[Python-checkins] cpython: Closes issue #12006: Add ISO 8601 year, week, and day directives to strptime.
alexander.belopolsky
python-checkins at python.org
Tue Oct 6 13:30:04 EDT 2015
https://hg.python.org/cpython/rev/acdebfbfbdcf
changeset: 98564:acdebfbfbdcf
user: Alexander Belopolsky <alexander.belopolsky at gmail.com>
date: Tue Oct 06 13:29:56 2015 -0400
summary:
Closes issue #12006: Add ISO 8601 year, week, and day directives to strptime.
This commit adds %G, %V, and %u directives to strptime. Thanks Ashley Anderson
for the implementation.
files:
Doc/library/datetime.rst | 37 ++++++++++++-
Doc/whatsnew/3.6.rst | 8 ++
Lib/_strptime.py | 81 ++++++++++++++++++++++----
Lib/test/test_strptime.py | 57 ++++++++++++++----
Misc/NEWS | 3 +
5 files changed, 159 insertions(+), 27 deletions(-)
diff --git a/Doc/library/datetime.rst b/Doc/library/datetime.rst
--- a/Doc/library/datetime.rst
+++ b/Doc/library/datetime.rst
@@ -1909,6 +1909,34 @@
| ``%%`` | A literal ``'%'`` character. | % | |
+-----------+--------------------------------+------------------------+-------+
+Several additional directives not required by the C89 standard are included for
+convenience. These parameters all correspond to ISO 8601 date values. These
+may not be available on all platforms when used with the :meth:`strftime`
+method. The ISO 8601 year and ISO 8601 week directives are not interchangeable
+with the year and week number directives above. Calling :meth:`strptime` with
+incomplete or ambiguous ISO 8601 directives will raise a :exc:`ValueError`.
+
++-----------+--------------------------------+------------------------+-------+
+| Directive | Meaning | Example | Notes |
++===========+================================+========================+=======+
+| ``%G`` | ISO 8601 year with century | 0001, 0002, ..., 2013, | \(8) |
+| | representing the year that | 2014, ..., 9998, 9999 | |
+| | contains the greater part of | | |
+| | the ISO week (``%V``). | | |
++-----------+--------------------------------+------------------------+-------+
+| ``%u`` | ISO 8601 weekday as a decimal | 1, 2, ..., 7 | |
+| | number where 1 is Monday. | | |
++-----------+--------------------------------+------------------------+-------+
+| ``%V`` | ISO 8601 week as a decimal | 01, 02, ..., 53 | \(8) |
+| | number with Monday as | | |
+| | the first day of the week. | | |
+| | Week 01 is the week containing | | |
+| | Jan 4. | | |
++-----------+--------------------------------+------------------------+-------+
+
+.. versionadded:: 3.6
+ ``%G``, ``%u`` and ``%V`` were added.
+
Notes:
(1)
@@ -1973,7 +2001,14 @@
(7)
When used with the :meth:`strptime` method, ``%U`` and ``%W`` are only used
- in calculations when the day of the week and the year are specified.
+ in calculations when the day of the week and the calendar year (``%Y``)
+ are specified.
+
+(8)
+ Similar to ``%U`` and ``%W``, ``%V`` is only used in calculations when the
+ day of the week and the ISO year (``%G``) are specified in a
+ :meth:`strptime` format string. Also note that ``%G`` and ``%Y`` are not
+ interchangable.
.. rubric:: Footnotes
diff --git a/Doc/whatsnew/3.6.rst b/Doc/whatsnew/3.6.rst
--- a/Doc/whatsnew/3.6.rst
+++ b/Doc/whatsnew/3.6.rst
@@ -110,6 +110,14 @@
with underscores. A space or a colon can be added after completed keyword.
(Contributed by Serhiy Storchaka in :issue:`25011` and :issue:`25209`.)
+datetime
+--------
+
+* :meth:`datetime.stftime <datetime.datetime.stftime>` and
+ :meth:`date.stftime <datetime.date.stftime>` methods now support ISO 8601
+ date directives ``%G``, ``%u`` and ``%V``.
+ (Contributed by Ashley Anderson in :issue:`12006`.)
