Function rank

src/expr/src/relation/func.rs:495–505

The expected input is in the format of `[((OriginalRow, [EncodedArgs]), OrderByExprs...)]` The output is in the format of `[result_value, original_row]`. See an example at `lag_lead`, where the input-output formats are similar.

(datums: I, callers_temp_storage: &'a RowArena, order_by: &[ColumnOrder])

/// The output is in the format of `[result_value, original_row]`.
/// See an example at `lag_lead`, where the input-output formats are similar.
fn rank<'a, I>(datums: I, callers_temp_storage: &'a RowArena, order_by: &[ColumnOrder]) -> Datum<'a>
where
    I: IntoIterator<Item = Datum<'a>>,
{
    let temp_storage = RowArena::new();
    let datums = rank_no_list(datums, &temp_storage, order_by);

    callers_temp_storage.make_datum(|packer| {
        packer.push_list(datums);
    })
}

/// Like `rank`, but doesn't perform the final wrapping in a list, returning an Iterator
/// instead.