Update calendar.py from CPython 3.11

Author: carlosmiei

Lib/calendar.py

@@ -15,7 +15,9 @@
            "monthcalendar", "prmonth", "month", "prcal", "calendar",
            "timegm", "month_name", "month_abbr", "day_name", "day_abbr",
            "Calendar", "TextCalendar", "HTMLCalendar", "LocaleTextCalendar",
-           "LocaleHTMLCalendar", "weekheader"]
+           "LocaleHTMLCalendar", "weekheader",
+           "MONDAY", "TUESDAY", "WEDNESDAY", "THURSDAY", "FRIDAY",
+           "SATURDAY", "SUNDAY"]
 
 # Exception raised for bad input (with string parameter for details)
 error = ValueError
@@ -546,71 +548,67 @@ def formatyearpage(self, theyear, width=3, css='calendar.css', encoding=None):
 class different_locale:
     def __init__(self, locale):
         self.locale = locale
+        self.oldlocale = None
 
     def __enter__(self):
-        self.oldlocale = _locale.getlocale(_locale.LC_TIME)
+        self.oldlocale = _locale.setlocale(_locale.LC_TIME, None)
         _locale.setlocale(_locale.LC_TIME, self.locale)
 
     def __exit__(self, *args):
+        if self.oldlocale is None:
+            return
         _locale.setlocale(_locale.LC_TIME, self.oldlocale)
 
 
+def _get_default_locale():
+    locale = _locale.setlocale(_locale.LC_TIME, None)
+    if locale == "C":
+        with different_locale(""):
+            # The LC_TIME locale does not seem to be configured:
+            # get the user preferred locale.
+            locale = _locale.setlocale(_locale.LC_TIME, None)
+    return locale
+
+
 class LocaleTextCalendar(TextCalendar):
     """
     This class can be passed a locale name in the constructor and will return
-    month and weekday names in the specified locale. If this locale includes
-    an encoding all strings containing month and weekday names will be returned
-    as unicode.
+    month and weekday names in the specified locale.
     """
 
     def __init__(self, firstweekday=0, locale=None):
         TextCalendar.__init__(self, firstweekday)
         if locale is None:
-            locale = _locale.getdefaultlocale()
+            locale = _get_default_locale()
         self.locale = locale
 
     def formatweekday(self, day, width):
         with different_locale(self.locale):
-            if width >= 9:
-                names = day_name
-            else:
-                names = day_abbr
-            name = names[day]
-            return name[:width].center(width)
+            return super().formatweekday(day, width)
 
     def formatmonthname(self, theyear, themonth, width, withyear=True):
         with different_locale(self.locale):
-            s = month_name[themonth]
-            if withyear:
-                s = "%s %r" % (s, theyear)
-            return s.center(width)
+            return super().formatmonthname(theyear, themonth, width, withyear)
 
 
 class LocaleHTMLCalendar(HTMLCalendar):
     """
     This class can be passed a locale name in the constructor and will return
-    month and weekday names in the specified locale. If this locale includes
-    an encoding all strings containing month and weekday names will be returned
-    as unicode.
+    month and weekday names in the specified locale.
     """
     def __init__(self, firstweekday=0, locale=None):
         HTMLCalendar.__init__(self, firstweekday)
         if locale is None:
-            locale = _locale.getdefaultlocale()
+            locale = _get_default_locale()
         self.locale = locale
 
     def formatweekday(self, day):
         with different_locale(self.locale):
-            s = day_abbr[day]
-            return '<th class="%s">%s</th>' % (self.cssclasses[day], s)
+            return super().formatweekday(day)
 
     def formatmonthname(self, theyear, themonth, withyear=True):
         with different_locale(self.locale):
-            s = month_name[themonth]
-            if withyear:
-                s = '%s %s' % (s, theyear)
-            return '<tr><th colspan="7" class="month">%s</th></tr>' % s
-
+            return super().formatmonthname(theyear, themonth, withyear)
 
 # Support for old module level interface
 c = TextCalendar()