Implement scans and reductions in pylibcudf

docs/cudf/source/user_guide/api_docs/pylibcudf/index.rst

@@ -15,6 +15,7 @@ This page provides API documentation for pylibcudf.
     gpumemoryview
     groupby
     join
+    reduce
     scalar
     table
     types

docs/cudf/source/user_guide/api_docs/pylibcudf/reduce.rst

@@ -0,0 +1,6 @@
+======
+reduce
+======
+
+.. automodule:: cudf._lib.pylibcudf.reduce
+   :members:

python/cudf/cudf/_lib/aggregation.pxd

@@ -3,28 +3,14 @@
 from libcpp.memory cimport unique_ptr
 
 from cudf._lib cimport pylibcudf
-from cudf._lib.cpp.aggregation cimport (
-    groupby_aggregation,
-    groupby_scan_aggregation,
-    reduce_aggregation,
-    rolling_aggregation,
-    scan_aggregation,
-)
+from cudf._lib.cpp.aggregation cimport rolling_aggregation
 
 
 cdef class RollingAggregation:
     cdef unique_ptr[rolling_aggregation] c_obj
 
-cdef class GroupbyAggregation:
+cdef class Aggregation:
     cdef pylibcudf.aggregation.Aggregation c_obj
 
-cdef class ReduceAggregation:
-    cdef unique_ptr[reduce_aggregation] c_obj
-
-cdef class ScanAggregation:
-    cdef unique_ptr[scan_aggregation] c_obj
-
 cdef RollingAggregation make_rolling_aggregation(op, kwargs=*)
-cdef GroupbyAggregation make_groupby_aggregation(op, kwargs=*)
-cdef ReduceAggregation make_reduce_aggregation(op, kwargs=*)
-cdef ScanAggregation make_scan_aggregation(op, kwargs=*)
+cdef Aggregation make_aggregation(op, kwargs=*)