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 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.base.AbstractScalarFunctionDynamicDescriptor;
  import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
  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.dataflow.common.data.accessors.IFrameTupleReference;
  
  public final class IfMissingOrNullDescriptor extends AbstractScalarFunctionDynamicDescriptor {
  
      private static final long serialVersionUID = 1L;
      public static final IFunctionDescriptorFactory FACTORY = IfMissingOrNullDescriptor::new;
  
      @Override
      public IScalarEvaluatorFactory createEvaluatorFactory(IScalarEvaluatorFactory[] args) throws AlgebricksException {
          return new IScalarEvaluatorFactory() {
              private static final long serialVersionUID = 1L;
  
              @Override
              public IScalarEvaluator createScalarEvaluator(final IEvaluatorContext ctx) throws HyracksDataException {
                  return new AbstractIfMissingOrNullEval(ctx, args) {
                      @Override
                      protected boolean skip(byte argTypeTag) {
                          return argTypeTag == ATypeTag.SERIALIZED_MISSING_TYPE_TAG
                                  || argTypeTag == ATypeTag.SERIALIZED_NULL_TYPE_TAG;
                      }
                  };
              }
          };
      }
  
      @Override
      public FunctionIdentifier getIdentifier() {
          return BuiltinFunctions.IF_MISSING_OR_NULL;
      }
  
      public static abstract class AbstractIfMissingOrNullEval implements IScalarEvaluator {
  
          private final IScalarEvaluator[] argEvals;
  
          private final IPointable argPtr;
  
          AbstractIfMissingOrNullEval(IEvaluatorContext ctx, IScalarEvaluatorFactory[] args) throws HyracksDataException {
              argEvals = new IScalarEvaluator[args.length];
              for (int i = 0; i < argEvals.length; i++) {
                  argEvals[i] = args[i].createScalarEvaluator(ctx);
              }
              argPtr = new VoidPointable();
          }
  
          @Override
          public void evaluate(IFrameTupleReference tuple, IPointable result) throws HyracksDataException {
              for (IScalarEvaluator argEval : argEvals) {
                  argEval.evaluate(tuple, argPtr);
                  byte[] bytes = argPtr.getByteArray();
                  int offset = argPtr.getStartOffset();
                  if (!skip(bytes[offset])) {
                      result.set(argPtr);
                      return;
                  }
              }
              PointableHelper.setNull(result);
          }
  
          protected abstract boolean skip(byte argTypeTag);
      }
  }
  