
 		}
 	}
 
-	private AbstractElement getAbstractElement(AbstractNode lastCompleteNode) {
-		return (AbstractElement) (lastCompleteNode.getGrammarElement() instanceof ParserRule ?
-				((ParserRule)lastCompleteNode.getGrammarElement()).getAlternatives(): lastCompleteNode.getGrammarElement());
-	}
-
-	private boolean isLinked(AbstractNode lastCompleteNode) {
-		EObject semanticModel = NodeUtil.getNearestSemanticObject(lastCompleteNode);
-		CrossReference crossReference = (CrossReference) lastCompleteNode.getGrammarElement();
-		EReference eReference = GrammarUtil.getReference(crossReference, semanticModel.eClass());
-
-		List<EObject> referencedObjects = EcoreUtil2.getAllReferencedObjects(semanticModel, eReference);
-
-		if (referencedObjects.isEmpty())
-			return false;
-		try {
-			List<EObject> linkCandidates = linkingService.getLinkedObjects(semanticModel, eReference, lastCompleteNode);
-			return !linkCandidates.isEmpty() && referencedObjects.containsAll(linkCandidates);
-		} catch( IllegalNodeException ex) {
-			return false;
-		}
-	}
-
 	private boolean isOptional(AbstractElement groupElement) {
 		boolean isOptional = true;
-
 		if ((groupElement instanceof Group || groupElement instanceof Alternatives) && !GrammarUtil.isOptionalCardinality(groupElement)) {
-
-			EList<AbstractElement> abstractTokens = groupElement instanceof Group ? ((Group) groupElement).getTokens() : ((Alternatives) groupElement).getGroups();
-
+			EList<AbstractElement> abstractTokens = groupElement instanceof Group ? 
+					((Group) groupElement).getTokens() : ((Alternatives) groupElement).getGroups();
 			for (Iterator<AbstractElement> iterator = abstractTokens.iterator(); isOptional && iterator.hasNext();) {
 				AbstractElement abstractElement = iterator.next();
 				isOptional = isOptional(abstractElement);
@@ -211,6 +135,4 @@ public class DefaultContentAssistCalculator extends XtextSwitch<List<AbstractEle
 		}
 		return isOptional;
 	}
-
-
 }
diff --git a/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/DefaultContentAssistProcessor.java b/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/DefaultContentAssistProcessor.java
index a820d9f..a20759e 100644
--- a/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/DefaultContentAssistProcessor.java
+++ b/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/DefaultContentAssistProcessor.java
@@ -24,16 +24,16 @@ import org.eclipse.jface.text.contentassist.IContentAssistProcessor;
 import org.eclipse.jface.text.contentassist.IContextInformation;
 import org.eclipse.jface.text.contentassist.IContextInformationValidator;
 import org.eclipse.jface.text.templates.TemplateContextType;
-import org.eclipse.swt.custom.StyledText;
 import org.eclipse.xtext.AbstractElement;
 import org.eclipse.xtext.Assignment;
+import org.eclipse.xtext.CrossReference;
 import org.eclipse.xtext.Keyword;
 import org.eclipse.xtext.RuleCall;
+import org.eclipse.xtext.TerminalRule;
 import org.eclipse.xtext.XtextPackage;
 import org.eclipse.xtext.parser.IParseResult;
 import org.eclipse.xtext.parsetree.AbstractNode;
 import org.eclipse.xtext.parsetree.CompositeNode;
-import org.eclipse.xtext.parsetree.LeafNode;
 import org.eclipse.xtext.parsetree.NodeUtil;
 import org.eclipse.xtext.parsetree.ParseTreeUtil;
 import org.eclipse.xtext.resource.XtextResource;
@@ -43,6 +43,7 @@ import org.eclipse.xtext.ui.common.editor.contentassist.IProposalProvider;
 import org.eclipse.xtext.ui.common.editor.contentassist.ITemplateContentAssistProcessor;
 import org.eclipse.xtext.ui.core.editor.model.IXtextDocument;
 import org.eclipse.xtext.ui.core.editor.model.UnitOfWork;
+import org.eclipse.xtext.util.Strings;
 
 import com.google.inject.Inject;
 
