From 412631b6705257f571518a4bb2133a5a4d9cb7d3 Mon Sep 17 00:00:00 2001
From: Matthijs Brobbel <m1brobbel@gmail.com>
Date: Thu, 5 Sep 2024 16:03:33 +0200
Subject: [PATCH 1/2] feat!: make `StructArray` generic over child array
 `OffsetElement` and `UnionType`

---
 narrow-derive/src/struct.rs |   2 +-
 src/array/struct.rs         | 178 +++++++++++++++++++++++++-----------
 src/arrow/array/struct.rs   | 116 ++++++++++++++---------
 3 files changed, 202 insertions(+), 94 deletions(-)

diff --git a/narrow-derive/src/struct.rs b/narrow-derive/src/struct.rs
index aa55de1..3340435 100644
--- a/narrow-derive/src/struct.rs
+++ b/narrow-derive/src/struct.rs
@@ -246,7 +246,7 @@ impl Struct<'_> {
         let array_struct_ident = self.array_struct_ident();
         let tokens = quote! {
             impl #impl_generics #narrow::array::StructArrayType for #ident #ty_generics #where_clause {
-                type Array<Buffer: #narrow::buffer::BufferType> = #array_struct_ident #array_ty_generics;
+                type Array<Buffer: #narrow::buffer::BufferType, OffsetItem: #narrow::offset::OffsetElement, UnionLayout: #narrow::array::r#union::UnionType> = #array_struct_ident #array_ty_generics;
             }
         };
         parse2(tokens).expect("struct_array_type_impl")
diff --git a/src/array/struct.rs b/src/array/struct.rs
index af03cb7..5f0cd5c 100644
--- a/src/array/struct.rs
+++ b/src/array/struct.rs
@@ -1,10 +1,11 @@
 //! Array for product types.
 
-use super::{Array, ArrayType};
+use super::{union, Array, ArrayType, UnionType};
 use crate::{
     bitmap::{Bitmap, BitmapRef, BitmapRefMut, ValidityBitmap},
     buffer::{BufferType, VecBuffer},
     nullable::Nullable,
+    offset::{self, OffsetElement},
     validity::{Nullability, Validity},
     Length,
 };
@@ -15,7 +16,7 @@ pub trait StructArrayType: ArrayType<Self> {
     /// the [`ArrayType`] array because that wraps this array. Also note that this
     /// has no [`Array`] bound.
     // TODO(mbrobbe): add offset and union generics
-    type Array<Buffer: BufferType>; // into<fields> this then requires all arraytype impls to provide a field
+    type Array<Buffer: BufferType, OffsetItem: OffsetElement, UnionLayout: UnionType>; // into<fields> this then requires all arraytype impls to provide a field
 }
 
 /// Array for product types.
@@ -23,13 +24,21 @@ pub struct StructArray<
     T: StructArrayType,
     const NULLABLE: bool = false,
     Buffer: BufferType = VecBuffer,
->(pub <<T as StructArrayType>::Array<Buffer> as Validity<NULLABLE>>::Storage<Buffer>)
+    OffsetItem: OffsetElement = offset::NA,
+    UnionLayout: UnionType = union::NA,
+>(pub <<T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout> as Validity<NULLABLE>>::Storage<Buffer>)
 where
-    <T as StructArrayType>::Array<Buffer>: Validity<NULLABLE>;
-
-impl<T: StructArrayType, const NULLABLE: bool, Buffer: BufferType> StructArray<T, NULLABLE, Buffer>
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>: Validity<NULLABLE>;
+
+impl<
+        T: StructArrayType,
+        const NULLABLE: bool,
+        Buffer: BufferType,
+        OffsetItem: OffsetElement,
+        UnionLayout: UnionType,
+    > StructArray<T, NULLABLE, Buffer, OffsetItem, UnionLayout>
 where
-    <T as StructArrayType>::Array<Buffer>: Validity<NULLABLE>,
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>: Validity<NULLABLE>,
     for<'a> &'a Self: IntoIterator,
 {
     /// Returns an iterator over the items in this [`StructArray`].
@@ -38,105 +47,155 @@ where
     }
 }
 
-impl<T: StructArrayType, const NULLABLE: bool, Buffer: BufferType> Array
-    for StructArray<T, NULLABLE, Buffer>
+impl<
+        T: StructArrayType,
+        const NULLABLE: bool,
+        Buffer: BufferType,
+        OffsetItem: OffsetElement,
+        UnionLayout: UnionType,
+    > Array for StructArray<T, NULLABLE, Buffer, OffsetItem, UnionLayout>
 where
-    <T as StructArrayType>::Array<Buffer>: Validity<NULLABLE>,
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>: Validity<NULLABLE>,
     T: Nullability<NULLABLE>,
 {
     type Item = <T as Nullability<NULLABLE>>::Item;
 }
 
-impl<T: StructArrayType, const NULLABLE: bool, Buffer: BufferType> Clone
-    for StructArray<T, NULLABLE, Buffer>
+impl<
+        T: StructArrayType,
+        const NULLABLE: bool,
+        Buffer: BufferType,
+        OffsetItem: OffsetElement,
+        UnionLayout: UnionType,
+    > Clone for StructArray<T, NULLABLE, Buffer, OffsetItem, UnionLayout>
 where
-    <T as StructArrayType>::Array<Buffer>: Validity<NULLABLE>,
-    <<T as StructArrayType>::Array<Buffer> as Validity<NULLABLE>>::Storage<Buffer>: Clone,
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>: Validity<NULLABLE>,
+    <<T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout> as Validity<NULLABLE>>::Storage<
+        Buffer,
+    >: Clone,
 {
     fn clone(&self) -> Self {
         Self(self.0.clone())
     }
 }
 
