Add support for Utf8View in arrow_string::length (#6345)

* Add support for Utf8View in arrow_string::length #6305

* Cargo fmt.

arrow-string/src/length.rs

@@ -48,7 +48,7 @@ fn bit_length_impl<P: ArrowPrimitiveType>(
 /// For list array, length is the number of elements in each list.
 /// For string array and binary array, length is the number of bytes of each value.
 ///
-/// * this only accepts ListArray/LargeListArray, StringArray/LargeStringArray, BinaryArray/LargeBinaryArray, and FixedSizeListArray,
+/// * this only accepts ListArray/LargeListArray, StringArray/LargeStringArray/StringViewArray, BinaryArray/LargeBinaryArray, and FixedSizeListArray,
 /// or DictionaryArray with above Arrays as values
 /// * length of null is null.
 pub fn length(array: &dyn Array) -> Result<ArrayRef, ArrowError> {
@@ -74,6 +74,14 @@ pub fn length(array: &dyn Array) -> Result<ArrayRef, ArrowError> {
  let list = array.as_string::<i64>();
  Ok(length_impl::<Int64Type>(list.offsets(), list.nulls()))
  }
+ DataType::Utf8View => {
+ let list = array.as_string_view();
+ let v = list.views().iter().map(|v| *v as i32).collect::<Vec<_>>();
+ Ok(Arc::new(PrimitiveArray::<Int32Type>::new(
+ v.into(),
+ list.nulls().cloned(),
+ )))
+ }
  DataType::Binary => {
  let list = array.as_binary::<i32>();
  Ok(length_impl::<Int32Type>(list.offsets(), list.nulls()))
@@ -147,9 +155,15 @@ mod tests {
 
  fn length_cases_string() -> Vec<(Vec<&'static str>, usize, Vec<i32>)> {
  // a large array
- let values = ["one", "on", "o", ""];
+ let values = [
+ "one",
+ "on",
+ "o",
+ "",
+ "this is a longer string to test string array with",
+ ];
  let values = values.into_iter().cycle().take(4096).collect();
- let expected = [3, 2, 1, 0].into_iter().cycle().take(4096).collect();
+ let expected = [3, 2, 1, 0, 49].into_iter().cycle().take(4096).collect();
 
  vec![
  (vec!["hello", " ", "world"], 3, vec![5, 1, 5]),
@@ -210,6 +224,21 @@ mod tests {
  })
  }
 
+ #[test]
+ fn length_test_string_view() {
+ length_cases_string()
+ .into_iter()
+ .for_each(|(input, len, expected)| {
+ let array = StringViewArray::from(input);
+ let result = length(&array).unwrap();
+ assert_eq!(len, result.len());
+ let result = result.as_any().downcast_ref::<Int32Array>().unwrap();
+ expected.iter().enumerate().for_each(|(i, value)| {
+ assert_eq!(*value, result.value(i));
+ });
+ })
+ }
+
  #[test]
  fn length_test_binary() {
  let value: Vec<&[u8]> = vec![b"zero", b"one", &[0xff, 0xf8]];