302201 : Unify the two query approaches used in p2, step 3.

34 files changed, 281 insertions, 406 deletions

diff --git a/bundles/org.eclipse.equinox.p2.director/src/org/eclipse/equinox/internal/p2/director/ApplicablePatchQuery.java b/bundles/org.eclipse.equinox.p2.director/src/org/eclipse/equinox/internal/p2/director/ApplicablePatchQuery.java
index 4e6f0ba6f..37b347b7d 100644
--- a/bundles/org.eclipse.equinox.p2.director/src/org/eclipse/equinox/internal/p2/director/ApplicablePatchQuery.java
+++ b/bundles/org.eclipse.equinox.p2.director/src/org/eclipse/equinox/internal/p2/director/ApplicablePatchQuery.java
@@ -7,20 +7,22 @@
  * 
  *  Contributors:
  *      IBM Corporation - initial API and implementation
+ *      Cloudsmith Inc. - converted into expression based query
  *******************************************************************************/
 package org.eclipse.equinox.internal.p2.director;
 
-import org.eclipse.equinox.p2.metadata.IInstallableUnitPatch;
-
 import org.eclipse.equinox.p2.metadata.IInstallableUnit;
-import org.eclipse.equinox.p2.metadata.IRequirement;
-import org.eclipse.equinox.p2.query.MatchQuery;
+import org.eclipse.equinox.p2.metadata.IInstallableUnitPatch;
+import org.eclipse.equinox.p2.metadata.expression.ExpressionUtil;
+import org.eclipse.equinox.p2.metadata.expression.IExpression;
+import org.eclipse.equinox.p2.metadata.query.ExpressionQuery;
 
 /**
  * A query that accepts any patch that applies to a given installable unit.
  */
-public class ApplicablePatchQuery extends MatchQuery<IInstallableUnit> {
-	IInstallableUnit iu;
+public class ApplicablePatchQuery extends ExpressionQuery<IInstallableUnit> {
+	private static final IExpression applicablePatches = ExpressionUtil.parse(//
+			"applicabilityScope.empty || applicabilityScope.exists(rqArr | rqArr.all(rq | $0 ~= rq))"); //$NON-NLS-1$
 
 	/**
 	 * Creates a new patch query on the given installable unit. Patches that can
@@ -28,26 +30,6 @@ public class ApplicablePatchQuery extends MatchQuery<IInstallableUnit> {
 	 * @param iu The unit to compare patches against
 	 */
 	public ApplicablePatchQuery(IInstallableUnit iu) {
-		this.iu = iu;
-	}
-
-	public boolean isMatch(IInstallableUnit candidate) {
-		if (!(candidate instanceof IInstallableUnitPatch))
-			return false;
-		IInstallableUnitPatch patchIU = (IInstallableUnitPatch) candidate;
-		IRequirement[][] scopeDescription = patchIU.getApplicabilityScope();
-		if (scopeDescription.length == 0)
-			return true;
-
-		for (int i = 0; i < scopeDescription.length; i++) {
-			int matchedScopeEntry = scopeDescription[i].length;
-			for (int j = 0; j < scopeDescription[i].length; j++) {
-				if (iu.satisfies(scopeDescription[i][j]))
-					matchedScopeEntry--;
-			}
-			if (matchedScopeEntry == 0)
-				return true;
-		}
-		return false;
+		super(IInstallableUnitPatch.class, applicablePatches, iu);
 	}
 }
diff --git a/bundles/org.eclipse.equinox.p2.directorywatcher/src/org/eclipse/equinox/internal/provisional/p2/directorywatcher/RepositoryListener.java b/bundles/org.eclipse.equinox.p2.directorywatcher/src/org/eclipse/equinox/internal/provisional/p2/directorywatcher/RepositoryListener.java
index dcf0dd358..3d7c91ba8 100644
--- a/bundles/org.eclipse.equinox.p2.directorywatcher/src/org/eclipse/equinox/internal/provisional/p2/directorywatcher/RepositoryListener.java
+++ b/bundles/org.eclipse.equinox.p2.directorywatcher/src/org/eclipse/equinox/internal/provisional/p2/directorywatcher/RepositoryListener.java
@@ -20,11 +20,13 @@ import org.eclipse.equinox.internal.p2.core.helpers.LogHelper;
 import org.eclipse.equinox.internal.p2.update.Site;
 import org.eclipse.equinox.p2.core.ProvisionException;
 import org.eclipse.equinox.p2.metadata.IInstallableUnit;
+import org.eclipse.equinox.p2.metadata.query.ExpressionQuery;
 import org.eclipse.equinox.p2.metadata.query.InstallableUnitQuery;
 import org.eclipse.equinox.p2.publisher.*;
 import org.eclipse.equinox.p2.publisher.eclipse.BundlesAction;
 import org.eclipse.equinox.p2.publisher.eclipse.FeaturesAction;
-import org.eclipse.equinox.p2.query.*;
+import org.eclipse.equinox.p2.query.IMatchQuery;
+import org.eclipse.equinox.p2.query.IQueryResult;
 import org.eclipse.equinox.p2.repository.IRepository;
 import org.eclipse.equinox.p2.repository.artifact.*;
 import org.eclipse.equinox.p2.repository.metadata.IMetadataRepository;
@@ -212,19 +214,11 @@ public class RepositoryListener extends DirectoryChangeListener {
 		if (!removedFiles.isEmpty() || !changes.isEmpty()) {
 			metadataRepository.removeInstallableUnits(changes.toArray(new IInstallableUnit[changes.size()]), null);
 
-			// create a query that will identify all ius related to removed files
-			IMatchQuery<IInstallableUnit> removeQuery = new MatchQuery<IInstallableUnit>() {
-				public boolean isMatch(IInstallableUnit iu) {
-					String filename = iu.getProperty(FILE_NAME);
-					if (filename == null) {
-						String message = NLS.bind(Messages.filename_missing, "installable unit", iu.getId()); //$NON-NLS-1$
-						LogHelper.log(new Status(IStatus.ERROR, Activator.ID, message, null));
-						return false;
-					}
-					File iuFile = new File(filename);
-					return removedFiles.contains(iuFile);
-				}
-			};
+			// create a query that will identify all ius related to removed files.
+			// It's safe to compare a String with a File since the auto coercion will
+			// first convert the String into a File.
+			IMatchQuery<IInstallableUnit> removeQuery = new ExpressionQuery<IInstallableUnit>(IInstallableUnit.class, //
+					"$1.exists(x | properties[$0] == x)", FILE_NAME, removedFiles); //$NON-NLS-1$
 			IQueryResult<IInstallableUnit> toRemove = metadataRepository.query(removeQuery, null);
 			metadataRepository.removeInstallableUnits(toRemove.toArray(IInstallableUnit.class), null);
 		}
diff --git a/bundles/org.eclipse.equinox.p2.engine/src/org/eclipse/equinox/p2/engine/query/IUProfilePropertyQuery.java b/bundles/org.eclipse.equinox.p2.engine/src/org/eclipse/equinox/p2/engine/query/IUProfilePropertyQuery.java
index 7c7510130..485094bf2 100644
--- a/bundles/org.eclipse.equinox.p2.engine/src/org/eclipse/equinox/p2/engine/query/IUProfilePropertyQuery.java
+++ b/bundles/org.eclipse.equinox.p2.engine/src/org/eclipse/equinox/p2/engine/query/IUProfilePropertyQuery.java
@@ -7,6 +7,7 @@
  * 
  *  Contributors:
  *     IBM Corporation - initial API and implementation
+ *     Cloudsmith Inc. - converted into expression based query
  *******************************************************************************/
 package org.eclipse.equinox.p2.engine.query;
 
diff --git a/bundles/org.eclipse.equinox.p2.engine/src/org/eclipse/equinox/p2/engine/query/UserVisibleRootQuery.java b/bundles/org.eclipse.equinox.p2.engine/src/org/eclipse/equinox/p2/engine/query/UserVisibleRootQuery.java
index d2c3318ad..a43ab9a40 100644
--- a/bundles/org.eclipse.equinox.p2.engine/src/org/eclipse/equinox/p2/engine/query/UserVisibleRootQuery.java
+++ b/bundles/org.eclipse.equinox.p2.engine/src/org/eclipse/equinox/p2/engine/query/UserVisibleRootQuery.java
@@ -7,6 +7,7 @@
  * 
  *  Contributors:
  *     IBM Corporation - initial API and implementation
+ *     Cloudsmith Inc. - converted into expression based query
  *******************************************************************************/
 package org.eclipse.equinox.p2.engine.query;
 