-impl<T: StructArrayType, const NULLABLE: bool, Buffer: BufferType> Default
-    for StructArray<T, NULLABLE, Buffer>
+impl<
+        T: StructArrayType,
+        const NULLABLE: bool,
+        Buffer: BufferType,
+        OffsetItem: OffsetElement,
+        UnionLayout: UnionType,
+    > Default for StructArray<T, NULLABLE, Buffer, OffsetItem, UnionLayout>
 where
-    <T as StructArrayType>::Array<Buffer>: Validity<NULLABLE>,
-    <<T as StructArrayType>::Array<Buffer> as Validity<NULLABLE>>::Storage<Buffer>: Default,
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>: Validity<NULLABLE>,
+    <<T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout> as Validity<NULLABLE>>::Storage<
+        Buffer,
+    >: Default,
 {
     fn default() -> Self {
         Self(Default::default())
     }
 }
 
-impl<T: StructArrayType, Buffer: BufferType> From<StructArray<T, false, Buffer>>
-    for StructArray<T, true, Buffer>
+impl<T: StructArrayType, Buffer: BufferType, OffsetItem: OffsetElement, UnionLayout: UnionType>
+    From<StructArray<T, false, Buffer, OffsetItem, UnionLayout>>
+    for StructArray<T, true, Buffer, OffsetItem, UnionLayout>
 where
-    <T as StructArrayType>::Array<Buffer>: Length,
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>: Length,
     Bitmap<Buffer>: FromIterator<bool>,
 {
-    fn from(value: StructArray<T, false, Buffer>) -> Self {
+    fn from(value: StructArray<T, false, Buffer, OffsetItem, UnionLayout>) -> Self {
         Self(Nullable::from(value.0))
     }
 }
 
-impl<T: StructArrayType, U, const NULLABLE: bool, Buffer: BufferType> FromIterator<U>
-    for StructArray<T, NULLABLE, Buffer>
+impl<
+        T: StructArrayType,
+        U,
+        const NULLABLE: bool,
+        Buffer: BufferType,
+        OffsetItem: OffsetElement,
+        UnionLayout: UnionType,
+    > FromIterator<U> for StructArray<T, NULLABLE, Buffer, OffsetItem, UnionLayout>
 where
-    <T as StructArrayType>::Array<Buffer>: Validity<NULLABLE>,
-    <<T as StructArrayType>::Array<Buffer> as Validity<NULLABLE>>::Storage<Buffer>: FromIterator<U>,
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>: Validity<NULLABLE>,
+    <<T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout> as Validity<NULLABLE>>::Storage<
+        Buffer,
+    >: FromIterator<U>,
 {
     fn from_iter<I: IntoIterator<Item = U>>(iter: I) -> Self {
         Self(iter.into_iter().collect())
     }
 }
 
-impl<T: StructArrayType, U, Buffer: BufferType> Extend<U> for StructArray<T, false, Buffer>
+impl<
+        T: StructArrayType,
+        U,
+        Buffer: BufferType,
+        OffsetItem: OffsetElement,
+        UnionLayout: UnionType,
+    > Extend<U> for StructArray<T, false, Buffer, OffsetItem, UnionLayout>
 where
-    <T as StructArrayType>::Array<Buffer>: Extend<U>,
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>: Extend<U>,
 {
     fn extend<I: IntoIterator<Item = U>>(&mut self, iter: I) {
         self.0.extend(iter);
     }
 }
 
-impl<T: StructArrayType, U, Buffer: BufferType> Extend<Option<U>> for StructArray<T, true, Buffer>
+impl<
+        T: StructArrayType,
+        U,
+        Buffer: BufferType,
+        OffsetItem: OffsetElement,
+        UnionLayout: UnionType,
+    > Extend<Option<U>> for StructArray<T, true, Buffer, OffsetItem, UnionLayout>
 where
-    Nullable<<T as StructArrayType>::Array<Buffer>, Buffer>: Extend<Option<U>>,
+    Nullable<<T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>, Buffer>:
+        Extend<Option<U>>,
 {
     fn extend<I: IntoIterator<Item = Option<U>>>(&mut self, iter: I) {
         self.0.extend(iter);
     }
 }
 
-impl<T: StructArrayType, const NULLABLE: bool, Buffer: BufferType> IntoIterator
-    for StructArray<T, NULLABLE, Buffer>
+impl<
+        T: StructArrayType,
+        const NULLABLE: bool,
+        Buffer: BufferType,
+        OffsetItem: OffsetElement,
+        UnionLayout: UnionType,
+    > IntoIterator for StructArray<T, NULLABLE, Buffer, OffsetItem, UnionLayout>
 where
     T: Nullability<NULLABLE>,
-    <T as StructArrayType>::Array<Buffer>: Validity<NULLABLE>,
-    <<T as StructArrayType>::Array<Buffer> as Validity<NULLABLE>>::Storage<Buffer>: IntoIterator,
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>: Validity<NULLABLE>,
+    <<T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout> as Validity<NULLABLE>>::Storage<
+        Buffer,
+    >: IntoIterator,
 {
-    type Item = <<<T as StructArrayType>::Array<Buffer> as Validity<NULLABLE>>::Storage<Buffer> as
-        IntoIterator>::Item;
-    type IntoIter = <<<T as StructArrayType>::Array<Buffer> as Validity<NULLABLE>>::Storage<Buffer> as
-        IntoIterator>::IntoIter;
+    type Item = <<<T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout> as Validity<
+        NULLABLE,
+    >>::Storage<Buffer> as IntoIterator>::Item;
+    type IntoIter = <<<T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout> as Validity<
+        NULLABLE,
+    >>::Storage<Buffer> as IntoIterator>::IntoIter;
 
