REF: make normalize_i8_timestamps cpdef (#34476)

Author: jbrockmendel

pandas/_libs/tslibs/conversion.pxd

@@ -1,6 +1,6 @@
-from cpython.datetime cimport datetime
+from cpython.datetime cimport datetime, tzinfo
 
-from numpy cimport int64_t, int32_t
+from numpy cimport int64_t, int32_t, ndarray
 
 from pandas._libs.tslibs.np_datetime cimport npy_datetimestruct
 
@@ -24,3 +24,5 @@ cdef int64_t get_datetime64_nanos(object val) except? -1
 
 cpdef datetime localize_pydatetime(datetime dt, object tz)
 cdef int64_t cast_from_unit(object ts, str unit) except? -1
+
+cpdef ndarray[int64_t] normalize_i8_timestamps(const int64_t[:] stamps, tzinfo tz)

pandas/_libs/tslibs/conversion.pyx

@@ -763,7 +763,7 @@ cpdef inline datetime localize_pydatetime(datetime dt, object tz):
 
 @cython.wraparound(False)
 @cython.boundscheck(False)
-def normalize_i8_timestamps(int64_t[:] stamps, object tz):
+cpdef ndarray[int64_t] normalize_i8_timestamps(const int64_t[:] stamps, tzinfo tz):
     """
     Normalize each of the (nanosecond) timezone aware timestamps in the given
     array by rounding down to the beginning of the day (i.e. midnight).
@@ -774,31 +774,6 @@ def normalize_i8_timestamps(int64_t[:] stamps, object tz):
     stamps : int64 ndarray
     tz : tzinfo or None
 
-    Returns
-    -------
-    result : int64 ndarray of converted of normalized nanosecond timestamps
-    """
-    cdef:
-        int64_t[:] result
-
-    result = _normalize_local(stamps, tz)
-
-    return result.base  # .base to access underlying np.ndarray
-
-
-@cython.wraparound(False)
-@cython.boundscheck(False)
-cdef int64_t[:] _normalize_local(const int64_t[:] stamps, tzinfo tz):
-    """
-    Normalize each of the (nanosecond) timestamps in the given array by
-    rounding down to the beginning of the day (i.e. midnight) for the
-    given timezone `tz`.
-
-    Parameters
-    ----------
-    stamps : int64 ndarray
-    tz : tzinfo
-
     Returns
     -------
     result : int64 ndarray of converted of normalized nanosecond timestamps
@@ -843,7 +818,7 @@ cdef int64_t[:] _normalize_local(const int64_t[:] stamps, tzinfo tz):
                 dt64_to_dtstruct(stamps[i] + deltas[pos[i]], &dts)
                 result[i] = _normalized_stamp(&dts)
 
-    return result
+    return result.base  # `.base` to access underlying ndarray
 
 
 cdef inline int64_t _normalized_stamp(npy_datetimestruct *dts) nogil:

pandas/_libs/tslibs/timestamps.pyx

@@ -16,8 +16,15 @@ cnp.import_array()
 from cpython.object cimport (PyObject_RichCompareBool, PyObject_RichCompare,
                              Py_GT, Py_GE, Py_EQ, Py_NE, Py_LT, Py_LE)
 
-from cpython.datetime cimport (datetime, time, PyDateTime_Check, PyDelta_Check,
-                               PyTZInfo_Check, PyDateTime_IMPORT)
+from cpython.datetime cimport (
+    datetime,
+    time,
+    tzinfo,
+    PyDateTime_Check,
+    PyDelta_Check,
+    PyTZInfo_Check,
+    PyDateTime_IMPORT,
+)
 PyDateTime_IMPORT
 
 from pandas._libs.tslibs.util cimport (
@@ -29,10 +36,12 @@ from pandas._libs.tslibs.base cimport ABCTimestamp
 
 from pandas._libs.tslibs cimport ccalendar
 
-from pandas._libs.tslibs.conversion import normalize_i8_timestamps
 from pandas._libs.tslibs.conversion cimport (
-    _TSObject, convert_to_tsobject,
-    convert_datetime_to_tsobject)
+    _TSObject,
+    convert_to_tsobject,
+    convert_datetime_to_tsobject,
+    normalize_i8_timestamps,
+)
 from pandas._libs.tslibs.fields import get_start_end_field, get_date_name_field
 from pandas._libs.tslibs.nattype cimport NPY_NAT, c_NaT as NaT
 from pandas._libs.tslibs.np_datetime cimport (
@@ -1438,13 +1447,18 @@ default 'raise'
         """
         Normalize Timestamp to midnight, preserving tz information.
         """
-        if self.tz is None or is_utc(self.tz):
+        cdef:
+            ndarray[int64_t] normalized
+            tzinfo own_tz = self.tzinfo  # could be None
+
+        if own_tz is None or is_utc(own_tz):
             DAY_NS = ccalendar.DAY_NANOS
             normalized_value = self.value - (self.value % DAY_NS)
-            return Timestamp(normalized_value).tz_localize(self.tz)
-        normalized_value = normalize_i8_timestamps(
-            np.array([self.value], dtype='i8'), tz=self.tz)[0]
-        return Timestamp(normalized_value).tz_localize(self.tz)
+            return Timestamp(normalized_value).tz_localize(own_tz)
+
+        normalized = normalize_i8_timestamps(
+            np.array([self.value], dtype='i8'), tz=own_tz)
+        return Timestamp(normalized[0]).tz_localize(own_tz)
 
 
 # Add the min and max fields at the class level