@@ -54,54 +55,22 @@ import com.google.inject.Inject;
  * @author Jan K&ouml;hnlein
  */
 public class DefaultContentAssistProcessor implements IContentAssistProcessor {
-
 	// logger available to subclasses
 	protected final Logger logger = Logger.getLogger(getClass());
-
 	@Inject
 	protected ITemplateContentAssistProcessor templateContentAssistProcessor;
-
 	@Inject
 	protected IContentAssistCalculator contentAssistCalculator;
-
 	@Inject
 	protected IProposalProvider proposalProvider;
-
 	/**
 	 * Computes the possible grammar elements following the one at the given offset and calls the respective methods on
 	 * the proposal provider.
 	 */
 	public ICompletionProposal[] computeCompletionProposals(final ITextViewer viewer, final int offset) {
-
 		IXtextDocument document = (IXtextDocument) viewer.getDocument();
-
-		return document.readOnly(new UnitOfWork<ICompletionProposal[]>() {
-
-			public ICompletionProposal[] exec(XtextResource resource) throws Exception {
-
-				IContentAssistContext contentAssistContext = createContext(resource, viewer, offset);
-
-				List<AbstractElement> computeProposalElements = contentAssistCalculator
-						.computeProposalElements(contentAssistContext);
-
-				List<ICompletionProposal> completionProposalList = collectCompletionProposals(computeProposalElements,
-						contentAssistContext);
-
-				for (TemplateContextType templateContextType : collectTemplateContextTypes(computeProposalElements,
-						contentAssistContext)) {
-					addTemplates(viewer, offset, contentAssistContext, templateContextType, completionProposalList);
-				}
-
-				List<? extends ICompletionProposal> processedCompletionProposalList = proposalProvider.sortAndFilter(
-						completionProposalList, contentAssistContext);
-
-				return processedCompletionProposalList.toArray(new ICompletionProposal[processedCompletionProposalList
-						.size()]);
-			}
-
-		});
+		return document.readOnly(new ContentAssistProcessorUow(offset, viewer));
 	}
-
 	/*
 	 * (non-Javadoc)
 	 * @see org.eclipse.jface.text.contentassist.IContentAssistProcessor#getCompletionProposalAutoActivationCharacters()
@@ -141,26 +110,7 @@ public class DefaultContentAssistProcessor implements IContentAssistProcessor {
 	public IContextInformationValidator getContextInformationValidator() {
 		return new ContextInformationValidator(this);
 	}
-
-	/**
-	 * adds templates to the list of proposals
-	 *
-	 * @param viewer the viewer whose document is used to compute the proposals
-	 * @param offset an offset within the document for which completions should be computed
-	 * @param contentAssistContext the current context of the content assist proposal request
-	 * @param templateContextType within which templates are resolved
-	 * @param completionProposalList list of proposal to add to
-	 */
-	protected void addTemplates(ITextViewer viewer, int offset, IContentAssistContext contentAssistContext,
-			TemplateContextType templateContextType, List<ICompletionProposal> completionProposalList) {
-		if (templateContentAssistProcessor != null) {
-			templateContentAssistProcessor.setContentAssistContext(contentAssistContext);
-			templateContentAssistProcessor.setContextType(templateContextType);
-			completionProposalList.addAll(Arrays.asList(templateContentAssistProcessor.computeCompletionProposals(
-					viewer, offset)));
-		}
-	}
-
+	
 	protected List<ICompletionProposal> collectCompletionProposals(List<AbstractElement> computeProposalElements, IContentAssistContext contentAssistContext) {
 		List<ICompletionProposal> completionProposalList = new ArrayList<ICompletionProposal>();
 		for (AbstractElement computeProposalElement : computeProposalElements) {
@@ -201,82 +151,116 @@ public class DefaultContentAssistProcessor implements IContentAssistProcessor {
 					break;
 				case XtextPackage.ASSIGNMENT:
 					// TODO: change interface
-					// templateContextType =
-					// proposalProvider.getTemplateContextType((Assignment)
-					// computeProposalElement, contentAssistContext);
+					// templateContextType = 
+					// proposalProvider.getTemplateContextType((Assignment)computeProposalElement, contentAssistContext);
 					// addIfNotNull(templateContextTypes, templateContextType);
 					break;
 			}
 		}
 		return templateContextTypes;
 	}
-
+	/**
+	 * Adds templates to the list of proposals,
+	 *
+	 * @param viewer the viewer whose document is used to compute the proposals
+	 * @param offset an offset within the document for which completions should be computed
+	 * @param contentAssistContext the current context of the content assist proposal request
+	 * @param templateContextType within which templates are resolved
+	 * @param completionProposalList list of proposal to add to
+	 */
+	protected void addTemplates(ITextViewer viewer, int offset, IContentAssistContext contentAssistContext,
+			TemplateContextType templateContextType, List<ICompletionProposal> completionProposalList) {
+		if (templateContentAssistProcessor != null) {
+			templateContentAssistProcessor.setContentAssistContext(contentAssistContext);
+			templateContentAssistProcessor.setContextType(templateContextType);
+			completionProposalList.addAll(Arrays.asList(templateContentAssistProcessor.computeCompletionProposals(
+					viewer, offset)));
+		}
+	}
 	/**
 	 * Creates a new <code>IContentAssistContext</code> with all required informations for the current CA request.
 	 *
 	 * @param resource the underlying EMF resource to read (parse) from
 	 * @param viewer the viewer whose document is used to compute the proposals
-	 * @param offset an offset within the document for which the context should be created
-	 * @return a matching context containing all necessary informations for the current content assist request
+	 * @param offset the offset within the resource for which the context should be created
+	 * @return a list of applicable <code>IContentAssistContext</code>
 	 */
-	protected IContentAssistContext createContext(XtextResource resource, ITextViewer viewer, final int offset) {
-
+	protected List<IContentAssistContext> createContextList(XtextResource resource, String text, final int offset) {
+		List<IContentAssistContext> result = new ArrayList<IContentAssistContext>();
 		IParseResult parseResult = resource.getParseResult();
-
 		Assert.isNotNull(parseResult);
-
 		CompositeNode rootNode = parseResult.getRootNode();
-
 		AbstractNode referenceNode = ParseTreeUtil.getLastCompleteNodeByOffset(rootNode, offset);
-
-		EObject model = NodeUtil.getNearestSemanticObject(referenceNode);
-
-		AbstractNode node = ParseTreeUtil.getCurrentOrFollowingNodeByOffset(rootNode, offset);
-
-		String matchingString = node == null ? "" : calculateMatchString(viewer, offset, node);
-
-		/**
-		 *
-		 * if cursor is behind a complete keyword, accept any input => empty
-		 *
-		 * TODO: Find a way to distinguish between keywords like "+" or "-" and
-		 * "extends" or "class" in the latter case, the prefix "" would not
-		 * always be sufficient
-		 * XXX SZ: the formatter may help to answer this question
-		 */
-		if (node != null && node.getGrammarElement() instanceof Keyword
-				&& (node instanceof LeafNode && ((LeafNode) node).getText().equals(matchingString))) {
-			matchingString = "";
+		AbstractNode nodeAtOffset = ParseTreeUtil.getCurrentOrFollowingNodeByOffset(rootNode, offset);
+		
+		if (referenceNode.getOffset()+referenceNode.getLength() == offset) {
+			AbstractNode precedingReferenceNode = ParseTreeUtil.getLastCompleteNodeByOffset(rootNode,Math.max(0, referenceNode.getOffset()-1));
+			String matchingString = calculateMatchString(nodeAtOffset,text, offset);
+			result.add(newCompletionProposal(matchingString, offset, rootNode, precedingReferenceNode));
+			if (!Strings.isEmpty(matchingString) && 
+					referenceNode.getGrammarElement() instanceof Keyword || 
+					referenceNode.getGrammarElement() instanceof CrossReference ||
+					(referenceNode.getGrammarElement() instanceof RuleCall &&
+					 ((RuleCall)referenceNode.getGrammarElement()).getRule() instanceof TerminalRule)) {
+				result.add(newCompletionProposal("", offset, rootNode, referenceNode));
+			}
+		} else {
+			String matchingString = calculateMatchString(nodeAtOffset,text, offset);
+			result.add(newCompletionProposal(matchingString, offset, rootNode, referenceNode));
 		}
-
-		return new ContentAssistContext(model, offset, matchingString, node, referenceNode, rootNode);
+		
+		return result;
 	}
-
 	/**
-	 * Calculates the match string of the current <code>IContentAssistContext</code> based on the
-	 * specified location within the text viewer.
+	 * Calculates the match string of the based on the specified location within the given text.
 	 *
-	 * @param viewer the viewer whose document is used to compute the proposals
+	 * @param caretNode the node at the current caret position
+	 * @param text the text to compute the matching string
 	 * @param offset an offset within the document for which the matchstring should be computed
 	 * @return a matching string
 	 */
-	protected String calculateMatchString(ITextViewer viewer, int offset,AbstractNode node) {
-
-		String prefix = "";
-
-		StyledText textWidget = viewer.getTextWidget();
+	protected String calculateMatchString(AbstractNode caretNode, String text, int offset) {
+		StringBuilder matchString = new StringBuilder();
+		char c = ' ';
+		while (offset>caretNode.getOffset() && !Character.isWhitespace(c = text.charAt(--offset))) {
+			matchString.insert(0, c);
+		}
+		return matchString.toString();
+	}
+	
+	private ContentAssistContext newCompletionProposal(String matchingString, final int offset, CompositeNode rootNode,
+			AbstractNode referenceNode) {
+		EObject model = NodeUtil.getNearestSemanticObject(referenceNode);
+		AbstractNode node = ParseTreeUtil.getCurrentOrFollowingNodeByOffset(rootNode, offset);
+		return new ContentAssistContext(model, offset, matchingString, node, referenceNode, rootNode);
+	}
+	
+	private final class ContentAssistProcessorUow implements UnitOfWork<ICompletionProposal[]> {
+		private final int offset;
+		private final ITextViewer viewer;
+
+		private ContentAssistProcessorUow(int offset, ITextViewer viewer) {
+			this.offset = offset;
+			this.viewer = viewer;
+		}
 
