Function _parse_tz_str

Lib/zoneinfo/_zoneinfo.py:627–702

(tz_str)

def _parse_tz_str(tz_str):
    # The tz string has the format:
    #
    # std[offset[dst[offset],start[/time],end[/time]]]
    #
    # std and dst must be 3 or more characters long and must not contain
    # a leading colon, embedded digits, commas, nor a plus or minus signs;
    # The spaces between "std" and "offset" are only for display and are
    # not actually present in the string.
    #
    # The format of the offset is ``[+|-]hh[:mm[:ss]]``

    offset_str, *start_end_str = tz_str.split(",", 1)

    parser_re = re.compile(
        r"""
        (?P<std>[^<0-9:.+-]+|<[a-zA-Z0-9+-]+>)
        (?:
            (?P<stdoff>[+-]?\d{1,3}(?::\d{2}(?::\d{2})?)?)
            (?:
                (?P<dst>[^0-9:.+-]+|<[a-zA-Z0-9+-]+>)
                (?P<dstoff>[+-]?\d{1,3}(?::\d{2}(?::\d{2})?)?)?
            )? # dst
        )? # stdoff
        """,
        re.ASCII|re.VERBOSE
    )

    m = parser_re.fullmatch(offset_str)

    if m is None:
        raise ValueError(f"{tz_str} is not a valid TZ string")

    std_abbr = m.group("std")
    dst_abbr = m.group("dst")
    dst_offset = None

    std_abbr = std_abbr.strip("<>")

    if dst_abbr:
        dst_abbr = dst_abbr.strip("<>")

    if std_offset := m.group("stdoff"):
        try:
            std_offset = _parse_tz_delta(std_offset)
        except ValueError as e:
            raise ValueError(f"Invalid STD offset in {tz_str}") from e
    else:
        std_offset = 0

    if dst_abbr is not None:
        if dst_offset := m.group("dstoff"):
            try:
                dst_offset = _parse_tz_delta(dst_offset)
            except ValueError as e:
                raise ValueError(f"Invalid DST offset in {tz_str}") from e
        else:
            dst_offset = std_offset + 3600