explicit implementation of __reversed__

Author: flexatone

src/__init__.pyi

@@ -45,6 +45,7 @@ class BlockIndex:
     def copy(self,) -> 'BlockIndex': ...
     def __len__(self,) -> int: ...
     def __iter__(self,) -> tp.Iterator[tp.Tuple[int, int]]: ...
+    def __reversed__(self,) -> tp.Iterator[tp.Tuple[int, int]]: ...
     def __getitem__(self, __key: int) -> tp.Tuple[int, int]: ...
     def __getstate__(self,) -> tp.Tuple[int, int, int, int, bytes]: ...
     def __setstate__(self, state: tp.Tuple[int, int, int, int, bytes]) -> None: ...

src/_arraykit.c

@@ -5564,7 +5564,12 @@ BlockIndex_get_column(BlockIndexObject *self, PyObject *key){
 
 static PyObject*
 BlockIndex_iter(BlockIndexObject* self) {
-    return BIIter_new(self, 0);
+    return BIIter_new(self, false);
+}
+
+static PyObject*
+BlockIndex_reversed(BlockIndexObject* self) {
+    return BIIter_new(self, true);
 }
 
 // Given key, return an iterator of a selection.
@@ -5626,6 +5631,7 @@ static PyMethodDef BlockIndex_methods[] = {
     {"__getstate__", (PyCFunction) BlockIndex_getstate, METH_NOARGS, NULL},
     {"__setstate__", (PyCFunction) BlockIndex_setstate, METH_O, NULL},
     {"__sizeof__", (PyCFunction) BlockIndex_sizeof, METH_NOARGS, NULL},
+    {"__reversed__", (PyCFunction) BlockIndex_reversed, METH_NOARGS, NULL},
     {"to_list", (PyCFunction)BlockIndex_to_list, METH_NOARGS, NULL},
     {"to_bytes", (PyCFunction)BlockIndex_to_bytes, METH_NOARGS, NULL},
     {"copy", (PyCFunction)BlockIndex_copy, METH_NOARGS, NULL},

test/test_block_index.py

@@ -327,7 +327,7 @@ def test_block_index_get_column_a(self) -> None:
 
 
     #---------------------------------------------------------------------------
-    def test_block_index_iter_a(self) -> None:
+    def test_block_index_iter_a1(self) -> None:
         bi1 = BlockIndex()
         bi1.register(np.arange(2))
         bi1.register(np.arange(6).reshape(2,3))
@@ -339,9 +339,7 @@ def test_block_index_iter_a(self) -> None:
         self.assertEqual(list(bi1), [(0, 0), (1, 0), (1, 1), (1, 2), (2, 0)])
         self.assertEqual(list(reversed(bi1)), [(2, 0), (1, 2), (1, 1), (1, 0), (0, 0)])
 
-
-    #---------------------------------------------------------------------------
-    def test_block_index_iter_a(self) -> None:
+    def test_block_index_iter_a2(self) -> None:
         bi1 = BlockIndex()
         bi1.register(np.arange(4).reshape(2,2))
         bi1.register(np.arange(2))