GenericUDFArray.java example

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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.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.UDFArgumentTypeException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorConverters;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorConverters.Converter;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.VoidObjectInspector;

/**
 * GenericUDFArray.
 *
 */
@Description(name = "array",
    value = "_FUNC_(n0, n1...) - Creates an array with the given elements ")
public class GenericUDFArray extends GenericUDF {
  private transient Converter[] converters;
  private transient ArrayList<Object> ret = new ArrayList<Object>();

  @Override
  public ObjectInspector initialize(ObjectInspector[] arguments) throws UDFArgumentException {

    GenericUDFUtils.ReturnObjectInspectorResolver returnOIResolver = new GenericUDFUtils.ReturnObjectInspectorResolver(true);

    for (int i = 0; i < arguments.length; i++) {
      if (!returnOIResolver.update(arguments[i])) {
        throw new UDFArgumentTypeException(i, "Argument type \""
            + arguments[i].getTypeName()
            + "\" is different from preceding arguments. "
            + "Previous type was \"" + arguments[i - 1].getTypeName() + "\"");
      }
    }

    converters = new Converter[arguments.length];

    ObjectInspector returnOI =
        returnOIResolver.get(PrimitiveObjectInspectorFactory.javaStringObjectInspector);
    for (int i = 0; i < arguments.length; i++) {
      converters[i] = ObjectInspectorConverters.getConverter(arguments[i],
          returnOI);
    }

    return ObjectInspectorFactory.getStandardListObjectInspector(returnOI);
  }

  @Override
  public Object evaluate(DeferredObject[] arguments) throws HiveException {
    ret.clear();
    for (int i = 0; i < arguments.length; i++) {
      ret.add(converters[i].convert(arguments[i].get()));
    }
    return ret;

  }

  @Override
  public String getDisplayString(String[] children) {
    return getStandardDisplayString("array", children, ",");
  }
}