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new b51edffc44 Update reverse UDF to emit utf8view when input is utf8view
(#20604)
b51edffc44 is described below
commit b51edffc44f2bd10d4140d7bc063cb054e3be727
Author: Bruce Ritchie <[email protected]>
AuthorDate: Mon Mar 9 16:48:21 2026 -0400
Update reverse UDF to emit utf8view when input is utf8view (#20604)
## Which issue does this PR close?
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enhancements and this helps us generate change logs for our releases.
You can link an issue to this PR using the GitHub syntax. For example
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Part of #20585
## Rationale for this change
Functions ideally should emit strings in the same format as the input
and previously the reverse function was emitting using utf8 for input
that was in utf8view.
## What changes are included in this PR?
Code, tests.
## Are these changes tested?
Yes.
## Are there any user-facing changes?
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updated before approving the PR.
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---
datafusion/functions/src/unicode/reverse.rs | 64 ++++++++++++++--------
.../test_files/string/string_literal.slt | 15 +++++
2 files changed, 56 insertions(+), 23 deletions(-)
diff --git a/datafusion/functions/src/unicode/reverse.rs
b/datafusion/functions/src/unicode/reverse.rs
index 71a1e6842f..7b501c0a65 100644
--- a/datafusion/functions/src/unicode/reverse.rs
+++ b/datafusion/functions/src/unicode/reverse.rs
@@ -18,10 +18,11 @@
use std::any::Any;
use std::sync::Arc;
-use crate::utils::{make_scalar_function, utf8_to_str_type};
+use crate::utils::make_scalar_function;
use DataType::{LargeUtf8, Utf8, Utf8View};
use arrow::array::{
- Array, ArrayRef, AsArray, GenericStringBuilder, OffsetSizeTrait,
StringArrayType,
+ Array, ArrayRef, AsArray, LargeStringBuilder, StringArrayType,
StringBuilder,
+ StringLikeArrayBuilder, StringViewBuilder,
};
use arrow::datatypes::DataType;
use datafusion_common::{Result, exec_err};
@@ -82,7 +83,7 @@ impl ScalarUDFImpl for ReverseFunc {
}
fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> {
- utf8_to_str_type(&arg_types[0], "reverse")
+ Ok(arg_types[0].clone())
}
fn invoke_with_args(
@@ -91,8 +92,7 @@ impl ScalarUDFImpl for ReverseFunc {
) -> Result<ColumnarValue> {
let args = &args.args;
match args[0].data_type() {
- Utf8 | Utf8View => make_scalar_function(reverse::<i32>,
vec![])(args),
- LargeUtf8 => make_scalar_function(reverse::<i64>, vec![])(args),
+ Utf8 | Utf8View | LargeUtf8 => make_scalar_function(reverse,
vec![])(args),
other => {
exec_err!("Unsupported data type {other:?} for function
reverse")
}
@@ -106,21 +106,39 @@ impl ScalarUDFImpl for ReverseFunc {
/// Reverses the order of the characters in the string `reverse('abcde') =
'edcba'`.
/// The implementation uses UTF-8 code points as characters
-fn reverse<T: OffsetSizeTrait>(args: &[ArrayRef]) -> Result<ArrayRef> {
- if args[0].data_type() == &Utf8View {
- reverse_impl::<T, _>(&args[0].as_string_view())
- } else {
- reverse_impl::<T, _>(&args[0].as_string::<T>())
+fn reverse(args: &[ArrayRef]) -> Result<ArrayRef> {
+ let len = args[0].len();
+
+ match args[0].data_type() {
+ Utf8 => reverse_impl(
+ &args[0].as_string::<i32>(),
+ StringBuilder::with_capacity(len, 1024),
+ ),
+ Utf8View => reverse_impl(
+ &args[0].as_string_view(),
+ StringViewBuilder::with_capacity(len),
+ ),
+ LargeUtf8 => reverse_impl(
+ &args[0].as_string::<i64>(),
+ LargeStringBuilder::with_capacity(len, 1024),
+ ),
+ _ => unreachable!(
+ "Reverse can only be applied to Utf8View, Utf8 and LargeUtf8 types"
+ ),
}
}
-fn reverse_impl<'a, T: OffsetSizeTrait, V: StringArrayType<'a>>(
- string_array: &V,
-) -> Result<ArrayRef> {
- let mut builder =
GenericStringBuilder::<T>::with_capacity(string_array.len(), 1024);
-
+fn reverse_impl<'a, StringArrType, StringBuilderType>(
+ string_array: &StringArrType,
+ mut array_builder: StringBuilderType,
+) -> Result<ArrayRef>
+where
+ StringArrType: StringArrayType<'a>,
+ StringBuilderType: StringLikeArrayBuilder,
+{
let mut string_buf = String::new();
let mut byte_buf = Vec::<u8>::new();
+
for string in string_array.iter() {
if let Some(s) = string {
if s.is_ascii() {
@@ -129,25 +147,25 @@ fn reverse_impl<'a, T: OffsetSizeTrait, V:
StringArrayType<'a>>(
byte_buf.reverse();
// SAFETY: Since the original string was ASCII, reversing the
bytes still results in valid UTF-8.
let reversed = unsafe {
std::str::from_utf8_unchecked(&byte_buf) };
- builder.append_value(reversed);
+ array_builder.append_value(reversed);
byte_buf.clear();
} else {
string_buf.extend(s.chars().rev());
- builder.append_value(&string_buf);
+ array_builder.append_value(&string_buf);
string_buf.clear();
}
} else {
- builder.append_null();
+ array_builder.append_null();
}
}
- Ok(Arc::new(builder.finish()) as ArrayRef)
+ Ok(Arc::new(array_builder.finish()) as ArrayRef)
}
#[cfg(test)]
mod tests {
- use arrow::array::{Array, LargeStringArray, StringArray};
- use arrow::datatypes::DataType::{LargeUtf8, Utf8};
+ use arrow::array::{Array, LargeStringArray, StringArray, StringViewArray};
+ use arrow::datatypes::DataType::{LargeUtf8, Utf8, Utf8View};
use datafusion_common::{Result, ScalarValue};
use datafusion_expr::{ColumnarValue, ScalarUDFImpl};
@@ -180,8 +198,8 @@ mod tests {
vec![ColumnarValue::Scalar(ScalarValue::Utf8View($INPUT))],
$EXPECTED,
&str,
- Utf8,
- StringArray
+ Utf8View,
+ StringViewArray
);
};
}
diff --git a/datafusion/sqllogictest/test_files/string/string_literal.slt
b/datafusion/sqllogictest/test_files/string/string_literal.slt
index 6cf0221887..2272de74cf 100644
--- a/datafusion/sqllogictest/test_files/string/string_literal.slt
+++ b/datafusion/sqllogictest/test_files/string/string_literal.slt
@@ -389,6 +389,21 @@ SELECT reverse(arrow_cast('abcde', 'Utf8View'))
----
edcba
+query T
+SELECT arrow_typeof(reverse('abcde'))
+----
+Utf8
+
+query T
+SELECT arrow_typeof(reverse(arrow_cast('abcde', 'LargeUtf8')))
+----
+LargeUtf8
+
+query T
+SELECT arrow_typeof(reverse(arrow_cast('abcde', 'Utf8View')))
+----
+Utf8View
+
query T
SELECT reverse(arrow_cast('abcde', 'Dictionary(Int32, Utf8)'))
----
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