     fn into_iter(self) -> Self::IntoIter {
         self.0.into_iter()
     }
 }
 
-impl<'a, T: StructArrayType, const NULLABLE: bool, Buffer: BufferType> IntoIterator
-    for &'a StructArray<T, NULLABLE, Buffer>
+impl<'a, T: StructArrayType, const NULLABLE: bool, Buffer: BufferType, OffsetItem: OffsetElement, UnionLayout: UnionType> IntoIterator
+    for &'a StructArray<T, NULLABLE, Buffer, OffsetItem, UnionLayout>
 where
     T: Nullability<NULLABLE>,
-    <T as StructArrayType>::Array<Buffer>: Validity<NULLABLE>,
-    &'a <<T as StructArrayType>::Array<Buffer> as Validity<NULLABLE>>::Storage<Buffer>:
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>: Validity<NULLABLE>,
+    &'a <<T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout> as Validity<NULLABLE>>::Storage<Buffer>:
         IntoIterator,
 {
-    type Item = <&'a <<T as StructArrayType>::Array<Buffer> as Validity<NULLABLE>>::Storage<Buffer> as
+    type Item = <&'a <<T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout> as Validity<NULLABLE>>::Storage<Buffer> as
         IntoIterator>::Item;
-    type IntoIter = <&'a <<T as StructArrayType>::Array<Buffer> as Validity<NULLABLE>>::Storage<
+    type IntoIter = <&'a <<T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout> as Validity<NULLABLE>>::Storage<
         Buffer,
     > as IntoIterator>::IntoIter;
 
@@ -145,18 +204,27 @@ where
     }
 }
 
-impl<T: StructArrayType, const NULLABLE: bool, Buffer: BufferType> Length
-    for StructArray<T, NULLABLE, Buffer>
+impl<
+        T: StructArrayType,
+        const NULLABLE: bool,
+        Buffer: BufferType,
+        OffsetItem: OffsetElement,
+        UnionLayout: UnionType,
+    > Length for StructArray<T, NULLABLE, Buffer, OffsetItem, UnionLayout>
 where
-    <T as StructArrayType>::Array<Buffer>: Validity<NULLABLE>,
-    <<T as StructArrayType>::Array<Buffer> as Validity<NULLABLE>>::Storage<Buffer>: Length,
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>: Validity<NULLABLE>,
+    <<T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout> as Validity<NULLABLE>>::Storage<
+        Buffer,
+    >: Length,
 {
     fn len(&self) -> usize {
         self.0.len()
     }
 }
 
-impl<T: StructArrayType, Buffer: BufferType> BitmapRef for StructArray<T, true, Buffer> {
+impl<T: StructArrayType, Buffer: BufferType, OffsetItem: OffsetElement, UnionLayout: UnionType>
+    BitmapRef for StructArray<T, true, Buffer, OffsetItem, UnionLayout>
+{
     type Buffer = Buffer;
 
     fn bitmap_ref(&self) -> &Bitmap<Self::Buffer> {
@@ -164,13 +232,18 @@ impl<T: StructArrayType, Buffer: BufferType> BitmapRef for StructArray<T, true,
     }
 }
 
-impl<T: StructArrayType, Buffer: BufferType> BitmapRefMut for StructArray<T, true, Buffer> {
+impl<T: StructArrayType, Buffer: BufferType, OffsetItem: OffsetElement, UnionLayout: UnionType>
+    BitmapRefMut for StructArray<T, true, Buffer, OffsetItem, UnionLayout>
+{
     fn bitmap_ref_mut(&mut self) -> &mut Bitmap<Self::Buffer> {
         self.0.bitmap_ref_mut()
     }
 }
 
-impl<T: StructArrayType, Buffer: BufferType> ValidityBitmap for StructArray<T, true, Buffer> {}
+impl<T: StructArrayType, Buffer: BufferType, OffsetItem: OffsetElement, UnionLayout: UnionType>
+    ValidityBitmap for StructArray<T, true, Buffer, OffsetItem, UnionLayout>
+{
+}
 
 #[cfg(test)]
 mod tests {
@@ -312,7 +385,8 @@ mod tests {
         }
     }
     impl<'a> StructArrayType for Foo<'a> {
-        type Array<Buffer: BufferType> = FooArray<'a, Buffer>;
+        type Array<Buffer: BufferType, OffsetItem: OffsetElement, UnionLayout: UnionType> =
+            FooArray<'a, Buffer>;
     }
 
     impl<'a, Buffer: BufferType> Length for FooArray<'a, Buffer>
diff --git a/src/arrow/array/struct.rs b/src/arrow/array/struct.rs
index e2da246..cab81d2 100644
--- a/src/arrow/array/struct.rs
+++ b/src/arrow/array/struct.rs
@@ -6,10 +6,11 @@ use arrow_buffer::NullBuffer;
 use arrow_schema::{DataType, Field, Fields};
 
 use crate::{
-    array::{StructArray, StructArrayType},
+    array::{StructArray, StructArrayType, UnionType},
     bitmap::Bitmap,
     buffer::BufferType,
     nullable::Nullable,
+    offset::OffsetElement,
     validity::{Nullability, Validity},
     Length,
 };
@@ -20,10 +21,16 @@ pub trait StructArrayTypeFields {
     fn fields() -> Fields;
 }
 
-impl<T: StructArrayType, const NULLABLE: bool, Buffer: BufferType> crate::arrow::Array
-    for StructArray<T, NULLABLE, Buffer>
+impl<
+        T: StructArrayType,
+        const NULLABLE: bool,
+        Buffer: BufferType,
+        OffsetItem: OffsetElement,
+        UnionLayout: UnionType,
+    > crate::arrow::Array for StructArray<T, NULLABLE, Buffer, OffsetItem, UnionLayout>
 where
-    <T as StructArrayType>::Array<Buffer>: Validity<NULLABLE> + StructArrayTypeFields,
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>:
+        Validity<NULLABLE> + StructArrayTypeFields,
     T: Nullability<NULLABLE>,
 {
     type Array = arrow_array::StructArray;
@@ -31,18 +38,26 @@ where
     fn as_field(name: &str) -> arrow_schema::Field {
         Field::new(
             name,
-            DataType::Struct(
-                <<T as StructArrayType>::Array<Buffer> as StructArrayTypeFields>::fields(),
-            ),
+            DataType::Struct(<<T as StructArrayType>::Array<
+                Buffer,
+                OffsetItem,
+                UnionLayout,
+            > as StructArrayTypeFields>::fields()),
             NULLABLE,
         )
     }
 }
 
