From 2a34fbe043d5c4ba789e866a912646aea1bb807c Mon Sep 17 00:00:00 2001
From: Malcolm Tredinnick <malcolm.tredinnick@gmail.com>
Date: Sun, 17 Jun 2007 07:33:18 +0000
Subject: [PATCH] Fixed #4506 -- Changed "regroup" template tag to use __eq__
 instead of repr() for grouping equality checking. Thanks, Brian Harring.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@5484 bcc190cf-cafb-0310-a4f2-bffc1f526a37
---
 django/template/defaulttags.py | 14 +++++---------
 django/utils/itercompat.py     | 24 +++++++++++++++++++++++-
 2 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/django/template/defaulttags.py b/django/template/defaulttags.py
index 45005fa9889..77fac6bec54 100644
--- a/django/template/defaulttags.py
+++ b/django/template/defaulttags.py
@@ -4,6 +4,7 @@ from django.template import Node, NodeList, Template, Context, resolve_variable
 from django.template import TemplateSyntaxError, VariableDoesNotExist, BLOCK_TAG_START, BLOCK_TAG_END, VARIABLE_TAG_START, VARIABLE_TAG_END, SINGLE_BRACE_START, SINGLE_BRACE_END, COMMENT_TAG_START, COMMENT_TAG_END
 from django.template import get_library, Library, InvalidTemplateLibrary
 from django.conf import settings
+from django.utils.itercompat import groupby
 import sys
 import re
 
@@ -258,15 +259,10 @@ class RegroupNode(Node):
         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):
diff --git a/django/utils/itercompat.py b/django/utils/itercompat.py
index 370988bedbf..48a2d99d3af 100644
--- a/django/utils/itercompat.py
+++ b/django/utils/itercompat.py
@@ -7,7 +7,8 @@ these implementations if necessary.
 import itertools
 
 def compat_tee(iterable):
-    """Return two independent iterators from a single iterable.
+    """
+    Return two independent iterators from a single iterable.
 
     Based on http://www.python.org/doc/2.3.5/lib/itertools-example.html
     """
@@ -25,7 +26,28 @@ def compat_tee(iterable):
     next = iter(iterable).next
     return gen(next), gen(next)
 
+def groupby(iterable, keyfunc=None):
+    """
+    Taken from http://docs.python.org/lib/itertools-functions.html
+    """
+    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 hasattr(itertools, 'tee'):
     tee = itertools.tee
 else:
     tee = compat_tee
+if hasattr(itertools, 'groupby'):
+    groupby = itertools.groupby