Move ListLikeArray to arrow-array to be shared with json writer and parquet unshredding

Author: liamzwbao

arrow-array/src/array/fixed_size_list_array.rs

@@ -530,6 +530,18 @@ unsafe impl Array for FixedSizeListArray {
     }
 }
 
+impl super::ListLikeArray for FixedSizeListArray {
+    fn values(&self) -> &ArrayRef {
+        self.values()
+    }
+
+    fn element_range(&self, index: usize) -> std::ops::Range<usize> {
+        let value_length = self.value_length().as_usize();
+        let offset = index * value_length;
+        offset..(offset + value_length)
+    }
+}
+
 impl ArrayAccessor for FixedSizeListArray {
     type Item = ArrayRef;
 

arrow-array/src/array/list_array.rs

@@ -622,6 +622,19 @@ unsafe impl<OffsetSize: OffsetSizeTrait> Array for GenericListArray<OffsetSize>
     }
 }
 
+impl<OffsetSize: OffsetSizeTrait> super::ListLikeArray for GenericListArray<OffsetSize> {
+    fn values(&self) -> &ArrayRef {
+        self.values()
+    }
+
+    fn element_range(&self, index: usize) -> std::ops::Range<usize> {
+        let offsets = self.offsets();
+        let start = offsets[index].as_usize();
+        let end = offsets[index + 1].as_usize();
+        start..end
+    }
+}
+
 impl<OffsetSize: OffsetSizeTrait> ArrayAccessor for &GenericListArray<OffsetSize> {
     type Item = ArrayRef;
 

arrow-array/src/array/list_view_array.rs

@@ -488,6 +488,18 @@ unsafe impl<OffsetSize: OffsetSizeTrait> Array for GenericListViewArray<OffsetSi
     }
 }
 
+impl<OffsetSize: OffsetSizeTrait> super::ListLikeArray for GenericListViewArray<OffsetSize> {
+    fn values(&self) -> &ArrayRef {
+        self.values()
+    }
+
+    fn element_range(&self, index: usize) -> std::ops::Range<usize> {
+        let offset = self.value_offsets()[index].as_usize();
+        let size = self.value_sizes()[index].as_usize();
+        offset..(offset + size)
+    }
+}
+
 impl<OffsetSize: OffsetSizeTrait> std::fmt::Debug for GenericListViewArray<OffsetSize> {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
         let prefix = OffsetSize::PREFIX;

arrow-array/src/array/mod.rs

@@ -667,6 +667,21 @@ impl<'a> BinaryArrayType<'a> for &'a FixedSizeBinaryArray {
     }
 }
 
+/// A trait for Arrow list-like arrays, abstracting over
+/// [`GenericListArray`], [`GenericListViewArray`], and [`FixedSizeListArray`].
+///
+/// This trait provides a uniform interface for accessing the child values and
+/// computing the element range for a given index, regardless of the underlying
+/// list layout (offsets, offsets+sizes, or fixed-size).
+pub trait ListLikeArray: Array {
+    /// Returns the child values array.
+    fn values(&self) -> &ArrayRef;
+
+    /// Returns the start and end indices into the values array for the list
+    /// element at `index`.
+    fn element_range(&self, index: usize) -> std::ops::Range<usize>;
+}
+
 impl PartialEq for dyn Array + '_ {
     fn eq(&self, other: &Self) -> bool {
         self.to_data().eq(&other.to_data())

parquet-variant-compute/src/arrow_to_variant.rs

@@ -16,8 +16,8 @@
 // under the License.
 
 use arrow::array::{
-    Array, ArrayRef, AsArray, FixedSizeListArray, GenericBinaryArray, GenericListArray,
-    GenericListViewArray, GenericStringArray, OffsetSizeTrait, PrimitiveArray,
+    Array, AsArray, FixedSizeListArray, GenericBinaryArray, GenericListArray, GenericListViewArray,
+    GenericStringArray, ListLikeArray, OffsetSizeTrait, PrimitiveArray,
 };
 use arrow::compute::{CastOptions, kernels::cast};
 use arrow::datatypes::{
@@ -32,7 +32,6 @@ use parquet_variant::{
     VariantDecimal16, VariantDecimalType,
 };
 use std::collections::HashMap;
-use std::ops::Range;
 
