Struct DeclaredScalarFn 

pub struct DeclaredScalarFn { /* private fields */ }

A scalar function declared from Cypher via uni.plugin.declareFunction.

Holds a parsed Expr body, the declared argument names (in positional order — same order as the columns passed to ScalarPluginFn::invoke), and a precomputed FnSignature.

Implementations

impl DeclaredScalarFn

pub fn new(body: Expr, arg_names: Vec<String>, signature: FnSignature) -> Self

Construct a declared scalar function.

arg_names must align with the positional arguments — element 0 of arg_names corresponds to column 0 in the invocation’s args slice.

pub fn build_signature( returns: DataType, args: &[(String, DataType)], ) -> FnSignature

Construct a default FnSignature given an Arrow return type and a list of (name, type) pairs for arguments.

Trait Implementations

impl Debug for DeclaredScalarFn

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

Formats the value using the given formatter.

impl ScalarPluginFn for DeclaredScalarFn

fn signature(&self) -> &FnSignature

The function’s static signature (arg types, return type, volatility).

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

Invoke the function on a batch of inputs.