Add an update_current argument to get_next/get_prev/all_next/all_pr…

…ev (#84)

This fixes #83 .

CHANGELOG.rst

@@ -4,8 +4,7 @@ Changelog
 3.0.1 (unreleased)
 ------------------
 
-- Nothing changed yet.
-
+- Add an `update_current` argument to get_next/get_prev/all_next/all_prev to facilitate writing of some downstream code, see #83. [kiorky]
 
 3.0.0 (2024-07-23)
 ------------------

src/croniter/croniter.py

@@ -232,14 +232,13 @@ def _alphaconv(cls, index, key, expressions):
             raise CroniterNotAlphaError(
                 "[{0}] is not acceptable".format(" ".join(expressions)))
 
-    def get_next(self, ret_type=None, start_time=None):
+    def get_next(self, ret_type=None, start_time=None, update_current=True):
         if start_time and self._expand_from_start_time:
             raise ValueError("start_time is not supported when using expand_from_start_time = True.")
-        self.set_current(start_time, force=True)
-        return self._get_next(ret_type or self._ret_type, is_prev=False)
+        return self._get_next(ret_type or self._ret_type, is_prev=False, update_current=update_current)
 
-    def get_prev(self, ret_type=None):
-        return self._get_next(ret_type or self._ret_type, is_prev=True)
+    def get_prev(self, ret_type=None, start_time=None, update_current=True):
+        return self._get_next(ret_type or self._ret_type, is_prev=True, update_current=update_current)
 
     def get_current(self, ret_type=None):
         ret_type = ret_type or self._ret_type
@@ -285,7 +284,9 @@ def _timedelta_to_seconds(cls, td):
         """
         return timedelta_to_seconds(td)
 
-    def _get_next(self, ret_type=None, start_time=None, is_prev=None):
+    def _get_next(self, ret_type=None, start_time=None, is_prev=None, update_current=None):
+        if update_current is None:
+            update_current = True
         self.set_current(start_time, force=True)
         if is_prev is None:
             is_prev = self._is_prev
@@ -360,7 +361,8 @@ def _get_next(self, ret_type=None, start_time=None, is_prev=None):
                     dtresult = dtresult_adjusted
                     result = result_adjusted
                 self.dst_start_time = result
-        self.cur = result
+        if update_current:
+            self.cur = result
         if issubclass(ret_type, datetime.datetime):
             result = dtresult
         return result
@@ -369,7 +371,7 @@ def _get_next(self, ret_type=None, start_time=None, is_prev=None):
     # objects in a loop, like "for dt in croniter('5 0 * * *'): ..."
     # or for combining multiple croniters into single
     # dates feed using 'itertools' module
-    def all_next(self, ret_type=None):
+    def all_next(self, ret_type=None, start_time=None, update_current=None):
         '''Generator of all consecutive dates. Can be used instead of
         implicit call to __iter__, whenever non-default
         'ret_type' has to be specified.
@@ -378,19 +380,21 @@ def all_next(self, ret_type=None):
         try:
             while True:
                 self._is_prev = False
-                yield self._get_next(ret_type or self._ret_type)
+                yield self._get_next(ret_type or self._ret_type,
+                                     start_time=start_time, update_current=update_current)
         except CroniterBadDateError:
             if self._max_years_btw_matches_explicitly_set:
                 return
             else:
                 raise
 
-    def all_prev(self, ret_type=None):
+    def all_prev(self, ret_type=None, start_time=None, update_current=None):
         '''Generator of all previous dates.'''
         try:
             while True:
                 self._is_prev = True
-                yield self._get_next(ret_type or self._ret_type)
+                yield self._get_next(ret_type or self._ret_type,
+                                     start_time=start_time, update_current=update_current)
         except CroniterBadDateError:
             if self._max_years_btw_matches_explicitly_set:
                 return

src/croniter/tests/test_croniter.py

@@ -1883,5 +1883,71 @@ def test_get_next_fails_with_expand_from_start_time_true(self):
         self.assertRaises(ValueError, expanded_croniter.get_next, datetime, start_time=datetime(2024, 7, 12))
 
 
+    def test_get_next_update_current(self):
+        cron = croniter("* * * * * *")
+
+        cron.set_current(datetime(2024, 7, 12), force=True)
+        retn = [(cron.get_next(datetime), cron.get_current(datetime))
+                for a in range(3)]
+        self.assertEqual(
+            retn,
+            [(datetime(2024, 7, 12, 0, 0, 1), datetime(2024, 7, 12, 0, 0, 1)),
+             (datetime(2024, 7, 12, 0, 0, 2), datetime(2024, 7, 12, 0, 0, 2)),
+             (datetime(2024, 7, 12, 0, 0, 3), datetime(2024, 7, 12, 0, 0, 3))]
+        )
+
+        cron.set_current(datetime(2024, 7, 12), force=True)
+        retp = [(cron.get_prev(datetime), cron.get_current(datetime))
+                for a in range(3)]
+        self.assertEqual(
+            retp,
+            [(datetime(2024, 7, 11, 23, 59, 59), datetime(2024, 7, 11, 23, 59, 59)),
+             (datetime(2024, 7, 11, 23, 59, 58), datetime(2024, 7, 11, 23, 59, 58)),
+             (datetime(2024, 7, 11, 23, 59, 57), datetime(2024, 7, 11, 23, 59, 57))]
+        )
+
+        cron.set_current(datetime(2024, 7, 12), force=True)
+        r = cron.all_next(datetime)
+        retan = [(next(r), cron.get_current(datetime)) for a in range(3)]
+
+        cron.set_current(datetime(2024, 7, 12), force=True)
+        r = cron.all_prev(datetime)
+        retap = [(next(r), cron.get_current(datetime)) for a in range(3)]
+
+        self.assertEqual(retp, retap)
+        self.assertEqual(retn, retan)
+
+        cron.set_current(datetime(2024, 7, 12), force=True)
+        uretn = [(cron.get_next(datetime, update_current=False), cron.get_current(datetime))
+                 for a in range(3)]
+        self.assertEqual(
+            uretn,
+            [(datetime(2024, 7, 12, 0, 0, 1), datetime(2024, 7, 12, 0, 0)),
+             (datetime(2024, 7, 12, 0, 0, 1), datetime(2024, 7, 12, 0, 0)),
+             (datetime(2024, 7, 12, 0, 0, 1), datetime(2024, 7, 12, 0, 0))]
+        )
+
+        cron.set_current(datetime(2024, 7, 12), force=True)
+        uretp = [(cron.get_prev(datetime, update_current=False), cron.get_current(datetime))
+                 for a in range(3)]
+        self.assertEqual(
+            uretp,
+            [(datetime(2024, 7, 11, 23, 59, 59), datetime(2024, 7, 12, 0, 0)),
+             (datetime(2024, 7, 11, 23, 59, 59), datetime(2024, 7, 12, 0, 0)),
+             (datetime(2024, 7, 11, 23, 59, 59), datetime(2024, 7, 12, 0, 0))]
+        )
+
+        cron.set_current(datetime(2024, 7, 12), force=True)
+        r = cron.all_next(datetime, update_current=False)
+        uretan = [(next(r), cron.get_current(datetime)) for a in range(3)]
+
+        cron.set_current(datetime(2024, 7, 12), force=True)
+        r = cron.all_prev(datetime, update_current=False)
+        uretap = [(next(r), cron.get_current(datetime)) for a in range(3)]
+
+        self.assertEqual(uretp, uretap)
+        self.assertEqual(uretn, uretan)
+
+
 if __name__ == '__main__':
     unittest.main()