Function fused_value_window_func

src/expr/src/relation/func.rs:1173–1187

Executes `FusedValueWindowFunc` on a reduction group. The expected input is in the format of `[((OriginalRow, (Args1, Args2, ...)), OrderByExprs...)]` where `Args1`, `Args2`, are the arguments of each of the fused functions. For functions that have only a single argument (first_value/last_value), these are simple values. For functions that have multiple arguments (lag/lead), these are also records

(
    input_datums: I,
    callers_temp_storage: &'a RowArena,
    funcs: &Vec<AggregateFunc>,
    order_by: &Vec<ColumnOrder>,
)

/// have only a single argument (first_value/last_value), these are simple values. For functions
/// that have multiple arguments (lag/lead), these are also records.
fn fused_value_window_func<'a, I>(
    input_datums: I,
    callers_temp_storage: &'a RowArena,
    funcs: &Vec<AggregateFunc>,
    order_by: &Vec<ColumnOrder>,
) -> Datum<'a>
where
    I: IntoIterator<Item = Datum<'a>>,
{
    let temp_storage = RowArena::new();
    let iter = fused_value_window_func_no_list(input_datums, &temp_storage, funcs, order_by);
    callers_temp_storage.make_datum(|packer| {
        packer.push_list(iter);
    })
}

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