diff --git a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/InstallableUnitPatch.java b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/InstallableUnitPatch.java
index 6dee5de7b..6d6ab11b6 100644
--- a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/InstallableUnitPatch.java
+++ b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/InstallableUnitPatch.java
@@ -13,6 +13,10 @@ import org.eclipse.equinox.internal.p2.core.helpers.CollectionUtils;
 import org.eclipse.equinox.p2.metadata.*;
 
 public class InstallableUnitPatch extends InstallableUnit implements IInstallableUnitPatch {
+	public static final String MEMBER_APPLICABILITY_SCOPE = "applicabilityScope"; //$NON-NLS-1$
+	public static final String MEMBER_LIFECYCLE = "lifeCycle"; //$NON-NLS-1$
+	public static final String MEMBER_REQUIREMENTS_CHANGE = "requirementsChange"; //$NON-NLS-1$
+
 	private IRequirementChange[] changes;
 	private IRequirement lifeCycle;
 	private IRequirement[][] scope;
@@ -55,9 +59,11 @@ public class InstallableUnitPatch extends InstallableUnit implements IInstallabl
 	}
 
 	public Object getMember(String memberName) {
-		if ("lifeCycle".equals(memberName)) //$NON-NLS-1$
+		if (MEMBER_APPLICABILITY_SCOPE == memberName)
+			return scope;
+		if (MEMBER_LIFECYCLE == memberName)
 			return lifeCycle;
-		if ("requirementsChange".equals(memberName)) //$NON-NLS-1$
+		if (MEMBER_REQUIREMENTS_CHANGE == memberName)
 			return changes;
 		return super.getMember(memberName);
 	}
diff --git a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/TranslationSupport.java b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/TranslationSupport.java
index 862d15014..9701bfb4b 100644
--- a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/TranslationSupport.java
+++ b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/TranslationSupport.java
@@ -19,10 +19,8 @@ import org.eclipse.core.runtime.Status;
 import org.eclipse.equinox.internal.p2.core.helpers.LogHelper;
 import org.eclipse.equinox.internal.provisional.p2.metadata.MetadataFactory;
 import org.eclipse.equinox.p2.metadata.*;
-import org.eclipse.equinox.p2.metadata.expression.ExpressionUtil;
-import org.eclipse.equinox.p2.metadata.expression.IExpression;
+import org.eclipse.equinox.p2.metadata.expression.*;
 import org.eclipse.equinox.p2.metadata.query.ExpressionQuery;
-import org.eclipse.equinox.p2.metadata.query.FragmentQuery;
 import org.eclipse.equinox.p2.query.*;
 import org.eclipse.osgi.service.localization.LocaleProvider;
 
@@ -42,7 +40,8 @@ public class TranslationSupport {
 	static final String NAMESPACE_IU_LOCALIZATION = "org.eclipse.equinox.p2.localization"; //$NON-NLS-1$
 	private IQueryable<IInstallableUnit> fragmentSource;
 
-	private static IExpression capabilityMatch = ExpressionUtil.parse("providedCapabilities.exists(x | x.name == $0 && x.namespace == $1)"); //$NON-NLS-1$
+	private static IExpression capabilityMatch = ExpressionUtil.parse("providedCapabilities.exists(x | x.namespace == $0 && $1.exists(n | x.name == n))"); //$NON-NLS-1$
+	private static IExpression haveHostMatch = ExpressionUtil.parse("host.exists(h | $0 ~= h)"); //$NON-NLS-1$
 
 	// Cache the IU fragments that provide localizations for a given locale.
 	// Map<String,SoftReference<IQueryResult>>: locale => soft reference to a queryResult
@@ -222,15 +221,7 @@ public class TranslationSupport {
 				return cached;
 		}
 
-		final List<String> locales = localeVariants;
-
-		@SuppressWarnings("unchecked")
-		IQuery<IInstallableUnit>[] localeQuery = new IQuery[locales.size()];
-		for (int j = 0; j < locales.size(); j++) {
-			localeQuery[j] = new ExpressionQuery<IInstallableUnit>(IInstallableUnit.class, capabilityMatch, locales.get(j), NAMESPACE_IU_LOCALIZATION);
-		}
-
-		IQuery<IInstallableUnit> iuQuery = PipedQuery.createPipe(new FragmentQuery(), CompoundQuery.createCompoundQuery(localeQuery, false));
+		IQuery<IInstallableUnit> iuQuery = new ExpressionQuery<IInstallableUnit>(IInstallableUnitFragment.class, capabilityMatch, NAMESPACE_IU_LOCALIZATION, localeVariants);
 		IQueryResult<IInstallableUnit> collected = fragmentSource.query(iuQuery, null);
 		localeCollectorCache.put(locale, new SoftReference<IQueryResult<IInstallableUnit>>(collected));
 		return collected;
@@ -254,24 +245,8 @@ public class TranslationSupport {
 
 		IQueryResult<IInstallableUnit> localizationFragments = getLocalizationFragments(locales, locale);
 
-		IQuery<IInstallableUnit> hostLocalizationQuery = new MatchQuery<IInstallableUnit>() {
-			public boolean isMatch(IInstallableUnit object) {
-				boolean haveHost = false;
-				if (object instanceof IInstallableUnitFragment) {
-					IInstallableUnitFragment fragment = (IInstallableUnitFragment) object;
-					IRequirement[] hosts = fragment.getHost();
-					for (int i = 0; i < hosts.length; i++) {
-						if (theUnit.satisfies(hosts[i])) {
-							haveHost = true;
-							break;
-						}
-					}
-				}
-				return haveHost;
-			}
-		};
-
-		IQuery<IInstallableUnit> iuQuery = PipedQuery.createPipe(new FragmentQuery(), hostLocalizationQuery);
+		IExpressionFactory factory = ExpressionUtil.getFactory();
+		IQuery<IInstallableUnit> iuQuery = new ExpressionQuery<IInstallableUnit>(IInstallableUnitFragment.class, factory.matchExpression(haveHostMatch, theUnit));
 		IQueryResult<IInstallableUnit> collected = iuQuery.perform(localizationFragments.iterator());
 		if (!collected.isEmpty()) {
 			String translation = null;
diff --git a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/expression/ExpressionFactory.java b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/expression/ExpressionFactory.java
index c02133f2e..46bc7f55d 100644
--- a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/expression/ExpressionFactory.java
+++ b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/expression/ExpressionFactory.java
@@ -80,6 +80,10 @@ public class ExpressionFactory implements IExpressionFactory, IExpressionConstan
 		return new LambdaExpression((Variable) variable, (Expression) body);
 	}
 
+	public IExpression latest(IExpression collection) {
+		throw failNoQL();
+	}
+
 	public IExpression less(IExpression lhs, IExpression rhs) {
 		return new Compare((Expression) lhs, (Expression) rhs, true, false);
 	}
@@ -105,6 +109,10 @@ public class ExpressionFactory implements IExpressionFactory, IExpressionConstan
 	}
 
 	public IExpression member(IExpression target, String name) {
+		if ("empty".equals(name)) //$NON-NLS-1$
+			return new Member.EmptyMember((Expression) target);
+		if ("length".equals(name)) //$NON-NLS-1$
+			return new Member.LengthMember((Expression) target);
 		return new Member.DynamicMember((Expression) target, name);
 	}
 
diff --git a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/expression/Member.java b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/expression/Member.java
index ab08fffed..5af889ac7 100644
--- a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/expression/Member.java
+++ b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/expression/Member.java
@@ -11,6 +11,7 @@
 package org.eclipse.equinox.internal.p2.metadata.expression;
 
 import java.lang.reflect.*;
+import java.util.*;
 import org.eclipse.equinox.p2.metadata.expression.*;
 
