bpo-15873: Implement [date][time].fromisoformat (#4699)
Closes bpo-15873.
diff --git a/Lib/datetime.py b/Lib/datetime.py
index 67d8600..8fa18a7 100644
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -173,6 +173,24 @@
else:
return fmt.format(hh, mm, ss, us)
+def _format_offset(off):
+ s = ''
+ if off is not None:
+ if off.days < 0:
+ sign = "-"
+ off = -off
+ else:
+ sign = "+"
+ hh, mm = divmod(off, timedelta(hours=1))
+ mm, ss = divmod(mm, timedelta(minutes=1))
+ s += "%s%02d:%02d" % (sign, hh, mm)
+ if ss or ss.microseconds:
+ s += ":%02d" % ss.seconds
+
+ if ss.microseconds:
+ s += '.%06d' % ss.microseconds
+ return s
+
# Correctly substitute for %z and %Z escapes in strftime formats.
def _wrap_strftime(object, format, timetuple):
# Don't call utcoffset() or tzname() unless actually needed.
@@ -237,6 +255,102 @@
newformat = "".join(newformat)
return _time.strftime(newformat, timetuple)
+# Helpers for parsing the result of isoformat()
+def _parse_isoformat_date(dtstr):
+ # It is assumed that this function will only be called with a
+ # string of length exactly 10, and (though this is not used) ASCII-only
+ year = int(dtstr[0:4])
+ if dtstr[4] != '-':
+ raise ValueError('Invalid date separator: %s' % dtstr[4])
+
+ month = int(dtstr[5:7])
+
+ if dtstr[7] != '-':
+ raise ValueError('Invalid date separator')
+
+ day = int(dtstr[8:10])
+
+ return [year, month, day]
+
+def _parse_hh_mm_ss_ff(tstr):
+ # Parses things of the form HH[:MM[:SS[.fff[fff]]]]
+ len_str = len(tstr)
+
+ time_comps = [0, 0, 0, 0]
+ pos = 0
+ for comp in range(0, 3):
+ if (len_str - pos) < 2:
+ raise ValueError('Incomplete time component')
+
+ time_comps[comp] = int(tstr[pos:pos+2])
+
+ pos += 2
+ next_char = tstr[pos:pos+1]
+
+ if not next_char or comp >= 2:
+ break
+
+ if next_char != ':':
+ raise ValueError('Invalid time separator: %c' % next_char)
+
+ pos += 1
+
+ if pos < len_str:
+ if tstr[pos] != '.':
+ raise ValueError('Invalid microsecond component')
+ else:
+ pos += 1
+
+ len_remainder = len_str - pos
+ if len_remainder not in (3, 6):
+ raise ValueError('Invalid microsecond component')
+
+ time_comps[3] = int(tstr[pos:])
+ if len_remainder == 3:
+ time_comps[3] *= 1000
+
+ return time_comps
+
+def _parse_isoformat_time(tstr):
+ # Format supported is HH[:MM[:SS[.fff[fff]]]][+HH:MM[:SS[.ffffff]]]
+ len_str = len(tstr)
+ if len_str < 2:
+ raise ValueError('Isoformat time too short')
+
+ # This is equivalent to re.search('[+-]', tstr), but faster
+ tz_pos = (tstr.find('-') + 1 or tstr.find('+') + 1)
+ timestr = tstr[:tz_pos-1] if tz_pos > 0 else tstr
+
+ time_comps = _parse_hh_mm_ss_ff(timestr)
+
+ tzi = None
+ if tz_pos > 0:
+ tzstr = tstr[tz_pos:]
+
+ # Valid time zone strings are:
+ # HH:MM len: 5
+ # HH:MM:SS len: 8
+ # HH:MM:SS.ffffff len: 15
+
+ if len(tzstr) not in (5, 8, 15):
+ raise ValueError('Malformed time zone string')
+
+ tz_comps = _parse_hh_mm_ss_ff(tzstr)
+ if all(x == 0 for x in tz_comps):
+ tzi = timezone.utc
+ else:
+ tzsign = -1 if tstr[tz_pos - 1] == '-' else 1
+
+ td = timedelta(hours=tz_comps[0], minutes=tz_comps[1],
+ seconds=tz_comps[2], microseconds=tz_comps[3])
+
+ tzi = timezone(tzsign * td)
+
+ time_comps.append(tzi)
+
+ return time_comps
+
+
# Just raise TypeError if the arg isn't None or a string.
def _check_tzname(name):
if name is not None and not isinstance(name, str):
@@ -732,6 +846,19 @@
y, m, d = _ord2ymd(n)
return cls(y, m, d)
+ @classmethod
+ def fromisoformat(cls, date_string):
+ """Construct a date from the output of date.isoformat()."""
