fix date and datetime intervals from string

intervals/interval.py

@@ -8,12 +8,45 @@
 
 # -*- coding: utf-8 -*-
 import operator
+import sys
 from datetime import date, datetime, timedelta
 from decimal import Decimal
 from math import ceil, floor
 
 from infinity import inf, is_infinite
 
+try:
+    import arrow
+
+    def date_from_iso(s):
+        return arrow.get(s).naive.date()
+
+    def datetime_from_iso(s):
+        return arrow.get(s).naive
+
+except ImportError:
+    if (
+        sys.version_info.major > 3 or
+        (sys.version_info.major == 3 and sys.version_info.minor >= 7)
+    ):
+        def date_from_iso(s):
+            return date.fromisoformat(s)
+
+        def datetime_from_iso(s):
+            return datetime.fromisoformat(s)
+    else:
+        def date_from_iso(s):
+            return datetime.strptime(s, '%Y-%m-%d').date()
+
+        def datetime_from_iso(s):
+            n = len(s)
+            if n == 10:
+                return datetime.strptime(s, '%Y-%m-%d')
+            elif n == 19:
+                return datetime.strptime(s, '%Y-%m-%d %H:%M:%S')
+            elif n > 19:
+                return datetime.strptime(s, '%Y-%m-%d %H:%M:%S.%f')
+
 from .exc import IllegalArgument, IntervalException, RangeBoundsException
 from .parser import IntervalParser, IntervalStringParser
 
@@ -725,10 +758,16 @@ class DateInterval(AbstractInterval):
     step = timedelta(days=1)
     type = date
 
+    def coerce_string(self, value):
+        return date_from_iso(value)
+
 
 class DateTimeInterval(AbstractInterval):
     type = datetime
 
+    def coerce_string(self, value):
+        return datetime_from_iso(value)
+
 
 class FloatInterval(NumberInterval):
     type = float

tests/interval/test_initialization.py

@@ -1,16 +1,19 @@
 from datetime import date
+from datetime import datetime
 from decimal import Decimal
 
 from infinity import inf
 from pytest import mark, raises
 
 from intervals import (
     CharacterInterval,
+    DateInterval,
+    DateTimeInterval,
     DecimalInterval,
     FloatInterval,
     IllegalArgument,
-    Interval,
     IntInterval,
+    Interval,
     RangeBoundsException
 )
 
@@ -186,6 +189,29 @@ def test_raises_exception_for_badly_constructed_range(
         with raises(RangeBoundsException):
             constructor(number_range)
 
+    def test_dateinterval_fromstring(self):
+        s = '[2020-01-02, 2020-03-04]'
+        interval = DateInterval.from_string(s)
+        assert interval.lower == date(2020, 1, 2)
+        assert interval.upper == date(2020, 3, 4)
+        assert interval.lower_inc
+        assert interval.upper_inc
+
+    def test_datetimeinterval_fromstring(self):
+        s = '[2020-01-02 03:04:05, 2020-06-07 08:09:10.000001]'
+        interval = DateTimeInterval.from_string(s)
+        assert interval.lower == datetime(2020, 1, 2, 3, 4, 5)
+        assert interval.upper == datetime(2020, 6, 7, 8, 9, 10, 1)
+        assert interval.lower_inc
+        assert interval.upper_inc
+        # without time part
+        s = '[2020-01-02, 2020-06-07]'
+        interval = DateTimeInterval.from_string(s)
+        assert interval.lower == datetime(2020, 1, 2, 0, 0, 0)
+        assert interval.upper == datetime(2020, 6, 7, 0, 0, 0)
+        assert interval.lower_inc
+        assert interval.upper_inc
+
 
 class TestTypeGuessing(object):
     @mark.parametrize(