Function is_row_ahead

datafusion/physical-expr/src/window/window_expr.rs:573–588

This utility function checks whether `current_cols` is ahead of the `old_cols` in terms of `sort_options`.

(
    old_col: &ArrayRef,
    current_col: Option<&ArrayRef>,
    sort_options: &SortOptions,
)

/// This utility function checks whether `current_cols` is ahead of the `old_cols`
/// in terms of `sort_options`.
fn is_row_ahead(
    old_col: &ArrayRef,
    current_col: Option<&ArrayRef>,
    sort_options: &SortOptions,
) -> Result<bool> {
    let Some(current_col) = current_col else {
        return Ok(false);
    };
    if old_col.is_empty() || current_col.is_empty() {
        return Ok(false);
    }
    let last_value = ScalarValue::try_from_array(old_col, old_col.len() - 1)?;
    let current_value = ScalarValue::try_from_array(current_col, 0)?;
    let cmp = compare_rows(&[current_value], &[last_value], &[*sort_options])?;
    Ok(cmp.is_gt())
}

/// Get order by expression results inside `order_by_columns`.
pub(crate) fn get_orderby_values(order_by_columns: Vec<SortColumn>) -> Vec<ArrayRef> {