Added fromisoformat() to date and datetime

adafruit_datetime.py

@@ -29,6 +29,7 @@
 # pylint: disable=too-many-lines
 import time as _time
 import math as _math
+import re as _re
 from micropython import const
 
 __version__ = "0.0.0-auto.0"
@@ -62,6 +63,8 @@
 )
 _DAYNAMES = (None, "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun")
 
+_INVALID_ISO_ERROR = "Invalid isoformat string: '{}'"
+
 # Utility functions - universal
 def _cmp(obj_x, obj_y):
     return 0 if obj_x == obj_y else 1 if obj_x > obj_y else -1
@@ -657,6 +660,20 @@ def fromordinal(cls, ordinal):
         y, m, d = _ord2ymd(ordinal)
         return cls(y, m, d)
 
+    @classmethod
+    def fromisoformat(cls, date_string):
+        """Return a date object constructed from an ISO date format.
+        Valid format is ``YYYY-MM-DD``
+
+        """
+        match = _re.match(
+            r"([0-9][0-9][0-9][0-9])-([0-9][0-9])-([0-9][0-9])$", date_string
+        )
+        if match:
+            y, m, d = int(match.group(1)), int(match.group(2)), int(match.group(3))
+            return cls(y, m, d)
+        raise ValueError(_INVALID_ISO_ERROR.format(date_string))
+
     @classmethod
     def today(cls):
         """Return the current local date."""
@@ -907,6 +924,96 @@ def tzinfo(self):
         """
         return self._tzinfo
 
+    @staticmethod
+    def _parse_iso_string(string_to_parse, segments):
+        results = []
+
+        remaining_string = string_to_parse
+        for regex in segments:
+            match = _re.match(regex, remaining_string)
+            if match:
+                for grp in range(regex.count("(")):
+                    results.append(int(match.group(grp + 1)))
+                remaining_string = remaining_string[len(match.group(0)) :]
+            elif remaining_string:  # Only raise an error if we're not done yet
+                raise ValueError()
+        if remaining_string:
+            raise ValueError()
+        return results
+
+    # pylint: disable=too-many-locals
+    @classmethod
+    def fromisoformat(cls, time_string):
+        """Return a time object constructed from an ISO date format.
+        Valid format is ``HH[:MM[:SS[.fff[fff]]]][+HH:MM[:SS[.ffffff]]]``
+
+        """
+        # Store the original string in an error message
+        original_string = time_string
+        match = _re.match(r"(.*)[\-\+]", time_string)
+        offset_string = None
+        if match:
+            offset_string = time_string[len(match.group(1)) :]
+            time_string = match.group(1)
+
+        time_segments = (
+            r"([0-9][0-9])",
+            r":([0-9][0-9])",
+            r":([0-9][0-9])",
+            r"\.([0-9][0-9][0-9])",
+            r"([0-9][0-9][0-9])",
+        )
+        offset_segments = (
+            r"([\-\+][0-9][0-9]):([0-9][0-9])",
+            r":([0-9][0-9])",
+            r"\.([0-9][0-9][0-9][0-9][0-9][0-9])",
+        )
+
+        try:
+            results = cls._parse_iso_string(time_string, time_segments)
+            if len(results) < 1:
+                raise ValueError(_INVALID_ISO_ERROR.format(original_string))
+            if len(results) < len(time_segments):
+                results += [None] * (len(time_segments) - len(results))
+            if offset_string:
+                results += cls._parse_iso_string(offset_string, offset_segments)
+        except ValueError as error:
+            raise ValueError(_INVALID_ISO_ERROR.format(original_string)) from error
+
+        hh = results[0]
+        mm = results[1] if len(results) >= 2 and results[1] is not None else 0
+        ss = results[2] if len(results) >= 3 and results[2] is not None else 0
+        us = 0
+        if len(results) >= 4 and results[3] is not None:
+            us += results[3] * 1000
+        if len(results) >= 5 and results[4] is not None:
+            us += results[4]
+        tz = None
+        if len(results) >= 7:
+            offset_hh = results[5]
+            multiplier = -1 if offset_hh < 0 else 1
+            offset_mm = results[6] * multiplier
+            offset_ss = (results[7] if len(results) >= 8 else 0) * multiplier
+            offset_us = (results[8] if len(results) >= 9 else 0) * multiplier
+            offset = timedelta(
+                hours=offset_hh,
+                minutes=offset_mm,
+                seconds=offset_ss,
+                microseconds=offset_us,
+            )
+            tz = timezone(offset, name="utcoffset")
+
+        result = cls(
+            hh,
+            mm,
+            ss,
+            us,
+            tz,
+        )
+        return result
+
+    # pylint: enable=too-many-locals
+
     # Instance methods
     def isoformat(self, timespec="auto"):
         """Return a string representing the time in ISO 8601 format, one of:
@@ -1163,6 +1270,11 @@ def tzinfo(self):
         """
         return self._tzinfo
 
+    @property
+    def fold(self):
+        """Fold."""
+        return self._fold
+
     # Class methods
 
     # pylint: disable=protected-access
@@ -1206,6 +1318,29 @@ def _fromtimestamp(cls, t, utc, tz):
     def fromtimestamp(cls, timestamp, tz=None):
         return cls._fromtimestamp(timestamp, tz is not None, tz)
 
