polars_sql/
function_registry.rs

1//! This module defines a FunctionRegistry for supported SQL functions and UDFs.
2
3use polars_error::{PolarsResult, polars_bail};
4use polars_plan::prelude::udf::UserDefinedFunction;
5pub use polars_plan::prelude::{Context, FunctionOptions};
6/// A registry that holds user defined functions.
7pub trait FunctionRegistry: Send + Sync {
8    /// Register a function.
9    fn register(&mut self, name: &str, fun: UserDefinedFunction) -> PolarsResult<()>;
10    /// Call a user defined function.
11    fn get_udf(&self, name: &str) -> PolarsResult<Option<UserDefinedFunction>>;
12    /// Check if a function is registered.
13    fn contains(&self, name: &str) -> bool;
14}
15
16/// A default registry that does not support registering or calling functions.
17pub struct DefaultFunctionRegistry {}
18
19impl FunctionRegistry for DefaultFunctionRegistry {
20    fn register(&mut self, _name: &str, _fun: UserDefinedFunction) -> PolarsResult<()> {
21        polars_bail!(ComputeError: "'register' not implemented on DefaultFunctionRegistry'")
22    }
23
24    fn get_udf(&self, _name: &str) -> PolarsResult<Option<UserDefinedFunction>> {
25        polars_bail!(ComputeError: "'get_udf' not implemented on DefaultFunctionRegistry'")
26    }
27    fn contains(&self, _name: &str) -> bool {
28        false
29    }
30}