Function column_name_from_number

pub fn column_name_from_number(num: usize) -> String

Maps an index number to a value, necessary for creating the column name:

0   -> A
25  -> Z
26  -> AA
27  -> AB

… and so on. This implementation is very fast, takes ~50 to 100 nanoseconds for 1 iteration due to almost pure-stack allocated data. For an explanation of the algorithm with comments, see: https://github.com/fschutt/street_index/blob/78b935a1303070947c0854b6d01f540ec298c9d5/src/gridconfig.rs#L155-L209