base.py 文件源码

def _sqlite_format_dtdelta(conn, lhs, rhs):
    """
    LHS and RHS can be either:
        - An integer number of microseconds
        - A string representing a timedelta object
        - A string representing a datetime
    """
    try:
        if isinstance(lhs, six.integer_types):
            lhs = str(decimal.Decimal(lhs) / decimal.Decimal(1000000))
        real_lhs = parse_duration(lhs)
        if real_lhs is None:
            real_lhs = backend_utils.typecast_timestamp(lhs)
        if isinstance(rhs, six.integer_types):
            rhs = str(decimal.Decimal(rhs) / decimal.Decimal(1000000))
        real_rhs = parse_duration(rhs)
        if real_rhs is None:
            real_rhs = backend_utils.typecast_timestamp(rhs)
        if conn.strip() == '+':
            out = real_lhs + real_rhs
        else:
            out = real_lhs - real_rhs
    except (ValueError, TypeError):
        return None
    # typecast_timestamp returns a date or a datetime without timezone.
    # It will be formatted as "%Y-%m-%d" or "%Y-%m-%d %H:%M:%S[.%f]"
    return str(out)