-impl<T: StructArrayType, const NULLABLE: bool, Buffer: BufferType> From<Arc<dyn arrow_array::Array>>
-    for StructArray<T, NULLABLE, Buffer>
+impl<
+        T: StructArrayType,
+        const NULLABLE: bool,
+        Buffer: BufferType,
+        OffsetItem: OffsetElement,
+        UnionLayout: UnionType,
+    > From<Arc<dyn arrow_array::Array>>
+    for StructArray<T, NULLABLE, Buffer, OffsetItem, UnionLayout>
 where
-    <T as StructArrayType>::Array<Buffer>: Validity<NULLABLE>,
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>: Validity<NULLABLE>,
     Self: From<arrow_array::StructArray>,
 {
     fn from(value: Arc<dyn arrow_array::Array>) -> Self {
@@ -50,29 +65,35 @@ where
     }
 }
 
-impl<T: StructArrayType, const NULLABLE: bool, Buffer: BufferType>
-    From<StructArray<T, NULLABLE, Buffer>> for Arc<dyn arrow_array::Array>
+impl<
+        T: StructArrayType,
+        const NULLABLE: bool,
+        Buffer: BufferType,
+        OffsetItem: OffsetElement,
+        UnionLayout: UnionType,
+    > From<StructArray<T, NULLABLE, Buffer, OffsetItem, UnionLayout>>
+    for Arc<dyn arrow_array::Array>
 where
-    <T as StructArrayType>::Array<Buffer>: Validity<NULLABLE>,
-    arrow_array::StructArray: From<StructArray<T, NULLABLE, Buffer>>,
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>: Validity<NULLABLE>,
+    arrow_array::StructArray: From<StructArray<T, NULLABLE, Buffer, OffsetItem, UnionLayout>>,
 {
-    fn from(value: StructArray<T, NULLABLE, Buffer>) -> Self {
+    fn from(value: StructArray<T, NULLABLE, Buffer, OffsetItem, UnionLayout>) -> Self {
         Arc::new(arrow_array::StructArray::from(value))
     }
 }
 
-impl<T: StructArrayType, Buffer: BufferType> From<StructArray<T, false, Buffer>>
-    for arrow_array::StructArray
+impl<T: StructArrayType, Buffer: BufferType, OffsetItem: OffsetElement, UnionLayout: UnionType>
+    From<StructArray<T, false, Buffer, OffsetItem, UnionLayout>> for arrow_array::StructArray
 where
-    <T as StructArrayType>::Array<Buffer>:
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>:
         StructArrayTypeFields + Into<Vec<Arc<dyn arrow_array::Array>>>,
 {
-    fn from(value: StructArray<T, false, Buffer>) -> Self {
+    fn from(value: StructArray<T, false, Buffer, OffsetItem, UnionLayout>) -> Self {
         // Safety:
         // - struct arrays are valid by construction
         unsafe {
             arrow_array::StructArray::new_unchecked(
-                <<T as StructArrayType>::Array<Buffer> as StructArrayTypeFields>::fields(),
+                <<T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout> as StructArrayTypeFields>::fields(),
                 value.0.into(),
                 None,
             )
@@ -80,19 +101,19 @@ where
     }
 }
 
-impl<T: StructArrayType, Buffer: BufferType> From<StructArray<T, true, Buffer>>
-    for arrow_array::StructArray
+impl<T: StructArrayType, Buffer: BufferType, OffsetItem: OffsetElement, UnionLayout: UnionType>
+    From<StructArray<T, true, Buffer, OffsetItem, UnionLayout>> for arrow_array::StructArray
 where
-    <T as StructArrayType>::Array<Buffer>:
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>:
         StructArrayTypeFields + Into<Vec<Arc<dyn arrow_array::Array>>>,
     Bitmap<Buffer>: Into<NullBuffer>,
 {
-    fn from(value: StructArray<T, true, Buffer>) -> Self {
+    fn from(value: StructArray<T, true, Buffer, OffsetItem, UnionLayout>) -> Self {
         // Safety:
         // - struct arrays are valid by construction
         unsafe {
             arrow_array::StructArray::new_unchecked(
-                <<T as StructArrayType>::Array<Buffer> as StructArrayTypeFields>::fields(),
+                <<T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout> as StructArrayTypeFields>::fields(),
                 value.0.data.into(),
                 Some(value.0.validity.into()),
             )
@@ -101,10 +122,11 @@ where
 }
 
 /// Panics when there are nulls
-impl<T: StructArrayType, Buffer: BufferType> From<arrow_array::StructArray>
-    for StructArray<T, false, Buffer>
+impl<T: StructArrayType, Buffer: BufferType, OffsetItem: OffsetElement, UnionLayout: UnionType>
+    From<arrow_array::StructArray> for StructArray<T, false, Buffer, OffsetItem, UnionLayout>
 where
-    <T as StructArrayType>::Array<Buffer>: From<Vec<Arc<dyn arrow_array::Array>>>,
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>:
+        From<Vec<Arc<dyn arrow_array::Array>>>,
 {
     fn from(value: arrow_array::StructArray) -> Self {
         let (_fields, arrays, nulls_opt) = value.into_parts();
@@ -115,10 +137,11 @@ where
     }
 }
 
