private static void addEmptyTopLevelToCompletelyFullSketch()

in src/main/java/org/apache/datasketches/kll/KllHelper.java [822:917]
70 lines of code
9 McCabe index (conditional complexity)

  private static void addEmptyTopLevelToCompletelyFullSketch(final KllSketch sketch) {
    final SketchType sketchType = sketch.sketchType;
    final int[] myCurLevelsArr = sketch.getLevelsArray();
    final int myCurNumLevels = sketch.getNumLevels();
    final int myCurTotalItemsCapacity = myCurLevelsArr[myCurNumLevels];
    double minDouble = Double.NaN;
    double maxDouble = Double.NaN;
    float minFloat = Float.NaN;
    float maxFloat = Float.NaN;

    double[] myCurDoubleItemsArr = null;
    float[] myCurFloatItemsArr = null;

    final int myNewNumLevels;
    final int[] myNewLevelsArr;
    final int myNewTotalItemsCapacity;

    float[] myNewFloatItemsArr = null;
    double[] myNewDoubleItemsArr = null;

    if (sketchType == DOUBLES_SKETCH) {
      final KllDoublesSketch dblSk = (KllDoublesSketch) sketch;
      minDouble = dblSk.getMinDoubleItem();
      maxDouble = dblSk.getMaxDoubleItem();
      myCurDoubleItemsArr = dblSk.getDoubleItemsArray();
      //assert we are following a certain growth scheme
      assert myCurDoubleItemsArr.length == myCurTotalItemsCapacity;
    } else if (sketchType == FLOATS_SKETCH) {
      final KllFloatsSketch fltSk = (KllFloatsSketch) sketch;
      minFloat = fltSk.getMinFloatItem();
      maxFloat = fltSk.getMaxFloatItem();
      myCurFloatItemsArr = fltSk.getFloatItemsArray();
      assert myCurFloatItemsArr.length == myCurTotalItemsCapacity;
    }
//    else {
//      //ITEMS_SKETCH //TODO
//    }
    assert myCurLevelsArr[0] == 0; //definition of full is part of the growth scheme

    final int deltaItemsCap = levelCapacity(sketch.getK(), myCurNumLevels + 1, 0, sketch.getM());
    myNewTotalItemsCapacity = myCurTotalItemsCapacity + deltaItemsCap;

    // Check if growing the levels arr if required.
    // Note that merging MIGHT over-grow levels_, in which case we might not have to grow it
    final boolean growLevelsArr = myCurLevelsArr.length < myCurNumLevels + 2;

    // GROW LEVELS ARRAY
    if (growLevelsArr) {
      //grow levels arr by one and copy the old data to the new array, extra space at the top.
      myNewLevelsArr = Arrays.copyOf(myCurLevelsArr, myCurNumLevels + 2);
      assert myNewLevelsArr.length == myCurLevelsArr.length + 1;
      myNewNumLevels = myCurNumLevels + 1;
      sketch.incNumLevels(); //increment the class member
    } else {
      myNewLevelsArr = myCurLevelsArr;
      myNewNumLevels = myCurNumLevels;
    }
    // This loop updates all level indices EXCLUDING the "extra" index at the top
    for (int level = 0; level <= myNewNumLevels - 1; level++) {
      myNewLevelsArr[level] += deltaItemsCap;
    }
    myNewLevelsArr[myNewNumLevels] = myNewTotalItemsCapacity; // initialize the new "extra" index at the top

    // GROW ITEMS ARRAY
    if (sketchType == DOUBLES_SKETCH) {
      myNewDoubleItemsArr = new double[myNewTotalItemsCapacity];
      // copy and shift the current data into the new array
      System.arraycopy(myCurDoubleItemsArr, 0, myNewDoubleItemsArr, deltaItemsCap, myCurTotalItemsCapacity);
    } else if (sketchType == FLOATS_SKETCH) {
      myNewFloatItemsArr = new float[myNewTotalItemsCapacity];
      // copy and shift the current items data into the new array
      System.arraycopy(myCurFloatItemsArr, 0, myNewFloatItemsArr, deltaItemsCap, myCurTotalItemsCapacity);
    }
//    else {
//      //ITEMS_SKETCH // TODO
//    }

    //MEMORY SPACE MANAGEMENT
    if (sketch.serialVersionUpdatable) {
      sketch.wmem = memorySpaceMgmt(sketch, myNewLevelsArr.length, myNewTotalItemsCapacity);
    }
    //update our sketch with new expanded spaces
    sketch.setNumLevels(myNewNumLevels);
    sketch.setLevelsArray(myNewLevelsArr);
    if (sketchType == DOUBLES_SKETCH) {
      final KllDoublesSketch dblSk = (KllDoublesSketch) sketch;
      dblSk.setMinDoubleItem(minDouble);
      dblSk.setMaxDoubleItem(maxDouble);
      dblSk.setDoubleItemsArray(myNewDoubleItemsArr);
    } else { //Float sketch
      final KllFloatsSketch fltSk = (KllFloatsSketch) sketch;
      fltSk.setMinFloatItem(minFloat);
      fltSk.setMaxFloatItem(maxFloat);
      fltSk.setFloatItemsArray(myNewFloatItemsArr);
    }
  }