 /**
@@ -103,6 +104,50 @@ public abstract class Member extends Unary {
 		}
 	}
 
+	public static class LengthMember extends Member {
+		private static final Integer ZERO = new Integer(0);
+
+		LengthMember(Expression operand) {
+			super(operand, "length", Expression.emptyArray); //$NON-NLS-1$
+		}
+
+		public Object evaluate(IEvaluationContext context) {
+			int len = getLength(operand.evaluate(context));
+			return len == 0 ? ZERO : new Integer(len);
+		}
+
+		int getLength(Object val) {
+			if (val == null)
+				return 0;
+
+			if (val.getClass().isArray())
+				return Array.getLength(val);
+
+			if (val instanceof Collection<?>)
+				return ((Collection<?>) val).size();
+
+			if (val instanceof String)
+				return ((String) val).length();
+
+			if (val instanceof Map<?, ?>)
+				return ((Map<?, ?>) val).size();
+
+			return 0;
+		}
+	}
+
+	public static class EmptyMember extends LengthMember {
+		EmptyMember(Expression operand) {
+			super(operand);
+		}
+
+		public Object evaluate(IEvaluationContext context) {
+			Object val = operand.evaluate(context);
+			boolean empty = (val instanceof Iterator<?>) ? !((Iterator<?>) val).hasNext() : getLength(val) == 0;
+			return Boolean.valueOf(empty);
+		}
+	}
+
 	static final Object[] NO_ARGS = new Object[0];
 
 	static Member createDynamicMember(Expression operand, String name) {
diff --git a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/query/IUPropertyQuery.java b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/query/IUPropertyQuery.java
index 1013e91aa..c8bc55d7e 100644
--- a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/query/IUPropertyQuery.java
+++ b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/query/IUPropertyQuery.java
@@ -7,6 +7,7 @@
  * 
  *  Contributors:
  *     IBM Corporation - initial API and implementation
+ *     Cloudsmith Inc. - converted into expression based query
  *******************************************************************************/
 package org.eclipse.equinox.internal.p2.metadata.query;
 
diff --git a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/query/LatestIUVersionQuery.java b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/query/LatestIUVersionQuery.java
index fc269117f..2e9b4b0c2 100644
--- a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/query/LatestIUVersionQuery.java
+++ b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/query/LatestIUVersionQuery.java
@@ -6,73 +6,40 @@
 *
 * Contributors:
 *   EclipseSource - initial API and implementation
+ *  Cloudsmith Inc. - converted into expression based query
 ******************************************************************************/
 package org.eclipse.equinox.internal.p2.metadata.query;
 
-import java.util.*;
+import org.eclipse.equinox.internal.p2.metadata.expression.ContextExpression;
+import org.eclipse.equinox.internal.p2.metadata.expression.ExpressionFactory;
 import org.eclipse.equinox.p2.metadata.IVersionedId;
-import org.eclipse.equinox.p2.metadata.index.IIndexProvider;
-import org.eclipse.equinox.p2.metadata.index.IQueryWithIndex;
-import org.eclipse.equinox.p2.query.*;
+import org.eclipse.equinox.p2.metadata.expression.*;
+import org.eclipse.equinox.p2.metadata.query.ExpressionContextQuery;
+import org.eclipse.equinox.p2.query.IQuery;
 
 /**
  * This query returns the latest version for each unique VersionedID.  
  * All other elements are discarded.
  */
-public class LatestIUVersionQuery<T extends IVersionedId> extends ContextQuery<T> implements IQueryWithIndex<T> {
+public class LatestIUVersionQuery<T extends IVersionedId> extends ExpressionContextQuery<T> {
 
-	private final IQuery<T> query;
-
-	public LatestIUVersionQuery() {
-		this.query = null;
-	}
-
-	public LatestIUVersionQuery(IQuery<T> query) {
-		this.query = query;
+	private static <T> IContextExpression<T> createLatestExpression(IQuery<T> query) {
+		ContextExpression<T> ctxExpr = (ContextExpression<T>) createExpression(query);
+		IExpressionFactory factory = ExpressionUtil.getFactory();
+		return factory.contextExpression(factory.latest(ctxExpr.operand), ctxExpr.getParameters());
 	}
 
-	/**
-	 * Performs the LatestIUVersionQuery
-	 */
-	public IQueryResult<T> perform(Iterator<T> iterator) {
-		if (query != null)
-			iterator = query.perform(iterator).iterator();
-		return latest(iterator);
+	private static IContextExpression<?> createLatestExpression() {
+		IExpressionFactory factory = ExpressionUtil.getFactory();
+		return factory.contextExpression(factory.latest(ExpressionFactory.EVERYTHING));
 	}
 
-	public IQueryResult<T> perform(IIndexProvider<T> indexProvider) {
-		Iterator<T> iterator;
-		if (query != null) {
-			if (query instanceof IQueryWithIndex<?>)
-				iterator = ((IQueryWithIndex<T>) query).perform(indexProvider).iterator();
-			else
-				iterator = query.perform(indexProvider.everything()).iterator();
-		} else
-			iterator = indexProvider.everything();
-		return latest(iterator);
+	@SuppressWarnings("unchecked")
+	public LatestIUVersionQuery() {
+		super((Class<? extends T>) IVersionedId.class, createLatestExpression());
 	}
 
-	private IQueryResult<T> latest(Iterator<T> iterator) {
-		HashMap<String, T> greatestIUVersion = new HashMap<String, T>();
-		while (iterator.hasNext()) {
-			T versionedID = iterator.next();
-			if (greatestIUVersion.containsKey(versionedID.getId())) {
-				T currentIU = greatestIUVersion.get(versionedID.getId());
-				if (currentIU.getVersion().compareTo(versionedID.getVersion()) < 0)
-					greatestIUVersion.put(versionedID.getId(), versionedID);
-			} else
-				greatestIUVersion.put(versionedID.getId(), versionedID);
-		}
-
-		Collection<T> values = greatestIUVersion.values();
-		Iterator<T> valuesIterator = values.iterator();
-		boolean continueGather = true;
-
-		Collector<T> result = new Collector<T>();
-		while (valuesIterator.hasNext() && continueGather) {
-			T nextIU = valuesIterator.next();
-			continueGather = result.accept(nextIU);
-		}
-		return result;
+	public LatestIUVersionQuery(IQuery<T> query) {
+		super(getElementClass(query), createLatestExpression(query));
 	}
 }
diff --git a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/query/UpdateQuery.java b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/query/UpdateQuery.java
index 61f97c47f..d27b230ad 100644
--- a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/query/UpdateQuery.java
+++ b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/query/UpdateQuery.java
@@ -6,38 +6,40 @@
  *  http://www.eclipse.org/legal/epl-v10.html
  * 
  *  Contributors:
- *      IBM Corporation - initial API and implementation
+ *     IBM Corporation - initial API and implementation
+ *     Cloudsmith Inc. - converted into expression based query
  *******************************************************************************/
 package org.eclipse.equinox.internal.p2.metadata.query;
 
-import org.eclipse.equinox.p2.metadata.*;
-import org.eclipse.equinox.p2.query.MatchQuery;
+import org.eclipse.equinox.p2.metadata.IInstallableUnit;
+import org.eclipse.equinox.p2.metadata.IInstallableUnitPatch;
+import org.eclipse.equinox.p2.metadata.expression.*;
+import org.eclipse.equinox.p2.metadata.query.ExpressionQuery;
 
 /**
  * A query that finds all IUs that are considered an "Update" of the 
  * specified IU.  
  */
-public final class UpdateQuery extends MatchQuery<IInstallableUnit> {
-	private IInstallableUnit updateFrom;
+public final class UpdateQuery extends ExpressionQuery<IInstallableUnit> {
+	private static final IExpression expr1;
+	private static final IExpression expr2;
 
-	public UpdateQuery(IInstallableUnit updateFrom) {
-		this.updateFrom = updateFrom;
+	static {
+		IExpressionParser parser = ExpressionUtil.getParser();
+
+		// This expression is used in case the updateFrom is an IInstallableUnitPatch
+		//
+		expr1 = parser.parse("$0 ~= updateDescriptor && ($0.id != id || $0.version < version)"); //$NON-NLS-1$
+
+		// When updateFrom is not an IInstallableUnitPatch, we need to do one of two things depending
+		// on if the current item is an InstallableUnitPatch or not.
+		//
+		expr2 = parser.parse("this ~= class('org.eclipse.equinox.p2.metadata.IInstallableUnitPatch')" + // //$NON-NLS-1$
+				"? $0 ~= lifeCycle" + // //$NON-NLS-1$
+				": $0 ~= updateDescriptor && ($0.id != id || $0.version < version)"); //$NON-NLS-1$
 	}
 
-	public boolean isMatch(IInstallableUnit candidate) {
-		if (candidate instanceof IInstallableUnitPatch && !(updateFrom instanceof IInstallableUnitPatch)) {
-			IInstallableUnitPatch potentialPatch = (IInstallableUnitPatch) candidate;
-			IRequirement lifeCycle = potentialPatch.getLifeCycle();
-			if (lifeCycle == null)
-				return false;
-			return updateFrom.satisfies(lifeCycle);
-		}
-		IUpdateDescriptor descriptor = candidate.getUpdateDescriptor();
-		if (descriptor != null && descriptor.isUpdateOf(updateFrom)) {
-			if (!updateFrom.getId().equals(candidate.getId()))
-				return true;
-			return updateFrom.getVersion().compareTo(candidate.getVersion()) < 0;
-		}
-		return false;
+	public UpdateQuery(IInstallableUnit updateFrom) {
+		super(IInstallableUnit.class, ExpressionUtil.getFactory().matchExpression(updateFrom instanceof IInstallableUnitPatch ? expr1 : expr2, updateFrom, IInstallableUnitPatch.class));
 	}
 }
diff --git a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/expression/IExpressionFactory.java b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/expression/IExpressionFactory.java
index 1206e79ec..a86891b94 100644
--- a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/expression/IExpressionFactory.java
+++ b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/expression/IExpressionFactory.java
@@ -11,6 +11,7 @@
 package org.eclipse.equinox.p2.metadata.expression;
 
 import java.util.List;
+import org.eclipse.equinox.p2.metadata.IVersionedId;
 import org.eclipse.equinox.p2.query.IQuery;
 
