Migrate string case operations to pylibcudf

python/cudf/cudf/_lib/cpp/strings/case.pxd

@@ -1,11 +1,17 @@
-# Copyright (c) 2020, NVIDIA CORPORATION.
+# Copyright (c) 2020-2024, NVIDIA CORPORATION.
 from libcpp.memory cimport unique_ptr
 
 from cudf._lib.cpp.column.column cimport column
 from cudf._lib.cpp.column.column_view cimport column_view
 
 
 cdef extern from "cudf/strings/case.hpp" namespace "cudf::strings" nogil:
+    cdef unique_ptr[column] capitalize(
+        const column_view & input) except +
+
+    cdef unique_ptr[column] is_title(
+        const column_view & input) except +
+
     cdef unique_ptr[column] to_lower(
         const column_view & strings) except +
 

python/cudf/cudf/_lib/pylibcudf/CMakeLists.txt

@@ -44,3 +44,5 @@ rapids_cython_create_modules(
   LINKED_LIBRARIES "${linked_libraries}" MODULE_PREFIX pylibcudf_ ASSOCIATED_TARGETS cudf
 )
 link_to_pyarrow_headers(pylibcudf_interop)
+
+add_subdirectory(strings)

python/cudf/cudf/_lib/pylibcudf/__init__.pxd

@@ -17,6 +17,7 @@ from . cimport (
     search,
     sorting,
     stream_compaction,
+    strings,
     types,
     unary,
 )
@@ -48,6 +49,7 @@ __all__ = [
     "rolling",
     "search",
     "stream_compaction",
+    "strings",
     "sorting",
     "types",
     "unary",

python/cudf/cudf/_lib/pylibcudf/__init__.py

@@ -17,6 +17,7 @@
     search,
     sorting,
     stream_compaction,
+    strings,
     types,
     unary,
 )
@@ -48,6 +49,7 @@
     "rolling",
     "search",
     "stream_compaction",
+    "strings",
     "sorting",
     "types",
     "unary",

python/cudf/cudf/_lib/pylibcudf/strings/CMakeLists.txt

@@ -0,0 +1,21 @@
+# =============================================================================
+# Copyright (c) 2023-2024, NVIDIA CORPORATION.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+# in compliance with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software distributed under the License
+# is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+# or implied. See the License for the specific language governing permissions and limitations under
+# the License.
+# =============================================================================
+
+set(cython_sources case.pyx)
+set(linked_libraries cudf::cudf)
+rapids_cython_create_modules(
+  CXX
+  SOURCE_FILES "${cython_sources}"
+  LINKED_LIBRARIES "${linked_libraries}" MODULE_PREFIX pylibcudf_ ASSOCIATED_TARGETS cudf
+)

python/cudf/cudf/_lib/pylibcudf/strings/case.pxd

@@ -0,0 +1,8 @@
+# Copyright (c) 2024, NVIDIA CORPORATION.
+
+from cudf._lib.pylibcudf.column cimport Column
+
+
+cpdef Column to_lower(Column input)
+cpdef Column to_upper(Column input)
+cpdef Column swapcase(Column input)

python/cudf/cudf/_lib/pylibcudf/strings/case.pyx

@@ -0,0 +1,30 @@
+# Copyright (c) 2024, NVIDIA CORPORATION.
+
+from libcpp.memory cimport unique_ptr
+from libcpp.utility cimport move
+
+from cudf._lib.cpp.column.column cimport column
+from cudf._lib.cpp.strings cimport case as cpp_case
+from cudf._lib.pylibcudf.column cimport Column
+
+
+cpdef Column to_lower(Column input):
+    cdef unique_ptr[column] c_result
+    with nogil:
+        c_result = cpp_case.to_lower(input.view())
+
+    return Column.from_libcudf(move(c_result))
+
+cpdef Column to_upper(Column input):
+    cdef unique_ptr[column] c_result
+    with nogil:
+        c_result = cpp_case.to_upper(input.view())
+
+    return Column.from_libcudf(move(c_result))
+
+cpdef Column swapcase(Column input):
+    cdef unique_ptr[column] c_result
+    with nogil:
+        c_result = cpp_case.swapcase(input.view())
+
+    return Column.from_libcudf(move(c_result))

python/cudf/cudf/_lib/strings/case.pyx

@@ -1,48 +1,34 @@
-# Copyright (c) 2018-2022, NVIDIA CORPORATION.
+# Copyright (c) 2018-2024, NVIDIA CORPORATION.
 
