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.records;
  
  import java.io.DataOutput;
  import java.io.IOException;
  import java.util.List;
  
  import org.apache.asterix.om.pointables.ARecordVisitablePointable;
  import org.apache.asterix.om.pointables.base.DefaultOpenFieldType;
  import org.apache.asterix.om.pointables.base.IVisitablePointable;
  import org.apache.asterix.om.pointables.cast.ACastVisitor;
  import org.apache.asterix.om.pointables.cast.CastResult;
  import org.apache.asterix.om.types.ARecordType;
  import org.apache.asterix.om.types.ATypeTag;
  import org.apache.asterix.om.types.IAType;
  import org.apache.asterix.runtime.evaluators.functions.PointableHelper;
  import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluator;
  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;
  
  class RecordUnwrapEvaluator implements IScalarEvaluator {
  
      private final IPointable inputRecordPointable = new VoidPointable();
      private final IScalarEvaluator eval0;
      private ARecordVisitablePointable inputRecordVisitable;
      private final ARecordVisitablePointable openRecord;
      private boolean requiresCast = false;
      private ACastVisitor castVisitor;
      private CastResult castResult;
      private final ArrayBackedValueStorage resultStorage = new ArrayBackedValueStorage();
      private final DataOutput resultOutput = resultStorage.getDataOutput();
  
      RecordUnwrapEvaluator(IScalarEvaluator eval0, ARecordType recordType) {
          this.eval0 = eval0;
          openRecord = new ARecordVisitablePointable(DefaultOpenFieldType.NESTED_OPEN_RECORD_TYPE);
          if (recordType != null) {
              inputRecordVisitable = new ARecordVisitablePointable(recordType);
              if (hasDerivedType(recordType.getFieldTypes())) {
                  requiresCast = true;
                  castVisitor = new ACastVisitor();
                  castResult = new CastResult(openRecord, openRecord.getInputRecordType());
              }
          }
      }
  
      @Override
      public void evaluate(IFrameTupleReference tuple, IPointable result) throws HyracksDataException {
          resultStorage.reset();
          eval0.evaluate(tuple, inputRecordPointable);
  
          if (PointableHelper.checkAndSetMissingOrNull(result, inputRecordPointable)) {
              return;
          }
  
          final byte[] data = inputRecordPointable.getByteArray();
          final int offset = inputRecordPointable.getStartOffset();
          final byte typeTag = data[offset];
          if (typeTag != ATypeTag.SERIALIZED_RECORD_TYPE_TAG) {
              PointableHelper.setNull(result);
              return;
          }
          final ARecordVisitablePointable inputRecordVisitablePointable = getInputRecordVisitablePointable();
          final List<IVisitablePointable> recValues = inputRecordVisitablePointable.getFieldValues();
          if (recValues.size() != 1) {
              PointableHelper.setNull(result);
              return;
          }
          writeValue(recValues.get(0));
          result.set(resultStorage);
      }
  
      private boolean hasDerivedType(IAType[] types) {
          for (IAType type : types) {
              if (type.getTypeTag().isDerivedType()) {
                  return true;
              }
          }
          return false;
      }
  
      private ARecordVisitablePointable getInputRecordVisitablePointable() throws HyracksDataException {
          inputRecordVisitable.set(inputRecordPointable);
          if (requiresCast) {
              return castToOpenRecord();
          }
          return inputRecordVisitable;
      }
  
      private ARecordVisitablePointable castToOpenRecord() throws HyracksDataException {
          inputRecordVisitable.accept(castVisitor, castResult);
          return openRecord;
      }
  
      private void writeValue(IVisitablePointable value) throws HyracksDataException {
          try {
              resultOutput.write(value.getByteArray(), value.getStartOffset(), value.getLength());
          } catch (IOException e) {
              throw HyracksDataException.create(e);
          }
      }
  }
  