 /**
@@ -139,6 +140,15 @@ public interface IExpressionFactory {
 	IExpression lambda(IExpression variable, IExpression body);
 
 	/**
+	 * Create an expression that yields a new collection consisting of the latest version of
+	 * the elements of the <code>collection</code>. Each element in <code>collection</code>
+	 * must implement the {@link IVersionedId} interface.
+	 * @param collection The collection providing the versioned elements
+	 * @return A collection expression
+	 */
+	IExpression latest(IExpression collection);
+
+	/**
 	 * Create an expression that tests if <code>lhs</code> is less than <code>rhs</code>.
 	 * @param lhs The left hand side value.
 	 * @param rhs The right hand side value.
diff --git a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/CategoryMemberQuery.java b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/CategoryMemberQuery.java
index bb11a3ef0..d2d6b09c2 100644
--- a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/CategoryMemberQuery.java
+++ b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/CategoryMemberQuery.java
@@ -7,6 +7,7 @@
  * 
  *  Contributors:
  *     IBM Corporation - initial API and implementation
+ *     Cloudsmith Inc. - converted into expression based query
  *******************************************************************************/
 package org.eclipse.equinox.p2.metadata.query;
 
diff --git a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/CategoryQuery.java b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/CategoryQuery.java
index f93fbb4ab..65f6f5f1e 100644
--- a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/CategoryQuery.java
+++ b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/CategoryQuery.java
@@ -7,6 +7,7 @@
  * 
  *  Contributors:
  *     IBM Corporation - initial API and implementation
+ *     Cloudsmith Inc. - converted into expression based query
  *******************************************************************************/
 package org.eclipse.equinox.p2.metadata.query;
 
diff --git a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/ExpressionContextQuery.java b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/ExpressionContextQuery.java
index 11271b470..d02ac366f 100644
--- a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/ExpressionContextQuery.java
+++ b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/ExpressionContextQuery.java
@@ -11,13 +11,12 @@
 package org.eclipse.equinox.p2.metadata.query;
 
 import java.util.Iterator;
-import org.eclipse.equinox.internal.p2.metadata.expression.QueryResult;
+import org.eclipse.equinox.internal.p2.metadata.expression.*;
 import org.eclipse.equinox.p2.metadata.IInstallableUnit;
 import org.eclipse.equinox.p2.metadata.expression.*;
 import org.eclipse.equinox.p2.metadata.index.IIndexProvider;
 import org.eclipse.equinox.p2.metadata.index.IQueryWithIndex;
-import org.eclipse.equinox.p2.query.ContextQuery;
-import org.eclipse.equinox.p2.query.IQueryResult;
+import org.eclipse.equinox.p2.query.*;
 
 /**
  * A query that evaluates using an iterator as input and produces a new iterator.
@@ -58,4 +57,39 @@ public class ExpressionContextQuery<T> extends ContextQuery<T> implements IQuery
 	public IContextExpression<T> getExpression() {
 		return expression;
 	}
+
+	protected static <T> Class<? extends T> getElementClass(IQuery<T> query) {
+		@SuppressWarnings("unchecked")
+		Class<? extends T> elementClass = (Class<T>) Object.class;
+		if (query instanceof ExpressionQuery<?>)
+			elementClass = ((ExpressionQuery<T>) query).getMatchingClass();
+		else if (query instanceof ExpressionContextQuery<?>)
+			elementClass = ((ExpressionContextQuery<T>) query).getElementClass();
+		return elementClass;
+	}
+
+	protected static <T> IContextExpression<T> createExpression(IQuery<T> query) {
+		IExpressionFactory factory = ExpressionUtil.getFactory();
+		IExpression expr = query.getExpression();
+		Object[] parameters;
+		if (expr == null) {
+			expr = factory.toExpression(query);
+			if (query instanceof IMatchQuery<?>)
+				expr = factory.select(ExpressionFactory.EVERYTHING, factory.lambda(ExpressionFactory.THIS, expr));
+			parameters = new Object[0];
+		} else {
+			if (expr instanceof MatchExpression<?>) {
+				MatchExpression<?> matchExpr = (MatchExpression<?>) expr;
+				parameters = matchExpr.getParameters();
+				expr = factory.select(ExpressionFactory.EVERYTHING, factory.lambda(ExpressionFactory.THIS, matchExpr.operand));
+			} else if (expr instanceof ContextExpression<?>) {
+				ContextExpression<?> contextExpr = (ContextExpression<?>) expr;
+				parameters = contextExpr.getParameters();
+				expr = contextExpr.operand;
+			} else
+				parameters = new Object[0];
+		}
+		return factory.contextExpression(expr, parameters);
+	}
+
 }
diff --git a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/FragmentQuery.java b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/FragmentQuery.java
index de04066a3..22dfc2ef4 100644
--- a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/FragmentQuery.java
+++ b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/FragmentQuery.java
@@ -7,6 +7,7 @@
  * 
  *  Contributors:
  *     IBM Corporation - initial API and implementation
+ *     Cloudsmith Inc. - converted into expression based query
  *******************************************************************************/
 package org.eclipse.equinox.p2.metadata.query;
 
diff --git a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/GroupQuery.java b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/GroupQuery.java
index 729920902..d1035cf20 100644
--- a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/GroupQuery.java
+++ b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/GroupQuery.java
@@ -7,6 +7,7 @@
  * 
  *  Contributors:
  *     IBM Corporation - initial API and implementation
+ *     Cloudsmith Inc. - converted into expression based query
  *******************************************************************************/
 package org.eclipse.equinox.p2.metadata.query;
 
diff --git a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/InstallableUnitQuery.java b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/InstallableUnitQuery.java
index 42f5c9915..33b8e0bb5 100644
--- a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/InstallableUnitQuery.java
+++ b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/InstallableUnitQuery.java
@@ -7,6 +7,7 @@
  * 
  *  Contributors:
  *     IBM Corporation - initial API and implementation
+ *     Cloudsmith Inc. - converted into expression based query
  *******************************************************************************/
 package org.eclipse.equinox.p2.metadata.query;
 
diff --git a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/PatchQuery.java b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/PatchQuery.java
index e341d8efc..3217a755d 100644
--- a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/PatchQuery.java
+++ b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/query/PatchQuery.java
@@ -7,6 +7,7 @@
  * 
  *  Contributors:
  *     IBM Corporation - initial API and implementation
+ *     Cloudsmith Inc. - converted into expression based query
  *******************************************************************************/
 package org.eclipse.equinox.p2.metadata.query;
 
diff --git a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/query/CompoundQuery.java b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/query/CompoundQuery.java
index 12c873329..69e2170ff 100644
--- a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/query/CompoundQuery.java
+++ b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/query/CompoundQuery.java
@@ -8,6 +8,7 @@
  * Contributors:
  *     IBM Corporation - initial API and implementation
  *     EclipseSource - ongoing development
+ *     Cloudsmith Inc. - added index capabilities
  *******************************************************************************/
 package org.eclipse.equinox.p2.query;
 
diff --git a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/query/LimitQuery.java b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/query/LimitQuery.java
index d4b0d01a1..21e429841 100644
--- a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/query/LimitQuery.java
+++ b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/query/LimitQuery.java
@@ -6,13 +6,13 @@
 *
 * Contributors:
 *   EclipseSource - initial API and implementation
+*   Cloudsmith Inc. - converted into expression based query
 ******************************************************************************/
 package org.eclipse.equinox.p2.query;
 
-import org.eclipse.equinox.internal.p2.metadata.expression.*;
+import org.eclipse.equinox.internal.p2.metadata.expression.ContextExpression;
 import org.eclipse.equinox.p2.metadata.expression.*;
 import org.eclipse.equinox.p2.metadata.query.ExpressionContextQuery;
-import org.eclipse.equinox.p2.metadata.query.ExpressionQuery;
 
 /**
  * A limit query can be used to limit the number of query results returned.  Once
@@ -21,41 +21,13 @@ import org.eclipse.equinox.p2.metadata.query.ExpressionQuery;
  */
 public class LimitQuery<T> extends ExpressionContextQuery<T> {
 
