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Extended time elements with copy from RFC 822 and 1123 methods log2ti…
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…meline#162
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@joachimmetz
joachimmetz committed Jun 13, 2020
1 parent c3510c1 commit 581b7fb
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356 changes: 353 additions & 3 deletions dfdatetime/time_elements.py
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,61 @@ class TimeElements(interface.DateTimeValues):
is_local_time (bool): True if the date and time value is in local time.
"""

# Maps the RFC 822, RFC 1123 and RFC 2822 defintions to their corresponding
# integer values.
_RFC_MONTH_MAPPINGS = {
'Jan': 1,
'Feb': 2,
'Mar': 3,
'Apr': 4,
'May': 5,
'Jun': 6,
'Jul': 7,
'Aug': 8,
'Sep': 9,
'Oct': 10,
'Nov': 11,
'Dec': 12}

_RFC_TIME_ZONE_MAPPINGS = {
'UT': 0,
'GMT': 0,
'EST': -5,
'EDT': -4,
'CST': -6,
'CDT': -5,
'MST': -7,
'MDT': -6,
'PST': -8,
'PDT': -7,
'A': -1,
'B': -2,
'C': -3,
'D': -4,
'E': -5,
'F': -6,
'G': -7,
'H': -8,
'I': -9,
'K': -10,
'L': -11,
'M': -12,
'N': 1,
'O': 2,
'P': 3,
'Q': 4,
'R': 5,
'S': 6,
'T': 7,
'U': 8,
'V': 9,
'W': 10,
'X': 11,
'Y': 12,
'Z': 0}

_RFC_WEEKDAYS = frozenset(['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun'])

def __init__(self, time_elements_tuple=None):
"""Initializes time elements.
Expand Down Expand Up @@ -97,8 +152,7 @@ def _CopyDateTimeFromStringISO8601(self, time_string):
# If a time of day is specified the time string it should at least
# contain 'YYYY-MM-DDThh'.
if time_string[10] != 'T':
raise ValueError(
'Invalid time string - missing as date and time separator.')
raise ValueError('Invalid time string - missing date and time separator.')

hours, minutes, seconds, microseconds, time_zone_offset = (
self._CopyTimeFromStringISO8601(time_string[11:]))
Expand All @@ -118,6 +172,168 @@ def _CopyDateTimeFromStringISO8601(self, time_string):

return date_time_values

def _CopyDateTimeFromStringRFC822(self, time_string):
"""Copies a date and time from a RFC 822 date and time string.
Args:
time_string (str): date and time value formatted as:
DAY, D MONTH YY hh:mm:ss ZONE
Where weekday (DAY) and seconds (ss) are optional and day of
month (D) can consist of 1 or 2 digits.
Returns:
dict[str, int]: date and time values, such as year, month, day of month,
hours, minutes, seconds, time zone offset in minutes.
Raises:
ValueError: if the time string is invalid or not supported.
"""
if not time_string:
raise ValueError('Invalid time string.')

string_segments = time_string.split(' ')

if len(string_segments) not in (5, 6):
raise ValueError('Unsupported number of time string segments.')

weekday_string = string_segments[0]
if weekday_string.endswith(','):
weekday_string = weekday_string[:-1]
if weekday_string not in self._RFC_WEEKDAYS:
raise ValueError('Invalid weekday: {0:s}.'.format(weekday_string))

string_segments.pop(0)

day_of_month_string = string_segments[0]

day_of_month = 0
if len(day_of_month_string) in (1, 2):
try:
day_of_month = int(day_of_month_string, 10)
except ValueError:
pass

if day_of_month == 0:
raise ValueError('Invalid day of month: {0:s}.'.format(
day_of_month_string))

month_string = string_segments[1]

month = self._RFC_MONTH_MAPPINGS.get(month_string)
if not month:
raise ValueError('Invalid month: {0:s}.'.format(month_string))

year_string = string_segments[2]

