/**
* 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.hadoop.hive.ql.exec;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
/**
* Increases version number of each evaluations for correct caching
*/
public class ExprNodeEvaluatorHead extends ExprNodeEvaluator {
private int counter;
private final ExprNodeEvaluator referencing;
public ExprNodeEvaluatorHead(ExprNodeEvaluator referencing) {
super(referencing.getExpr(), referencing.getConf());
this.referencing = referencing;
}
@Override
public ObjectInspector initialize(ObjectInspector rowInspector) throws HiveException {
return outputOI = referencing.initialize(rowInspector);
}
@Override
protected Object _evaluate(Object row, int version) throws HiveException {
return referencing.evaluate(row, next());
}
private int next() {
return ++counter < 0 ? counter = 0 : counter;
}
}