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.AOrderedListSerializerDeserializer;
  import org.apache.asterix.dataflow.data.nontagged.serde.AUnorderedListSerializerDeserializer;
  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.EnumDeserializer;
  import org.apache.asterix.om.types.hierachy.ATypeHierarchy;
  import org.apache.asterix.om.utils.NonTaggedFormatUtil;
  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.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;
  
  public class GetItemDescriptor extends AbstractScalarFunctionDynamicDescriptor {
  
      private static final long serialVersionUID = 1L;
  
      public static final IFunctionDescriptorFactory FACTORY = GetItemDescriptor::new;
  
      @Override
      public IScalarEvaluatorFactory createEvaluatorFactory(final IScalarEvaluatorFactory[] args) {
          return new GetItemEvalFactory(args);
      }
  
      @Override
      public FunctionIdentifier getIdentifier() {
          return BuiltinFunctions.GET_ITEM;
      }
  
      private class GetItemEvalFactory implements IScalarEvaluatorFactory {
  
          private static final long serialVersionUID = 1L;
          private IScalarEvaluatorFactory listEvalFactory;
          private IScalarEvaluatorFactory indexEvalFactory;
  
          public GetItemEvalFactory(IScalarEvaluatorFactory[] args) {
              this.listEvalFactory = args[0];
              this.indexEvalFactory = args[1];
          }
  
          @Override
          public IScalarEvaluator createScalarEvaluator(final IEvaluatorContext ctx) throws HyracksDataException {
              return new IScalarEvaluator() {
  
                  private final ArrayBackedValueStorage resultStorage = new ArrayBackedValueStorage();
                  private final DataOutput output = resultStorage.getDataOutput();
                  private IPointable inputArgList = new VoidPointable();
                  private IPointable inputArgIdx = new VoidPointable();
                  private IScalarEvaluator evalList = listEvalFactory.createScalarEvaluator(ctx);
                  private IScalarEvaluator evalIdx = indexEvalFactory.createScalarEvaluator(ctx);
                  private byte[] missingBytes = new byte[] { ATypeTag.SERIALIZED_MISSING_TYPE_TAG };
  
                  @Override
                  public void evaluate(IFrameTupleReference tuple, IPointable result) throws HyracksDataException {
                      try {
                          evalList.evaluate(tuple, inputArgList);
                          evalIdx.evaluate(tuple, inputArgIdx);
  
                          if (PointableHelper.checkAndSetMissingOrNull(result, inputArgList, inputArgIdx)) {
                              return;
                          }
  
                          byte[] serList = inputArgList.getByteArray();
                          int offset = inputArgList.getStartOffset();
                          byte[] indexBytes = inputArgIdx.getByteArray();
                          int indexOffset = inputArgIdx.getStartOffset();
  
                          int itemCount;
                          byte serListTypeTag = serList[offset];
                          if (serListTypeTag == ATypeTag.SERIALIZED_ORDEREDLIST_TYPE_TAG) {
                              itemCount = AOrderedListSerializerDeserializer.getNumberOfItems(serList, offset);
                          } else if (serListTypeTag == ATypeTag.SERIALIZED_UNORDEREDLIST_TYPE_TAG) {
                              itemCount = AUnorderedListSerializerDeserializer.getNumberOfItems(serList, offset);
                          } else {
                              throw new TypeMismatchException(sourceLoc, BuiltinFunctions.GET_ITEM, 0, serListTypeTag,
                                      ATypeTag.SERIALIZED_ORDEREDLIST_TYPE_TAG,
                                      ATypeTag.SERIALIZED_UNORDEREDLIST_TYPE_TAG);
                          }
  
                          int itemIndex = ATypeHierarchy.getIntegerValue(BuiltinFunctions.GET_ITEM.getName(), 0,
                                  indexBytes, indexOffset);
  
                          if (itemIndex < 0) {
                              itemIndex = itemCount + itemIndex;
                          }
  
                          if (itemIndex < 0 || itemIndex >= itemCount) {
                              // Out-of-bound index access should return MISSING.
                              result.set(missingBytes, 0, 1);
                              return;
                          }
  
                          byte serItemTypeTag = serList[offset + 1];
                          ATypeTag itemTag = EnumDeserializer.ATYPETAGDESERIALIZER.deserialize(serItemTypeTag);
                          boolean selfDescList = itemTag == ATypeTag.ANY;
  
                          int itemOffset = serListTypeTag == ATypeTag.SERIALIZED_ORDEREDLIST_TYPE_TAG
                                  ? AOrderedListSerializerDeserializer.getItemOffset(serList, offset, itemIndex)
                                  : AUnorderedListSerializerDeserializer.getItemOffset(serList, offset, 0);
  
                          if (selfDescList) {
                              itemTag = EnumDeserializer.ATYPETAGDESERIALIZER.deserialize(serList[itemOffset]);
                              int itemLength =
                                      NonTaggedFormatUtil.getFieldValueLength(serList, itemOffset, itemTag, true) + 1;
                              result.set(serList, itemOffset, itemLength);
                          } else {
                              int itemLength =
                                      NonTaggedFormatUtil.getFieldValueLength(serList, itemOffset, itemTag, false);
                              resultStorage.reset();
                              output.writeByte(serItemTypeTag);
                              output.write(serList, itemOffset, itemLength);
                              result.set(resultStorage);
                          }
                      } catch (IOException e) {
                          throw HyracksDataException.create(e);
                      }
                  }
              };
          }
  
      }
  
  }
  