jayzhan211 commented on code in PR #9108:
URL: https://github.com/apache/arrow-datafusion/pull/9108#discussion_r1493721760
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datafusion/expr/src/signature.rs:
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@@ -123,29 +128,171 @@ pub enum TypeSignature {
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub enum ArrayFunctionSignature {
/// Specialized Signature for ArrayAppend and similar functions
- /// The first argument should be List/LargeList, and the second argument
should be non-list or list.
+ /// If `allow_null` is true, the function also accepts a single argument
of type Null.
+ /// The first argument should be List/LargeList/FixedSizedList, and the
second argument should be non-list or list.
/// The second argument's list dimension should be one dimension less than
the first argument's list dimension.
/// List dimension of the List/LargeList is equivalent to the number of
List.
/// List dimension of the non-list is 0.
- ArrayAndElement,
+ ArrayAndElement(bool),
/// Specialized Signature for ArrayPrepend and similar functions
+ /// If `allow_null` is true, the function also accepts a single argument
of type Null.
/// The first argument should be non-list or list, and the second argument
should be List/LargeList.
/// The first argument's list dimension should be one dimension less than
the second argument's list dimension.
- ElementAndArray,
- ArrayAndIndex,
+ ElementAndArray(bool),
+ /// Specialized Signature for ArrayEqual and similar functions
+ /// If `allow_null` is true, the function also accepts a single argument
of type Null.
+ /// The first argument should be List/LargeList/FixedSizedList, and the
second argument should be Int64.
+ ArrayAndIndex(bool),
+ /// Specialized Signature for ArrayEmpty and similar functions
+ /// The function takes a single argument that must be a
List/LargeList/FixedSizeList
+ /// or something that can be coerced to one of those types.
+ /// If `allow_null` is true, the function also accepts a single argument
of type Null.
+ Array(bool),
+}
+
+impl ArrayFunctionSignature {
+ /// Arguments to ArrayFunctionSignature
+ /// `current_types` - The data types of the arguments
+ /// `allow_null_coercion` - Whether null type coercion is allowed
+ /// Returns the valid types for the function signature
+ pub fn get_type_signature(
+ &self,
+ current_types: &[DataType],
+ ) -> Result<Vec<Vec<DataType>>> {
+ fn array_append_or_prepend_valid_types(
+ current_types: &[DataType],
+ is_append: bool,
+ allow_null_coercion: bool,
+ ) -> Result<Vec<Vec<DataType>>> {
+ if current_types.len() != 2 {
+ return Ok(vec![vec![]]);
+ }
+
+ let (array_type, elem_type) = if is_append {
+ (¤t_types[0], ¤t_types[1])
+ } else {
+ (¤t_types[1], ¤t_types[0])
+ };
+
+ // We follow Postgres on `array_append(Null, T)`, which is not
valid.
+ if array_type.eq(&DataType::Null) && !allow_null_coercion {
Review Comment:
is there any array function's signature is `array_and_element(true, )`? If
not, it is better not to introduce `allow_null_coercion` for now.
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