Merge pull request #5 from relativityone/fix-list-offsets

fix: Encoding of List offsets was incorrect when slice offsets begin with zero

arrow-ipc/src/writer.rs

@@ -1309,7 +1309,7 @@ fn reencode_offsets<O: OffsetSizeTrait>(
     let end_offset = offset_slice.last().unwrap();
 
     let offsets = match start_offset.as_usize() {
-        0 => offsets.clone(),
+        0 => offset_slice.iter().copied().collect(),
         _ => offset_slice.iter().map(|x| *x - *start_offset).collect(),
     };
 
@@ -2396,6 +2396,38 @@ mod tests {
         ls.finish()
     }
 
+    fn generate_nested_list_data_starting_at_zero<O: OffsetSizeTrait>() -> GenericListArray<O> {
+        let mut ls =
+            GenericListBuilder::<O, _>::new(GenericListBuilder::<O, _>::new(UInt32Builder::new()));
+
+
+        for _i in 0..999 {
+            ls.values().append(true);
+            ls.append(true);
+        }
+
+        for j in 0..10 {
+            for value in [j, j, j, j] {
+                ls.values().values().append_value(value);
+            }
+            ls.values().append(true)
+        }
+        ls.append(true);
+
+
+        for i in 0..9_000 {
+            for j in 0..10 {
+                for value in [i+j, i+j, i+j, i+j] {
+                    ls.values().values().append_value(value);
+                }
+                ls.values().append(true)
+            }
+            ls.append(true);
+        }
+
+        ls.finish()
+    }
+
     fn generate_map_array_data() -> MapArray {
         let keys_builder = UInt32Builder::new();
         let values_builder = UInt32Builder::new();
@@ -2487,6 +2519,19 @@ mod tests {
         roundtrip_ensure_sliced_smaller(in_batch, 1000);
     }
 
+    #[test]
+    fn encode_nested_lists_starting_at_zero() {
+        let inner_int = Arc::new(Field::new("item", DataType::UInt32, true));
+        let inner_list_field = Arc::new(Field::new("item", DataType::List(inner_int), true));
+        let list_field = Field::new("val", DataType::List(inner_list_field), true);
+        let schema = Arc::new(Schema::new(vec![list_field]));
+
+        let values = Arc::new(generate_nested_list_data_starting_at_zero::<i32>());
+
+        let in_batch = RecordBatch::try_new(schema, vec![values]).unwrap();
+        roundtrip_ensure_sliced_smaller(in_batch, 1000);
+    }
+
     #[test]
     fn encode_map_array() {
         let keys = Arc::new(Field::new("keys", DataType::UInt32, false));