-		if (textWidget.getCharCount() > 0) {
-			int boundedOffset = Math.min(offset, textWidget.getCharCount()) - 1;
-			if (node.getTotalOffset() <= boundedOffset) {
-				prefix = textWidget.getText(node.getTotalOffset(), boundedOffset).trim();
+		public ICompletionProposal[] exec(XtextResource resource) throws Exception {
+			List<ICompletionProposal> completionProposalList = new ArrayList<ICompletionProposal>();
+			for (IContentAssistContext contentAssistContext : createContextList(
+					resource, viewer.getTextWidget().getText(), offset)) {
+				List<AbstractElement> computedElements = contentAssistCalculator
+						.computeProposalElements(contentAssistContext);
+				completionProposalList.addAll(collectCompletionProposals(computedElements,contentAssistContext));
+				for (TemplateContextType templateContextType : collectTemplateContextTypes(computedElements,
+						contentAssistContext)) {
+					addTemplates(viewer, offset, contentAssistContext, templateContextType, completionProposalList);
+				}
+				proposalProvider.filter(completionProposalList,contentAssistContext);
 			}
+			proposalProvider.sort(completionProposalList);
+			return completionProposalList.toArray(new ICompletionProposal[completionProposalList.size()]);
 		}
-
-		return prefix;
 	}
 
