REF: move bits of offsets to liboffsets, de-privatize

asv_bench/benchmarks/io/parsers.py

@@ -2,7 +2,7 @@
 
 try:
     from pandas._libs.tslibs.parsing import (
-        _concat_date_cols,
+        concat_date_cols,
         _does_string_look_like_datetime,
     )
 except ImportError:
@@ -39,4 +39,4 @@ def setup(self, value, dim):
             )
 
     def time_check_concat(self, value, dim):
-        _concat_date_cols(self.object)
+        concat_date_cols(self.object)

pandas/_libs/tslibs/frequencies.pyx

@@ -175,13 +175,13 @@ cpdef get_freq_code(freqstr):
     if is_integer_object(freqstr):
         return freqstr, 1
 
-    base, stride = _base_and_stride(freqstr)
+    base, stride = base_and_stride(freqstr)
     code = _period_str_to_code(base)
 
     return code, stride
 
 
-cpdef _base_and_stride(str freqstr):
+cpdef base_and_stride(str freqstr):
     """
     Return base freq and stride info from string representation
 
@@ -267,7 +267,7 @@ cpdef str get_base_alias(freqstr):
     -------
     base_alias : str
     """
-    return _base_and_stride(freqstr)[0]
+    return base_and_stride(freqstr)[0]
 
 
 cpdef int get_to_timestamp_base(int base):

pandas/_libs/tslibs/offsets.pyx

@@ -2,6 +2,7 @@ import cython
 
 import time
 from typing import Any
+import warnings
 from cpython.datetime cimport (PyDateTime_IMPORT,
                                PyDateTime_Check,
                                PyDelta_Check,
@@ -103,7 +104,7 @@ def as_datetime(obj):
     return obj
 
 
-cpdef bint _is_normalized(dt):
+cpdef bint is_normalized(dt):
     if (dt.hour != 0 or dt.minute != 0 or dt.second != 0 or
             dt.microsecond != 0 or getattr(dt, 'nanosecond', 0) != 0):
         return False
@@ -230,7 +231,7 @@ def _get_calendar(weekmask, holidays, calendar):
         holidays = holidays + calendar.holidays().tolist()
     except AttributeError:
         pass
-    holidays = [_to_dt64D(dt) for dt in holidays]
+    holidays = [to_dt64D(dt) for dt in holidays]
     holidays = tuple(sorted(holidays))
 
     kwargs = {'weekmask': weekmask}
@@ -241,7 +242,7 @@ def _get_calendar(weekmask, holidays, calendar):
     return busdaycalendar, holidays
 
 
-def _to_dt64D(dt):
+def to_dt64D(dt):
     # Currently
     # > np.datetime64(dt.datetime(2013,5,1),dtype='datetime64[D]')
     # numpy.datetime64('2013-05-01T02:00:00.000000+0200')
@@ -264,7 +265,7 @@ def _to_dt64D(dt):
 # Validation
 
 
-def _validate_business_time(t_input):
+def validate_business_time(t_input):
     if isinstance(t_input, str):
         try:
             t = time.strptime(t_input, '%H:%M')
@@ -440,6 +441,9 @@ class _BaseOffset:
         # that allows us to use methods that can go in a `cdef class`
         return self * 1
 
+    # ------------------------------------------------------------------
+    # Name and Rendering Methods
+
     def __repr__(self) -> str:
         className = getattr(self, '_outputName', type(self).__name__)
 
@@ -455,6 +459,44 @@ class _BaseOffset:
         out = f'<{n_str}{className}{plural}{self._repr_attrs()}>'
         return out
 