-impl<T: StructArrayType, Buffer: BufferType> From<arrow_array::StructArray>
-    for StructArray<T, true, Buffer>
+impl<T: StructArrayType, Buffer: BufferType, OffsetItem: OffsetElement, UnionLayout: UnionType>
+    From<arrow_array::StructArray> for StructArray<T, true, Buffer, OffsetItem, UnionLayout>
 where
-    <T as StructArrayType>::Array<Buffer>: From<Vec<Arc<dyn arrow_array::Array>>> + Length,
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>:
+        From<Vec<Arc<dyn arrow_array::Array>>> + Length,
     Bitmap<Buffer>: From<NullBuffer> + FromIterator<bool>,
 {
     fn from(value: arrow_array::StructArray) -> Self {
@@ -129,26 +152,36 @@ where
                 data,
                 validity: null_buffer.into(),
             }),
-            None => StructArray::<T, false, Buffer>(data).into(),
+            None => StructArray::<T, false, Buffer, OffsetItem, UnionLayout>(data).into(),
         }
     }
 }
 
-impl<T: StructArrayType, const NULLABLE: bool, Buffer: BufferType>
-    From<StructArray<T, NULLABLE, Buffer>> for arrow_array::RecordBatch
+impl<
+        T: StructArrayType,
+        const NULLABLE: bool,
+        Buffer: BufferType,
+        OffsetItem: OffsetElement,
+        UnionLayout: UnionType,
+    > From<StructArray<T, NULLABLE, Buffer, OffsetItem, UnionLayout>> for arrow_array::RecordBatch
 where
-    <T as StructArrayType>::Array<Buffer>: Validity<NULLABLE>,
-    arrow_array::StructArray: From<StructArray<T, NULLABLE, Buffer>>,
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>: Validity<NULLABLE>,
+    arrow_array::StructArray: From<StructArray<T, NULLABLE, Buffer, OffsetItem, UnionLayout>>,
 {
-    fn from(value: StructArray<T, NULLABLE, Buffer>) -> Self {
+    fn from(value: StructArray<T, NULLABLE, Buffer, OffsetItem, UnionLayout>) -> Self {
         Self::from(arrow_array::StructArray::from(value))
     }
 }
 
-impl<T: StructArrayType, const NULLABLE: bool, Buffer: BufferType> From<arrow_array::RecordBatch>
-    for StructArray<T, NULLABLE, Buffer>
+impl<
+        T: StructArrayType,
+        const NULLABLE: bool,
+        Buffer: BufferType,
+        OffsetItem: OffsetElement,
+        UnionLayout: UnionType,
+    > From<arrow_array::RecordBatch> for StructArray<T, NULLABLE, Buffer, OffsetItem, UnionLayout>
 where
-    <T as StructArrayType>::Array<Buffer>: Validity<NULLABLE>,
+    <T as StructArrayType>::Array<Buffer, OffsetItem, UnionLayout>: Validity<NULLABLE>,
     Self: From<arrow_array::StructArray>,
 {
     fn from(value: arrow_array::RecordBatch) -> Self {
@@ -250,7 +283,8 @@ mod tests {
         }
     }
     impl StructArrayType for Foo {
-        type Array<Buffer: BufferType> = FooArray<Buffer>;
+        type Array<Buffer: BufferType, OffsetItem: OffsetElement, UnionLayout: UnionType> =
+            FooArray<Buffer>;
     }
     impl<Buffer: BufferType> StructArrayTypeFields for FooArray<Buffer> {
         fn fields() -> Fields {

From 61b400feaf482a1c88222adbc3fded77eeec9a86 Mon Sep 17 00:00:00 2001
From: Matthijs Brobbel <m1brobbel@gmail.com>
Date: Thu, 5 Sep 2024 16:06:04 +0200
Subject: [PATCH 2/2] Update macrotest output

---
 .../expand/struct/named/generic.expanded.rs    |  6 +++++-
 .../struct/named/generic_option.expanded.rs    |  6 +++++-
 .../expand/struct/named/simple.expanded.rs     |  6 +++++-
 .../struct/unit/const_generic.expanded.rs      |  6 +++++-
 .../unit/const_generic_default.expanded.rs     |  6 +++++-
 .../tests/expand/struct/unit/self.expanded.rs  |  6 +++++-
 .../expand/struct/unit/simple.expanded.rs      |  6 +++++-
 .../struct/unit/where_clause.expanded.rs       |  6 +++++-
 .../expand/struct/unnamed/generic.expanded.rs  | 12 ++++++++++--
 .../expand/struct/unnamed/lifetime.expanded.rs |  6 +++++-
 .../expand/struct/unnamed/multiple.expanded.rs |  6 +++++-
 .../expand/struct/unnamed/nested.expanded.rs   | 12 ++++++++++--
 .../struct/unnamed/nested_generic.expanded.rs  | 18 +++++++++++++++---
 .../expand/struct/unnamed/simple.expanded.rs   |  6 +++++-
 14 files changed, 90 insertions(+), 18 deletions(-)

