public long cellToParent()

in src/main/java/com/uber/h3core/H3Core.java [715:734]

• 15 lines of code
• 4 McCabe index (conditional complexity)

  public long cellToParent(long h3, int res) {
    // This is a ported version of h3ToParent from h3core.

    int childRes = (int) ((h3 & H3_RES_MASK) >> H3_RES_OFFSET);
    if (res < 0 || res > childRes) {
      throw new IllegalArgumentException(
          String.format("res (%d) must be between 0 and %d, inclusive", res, childRes));
    } else if (res == childRes) {
      return h3;
    }

    // newRes is the bits that need to be set to set the given resolution.
    long newRes = (long) res << H3_RES_OFFSET;
    long digitMaskForRes = H3_DIGIT_MASK;
    for (int i = 0; i < res; i++) {
      digitMaskForRes >>= 3L;
    }

    return (h3 & H3_RES_MASK_NEGATIVE) | newRes | digitMaskForRes;
  }