IdentityIndexer.java

/*******************************************************************************
 * Copyright (c) 2004-2012 Gabor Bergmann and Daniel Varro
 * 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:
 *    Gabor Bergmann - initial API and implementation
 *******************************************************************************/

package org.eclipse.incquery.runtime.rete.index;

import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;

import org.eclipse.incquery.runtime.rete.network.Direction;
import org.eclipse.incquery.runtime.rete.network.Node;
import org.eclipse.incquery.runtime.rete.network.ReteContainer;
import org.eclipse.incquery.runtime.rete.network.Supplier;
import org.eclipse.incquery.runtime.rete.tuple.Tuple;
import org.eclipse.incquery.runtime.rete.tuple.TupleMask;

/**
 * Defines an abstract trivial indexer that identically projects the contents of some stateful node, 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 Bergmann Gábor
 */
public abstract class IdentityIndexer extends SpecializedProjectionIndexer {

    protected abstract Collection<Tuple> getTuples();

    /**
     * @param reteContainer
     * @param mask
     */
    public IdentityIndexer(ReteContainer reteContainer, int tupleWidth, Supplier parent, Node activeNode) {
        super(reteContainer, TupleMask.identity(tupleWidth), parent, activeNode);
    }

    public Collection<Tuple> get(Tuple signature) {
        if (contains(signature)) {
            return Collections.singleton(signature);
        } else
            return null;
    }

    /**
     * @param signature
     * @return
     */
    protected boolean contains(Tuple signature) {
        return getTuples().contains(signature);
    }

    public Collection<Tuple> getSignatures() {
        return getTuples();
    }

    public Iterator<Tuple> iterator() {
        return getTuples().iterator();
    }

    public void propagate(Direction direction, Tuple updateElement) {
        propagate(direction, updateElement, updateElement, true);
    }

}