TripleRefCollector.java
/*******************************************************************************
* Copyright (c) 2020 Eclipse RDF4J contributors.
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Distribution License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*******************************************************************************/
package org.eclipse.rdf4j.query.parser.sparql;
import java.util.HashMap;
import java.util.Map;
import org.eclipse.rdf4j.query.algebra.Filter;
import org.eclipse.rdf4j.query.algebra.QueryModelNode;
import org.eclipse.rdf4j.query.algebra.TripleRef;
import org.eclipse.rdf4j.query.algebra.ValueExprTripleRef;
import org.eclipse.rdf4j.query.algebra.helpers.AbstractQueryModelVisitor;
// constructs a map from variable name to TripleRef or ValueExprTripleRef for processing extensions
public class TripleRefCollector extends AbstractQueryModelVisitor<RuntimeException> {
public static Map<String, Object> process(QueryModelNode node) {
TripleRefCollector collector = new TripleRefCollector();
node.visit(collector);
return collector.getTripleRefs();
}
private final Map<String, Object> tripleRefs = new HashMap<>();
public Map<String, Object> getTripleRefs() {
return tripleRefs;
}
@Override
public void meet(Filter node) {
// Skip boolean constraints
node.getArg().visit(this);
}
@Override
public void meet(TripleRef node) {
tripleRefs.put(node.getExprVar().getName(), node);
}
@Override
public void meet(ValueExprTripleRef node) {
tripleRefs.put(node.getExtVarName(), node);
}
@Override
public void meetOther(QueryModelNode node) {
if (node instanceof TripleRef) {
tripleRefs.put(((TripleRef) node).getExprVar().getName(), node);
} else if (node instanceof ValueExprTripleRef) {
tripleRefs.put(((ValueExprTripleRef) node).getExtVarName(), node);
} else {
super.meetOther(node);
}
}
}