-	private static <T> Class<? extends T> getElementClass(IQuery<T> query) {
-		@SuppressWarnings("unchecked")
-		Class<? extends T> elementClass = (Class<T>) Object.class;
-		if (query instanceof ExpressionQuery<?>)
-			elementClass = ((ExpressionQuery<T>) query).getMatchingClass();
-		else if (query instanceof ExpressionContextQuery<?>)
-			elementClass = ((ExpressionContextQuery<T>) query).getElementClass();
-		return elementClass;
-	}
-
-	private static <T> IContextExpression<T> createExpression(IQuery<T> query, int limit) {
+	private static <T> IContextExpression<T> createLimitExpression(IQuery<T> query, int limit) {
+		ContextExpression<T> ctxExpr = (ContextExpression<T>) createExpression(query);
 		IExpressionFactory factory = ExpressionUtil.getFactory();
-		IExpression expr = query.getExpression();
-		Object[] parameters;
-		if (expr == null) {
-			expr = factory.toExpression(query);
-			if (query instanceof IMatchQuery<?>)
-				expr = factory.select(ExpressionFactory.EVERYTHING, factory.lambda(ExpressionFactory.THIS, expr));
-			parameters = new Object[0];
-		} else {
-			if (expr instanceof MatchExpression<?>) {
-				MatchExpression<?> matchExpr = (MatchExpression<?>) expr;
-				parameters = matchExpr.getParameters();
-				expr = factory.select(ExpressionFactory.EVERYTHING, factory.lambda(ExpressionFactory.THIS, matchExpr.operand));
-			} else if (expr instanceof ContextExpression<?>) {
-				ContextExpression<?> contextExpr = (ContextExpression<?>) expr;
-				parameters = contextExpr.getParameters();
-				expr = contextExpr.operand;
-			} else
-				parameters = new Object[0];
-		}
-		return factory.contextExpression(factory.limit(expr, limit), parameters);
+		return factory.contextExpression(factory.limit(ctxExpr.operand, limit), ctxExpr.getParameters());
 	}
 
 	public LimitQuery(IQuery<T> query, int limit) {
-		super(getElementClass(query), createExpression(query, limit));
+		super(getElementClass(query), createLimitExpression(query, limit));
 	}
 }
diff --git a/bundles/org.eclipse.equinox.p2.ql/src/org/eclipse/equinox/p2/ql/IQLFactory.java b/bundles/org.eclipse.equinox.p2.ql/src/org/eclipse/equinox/p2/ql/IQLFactory.java
index 5a1544ae7..8bb69d055 100644
--- a/bundles/org.eclipse.equinox.p2.ql/src/org/eclipse/equinox/p2/ql/IQLFactory.java
+++ b/bundles/org.eclipse.equinox.p2.ql/src/org/eclipse/equinox/p2/ql/IQLFactory.java
@@ -11,7 +11,6 @@
 package org.eclipse.equinox.p2.ql;
 
 import java.util.Map;
-import org.eclipse.equinox.p2.metadata.IVersionedId;
 import org.eclipse.equinox.p2.metadata.expression.IExpression;
 import org.eclipse.equinox.p2.metadata.expression.IExpressionFactory;
 
@@ -107,15 +106,6 @@ public interface IQLFactory extends IExpressionFactory {
 	IExpression lambda(IExpression variable, IExpression[] initialAssignments, IExpression body);
 
 	/**
-	 * Create an expression that yields a new collection consisting of the latest version of
-	 * the elements of the <code>collection</code>. Each element in <code>collection</code>
-	 * must implement the {@link IVersionedId} interface.
-	 * @param collection The collection providing the versioned elements
-	 * @return A collection expression
-	 */
-	IExpression latest(IExpression collection);
-
-	/**
 	 * Creates a member call expression.
 	 * @param target The target for the member call
 	 * @param name The name of the member
diff --git a/bundles/org.eclipse.equinox.p2.ql/src/org/eclipse/equinox/p2/ql/QLQuery.java b/bundles/org.eclipse.equinox.p2.ql/src/org/eclipse/equinox/p2/ql/QLQuery.java
deleted file mode 100644
index 9987cdc7b..000000000
--- a/bundles/org.eclipse.equinox.p2.ql/src/org/eclipse/equinox/p2/ql/QLQuery.java
+++ /dev/null
@@ -1,35 +0,0 @@
-/*******************************************************************************
- * Copyright (c) 2009 Cloudsmith Inc. and others.
- * All rights reserved. This program and the accompanying materials
- * are made available under the terms of the Eclipse Public License v1.0
- * which accompanies this distribution, and is available at
- * http://www.eclipse.org/legal/epl-v10.html
- *
- * Contributors:
- *     Cloudsmith Inc. - initial API and implementation
- *******************************************************************************/
-package org.eclipse.equinox.p2.ql;
-
-import java.util.Locale;
-import org.eclipse.equinox.p2.query.IQuery;
-
-/**
- * An IQuery 'context query' implementation that is based on the p2 query language.
- */
-public abstract class QLQuery<T> implements IQuery<T> {
-	final Class<T> elementClass;
-	private Locale locale;
-
-	protected QLQuery(Class<T> elementClass) {
-		this.elementClass = elementClass;
-	}
-
-	public Locale getLocale() {
-		return locale == null ? Locale.getDefault() : locale;
-	}
-
-	public void setLocale(Locale locale) {
-		this.locale = locale;
-	}
-
-}
diff --git a/bundles/org.eclipse.equinox.p2.repository.tools/src_ant/org/eclipse/equinox/p2/internal/repository/tools/tasks/ArtifactDescription.java b/bundles/org.eclipse.equinox.p2.repository.tools/src_ant/org/eclipse/equinox/p2/internal/repository/tools/tasks/ArtifactDescription.java
index 09d09b7e2..ed430728d 100644
--- a/bundles/org.eclipse.equinox.p2.repository.tools/src_ant/org/eclipse/equinox/p2/internal/repository/tools/tasks/ArtifactDescription.java
+++ b/bundles/org.eclipse.equinox.p2.repository.tools/src_ant/org/eclipse/equinox/p2/internal/repository/tools/tasks/ArtifactDescription.java
@@ -1,6 +1,7 @@
 package org.eclipse.equinox.p2.internal.repository.tools.tasks;
 
-import java.util.Properties;
+import java.util.HashMap;
+import java.util.Map;
 import org.apache.tools.ant.types.DataType;
 import org.apache.tools.ant.types.Parameter;
 import org.eclipse.equinox.p2.metadata.*;
@@ -13,7 +14,7 @@ public class ArtifactDescription extends DataType {
 	private String id = null;
 	private String version = null;
 	private String range = null;
-	private Properties properties = null;
+	private Map<String, String> properties = null;
 
 	public void setClassifier(String classifier) {
 		this.classifier = classifier;
@@ -33,7 +34,7 @@ public class ArtifactDescription extends DataType {
 
 	public void addConfiguredProperty(Parameter property) {
 		if (properties == null)
-			properties = new Properties();
+			properties = new HashMap<String, String>();
 
 		properties.put(property.getName(), property.getValue());
 	}
@@ -69,9 +70,6 @@ public class ArtifactDescription extends DataType {
 			Version keyVersion = Version.parseVersion(version);
 			keyRange = new VersionRange(keyVersion, true, keyVersion, true);
 		}
-
-		ArtifactDescriptorQuery query = new ArtifactDescriptorQuery(id, keyRange, null);
-		query.setProperties(properties);
-		return query;
+		return new ArtifactDescriptorQuery(id, keyRange, null, properties);
 	}
 }
diff --git a/bundles/org.eclipse.equinox.p2.repository/src/org/eclipse/equinox/p2/repository/artifact/ArtifactDescriptorQuery.java b/bundles/org.eclipse.equinox.p2.repository/src/org/eclipse/equinox/p2/repository/artifact/ArtifactDescriptorQuery.java
index 9d660400e..0dee9e4bb 100644
--- a/bundles/org.eclipse.equinox.p2.repository/src/org/eclipse/equinox/p2/repository/artifact/ArtifactDescriptorQuery.java
+++ b/bundles/org.eclipse.equinox.p2.repository/src/org/eclipse/equinox/p2/repository/artifact/ArtifactDescriptorQuery.java
@@ -7,15 +7,16 @@
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
+ *     Cloudsmith Inc. - converted into expression based query
  *******************************************************************************/
 
 package org.eclipse.equinox.p2.repository.artifact;
 
