/*
* 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.pig.newplan.logical.visitor;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.apache.pig.impl.logicalLayer.FrontendException;
import org.apache.pig.newplan.DependencyOrderWalker;
import org.apache.pig.newplan.Operator;
import org.apache.pig.newplan.OperatorPlan;
import org.apache.pig.newplan.logical.relational.LOForEach;
import org.apache.pig.newplan.logical.relational.LOGenerate;
import org.apache.pig.newplan.logical.relational.LogicalPlan;
import org.apache.pig.newplan.logical.relational.LogicalRelationalNodesVisitor;
public class DanglingNestedNodeRemover extends LogicalRelationalNodesVisitor {
public DanglingNestedNodeRemover(OperatorPlan plan)
throws FrontendException {
super(plan, new DependencyOrderWalker(plan));
}
@Override
public void visit(LOForEach foreach) throws FrontendException {
LogicalPlan innerPlan = foreach.getInnerPlan();
List<Operator> opsToRemove = new ArrayList<Operator>();
Iterator<Operator> ops = innerPlan.getOperators();
while (ops.hasNext()) {
Operator op = ops.next();
// Check if op leads to LOGenerate, otherwise, candidate to remove
Operator currentOp = op;
boolean endWithNoLOGenerate = false;
while (!(currentOp instanceof LOGenerate)) {
if (innerPlan.getSuccessors(currentOp)==null) {
endWithNoLOGenerate = true;
break;
}
currentOp = innerPlan.getSuccessors(currentOp).get(0);
}
if (endWithNoLOGenerate)
opsToRemove.add(op);
}
for (Operator op : opsToRemove) {
innerPlan.removeAndReconnect(op);
}
}
}