+    @property
+    def name(self) -> str:
+        return self.rule_code
+
+    @property
+    def _prefix(self) -> str:
+        raise NotImplementedError("Prefix not defined")
+
+    @property
+    def rule_code(self) -> str:
+        return self._prefix
+
+    @property
+    def freqstr(self) -> str:
+        try:
+            code = self.rule_code
+        except NotImplementedError:
+            return str(repr(self))
+
+        if self.n != 1:
+            fstr = f"{self.n}{code}"
+        else:
+            fstr = code
+
+        try:
+            if self._offset:
+                fstr += self._offset_str()
+        except AttributeError:
+            # TODO: standardize `_offset` vs `offset` naming convention
+            pass
+
+        return fstr
+
+    def _offset_str(self) -> str:
+        return ""
+
+    # ------------------------------------------------------------------
+
     def _get_offset_day(self, datetime other):
         # subclass must implement `_day_opt`; calling from the base class
         # will raise NotImplementedError.
@@ -530,6 +572,26 @@ class _BaseOffset:
 
         return state
 
+    @property
+    def nanos(self):
+        raise ValueError(f"{self} is a non-fixed frequency")
+
+    def onOffset(self, dt) -> bool:
+        warnings.warn(
+            "onOffset is a deprecated, use is_on_offset instead",
+            FutureWarning,
+            stacklevel=1,
+        )
+        return self.is_on_offset(dt)
+
+    def isAnchored(self) -> bool:
+        warnings.warn(
+            "isAnchored is a deprecated, use is_anchored instead",
+            FutureWarning,
+            stacklevel=1,
+        )
+        return self.is_anchored()
+
 
 class BaseOffset(_BaseOffset):
     # Here we add __rfoo__ methods that don't play well with cdef classes
@@ -564,6 +626,49 @@ class _Tick:
         return _wrap_timedelta_result(result)
 
 
+class BusinessMixin:
+    """
+    Mixin to business types to provide related functions.
+    """
+
+    @property
+    def offset(self):
+        """
+        Alias for self._offset.
+        """
+        # Alias for backward compat
+        return self._offset
+
+    def _repr_attrs(self) -> str:
+        if self.offset:
+            attrs = [f"offset={repr(self.offset)}"]
+        else:
+            attrs = []
+        out = ""
+        if attrs:
+            out += ": " + ", ".join(attrs)
+        return out
+
+
+class CustomMixin:
+    """
+    Mixin for classes that define and validate calendar, holidays,
+    and weekdays attributes.
+    """
+
+    def __init__(self, weekmask, holidays, calendar):
+        calendar, holidays = _get_calendar(
+            weekmask=weekmask, holidays=holidays, calendar=calendar
+        )
+        # Custom offset instances are identified by the
+        # following two attributes. See DateOffset._params()
+        # holidays, weekmask
+
+        object.__setattr__(self, "weekmask", weekmask)
+        object.__setattr__(self, "holidays", holidays)
+        object.__setattr__(self, "calendar", calendar)
+
+
 # ----------------------------------------------------------------------
 # RelativeDelta Arithmetic
 

pandas/_libs/tslibs/parsing.pyx

@@ -938,7 +938,7 @@ cdef inline object convert_to_unicode(object item, bint keep_trivial_numbers):
 
 @cython.wraparound(False)
 @cython.boundscheck(False)
-def _concat_date_cols(tuple date_cols, bint keep_trivial_numbers=True):
+def concat_date_cols(tuple date_cols, bint keep_trivial_numbers=True):
     """
     Concatenates elements from numpy arrays in `date_cols` into strings.
 
@@ -957,7 +957,7 @@ def _concat_date_cols(tuple date_cols, bint keep_trivial_numbers=True):
     --------
     >>> dates=np.array(['3/31/2019', '4/31/2019'], dtype=object)
     >>> times=np.array(['11:20', '10:45'], dtype=object)
-    >>> result = _concat_date_cols((dates, times))
+    >>> result = concat_date_cols((dates, times))
     >>> result
     array(['3/31/2019 11:20', '4/31/2019 10:45'], dtype=object)
     """

pandas/_libs/tslibs/period.pyx

@@ -1685,7 +1685,7 @@ cdef class _Period:
         resampled : Period
         """
         freq = self._maybe_convert_freq(freq)
-        how = _validate_end_alias(how)
+        how = validate_end_alias(how)
         base1, mult1 = get_freq_code(self.freq)
         base2, mult2 = get_freq_code(freq)
 
