/*
 * 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.algebra.walker;

import org.apache.jena.sparql.algebra.OpVisitor ;
import org.apache.jena.sparql.algebra.op.OpMinus ;
import org.apache.jena.sparql.algebra.op.OpProject ;
import org.apache.jena.sparql.expr.ExprFunctionOp ;
import org.apache.jena.sparql.expr.ExprVisitor ;

/** Walk algebra 
 * Do project, don't walk into it.
 * Don't walk into RHS of MINUS nor ExprFunctionOp (NOT EXISTS etc)
 */
public class WalkerVisitorVisible extends WalkerVisitor {
    
    public WalkerVisitorVisible(OpVisitor opVisitor, ExprVisitor exprVisitor, OpVisitor before, OpVisitor after) {
        super(opVisitor, exprVisitor, before, after) ;
    }

    @Override
    public void visit(OpProject op) {
        before(op) ;
        if ( opVisitor != null )
            op.visit(opVisitor);
        // Skip inner.
        after(op) ;
    }

    @Override
    public void visit(OpMinus op) {
        before(op) ;
        if (op.getLeft() != null)
            op.getLeft().visit(this) ;
        // Skip right.
        // if ( op.getRight() != null ) op.getRight().visit(this) ;
        if (opVisitor != null)
            op.visit(opVisitor) ;
        after(op) ;
    }
    
    @Override
    public void visit(ExprFunctionOp funcOp) {
        // Skip the pattern
        //walk(funcOp.getGraphPattern());
        if ( exprVisitor != null )
            funcOp.visit(exprVisitor) ;
    }
    

}