+
Optimizations
=============
diff --git a/Lib/_strptime.py b/Lib/_strptime.py
--- a/Lib/_strptime.py
+++ b/Lib/_strptime.py
@@ -195,12 +195,15 @@
'f': r"(?P<f>[0-9]{1,6})",
'H': r"(?P<H>2[0-3]|[0-1]\d|\d)",
'I': r"(?P<I>1[0-2]|0[1-9]|[1-9])",
+ 'G': r"(?P<G>\d\d\d\d)",
'j': r"(?P<j>36[0-6]|3[0-5]\d|[1-2]\d\d|0[1-9]\d|00[1-9]|[1-9]\d|0[1-9]|[1-9])",
'm': r"(?P<m>1[0-2]|0[1-9]|[1-9])",
'M': r"(?P<M>[0-5]\d|\d)",
'S': r"(?P<S>6[0-1]|[0-5]\d|\d)",
'U': r"(?P<U>5[0-3]|[0-4]\d|\d)",
'w': r"(?P<w>[0-6])",
+ 'u': r"(?P<u>[1-7])",
+ 'V': r"(?P<V>5[0-3]|0[1-9]|[1-4]\d|\d)",
# W is set below by using 'U'
'y': r"(?P<y>\d\d)",
#XXX: Does 'Y' need to worry about having less or more than
@@ -295,6 +298,22 @@
return 1 + days_to_week + day_of_week
+def _calc_julian_from_V(iso_year, iso_week, iso_weekday):
+ """Calculate the Julian day based on the ISO 8601 year, week, and weekday.
+ ISO weeks start on Mondays, with week 01 being the week containing 4 Jan.
+ ISO week days range from 1 (Monday) to 7 (Sunday).
+ """
+ correction = datetime_date(iso_year, 1, 4).isoweekday() + 3
+ ordinal = (iso_week * 7) + iso_weekday - correction
+ # ordinal may be negative or 0 now, which means the date is in the previous
+ # calendar year
+ if ordinal < 1:
+ ordinal += datetime_date(iso_year, 1, 1).toordinal()
+ iso_year -= 1
+ ordinal -= datetime_date(iso_year, 1, 1).toordinal()
+ return iso_year, ordinal
+
+
def _strptime(data_string, format="%a %b %d %H:%M:%S %Y"):
"""Return a 2-tuple consisting of a time struct and an int containing
the number of microseconds based on the input string and the
@@ -339,15 +358,15 @@
raise ValueError("unconverted data remains: %s" %
data_string[found.end():])
- year = None
+ iso_year = year = None
month = day = 1
hour = minute = second = fraction = 0
tz = -1
tzoffset = None
# Default to -1 to signify that values not known; not critical to have,
# though
- week_of_year = -1
- week_of_year_start = -1
+ iso_week = week_of_year = None
+ week_of_year_start = None
# weekday and julian defaulted to None so as to signal need to calculate
# values
weekday = julian = None
@@ -369,6 +388,8 @@
year += 1900
elif group_key == 'Y':
year = int(found_dict['Y'])
+ elif group_key == 'G':
+ iso_year = int(found_dict['G'])
elif group_key == 'm':
month = int(found_dict['m'])
elif group_key == 'B':
@@ -414,6 +435,9 @@
weekday = 6
else:
weekday -= 1
+ elif group_key == 'u':
+ weekday = int(found_dict['u'])
+ weekday -= 1
elif group_key == 'j':
julian = int(found_dict['j'])
elif group_key in ('U', 'W'):
@@ -424,6 +448,8 @@
else:
# W starts week on Monday.
week_of_year_start = 0
+ elif group_key == 'V':
+ iso_week = int(found_dict['V'])
elif group_key == 'z':
z = found_dict['z']
tzoffset = int(z[1:3]) * 60 + int(z[3:5])
@@ -444,28 +470,57 @@
else:
tz = value
break
+ # Deal with the cases where ambiguities arize
+ # don't assume default values for ISO week/year
+ if year is None and iso_year is not None:
+ if iso_week is None or weekday is None:
+ raise ValueError("ISO year directive '%G' must be used with "
+ "the ISO week directive '%V' and a weekday "
+ "directive ('%A', '%a', '%w', or '%u').")
+ if julian is not None:
+ raise ValueError("Day of the year directive '%j' is not "
+ "compatible with ISO year directive '%G'. "
+ "Use '%Y' instead.")
+ elif week_of_year is None and iso_week is not None:
+ if weekday is None:
+ raise ValueError("ISO week directive '%V' must be used with "
+ "the ISO year directive '%G' and a weekday "
+ "directive ('%A', '%a', '%w', or '%u').")
+ else:
+ raise ValueError("ISO week directive '%V' is incompatible with "
+ "the year directive '%Y'. Use the ISO year '%G' "
+ "instead.")
