accept_language parse; fix priority order; preserve insertion order

There are conditions under which the order is not correctly returned.

Use hashq.hashpop in a loop to get items out of hash (list) in proper
priority order. Make 3 element tuples in hashq include insertion
order. This makes tuples inserted later lower in priority when
priority q values are the same. Makes:

  "zn;q=1.0;q= 1.0,pt-br,en-US; q=0.5"

return ['zn', 'pt_br', 'en_US'] (pt_br is default prio of 1 like
zn). Otherwise we get ['pt_br', 'zn', 'en_US'] since 'p' > 'z'.

Author: rouilj

roundup/cgi/accept_language.py

@@ -64,15 +64,18 @@ def parse(language_header):
     # use a heap queue to sort by quality values.
     # the value of each item is 1.0 complement.
     pq = []
+    order=0
     for l in qls:
+        order +=1
         if l[0] != '':
-            heapq.heappush(pq, (0.0, l[0]))
+            heapq.heappush(pq, (0.0, order, l[0]))
         else:
-            heapq.heappush(pq, (1.0-float(l[2]), l[1]))
+            heapq.heappush(pq, (1.0-float(l[2]), order, l[1]))
 
     # get the languages ordered by quality
     # and replace - by _
-    return [x[1].replace('-', '_') for x in pq]
+    return [ heapq.heappop(pq)[2].replace('-','_') 
+             for x in range(len(pq)) ]
 
 if __name__ == "__main__":
     import doctest

test/test_misc.py

@@ -8,8 +8,18 @@ class AcceptLanguageTest(unittest.TestCase):
     def testParse(self):
         self.assertEqual(parse("da, en-gb;q=0.8, en;q=0.7"),
                          ['da', 'en_gb', 'en'])
+        self.assertEqual(parse("da, en-gb;q=0.7, en;q=0.8"),
+                         ['da', 'en', 'en_gb'])
         self.assertEqual(parse("en;q=0.2, fr;q=1"), ['fr', 'en'])
         self.assertEqual(parse("zn; q = 0.2 ,pt-br;q =1"), ['pt_br', 'zn'])
+        self.assertEqual(parse("pt-br;q =1, zn; q = 0.2"), ['pt_br', 'zn'])
+        self.assertEqual(parse("pt-br,zn;q= 0.1, en-US;q=0.5"),
+                         ['pt_br', 'en_US', 'zn'])
+        # verify that items with q=1.0 are in same output order as input
+        self.assertEqual(parse("pt-br,en-US; q=0.5, zn;q= 1.0" ),
+                         ['pt_br', 'zn', 'en_US'])
+        self.assertEqual(parse("zn;q=1.0;q= 1.0,pt-br,en-US; q=0.5" ),
+                         ['zn', 'pt_br', 'en_US'])
         self.assertEqual(parse("es-AR"), ['es_AR'])
         self.assertEqual(parse("es-es-cat"), ['es_es_cat'])
         self.assertEqual(parse(""), [])