-
-
 }
 
diff --git a/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/JavaReflectiveMethodInvoker.java b/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/JavaReflectiveMethodInvoker.java
index fe2dd04..410017f 100644
--- a/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/JavaReflectiveMethodInvoker.java
+++ b/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/JavaReflectiveMethodInvoker.java
@@ -39,8 +39,7 @@ public class JavaReflectiveMethodInvoker {
 		if (method == null) {
 			return null;
 		}
-		Object result = invokeMethod(method, target, parameterValues.toArray(new Object[] {}));
-		return result;
+		return invokeMethod(method, target, parameterValues.toArray(new Object[] {}));
 	}
 
 	private final Method findMethod(Class<?> clazz, String name, Class<?>... paramTypes) {
diff --git a/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/ProposalFilterSorterUtil.java b/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/ProposalFilterSorterUtil.java
index 5aa1fc9..1ce2b99 100644
--- a/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/ProposalFilterSorterUtil.java
+++ b/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/ProposalFilterSorterUtil.java
@@ -18,29 +18,31 @@ import org.apache.log4j.Logger;
 import org.eclipse.jface.text.contentassist.ICompletionProposal;
 import org.eclipse.xtext.ui.common.editor.contentassist.IContentAssistContext;
 import org.eclipse.xtext.ui.common.editor.contentassist.IProposalProvider;
+import org.eclipse.xtext.util.Strings;
 
 /**
  * @author Jan Köhnlein - Initial contribution and API
+ * @author Michael Clay - Initial contribution and API
  */
 public class ProposalFilterSorterUtil {
+	private static Logger logger = Logger.getLogger(IProposalProvider.class);
+	
 	protected static final Comparator<ICompletionProposal> PROPOSAL_COMPARATOR = new Comparator<ICompletionProposal>() {
 		public int compare(ICompletionProposal o1, ICompletionProposal o2) {
 			return o1.getDisplayString().compareTo(o2.getDisplayString());
 		}
 	};
 	
-	private static Logger logger = Logger.getLogger(IProposalProvider.class);
-	
-	public static List<? extends ICompletionProposal> sortAndFilter(
+	public static List<? extends ICompletionProposal> filter(
 			List<? extends ICompletionProposal> completionProposalList, IContentAssistContext contentAssistContext) {
 		Map<String, ICompletionProposal> displayString2ICompletionProposalMap = new HashMap<String, ICompletionProposal>();
 		for (Iterator<? extends ICompletionProposal> iterator = completionProposalList.iterator(); iterator.hasNext();) {
 			ICompletionProposal completionProposal = iterator.next();
-			// filter duplicate
 			if (!displayString2ICompletionProposalMap.containsKey(completionProposal.getDisplayString())) {
 				displayString2ICompletionProposalMap.put(completionProposal.getDisplayString(), completionProposal);
-				// filter by prefix
-				if (isFiltered(completionProposal)) {
+				if (!Strings.isEmpty(contentAssistContext.getMatchString()) && 
+						(!completionProposal.getDisplayString().toUpperCase().startsWith(contentAssistContext.getMatchString().toUpperCase()) ||
+								completionProposal.getDisplayString().equalsIgnoreCase(contentAssistContext.getMatchString()))) {
 					if (logger.isDebugEnabled()) {
 						logger.debug("filter completionProposal '" + completionProposal + "'");
 					}
@@ -54,27 +56,12 @@ public class ProposalFilterSorterUtil {
 				iterator.remove();
 			}
 		}
-		Collections.sort(completionProposalList, PROPOSAL_COMPARATOR);
 		return completionProposalList;
 	}
-
-	/**
-	 * The default behavior of this method delegates to
-	 * {@link XtextCompletionProposal#matches(String)} to test if the given
-	 * prefix string matches or not.
-	 * 
-	 * @param completionProposal
-	 *            contains information used to present the proposed completion
-	 *            to the user
-	 * @return true or false whether the given prefix matches the text of this
-	 *         completion proposal
-	 */
-	protected static boolean isFiltered(ICompletionProposal completionProposal) {
-		if (completionProposal instanceof XtextCompletionProposal) {
-			XtextCompletionProposal xtextCompletionProposal = (XtextCompletionProposal) completionProposal;
-			return !xtextCompletionProposal.matches();
-		}
-		return false;
+	
+	public static List<? extends ICompletionProposal> sort(List<? extends ICompletionProposal> completionProposalList) { 
+		Collections.sort(completionProposalList, PROPOSAL_COMPARATOR);
+		return completionProposalList;
 	}
 
