Function splitSubcolumnName

src/DataTypes/DataTypeDynamic.cpp:853–886

Split Dynamic subcolumn name into 2 parts: type name and subcolumn of this type. We cannot simply split by '.' because type name can also contain dots. For example: Tuple(`a.b` UInt32). But in all such cases this '.' will be inside back quotes. To split subcolumn name correctly we search for the first '.' that is not inside back quotes.

/// But in all such cases this '.' will be inside back quotes. To split subcolumn name correctly
/// we search for the first '.' that is not inside back quotes.
std::pair<std::string_view, std::string_view> splitSubcolumnName(std::string_view subcolumn_name)
{
    bool inside_quotes = false;
    const char * pos = subcolumn_name.data();
    const char * end = subcolumn_name.data() + subcolumn_name.size();
    while (true)
    {
        pos = find_first_symbols<'`', '.', '\\'>(pos, end);
        if (pos == end)
            break;

        if (*pos == '`')
        {
            inside_quotes = !inside_quotes;
            ++pos;
        }
        else if (*pos == '\\')
        {
            ++pos;
        }
        else if (*pos == '.')
        {
            if (inside_quotes)
                ++pos;
            else
                break;
        }
    }

    if (pos == end)
        return {subcolumn_name, {}};

    return {std::string_view(subcolumn_name.data(), pos), std::string_view(pos + 1, end)}; /// NOLINT(bugprone-suspicious-stringview-data-usage)
}

}