Ticket #4506: RegroupNode-groupby-v2.patch

django/template/defaulttags.py

@@ -7 +7 @@
 import sys
 import re
 
+try:
+    from itertools import groupby
+except ImportError:
+    # we fall back to a simplified version of groupby, mainly for speed reasons.
+    # for the 'official' version, pull it from
+    # http://docs.python.org/lib/itertools-functions.html
+
+    def groupby(iterable, keyfunc=None):
+        if keyfunc is None:
+            keyfunc = lambda x:x
+        iterable = iter(iterable)
+        l = [iterable.next()]
+        lastkey = keyfunc(l)
+        for item in iterable:
+            key = keyfunc(item)
+            if key != lastkey:
+                yield lastkey, l
+                lastkey = key
+                l = [item]
+            else:
+                l.append(item)
+        yield lastkey, l
+
 if not hasattr(__builtins__, 'reversed'):
     # For Python 2.3.
     # From http://www.python.org/doc/current/tut/node11.html
@@ -252 +275 @@
         if obj_list == None: # target_var wasn't found in context; fail silently
             context[self.var_name] = []
             return ''
-        output = [] # list of dictionaries in the format {'grouper': 'key', 'list': [list of contents]}
-        for obj in obj_list:
-            grouper = self.expression.resolve(obj, True)
-            # TODO: Is this a sensible way to determine equality?
-            if output and repr(output[-1]['grouper']) == repr(grouper):
-                output[-1]['list'].append(obj)
-            else:
-                output.append({'grouper': grouper, 'list': [obj]})
-        context[self.var_name] = output
+        # list of dictionaries in the format {'grouper': 'key', 'list': [list of contents]}
+        context[self.var_name] = [{'grouper':key, 'list':list(val)} for key, val in
+            groupby(obj_list, lambda v, f=self.expression.resolve: f(v, True))]
         return ''
 
 def include_is_allowed(filepath):