Function compare_rows

datafusion/common/src/utils/mod.rs:119–145

This function compares two tuples depending on the given sort options.

(
    x: &[ScalarValue],
    y: &[ScalarValue],
    sort_options: &[SortOptions],
)

/// This function compares two tuples depending on the given sort options.
pub fn compare_rows(
    x: &[ScalarValue],
    y: &[ScalarValue],
    sort_options: &[SortOptions],
) -> Result<Ordering> {
    let zip_it = x.iter().zip(y.iter()).zip(sort_options.iter());
    // Preserving lexical ordering.
    for ((lhs, rhs), sort_options) in zip_it {
        // Consider all combinations of NULLS FIRST/LAST and ASC/DESC configurations.
        let result = match (lhs.is_null(), rhs.is_null(), sort_options.nulls_first) {
            (true, false, false) | (false, true, true) => Ordering::Greater,
            (true, false, true) | (false, true, false) => Ordering::Less,
            (false, false, _) => {
                if sort_options.descending {
                    rhs.try_cmp(lhs)?
                } else {
                    lhs.try_cmp(rhs)?
                }
            }
            (true, true, _) => continue,
        };
        if result != Ordering::Equal {
            return Ok(result);
        }
    }
    Ok(Ordering::Equal)
}

/// This function searches for a tuple of given values (`target`) among the given
/// rows (`item_columns`) using the bisection algorithm. It assumes that `item_columns`