alamb commented on code in PR #6936:
URL: https://github.com/apache/arrow-datafusion/pull/6936#discussion_r1280565792
##########
datafusion/physical-expr/src/array_expressions.rs:
##########
@@ -363,6 +363,177 @@ pub fn make_array(arrays: &[ArrayRef]) ->
Result<ArrayRef> {
}
}
+fn return_empty(return_null: bool, data_type: DataType) -> Arc<dyn Array> {
+ if return_null {
+ new_null_array(&data_type, 1)
+ } else {
+ new_empty_array(&data_type)
+ }
+}
+
+macro_rules! list_slice {
+ ($ARRAY:expr, $I:expr, $J:expr, $RETURN_ELEMENT:expr, $ARRAY_TYPE:ident)
=> {{
+ let array = $ARRAY.as_any().downcast_ref::<$ARRAY_TYPE>().unwrap();
+ if $I == 0 && $J == 0 || $ARRAY.is_empty() {
+ return return_empty($RETURN_ELEMENT, $ARRAY.data_type().clone());
+ }
+
+ let i = if $I < 0 {
+ if $I.abs() as usize > array.len() {
+ return return_empty(true, $ARRAY.data_type().clone());
+ }
+
+ (array.len() as i64 + $I + 1) as usize
+ } else {
+ if $I == 0 {
+ 1
+ } else {
+ $I as usize
+ }
+ };
+ let j = if $J < 0 {
+ if $J.abs() as usize > array.len() {
+ return return_empty(true, $ARRAY.data_type().clone());
+ }
+
+ if $RETURN_ELEMENT {
+ (array.len() as i64 + $J + 1) as usize
+ } else {
+ (array.len() as i64 + $J) as usize
+ }
+ } else {
+ if $J == 0 {
+ 1
+ } else {
+ if $J as usize > array.len() {
+ array.len()
+ } else {
+ $J as usize
+ }
+ }
+ };
+
+ if i > j || i as usize > $ARRAY.len() {
+ return_empty($RETURN_ELEMENT, $ARRAY.data_type().clone())
+ } else {
+ Arc::new(array.slice((i - 1), (j + 1 - i)))
+ }
+ }};
+}
+
+macro_rules! slice {
Review Comment:
So in your example above, something more like
```rust
fn main() {
let list_array = todo!(); // define ListArray here
let data = vec![
Some(vec![Some(0), Some(1), Some(2)]),
None,
Some(vec![Some(3), None, Some(5)]),
Some(vec![Some(6), Some(7)]),
];
let indices = UInt32::from_iter_primitive::<Int32Type, _, _>(data);
let taken = take(&list_array.values(), &indices, None).unwrap();
```
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