static void mergeInto()

in src/main/java/org/apache/datasketches/quantiles/ItemsMergeImpl.java [66:125]
47 lines of code
17 McCabe index (conditional complexity)

  static <T> void mergeInto(final ItemsSketch<T> src, final ItemsSketch<T> tgt) {
    final int srcK = src.getK();
    final int tgtK = tgt.getK();
    final long srcN = src.getN();
    final long tgtN = tgt.getN();

    if (srcK != tgtK) {
      downSamplingMergeInto(src, tgt);
      return;
    }
    //The remainder of this code is for the case where the k's are equal

    final Object[] srcCombBuf     = src.getCombinedBuffer();
    final long nFinal = tgtN + srcN;

    for (int i = 0; i < src.getBaseBufferCount(); i++) { //update only the base buffer
      tgt.update((T) srcCombBuf[i]);
    }

    ItemsUpdateImpl.maybeGrowLevels(tgt, nFinal);

    final Object[] scratchBuf = new Object[2 * tgtK];

    long srcBitPattern = src.getBitPattern();
    assert srcBitPattern == (srcN / (2L * srcK));

    for (int srcLvl = 0; srcBitPattern != 0L; srcLvl++, srcBitPattern >>>= 1) {
      if ((srcBitPattern & 1L) > 0L) { //only one level above base buffer
        ItemsUpdateImpl.inPlacePropagateCarry(
            srcLvl,
            (T[]) srcCombBuf, (2 + srcLvl) * tgtK,
            (T[]) scratchBuf, 0,
            false,
            tgt);
      // won't update tgt.n_ until the very end
      }
    }
    tgt.n_ = nFinal;

    assert (tgt.getN() / (2L * tgtK)) == tgt.getBitPattern(); // internal consistency check

    final T srcMax = src.isEmpty() ? null : src.getMaxItem();
    final T srcMin = src.isEmpty() ? null : src.getMinItem();
    final T tgtMax = tgt.isEmpty() ? null : tgt.getMaxItem();
    final T tgtMin = tgt.isEmpty() ? null : tgt.getMinItem();

    if ((srcMax != null) && (tgtMax != null)) {
      tgt.maxItem_ = (src.getComparator().compare(srcMax, tgtMax) > 0) ? srcMax : tgtMax;
    } //only one could be null
    else if (tgtMax == null) { //if srcMax were null we would leave tgt alone
      tgt.maxItem_ = srcMax;
    }

    if ((srcMin != null) && (tgtMin != null)) {
      tgt.minItem_ = (src.getComparator().compare(srcMin, tgtMin) > 0) ? tgtMin : srcMin;
    } //only one could be null
    else if (tgtMin == null) { //if srcMin were null we would leave tgt alone
      tgt.minItem_ = srcMin;
    }
  }