+
leap_year_fix = False
if year is None and month == 2 and day == 29:
year = 1904 # 1904 is first leap year of 20th century
leap_year_fix = True
elif year is None:
year = 1900
+
+
# If we know the week of the year and what day of that week, we can figure
# out the Julian day of the year.
- if julian is None and week_of_year != -1 and weekday is not None:
- week_starts_Mon = True if week_of_year_start == 0 else False
- julian = _calc_julian_from_U_or_W(year, week_of_year, weekday,
- week_starts_Mon)
- # Cannot pre-calculate datetime_date() since can change in Julian
- # calculation and thus could have different value for the day of the week
- # calculation.
+ if julian is None and weekday is not None:
+ if week_of_year is not None:
+ week_starts_Mon = True if week_of_year_start == 0 else False
+ julian = _calc_julian_from_U_or_W(year, week_of_year, weekday,
+ week_starts_Mon)
+ elif iso_year is not None and iso_week is not None:
+ year, julian = _calc_julian_from_V(iso_year, iso_week, weekday + 1)
+
if julian is None:
+ # Cannot pre-calculate datetime_date() since can change in Julian
+ # calculation and thus could have different value for the day of
+ # the week calculation.
# Need to add 1 to result since first day of the year is 1, not 0.
julian = datetime_date(year, month, day).toordinal() - \
datetime_date(year, 1, 1).toordinal() + 1
- else: # Assume that if they bothered to include Julian day it will
- # be accurate.
- datetime_result = datetime_date.fromordinal((julian - 1) + datetime_date(year, 1, 1).toordinal())
+ else: # Assume that if they bothered to include Julian day (or if it was
+ # calculated above with year/week/weekday) it will be accurate.
+ datetime_result = datetime_date.fromordinal(
+ (julian - 1) +
+ datetime_date(year, 1, 1).toordinal())
year = datetime_result.year
month = datetime_result.month
day = datetime_result.day
diff --git a/Lib/test/test_strptime.py b/Lib/test/test_strptime.py
--- a/Lib/test/test_strptime.py
+++ b/Lib/test/test_strptime.py
@@ -152,8 +152,8 @@
"'%s' using '%s'; group 'a' = '%s', group 'b' = %s'" %
(found.string, found.re.pattern, found.group('a'),
found.group('b')))
- for directive in ('a','A','b','B','c','d','H','I','j','m','M','p','S',
- 'U','w','W','x','X','y','Y','Z','%'):
+ for directive in ('a','A','b','B','c','d','G','H','I','j','m','M','p',
+ 'S','u','U','V','w','W','x','X','y','Y','Z','%'):
compiled = self.time_re.compile("%" + directive)
found = compiled.match(time.strftime("%" + directive))
self.assertTrue(found, "Matching failed on '%s' using '%s' regex" %
@@ -218,6 +218,26 @@
else:
self.fail("'%s' did not raise ValueError" % bad_format)
+ # Ambiguous or incomplete cases using ISO year/week/weekday directives
+ # 1. ISO week (%V) is specified, but the year is specified with %Y
+ # instead of %G
+ with self.assertRaises(ValueError):
+ _strptime._strptime("1999 50", "%Y %V")
+ # 2. ISO year (%G) and ISO week (%V) are specified, but weekday is not
+ with self.assertRaises(ValueError):
+ _strptime._strptime("1999 51", "%G %V")
+ # 3. ISO year (%G) and weekday are specified, but ISO week (%V) is not
+ for w in ('A', 'a', 'w', 'u'):
+ with self.assertRaises(ValueError):
+ _strptime._strptime("1999 51","%G %{}".format(w))
+ # 4. ISO year is specified alone (e.g. time.strptime('2015', '%G'))
+ with self.assertRaises(ValueError):
+ _strptime._strptime("2015", "%G")
+ # 5. Julian/ordinal day (%j) is specified with %G, but not %Y