 from cudf.core.buffer import acquire_spill_lock
 
-from libcpp.memory cimport unique_ptr
-from libcpp.utility cimport move
-
 from cudf._lib.column cimport Column
-from cudf._lib.cpp.column.column cimport column
-from cudf._lib.cpp.column.column_view cimport column_view
-from cudf._lib.cpp.strings.case cimport (
-    swapcase as cpp_swapcase,
-    to_lower as cpp_to_lower,
-    to_upper as cpp_to_upper,
-)
+
+from cudf._lib.pylibcudf.strings import case
 
 
 @acquire_spill_lock()
 def to_upper(Column source_strings):
-    cdef unique_ptr[column] c_result
-    cdef column_view source_view = source_strings.view()
-
-    with nogil:
-        c_result = move(cpp_to_upper(source_view))
-
-    return Column.from_unique_ptr(move(c_result))
+    return Column.from_pylibcudf(
+            case.to_upper(
+                source_strings.to_pylibcudf(mode='read')
+            )
+    )
 
 
 @acquire_spill_lock()
 def to_lower(Column source_strings):
-    cdef unique_ptr[column] c_result
-    cdef column_view source_view = source_strings.view()
-
-    with nogil:
-        c_result = move(cpp_to_lower(source_view))
-
-    return Column.from_unique_ptr(move(c_result))
+    return Column.from_pylibcudf(
+            case.to_lower(
+                source_strings.to_pylibcudf(mode='read')
+            )
+    )
 
 
 @acquire_spill_lock()
 def swapcase(Column source_strings):
-    cdef unique_ptr[column] c_result
-    cdef column_view source_view = source_strings.view()
-
-    with nogil:
-        c_result = move(cpp_swapcase(source_view))
-
-    return Column.from_unique_ptr(move(c_result))
+    return Column.from_pylibcudf(
+            case.swapcase(
+                source_strings.to_pylibcudf(mode='read')
+            )
+    )

python/cudf/cudf/pylibcudf_tests/test_string_case.py

@@ -0,0 +1,60 @@
+# Copyright (c) 2024, NVIDIA CORPORATION.
+
+import pyarrow as pa
+import pytest
+from utils import assert_column_eq
+
+import cudf._lib.pylibcudf as plc
+from cudf._lib.pylibcudf.strings import case
+
+
+@pytest.fixture(scope="module")
+def string_col():
+    return pa.array(
+        ["AbC", "de", "FGHI", "j", "kLm", "nOPq", None, "RsT", None, "uVw"]
+    )
+
+
+def wrap_nulls(func):
+    def wrapper(x):
+        if x is None:
+            return None
+        return func(x)
+
+    return wrapper
+
+
+def test_to_upper(string_col):
+    plc_col = plc.interop.from_arrow(string_col)
+    got = case.to_upper(plc_col)
+
+    @wrap_nulls
+    def to_upper(x):
+        return x.upper()
+
+    expected = pa.Array.from_pandas(string_col.to_pandas().apply(to_upper))
+    assert_column_eq(got, expected)
+
+
+def test_to_lower(string_col):
+    plc_col = plc.interop.from_arrow(string_col)
+    got = case.to_lower(plc_col)
+
+    @wrap_nulls
+    def to_lower(x):
+        return x.lower()
+
+    expected = pa.Array.from_pandas(string_col.to_pandas().apply(to_lower))
+    assert_column_eq(got, expected)
+
+
+def test_swapcase(string_col):
+    plc_col = plc.interop.from_arrow(string_col)
+    got = case.swapcase(plc_col)
+
+    @wrap_nulls
+    def swapcase(x):
+        return x.swapcase()
+
+    expected = pa.Array.from_pandas(string_col.to_pandas().apply(swapcase))
+    assert_column_eq(got, expected)