-import java.util.Iterator;
-import java.util.Properties;
+import java.util.*;
+import org.eclipse.equinox.internal.p2.core.helpers.CollectionUtils;
 import org.eclipse.equinox.p2.metadata.VersionRange;
-import org.eclipse.equinox.p2.query.MatchQuery;
-import org.eclipse.equinox.p2.repository.artifact.spi.ArtifactDescriptor;
+import org.eclipse.equinox.p2.metadata.expression.*;
+import org.eclipse.equinox.p2.metadata.query.ExpressionQuery;
 
 /**
  * A general purpose query for matching {@link IArtifactDescriptor} instances
@@ -23,112 +24,65 @@ import org.eclipse.equinox.p2.repository.artifact.spi.ArtifactDescriptor;
  * 
  * @since 2.0
  */
-public class ArtifactDescriptorQuery extends MatchQuery<IArtifactDescriptor> {
+public class ArtifactDescriptorQuery extends ExpressionQuery<IArtifactDescriptor> {
+
+	private static final IExpression descriptorMatch = ExpressionUtil.parse(//
+			"artifactKey.id == $0 && artifactKey.version ~= $1 && ($2.empty || $2.all(x | properties[x.key] == x.value))"); //$NON-NLS-1$
+
+	private static IMatchExpression<IArtifactDescriptor> createExpression(String id, VersionRange range, String format, Map<String, String> properties) {
+		if (range == null)
+			range = VersionRange.emptyRange;
+		if (format != null) {
+			if (properties == null || properties.isEmpty())
+				properties = Collections.singletonMap(IArtifactDescriptor.FORMAT, format);
+			else {
+				properties = new HashMap<String, String>(properties);
+				properties.put(IArtifactDescriptor.FORMAT, format);
+			}
+		} else if (properties == null)
+			properties = CollectionUtils.emptyMap();
+
+		IExpressionFactory factory = ExpressionUtil.getFactory();
+		return factory.<IArtifactDescriptor> matchExpression(descriptorMatch, id, range, properties);
+	}
 
 	/**
 	 * A singleton query that will match all instances of {@link IArtifactDescriptor}.
 	 */
 	public static final ArtifactDescriptorQuery ALL_DESCRIPTORS = new ArtifactDescriptorQuery();
 
-	private ArtifactDescriptor descriptor = null;
-	private String format = null;
-	private String id = null;
-	private Properties properties = null;
-	private VersionRange range = null;
-	private IArtifactRepository repository = null;
-
 	/**
 	 * Clients must use {@link #ALL_DESCRIPTORS}.
 	 */
 	private ArtifactDescriptorQuery() {
 		//matches everything
+		super(IArtifactDescriptor.class, ExpressionUtil.TRUE_EXPRESSION);
 	}
 
 	/**
-	 * The query will match candidate descriptors where:
-	 * <pre>
-	 *     new ArtifactDescriptor(descriptor).equals(new ArtifactDescriptor(candidate))
-	 * </pre>
-	 * @param descriptor The descriptor to match
-	 */
-	public ArtifactDescriptorQuery(IArtifactDescriptor descriptor) {
-		this.descriptor = (descriptor.getClass() == ArtifactDescriptor.class) ? (ArtifactDescriptor) descriptor : new ArtifactDescriptor(descriptor);
-	}
-
-	/**
-	 * The query will match descriptors with the given id, version and format
-	 * If any parameter is null, that attribute will be ignored.
-	 * 
-	 * @param id the descriptor id to match, or <code>null</code> to match any id
+	 * The query will match descriptors with the given <code>id</code>, <code>versionRange</code>
+	 * and <code>format</code>
+	 * @param id the descriptor id to match. Can not be <code>null</code>
 	 * @param versionRange the descriptor version range to match or <code>null</code> to match
 	 * any version range
 	 * @param format the descriptor {@link IArtifactDescriptor#FORMAT} value to match, or <code>null</code> to
 	 * match any descriptor format
 	 */
 	public ArtifactDescriptorQuery(String id, VersionRange versionRange, String format) {
-		this(id, versionRange, format, null);
+		super(IArtifactDescriptor.class, createExpression(id, versionRange, format, null));
 	}
 
 	/**
-	 * The query will match descriptors with the given id, version range, format and repository
-	 * if any parameter is null, that attribute will be ignored.
-	 * 
-	 * @param id the descriptor id to match, or <code>null</code> to match any id
+	 * The query will match descriptors with the given <code>id</code>, <code>versionRange</code>,
+	 * <code>format</code>, and <code>properties</code>.
+	 * @param id the descriptor id to match. Can not be <code>null</code>
 	 * @param versionRange the descriptor version range to match or <code>null</code> to match
 	 * any version range
 	 * @param format the descriptor {@link IArtifactDescriptor#FORMAT} value to match, or <code>null</code> to
 	 * match any descriptor format
-	 * @param repository The repository of the descriptor to match, or <code>null</code>
-	 * to match descriptors from any repository
-	 */
-	public ArtifactDescriptorQuery(String id, VersionRange versionRange, String format, IArtifactRepository repository) {
-		this.id = id;
-		this.range = versionRange;
-		this.format = format;
-		this.repository = repository;
-	}
-
-	/*(non-Javadoc)
-	 * @see org.eclipse.equinox.p2.query.MatchQuery#isMatch(java.lang.Object)
-	 */
-	public boolean isMatch(IArtifactDescriptor candidate) {
-		if (descriptor != null)
-			return matchDescriptor(candidate);
-
-		if (id != null && !id.equals(candidate.getArtifactKey().getId()))
-			return false;
-
-		if (range != null && !range.isIncluded(candidate.getArtifactKey().getVersion()))
-			return false;
-
-		if (format != null && !format.equals(candidate.getProperty(IArtifactDescriptor.FORMAT)))
-			return false;
-
-		if (repository != null && repository != candidate.getRepository())
-			return false;
-
-		if (properties != null) {
-			for (Iterator<Object> iterator = properties.keySet().iterator(); iterator.hasNext();) {
-				String key = (String) iterator.next();
-				String value = properties.getProperty(key);
-				if (value != null && !value.equals(candidate.getProperty(key)))
-					return false;
-			}
-		}
-		return true;
-	}
-
-	private boolean matchDescriptor(IArtifactDescriptor candidate) {
-		ArtifactDescriptor candidateDescriptor = (candidate.getClass() == ArtifactDescriptor.class) ? (ArtifactDescriptor) candidate : new ArtifactDescriptor(candidate);
-		return descriptor.equals(candidateDescriptor);
-	}
-
-	/**
-	 * Sets the properties that this query should match against. This query will only match
-	 * descriptors that have property keys and values matching those provided here.
 	 * @param properties The properties to query for
 	 */
-	public void setProperties(Properties properties) {
-		this.properties = properties;
+	public ArtifactDescriptorQuery(String id, VersionRange versionRange, String format, Map<String, String> properties) {
+		super(IArtifactDescriptor.class, createExpression(id, versionRange, format, properties));
 	}
 }
diff --git a/bundles/org.eclipse.equinox.p2.repository/src/org/eclipse/equinox/p2/repository/artifact/ArtifactKeyQuery.java b/bundles/org.eclipse.equinox.p2.repository/src/org/eclipse/equinox/p2/repository/artifact/ArtifactKeyQuery.java
index 4b8bd8686..8758da2d7 100644
--- a/bundles/org.eclipse.equinox.p2.repository/src/org/eclipse/equinox/p2/repository/artifact/ArtifactKeyQuery.java
+++ b/bundles/org.eclipse.equinox.p2.repository/src/org/eclipse/equinox/p2/repository/artifact/ArtifactKeyQuery.java
@@ -7,6 +7,7 @@
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
+ *     Cloudsmith Inc. - converted into expression based query
  *******************************************************************************/
 
 package org.eclipse.equinox.p2.repository.artifact;
diff --git a/bundles/org.eclipse.equinox.p2.repository/src/org/eclipse/equinox/p2/repository/artifact/spi/ArtifactDescriptor.java b/bundles/org.eclipse.equinox.p2.repository/src/org/eclipse/equinox/p2/repository/artifact/spi/ArtifactDescriptor.java
index 68e51fb66..350e17b19 100644
--- a/bundles/org.eclipse.equinox.p2.repository/src/org/eclipse/equinox/p2/repository/artifact/spi/ArtifactDescriptor.java
+++ b/bundles/org.eclipse.equinox.p2.repository/src/org/eclipse/equinox/p2/repository/artifact/spi/ArtifactDescriptor.java
@@ -7,6 +7,7 @@
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
+ *     Cloudsmith Inc. - IMemberProvider access.
  *******************************************************************************/
 package org.eclipse.equinox.p2.repository.artifact.spi;
 
