/*******************************************************************************
* Copyright (c) 2010 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.internal.p2.metadata.index;
import java.util.*;
import org.eclipse.equinox.internal.p2.core.helpers.CollectionUtils;
import org.eclipse.equinox.p2.metadata.expression.IEvaluationContext;
import org.eclipse.equinox.p2.metadata.expression.IExpression;
import org.eclipse.equinox.p2.metadata.index.IIndex;
public class CompoundIndex<T> implements IIndex<T> {
private final Collection<IIndex<T>> indexes;
public CompoundIndex(Collection<IIndex<T>> indexes) {
this.indexes = indexes;
}
public Iterator<T> getCandidates(IEvaluationContext ctx, IExpression variable, IExpression booleanExpr) {
Set<T> result = null;
for (IIndex<T> index : indexes) {
Iterator<T> indexResult = index.getCandidates(ctx, variable, booleanExpr);
if (indexResult == null)
return null;
if (indexResult.hasNext()) {
if (result == null)
result = new HashSet<T>();
do {
result.add(indexResult.next());
} while (indexResult.hasNext());
}
}
if (result == null)
result = CollectionUtils.emptySet();
return result.iterator();
}
}