Add IndexingAdapter mixin

Author: dcherian

xarray/core/indexing.py

@@ -516,6 +516,20 @@ def get_duck_array(self):
         return self.array
 
 
+class IndexingAdapter:
+    """Marker class for indexing adapters.
+
+    These classes translate between Xarray's indexing semantics and the underlying array's
+    indexing semantics.
+    """
+
+    async def async_get_duck_array():
+        """These classes are applied to in-memory arrays, so async get isn't needed."""
+        raise RuntimeError(
+            f"{type(self).__name__} async_get_duck_array was called. This should not happen."
+        )
+
+
 class ExplicitlyIndexedNDArrayMixin(NDArrayMixin, ExplicitlyIndexed):
     __slots__ = ()
 
@@ -1589,7 +1603,7 @@ def is_fancy_indexer(indexer: Any) -> bool:
     return True
 
 
-class NumpyIndexingAdapter(ExplicitlyIndexedNDArrayMixin):
+class NumpyIndexingAdapter(ExplicitlyIndexedNDArrayMixin, IndexingAdapter):
     """Wrap a NumPy array to use explicit indexing."""
 
     __slots__ = ("array",)
@@ -1668,7 +1682,7 @@ def __init__(self, array):
         self.array = array
 
 
-class ArrayApiIndexingAdapter(ExplicitlyIndexedNDArrayMixin):
+class ArrayApiIndexingAdapter(ExplicitlyIndexedNDArrayMixin, IndexingAdapter):
     """Wrap an array API array to use explicit indexing."""
 
     __slots__ = ("array",)
@@ -1733,7 +1747,7 @@ def _assert_not_chunked_indexer(idxr: tuple[Any, ...]) -> None:
         )
 
 
-class DaskIndexingAdapter(ExplicitlyIndexedNDArrayMixin):
+class DaskIndexingAdapter(ExplicitlyIndexedNDArrayMixin, IndexingAdapter):
     """Wrap a dask array to support explicit indexing."""
 
     __slots__ = ("array",)
@@ -1809,7 +1823,7 @@ def transpose(self, order):
         return self.array.transpose(order)
 
 
-class PandasIndexingAdapter(ExplicitlyIndexedNDArrayMixin):
+class PandasIndexingAdapter(ExplicitlyIndexedNDArrayMixin, IndexingAdapter):
     """Wrap a pandas.Index to preserve dtypes and handle explicit indexing."""
 
     __slots__ = ("_dtype", "array")
@@ -2135,7 +2149,9 @@ def copy(self, deep: bool = True) -> Self:
         return type(self)(array, self._dtype, self.level)
 
 
-class CoordinateTransformIndexingAdapter(ExplicitlyIndexedNDArrayMixin):
+class CoordinateTransformIndexingAdapter(
+    ExplicitlyIndexedNDArrayMixin, IndexingAdapter
+):
     """Wrap a CoordinateTransform as a lazy coordinate array.
 
     Supports explicit indexing (both outer and vectorized).