+ if not isinstance(date_string, str):
+ raise TypeError('fromisoformat: argument must be str')
+
+ try:
+ assert len(date_string) == 10
+ return cls(*_parse_isoformat_date(date_string))
+ except Exception:
+ raise ValueError('Invalid isoformat string: %s' % date_string)
+
+
# Conversions to string
def __repr__(self):
@@ -1190,22 +1317,10 @@
# Conversion to string
- def _tzstr(self, sep=":"):
- """Return formatted timezone offset (+xx:xx) or None."""
+ def _tzstr(self):
+ """Return formatted timezone offset (+xx:xx) or an empty string."""
off = self.utcoffset()
- if off is not None:
- if off.days < 0:
- sign = "-"
- off = -off
- else:
- sign = "+"
- hh, mm = divmod(off, timedelta(hours=1))
- mm, ss = divmod(mm, timedelta(minutes=1))
- assert 0 <= hh < 24
- off = "%s%02d%s%02d" % (sign, hh, sep, mm)
- if ss:
- off += ':%02d' % ss.seconds
- return off
+ return _format_offset(off)
def __repr__(self):
"""Convert to formal string, for repr()."""
@@ -1244,6 +1359,18 @@
__str__ = isoformat
+ @classmethod
+ def fromisoformat(cls, time_string):
+ """Construct a time from the output of isoformat()."""
+ if not isinstance(time_string, str):
+ raise TypeError('fromisoformat: argument must be str')
+
+ try:
+ return cls(*_parse_isoformat_time(time_string))
+ except Exception:
+ raise ValueError('Invalid isoformat string: %s' % time_string)
+
+
def strftime(self, fmt):
"""Format using strftime(). The date part of the timestamp passed
to underlying strftime should not be used.
@@ -1497,6 +1624,31 @@
time.hour, time.minute, time.second, time.microsecond,
tzinfo, fold=time.fold)
+ @classmethod
+ def fromisoformat(cls, date_string):
+ """Construct a datetime from the output of datetime.isoformat()."""
+ if not isinstance(date_string, str):
+ raise TypeError('fromisoformat: argument must be str')
+
+ # Split this at the separator
+ dstr = date_string[0:10]
+ tstr = date_string[11:]
+
+ try:
+ date_components = _parse_isoformat_date(dstr)
+ except ValueError:
+ raise ValueError('Invalid isoformat string: %s' % date_string)
+
+ if tstr:
+ try:
+ time_components = _parse_isoformat_time(tstr)
+ except ValueError:
+ raise ValueError('Invalid isoformat string: %s' % date_string)
+ else:
+ time_components = [0, 0, 0, 0, None]
+
+ return cls(*(date_components + time_components))
+
def timetuple(self):
"Return local time tuple compatible with time.localtime()."
dst = self.dst()
@@ -1673,18 +1825,10 @@
self._microsecond, timespec))
off = self.utcoffset()
- if off is not None:
- if off.days < 0:
- sign = "-"
- off = -off
- else:
- sign = "+"
- hh, mm = divmod(off, timedelta(hours=1))
- mm, ss = divmod(mm, timedelta(minutes=1))
- s += "%s%02d:%02d" % (sign, hh, mm)
- if ss:
- assert not ss.microseconds
- s += ":%02d" % ss.seconds
+ tz = _format_offset(off)
+ if tz:
+ s += tz
+
return s
def __repr__(self):
@@ -2275,9 +2419,10 @@
_check_date_fields, _check_int_field, _check_time_fields,
_check_tzinfo_arg, _check_tzname, _check_utc_offset, _cmp, _cmperror,
_date_class, _days_before_month, _days_before_year, _days_in_month,
- _format_time, _is_leap, _isoweek1monday, _math, _ord2ymd,
- _time, _time_class, _tzinfo_class, _wrap_strftime, _ymd2ord,
- _divide_and_round)
+ _format_time, _format_offset, _is_leap, _isoweek1monday, _math,
+ _ord2ymd, _time, _time_class, _tzinfo_class, _wrap_strftime, _ymd2ord,
+ _divide_and_round, _parse_isoformat_date, _parse_isoformat_time,
+ _parse_hh_mm_ss_ff)
# XXX Since import * above excludes names that start with _,
# docstring does not get overwritten. In the future, it may be
# appropriate to maintain a single module level docstring and