Struct HigherOrderSignature 

pub struct HigherOrderSignature {
    pub type_signature: HigherOrderTypeSignature,
    pub volatility: Volatility,
    pub lambda_parameters_max_iterations: usize,
}

Provides information necessary for calling a higher order function.

• HigherOrderTypeSignature defines the argument types that a function has implementations for.

• Volatility defines how the output of the function changes with the input.

Fields

type_signature: HigherOrderTypeSignature

The data types that the function accepts. See HigherOrderTypeSignature for more information.

volatility: Volatility

The volatility of the function. See Volatility for more information.

lambda_parameters_max_iterations: usize

The max number of times to call HigherOrderUDFImpl::lambda_parameters before raising an error. Used to guard against implementations that causes an infinite loop by endlessly returning LambdaParametersProgress::Partial. Defaults to 256

Implementations

impl HigherOrderSignature

pub fn new( type_signature: HigherOrderTypeSignature, volatility: Volatility, ) -> Self

Creates a new HigherOrderSignature from a given type signature and volatility.

pub fn user_defined(volatility: Volatility) -> Self

User-defined coercion rules for the function.

pub fn variadic_any(volatility: Volatility) -> Self

An arbitrary number of lambdas or arguments of any type.

pub fn any(arg_count: usize, volatility: Volatility) -> Self

A specified number of arguments of any type

pub fn exact(args: Vec<ValueOrLambda<(), ()>>, volatility: Volatility) -> Self

Exactly the specified arguments in the given order, with arbitrary types. DataFusion will call HigherOrderUDFImpl::coerce_value_types to prepare the value argument types.

Example

A function that takes one value argument followed by one lambda:

let sig = HigherOrderSignature::exact(
    vec![ValueOrLambda::Value(()), ValueOrLambda::Lambda(())],
    Volatility::Immutable,
);

Trait Implementations

impl Clone for HigherOrderSignature

fn clone(&self) -> HigherOrderSignature

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for HigherOrderSignature

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

Formats the value using the given formatter.

impl Eq for HigherOrderSignature

impl Hash for HigherOrderSignature

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for HigherOrderSignature

fn eq(&self, other: &HigherOrderSignature) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for HigherOrderSignature

fn partial_cmp(&self, other: &HigherOrderSignature) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl StructuralPartialEq for HigherOrderSignature