Function string_to_array

src/expr/src/scalar/func/variadic.rs:1303–1346

(
    string: &'a str,
    delimiter: Option<&'a str>,
    null_string: OptionalArg<Option<&'a str>>,
    temp_storage: &'a RowArena,
)

    propagates_nulls = false
)]
fn string_to_array<'a>(
    string: &'a str,
    delimiter: Option<&'a str>,
    null_string: OptionalArg<Option<&'a str>>,
    temp_storage: &'a RowArena,
) -> Result<Datum<'a>, EvalError> {
    if string.is_empty() {
        let mut row = Row::default();
        let mut packer = row.packer();
        packer.try_push_array(&[], std::iter::empty::<Datum>())?;

        return Ok(temp_storage.push_unary_row(row));
    }

    let Some(delimiter) = delimiter else {
        let split_all_chars_delimiter = "";
        return string_to_array_impl(
            string,
            split_all_chars_delimiter,
            null_string.flatten(),
            temp_storage,
        );
    };

    if delimiter.is_empty() {
        let mut row = Row::default();
        let mut packer = row.packer();
        let dims = &[ArrayDimension {
            lower_bound: 1,
            length: 1,
        }];
        match null_string.flatten() {
            Some(null_string) if null_string == string => {
                packer.try_push_array(dims, std::iter::once(Datum::Null))?;
            }
            _ => {
                packer.try_push_array(dims, vec![string].into_iter().map(Datum::String))?;
            }
        }
        Ok(temp_storage.push_unary_row(row))
    } else {
        string_to_array_impl(string, delimiter, null_string.flatten(), temp_storage)
    }
}

fn string_to_array_impl<'a>(
    string: &str,