nirandaperera commented on a change in pull request #10317:
URL: https://github.com/apache/arrow/pull/10317#discussion_r633855837
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File path: cpp/src/arrow/compute/kernels/scalar_string.cc
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@@ -266,6 +271,56 @@ void EnsureLookupTablesFilled() {}
#endif // ARROW_WITH_UTF8PROC
+template <typename Type>
+struct AsciiReverse : StringTransform<Type, AsciiReverse<Type>> {
+ using Base = StringTransform<Type, AsciiReverse<Type>>;
+ using offset_type = typename Base::offset_type;
+
+ bool Transform(const uint8_t* input, offset_type input_string_ncodeunits,
+ uint8_t* output, offset_type* output_written) {
+ uint8_t utf8_char_found = 0;
+ for (offset_type i = 0; i < input_string_ncodeunits; i++) {
+ // if a utf8 char is found, report to utf8_char_found
+ utf8_char_found |= input[i] & 0x80;
+ output[input_string_ncodeunits - i - 1] = input[i];
+ }
+ *output_written = input_string_ncodeunits;
+ return utf8_char_found == 0;
+ }
+
+ static Status InvalidStatus() { return Status::Invalid("Non-ascii sequence
in input"); }
Review comment:
I am reusing the `StringTransform` class for both ascii and utf8
kernels. In that, it always throws a `Status::Invalid("Invalid UTF8 sequence in
input")` which is not quite right for an ascii kernel. That's why it was
generalized and offloaded to `Derived::InvalidStatus()` :slightly_smiling_face:
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