Method lambda_parameters

datafusion/expr/src/expr.rs:462–487

Invokes the inner function [`crate::HigherOrderUDFImpl::lambda_parameters`] using the arguments of this invocation. This expression lambda variables must be already resolved either by coming from the default sql planner or by calling [Expr::resolve_lambda_variables] or [LogicalPlan::resolve_lambda_variables] [LogicalPlan::resolve_lambda_variables]: crate::LogicalPlan::resolve_lambda_variables

(
        &self,
        schema: &dyn ExprSchema,
    )

    ///
    /// [LogicalPlan::resolve_lambda_variables]: crate::LogicalPlan::resolve_lambda_variables
    pub fn lambda_parameters(
        &self,
        schema: &dyn ExprSchema,
    ) -> Result<Vec<Vec<FieldRef>>> {
        let args = self
            .args
            .iter()
            .map(|e| match e {
                Expr::Lambda(lambda) => {
                    Ok(ValueOrLambda::Lambda(Some(lambda.body.to_field(schema)?.1)))
                }
                _ => Ok(ValueOrLambda::Value(e.to_field(schema)?.1)),
            })
            .collect::<Result<Vec<_>>>()?;

        let coerced_fields =
            value_fields_with_higher_order_udf(&args, self.func.as_ref())?;

        match self.func.lambda_parameters(0, &coerced_fields)? {
            LambdaParametersProgress::Partial(_) => plan_err!(
                "{} lambda_parameters returned a partial result when the return type of all it's lambdas were provided",
                self.name()
            ),
            LambdaParametersProgress::Complete(items) => Ok(items),
        }
    }
}

impl Hash for HigherOrderFunction {