def _parsed_string_to_bounds(self, reso: str, parsed: datetime):
"""
Calculate datetime bounds for parsed time string and its resolution.
Parameters
----------
reso : str
Resolution provided by parsed string.
parsed : datetime
Datetime from parsed string.
Returns
-------
lower, upper: pd.Timestamp
"""
valid_resos = {
"year",
"month",
"quarter",
"day",
"hour",
"minute",
"second",
"minute",
"second",
"microsecond",
}
if reso not in valid_resos:
raise KeyError
grp = Resolution.get_freq_group(reso)
per = Period(parsed, freq=(grp, 1))
start, end = per.start_time, per.end_time
# GH 24076
# If an incoming date string contained a UTC offset, need to localize
# the parsed date to this offset first before aligning with the index's
# timezone
if parsed.tzinfo is not None:
if self.tz is None:
raise ValueError(
"The index must be timezone aware when indexing "
"with a date string with a UTC offset"
)
start = start.tz_localize(parsed.tzinfo).tz_convert(self.tz)
end = end.tz_localize(parsed.tzinfo).tz_convert(self.tz)
elif self.tz is not None:
start = start.tz_localize(self.tz)
end = end.tz_localize(self.tz)
return start, end
