alamb commented on code in PR #3912:
URL: https://github.com/apache/arrow-rs/pull/3912#discussion_r1146547284
##########
arrow-ord/src/comparison.rs:
##########
@@ -893,14 +875,8 @@ pub fn lt_eq_dyn_binary_scalar(
right: &[u8],
) -> Result<BooleanArray, ArrowError> {
match left.data_type() {
- DataType::Binary => {
- let left = as_generic_binary_array::<i32>(left);
- lt_eq_binary_scalar(left, right)
- }
- DataType::LargeBinary => {
- let left = as_generic_binary_array::<i64>(left);
- lt_eq_binary_scalar(left, right)
- }
+ DataType::Binary => lt_eq_binary_scalar(left.as_binary::<i32>(),
right),
Review Comment:
it sure looks nicer
##########
arrow-array/src/cast.rs:
##########
@@ -709,6 +709,165 @@ where
T::from(array.to_data())
}
+mod private {
+ pub trait Sealed {}
+}
+
+/// An extension trait for `dyn Array` that provides ergonomic downcasting
+///
+/// ```
+/// # use std::sync::Arc;
+/// # use arrow_array::{ArrayRef, Int32Array};
+/// # use arrow_array::cast::AsArray;
+/// # use arrow_array::types::Int32Type;
+/// let col = Arc::new(Int32Array::from(vec![1, 2, 3])) as ArrayRef;
+/// assert_eq!(col.as_primitive::<Int32Type>().values(), &[1, 2, 3]);
+/// ```
+pub trait AsArray: private::Sealed {
+ /// Downcast this to a [`BooleanArray`] returning `None` if not possible
+ fn as_boolean_opt(&self) -> Option<&BooleanArray>;
+
+ /// Downcast this to a [`BooleanArray`] panicking if not possible
+ fn as_boolean(&self) -> &BooleanArray {
+ self.as_boolean_opt().expect("boolean array")
+ }
+
+ /// Downcast this to a [`PrimitiveArray`] returning `None` if not possible
+ fn as_primitive_opt<T: ArrowPrimitiveType>(&self) ->
Option<&PrimitiveArray<T>>;
+
+ /// Downcast this to a [`PrimitiveArray`] panicking if not possible
+ fn as_primitive<T: ArrowPrimitiveType>(&self) -> &PrimitiveArray<T> {
+ self.as_primitive_opt().expect("primitive array")
+ }
+
+ /// Downcast this to a [`GenericByteArray`] returning `None` if not
possible
+ fn as_bytes_opt<T: ByteArrayType>(&self) -> Option<&GenericByteArray<T>>;
+
+ /// Downcast this to a [`GenericByteArray`] panicking if not possible
+ fn as_bytes<T: ByteArrayType>(&self) -> &GenericByteArray<T> {
+ self.as_bytes_opt().expect("byte array")
+ }
+
+ /// Downcast this to a [`GenericStringArray`] returning `None` if not
possible
+ fn as_string_opt<O: OffsetSizeTrait>(&self) ->
Option<&GenericStringArray<O>> {
+ self.as_bytes_opt()
+ }
+
+ /// Downcast this to a [`GenericStringArray`] panicking if not possible
+ fn as_string<O: OffsetSizeTrait>(&self) -> &GenericStringArray<O> {
+ self.as_bytes_opt().expect("string array")
+ }
+
+ /// Downcast this to a [`GenericBinaryArray`] returning `None` if not
possible
+ fn as_binary_opt<O: OffsetSizeTrait>(&self) ->
Option<&GenericBinaryArray<O>> {
+ self.as_bytes_opt()
+ }
+
+ /// Downcast this to a [`GenericBinaryArray`] panicking if not possible
+ fn as_binary<O: OffsetSizeTrait>(&self) -> &GenericBinaryArray<O> {
+ self.as_bytes_opt().expect("binary array")
+ }
+
+ /// Downcast this to a [`StructArray`] returning `None` if not possible
+ fn as_struct_opt(&self) -> Option<&StructArray>;
+
+ /// Downcast this to a [`StructArray`] panicking if not possible
+ fn as_struct(&self) -> &StructArray {
+ self.as_struct_opt().expect("struct array")
+ }
+
+ /// Downcast this to a [`GenericListArray`] returning `None` if not
possible
+ fn as_list_opt<O: OffsetSizeTrait>(&self) -> Option<&GenericListArray<O>>;
+
+ /// Downcast this to a [`GenericListArray`] panicking if not possible
+ fn as_list<O: OffsetSizeTrait>(&self) -> &GenericListArray<O> {
+ self.as_list_opt().expect("list array")
+ }
+
+ /// Downcast this to a [`MapArray`] returning `None` if not possible
+ fn as_map_opt(&self) -> Option<&MapArray>;
+
+ /// Downcast this to a [`MapArray`] panicking if not possible
+ fn as_map(&self) -> &MapArray {
+ self.as_map_opt().expect("map array")
+ }
+
+ /// Downcast this to a [`DictionaryArray`] returning `None` if not possible
+ fn as_dictionary_opt<K: ArrowDictionaryKeyType>(&self)
+ -> Option<&DictionaryArray<K>>;
+
+ /// Downcast this to a [`DictionaryArray`] panicking if not possible
+ fn as_dictionary<K: ArrowDictionaryKeyType>(&self) -> &DictionaryArray<K> {
+ self.as_dictionary_opt().expect("dictionary array")
+ }
+}
+
+impl private::Sealed for dyn Array + '_ {}
+impl AsArray for dyn Array + '_ {
+ fn as_boolean_opt(&self) -> Option<&BooleanArray> {
+ self.as_any().downcast_ref()
Review Comment:
this is very clever 👍
##########
arrow-array/src/builder/generic_byte_run_builder.rs:
##########
@@ -368,7 +368,7 @@ pub type LargeStringRunBuilder<K> =
GenericByteRunBuilder<K, LargeUtf8Type>;
///
/// // Values are polymorphic and so require a downcast.
/// let av = array.values();
-/// let ava: &BinaryArray = as_generic_binary_array::<i32>(av.as_ref());
+/// let ava: &BinaryArray = av.as_binary();
Review Comment:
this is much nicer -- I hit this with @appletreeisyellow when trying to
downcast to a `BinaryArray` (having to know to put i32 was non obvious)
##########
arrow-array/src/cast.rs:
##########
@@ -709,6 +709,165 @@ where
T::from(array.to_data())
}
+mod private {
+ pub trait Sealed {}
+}
+
+/// An extension trait for `dyn Array` that provides ergonomic downcasting
+///
+/// ```
+/// # use std::sync::Arc;
+/// # use arrow_array::{ArrayRef, Int32Array};
+/// # use arrow_array::cast::AsArray;
+/// # use arrow_array::types::Int32Type;
+/// let col = Arc::new(Int32Array::from(vec![1, 2, 3])) as ArrayRef;
+/// assert_eq!(col.as_primitive::<Int32Type>().values(), &[1, 2, 3]);
+/// ```
+pub trait AsArray: private::Sealed {
+ /// Downcast this to a [`BooleanArray`] returning `None` if not possible
+ fn as_boolean_opt(&self) -> Option<&BooleanArray>;
Review Comment:
I like how you have provided both `_opt` and non `_opt` variants so users
can choose
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