year = None
if len(year_string) == 2:
try:
year = int(year_string, 10)
except ValueError:
pass

if year is None:
raise ValueError('Invalid year: {0:s}.'.format(year_string))

year += 1900

hours, minutes, seconds, time_zone_offset = self._CopyTimeFromStringRFC(
string_segments[3], string_segments[4])

date_time_values = {
'year': year,
'month': month,
'day_of_month': day_of_month,
'hours': hours,
'minutes': minutes,
'time_zone_offset': time_zone_offset}

if seconds is not None:
date_time_values['seconds'] = seconds

return date_time_values

def _CopyDateTimeFromStringRFC1123(self, time_string):
"""Copies a date and time from a RFC 1123 date and time string.
Args:
time_string (str): date and time value formatted as:
DAY, D MONTH YYYY hh:mm:ss ZONE
Where weekday (DAY) and seconds (ss) are optional and day of
month (D) can consist of 1 or 2 digits.
Returns:
dict[str, int]: date and time values, such as year, month, day of month,
hours, minutes, seconds, time zone offset in minutes.
Raises:
ValueError: if the time string is invalid or not supported.
"""
if not time_string:
raise ValueError('Invalid time string.')

string_segments = time_string.split(' ')

if len(string_segments) not in (5, 6):
raise ValueError('Unsupported number of time string segments.')

weekday_string = string_segments[0]
if weekday_string.endswith(','):
weekday_string = weekday_string[:-1]
if weekday_string not in self._RFC_WEEKDAYS:
raise ValueError('Invalid weekday: {0:s}.'.format(weekday_string))

string_segments.pop(0)

day_of_month_string = string_segments[0]

day_of_month = 0
if len(day_of_month_string) in (1, 2):
try:
day_of_month = int(day_of_month_string, 10)
except ValueError:
pass

if day_of_month == 0:
raise ValueError('Invalid day of month: {0:s}.'.format(
day_of_month_string))

month_string = string_segments[1]

month = self._RFC_MONTH_MAPPINGS.get(month_string)
if not month:
raise ValueError('Invalid month: {0:s}.'.format(month_string))

year_string = string_segments[2]

year = None
if len(year_string) == 4:
try:
year = int(year_string, 10)
except ValueError:
pass

if year is None:
raise ValueError('Invalid year: {0:s}.'.format(year_string))

hours, minutes, seconds, time_zone_offset = self._CopyTimeFromStringRFC(
string_segments[3], string_segments[4])

date_time_values = {
'year': year,
'month': month,
'day_of_month': day_of_month,
'hours': hours,
'minutes': minutes,
'time_zone_offset': time_zone_offset}

if seconds is not None:
date_time_values['seconds'] = seconds

return date_time_values

def _CopyFromDateTimeValues(self, date_time_values):
"""Copies time elements from date and time values.
Expand All @@ -142,7 +358,7 @@ def _CopyFromDateTimeValues(self, date_time_values):
self._time_zone_offset = time_zone_offset

def _CopyTimeFromStringISO8601(self, time_string):
"""Copies a time from an ISO 8601 date and time string.
"""Copies a time from an ISO 8601 time string.
Args:
time_string (str): time value formatted as:
Expand Down Expand Up @@ -296,6 +512,106 @@ def _CopyTimeFromStringISO8601(self, time_string):

return hours, minutes, seconds, microseconds, time_zone_offset

def _CopyTimeFromStringRFC(self, time_string, time_zone_string):
"""Copies a time from a RFC 822, RFC 1123 or RFC 2822 time string.
Args:
time_string (str): time value formatted as: hh:mm[:ss], where seconds (ss)
are optional.
time_zone_string (str): time zone value formatted as predefined time zone
indicator or [+-]HHMM
Returns:
tuple[int, int, int, int]: hours, minutes, seconds, time zone offset in
minutes.
Raises:
ValueError: if the time string is invalid or not supported.
"""
time_string_length = len(time_string)

