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.stream;
  
  import org.apache.asterix.formats.nontagged.SerializerDeserializerProvider;
  import org.apache.asterix.om.base.ABoolean;
  import org.apache.asterix.om.functions.BuiltinFunctions;
  import org.apache.asterix.om.functions.IFunctionDescriptorFactory;
  import org.apache.asterix.om.types.BuiltinType;
  import org.apache.asterix.runtime.aggregates.base.AbstractAggregateFunctionDynamicDescriptor;
  import org.apache.asterix.runtime.aggregates.std.AbstractAggregateFunction;
  import org.apache.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
  import org.apache.hyracks.algebricks.runtime.base.IAggregateEvaluator;
  import org.apache.hyracks.algebricks.runtime.base.IAggregateEvaluatorFactory;
  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.data.std.api.IPointable;
  import org.apache.hyracks.data.std.util.ArrayBackedValueStorage;
  import org.apache.hyracks.dataflow.common.data.accessors.IFrameTupleReference;
  
  public class EmptyStreamAggregateDescriptor extends AbstractAggregateFunctionDynamicDescriptor {
  
      private static final long serialVersionUID = 1L;
  
      public final static FunctionIdentifier FID = BuiltinFunctions.EMPTY_STREAM;
      public static final IFunctionDescriptorFactory FACTORY = EmptyStreamAggregateDescriptor::new;
  
      @Override
      public IAggregateEvaluatorFactory createAggregateEvaluatorFactory(IScalarEvaluatorFactory[] args) {
          return new IAggregateEvaluatorFactory() {
  
              private static final long serialVersionUID = 1L;
  
              @Override
              public IAggregateEvaluator createAggregateEvaluator(final IEvaluatorContext ctx)
                      throws HyracksDataException {
  
                  return new AbstractAggregateFunction(sourceLoc) {
  
                      private ArrayBackedValueStorage resultStorage = new ArrayBackedValueStorage();
                      @SuppressWarnings("rawtypes")
                      private ISerializerDeserializer serde =
                              SerializerDeserializerProvider.INSTANCE.getSerializerDeserializer(BuiltinType.ABOOLEAN);
  
                      boolean res = true;
  
                      @Override
                      public void init() throws HyracksDataException {
                          res = true;
                      }
  
                      @Override
                      public void step(IFrameTupleReference tuple) throws HyracksDataException {
                          res = false;
                      }
  
                      @SuppressWarnings("unchecked")
                      @Override
                      public void finish(IPointable result) throws HyracksDataException {
                          resultStorage.reset();
                          ABoolean b = res ? ABoolean.TRUE : ABoolean.FALSE;
                          serde.serialize(b, resultStorage.getDataOutput());
                          result.set(resultStorage);
                      }
  
                      @Override
                      public void finishPartial(IPointable result) throws HyracksDataException {
                          finish(result);
                      }
                  };
              }
          };
      }
  
      @Override
      public FunctionIdentifier getIdentifier() {
          return FID;
      }
  
  }
  