 }
diff --git a/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/XtextCompletionProposal.java b/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/XtextCompletionProposal.java
index 2dfcceb..93aa551 100644
--- a/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/XtextCompletionProposal.java
+++ b/plugins/org.eclipse.xtext.ui.common/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/XtextCompletionProposal.java
@@ -1,7 +1,6 @@
 package org.eclipse.xtext.ui.common.editor.contentassist.impl;
 
 import org.apache.log4j.Logger;
-import org.eclipse.emf.ecore.EObject;
 import org.eclipse.jface.text.BadLocationException;
 import org.eclipse.jface.text.IDocument;
 import org.eclipse.jface.text.contentassist.ICompletionProposal;
@@ -9,10 +8,6 @@ import org.eclipse.jface.text.contentassist.IContextInformation;
 import org.eclipse.swt.graphics.Image;
 import org.eclipse.swt.graphics.Point;
 import org.eclipse.xtext.AbstractElement;
-import org.eclipse.xtext.CrossReference;
-import org.eclipse.xtext.GrammarUtil;
-import org.eclipse.xtext.Keyword;
-import org.eclipse.xtext.ParserRule;
 import org.eclipse.xtext.ui.common.editor.contentassist.IContentAssistContext;
 
 /**
@@ -28,7 +23,6 @@ public class XtextCompletionProposal implements ICompletionProposal {
 	// logger available to subclasses
 	protected final Logger logger = Logger.getLogger(XtextCompletionProposal.class);
 
-	private final AbstractElement abstractElement;
 	private final String text;
 	private int selectionOffset;
 
@@ -37,19 +31,14 @@ public class XtextCompletionProposal implements ICompletionProposal {
 	private int nodeTotalOffset;
 	private int nodeTotalLength;
 	private String matchString;
-	private EObject grammarElement;
-	private boolean isCusorAtEndOfLastCompleteNode;
 
 	public XtextCompletionProposal(AbstractElement abstractElement, String displayString,
 			IContentAssistContext contentAssistContext) {
-		this.abstractElement = abstractElement;
 		this.text = displayString;
 		this.offset = contentAssistContext.getOffSet();
 		this.nodeTotalOffset = contentAssistContext.getNode().getTotalOffset();
 		this.nodeTotalLength = contentAssistContext.getNode().getTotalLength();
 		this.matchString = contentAssistContext.getMatchString();
-		this.grammarElement = contentAssistContext.getNode().getGrammarElement();
-		this.isCusorAtEndOfLastCompleteNode = contentAssistContext.getNode() == contentAssistContext.getReferenceNode();
 	}
 
 	public void apply(IDocument document) {
@@ -87,52 +76,9 @@ public class XtextCompletionProposal implements ICompletionProposal {
 		return new Point(this.selectionOffset, 0);
 	}
 
-	/**
-	 * 
-	 * @return true or false whether the given prefix matches the text of this
-	 *         completion proposal
-	 */
-	public boolean matches() {
-		boolean matches = true;
-		AbstractElement abstractElement = null;
-		if (this.abstractElement instanceof Keyword || this.abstractElement instanceof CrossReference) {
-			abstractElement = GrammarUtil.containingAssignment(this.abstractElement);
-		}
-		if (null == abstractElement) {
-			abstractElement = this.abstractElement;
-		}
-		boolean candidateToCompare = false;
-
-		// means if we are at the end of a complete token we want to filter only
-		// equal grammarelements (not the 'next' ones)
-		if (isCusorAtEndOfLastCompleteNode && abstractElement.equals(getCurrentGrammarElement())) {
-			candidateToCompare = true;
-		}
-		else if (!isCusorAtEndOfLastCompleteNode) {
-			candidateToCompare = true;
-		}
-		if (candidateToCompare
-				&& (!"".equals(matchString.trim()) && !getDisplayString().toUpperCase().trim().startsWith(
-						matchString.toUpperCase().trim()))) {
-			matches = false;
-		}
-		return matches;
-	}
-
 	@Override
 	public String toString() {
 		return "XtextCompletionPoposal[text='" + this.text + "']";
 	}
 
