void iterStepChild()

in h3_iterators.c [250:287]

• 23 lines of code
• 7 McCabe index (conditional complexity)

void iterStepChild(IterCellsChildren *it) {
    // once h == H3_NULL, the iterator returns an infinite sequence of H3_NULL
    if (it->h == H3_NULL) return;

    int childRes = H3_GET_RESOLUTION(it->h);

    _incrementResDigit(it, childRes);

    for (int i = childRes; i >= it->_parentRes; i--) {
        if (i == it->_parentRes) {
            // if we're modifying the parent resolution digit, then we're done
            *it = _null_iter();
            return;
        }

        // PENTAGON_SKIPPED_DIGIT == 1
        if (i == it->_skipDigit &&
            _getResDigit(it, i) == PENTAGON_SKIPPED_DIGIT) {
            // Then we are iterating through the children of a pentagon cell.
            // All children of a pentagon have the property that the first
            // nonzero digit between the parent and child resolutions is
            // not 1.
            // I.e., we never see a sequence like 00001.
            // Thus, we skip the `1` in this digit.
            _incrementResDigit(it, i);
            it->_skipDigit -= 1;
            return;
        }

        // INVALID_DIGIT == 7
        if (_getResDigit(it, i) == INVALID_DIGIT) {
            _incrementResDigit(
                it, i);  // zeros out it[i] and increments it[i-1] by 1
        } else {
            break;
        }
    }
}