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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.exec;

import java.util.ArrayList;
import java.util.List;

import org.apache.hadoop.hive.serde2.typeinfo.TypeInfo;
import org.apache.hadoop.hive.serde2.typeinfo.TypeInfoFactory;

/**
 * Resolver for Numeric UDAFs like sum and avg. If the input argument is string
 * or date, the resolver returns the evaluator whose iterate function operates
 * on doubles.
 */
public class NumericUDAFEvaluatorResolver extends DefaultUDAFEvaluatorResolver {

  /**
   * Constructor.
   */
  public NumericUDAFEvaluatorResolver(Class udafClass) {
    super(udafClass);
  }

  /*
   * (non-Javadoc)
   * 
   * @see
   * org.apache.hadoop.hive.ql.exec.UDAFMethodResolver#getEvaluatorClass(java
   * .util.List)
   */
  @Override
  public Class getEvaluatorClass(
      List argTypeInfos) throws UDFArgumentException {
    // Go through the argClasses and for any string, void or date time, start
    // looking for doubles
    ArrayList args = new ArrayList();
    for (TypeInfo arg : argTypeInfos) {
      if (arg.equals(TypeInfoFactory.voidTypeInfo)
          || arg.equals(TypeInfoFactory.stringTypeInfo)) {
        args.add(TypeInfoFactory.doubleTypeInfo);
      } else {
        args.add(arg);
      }
    }

    return super.getEvaluatorClass(args);
  }
}