Function create_udwf_window_expr

datafusion/physical-plan/src/windows/mod.rs:170–206

Creates a `StandardWindowFunctionExpr` suitable for a user defined window function

(
    fun: &Arc<WindowUDF>,
    args: &[Arc<dyn PhysicalExpr>],
    input_schema: &Schema,
    name: String,
    ignore_nulls: bool,
)

/// Creates a `StandardWindowFunctionExpr` suitable for a user defined window function
pub fn create_udwf_window_expr(
    fun: &Arc<WindowUDF>,
    args: &[Arc<dyn PhysicalExpr>],
    input_schema: &Schema,
    name: String,
    ignore_nulls: bool,
) -> Result<Arc<dyn StandardWindowFunctionExpr>> {
    // need to get the types into an owned vec for some reason
    let input_fields: Vec<_> = args
        .iter()
        .map(|arg| arg.return_field(input_schema))
        .collect::<Result<_>>()?;

    let udwf_expr = Arc::new(WindowUDFExpr {
        fun: Arc::clone(fun),
        args: args.to_vec(),
        input_fields,
        name,
        is_reversed: false,
        ignore_nulls,
    });

    // Early validation of input expressions
    // We create a partition evaluator because in the user-defined window
    // implementation this is where code for parsing input expressions
    // exist. The benefits are:
    // - If any of the input expressions are invalid we catch them early
    // in the planning phase, rather than during execution.
    // - Maintains compatibility with built-in (now removed) window
    // functions validation behavior.
    // - Predictable and reliable error handling.
    // See discussion here:
    // https://github.com/apache/datafusion/pull/13201#issuecomment-2454209975
    let _ = udwf_expr.create_evaluator()?;

    Ok(udwf_expr)
}

/// Implements [`StandardWindowFunctionExpr`] for [`WindowUDF`]
#[derive(Clone, Debug)]