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/tags/release-0.1-rc2/hive/external/ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDFOPNull.java

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Java | 59 lines | 31 code | 7 blank | 21 comment | 4 complexity | c83f93d198146896fb9738a389d8615b MD5 | raw file
 1/**
 2 * Licensed to the Apache Software Foundation (ASF) under one
 3 * or more contributor license agreements.  See the NOTICE file
 4 * distributed with this work for additional information
 5 * regarding copyright ownership.  The ASF licenses this file
 6 * to you under the Apache License, Version 2.0 (the
 7 * "License"); you may not use this file except in compliance
 8 * with the License.  You may obtain a copy of the License at
 9 *
10 *     http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18
19package org.apache.hadoop.hive.ql.udf.generic;
20
21import org.apache.hadoop.hive.ql.exec.Description;
22import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
23import org.apache.hadoop.hive.ql.exec.UDFArgumentLengthException;
24import org.apache.hadoop.hive.ql.metadata.HiveException;
25import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
26import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
27import org.apache.hadoop.io.BooleanWritable;
28
29/**
30 * GenericUDFOPNull.
31 *
32 */
33@Description(name = "isnull", value = "_FUNC_ a - Returns true if a is NULL and false otherwise")
34public class GenericUDFOPNull extends GenericUDF {
35  private BooleanWritable result = new BooleanWritable();
36
37  @Override
38  public ObjectInspector initialize(ObjectInspector[] arguments)
39      throws UDFArgumentException {
40    if (arguments.length != 1) {
41      throw new UDFArgumentLengthException(
42          "The operator 'IS NULL' only accepts 1 argument.");
43    }
44    return PrimitiveObjectInspectorFactory.writableBooleanObjectInspector;
45  }
46
47  @Override
48  public Object evaluate(DeferredObject[] arguments) throws HiveException {
49    result.set(arguments[0].get() == null);
50    return result;
51  }
52
53  @Override
54  public String getDisplayString(String[] children) {
55    assert (children.length == 1);
56    return children[0] + " is null";
57  }
58
59}