/*
* 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.optimizer;
import java.util.List;
import org.apache.pig.impl.logicalLayer.FrontendException;
import org.apache.pig.newplan.DependencyOrderWalker;
import org.apache.pig.newplan.DepthFirstWalker;
import org.apache.pig.newplan.OperatorPlan;
import org.apache.pig.newplan.logical.expression.LogicalExpressionPlan;
import org.apache.pig.newplan.logical.expression.LogicalExpressionVisitor;
import org.apache.pig.newplan.logical.expression.ProjectExpression;
import org.apache.pig.newplan.logical.relational.LOGenerate;
import org.apache.pig.newplan.logical.relational.LogicalRelationalOperator;
import org.apache.pig.newplan.logical.relational.LogicalSchema;
import org.apache.pig.newplan.optimizer.PlanTransformListener;
/**
* A PlanTransformListener that will patch up references in projections.
*
*/
public class ProjectionPatcher implements PlanTransformListener {
/**
* @link org.apache.pig.newplan.optimizer.PlanTransformListener#transformed(org.apache.pig.newplan.OperatorPlan, org.apache.pig.newplan.OperatorPlan)
*/
@Override
public void transformed(OperatorPlan fp, OperatorPlan tp)
throws FrontendException {
ProjectionFinder pf = new ProjectionFinder(tp);
pf.visit();
}
private static class ProjectionRewriter extends LogicalExpressionVisitor {
ProjectionRewriter(OperatorPlan p, LogicalRelationalOperator cop) throws FrontendException {
super(p, new DepthFirstWalker(p));
}
@Override
public void visit(ProjectExpression p) throws FrontendException {
// if project is a project-star or range, ie it could not be expanded
// then its not possible to determine the matching input columns
// before runtime
if (p.isRangeOrStarProject()) {
return;
}
// Get the uid for this projection. It must match the uid of the
// value it is projecting.
long myUid = p.getFieldSchema().uid;
// Find the operator this projection references
LogicalRelationalOperator pred = p.findReferent();
if (p.getAttachedRelationalOp() instanceof LOGenerate && p.getPlan().getSuccessors(p)==null) {
// No need to adjust
return;
}
else {
// Get the schema for this operator and search it for the matching uid
int match = -1;
LogicalSchema schema = pred.getSchema();
if (schema==null)
return;
List<LogicalSchema.LogicalFieldSchema> fields = schema.getFields();
for (int i = 0; i < fields.size(); i++) {
if (fields.get(i).uid == myUid) {
match = i;
break;
}
}
if (match == -1) {
throw new FrontendException("Couldn't find matching uid " + match + " for project "+p, 2229);
}
p.setColNum(match);
}
}
}
public static class ProjectionFinder extends AllExpressionVisitor {
public ProjectionFinder(OperatorPlan plan) throws FrontendException {
super(plan, new DependencyOrderWalker(plan));
}
@Override
protected LogicalExpressionVisitor getVisitor(LogicalExpressionPlan expr) throws FrontendException {
return new ProjectionRewriter(expr, currentOp);
}
}
}