Implement _is_utc in timezones

pandas/_libs/index.pyx

@@ -17,6 +17,7 @@ cimport tslib
 
 from hashtable cimport HashTable
 
+from tslibs.timezones cimport _is_utc
 from pandas._libs import tslib, algos, hashtable as _hash
 from pandas._libs.tslib import Timestamp, Timedelta
 from datetime import datetime, timedelta
@@ -32,9 +33,6 @@ cdef extern from "datetime.h":
 
 cdef int64_t iNaT = util.get_nat()
 
-from dateutil.tz import tzutc as _du_utc
-import pytz
-UTC = pytz.utc
 
 PyDateTime_IMPORT
 
@@ -559,9 +557,6 @@ cdef inline _to_i8(object val):
             return ival
         return val
 
-cdef inline bint _is_utc(object tz):
-    return tz is UTC or isinstance(tz, _du_utc)
-
 
 cdef class MultiIndexObjectEngine(ObjectEngine):
     """

pandas/_libs/period.pyx

@@ -33,9 +33,9 @@ from lib cimport is_null_datetimelike, is_period
 from pandas._libs import tslib, lib
 from pandas._libs.tslib import (Timedelta, Timestamp, iNaT,
                                 NaT, _get_utcoffset)
+from tslibs.timezones cimport _is_utc
 from tslib cimport (
     maybe_get_tz,
-    _is_utc,
     _is_tzlocal,
     _get_dst_info,
     _nat_scalar_rules)

pandas/_libs/tslib.pxd

@@ -3,7 +3,6 @@ from numpy cimport ndarray, int64_t
 cdef convert_to_tsobject(object, object, object, bint, bint)
 cpdef convert_to_timedelta64(object, object)
 cpdef object maybe_get_tz(object)
-cdef bint _is_utc(object)
 cdef bint _is_tzlocal(object)
 cdef object _get_dst_info(object)
 cdef bint _nat_scalar_rules[6]

pandas/_libs/tslib.pyx

@@ -107,6 +107,8 @@ cdef int64_t NPY_NAT = util.get_nat()
 iNaT = NPY_NAT
 
 
+from tslibs.timezones cimport _is_utc
+
 cdef inline object create_timestamp_from_ts(
         int64_t value, pandas_datetimestruct dts,
         object tz, object freq):
@@ -1702,8 +1704,6 @@ def _localize_pydatetime(object dt, object tz):
 def get_timezone(tz):
     return _get_zone(tz)
 
-cdef inline bint _is_utc(object tz):
-    return tz is UTC or isinstance(tz, _dateutil_tzutc)
 
 cdef inline object _get_zone(object tz):
     """

pandas/_libs/tslibs/__init__.py

@@ -0,0 +1,2 @@
+# -*- coding: utf-8 -*-
+# cython: profile=False

pandas/_libs/tslibs/timezones.pxd

@@ -0,0 +1,4 @@
+# -*- coding: utf-8 -*-
+# cython: profile=False
+
+cdef bint _is_utc(object tz)

pandas/_libs/tslibs/timezones.pyx

@@ -0,0 +1,40 @@
+# -*- coding: utf-8 -*-
+# cython: profile=False
+
+from pandas.compat import string_types, is_platform_windows
+
+cdef extern from "Python.h":
+    Py_ssize_t PY_SSIZE_T_MAX
+
+cdef extern from "datetime.h":
+    void PyDateTime_IMPORT()
+
+# import datetime C API
+PyDateTime_IMPORT
+
+import numpy as np
+cimport numpy as np
+from numpy cimport ndarray, int64_t, float64_t
+np.import_array()
+
+
+# dateutil compat
+from dateutil.tz import (tzoffset,
+                         tzlocal as _dateutil_tzlocal,
+                         tzfile as _dateutil_tzfile,
+                         tzutc as _dateutil_tzutc,
+                         tzstr as _dateutil_tzstr)
+
+if is_platform_windows():
+    from dateutil.zoneinfo import gettz as _dateutil_gettz
+else:
+    from dateutil.tz import gettz as _dateutil_gettz
+
+
+from pytz.tzinfo import BaseTzInfo as _pytz_BaseTzInfo
+import pytz
+UTC = pytz.utc
+
+
+cdef inline bint _is_utc(object tz):
+    return tz is UTC or isinstance(tz, _dateutil_tzutc)

setup.py

@@ -341,6 +341,7 @@ class CheckSDist(sdist_class):
                  'pandas/_libs/window.pyx',
                  'pandas/_libs/sparse.pyx',
                  'pandas/_libs/parsers.pyx',
+                 'pandas/_libs/tslibs/timezones.pyx',
                  'pandas/io/sas/sas.pyx']
 
     def initialize_options(self):
@@ -483,20 +484,24 @@ def pxd(name):
                                     + _pxi_dep['hashtable'])},
     '_libs.tslib': {'pyxfile': '_libs/tslib',
                     'pxdfiles': ['_libs/src/util', '_libs/lib'],
-                    'depends': tseries_depends,
+                    'depends': tseries_depends + [
+                               'pandas/_libs/tslibs/timezones'],
                     'sources': ['pandas/_libs/src/datetime/np_datetime.c',
                                 'pandas/_libs/src/datetime/np_datetime_strings.c',
                                 'pandas/_libs/src/period_helper.c']},
+    '_libs.tslibs.timezones': {'pyxfile': '_libs/tslibs/timezones'},
     '_libs.period': {'pyxfile': '_libs/period',
-                     'depends': tseries_depends,
+                     'depends': tseries_depends + [
+                                'pandas/_libs/tslibs/timezones'],
                      'sources': ['pandas/_libs/src/datetime/np_datetime.c',
                                  'pandas/_libs/src/datetime/np_datetime_strings.c',
                                  'pandas/_libs/src/period_helper.c']},
     '_libs.index': {'pyxfile': '_libs/index',
                     'sources': ['pandas/_libs/src/datetime/np_datetime.c',
                                 'pandas/_libs/src/datetime/np_datetime_strings.c'],
                     'pxdfiles': ['_libs/src/util', '_libs/hashtable'],
-                    'depends': _pxi_dep['index']},
+                    'depends': _pxi_dep['index'] + [
+                               'pandas/_libs/tslibs/timezones']},
     '_libs.algos': {'pyxfile': '_libs/algos',
                     'pxdfiles': ['_libs/src/util', '_libs/algos', '_libs/hashtable'],
                     'depends': _pxi_dep['algos']},