sketch

python/src/nanoarrow/extension.py

@@ -31,14 +31,13 @@ def get_pyiter(
     ) -> Optional[Iterator]:
         return None
 
-    def get_sequence_converter(
-        self, params, c_array_view: CArrayView, offset: int, length: int
-    ):
+    def get_sequence_converter(self, c_schema):
         return None
 
 
 global_extension_registry = {}
 
+
 def resolve_extension(c_schema_view: CSchemaView) -> Optional[Extension]:
     extension_name = c_schema_view.extension_name
     if extension_name in global_extension_registry:

python/src/nanoarrow/iterator.py

@@ -23,6 +23,7 @@
 from nanoarrow._array import CArrayView
 from nanoarrow.c_array_stream import c_array_stream
 from nanoarrow.c_schema import c_schema, c_schema_view
+from nanoarrow.extension import resolve_extension
 from nanoarrow.schema import Schema
 
 from nanoarrow import _types
@@ -183,6 +184,8 @@ def get_iterator(cls, obj, schema=None):
 
     def __init__(self, schema, *, array_view=None):
         super().__init__(schema, array_view=array_view)
+        self._ext = resolve_extension(self._schema_view)
+        self._ext_params = self._ext.get_params(schema) if self._ext else None
 
         self._children = list(
             map(self._make_child, self._schema.children, self._array_view.children)
@@ -208,11 +211,14 @@ def __iter__(self):
 
     def _iter_chunk(self, offset, length):
         """Iterate over all elements in a slice of the current chunk"""
+
         # Check for an extension type first since this isn't reflected by
         # self._schema_view.type_id. Currently we just return the storage
         # iterator with a warning for extension types.
         maybe_extension_name = self._schema_view.extension_name
-        if maybe_extension_name:
+        if self._ext:
+            return self._ext.get_pyiter(self._ext_params, self._array_view, offset, length)
+        elif maybe_extension_name:
             self._warn(
                 f"Converting unregistered extension '{maybe_extension_name}' "
                 "as storage type",

python/src/nanoarrow/meson.build

@@ -101,6 +101,7 @@ py_sources = [
     'c_buffer.py',
     'c_schema.py',
     'device.py',
+    'extension.py',
     'ipc.py',
     'iterator.py',
     '_repr_utils.py',

python/src/nanoarrow/visitor.py

@@ -21,6 +21,7 @@
 from nanoarrow._buffer import CBuffer, CBufferBuilder
 from nanoarrow.c_array_stream import c_array_stream
 from nanoarrow.c_schema import c_schema_view
+from nanoarrow.extension import resolve_extension
 from nanoarrow.iterator import ArrayViewBaseIterator, PyIterator
 from nanoarrow.schema import Type
 
@@ -428,9 +429,16 @@ def finish(self) -> Any:
 
 def _resolve_converter_cls(schema, handle_nulls=None):
     schema_view = c_schema_view(schema)
+    ext = resolve_extension(schema_view)
+    ext_converter_cls = ext.get_sequence_converter_cls(schema) if ext else None
 
     if schema_view.nullable:
-        if schema_view.type_id == _types.BOOL:
+        if ext_converter_cls:
+            return ToNullableSequenceConverter, {
+                "converter_cls": ext_converter_cls,
+                "handle_nulls": handle_nulls,
+            }
+        elif schema_view.type_id == _types.BOOL:
             return ToNullableSequenceConverter, {
                 "converter_cls": ToBooleanBufferConverter,
                 "handle_nulls": handle_nulls,
@@ -443,8 +451,9 @@ def _resolve_converter_cls(schema, handle_nulls=None):
         else:
             return ToPyListConverter, {}
     else:
-
-        if schema_view.type_id == _types.BOOL:
+        if ext_converter_cls:
+            return ext_converter_cls, {}
+        elif schema_view.type_id == _types.BOOL:
             return ToBooleanBufferConverter, {}
         elif schema_view.buffer_format is not None:
             return ToPyBufferConverter, {}