org.apache.hadoop.hive.ql.udf.generic.GenericUDFNvl Maven / Gradle / Ivy
/**
* 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.udf.generic;
import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.exec.UDFArgumentLengthException;
import org.apache.hadoop.hive.ql.exec.UDFArgumentTypeException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
@Description(name = "nvl",
value = "_FUNC_(value,default_value) - Returns default value if value is null else returns value",
extended = "Example:\n"
+ " > SELECT _FUNC_(null,'bla') FROM src LIMIT 1;\n" + " bla")
public class GenericUDFNvl extends GenericUDF{
private transient GenericUDFUtils.ReturnObjectInspectorResolver returnOIResolver;
private transient ObjectInspector[] argumentOIs;
@Override
public ObjectInspector initialize(ObjectInspector[] arguments) throws UDFArgumentException {
argumentOIs = arguments;
if (arguments.length != 2) {
throw new UDFArgumentLengthException(
"The operator 'NVL' accepts 2 arguments.");
}
returnOIResolver = new GenericUDFUtils.ReturnObjectInspectorResolver(true);
if (!(returnOIResolver.update(arguments[0]) && returnOIResolver
.update(arguments[1]))) {
throw new UDFArgumentTypeException(2,
"The first and seconds arguments of function NLV should have the same type, "
+ "but they are different: \"" + arguments[0].getTypeName()
+ "\" and \"" + arguments[1].getTypeName() + "\"");
}
return returnOIResolver.get();
}
@Override
public Object evaluate(DeferredObject[] arguments) throws HiveException {
Object retVal = returnOIResolver.convertIfNecessary(arguments[0].get(),
argumentOIs[0]);
if (retVal == null ){
retVal = returnOIResolver.convertIfNecessary(arguments[1].get(),
argumentOIs[1]);
}
return retVal;
}
@Override
public String getDisplayString(String[] children) {
StringBuilder sb = new StringBuilder();
sb.append("if ");
sb.append(children[0]);
sb.append(" is null ");
sb.append("returns");
sb.append(children[1]);
return sb.toString() ;
}
}