Struct datafusion_expr::expr_fn::SimpleScalarUDF

pub struct SimpleScalarUDF { /* private fields */ }

Implements ScalarUDFImpl for functions that have a single signature and return type.

Implementations

impl SimpleScalarUDF

pub fn new( name: impl Into<String>, input_types: Vec<DataType>, return_type: DataType, volatility: Volatility, fun: ScalarFunctionImplementation, ) -> Self

Create a new SimpleScalarUDF from a name, input types, return type and implementation. Implementing ScalarUDFImpl allows more flexibility

Trait Implementations

impl Debug for SimpleScalarUDF

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl ScalarUDFImpl for SimpleScalarUDF

fn as_any(&self) -> &dyn Any

Returns this object as an Any trait object

fn name(&self) -> &str

Returns this function’s name

fn signature(&self) -> &Signature

Returns the function’s Signature for information about what input types are accepted and the function’s Volatility.

fn return_type(&self, _arg_types: &[DataType]) -> Result<DataType>

What DataType will be returned by this function, given the types of the arguments.

fn invoke(&self, args: &[ColumnarValue]) -> Result<ColumnarValue>

Invoke the function on args, returning the appropriate result

fn display_name(&self, args: &[Expr]) -> Result<String>

Returns the user-defined display name of the UDF given the arguments

fn return_type_from_exprs( &self, _args: &[Expr], _schema: &dyn ExprSchema, arg_types: &[DataType], ) -> Result<DataType>

What DataType will be returned by this function, given the arguments?

fn invoke_no_args(&self, _number_rows: usize) -> Result<ColumnarValue>

Invoke the function without args, instead the number of rows are provided, returning the appropriate result.

fn aliases(&self) -> &[String]

Returns any aliases (alternate names) for this function.

fn simplify( &self, args: Vec<Expr>, _info: &dyn SimplifyInfo, ) -> Result<ExprSimplifyResult>

Optionally apply per-UDF simplification / rewrite rules.

fn short_circuits(&self) -> bool

Returns true if some of this exprs subexpressions may not be evaluated and thus any side effects (like divide by zero) may not be encountered Setting this to true prevents certain optimizations such as common subexpression elimination

fn evaluate_bounds(&self, _input: &[&Interval]) -> Result<Interval>

Computes the output interval for a ScalarUDFImpl, given the input intervals.

fn propagate_constraints( &self, _interval: &Interval, _inputs: &[&Interval], ) -> Result<Option<Vec<Interval>>>

Updates bounds for child expressions, given a known interval for this function. This is used to propagate constraints down through an expression tree.

fn output_ordering(&self, _inputs: &[ExprProperties]) -> Result<SortProperties>

Calculates the SortProperties of this function based on its children’s properties.

fn coerce_types(&self, _arg_types: &[DataType]) -> Result<Vec<DataType>>

Coerce arguments of a function call to types that the function can evaluate.

fn equals(&self, other: &dyn ScalarUDFImpl) -> bool

Return true if this scalar UDF is equal to the other.

fn hash_value(&self) -> u64

Returns a hash value for this scalar UDF.