Dandandan commented on code in PR #9971:
URL: https://github.com/apache/arrow-datafusion/pull/9971#discussion_r1559142821
##########
datafusion/functions/src/string/common.rs:
##########
@@ -97,80 +101,145 @@ pub(crate) fn general_trim<T: OffsetSizeTrait>(
}
}
-/// applies a unary expression to `args[0]` that is expected to be
downcastable to
-/// a `GenericStringArray` and returns a `GenericStringArray` (which may have
a different offset)
-/// # Errors
-/// This function errors when:
-/// * the number of arguments is not 1
-/// * the first argument is not castable to a `GenericStringArray`
-pub(crate) fn unary_string_function<'a, T, O, F, R>(
- args: &[&'a dyn Array],
- op: F,
- name: &str,
-) -> Result<GenericStringArray<O>>
-where
- R: AsRef<str>,
- O: OffsetSizeTrait,
- T: OffsetSizeTrait,
- F: Fn(&'a str) -> R,
-{
- if args.len() != 1 {
- return exec_err!(
- "{:?} args were supplied but {} takes exactly one argument",
- args.len(),
- name
- );
- }
-
- let string_array = as_generic_string_array::<T>(args[0])?;
+pub(crate) fn to_lower(args: &[ColumnarValue], name: &str) ->
Result<ColumnarValue> {
+ case_conversion(args, |string| string.to_lowercase(), name)
+}
- // first map is the iterator, second is for the `Option<_>`
- Ok(string_array.iter().map(|string| string.map(&op)).collect())
+pub(crate) fn to_upper(args: &[ColumnarValue], name: &str) ->
Result<ColumnarValue> {
+ case_conversion(args, |string| string.to_uppercase(), name)
}
-pub(crate) fn handle<'a, F, R>(
+fn case_conversion<'a, F>(
args: &'a [ColumnarValue],
op: F,
name: &str,
) -> Result<ColumnarValue>
where
- R: AsRef<str>,
- F: Fn(&'a str) -> R,
+ F: Fn(&'a str) -> String,
{
match &args[0] {
- ColumnarValue::Array(a) => match a.data_type() {
- DataType::Utf8 => {
- Ok(ColumnarValue::Array(Arc::new(unary_string_function::<
- i32,
- i32,
- _,
- _,
- >(
- &[a.as_ref()], op, name
- )?)))
- }
- DataType::LargeUtf8 => {
- Ok(ColumnarValue::Array(Arc::new(unary_string_function::<
- i64,
- i64,
- _,
- _,
- >(
- &[a.as_ref()], op, name
- )?)))
- }
+ ColumnarValue::Array(array) => match array.data_type() {
+ DataType::Utf8 =>
Ok(ColumnarValue::Array(case_conversion_array::<i32, _>(
+ array, op,
+ )?)),
+ DataType::LargeUtf8 =>
Ok(ColumnarValue::Array(case_conversion_array::<
+ i64,
+ _,
+ >(array, op)?)),
other => exec_err!("Unsupported data type {other:?} for function
{name}"),
},
ColumnarValue::Scalar(scalar) => match scalar {
ScalarValue::Utf8(a) => {
- let result = a.as_ref().map(|x| (op)(x).as_ref().to_string());
+ let result = a.as_ref().map(|x| op(x));
Ok(ColumnarValue::Scalar(ScalarValue::Utf8(result)))
}
ScalarValue::LargeUtf8(a) => {
- let result = a.as_ref().map(|x| (op)(x).as_ref().to_string());
+ let result = a.as_ref().map(|x| op(x));
Ok(ColumnarValue::Scalar(ScalarValue::LargeUtf8(result)))
}
other => exec_err!("Unsupported data type {other:?} for function
{name}"),
},
}
}
+
+fn case_conversion_array<'a, O, F>(array: &'a ArrayRef, op: F) ->
Result<ArrayRef>
+where
+ O: OffsetSizeTrait,
+ F: Fn(&'a str) -> String,
+{
+ let string_array = as_generic_string_array::<O>(array)?;
+ let item_len = string_array.len();
+
+ // Find the first nonascii string at the beginning.
+ let find_the_first_nonascii = || {
Review Comment:
AFAIK it is quite a bit faster to do the check once on the entire
string/byte array (including nulls), than to check it individually.
This should simplify the logic as well, e.g. not searching for the index but
only do it when the entire array is ascii.
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