/*
* 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.twilmes.sql.gremlin.processor;
import org.apache.calcite.rel.RelNode;
/**
* Does a post-order depth-first traversal of the Calcite operator tree.
*/
public class RelWalker {
private final RelVisitor visitor;
public RelWalker(RelNode root, RelVisitor visitor) {
this.visitor = visitor;
walk(root);
}
private void walk(RelNode node) {
if (node == null) return;
for (RelNode child : node.getInputs()) {
walk(child);
}
visitor.visit(node);
}
}
