/*
* 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.List;
import org.apache.pig.data.DataType;
import org.apache.pig.impl.logicalLayer.FrontendException;
import org.apache.pig.impl.plan.PlanValidationException;
import org.apache.pig.newplan.DependencyOrderWalker;
import org.apache.pig.newplan.OperatorPlan;
import org.apache.pig.newplan.logical.expression.DereferenceExpression;
import org.apache.pig.newplan.logical.expression.LogicalExpression;
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.optimizer.AllExpressionVisitor;
import org.apache.pig.newplan.logical.relational.LogicalSchema;
/**
* Logical plan visitor which will convert all column alias references to column
* indexes, using the underlying anonymous expression plan visitor.
*/
public class ColumnAliasConversionVisitor extends AllExpressionVisitor {
public ColumnAliasConversionVisitor(OperatorPlan plan) throws FrontendException {
super( plan, new DependencyOrderWalker( plan ) );
}
@Override
protected LogicalExpressionVisitor getVisitor(LogicalExpressionPlan exprPlan)
throws FrontendException {
return new LogicalExpressionVisitor( exprPlan, new DependencyOrderWalker( exprPlan ) ) {
@Override
public void visit(ProjectExpression expr) throws FrontendException {
expr.setColumnNumberFromAlias();
}
public void visit(DereferenceExpression expr) throws FrontendException {
List<Object> rawCols = expr.getRawColumns();
if( rawCols.isEmpty() ) {
return;
}
List<Integer> cols = new ArrayList<Integer>( rawCols.size() );
LogicalExpressionPlan plan = (LogicalExpressionPlan)expr.getPlan();
LogicalExpression pred = (LogicalExpression)plan.getSuccessors( expr ).get(0);
LogicalSchema schema = null;
if( pred.getFieldSchema().type == DataType.BAG ) {
if( pred.getFieldSchema().schema != null ) {
schema = pred.getFieldSchema().schema.getField(0).schema;
if (schema!=null && schema.size()==1 && schema.getField(0).type==DataType.TUPLE) {
schema = schema.getField(0).schema;
}
}
}
else {
schema = pred.getFieldSchema().schema;
}
int col = -1;
for( Object rc : rawCols ) {
if( rc instanceof Integer ) {
col = (Integer)rc;
if( schema != null && schema.size()!=0 && col >= schema.size() ) {
throw new PlanValidationException( expr, "Out of bound access. Trying to access non-existent column: " +
col + ". Schema " + schema.toString(false) + " has " + schema.size() + " column(s).", 1000 );
}
cols.add( (Integer)rc );
} else {
col = schema == null ? -1 : schema.getFieldPosition( (String)rc );
if( col == -1 ) {
throw new PlanValidationException( expr, "Invalid field reference. Referenced field [" +
rc + "] does not exist in schema: " + (schema!=null?schema.toString(false):"") + "." , 1000);
}
cols.add( col );
}
}
expr.setBagColumns( cols );
}
};
}
}