diff --git a/narrow-derive/tests/expand/struct/named/generic.expanded.rs b/narrow-derive/tests/expand/struct/named/generic.expanded.rs
index d90b08b..285b7d0 100644
--- a/narrow-derive/tests/expand/struct/named/generic.expanded.rs
+++ b/narrow-derive/tests/expand/struct/named/generic.expanded.rs
@@ -30,7 +30,11 @@ impl<'a, T: narrow::array::ArrayType<T>> narrow::array::StructArrayType for Foo<
 where
     T: Copy,
 {
-    type Array<Buffer: narrow::buffer::BufferType> = FooArray<'a, T, Buffer>;
+    type Array<
+        Buffer: narrow::buffer::BufferType,
+        OffsetItem: narrow::offset::OffsetElement,
+        UnionLayout: narrow::array::union::UnionType,
+    > = FooArray<'a, T, Buffer>;
 }
 struct FooArray<'a, T: narrow::array::ArrayType<T>, Buffer: narrow::buffer::BufferType>
 where
diff --git a/narrow-derive/tests/expand/struct/named/generic_option.expanded.rs b/narrow-derive/tests/expand/struct/named/generic_option.expanded.rs
index 6a869d5..deb9cb0 100644
--- a/narrow-derive/tests/expand/struct/named/generic_option.expanded.rs
+++ b/narrow-derive/tests/expand/struct/named/generic_option.expanded.rs
@@ -19,7 +19,11 @@ for ::std::option::Option<Bar<T>> {
     > = narrow::array::StructArray<Bar<T>, true, Buffer>;
 }
 impl<T: narrow::array::ArrayType<T>> narrow::array::StructArrayType for Bar<T> {
-    type Array<Buffer: narrow::buffer::BufferType> = BarArray<T, Buffer>;
+    type Array<
+        Buffer: narrow::buffer::BufferType,
+        OffsetItem: narrow::offset::OffsetElement,
+        UnionLayout: narrow::array::union::UnionType,
+    > = BarArray<T, Buffer>;
 }
 struct BarArray<T: narrow::array::ArrayType<T>, Buffer: narrow::buffer::BufferType> {
     a: <u32 as narrow::array::ArrayType<
diff --git a/narrow-derive/tests/expand/struct/named/simple.expanded.rs b/narrow-derive/tests/expand/struct/named/simple.expanded.rs
index b71658f..b2fb7e0 100644
--- a/narrow-derive/tests/expand/struct/named/simple.expanded.rs
+++ b/narrow-derive/tests/expand/struct/named/simple.expanded.rs
@@ -18,7 +18,11 @@ impl narrow::array::ArrayType<Foo> for ::std::option::Option<Foo> {
     > = narrow::array::StructArray<Foo, true, Buffer>;
 }
 impl narrow::array::StructArrayType for Foo {
-    type Array<Buffer: narrow::buffer::BufferType> = FooArray<Buffer>;
+    type Array<
+        Buffer: narrow::buffer::BufferType,
+        OffsetItem: narrow::offset::OffsetElement,
+        UnionLayout: narrow::array::union::UnionType,
+    > = FooArray<Buffer>;
 }
 struct FooArray<Buffer: narrow::buffer::BufferType> {
     a: <u32 as narrow::array::ArrayType<
diff --git a/narrow-derive/tests/expand/struct/unit/const_generic.expanded.rs b/narrow-derive/tests/expand/struct/unit/const_generic.expanded.rs
index 0f857a9..655eacc 100644
--- a/narrow-derive/tests/expand/struct/unit/const_generic.expanded.rs
+++ b/narrow-derive/tests/expand/struct/unit/const_generic.expanded.rs
@@ -19,7 +19,11 @@ impl<const N: usize> narrow::array::ArrayType<Foo<N>> for ::std::option::Option<
     > = narrow::array::StructArray<Foo<N>, true, Buffer>;
 }
 impl<const N: usize> narrow::array::StructArrayType for Foo<N> {
-    type Array<Buffer: narrow::buffer::BufferType> = FooArray<N, Buffer>;
+    type Array<
+        Buffer: narrow::buffer::BufferType,
+        OffsetItem: narrow::offset::OffsetElement,
+        UnionLayout: narrow::array::union::UnionType,
+    > = FooArray<N, Buffer>;
 }
 pub struct FooArray<const N: usize, Buffer: narrow::buffer::BufferType>(
     pub narrow::array::NullArray<Foo<N>, false, Buffer>,
diff --git a/narrow-derive/tests/expand/struct/unit/const_generic_default.expanded.rs b/narrow-derive/tests/expand/struct/unit/const_generic_default.expanded.rs
index 972f2f0..a9e699c 100644
--- a/narrow-derive/tests/expand/struct/unit/const_generic_default.expanded.rs
+++ b/narrow-derive/tests/expand/struct/unit/const_generic_default.expanded.rs
@@ -19,7 +19,11 @@ impl<const N: usize> narrow::array::ArrayType<Foo<N>> for ::std::option::Option<
     > = narrow::array::StructArray<Foo<N>, true, Buffer>;
 }
 impl<const N: usize> narrow::array::StructArrayType for Foo<N> {
-    type Array<Buffer: narrow::buffer::BufferType> = FooArray<N, Buffer>;
+    type Array<
+        Buffer: narrow::buffer::BufferType,
+        OffsetItem: narrow::offset::OffsetElement,
+        UnionLayout: narrow::array::union::UnionType,
+    > = FooArray<N, Buffer>;
 }
 pub struct FooArray<const N: usize, Buffer: narrow::buffer::BufferType>(
     pub narrow::array::NullArray<Foo<N>, false, Buffer>,
diff --git a/narrow-derive/tests/expand/struct/unit/self.expanded.rs b/narrow-derive/tests/expand/struct/unit/self.expanded.rs
index 61da210..f0bb5d3 100644
--- a/narrow-derive/tests/expand/struct/unit/self.expanded.rs
+++ b/narrow-derive/tests/expand/struct/unit/self.expanded.rs
