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.evaluators.functions;
  
  import java.io.DataOutput;
  import java.io.IOException;
  
  import org.apache.asterix.common.annotations.MissingNullInOutFunction;
  import org.apache.asterix.dataflow.data.nontagged.serde.AOrderedListSerializerDeserializer;
  import org.apache.asterix.dataflow.data.nontagged.serde.AUnorderedListSerializerDeserializer;
  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.ATypeTag;
  import org.apache.asterix.om.types.BuiltinType;
  import org.apache.asterix.om.types.EnumDeserializer;
  import org.apache.asterix.om.types.hierachy.ATypeHierarchy;
  import org.apache.asterix.runtime.evaluators.base.AbstractScalarFunctionDynamicDescriptor;
  import org.apache.asterix.runtime.exceptions.TypeMismatchException;
  import org.apache.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
  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.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;
  
  /**
   * Checks whether a list with an edit distance threshold can be filtered with a lower bounding on the number
   * of common list elements. This function returns 'true' if the lower bound on the number of common elements
   * is positive, 'false' otherwise. For example, this function is used during an indexed nested-loop join based
   * on edit distance. We partition the tuples of the probing dataset into those that are filterable and those
   * that are not. Those that are filterable are forwarded to the index. The others are are fed into a (non
   * indexed) nested-loop join.
   */
  
  @MissingNullInOutFunction
  public class EditDistanceListIsFilterableDescriptor extends AbstractScalarFunctionDynamicDescriptor {
  
      private static final long serialVersionUID = 1L;
  
      public static final IFunctionDescriptorFactory FACTORY = EditDistanceListIsFilterableDescriptor::new;
  
      @Override
      public IScalarEvaluatorFactory createEvaluatorFactory(final IScalarEvaluatorFactory[] args) {
          return new IScalarEvaluatorFactory() {
              private static final long serialVersionUID = 1L;
  
              @Override
              public IScalarEvaluator createScalarEvaluator(IEvaluatorContext ctx) throws HyracksDataException {
                  return new EditDistanceListIsFilterableEvaluator(args, ctx);
              }
          };
      }
  
      @Override
      public FunctionIdentifier getIdentifier() {
          return BuiltinFunctions.EDIT_DISTANCE_LIST_IS_FILTERABLE;
      }
  
      private static class EditDistanceListIsFilterableEvaluator implements IScalarEvaluator {
  
          protected final IPointable listPtr = new VoidPointable();
          protected final IPointable edThreshPtr = new VoidPointable();
          protected final ArrayBackedValueStorage resultStorage = new ArrayBackedValueStorage();
          protected final DataOutput output = resultStorage.getDataOutput();
  
          protected final IScalarEvaluator listEval;
          protected final IScalarEvaluator edThreshEval;
  
          @SuppressWarnings("unchecked")
          private final ISerializerDeserializer<ABoolean> booleanSerde =
                  SerializerDeserializerProvider.INSTANCE.getSerializerDeserializer(BuiltinType.ABOOLEAN);
  
          public EditDistanceListIsFilterableEvaluator(IScalarEvaluatorFactory[] args, IEvaluatorContext context)
                  throws HyracksDataException {
              listEval = args[0].createScalarEvaluator(context);
              edThreshEval = args[1].createScalarEvaluator(context);
          }
  
          @Override
          public void evaluate(IFrameTupleReference tuple, IPointable result) throws HyracksDataException {
              resultStorage.reset();
  
              listEval.evaluate(tuple, listPtr);
              edThreshEval.evaluate(tuple, edThreshPtr);
  
              if (PointableHelper.checkAndSetMissingOrNull(result, listPtr, edThreshPtr)) {
                  return;
              }
  
              // Check type and compute string length.
              byte[] bytes = listPtr.getByteArray();
              int offset = listPtr.getStartOffset();
  
              ATypeTag typeTag = EnumDeserializer.ATYPETAGDESERIALIZER.deserialize(bytes[offset]);
              long listLen;
              switch (typeTag) {
                  case MULTISET:
                      listLen = AUnorderedListSerializerDeserializer.getNumberOfItems(bytes, offset);
                      break;
                  case ARRAY:
                      listLen = AOrderedListSerializerDeserializer.getNumberOfItems(bytes, offset);
                      break;
                  default:
                      throw new TypeMismatchException(BuiltinFunctions.EDIT_DISTANCE_LIST_IS_FILTERABLE, 0,
                              ATypeTag.SERIALIZED_UNORDEREDLIST_TYPE_TAG, ATypeTag.SERIALIZED_ORDEREDLIST_TYPE_TAG);
              }
  
              // Check type and extract edit-distance threshold.
              bytes = edThreshPtr.getByteArray();
              offset = edThreshPtr.getStartOffset();
              long edThresh = ATypeHierarchy.getIntegerValue(BuiltinFunctions.EDIT_DISTANCE_LIST_IS_FILTERABLE.getName(),
                      1, bytes, offset);
  
              // Compute result.
              long lowerBound = listLen - edThresh;
              try {
                  if (lowerBound <= 0) {
                      booleanSerde.serialize(ABoolean.FALSE, output);
                  } else {
                      booleanSerde.serialize(ABoolean.TRUE, output);
                  }
              } catch (IOException e) {
                  throw HyracksDataException.create(e);
              }
              result.set(resultStorage);
          }
      }
  }
  