content: /*
   * 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.asterix.runtime.aggregates.std;
  
  import java.io.IOException;
  
  import org.apache.asterix.formats.nontagged.SerializerDeserializerProvider;
  import org.apache.asterix.om.base.AInt64;
  import org.apache.asterix.om.base.AMutableInt64;
  import org.apache.asterix.om.base.ANull;
  import org.apache.asterix.om.types.ATypeTag;
  import org.apache.asterix.om.types.BuiltinType;
  import org.apache.asterix.om.types.EnumDeserializer;
  import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluator;
  import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluatorFactory;
  import org.apache.hyracks.api.context.IEvaluatorContext;
  import org.apache.hyracks.api.dataflow.value.ISerializerDeserializer;
  import org.apache.hyracks.api.exceptions.HyracksDataException;
  import org.apache.hyracks.api.exceptions.SourceLocation;
  import org.apache.hyracks.data.std.api.IPointable;
  import org.apache.hyracks.data.std.primitive.VoidPointable;
  import org.apache.hyracks.data.std.util.ArrayBackedValueStorage;
  import org.apache.hyracks.dataflow.common.data.accessors.IFrameTupleReference;
  
  /**
   * COUNT returns the number of items in the given list. Note that COUNT(NULL) is not allowed.
   */
  public abstract class AbstractCountAggregateFunction extends AbstractAggregateFunction {
      private AMutableInt64 result = new AMutableInt64(-1);
      @SuppressWarnings("unchecked")
      private ISerializerDeserializer<AInt64> int64Serde =
              SerializerDeserializerProvider.INSTANCE.getSerializerDeserializer(BuiltinType.AINT64);
      @SuppressWarnings("unchecked")
      private ISerializerDeserializer<ANull> nullSerde =
              SerializerDeserializerProvider.INSTANCE.getSerializerDeserializer(BuiltinType.ANULL);
      private IPointable inputVal = new VoidPointable();
      private IScalarEvaluator eval;
      protected long cnt;
      protected boolean nullRes;
  
      private ArrayBackedValueStorage resultStorage = new ArrayBackedValueStorage();
  
      public AbstractCountAggregateFunction(IScalarEvaluatorFactory[] args, IEvaluatorContext context,
              SourceLocation sourceLoc) throws HyracksDataException {
          super(sourceLoc);
          eval = args[0].createScalarEvaluator(context);
      }
  
      @Override
      public void init() throws HyracksDataException {
          cnt = 0;
          nullRes = false;
      }
  
      @Override
      public void step(IFrameTupleReference tuple) throws HyracksDataException {
          eval.evaluate(tuple, inputVal);
          ATypeTag typeTag =
                  EnumDeserializer.ATYPETAGDESERIALIZER.deserialize(inputVal.getByteArray()[inputVal.getStartOffset()]);
          // Ignore SYSTEM_NULL.
          if (typeTag == ATypeTag.NULL || typeTag == ATypeTag.MISSING) {
              processNull();
          } else if (typeTag != ATypeTag.SYSTEM_NULL) {
              processValue(typeTag);
          }
      }
  
      @Override
      public void finish(IPointable resultPointable) throws HyracksDataException {
          resultStorage.reset();
          try {
              if (nullRes) {
                  nullSerde.serialize(ANull.NULL, resultStorage.getDataOutput());
              } else {
                  result.setValue(cnt);
                  int64Serde.serialize(result, resultStorage.getDataOutput());
              }
          } catch (IOException e) {
              throw HyracksDataException.create(e);
          }
          resultPointable.set(resultStorage);
      }
  
      @Override
      public void finishPartial(IPointable resultPointable) throws HyracksDataException {
          finish(resultPointable);
      }
  
      protected abstract void processNull();
  
      protected void processValue(ATypeTag tag) {
          cnt++;
      }
  }
  