@@ -1758,7 +1758,7 @@ cdef class _Period:
         """
         if freq is not None:
             freq = self._maybe_convert_freq(freq)
-        how = _validate_end_alias(how)
+        how = validate_end_alias(how)
 
         end = how == 'E'
         if end:
@@ -2509,7 +2509,7 @@ def quarter_to_myear(year: int, quarter: int, freq):
     return year, month
 
 
-def _validate_end_alias(how):
+def validate_end_alias(how):
     how_dict = {'S': 'S', 'E': 'E',
                 'START': 'S', 'FINISH': 'E',
                 'BEGIN': 'S', 'END': 'E'}

pandas/core/arrays/datetimes.py

@@ -1115,7 +1115,7 @@ def to_period(self, freq=None):
 
             #  https://github.com/pandas-dev/pandas/issues/33358
             if res is None:
-                base, stride = libfrequencies._base_and_stride(freq)
+                base, stride = libfrequencies.base_and_stride(freq)
                 res = f"{stride}{base}"
 
             freq = res

pandas/core/arrays/period.py

@@ -432,7 +432,7 @@ def to_timestamp(self, freq=None, how="start"):
         """
         from pandas.core.arrays import DatetimeArray
 
-        how = libperiod._validate_end_alias(how)
+        how = libperiod.validate_end_alias(how)
 
         end = how == "E"
         if end:
@@ -524,7 +524,7 @@ def asfreq(self, freq=None, how: str = "E") -> "PeriodArray":
         PeriodIndex(['2010-01', '2011-01', '2012-01', '2013-01', '2014-01',
         '2015-01'], dtype='period[M]', freq='M')
         """
-        how = libperiod._validate_end_alias(how)
+        how = libperiod.validate_end_alias(how)
 
         freq = Period._maybe_convert_freq(freq)
 

pandas/io/parsers.py

@@ -3264,7 +3264,7 @@ def _make_date_converter(
 ):
     def converter(*date_cols):
         if date_parser is None:
-            strs = parsing._concat_date_cols(date_cols)
+            strs = parsing.concat_date_cols(date_cols)
 
             try:
                 return tools.to_datetime(
@@ -3292,7 +3292,7 @@ def converter(*date_cols):
                 try:
                     return tools.to_datetime(
                         parsing.try_parse_dates(
-                            parsing._concat_date_cols(date_cols),
+                            parsing.concat_date_cols(date_cols),
                             parser=date_parser,
                             dayfirst=dayfirst,
                         ),

pandas/tests/io/parser/test_parse_dates.py

@@ -81,7 +81,7 @@ def date_parser(*date_cols):
         -------
         parsed : Series
         """
-        return parsing.try_parse_dates(parsing._concat_date_cols(date_cols))
+        return parsing.try_parse_dates(parsing.concat_date_cols(date_cols))
 
     result = parser.read_csv(
         StringIO(data),
@@ -208,7 +208,7 @@ def test_concat_date_col_fail(container, dim):
     date_cols = tuple(container([value]) for _ in range(dim))
 
     with pytest.raises(ValueError, match=msg):
-        parsing._concat_date_cols(date_cols)
+        parsing.concat_date_cols(date_cols)
 
 
 @pytest.mark.parametrize("keep_date_col", [True, False])

pandas/tseries/frequencies.py

@@ -124,7 +124,7 @@ def to_offset(freq) -> Optional[DateOffset]:
         stride = freq[1]
         if isinstance(stride, str):
             name, stride = stride, name
-        name, _ = libfreqs._base_and_stride(name)
+        name, _ = libfreqs.base_and_stride(name)
         delta = _get_offset(name) * stride
 
     elif isinstance(freq, timedelta):