public Tuple exec()

in src/main/java/org/apache/datasketches/pig/theta/Union.java [472:519]
33 lines of code
7 McCabe index (conditional complexity)

    public Tuple exec(final Tuple inputTuple) throws IOException { //throws is in API

      final org.apache.datasketches.theta.Union union =
          SetOperation.builder().setP(this.myP_).setSeed(this.mySeed_).setResizeFactor(RF)
                  .setNominalEntries(this.myNomEntries_).buildUnion();
      final DataBag outerBag = extractBag(inputTuple); //InputTuple.bag0
      if (outerBag == null) {  //must have non-empty outer bag at field 0.
        return this.myEmptyCompactOrderedSketchTuple_;
      }
      //Bag is not empty.

      for (Tuple dataTuple : outerBag) {
        final Object f0 = extractFieldAtIndex(dataTuple, 0); //inputTuple.bag0.dataTupleN.f0
        //must have non-null field zero
        if (f0 == null) {
          continue; //go to next dataTuple if there is one.  If none, exception is thrown.
        }
        //f0 is not null
        if (f0 instanceof DataBag) {
          final DataBag innerBag = (DataBag)f0; //inputTuple.bag0.dataTupleN.f0:bag
          if (innerBag.size() == 0) {
            continue; //go to next dataTuple if there is one.  If none, exception is thrown.
          }
          //If field 0 of a dataTuple is again a Bag all tuples of this inner bag
          // will be passed into the union.
          //It is due to system bagged outputs from multiple mapper Initial functions.
          //The Intermediate stage was bypassed.
          updateUnion(innerBag, union); //process all tuples of innerBag

        }
        else if (f0 instanceof DataByteArray) { //inputTuple.bag0.dataTupleN.f0:DBA
          //If field 0 of a dataTuple is a DataByteArray we assume it is a sketch from a prior call
          //It is due to system bagged outputs from multiple mapper Intermediate functions.
          // Each dataTuple.DBA:sketch will merged into the union.
          final DataByteArray dba = (DataByteArray) f0;
          final Memory srcMem = Memory.wrap(dba.get());
          union.union(srcMem);

        }
        else { // we should never get here.
          throw new IllegalArgumentException("dataTuple.Field0: Is not a DataByteArray: "
              + f0.getClass().getName());
        }
      }

      final CompactSketch compactSketch = union.getResult(true, null);
      return compactOrderedSketchToTuple(compactSketch);
    }