Function first_value

src/expr/src/relation/func.rs:897–911

The expected input is in the format of [((OriginalRow, InputValue), OrderByExprs...)]

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

/// The expected input is in the format of [((OriginalRow, InputValue), OrderByExprs...)]
fn first_value<'a, I>(
    datums: I,
    callers_temp_storage: &'a RowArena,
    order_by: &[ColumnOrder],
    window_frame: &WindowFrame,
) -> Datum<'a>
where
    I: IntoIterator<Item = Datum<'a>>,
{
    let temp_storage = RowArena::new();
    let iter = first_value_no_list(datums, &temp_storage, order_by, window_frame);
    callers_temp_storage.make_datum(|packer| {
        packer.push_list(iter);
    })
}

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