+ with self.assertRaises(ValueError):
+ _strptime._strptime("1999 256", "%G %j")
+
+
def test_strptime_exception_context(self):
# check that this doesn't chain exceptions needlessly (see #17572)
with self.assertRaises(ValueError) as e:
@@ -289,7 +309,7 @@
def test_weekday(self):
# Test weekday directives
- for directive in ('A', 'a', 'w'):
+ for directive in ('A', 'a', 'w', 'u'):
self.helper(directive,6)
def test_julian(self):
@@ -458,16 +478,20 @@
# Should be able to infer date if given year, week of year (%U or %W)
# and day of the week
def test_helper(ymd_tuple, test_reason):
- for directive in ('W', 'U'):
- format_string = "%%Y %%%s %%w" % directive
- dt_date = datetime_date(*ymd_tuple)
- strp_input = dt_date.strftime(format_string)
- strp_output = _strptime._strptime_time(strp_input, format_string)
- self.assertTrue(strp_output[:3] == ymd_tuple,
- "%s(%s) test failed w/ '%s': %s != %s (%s != %s)" %
- (test_reason, directive, strp_input,
- strp_output[:3], ymd_tuple,
- strp_output[7], dt_date.timetuple()[7]))
+ for year_week_format in ('%Y %W', '%Y %U', '%G %V'):
+ for weekday_format in ('%w', '%u', '%a', '%A'):
+ format_string = year_week_format + ' ' + weekday_format
+ with self.subTest(test_reason,
+ date=ymd_tuple,
+ format=format_string):
+ dt_date = datetime_date(*ymd_tuple)
+ strp_input = dt_date.strftime(format_string)
+ strp_output = _strptime._strptime_time(strp_input,
+ format_string)
+ msg = "%r: %s != %s" % (strp_input,
+ strp_output[7],
+ dt_date.timetuple()[7])
+ self.assertEqual(strp_output[:3], ymd_tuple, msg)
test_helper((1901, 1, 3), "week 0")
test_helper((1901, 1, 8), "common case")
test_helper((1901, 1, 13), "day on Sunday")
@@ -499,18 +523,25 @@
self.assertEqual(_strptime._strptime_time(value, format)[:-1], expected)
check('2015 0 0', '%Y %U %w', 2014, 12, 28, 0, 0, 0, 6, -3)
check('2015 0 0', '%Y %W %w', 2015, 1, 4, 0, 0, 0, 6, 4)
+ check('2015 1 1', '%G %V %u', 2014, 12, 29, 0, 0, 0, 0, 363)
check('2015 0 1', '%Y %U %w', 2014, 12, 29, 0, 0, 0, 0, -2)
check('2015 0 1', '%Y %W %w', 2014, 12, 29, 0, 0, 0, 0, -2)
+ check('2015 1 2', '%G %V %u', 2014, 12, 30, 0, 0, 0, 1, 364)
check('2015 0 2', '%Y %U %w', 2014, 12, 30, 0, 0, 0, 1, -1)
check('2015 0 2', '%Y %W %w', 2014, 12, 30, 0, 0, 0, 1, -1)
+ check('2015 1 3', '%G %V %u', 2014, 12, 31, 0, 0, 0, 2, 365)
check('2015 0 3', '%Y %U %w', 2014, 12, 31, 0, 0, 0, 2, 0)
check('2015 0 3', '%Y %W %w', 2014, 12, 31, 0, 0, 0, 2, 0)
+ check('2015 1 4', '%G %V %u', 2015, 1, 1, 0, 0, 0, 3, 1)
check('2015 0 4', '%Y %U %w', 2015, 1, 1, 0, 0, 0, 3, 1)
check('2015 0 4', '%Y %W %w', 2015, 1, 1, 0, 0, 0, 3, 1)
+ check('2015 1 5', '%G %V %u', 2015, 1, 2, 0, 0, 0, 4, 2)
check('2015 0 5', '%Y %U %w', 2015, 1, 2, 0, 0, 0, 4, 2)
check('2015 0 5', '%Y %W %w', 2015, 1, 2, 0, 0, 0, 4, 2)
+ check('2015 1 6', '%G %V %u', 2015, 1, 3, 0, 0, 0, 5, 3)
check('2015 0 6', '%Y %U %w', 2015, 1, 3, 0, 0, 0, 5, 3)
check('2015 0 6', '%Y %W %w', 2015, 1, 3, 0, 0, 0, 5, 3)
+ check('2015 1 7', '%G %V %u', 2015, 1, 4, 0, 0, 0, 6, 4)
class CacheTests(unittest.TestCase):
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -383,6 +383,9 @@
- Issue #23572: Fixed functools.singledispatch on classes with falsy
metaclasses. Patch by Ethan Furman.
+- Issue #12006: Add ISO 8601 year, week, and day directives (%G, %V, %u) to
+ strptime.
+
Documentation
-------------
--
Repository URL: https://hg.python.org/cpython
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