Support buffer protocol objects as advanced index keys

CHANGELOG.md

@@ -8,6 +8,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+* Added support for buffer protocol objects as advanced index keys in `dpnp.ndarray` [#2889](https://github.com/IntelPython/dpnp/pull/2889)
+
 ### Changed
 
 ### Deprecated

dpnp/dpnp_array.py

@@ -52,26 +52,31 @@ def _unwrap_index_element(x):
     """
     Unwrap a single index element for the tensor indexing layer.
 
-    Converts dpnp arrays to usm_ndarray and array-like objects (range, list)
-    to numpy arrays with intp dtype for NumPy-compatible advanced indexing.
+    Converts dpnp arrays to usm_ndarray and array-like objects (range, list,
+    buffer protocol objects) to numpy arrays for NumPy-compatible advanced
+    indexing. Scalars and slices pass through to the tensor layer.
 
     """
 
-    if isinstance(x, dpt.usm_ndarray):
+    if (
+        x is None
+        or x is Ellipsis
+        or isinstance(x, (dpt.usm_ndarray, slice, numpy.ndarray))
+    ):
         return x
     if isinstance(x, dpnp_array):
         return x.get_array()
-    if isinstance(x, range):
-        return numpy.asarray(x, dtype=numpy.intp)
-    if isinstance(x, list):
-        # keep boolean lists as boolean
-        arr = numpy.asarray(x)
-        # cast empty lists (float64 in NumPy) to intp
-        # for correct tensor indexing
-        if arr.size == 0:
-            arr = arr.astype(numpy.intp)
-        return arr
-    return x
+    # scalars (int, bool, numpy scalars) pass through to the tensor layer
+    if isinstance(x, (int, numpy.generic)):
+        return x
+
+    # convert array-like objects (range, list, buffer protocol) to numpy
+    arr = numpy.asarray(x)
+    # cast empty arrays (float64 in NumPy) to intp
+    # for correct tensor indexing
+    if arr.size == 0 and arr.dtype.kind == "f":
+        arr = arr.astype(numpy.intp)
+    return arr
 
 
 def _get_unwrapped_index_key(key):

dpnp/tests/test_indexing.py

@@ -1,3 +1,4 @@
+import array
 import functools
 
 import dpctl
@@ -406,6 +407,65 @@ def test_array_like_single_index(self, idx):
         dp_a = dpnp.arange(24).reshape(2, 3, 4)
         assert_array_equal(dp_a[idx], np_a[idx])
 
+    def test_buffer_protocol_getitem(self):
+        inds = array.array("l")
+        inds.frombytes(numpy.arange(3).tobytes())
+        np_a = numpy.arange(12).reshape(3, 4)
+        dp_a = dpnp.arange(12).reshape(3, 4)
+        assert_array_equal(dp_a[inds], np_a[inds])
+
+    def test_buffer_protocol_paired_index(self):
+        inds = array.array("l")
+        inds.frombytes(numpy.arange(3).tobytes())
+        np_a = numpy.arange(12).reshape(3, 4)
+        dp_a = dpnp.arange(12).reshape(3, 4)
+        assert_array_equal(dp_a[inds, inds], np_a[inds, inds])
+
+    def test_buffer_protocol_setitem(self):
+        inds = array.array("l")
+        inds.frombytes(numpy.arange(3).tobytes())
+        np_a = numpy.arange(12).reshape(3, 4)
+        dp_a = dpnp.arange(12).reshape(3, 4)
+        np_a[inds, inds] = 0
+        dp_a[inds, inds] = 0
+        assert_array_equal(dp_a, np_a)
+
+    def test_memoryview_getitem(self):
+        inds = memoryview(array.array("l", [0, 1, 2]))
+        np_a = numpy.arange(12).reshape(3, 4)
+        dp_a = dpnp.arange(12).reshape(3, 4)
+        assert_array_equal(dp_a[inds], np_a[inds])
+
+    def test_bytearray_getitem(self):
+        inds = bytearray(b"\x00\x01\x02")
+        np_a = numpy.arange(10)
+        dp_a = dpnp.arange(10)
+        assert_array_equal(dp_a[inds], np_a[inds])
+
+    @pytest.mark.parametrize(
+        "idx",
+        [
+            1.0,
+            1 + 0j,
+            numpy.float64(1.0),
+            numpy.complex128(1.0),
+            "a",
+            [0.5, 1.5],
+        ],
+        ids=[
+            "float",
+            "complex",
+            "np.float64",
+            "np.complex128",
+            "str",
+            "float_list",
+        ],
+    )
+    def test_invalid_index(self, idx):
+        dp_a = dpnp.arange(12).reshape(3, 4)
+        with pytest.raises((IndexError, TypeError)):
+            dp_a[idx]
+
 
 class TestIx:
     @pytest.mark.parametrize(