@@ -14,13 +15,19 @@ import java.util.Arrays;
 import java.util.Map;
 import org.eclipse.equinox.internal.p2.core.helpers.OrderedProperties;
 import org.eclipse.equinox.p2.metadata.IArtifactKey;
+import org.eclipse.equinox.p2.metadata.expression.IMemberProvider;
 import org.eclipse.equinox.p2.repository.artifact.*;
 
 /**
  * This represents information about a given artifact stored on a particular byte server.
  * @since 2.0
  */
-public class ArtifactDescriptor implements IArtifactDescriptor {
+public class ArtifactDescriptor implements IArtifactDescriptor, IMemberProvider {
+	public static final String MEMBER_ARTIFACT_KEY = "artifactKey"; //$NON-NLS-1$
+	public static final String MEMBER_PROCESSING_STEPS = "processingSteps"; //$NON-NLS-1$
+	public static final String MEMBER_PROPERTIES = "properties"; //$NON-NLS-1$
+	public static final String MEMBER_REPOSITORY = "repository"; //$NON-NLS-1$
+
 	private static final IProcessingStepDescriptor[] EMPTY_STEPS = new ProcessingStepDescriptor[0];
 
 	protected IArtifactKey key; // The key associated with this artifact
@@ -149,4 +156,20 @@ public class ArtifactDescriptor implements IArtifactDescriptor {
 		return format + ": " + key.toString(); //$NON-NLS-1$
 	}
 
+	public Object getMember(String memberName) {
+		if (memberName == MEMBER_ARTIFACT_KEY)
+			return key;
+
+		if (memberName == MEMBER_PROPERTIES)
+			return properties;
+
+		if (memberName == MEMBER_PROCESSING_STEPS)
+			return processingSteps;
+
+		if (memberName == MEMBER_REPOSITORY)
+			return repository;
+
+		throw new IllegalArgumentException("No such member: " + memberName); //$NON-NLS-1$
+	}
+
 }
diff --git a/bundles/org.eclipse.equinox.p2.tests/src/org/eclipse/equinox/p2/tests/artifact/repository/SimpleArtifactRepositoryTest.java b/bundles/org.eclipse.equinox.p2.tests/src/org/eclipse/equinox/p2/tests/artifact/repository/SimpleArtifactRepositoryTest.java
index 75e0082ef..369665e57 100644
--- a/bundles/org.eclipse.equinox.p2.tests/src/org/eclipse/equinox/p2/tests/artifact/repository/SimpleArtifactRepositoryTest.java
+++ b/bundles/org.eclipse.equinox.p2.tests/src/org/eclipse/equinox/p2/tests/artifact/repository/SimpleArtifactRepositoryTest.java
@@ -367,11 +367,11 @@ public class SimpleArtifactRepositoryTest extends AbstractProvisioningTest {
 		IQueryResult<IArtifactDescriptor> result = descQueryable.query(new ArtifactDescriptorQuery("a", null, null), null);
 		assertEquals(3, queryResultSize(result));
 
-		result = descQueryable.query(new ArtifactDescriptorQuery(null, new VersionRange("[2.0.0, 3.0.0)"), null), null);
+		result = descQueryable.query(new ArtifactDescriptorQuery("a", new VersionRange("[2.0.0, 3.0.0)"), null), null);
 		assertEquals(2, queryResultSize(result));
 		assertNotContains(result, d1);
 
-		result = descQueryable.query(new ArtifactDescriptorQuery(null, null, IArtifactDescriptor.FORMAT_PACKED), null);
+		result = descQueryable.query(new ArtifactDescriptorQuery("a", null, IArtifactDescriptor.FORMAT_PACKED), null);
 		assertEquals(1, queryResultSize(result));
 		IArtifactDescriptor resultDescriptor = result.iterator().next();
 		assertEquals(d3.getArtifactKey(), resultDescriptor.getArtifactKey());
diff --git a/bundles/org.eclipse.equinox.p2.touchpoint.eclipse/META-INF/MANIFEST.MF b/bundles/org.eclipse.equinox.p2.touchpoint.eclipse/META-INF/MANIFEST.MF
index 8f462754f..f95c89ad5 100644
--- a/bundles/org.eclipse.equinox.p2.touchpoint.eclipse/META-INF/MANIFEST.MF
+++ b/bundles/org.eclipse.equinox.p2.touchpoint.eclipse/META-INF/MANIFEST.MF
@@ -20,6 +20,7 @@ Import-Package: javax.xml.parsers,
  org.eclipse.equinox.p2.engine,
  org.eclipse.equinox.p2.engine.spi,
  org.eclipse.equinox.p2.metadata,
+ org.eclipse.equinox.p2.metadata.expression,
  org.eclipse.equinox.p2.metadata.query,
  org.eclipse.equinox.p2.planner,
  org.eclipse.equinox.p2.publisher;resolution:=optional,
diff --git a/bundles/org.eclipse.equinox.p2.touchpoint.eclipse/src/org/eclipse/equinox/p2/touchpoint/eclipse/query/OSGiBundleQuery.java b/bundles/org.eclipse.equinox.p2.touchpoint.eclipse/src/org/eclipse/equinox/p2/touchpoint/eclipse/query/OSGiBundleQuery.java
index cd143acde..ef4809413 100644
--- a/bundles/org.eclipse.equinox.p2.touchpoint.eclipse/src/org/eclipse/equinox/p2/touchpoint/eclipse/query/OSGiBundleQuery.java
+++ b/bundles/org.eclipse.equinox.p2.touchpoint.eclipse/src/org/eclipse/equinox/p2/touchpoint/eclipse/query/OSGiBundleQuery.java
@@ -6,26 +6,26 @@
  *  http://www.eclipse.org/legal/epl-v10.html
  * 
  *  Contributors:
- *      IBM Corporation - initial API and implementation
+ *     IBM Corporation - initial API and implementation
+ *     Cloudsmith Inc. - converted into expression based query
  *******************************************************************************/
 package org.eclipse.equinox.p2.touchpoint.eclipse.query;
 
-import java.util.Collection;
 import org.eclipse.equinox.p2.metadata.IInstallableUnit;
-import org.eclipse.equinox.p2.metadata.IProvidedCapability;
-import org.eclipse.equinox.p2.query.MatchQuery;
+import org.eclipse.equinox.p2.metadata.expression.ExpressionUtil;
+import org.eclipse.equinox.p2.metadata.expression.IMatchExpression;
+import org.eclipse.equinox.p2.metadata.query.ExpressionQuery;
 
 /**
  * A query matching every {@link IInstallableUnit} that describes an OSGi bundle. 
  * @since 2.0
  */
-public class OSGiBundleQuery extends MatchQuery<IInstallableUnit> {
+public class OSGiBundleQuery extends ExpressionQuery<IInstallableUnit> {
 
-	/* (non-Javadoc)
-	 * @see org.eclipse.equinox.p2.query.MatchQuery#isMatch(java.lang.Object)
-	 */
-	public boolean isMatch(IInstallableUnit candidate) {
-		return isOSGiBundle(candidate);
+	private static final IMatchExpression<IInstallableUnit> bundleTest = ExpressionUtil.getFactory().matchExpression(ExpressionUtil.parse("providedCapabilities.exists(p | p.namespace == 'osgi.bundle')")); //$NON-NLS-1$
+
+	public OSGiBundleQuery() {
+		super(IInstallableUnit.class, bundleTest);
 	}
 
