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/**
 * 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;

import org.apache.hadoop.hive.common.type.HiveDecimal;
import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDF;
import org.apache.hadoop.hive.serde2.io.DoubleWritable;
import org.apache.hadoop.hive.serde2.io.HiveDecimalWritable;

/**
 * UDFOPDivide.
 *
 */
@Description(name = "/", value = "a _FUNC_ b - Divide a by b", extended = "Example:\n"
    + "  > SELECT 3 _FUNC_ 2 FROM src LIMIT 1;\n" + "  1.5")
/**
 * Note that in SQL, the return type of divide is not necessarily the same
 * as the parameters. For example, 3 / 2 = 1.5, not 1. To follow SQL, we always
 * return a double for divide.
 */
public class UDFOPDivide extends UDF {

  private final DoubleWritable doubleWritable = new DoubleWritable();
  private final HiveDecimalWritable decimalWritable = new HiveDecimalWritable();

  public DoubleWritable evaluate(DoubleWritable a, DoubleWritable b) {
    // LOG.info("Get input " + a.getClass() + ":" + a + " " + b.getClass() + ":"
    // + b);
    if ((a == null) || (b == null)) {
      return null;
    }

    doubleWritable.set(a.get() / b.get());
    return doubleWritable;
  }

  public HiveDecimalWritable evaluate(HiveDecimalWritable a, HiveDecimalWritable b) {
    if ((a == null) || (b == null)) {
      return null;
    }
    if (b.getHiveDecimal().compareTo(HiveDecimal.ZERO) == 0) {
      return null;
    } else {
        decimalWritable.set(a.getHiveDecimal().divide(
          b.getHiveDecimal()));
    }

    return decimalWritable;
  }
}