Simplified django.utils.dateformat methods.

This removes unnecessary format('O') call, remove unnecessary method
calls for simple cases in TimeFormat, and simplifies time zone handling
in TimeFormat.

django/utils/dateformat.py

@@ -59,6 +59,13 @@ class TimeFormat(Formatter):
             else:
                 self.timezone = obj.tzinfo
 
+    @property
+    def _no_timezone_or_datetime_is_ambiguous_or_imaginary(self):
+        return (
+            not self.timezone or
+            _datetime_ambiguous_or_imaginary(self.data, self.timezone)
+        )
+
     def a(self):
         "'a.m.' or 'p.m.'"
         if self.data.hour > 11:
@@ -94,9 +101,9 @@ class TimeFormat(Formatter):
         Examples: '1', '1:30', '2:05', '2'
         Proprietary extension.
         """
-        if self.data.minute == 0:
-            return self.g()
-        return '%s:%s' % (self.g(), self.i())
+        hour = self.data.hour % 12 or 12
+        minute = self.data.minute
+        return '%d:%02d' % (hour, minute) if minute else hour
 
     def g(self):
         "Hour, 12-hour format without leading zeros; i.e. '1' to '12'"
@@ -108,11 +115,11 @@ class TimeFormat(Formatter):
 
     def h(self):
         "Hour, 12-hour format; i.e. '01' to '12'"
-        return '%02d' % self.g()
+        return '%02d' % (self.data.hour % 12 or 12)
 
     def H(self):
         "Hour, 24-hour format; i.e. '00' to '23'"
-        return '%02d' % self.G()
+        return '%02d' % self.data.hour
 
     def i(self):
         "Minutes; i.e. '00' to '59'"
@@ -124,12 +131,10 @@ class TimeFormat(Formatter):
 
         If timezone information is not available, return an empty string.
         """
-        if not self.timezone:
+        if self._no_timezone_or_datetime_is_ambiguous_or_imaginary:
             return ""
 
         seconds = self.Z()
-        if seconds == "":
-            return ""
         sign = '-' if seconds < 0 else '+'
         seconds = abs(seconds)
         return "%s%02d%02d" % (sign, seconds // 3600, (seconds // 60) % 60)
@@ -157,14 +162,10 @@ class TimeFormat(Formatter):
 
         If timezone information is not available, return an empty string.
         """
-        if not self.timezone:
+        if self._no_timezone_or_datetime_is_ambiguous_or_imaginary:
             return ""
 
-        if not _datetime_ambiguous_or_imaginary(self.data, self.timezone):
-            name = self.timezone.tzname(self.data)
-        else:
-            name = self.format('O')
-        return str(name)
+        return str(self.timezone.tzname(self.data))
 
     def u(self):
         "Microseconds; i.e. '000000' to '999999'"
@@ -178,10 +179,7 @@ class TimeFormat(Formatter):
 
         If timezone information is not available, return an empty string.
         """
-        if (
-            not self.timezone or
-            _datetime_ambiguous_or_imaginary(self.data, self.timezone)
-        ):
+        if self._no_timezone_or_datetime_is_ambiguous_or_imaginary:
             return ""
 
         offset = self.timezone.utcoffset(self.data)
@@ -223,10 +221,7 @@ class DateFormat(TimeFormat):
 
     def I(self):  # NOQA: E743, E741
         "'1' if Daylight Savings Time, '0' otherwise."
-        if (
-            not self.timezone or
-            _datetime_ambiguous_or_imaginary(self.data, self.timezone)
-        ):
+        if self._no_timezone_or_datetime_is_ambiguous_or_imaginary:
             return ''
         return '1' if self.timezone.dst(self.data) else '0'