Function evaluate_predicate

datafusion/physical-expr/src/expressions/case.rs:1420–1439

Attempts to const evaluate the given `predicate`. Returns: - `Some(true)` if the predicate evaluates to a truthy value. - `Some(false)` if the predicate evaluates to a falsy value. - `None` if the predicate could not be evaluated.

(predicate: &Arc<dyn PhysicalExpr>)

/// - `Some(false)` if the predicate evaluates to a falsy value.
/// - `None` if the predicate could not be evaluated.
fn evaluate_predicate(predicate: &Arc<dyn PhysicalExpr>) -> Result<Option<bool>> {
    // Create a dummy record with no columns and one row
    let batch = RecordBatch::try_new_with_options(
        Arc::new(Schema::empty()),
        vec![],
        &RecordBatchOptions::new().with_row_count(Some(1)),
    )?;

    // Evaluate the predicate and interpret the result as a boolean
    let result = match predicate.evaluate(&batch) {
        // An error during evaluation means we couldn't const evaluate the predicate, so return `None`
        Err(_) => None,
        Ok(ColumnarValue::Array(array)) => Some(
            ScalarValue::try_from_array(array.as_ref(), 0)?
                .cast_to(&DataType::Boolean)?,
        ),
        Ok(ColumnarValue::Scalar(scalar)) => Some(scalar.cast_to(&DataType::Boolean)?),
    };
    Ok(result.map(|v| matches!(v, ScalarValue::Boolean(Some(true)))))
}

fn replace_with_null(
    expr: &Arc<dyn PhysicalExpr>,