@@ -33,7 +33,11 @@ impl narrow::array::StructArrayType for Foo
 where
     Self: Debug,
 {
-    type Array<Buffer: narrow::buffer::BufferType> = FooArray<Buffer>;
+    type Array<
+        Buffer: narrow::buffer::BufferType,
+        OffsetItem: narrow::offset::OffsetElement,
+        UnionLayout: narrow::array::union::UnionType,
+    > = FooArray<Buffer>;
 }
 struct FooArray<Buffer: narrow::buffer::BufferType>(
     narrow::array::NullArray<Foo, false, Buffer>,
diff --git a/narrow-derive/tests/expand/struct/unit/simple.expanded.rs b/narrow-derive/tests/expand/struct/unit/simple.expanded.rs
index e34b02f..6853eef 100644
--- a/narrow-derive/tests/expand/struct/unit/simple.expanded.rs
+++ b/narrow-derive/tests/expand/struct/unit/simple.expanded.rs
@@ -19,7 +19,11 @@ impl narrow::array::ArrayType<Foo> for ::std::option::Option<Foo> {
     > = narrow::array::StructArray<Foo, true, Buffer>;
 }
 impl narrow::array::StructArrayType for Foo {
-    type Array<Buffer: narrow::buffer::BufferType> = FooArray<Buffer>;
+    type Array<
+        Buffer: narrow::buffer::BufferType,
+        OffsetItem: narrow::offset::OffsetElement,
+        UnionLayout: narrow::array::union::UnionType,
+    > = FooArray<Buffer>;
 }
 struct FooArray<Buffer: narrow::buffer::BufferType>(
     narrow::array::NullArray<Foo, false, Buffer>,
diff --git a/narrow-derive/tests/expand/struct/unit/where_clause.expanded.rs b/narrow-derive/tests/expand/struct/unit/where_clause.expanded.rs
index 2dd37ca..d6d2917 100644
--- a/narrow-derive/tests/expand/struct/unit/where_clause.expanded.rs
+++ b/narrow-derive/tests/expand/struct/unit/where_clause.expanded.rs
@@ -38,7 +38,11 @@ where
     Self: Sized,
     (): From<Self>,
 {
-    type Array<Buffer: narrow::buffer::BufferType> = FooArray<N, Buffer>;
+    type Array<
+        Buffer: narrow::buffer::BufferType,
+        OffsetItem: narrow::offset::OffsetElement,
+        UnionLayout: narrow::array::union::UnionType,
+    > = FooArray<N, Buffer>;
 }
 pub(super) struct FooArray<const N: bool, Buffer: narrow::buffer::BufferType>(
     pub(super) narrow::array::NullArray<Foo<N>, false, Buffer>,
diff --git a/narrow-derive/tests/expand/struct/unnamed/generic.expanded.rs b/narrow-derive/tests/expand/struct/unnamed/generic.expanded.rs
index 18d3b4a..d43309e 100644
--- a/narrow-derive/tests/expand/struct/unnamed/generic.expanded.rs
+++ b/narrow-derive/tests/expand/struct/unnamed/generic.expanded.rs
@@ -34,7 +34,11 @@ where
     Self: Sized,
     <T as Add<Self>>::Output: Debug,
 {
-    type Array<Buffer: narrow::buffer::BufferType> = FooArray<'a, T, Buffer>;
+    type Array<
+        Buffer: narrow::buffer::BufferType,
+        OffsetItem: narrow::offset::OffsetElement,
+        UnionLayout: narrow::array::union::UnionType,
+    > = FooArray<'a, T, Buffer>;
 }
 struct FooArray<
     'a,
@@ -227,7 +231,11 @@ for ::std::option::Option<FooBar<T>> {
     > = narrow::array::StructArray<FooBar<T>, true, Buffer>;
 }
 impl<T: narrow::array::ArrayType<T>> narrow::array::StructArrayType for FooBar<T> {
-    type Array<Buffer: narrow::buffer::BufferType> = FooBarArray<T, Buffer>;
+    type Array<
+        Buffer: narrow::buffer::BufferType,
+        OffsetItem: narrow::offset::OffsetElement,
+        UnionLayout: narrow::array::union::UnionType,
+    > = FooBarArray<T, Buffer>;
 }
 struct FooBarArray<T: narrow::array::ArrayType<T>, Buffer: narrow::buffer::BufferType>(
     <T as narrow::array::ArrayType<
diff --git a/narrow-derive/tests/expand/struct/unnamed/lifetime.expanded.rs b/narrow-derive/tests/expand/struct/unnamed/lifetime.expanded.rs
index 45f9875..e3f89f2 100644
--- a/narrow-derive/tests/expand/struct/unnamed/lifetime.expanded.rs
+++ b/narrow-derive/tests/expand/struct/unnamed/lifetime.expanded.rs
@@ -16,7 +16,11 @@ for ::std::option::Option<Foo<'a, T>> {
     > = narrow::array::StructArray<Foo<'a, T>, true, Buffer>;
 }
 impl<'a, T: narrow::array::ArrayType<T>> narrow::array::StructArrayType for Foo<'a, T> {
-    type Array<Buffer: narrow::buffer::BufferType> = FooArray<'a, T, Buffer>;
+    type Array<
+        Buffer: narrow::buffer::BufferType,
+        OffsetItem: narrow::offset::OffsetElement,
+        UnionLayout: narrow::array::union::UnionType,
+    > = FooArray<'a, T, Buffer>;
 }
 struct FooArray<'a, T: narrow::array::ArrayType<T>, Buffer: narrow::buffer::BufferType>(
     <&'a T as narrow::array::ArrayType<
diff --git a/narrow-derive/tests/expand/struct/unnamed/multiple.expanded.rs b/narrow-derive/tests/expand/struct/unnamed/multiple.expanded.rs
index 702782c..254575c 100644
--- a/narrow-derive/tests/expand/struct/unnamed/multiple.expanded.rs
+++ b/narrow-derive/tests/expand/struct/unnamed/multiple.expanded.rs
@@ -14,7 +14,11 @@ impl narrow::array::ArrayType<Bar> for ::std::option::Option<Bar> {
