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/*******************************************************************************
* Copyright (c) 2004-2012 Gabor Bergmann and Daniel Varro
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0 which is available at
* http://www.eclipse.org/legal/epl-v20.html.
*
* SPDX-License-Identifier: EPL-2.0
*******************************************************************************/
package tools.refinery.viatra.runtime.rete.index;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
import tools.refinery.viatra.runtime.matchers.tuple.TupleMask;
import tools.refinery.viatra.runtime.matchers.tuple.Tuples;
import tools.refinery.viatra.runtime.matchers.util.Direction;
import tools.refinery.viatra.runtime.rete.network.Node;
import tools.refinery.viatra.runtime.rete.network.ReteContainer;
import tools.refinery.viatra.runtime.rete.network.Supplier;
import tools.refinery.viatra.runtime.rete.network.communication.Timestamp;
/**
* Defines an abstract trivial indexer that projects the contents of some stateful node to the empty tuple, and can
* therefore save space. Can only exist in connection with a stateful store, and must be operated by another node (the
* active node). Do not attach parents directly!
*
* @author Gabor Bergmann
* @noimplement Rely on the provided implementations
* @noreference Use only via standard Node and Indexer interfaces
* @noinstantiate This class is not intended to be instantiated by clients.
*/
public abstract class NullIndexer extends SpecializedProjectionIndexer {
protected abstract Collection<Tuple> getTuples();
protected static final Tuple nullSignature = Tuples.staticArityFlatTupleOf();
protected static final Collection<Tuple> nullSingleton = Collections.singleton(nullSignature);
protected static final Collection<Tuple> emptySet = Collections.emptySet();
public NullIndexer(ReteContainer reteContainer, int tupleWidth, Supplier parent, Node activeNode,
List<ListenerSubscription> sharedSubscriptionList) {
super(reteContainer, TupleMask.linear(0, tupleWidth), parent, activeNode, sharedSubscriptionList);
}
@Override
public Collection<Tuple> get(Tuple signature) {
if (nullSignature.equals(signature))
return isEmpty() ? null : getTuples();
else
return null;
}
@Override
public Collection<Tuple> getSignatures() {
return isEmpty() ? emptySet : nullSingleton;
}
protected boolean isEmpty() {
return getTuples().isEmpty();
}
protected boolean isSingleElement() {
return getTuples().size() == 1;
}
@Override
public Iterator<Tuple> iterator() {
return getTuples().iterator();
}
@Override
public int getBucketCount() {
return getTuples().isEmpty() ? 0 : 1;
}
@Override
public void propagateToListener(IndexerListener listener, Direction direction, Tuple updateElement,
Timestamp timestamp) {
boolean radical = (direction == Direction.DELETE && isEmpty())
|| (direction == Direction.INSERT && isSingleElement());
listener.notifyIndexerUpdate(direction, updateElement, nullSignature, radical, timestamp);
}
}
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