parquet-hive/parquet-hive-storage-handler/src/main/java/org/apache/hadoop/hive/ql/io/parquet/serde/StandardParquetHiveMapInspector.java

/* 
 * 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.io.parquet.serde;

import java.util.Map;

import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.io.ArrayWritable;
import org.apache.hadoop.io.Writable;

/**
 * The StandardParquetHiveMapInspector will inspect an ArrayWritable, considering it as a Hive map.
 * <p>
 * It can also inspect a Map if Hive decides to inspect the result of an inspection.
 */
public class StandardParquetHiveMapInspector extends AbstractParquetMapInspector {

  public StandardParquetHiveMapInspector(final ObjectInspector keyInspector,
      final ObjectInspector valueInspector) {
    super(keyInspector, valueInspector);
  }

  @Override
  public Object getMapValueElement(final Object data, final Object key) {
    if (data == null || key == null) {
      return null;
    }
    if (data instanceof ArrayWritable) {
      final Writable[] mapContainer = ((ArrayWritable) data).get();

      if (mapContainer == null || mapContainer.length == 0) {
        return null;
      }
      final Writable[] mapArray = ((ArrayWritable) mapContainer[0]).get();
      for (final Writable obj : mapArray) {
        final ArrayWritable mapObj = (ArrayWritable) obj;
        final Writable[] arr = mapObj.get();
        if (key.equals(arr[0])) {
          return arr[1];
        }
      }
      return null;
    }
    if (data instanceof Map) {
      return ((Map) data).get(key);
    }
    throw new UnsupportedOperationException("Cannot inspect " + data.getClass().getCanonicalName());
  }
}