Function nullif_func

datafusion/functions/src/core/nullif.rs:112–149

Implements NULLIF(expr1, expr2) Args: 0 - left expr is any array 1 - if the left is equal to this expr2, then the result is NULL, otherwise left value is passed.

(args: &[ColumnarValue])

/// Args: 0 - left expr is any array
///       1 - if the left is equal to this expr2, then the result is NULL, otherwise left value is passed.
fn nullif_func(args: &[ColumnarValue]) -> Result<ColumnarValue> {
    let [lhs, rhs] = take_function_args("nullif", args)?;
    let is_nested = lhs.data_type().is_nested();

    match (lhs, rhs) {
        (ColumnarValue::Array(lhs), ColumnarValue::Scalar(rhs)) => {
            let rhs = rhs.to_scalar()?;
            let eq_array = compare_with_eq(lhs, &rhs, is_nested)?;
            let array = nullif(lhs, &eq_array)?;

            Ok(ColumnarValue::Array(array))
        }
        (ColumnarValue::Array(lhs), ColumnarValue::Array(rhs)) => {
            let eq_array = compare_with_eq(lhs, rhs, is_nested)?;
            let array = nullif(lhs, &eq_array)?;
            Ok(ColumnarValue::Array(array))
        }
        (ColumnarValue::Scalar(lhs), ColumnarValue::Array(rhs)) => {
            let lhs_s = lhs.to_scalar()?;
            let lhs_a = lhs.to_array_of_size(rhs.len())?;
            let eq_array = compare_with_eq(&lhs_s, rhs, is_nested)?;
            let array = nullif(
                // nullif in arrow-select does not support Datum, so we need to convert to array
                lhs_a.as_ref(),
                &eq_array,
            )?;
            Ok(ColumnarValue::Array(array))
        }
        (ColumnarValue::Scalar(lhs), ColumnarValue::Scalar(rhs)) => {
            let val: ScalarValue = match lhs.eq(rhs) {
                true => lhs.data_type().try_into()?,
                false => lhs.clone(),
            };

            Ok(ColumnarValue::Scalar(val))
        }
    }
}

#[cfg(test)]
mod tests {