/**
* 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 java.util.ArrayList;
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.MapObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector.Category;
/**
* GenericUDFMapKeys.
*
*/
@Description(name = "map_keys", value = "_FUNC_(map) - "
+ "Returns an unordered array containing the keys of the input map.")
public class GenericUDFMapKeys extends GenericUDF {
private MapObjectInspector mapOI;
private final ArrayList<Object> retArray = new ArrayList<Object>();
@Override
public ObjectInspector initialize(ObjectInspector[] arguments)
throws UDFArgumentException {
if (arguments.length != 1) {
throw new UDFArgumentLengthException("The function MAP_KEYS only accepts one argument.");
} else if (!(arguments[0] instanceof MapObjectInspector)) {
throw new UDFArgumentTypeException(0, "\""
+ Category.MAP.toString().toLowerCase()
+ "\" is expected at function MAP_KEYS, " + "but \""
+ arguments[0].getTypeName() + "\" is found");
}
mapOI = (MapObjectInspector) arguments[0];
ObjectInspector mapKeyOI = mapOI.getMapKeyObjectInspector();
return ObjectInspectorFactory.getStandardListObjectInspector(mapKeyOI);
}
@Override
public Object evaluate(DeferredObject[] arguments) throws HiveException {
retArray.clear();
Object mapObj = arguments[0].get();
retArray.addAll(mapOI.getMap(mapObj).keySet());
return retArray;
}
@Override
public String getDisplayString(String[] children) {
assert children.length == 1;
return "map_keys(" + children[0] + ")";
}
}