CLN: remove cython<3 reversed-op pattern

pandas/_libs/interval.pyx

@@ -495,17 +495,6 @@ cdef class Interval(IntervalMixin):
             or cnp.is_timedelta64_object(y)
         ):
             return Interval(self.left + y, self.right + y, closed=self.closed)
-        elif (
-            # __radd__ pattern
-            # TODO(cython3): remove this
-            isinstance(y, Interval)
-            and (
-                isinstance(self, numbers.Number)
-                or PyDelta_Check(self)
-                or cnp.is_timedelta64_object(self)
-            )
-        ):
-            return Interval(y.left + self, y.right + self, closed=y.closed)
         return NotImplemented
 
     def __radd__(self, other):
@@ -529,10 +518,6 @@ cdef class Interval(IntervalMixin):
     def __mul__(self, y):
         if isinstance(y, numbers.Number):
             return Interval(self.left * y, self.right * y, closed=self.closed)
-        elif isinstance(y, Interval) and isinstance(self, numbers.Number):
-            # __radd__ semantics
-            # TODO(cython3): remove this
-            return Interval(y.left * self, y.right * self, closed=y.closed)
         return NotImplemented
 
     def __rmul__(self, other):

pandas/_libs/tslibs/nattype.pyx

@@ -124,11 +124,6 @@ cdef class _NaT(datetime):
         return NotImplemented
 
     def __add__(self, other):
-        if self is not c_NaT:
-            # TODO(cython3): remove this it moved to __radd__
-            # cython __radd__ semantics
-            self, other = other, self
-
         if PyDateTime_Check(other):
             return c_NaT
         elif PyDelta_Check(other):
@@ -158,14 +153,6 @@ cdef class _NaT(datetime):
     def __sub__(self, other):
         # Duplicate some logic from _Timestamp.__sub__ to avoid needing
         # to subclass; allows us to @final(_Timestamp.__sub__)
-        cdef:
-            bint is_rsub = False
-
-        if self is not c_NaT:
-            # cython __rsub__ semantics
-            # TODO(cython3): remove __rsub__ logic from here
-            self, other = other, self
-            is_rsub = True
 
         if PyDateTime_Check(other):
             return c_NaT
@@ -180,19 +167,9 @@ cdef class _NaT(datetime):
 
         elif util.is_array(other):
             if other.dtype.kind == "m":
-                if not is_rsub:
-                    # NaT - timedelta64 we treat NaT as datetime64, so result
-                    #  is datetime64
-                    result = np.empty(other.shape, dtype="datetime64[ns]")
-                    result.fill("NaT")
-                    return result
-
-                # __rsub__ logic here
-                # TODO(cython3): remove this, move above code out of
-                # ``if not is_rsub`` block
-                # timedelta64 - NaT we have to treat NaT as timedelta64
-                # for this to be meaningful, and the result is timedelta64
-                result = np.empty(other.shape, dtype="timedelta64[ns]")
+                # NaT - timedelta64 we treat NaT as datetime64, so result
+                #  is datetime64
+                result = np.empty(other.shape, dtype="datetime64[ns]")
                 result.fill("NaT")
                 return result
 

pandas/_libs/tslibs/offsets.pyx

@@ -489,12 +489,7 @@ cdef class BaseOffset:
         return type(self)(n=1, normalize=self.normalize, **self.kwds)
 
     def __add__(self, other):
-        if not isinstance(self, BaseOffset):
-            # cython semantics; this is __radd__
-            # TODO(cython3): remove this, this moved to __radd__
-            return other.__add__(self)
-
-        elif util.is_array(other) and other.dtype == object:
+        if util.is_array(other) and other.dtype == object:
             return np.array([self + x for x in other])
 
         try:
@@ -511,10 +506,6 @@ cdef class BaseOffset:
         elif type(other) is type(self):
             return type(self)(self.n - other.n, normalize=self.normalize,
                               **self.kwds)
-        elif not isinstance(self, BaseOffset):
-            # TODO(cython3): remove, this moved to __rsub__
-            # cython semantics, this is __rsub__
-            return (-other).__add__(self)
         else:
             # e.g. PeriodIndex
             return NotImplemented
@@ -528,10 +519,6 @@ cdef class BaseOffset:
         elif is_integer_object(other):
             return type(self)(n=other * self.n, normalize=self.normalize,
                               **self.kwds)
-        elif not isinstance(self, BaseOffset):
-            # TODO(cython3): remove this, this moved to __rmul__
-            # cython semantics, this is __rmul__
-            return other.__mul__(self)
         return NotImplemented
 
     def __rmul__(self, other):
@@ -1025,10 +1012,6 @@ cdef class Tick(SingleConstructorOffset):
         return self.delta.__gt__(other)
 
     def __mul__(self, other):
-        if not isinstance(self, Tick):
-            # TODO(cython3), remove this, this moved to __rmul__
-            # cython semantics, this is __rmul__
-            return other.__mul__(self)
         if is_float_object(other):
             n = other * self.n
             # If the new `n` is an integer, we can represent it using the
@@ -1056,11 +1039,6 @@ cdef class Tick(SingleConstructorOffset):
         return _wrap_timedelta_result(result)
 
     def __add__(self, other):
-        if not isinstance(self, Tick):
-            # cython semantics; this is __radd__
-            # TODO(cython3): remove this, this moved to __radd__
-            return other.__add__(self)
-
         if isinstance(other, Tick):
             if type(self) is type(other):
                 return type(self)(self.n + other.n)

pandas/_libs/tslibs/period.pyx

@@ -1855,13 +1855,6 @@ cdef class _Period(PeriodMixin):
 
     @cython.overflowcheck(True)
     def __add__(self, other):
-        if not is_period_object(self):
-            # cython semantics; this is analogous to a call to __radd__
-            # TODO(cython3): remove this
-            if self is NaT:
-                return NaT
-            return other.__add__(self)
-
         if is_any_td_scalar(other):
             return self._add_timedeltalike_scalar(other)
         elif is_offset_object(other):
@@ -1893,14 +1886,7 @@ cdef class _Period(PeriodMixin):
         return self.__add__(other)
 
     def __sub__(self, other):
-        if not is_period_object(self):
-            # cython semantics; this is like a call to __rsub__
-            # TODO(cython3): remove this
-            if self is NaT:
-                return NaT
-            return NotImplemented
-
-        elif (
+        if (
             is_any_td_scalar(other)
             or is_offset_object(other)
             or util.is_integer_object(other)

pandas/_libs/tslibs/timestamps.pyx

@@ -475,11 +475,6 @@ cdef class _Timestamp(ABCTimestamp):
                     dtype=object,
                 )
 
-        elif not isinstance(self, _Timestamp):
-            # cython semantics, args have been switched and this is __radd__
-            # TODO(cython3): remove this it moved to __radd__
-            return other.__add__(self)
-
         return NotImplemented
 
     def __radd__(self, other):