# The time string should at least contain 'hh:mm'.
if time_string_length < 5:
raise ValueError('Time string too short.')

if time_string_length > 8:
raise ValueError('Time string too long.')

if time_string[2] != ':':
raise ValueError('Invalid hours and minutes separator.')

try:
hours = int(time_string[0:2], 10)
except ValueError:
raise ValueError('Unable to parse hours.')

if hours not in range(0, 24):
raise ValueError('Hours value: {0:d} out of bounds.'.format(hours))

try:
minutes = int(time_string[3:5], 10)
except ValueError:
raise ValueError('Unable to parse minutes.')

if minutes not in range(0, 60):
raise ValueError('Minutes value: {0:d} out of bounds.'.format(minutes))

seconds = None

if time_string_length > 5:
if time_string_length < 8:
raise ValueError('Time string too short.')

if time_string[5] != ':':
raise ValueError('Invalid minutes and seconds separator.')

try:
seconds = int(time_string[6:8], 10)
except ValueError:
raise ValueError('Unable to parse seconds.')

if seconds not in range(0, 60):
raise ValueError('Seconds value: {0:d} out of bounds.'.format(seconds))

if time_string_length < 5:
raise ValueError('Time string too short.')

time_zone_string_length = len(time_zone_string)
if time_zone_string_length > 5:
raise ValueError('Time zone string too long.')

if time_zone_string_length < 5:
hours_from_utc = self._RFC_TIME_ZONE_MAPPINGS.get(time_zone_string, None)
minutes_from_utc = 0
if hours_from_utc is None:
raise ValueError('Invalid time zone: {0:s}.'.format(time_zone_string))

else:
if time_zone_string[0] not in ('+', '-'):
raise ValueError('Invalid time zone: {0:s}.'.format(time_zone_string))

try:
hours_from_utc = int(time_zone_string[1:3], 10)
except ValueError:
raise ValueError('Unable to parse time zone hours offset.')

if hours_from_utc not in range(0, 15):
raise ValueError('Time zone hours offset value out of bounds.')

try:
minutes_from_utc = int(time_zone_string[3:5], 10)
except ValueError:
raise ValueError('Unable to parse time zone minutes offset.')

if minutes_from_utc not in range(0, 60):
raise ValueError('Time zone minutes offset value out of bounds.')

time_zone_offset = (hours_from_utc * 60) + minutes_from_utc
if time_zone_string[0] == '-':
time_zone_offset = -time_zone_offset

return hours, minutes, seconds, time_zone_offset

def CopyFromDateTimeString(self, time_string):
"""Copies time elements from a date and time string.
Expand Down Expand Up @@ -338,6 +654,40 @@ def CopyFromStringISO8601(self, time_string):

self._CopyFromDateTimeValues(date_time_values)

def CopyFromStringRFC822(self, time_string):
"""Copies time elements from a RFC 822 date and time string.
Args:
time_string (str): date and time value formatted as:
DAY, D MONTH YY hh:mm:ss ZONE
Where weekday (DAY) and seconds (ss) are optional and day of
month (D) can consist of 1 or 2 digits.
Raises:
ValueError: if the time string is invalid or not supported.
"""
date_time_values = self._CopyDateTimeFromStringRFC822(time_string)

self._CopyFromDateTimeValues(date_time_values)

def CopyFromStringRFC1123(self, time_string):
"""Copies time elements from a RFC 1123 date and time string.
Args:
time_string (str): date and time value formatted as:
DAY, D MONTH YYYY hh:mm:ss ZONE
Where weekday (DAY) and seconds (ss) are optional and day of
month (D) can consist of 1 or 2 digits.
Raises:
ValueError: if the time string is invalid or not supported.
"""
date_time_values = self._CopyDateTimeFromStringRFC1123(time_string)

self._CopyFromDateTimeValues(date_time_values)

def CopyFromStringTuple(self, time_elements_tuple):
"""Copies time elements from string-based time elements tuple.
Expand Down
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