 // ============================================================================
 // Row-oriented builders for efficient Arrow-to-Variant conversion
@@ -552,54 +551,6 @@ impl<'a, L: ListLikeArray> ListArrowToVariantBuilder<'a, L> {
     }
 }
 
-/// Trait for list-like arrays that can provide element ranges
-pub(crate) trait ListLikeArray: Array {
-    /// Get the values array
-    fn values(&self) -> &ArrayRef;
-
-    /// Get the start and end indices for a list element
-    fn element_range(&self, index: usize) -> Range<usize>;
-}
-
-impl<O: OffsetSizeTrait> ListLikeArray for GenericListArray<O> {
-    fn values(&self) -> &ArrayRef {
-        self.values()
-    }
-
-    fn element_range(&self, index: usize) -> Range<usize> {
-        let offsets = self.offsets();
-        let start = offsets[index].as_usize();
-        let end = offsets[index + 1].as_usize();
-        start..end
-    }
-}
-
-impl<O: OffsetSizeTrait> ListLikeArray for GenericListViewArray<O> {
-    fn values(&self) -> &ArrayRef {
-        self.values()
-    }
-
-    fn element_range(&self, index: usize) -> Range<usize> {
-        let offsets = self.value_offsets();
-        let sizes = self.value_sizes();
-        let offset = offsets[index].as_usize();
-        let size = sizes[index].as_usize();
-        offset..(offset + size)
-    }
-}
-
-impl ListLikeArray for FixedSizeListArray {
-    fn values(&self) -> &ArrayRef {
-        self.values()
-    }
-
-    fn element_range(&self, index: usize) -> Range<usize> {
-        let value_length = self.value_length().as_usize();
-        let offset = index * value_length;
-        offset..(offset + value_length)
-    }
-}
-
 /// Struct builder for StructArray
 pub(crate) struct StructArrowToVariantBuilder<'a> {
     struct_array: &'a arrow::array::StructArray,

parquet-variant-compute/src/shred_variant.rs

@@ -652,10 +652,10 @@ impl VariantSchemaNode {
 mod tests {
     use super::*;
     use crate::VariantArrayBuilder;
-    use crate::arrow_to_variant::ListLikeArray;
     use arrow::array::{
         Array, BinaryViewArray, FixedSizeBinaryArray, Float64Array, GenericListArray,
-        GenericListViewArray, Int64Array, ListArray, OffsetSizeTrait, PrimitiveArray, StringArray,
+        GenericListViewArray, Int64Array, ListArray, ListLikeArray, OffsetSizeTrait,
+        PrimitiveArray, StringArray,
     };
     use arrow::datatypes::{
         ArrowPrimitiveType, DataType, Field, Fields, Int64Type, TimeUnit, UnionFields, UnionMode,

parquet-variant-compute/src/unshred_variant.rs

@@ -17,11 +17,11 @@
 
 //! Module for unshredding VariantArray by folding typed_value columns back into the value column.
 
-use crate::arrow_to_variant::ListLikeArray;
 use crate::{BorrowedShreddingState, VariantArray, VariantValueArrayBuilder};
 use arrow::array::{
     Array, AsArray as _, BinaryViewArray, BooleanArray, FixedSizeBinaryArray, FixedSizeListArray,
-    GenericListArray, GenericListViewArray, PrimitiveArray, StringArray, StructArray,
+    GenericListArray, GenericListViewArray, ListLikeArray, PrimitiveArray, StringArray,
+    StructArray,
 };
 use arrow::buffer::NullBuffer;
 use arrow::datatypes::{