+    @classmethod
+    def fromisoformat(cls, date_string):
+        """Return a datetime object constructed from an ISO date format.
+        Valid format is ``YYYY-MM-DD[*HH[:MM[:SS[.fff[fff]]]][+HH:MM[:SS[.ffffff]]]]``
+
+        """
+        original_string = date_string
+
+        time_string = None
+        try:
+            if len(date_string) > 10:
+                time_string = date_string[11:]
+                date_string = date_string[:10]
+                dateval = date.fromisoformat(date_string)
+                timeval = time.fromisoformat(time_string)
+            else:
+                dateval = date.fromisoformat(date_string)
+                timeval = time()
+        except ValueError as error:
+            raise ValueError(_INVALID_ISO_ERROR.format(original_string)) from error
+
+        return cls.combine(dateval, timeval)
+
     @classmethod
     def now(cls, timezone=None):
         """Return the current local date and time."""

examples/datetime_simpletest.py

@@ -6,6 +6,7 @@
 #                         All rights reserved.
 # SPDX-FileCopyrightText: 1991-1995 Stichting Mathematisch Centrum. All rights reserved.
 # SPDX-FileCopyrightText: 2021 Brent Rubell for Adafruit Industries
+# SPDX-FileCopyrightText: 2021 Melissa LeBlanc-Williams for Adafruit Industries
 # SPDX-License-Identifier: Python-2.0
 
 # Example of working with a `datetime` object
@@ -28,3 +29,8 @@
     print(it)
 
 print("Today is: ", dt.ctime())
+
+iso_date_string = "2020-04-05T05:04:45.752301"
+print("Creating new datetime from ISO Date:", iso_date_string)
+isodate = datetime.fromisoformat(iso_date_string)
+print("Formatted back out as ISO Date: ", isodate.isoformat())

tests/test_date.py

@@ -88,6 +88,19 @@ def test_fromtimestamp(self):
         self.assertEqual(d.month, month)
         self.assertEqual(d.day, day)
 
+    def test_fromisoformat(self):
+        # Try an arbitrary fixed value.
+        iso_date_string = "1999-09-19"
+        d = cpy_date.fromisoformat(iso_date_string)
+        self.assertEqual(d.year, 1999)
+        self.assertEqual(d.month, 9)
+        self.assertEqual(d.day, 19)
+
+    def test_fromisoformat_bad_formats(self):
+        # Try an arbitrary fixed value.
+        self.assertRaises(ValueError, cpy_date.fromisoformat, "99-09-19")
+        self.assertRaises(ValueError, cpy_date.fromisoformat, "1999-13-19")
+
     # TODO: Test this when timedelta is added in
     @unittest.skip("Skip for CircuitPython - timedelta() not yet implemented.")
     def test_today(self):

tests/test_datetime.py

@@ -1033,8 +1033,6 @@ def __new__(cls, *args, **kwargs):
                 self.assertIsInstance(dt, DateTimeSubclass)
                 self.assertEqual(dt.extra, 7)
 
-    # TODO
-    @unittest.skip("timezone not implemented")
     def test_fromisoformat_datetime(self):
         # Test that isoformat() is reversible
         base_dates = [(1, 1, 1), (1900, 1, 1), (2004, 11, 12), (2017, 5, 30)]
@@ -1097,8 +1095,6 @@ def test_fromisoformat_timezone(self):
                 dt_rt = self.theclass.fromisoformat(dtstr)
                 assert dt == dt_rt, dt_rt
 
-    # TODO
-    @unittest.skip("fromisoformat not implemented")
     def test_fromisoformat_separators(self):
         separators = [
             " ",
@@ -1120,8 +1116,6 @@ def test_fromisoformat_separators(self):
                 dt_rt = self.theclass.fromisoformat(dtstr)
                 self.assertEqual(dt, dt_rt)
 
-    # TODO
-    @unittest.skip("fromisoformat not implemented")
     def test_fromisoformat_ambiguous(self):
         # Test strings like 2018-01-31+12:15 (where +12:15 is not a time zone)
         separators = ["+", "-"]
@@ -1134,7 +1128,7 @@ def test_fromisoformat_ambiguous(self):
                 self.assertEqual(dt, dt_rt)
 
     # TODO
-    @unittest.skip("fromisoformat not implemented")
+    @unittest.skip("_format_time not fully implemented")
     def test_fromisoformat_timespecs(self):
         datetime_bases = [(2009, 12, 4, 8, 17, 45, 123456), (2009, 12, 4, 8, 17, 45, 0)]
 
@@ -1161,8 +1155,6 @@ def test_fromisoformat_timespecs(self):
                         dt_rt = self.theclass.fromisoformat(dtstr)
                         self.assertEqual(dt, dt_rt)
 
-    # TODO
-    @unittest.skip("fromisoformat not implemented")
     def test_fromisoformat_fails_datetime(self):
         # Test that fromisoformat() fails on invalid values
         bad_strs = [
@@ -1201,14 +1193,12 @@ def test_fromisoformat_fails_datetime(self):
                 with self.assertRaises(ValueError):
                     self.theclass.fromisoformat(bad_str)
 
-    # TODO
-    @unittest.skip("fromisoformat not implemented")
     def test_fromisoformat_fails_surrogate(self):
         # Test that when fromisoformat() fails with a surrogate character as
         # the separator, the error message contains the original string
         dtstr = "2018-01-03\ud80001:0113"
 
-        with self.assertRaisesRegex(ValueError, re.escape(repr(dtstr))):
+        with self.assertRaisesRegex(ValueError, repr(dtstr)):
             self.theclass.fromisoformat(dtstr)
 
     # TODO
@@ -1219,8 +1209,6 @@ def test_fromisoformat_utc(self):
 
         self.assertIs(dt.tzinfo, timezone.utc)
 
-    # TODO
-    @unittest.skip("fromisoformat not implemented")
     def test_fromisoformat_subclass(self):
         class DateTimeSubclass(self.theclass):
             pass