/**
* 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 static org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorUtils.PrimitiveGrouping.NUMERIC_GROUP;
import static org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorUtils.PrimitiveGrouping.VOID_GROUP;
import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorConverters.Converter;
import org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector.PrimitiveCategory;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.io.LongWritable;
/**
* GenericUDFFactorial
*
*/
@Description(
name = "factorial",
value = "_FUNC_(int) - Returns n factorial. Valid n is [0..20].",
extended = "Returns null if n is out of [0..20] range.\n"
+ "Example:\n > SELECT _FUNC_(5);\n 120")
public class GenericUDFFactorial extends GenericUDF {
/** All long-representable factorials */
static final long[] FACTORIALS = new long[] {
1l, 1l, 2l,
6l, 24l, 120l,
720l, 5040l, 40320l,
362880l, 3628800l, 39916800l,
479001600l, 6227020800l, 87178291200l,
1307674368000l, 20922789888000l, 355687428096000l,
6402373705728000l, 121645100408832000l, 2432902008176640000l };
private transient PrimitiveCategory[] inputTypes = new PrimitiveCategory[1];
private transient Converter[] converters = new Converter[1];
private final LongWritable output = new LongWritable();
@Override
public ObjectInspector initialize(ObjectInspector[] arguments) throws UDFArgumentException {
checkArgsSize(arguments, 1, 1);
checkArgPrimitive(arguments, 0);
checkArgGroups(arguments, 0, inputTypes, NUMERIC_GROUP, VOID_GROUP);
obtainIntConverter(arguments, 0, inputTypes, converters);
ObjectInspector outputOI = PrimitiveObjectInspectorFactory.writableLongObjectInspector;
return outputOI;
}
@Override
public Object evaluate(DeferredObject[] arguments) throws HiveException {
Integer val = getIntValue(arguments, 0, converters);
if (val == null || val < 0 || val > 20) {
return null;
}
long factorial = FACTORIALS[val];
output.set(factorial);
return output;
}
@Override
public String getDisplayString(String[] children) {
return getStandardDisplayString(getFuncName(), children);
}
@Override
protected String getFuncName() {
return "factorial";
}
}