fead: add GenericListViewArray::from_iter_primitive

arrow-array/src/array/list_view_array.rs

@@ -23,8 +23,12 @@ use std::ops::Add;
 use std::sync::Arc;
 
 use crate::array::{make_array, print_long_array};
+use crate::builder::{GenericListViewBuilder, PrimitiveBuilder};
 use crate::iterator::GenericListViewArrayIter;
-use crate::{Array, ArrayAccessor, ArrayRef, FixedSizeListArray, OffsetSizeTrait, new_empty_array};
+use crate::{
+    Array, ArrayAccessor, ArrayRef, ArrowPrimitiveType, FixedSizeListArray, OffsetSizeTrait,
+    new_empty_array,
+};
 
 /// A [`GenericListViewArray`] of variable size lists, storing offsets as `i32`.
 pub type ListViewArray = GenericListViewArray<i32>;
@@ -357,6 +361,46 @@ impl<OffsetSize: OffsetSizeTrait> GenericListViewArray<OffsetSize> {
             value_sizes: self.value_sizes.slice(offset, length),
         }
     }
+
+    /// Creates a [`GenericListViewArray`] from an iterator of primitive values
+    /// # Example
+    /// ```
+    /// # use arrow_array::ListViewArray;
+    /// # use arrow_array::types::Int32Type;
+    ///
+    /// 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 list_array = ListViewArray::from_iter_primitive::<Int32Type, _, _>(data);
+    /// println!("{:?}", list_array);
+    /// ```
+    pub fn from_iter_primitive<T, P, I>(iter: I) -> Self
+    where
+        T: ArrowPrimitiveType,
+        P: IntoIterator<Item = Option<<T as ArrowPrimitiveType>::Native>>,
+        I: IntoIterator<Item = Option<P>>,
+    {
+        let iter = iter.into_iter();
+        let size_hint = iter.size_hint().0;
+        let mut builder =
+            GenericListViewBuilder::with_capacity(PrimitiveBuilder::<T>::new(), size_hint);
+
+        for i in iter {
+            match i {
+                Some(p) => {
+                    for t in p {
+                        builder.values().append_option(t);
+                    }
+                    builder.append(true);
+                }
+                None => builder.append(false),
+            }
+        }
+        builder.finish()
+    }
 }
 
 impl<OffsetSize: OffsetSizeTrait> ArrayAccessor for &GenericListViewArray<OffsetSize> {
@@ -559,7 +603,7 @@ impl<OffsetSize: OffsetSizeTrait> GenericListViewArray<OffsetSize> {
 
 #[cfg(test)]
 mod tests {
-    use arrow_buffer::{BooleanBuffer, Buffer, ScalarBuffer, bit_util};
+    use arrow_buffer::{BooleanBuffer, Buffer, NullBufferBuilder, ScalarBuffer, bit_util};
     use arrow_schema::Field;
 
     use crate::builder::{FixedSizeListBuilder, Int32Builder};
@@ -1120,4 +1164,29 @@ mod tests {
             .collect();
         assert_eq!(values, vec![Some(vec![]), Some(vec![]), Some(vec![])]);
     }
+
+    #[test]
+    fn test_from_iter_primitive() {
+        let data = vec![
+            Some(vec![Some(0), Some(1), Some(2)]),
+            None,
+            Some(vec![Some(3), Some(4), Some(5)]),
+            Some(vec![Some(6), Some(7)]),
+        ];
+        let list_array = ListViewArray::from_iter_primitive::<Int32Type, _, _>(data);
+
+        //  [[0, 1, 2], NULL, [3, 4, 5], [6, 7]]
+        let values = Int32Array::from(vec![0, 1, 2, 3, 4, 5, 6, 7]);
+        let offsets = ScalarBuffer::from(vec![0, 3, 3, 6]);
+        let sizes = ScalarBuffer::from(vec![3, 0, 3, 2]);
+        let field = Arc::new(Field::new_list_field(DataType::Int32, true));
+
+        let mut nulls = NullBufferBuilder::new(4);
+        nulls.append(true);
+        nulls.append(false);
+        nulls.append_n_non_nulls(2);
+        let another = ListViewArray::new(field, offsets, sizes, Arc::new(values), nulls.finish());
+
+        assert_eq!(list_array, another)
+    }
 }