-	/**
-	 * @return the grammar element of the current node
-	 */
-	public EObject getCurrentGrammarElement() {
-		EObject containingAssignment = GrammarUtil.containingAssignment(grammarElement);
-		if (containingAssignment == null) {
-			return grammarElement instanceof ParserRule ? ((ParserRule) grammarElement).getAlternatives()
-					: grammarElement;
-		}
-		return containingAssignment;
-	}
 }
diff --git a/plugins/org.eclipse.xtext.xtend/src/org/eclipse/xtext/xtend/contentassist/AbstractXtendProposalProvider.java b/plugins/org.eclipse.xtext.xtend/src/org/eclipse/xtext/xtend/contentassist/AbstractXtendProposalProvider.java
index 5e19132..d614583 100644
--- a/plugins/org.eclipse.xtext.xtend/src/org/eclipse/xtext/xtend/contentassist/AbstractXtendProposalProvider.java
+++ b/plugins/org.eclipse.xtext.xtend/src/org/eclipse/xtext/xtend/contentassist/AbstractXtendProposalProvider.java
@@ -12,8 +12,6 @@ import java.util.Collections;
 import java.util.List;
 
 import org.apache.log4j.Logger;
-import org.eclipse.emf.ecore.EObject;
-import org.eclipse.jface.text.IDocument;
 import org.eclipse.jface.text.contentassist.ICompletionProposal;
 import org.eclipse.jface.text.templates.Template;
 import org.eclipse.jface.text.templates.TemplateContextType;
@@ -25,8 +23,6 @@ import org.eclipse.xtext.ParserRule;
 import org.eclipse.xtext.RuleCall;
 import org.eclipse.xtext.TerminalRule;
 import org.eclipse.xtext.TypeRef;
-import org.eclipse.xtext.parsetree.AbstractNode;
-import org.eclipse.xtext.parsetree.LeafNode;
 import org.eclipse.xtext.ui.common.editor.contentassist.IContentAssistContext;
 import org.eclipse.xtext.ui.common.editor.contentassist.IProposalProvider;
 import org.eclipse.xtext.ui.common.editor.contentassist.impl.AbstractJavaProposalProvider;
@@ -168,21 +164,21 @@ public abstract class AbstractXtendProposalProvider extends AbstractXtendService
 	protected String getDefaultImageFilePath() {
 		return "icons/editor.gif";
 	}
+	
+	/*
+	 * (non-Javadoc)
+	 * @see org.eclipse.xtext.ui.common.editor.contentassist.IProposalProvider#filter(java.util.List, org.eclipse.xtext.ui.common.editor.contentassist.IContentAssistContext)
+	 */
+	public List<? extends ICompletionProposal> filter(List<ICompletionProposal> completionProposalList,
+			IContentAssistContext contentAssistContext) {
+		return ProposalFilterSorterUtil.filter(completionProposalList,contentAssistContext);
+	}
 
-	/**
-	 * Concrete subclasses can override this for custom sort and filter
-	 * behavior. Called right after all completion proposals have been
-	 * collected.
-	 *
-	 * The default behavior of this implementation is to filter duplicates and
-	 * to trim matching <code>ICompletionProposal#displayString</code> with
-	 * matching prefix values.
-	 *
-	 * @see #sortAndFilter(List, EObject, String, IDocument, int, AbstractNode,
-	 *      LeafNode)
+	/*
+	 * (non-Javadoc)
+	 * @see org.eclipse.xtext.ui.common.editor.contentassist.IProposalProvider#sort(java.util.List)
 	 */
-	public List<? extends ICompletionProposal> sortAndFilter(
-			List<? extends ICompletionProposal> completionProposalList, IContentAssistContext contentAssistContext) {
-		return ProposalFilterSorterUtil.sortAndFilter(completionProposalList, contentAssistContext);
+	public List<? extends ICompletionProposal> sort(List<ICompletionProposal> completionProposalList) {
+		return ProposalFilterSorterUtil.sort(completionProposalList);
 	}
 }
diff --git a/tests/org.eclipse.xtext.ui.common.tests/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/ContentAssistProcessorTestBuilder.java b/tests/org.eclipse.xtext.ui.common.tests/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/ContentAssistProcessorTestBuilder.java
index 3b769ab..c4bd6e9 100644
--- a/tests/org.eclipse.xtext.ui.common.tests/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/ContentAssistProcessorTestBuilder.java
+++ b/tests/org.eclipse.xtext.ui.common.tests/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/ContentAssistProcessorTestBuilder.java
@@ -13,7 +13,8 @@
  *******************************************************************************/
 package org.eclipse.xtext.ui.common.editor.contentassist.impl;
 
