1 files changed, 48 insertions, 0 deletions
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
new file mode 100644
index 000000000..fe79d9404
--- /dev/null
+++ b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/query/LatestIUVersionQuery.java
@@ -0,0 +1,48 @@
+/******************************************************************************* 
+* Copyright (c) 2009 EclipseSource 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:
+*   EclipseSource - initial API and implementation
+******************************************************************************/
+package org.eclipse.equinox.internal.p2.metadata.query;
+
+import java.util.*;
+import org.eclipse.equinox.p2.metadata.IVersionedId;
+import org.eclipse.equinox.p2.query.*;
+
+/**
+ * This query returns the latest version for each unique VersionedID.  
+ * All other elements are discarded.
+ */
+public class LatestIUVersionQuery<T extends IVersionedId> extends ContextQuery<T> {
+
+	/**
+	 * Performs the LatestIUVersionQuery
+	 */
+	public IQueryResult<T> perform(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;
+	}
+}