add byte_buf

Author: UBarney

datafusion/functions/src/unicode/reverse.rs

@@ -120,15 +120,17 @@ fn reverse_impl<'a, T: OffsetSizeTrait, V: StringArrayType<'a>>(
     let mut builder = GenericStringBuilder::<T>::with_capacity(string_array.len(), 1024);
 
     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() {
+                // reverse bytes directly since ASCII characters are single bytes
+                byte_buf.extend(s.as_bytes());
+                byte_buf.reverse();
                 // SAFETY: Since the original string was ASCII, reversing the bytes still results in valid UTF-8.
-                let reversed = unsafe {
-                    // reverse bytes directly since ASCII characters are single bytes
-                    String::from_utf8_unchecked(s.bytes().rev().collect::<Vec<u8>>())
-                };
+                let reversed = unsafe { std::str::from_utf8_unchecked(&byte_buf) };
                 builder.append_value(&reversed);
+                byte_buf.clear();
             } else {
                 string_buf.extend(s.chars().rev());
                 builder.append_value(&string_buf);