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.unnestingfunctions.std;
  
  import java.io.IOException;
  
  import org.apache.asterix.om.exceptions.ExceptionUtil;
  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.runtime.evaluators.common.ListAccessor;
  import org.apache.asterix.runtime.unnestingfunctions.base.AbstractUnnestingFunctionDynamicDescriptor;
  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.algebricks.runtime.base.IUnnestingEvaluator;
  import org.apache.hyracks.algebricks.runtime.base.IUnnestingEvaluatorFactory;
  import org.apache.hyracks.api.context.IEvaluatorContext;
  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;
  
  public class ScanCollectionDescriptor extends AbstractUnnestingFunctionDynamicDescriptor {
  
      private static final long serialVersionUID = 1L;
      public static final IFunctionDescriptorFactory FACTORY = ScanCollectionDescriptor::new;
  
      @Override
      public FunctionIdentifier getIdentifier() {
          return BuiltinFunctions.SCAN_COLLECTION;
      }
  
      @Override
      public IUnnestingEvaluatorFactory createUnnestingEvaluatorFactory(final IScalarEvaluatorFactory[] args) {
          return new ScanCollectionUnnestingFunctionFactory(args[0], sourceLoc, getIdentifier());
      }
  
      public static class ScanCollectionUnnestingFunctionFactory implements IUnnestingEvaluatorFactory {
  
          private static final long serialVersionUID = 1L;
          private IScalarEvaluatorFactory listEvalFactory;
          private final SourceLocation sourceLoc;
          private final FunctionIdentifier funID;
  
          public ScanCollectionUnnestingFunctionFactory(IScalarEvaluatorFactory arg, SourceLocation sourceLoc,
                  FunctionIdentifier funID) {
              this.listEvalFactory = arg;
              this.sourceLoc = sourceLoc;
              this.funID = funID;
          }
  
          public IScalarEvaluatorFactory getListEvalFactory() {
              return listEvalFactory;
          }
  
          public SourceLocation getSourceLoc() {
              return sourceLoc;
          }
  
          public FunctionIdentifier getFunID() {
              return funID;
          }
  
          @Override
          public IUnnestingEvaluator createUnnestingEvaluator(IEvaluatorContext ctx) throws HyracksDataException {
              return new IUnnestingEvaluator() {
                  private final ArrayBackedValueStorage resultStorage = new ArrayBackedValueStorage();
                  private final ListAccessor listAccessor = new ListAccessor();
                  private final IPointable inputVal = new VoidPointable();
                  private final IScalarEvaluator argEval = listEvalFactory.createScalarEvaluator(ctx);
                  private int itemIndex;
                  private boolean metUnknown = false;
  
                  @Override
                  public void init(IFrameTupleReference tuple) throws HyracksDataException {
                      metUnknown = false;
                      argEval.evaluate(tuple, inputVal);
                      byte typeTag = inputVal.getByteArray()[inputVal.getStartOffset()];
                      if (typeTag == ATypeTag.SERIALIZED_MISSING_TYPE_TAG
                              || typeTag == ATypeTag.SERIALIZED_NULL_TYPE_TAG) {
                          metUnknown = true;
                          return;
                      }
                      if (typeTag != ATypeTag.SERIALIZED_ORDEREDLIST_TYPE_TAG
                              && typeTag != ATypeTag.SERIALIZED_UNORDEREDLIST_TYPE_TAG) {
                          ExceptionUtil.warnTypeMismatch(ctx, sourceLoc, funID, typeTag, 0, ATypeTag.MULTISET);
                          metUnknown = true;
                          return;
                      }
                      listAccessor.reset(inputVal.getByteArray(), inputVal.getStartOffset());
                      itemIndex = 0;
                  }
  
                  @Override
                  public boolean step(IPointable result) throws HyracksDataException {
                      try {
                          if (!metUnknown) {
                              if (itemIndex < listAccessor.size()) {
                                  resultStorage.reset();
                                  listAccessor.writeItem(itemIndex, resultStorage.getDataOutput());
                                  result.set(resultStorage);
                                  ++itemIndex;
                                  return true;
                              }
                          }
                      } catch (IOException e) {
                          throw HyracksDataException.create(e);
                      }
                      return false;
                  }
              };
          }
  
      }
  }
  