-import static org.easymock.EasyMock.*;
+import static org.easymock.EasyMock.expect;
+import static org.easymock.EasyMock.replay;
 
 import java.lang.reflect.InvocationHandler;
 import java.lang.reflect.Method;
@@ -128,24 +129,19 @@ public class ContentAssistProcessorTestBuilder extends AbstractXtextTests {
 
 	public ContentAssistProcessorTestBuilder assertMatchString(String matchString)
 			throws Exception {
-
-		final String currentModelToParse = getModel();
-
+		String currentModelToParse = getModel();
 		final XtextResource xtextResource = getResource(new StringInputStream(currentModelToParse));
-
-		final IXtextDocument xtextDocument = getDocument(xtextResource);
-
-		IContentAssistContext contentAssistContext = new DefaultContentAssistProcessor() {
+		List<IContentAssistContext> contentAssistContextList = new DefaultContentAssistProcessor() {
 			@Override
-			public IContentAssistContext createContext(XtextResource resource, ITextViewer viewer, int offset) {
-				IContentAssistContext createContext = super.createContext(resource,viewer,offset);
-				return createContext;
+			public List<IContentAssistContext> createContextList(XtextResource resource, String text, final int offset) {
+				return super.createContextList(xtextResource, text, offset);
 			}
-		}.createContext(xtextResource, resetTextViewerMock(currentModelToParse, xtextDocument),cursorPosition);
-
-
-		assertEquals(matchString, contentAssistContext.getMatchString());
-
+		}.createContextList(xtextResource, currentModelToParse,cursorPosition);
+		
+		for (IContentAssistContext contentAssistContext : contentAssistContextList) {		
+			assertEquals(matchString, contentAssistContext.getMatchString());
+			break;
+		}
 		return this;
 	}
 
@@ -169,8 +165,15 @@ public class ContentAssistProcessorTestBuilder extends AbstractXtextTests {
 		ICompletionProposal[] computeCompletionProposals = computeCompletionProposals(currentModelToParse,
 				cursorPosition);
 
+		StringBuffer computedProposals = new StringBuffer();
+		for (int i = 0; i < computeCompletionProposals.length; i++) {
+			computedProposals.append(computeCompletionProposals[i].getDisplayString());
+			if (i<(computeCompletionProposals.length-1)) {
+				computedProposals.append(",");
+			}
+		}
 		assertEquals("expect only " + completionProposalCount + " CompletionProposal item for model '"
-				+ currentModelToParse + "'", completionProposalCount, computeCompletionProposals.length);
+				+ currentModelToParse + "' but got '"+computedProposals+"'", completionProposalCount, computeCompletionProposals.length);
 
 		return this;
 	}
@@ -211,7 +214,7 @@ public class ContentAssistProcessorTestBuilder extends AbstractXtextTests {
 	private ITextViewer resetTextViewerMock(final String currentModelToParse, final IXtextDocument xtextDocument) {
 		EasyMock.reset(textViewerMock);
 		expect(textViewerMock.getDocument()).andReturn(xtextDocument);
-		expect(textViewerMock.getTextWidget()).andReturn(newStyledTextWidgetMock(currentModelToParse));
+		expect(textViewerMock.getTextWidget()).andReturn(newStyledTextWidgetMock(currentModelToParse)).times(2);
 		replay(textViewerMock);
 		return textViewerMock;
 	}
@@ -234,6 +237,11 @@ public class ContentAssistProcessorTestBuilder extends AbstractXtextTests {
 			public String getText(int start, int end) {
 				return testDslModel.substring(start, end + 1);
 			}
+			
+			@Override
+			public String getText() {
+				return testDslModel;
+			}
 		};
 	}
 
diff --git a/tests/org.eclipse.xtext.ui.common.tests/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/DefaultContentAssistProcessorTest.java b/tests/org.eclipse.xtext.ui.common.tests/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/DefaultContentAssistProcessorTest.java
index da97e85..c45ee91 100644
--- a/tests/org.eclipse.xtext.ui.common.tests/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/DefaultContentAssistProcessorTest.java
+++ b/tests/org.eclipse.xtext.ui.common.tests/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/DefaultContentAssistProcessorTest.java
@@ -40,9 +40,8 @@ import com.google.inject.Injector;
  * @author Jan Koehnlein

  * @see org.eclipse.xtext.ui.common.editor.contentassist.impl.DefaultContentAssistProcessor

  */

-public class DefaultContentAssistProcessorTest extends AbstractXtextTests

-{

-

+public class DefaultContentAssistProcessorTest extends AbstractXtextTests {	

+	

 	private ISetup getRefGrammarSetup() {

 		return new ReferenceGrammarTestLanguageStandaloneSetup() {

 			@Override

@@ -80,11 +79,12 @@ public class DefaultContentAssistProcessorTest extends AbstractXtextTests
 	}

 

 	public void testComputePrefix() throws Exception {

+		String model = "spielplatz 1 \"SpielplatzBeschreibung\" { kind(k1 0) kind(k2 0) erwachsener(e1 0) erwachsener(e2 0) ";

 		newBuilder(getRefGrammarSetup())

-		.append("foo fvdf dfv(").assertMatchString("(").reset()

-		.append("foo fvdf dfv").assertMatchString("dfv").reset()

-		.append("foo fvdf dfv_").assertMatchString("dfv_").reset()

-		.append("foo fvdf dfv_ ").assertMatchString("").reset()

+		.append(model+" familie( dfv(").assertMatchString("(").reset()

+		.append(model+" familie( dfv").assertMatchString("dfv").reset()

