bubulalabu commented on code in PR #18019:
URL: https://github.com/apache/datafusion/pull/18019#discussion_r2443307448
##########
datafusion/expr-common/src/signature.rs:
##########
@@ -996,13 +1159,119 @@ impl Signature {
},
),
volatility,
+ parameter_names: None,
}
}
/// Specialized [Signature] for ArrayEmpty and similar functions.
pub fn array(volatility: Volatility) -> Self {
Signature::arrays(1, Some(ListCoercion::FixedSizedListToList),
volatility)
}
+
+ /// Add parameter names to this signature, enabling named argument
notation.
+ ///
+ /// # Example
+ /// ```
+ /// # use datafusion_expr_common::signature::{Signature, Volatility};
+ /// # use arrow::datatypes::DataType;
+ /// let sig = Signature::exact(vec![DataType::Int32, DataType::Utf8],
Volatility::Immutable)
+ /// .with_parameter_names(vec!["count".to_string(),
"name".to_string()]);
+ /// ```
+ ///
+ /// # Errors
+ /// Returns an error if the number of parameter names doesn't match the
signature's arity.
+ /// For signatures with variable arity (e.g., `Variadic`, `VariadicAny`),
parameter names
+ /// cannot be specified.
+ pub fn with_parameter_names(
+ mut self,
+ names: Vec<String>,
+ ) -> datafusion_common::Result<Self> {
+ // Validate that the number of names matches the signature
+ self.validate_parameter_names(&names)?;
+ self.parameter_names = Some(names);
+ Ok(self)
+ }
+
+ /// Validate that parameter names are compatible with this signature
+ fn validate_parameter_names(
+ &self,
+ names: &[String],
+ ) -> datafusion_common::Result<()> {
+ // Get expected argument count from the type signature
+ let expected_count = match &self.type_signature {
+ TypeSignature::Exact(types) => Some(types.len()),
+ TypeSignature::Uniform(count, _) => Some(*count),
+ TypeSignature::Numeric(count) => Some(*count),
+ TypeSignature::String(count) => Some(*count),
+ TypeSignature::Comparable(count) => Some(*count),
+ TypeSignature::Any(count) => Some(*count),
+ TypeSignature::Coercible(types) => Some(types.len()),
+ TypeSignature::Nullary => Some(0),
+ TypeSignature::ArraySignature(ArrayFunctionSignature::Array {
+ arguments,
+ ..
+ }) => Some(arguments.len()),
+
TypeSignature::ArraySignature(ArrayFunctionSignature::RecursiveArray) => {
+ Some(1)
+ }
+ TypeSignature::ArraySignature(ArrayFunctionSignature::MapArray) =>
Some(1),
+ // For OneOf, get the maximum arity from all variants
+ TypeSignature::OneOf(variants) => {
+ // Get max arity from all variants
+ let max_arity = variants
+ .iter()
+ .filter_map(|v| match v {
+ TypeSignature::Any(count)
+ | TypeSignature::Uniform(count, _)
+ | TypeSignature::Numeric(count)
+ | TypeSignature::String(count)
+ | TypeSignature::Comparable(count) => Some(*count),
+ TypeSignature::Exact(types) => Some(types.len()),
+ TypeSignature::Coercible(types) => Some(types.len()),
+ TypeSignature::Nullary => Some(0),
+ _ => None,
+ })
+ .max();
+ max_arity
+ }
+ // Variable arity signatures cannot have parameter names
+ TypeSignature::Variadic(_)
+ | TypeSignature::VariadicAny
+ | TypeSignature::UserDefined => None,
+ };
+
+ if let Some(expected) = expected_count {
+ if names.len() != expected {
+ return datafusion_common::plan_err!(
+ "Parameter names count ({}) does not match signature arity
({})",
+ names.len(),
+ expected
+ );
+ }
+ } else {
+ // For UserDefined signatures, allow parameter names
+ // The function implementer is responsible for validating the
names match the actual arguments
+ if !matches!(self.type_signature, TypeSignature::UserDefined) {
+ return datafusion_common::plan_err!(
Review Comment:
done
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