     > = narrow::array::StructArray<Bar, true, Buffer>;
 }
 impl narrow::array::StructArrayType for Bar {
-    type Array<Buffer: narrow::buffer::BufferType> = BarArray<Buffer>;
+    type Array<
+        Buffer: narrow::buffer::BufferType,
+        OffsetItem: narrow::offset::OffsetElement,
+        UnionLayout: narrow::array::union::UnionType,
+    > = BarArray<Buffer>;
 }
 struct BarArray<Buffer: narrow::buffer::BufferType>(
     <u8 as narrow::array::ArrayType<
diff --git a/narrow-derive/tests/expand/struct/unnamed/nested.expanded.rs b/narrow-derive/tests/expand/struct/unnamed/nested.expanded.rs
index 4e7d468..2f94861 100644
--- a/narrow-derive/tests/expand/struct/unnamed/nested.expanded.rs
+++ b/narrow-derive/tests/expand/struct/unnamed/nested.expanded.rs
@@ -14,7 +14,11 @@ impl narrow::array::ArrayType<Foo> for ::std::option::Option<Foo> {
     > = narrow::array::StructArray<Foo, true, Buffer>;
 }
 impl narrow::array::StructArrayType for Foo {
-    type Array<Buffer: narrow::buffer::BufferType> = FooArray<Buffer>;
+    type Array<
+        Buffer: narrow::buffer::BufferType,
+        OffsetItem: narrow::offset::OffsetElement,
+        UnionLayout: narrow::array::union::UnionType,
+    > = FooArray<Buffer>;
 }
 struct FooArray<Buffer: narrow::buffer::BufferType>(
     <u32 as narrow::array::ArrayType<
@@ -152,7 +156,11 @@ impl narrow::array::ArrayType<Bar> for ::std::option::Option<Bar> {
     > = narrow::array::StructArray<Bar, true, Buffer>;
 }
 impl narrow::array::StructArrayType for Bar {
-    type Array<Buffer: narrow::buffer::BufferType> = BarArray<Buffer>;
+    type Array<
+        Buffer: narrow::buffer::BufferType,
+        OffsetItem: narrow::offset::OffsetElement,
+        UnionLayout: narrow::array::union::UnionType,
+    > = BarArray<Buffer>;
 }
 struct BarArray<Buffer: narrow::buffer::BufferType>(
     <Foo as narrow::array::ArrayType<
diff --git a/narrow-derive/tests/expand/struct/unnamed/nested_generic.expanded.rs b/narrow-derive/tests/expand/struct/unnamed/nested_generic.expanded.rs
index dd3a08e..e680d39 100644
--- a/narrow-derive/tests/expand/struct/unnamed/nested_generic.expanded.rs
+++ b/narrow-derive/tests/expand/struct/unnamed/nested_generic.expanded.rs
@@ -28,7 +28,11 @@ impl<T: narrow::array::ArrayType<T>> narrow::array::StructArrayType for Foo<T>
 where
     T: Copy,
 {
-    type Array<Buffer: narrow::buffer::BufferType> = FooArray<T, Buffer>;
+    type Array<
+        Buffer: narrow::buffer::BufferType,
+        OffsetItem: narrow::offset::OffsetElement,
+        UnionLayout: narrow::array::union::UnionType,
+    > = FooArray<T, Buffer>;
 }
 struct FooArray<T: narrow::array::ArrayType<T>, Buffer: narrow::buffer::BufferType>(
     <T as narrow::array::ArrayType<
@@ -196,7 +200,11 @@ for ::std::option::Option<Bar<'a, T>> {
     > = narrow::array::StructArray<Bar<'a, T>, true, Buffer>;
 }
 impl<'a, T: narrow::array::ArrayType<T>> narrow::array::StructArrayType for Bar<'a, T> {
-    type Array<Buffer: narrow::buffer::BufferType> = BarArray<'a, T, Buffer>;
+    type Array<
+        Buffer: narrow::buffer::BufferType,
+        OffsetItem: narrow::offset::OffsetElement,
+        UnionLayout: narrow::array::union::UnionType,
+    > = BarArray<'a, T, Buffer>;
 }
 struct BarArray<'a, T: narrow::array::ArrayType<T>, Buffer: narrow::buffer::BufferType>(
     <&'a Foo<
@@ -385,7 +393,11 @@ impl<'a> narrow::array::ArrayType<FooBar<'a>> for ::std::option::Option<FooBar<'
     > = narrow::array::StructArray<FooBar<'a>, true, Buffer>;
 }
 impl<'a> narrow::array::StructArrayType for FooBar<'a> {
-    type Array<Buffer: narrow::buffer::BufferType> = FooBarArray<'a, Buffer>;
+    type Array<
+        Buffer: narrow::buffer::BufferType,
+        OffsetItem: narrow::offset::OffsetElement,
+        UnionLayout: narrow::array::union::UnionType,
+    > = FooBarArray<'a, Buffer>;
 }
 struct FooBarArray<'a, Buffer: narrow::buffer::BufferType>(
     <Bar<
diff --git a/narrow-derive/tests/expand/struct/unnamed/simple.expanded.rs b/narrow-derive/tests/expand/struct/unnamed/simple.expanded.rs
index 49d8888..0166eca 100644
--- a/narrow-derive/tests/expand/struct/unnamed/simple.expanded.rs
+++ b/narrow-derive/tests/expand/struct/unnamed/simple.expanded.rs
@@ -16,7 +16,11 @@ for ::std::option::Option<Foo<T>> {
     > = narrow::array::StructArray<Foo<T>, true, Buffer>;
 }
 impl<T: Sized + narrow::array::ArrayType<T>> narrow::array::StructArrayType for Foo<T> {
-    type Array<Buffer: narrow::buffer::BufferType> = FooArray<T, Buffer>;
+    type Array<
+        Buffer: narrow::buffer::BufferType,
+        OffsetItem: narrow::offset::OffsetElement,
+        UnionLayout: narrow::array::union::UnionType,
+    > = FooArray<T, Buffer>;
 }
 struct FooArray<
     T: Sized + narrow::array::ArrayType<T>,