+		.append(model+" familie( dfv_").assertMatchString("dfv_").reset()

+		.append(model+" familie( dfv_ ").assertMatchString("").reset()

 		.append("").assertMatchString("");

 	}

 

@@ -134,13 +134,13 @@ public class DefaultContentAssistProcessorTest extends AbstractXtextTests
 		builder.append(" ER").assertText("erwachsener");

 		builder.append(" SP").assertText("spielzeug");

 		builder.append(" FA").assertText("familie");

-		builder.append(" familie ( KEY").assertText("keyword");

-		builder.append(" familie ( K").assertText("keyword");

+		builder.append(" familie ( KEY").assertText("keyword","e1","e2");

+		builder.append(" familie ( K").assertText("keyword","e1","e2");

 		builder.append(" familie ( keyword E").assertText("e1", "e2");

-		builder.append(" familie ( keyword e1 E").assertText("e1", "e2");

+		builder.append(" familie ( keyword e1 E").assertText("e1", "e2","k1","k2");

 		builder.append(" familie ( keyword e1 e2 K").assertText("k1", "k2", ",", ")");

-		builder.append(" familie ( keyword e1 e2 k1,K").assertText("k1", "k2", ",", ")");

-		builder.append(" familie ( keyword e1 e2 k1,k2").assertText("k2", ",", ")");

+		builder.append(" familie ( keyword e1 e2 k1,K").assertText(",", ")");

+		builder.append(" familie ( keyword e1 e2 k1,k2").assertText(",", ")");

 	}

 

 	/**

@@ -189,8 +189,7 @@ public class DefaultContentAssistProcessorTest extends AbstractXtextTests
 					"R3",

 					"\"Keyword_Value\"",

 					"(",

-					"[",

-					"+=" // TODO: Why does this proposal come up?

+					"["

 			);

 	}

 

@@ -200,8 +199,7 @@ public class DefaultContentAssistProcessorTest extends AbstractXtextTests
 			.appendNl("R1 ();")

 			.append("R2 rule :").assertText(

 					"R1",

-					"R2",

-					":" // TODO: Why does this proposal come up?

+					"R2"

 			);

 	}

 

@@ -223,25 +221,22 @@ public class DefaultContentAssistProcessorTest extends AbstractXtextTests
                     .appendNl("MyRule : 'foo' name=ID; ").assertText(

                                     "ParserRule_Name", "terminal"

                     );

-

     }

 

     /**

-     * SZ: uncomment because it fails and neither the result nor the excpectation

-     * seem to be right

      * regression test for:

      *

      * https://bugs.eclipse.org/bugs/show_bug.cgi?id=260825

      * https://bugs.eclipse.org/bugs/show_bug.cgi?id=262313

      */

-//    public void testCompleteAssignmentWithBacktracking() throws Exception {

-//    	newBuilder(getXtextGrammarSetup())

-//                    .appendNl("grammar foo with org.eclipse.xtext.common.Terminals")

-//                    .appendNl("generate foo \"foo\"")

-//                    .append("MyRule : 'foo' name").assertText(

-//                                    "*", "+", "+=", ";", "=", "?", "?="

-//                    );

-//    }

+    public void testCompleteAssignmentWithBacktracking() throws Exception {

+    	newBuilder(getXtextGrammarSetup())

+        .appendNl("grammar foo with org.eclipse.xtext.common.Terminals")

+        .appendNl("generate foo \"foo\"")

+        .append("MyRule : 'foo' name").assertText("\"Keyword_Value\"", "(", "*", "+", "+=", ";", "=", "?", "?=", 

+        		"Assignment_Feature", "MyRule",  "{");

+

+    }

 

     public void testKeywordWithBackslashes() throws Exception {

 		newBuilder(getKeywordsLangSetup())

diff --git a/tests/org.eclipse.xtext.ui.common.tests/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/TwoContextsContentAssistTest.java b/tests/org.eclipse.xtext.ui.common.tests/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/TwoContextsContentAssistTest.java
index 8d86507..f642c9c 100644
--- a/tests/org.eclipse.xtext.ui.common.tests/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/TwoContextsContentAssistTest.java
+++ b/tests/org.eclipse.xtext.ui.common.tests/src/org/eclipse/xtext/ui/common/editor/contentassist/impl/TwoContextsContentAssistTest.java
@@ -27,10 +27,7 @@ import com.google.inject.Injector;
 public class TwoContextsContentAssistTest extends AbstractXtextTests {
 
 	public void testTwoContexts() throws Exception {
-		System.err.println(getClass().getSimpleName()+" says: PLEASE ACTIVATE ME!");
-//    	newBuilder(getGrammarSetup())
-//                    .append("Foo; FooBar; Bar refersTo Foo").assertText(
-//                                    ";", "FooBar");
+    	newBuilder(getGrammarSetup()).append("Foo; FooBar; Bar refersTo Foo").assertText(";", "FooBar");
     }
 
     /**