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.dataflow.data.nontagged.serde.ABooleanSerializerDeserializer;
  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.types.ATypeTag;
  import org.apache.asterix.om.types.BuiltinType;
  import org.apache.asterix.om.types.hierachy.ATypeHierarchy;
  import org.apache.asterix.runtime.exceptions.TypeMismatchException;
  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.UTF8StringPointable;
  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;
  
  public class EditDistanceStringIsFilterableEvaluator implements IScalarEvaluator {
  
      protected final ArrayBackedValueStorage resultStorage = new ArrayBackedValueStorage();
      protected final DataOutput output = resultStorage.getDataOutput();
      protected final IPointable stringPtr = new VoidPointable();
      protected final IPointable edThreshPtr = new VoidPointable();
      protected final IPointable gramLenPtr = new VoidPointable();
      protected final IPointable usePrePostPtr = new VoidPointable();
  
      protected final IScalarEvaluator stringEval;
      protected final IScalarEvaluator edThreshEval;
      protected final IScalarEvaluator gramLenEval;
      protected final IScalarEvaluator usePrePostEval;
  
      @SuppressWarnings("unchecked")
      private final ISerializerDeserializer<ABoolean> booleanSerde =
              SerializerDeserializerProvider.INSTANCE.getSerializerDeserializer(BuiltinType.ABOOLEAN);
  
      private final UTF8StringPointable utf8Ptr = new UTF8StringPointable();
  
      public EditDistanceStringIsFilterableEvaluator(IScalarEvaluatorFactory[] args, IEvaluatorContext context)
              throws HyracksDataException {
          stringEval = args[0].createScalarEvaluator(context);
          edThreshEval = args[1].createScalarEvaluator(context);
          gramLenEval = args[2].createScalarEvaluator(context);
          usePrePostEval = args[3].createScalarEvaluator(context);
      }
  
      @Override
      public void evaluate(IFrameTupleReference tuple, IPointable result) throws HyracksDataException {
          resultStorage.reset();
  
          stringEval.evaluate(tuple, stringPtr);
          edThreshEval.evaluate(tuple, edThreshPtr);
          gramLenEval.evaluate(tuple, gramLenPtr);
          usePrePostEval.evaluate(tuple, usePrePostPtr);
  
          if (PointableHelper.checkAndSetMissingOrNull(result, stringPtr, edThreshPtr, gramLenPtr, usePrePostPtr)) {
              return;
          }
  
          // Check type and compute string length.
          byte typeTag = stringPtr.getByteArray()[stringPtr.getStartOffset()];
          if (typeTag != ATypeTag.SERIALIZED_STRING_TYPE_TAG) {
              throw new TypeMismatchException(BuiltinFunctions.EDIT_DISTANCE_STRING_IS_FILTERABLE, 0, typeTag,
                      ATypeTag.SERIALIZED_STRING_TYPE_TAG);
          }
          utf8Ptr.set(stringPtr.getByteArray(), stringPtr.getStartOffset() + 1, stringPtr.getLength());
          int strLen = utf8Ptr.getStringLength();
  
          // Check type and extract edit-distance threshold.
          long edThresh = ATypeHierarchy.getIntegerValue(BuiltinFunctions.EDIT_DISTANCE_LIST_IS_FILTERABLE.getName(), 1,
                  edThreshPtr.getByteArray(), edThreshPtr.getStartOffset());
  
          // Check type and extract gram length.
          long gramLen = ATypeHierarchy.getIntegerValue(BuiltinFunctions.EDIT_DISTANCE_LIST_IS_FILTERABLE.getName(), 2,
                  gramLenPtr.getByteArray(), gramLenPtr.getStartOffset());
  
          // Check type and extract usePrePost flag.
          typeTag = usePrePostPtr.getByteArray()[usePrePostPtr.getStartOffset()];
          if (typeTag != ATypeTag.SERIALIZED_BOOLEAN_TYPE_TAG) {
              throw new TypeMismatchException(BuiltinFunctions.EDIT_DISTANCE_STRING_IS_FILTERABLE, 3, typeTag,
                      ATypeTag.SERIALIZED_BOOLEAN_TYPE_TAG);
          }
          boolean usePrePost = ABooleanSerializerDeserializer.getBoolean(usePrePostPtr.getByteArray(),
                  usePrePostPtr.getStartOffset() + 1);
  
          // Compute result.
          long numGrams = usePrePost ? strLen + gramLen - 1 : strLen - gramLen + 1;
          long lowerBound = numGrams - edThresh * gramLen;
          try {
              if (lowerBound <= 0 || strLen == 0) {
                  booleanSerde.serialize(ABoolean.FALSE, output);
              } else {
                  booleanSerde.serialize(ABoolean.TRUE, output);
              }
          } catch (IOException e) {
              throw HyracksDataException.create(e);
          }
          result.set(resultStorage);
      }
  }
  