 	/**
@@ -34,12 +34,6 @@ public class OSGiBundleQuery extends MatchQuery<IInstallableUnit> {
 	 * @return <tt>true</tt> if the parameter describes an OSGi bundle.
 	 */
 	public static boolean isOSGiBundle(IInstallableUnit iu) {
-		Collection<IProvidedCapability> provided = iu.getProvidedCapabilities();
-		for (IProvidedCapability capability : provided) {
-			if (capability.getNamespace().equals("osgi.bundle")) { //$NON-NLS-1$
-				return true;
-			}
-		}
-		return false;
+		return bundleTest.isMatch(iu);
 	}
 }
\ No newline at end of file
diff --git a/bundles/org.eclipse.equinox.p2.ui.sdk.scheduler/META-INF/MANIFEST.MF b/bundles/org.eclipse.equinox.p2.ui.sdk.scheduler/META-INF/MANIFEST.MF
index 743825dcf..cbca47dcd 100644
--- a/bundles/org.eclipse.equinox.p2.ui.sdk.scheduler/META-INF/MANIFEST.MF
+++ b/bundles/org.eclipse.equinox.p2.ui.sdk.scheduler/META-INF/MANIFEST.MF
@@ -21,6 +21,7 @@ Import-Package: com.ibm.icu.util;version="4.0.1",
  org.eclipse.equinox.internal.provisional.p2.updatechecker,
  org.eclipse.equinox.p2.core,
  org.eclipse.equinox.p2.engine,
+ org.eclipse.equinox.p2.engine.query,
  org.eclipse.equinox.p2.metadata,
  org.eclipse.equinox.p2.metadata.query,
  org.eclipse.equinox.p2.operations,
diff --git a/bundles/org.eclipse.equinox.p2.ui.sdk.scheduler/src/org/eclipse/equinox/internal/p2/ui/sdk/scheduler/AutomaticUpdateScheduler.java b/bundles/org.eclipse.equinox.p2.ui.sdk.scheduler/src/org/eclipse/equinox/internal/p2/ui/sdk/scheduler/AutomaticUpdateScheduler.java
index b422333d7..cfb42f3cc 100644
--- a/bundles/org.eclipse.equinox.p2.ui.sdk.scheduler/src/org/eclipse/equinox/internal/p2/ui/sdk/scheduler/AutomaticUpdateScheduler.java
+++ b/bundles/org.eclipse.equinox.p2.ui.sdk.scheduler/src/org/eclipse/equinox/internal/p2/ui/sdk/scheduler/AutomaticUpdateScheduler.java
@@ -18,9 +18,9 @@ import org.eclipse.equinox.internal.provisional.p2.updatechecker.*;
 import org.eclipse.equinox.p2.core.IProvisioningAgent;
 import org.eclipse.equinox.p2.engine.IProfile;
 import org.eclipse.equinox.p2.engine.IProfileRegistry;
+import org.eclipse.equinox.p2.engine.query.IUProfilePropertyQuery;
 import org.eclipse.equinox.p2.metadata.IInstallableUnit;
 import org.eclipse.equinox.p2.query.IQuery;
-import org.eclipse.equinox.p2.query.MatchQuery;
 import org.eclipse.jface.preference.IPreferenceStore;
 import org.eclipse.ui.IStartup;
 import org.eclipse.ui.statushandlers.StatusManager;
@@ -61,47 +61,6 @@ public class AutomaticUpdateScheduler implements IStartup {
 	}
 
 	/**
-	 * A query that searches for {@link IInstallableUnit} instances that have
-	 * a property associated with the specified profile, whose value matches the provided value.
-	 * Uses the profile id instead of the profile to reference the profile.
-	 * The profile instance is cached only during the duration of the query.
-	 * This query is used instead of IUProfilePropertyQuery because we pass
-	 * this query to the automatic update checker and it will be referenced during
-	 * the life of the platform.  
-	 */
-	private class IUProfilePropertyByIdQuery extends MatchQuery<IInstallableUnit> {
-		private final String propertyName;
-		private IProfile cachedProfile;
-
-		/**
-		 * Creates a new query on the given property name and value.
-		 */
-		public IUProfilePropertyByIdQuery(String propertyName) {
-			this.propertyName = propertyName;
-		}
-
-		private IProfile getProfile() {
-			if (cachedProfile == null) {
-				IProvisioningAgent agent = (IProvisioningAgent) ServiceHelper.getService(AutomaticUpdatePlugin.getContext(), IProvisioningAgent.SERVICE_NAME);
-				IProfileRegistry profileRegistry = (IProfileRegistry) agent.getService(IProfileRegistry.SERVICE_NAME);
-				if (profileRegistry != null)
-					cachedProfile = profileRegistry.getProfile(profileId);
-			}
-			return cachedProfile;
-		}
-
-		// overridden to release profile cache
-		public void postPerform() {
-			cachedProfile = null;
-		}
-
-		public boolean isMatch(IInstallableUnit candidate) {
-			IProfile profile = getProfile();
-			return profile != null && Boolean.valueOf(profile.getInstallableUnitProperty(candidate, propertyName)).booleanValue();
-		}
-	}
-
-	/**
 	 * The constructor.
 	 */
 	public AutomaticUpdateScheduler() {
@@ -170,7 +129,7 @@ public class AutomaticUpdateScheduler implements IStartup {
 	private IQuery<IInstallableUnit> getProfileQuery() {
 		// We specifically avoid using the default policy's root property so that we don't load all the
 		// p2 UI classes in doing so.  
-		return new IUProfilePropertyByIdQuery(IProfile.PROP_PROFILE_ROOT_IU);
+		return new IUProfilePropertyQuery(IProfile.PROP_PROFILE_ROOT_IU, Boolean.TRUE.toString());
 	}
 
 	private int getDay(IPreferenceStore pref) {
diff --git a/bundles/org.eclipse.equinox.p2.ui/src/org/eclipse/equinox/internal/p2/ui/QueryProvider.java b/bundles/org.eclipse.equinox.p2.ui/src/org/eclipse/equinox/internal/p2/ui/QueryProvider.java
index 46787ca15..4388af162 100644
--- a/bundles/org.eclipse.equinox.p2.ui/src/org/eclipse/equinox/internal/p2/ui/QueryProvider.java
+++ b/bundles/org.eclipse.equinox.p2.ui/src/org/eclipse/equinox/internal/p2/ui/QueryProvider.java
@@ -45,11 +45,7 @@ public class QueryProvider {
 	public static final int INSTALLED_IUS = 6;
 	public static final int AVAILABLE_ARTIFACTS = 7;
 
-	private IQuery<IInstallableUnit> allQuery = new MatchQuery<IInstallableUnit>() {
-		public boolean isMatch(IInstallableUnit candidate) {
-			return true;
-		}
-	};
+	private IQuery<IInstallableUnit> allQuery = new ExpressionQuery<IInstallableUnit>(IInstallableUnit.class, ExpressionQuery.MATCH_ALL_UNITS);
 
 	public QueryProvider(ProvisioningUI ui) {
 		this.ui = ui;
diff --git a/bundles/org.eclipse.equinox.p2.ui/src/org/eclipse/equinox/internal/p2/ui/query/RequiredIUsQuery.java b/bundles/org.eclipse.equinox.p2.ui/src/org/eclipse/equinox/internal/p2/ui/query/RequiredIUsQuery.java
index c8590c489..3037d86b5 100644
--- a/bundles/org.eclipse.equinox.p2.ui/src/org/eclipse/equinox/internal/p2/ui/query/RequiredIUsQuery.java
+++ b/bundles/org.eclipse.equinox.p2.ui/src/org/eclipse/equinox/internal/p2/ui/query/RequiredIUsQuery.java
@@ -7,13 +7,14 @@
  * 
  *  Contributors:
  *     IBM Corporation - initial API and implementation
+ *     Cloudsmith Inc. - converted into expression based query
  *******************************************************************************/
 package org.eclipse.equinox.internal.p2.ui.query;
 
-import java.util.Collection;
 import org.eclipse.equinox.p2.metadata.IInstallableUnit;
-import org.eclipse.equinox.p2.metadata.IRequirement;
-import org.eclipse.equinox.p2.query.MatchQuery;
+import org.eclipse.equinox.p2.metadata.expression.ExpressionUtil;
+import org.eclipse.equinox.p2.metadata.expression.IExpression;
+import org.eclipse.equinox.p2.metadata.query.ExpressionQuery;
 
 /**
 /**
@@ -27,9 +28,9 @@ import org.eclipse.equinox.p2.query.MatchQuery;
  * 
  * @since 2.0 
  */
-public class RequiredIUsQuery extends MatchQuery<IInstallableUnit> {
+public class RequiredIUsQuery extends ExpressionQuery<IInstallableUnit> {
 
-	private final Collection<IRequirement> required;
+	private static final IExpression expression = ExpressionUtil.parse("$0.exists(rc | this ~= rc)"); //$NON-NLS-1$
 
 	/**
 	 * Creates a new query that will return any IU that meets any
@@ -38,19 +39,6 @@ public class RequiredIUsQuery extends MatchQuery<IInstallableUnit> {
 	 * @param iu The IU whose requirements are to be checked
 	 */
 	public RequiredIUsQuery(IInstallableUnit iu) {
-		this.required = iu.getRequiredCapabilities();
-	}
-
-	/*
-	 * (non-Javadoc)
-	 * @see org.eclipse.equinox.internal.provisional.p2.metadata.query.MatchQuery#isMatch(java.lang.Object)
-	 */
-	public boolean isMatch(IInstallableUnit candidate) {
-		// meeting any requirement is sufficient to match the query.
-		for (IRequirement req : required) {
-			if (candidate.satisfies(req))
-				return true;
-		}
-		return false;
+		super(IInstallableUnit.class, ExpressionUtil.getFactory().matchExpression(expression, iu.getRequiredCapabilities()));
 	}
 }