jena-arq/src/main/java/org/apache/jena/sparql/syntax/PatternVarsVisitor.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.jena.sparql.syntax;

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

import org.apache.jena.graph.Triple;
import org.apache.jena.sparql.core.TriplePath;
import org.apache.jena.sparql.core.Var;
import org.apache.jena.sparql.core.VarExprList;
import org.apache.jena.sparql.util.VarUtils;

public class PatternVarsVisitor extends ElementVisitorBase
{
    public Collection<Var> acc;
    public PatternVarsVisitor(Collection<Var> s) {
        acc = s;
    }

    @Override
    public void visit(ElementTriplesBlock el) {
        for ( Iterator<Triple> iter = el.patternElts() ; iter.hasNext() ; ) {
            Triple t = iter.next();
            VarUtils.addVarsFromTriple(acc, t);
        }
    }

    @Override
    public void visit(ElementPathBlock el) {
        for ( Iterator<TriplePath> iter = el.patternElts() ; iter.hasNext() ; ) {
            TriplePath tp = iter.next();
            // If it's triple-izable, then use the triple.
            if ( tp.isTriple() )
                VarUtils.addVarsFromTriple(acc, tp.asTriple());
            else
                VarUtils.addVarsFromTriplePath(acc, tp);
        }
    }

    // Variables here are non-binding.
    @Override public void visit(ElementExists el)       { }
    @Override public void visit(ElementNotExists el)    { }
    @Override public void visit(ElementMinus el)        { }
    @Override public void visit(ElementFilter el)       { }

    @Override
    public void visit(ElementNamedGraph el) {
        VarUtils.addVar(acc, el.getGraphNameNode());
    }

    @Override
    public void visit(ElementSubQuery el) {
        el.getQuery().setResultVars();
        VarExprList x = el.getQuery().getProject();
        acc.addAll(x.getVars());
    }

    @Override
    public void visit(ElementAssign el) {
        acc.add(el.getVar());
    }

    @Override
    public void visit(ElementBind el) {
        acc.add(el.getVar());
    }

    @Override
    public void visit(ElementFind el) {
        acc.add(el.getVar());
        VarUtils.addVarsFromTriple(acc, el.getTriple());
    }

    @Override
    public void visit(ElementData el) {
        acc.addAll(el.getVars());
    }

//    @Override
//    public void visit(ElementService el) {
//        // Although if this isn't defined elsewhere the query won't work.
//        VarUtils.addVar(acc, el.getServiceNode());
//    }
}