convert DateRangeIndex/UUIDIndex uniqueValues methods into generators

src/Products/PluginIndexes/DateRangeIndex/DateRangeIndex.py

@@ -213,7 +213,7 @@ def uniqueValues(self, name=None, withLengths=0):
         the form '(value, length)'.
         """
         if not name in (self._since_field, self._until_field):
-            return []
+            raise StopIteration
 
         if name == self._since_field:
             t1 = self._since
@@ -222,26 +222,22 @@ def uniqueValues(self, name=None, withLengths=0):
             t1 = self._until
             t2 = self._until_only
 
-        result = []
         if not withLengths:
-            result.extend(t1.keys())
-            result.extend(t2.keys())
-        else:
             for key in t1.keys():
-                set = t1[key]
-                if isinstance(set, int):
-                    length = 1
-                else:
-                    length = len(set)
-                result.append((key, length))
+                yield key
             for key in t2.keys():
-                set = t2[key]
-                if isinstance(set, int):
-                    length = 1
+                yield key
+        else:
+            for key, value in t1.items():
+                if isinstance(value, int):
+                    yield (key, 1)
+                else:
+                    yield (key, len(value))
+            for key, value in t2.items():
+                if isinstance(value, int):
+                    yield (key, 1)
                 else:
-                    length = len(set)
-                result.append((key, length))
-        return tuple(result)
+                    yield (key, len(value))
 
     def _cache_key(self, catalog):
         cid = catalog.getId()

src/Products/PluginIndexes/DateRangeIndex/tests.py

@@ -84,8 +84,8 @@ def test_empty(self):
         self.assertTrue(empty.getEntryForObject(1234) is None)
         empty.unindex_object(1234) # shouldn't throw
 
-        self.assertFalse(empty.uniqueValues('foo'))
-        self.assertFalse(empty.uniqueValues('foo', 1))
+        self.assertFalse(list(empty.uniqueValues('foo')))
+        self.assertFalse(list(empty.uniqueValues('foo', withLengths=True)))
         self.assertTrue(empty._apply_index({'zed': 12345}) is None)
 
         result, used = empty._apply_index({'empty': 12345})

src/Products/PluginIndexes/UUIDIndex/UUIDIndex.py

@@ -69,12 +69,15 @@ def uniqueValues(self, name=None, withLengths=0):
         if name is None:
             name = self.id
         elif name != self.id:
-            return []
+            raise StopIteration
 
         if not withLengths:
-            return tuple(self._index.keys())
-        # We know the length for each value is one
-        return [(k, 1) for k in self._index.keys()]
+            for key in self._index.keys():
+                yield key
+        else:
+            # We know the length for each value is one
+            for key in self._index.keys():
+                yield (key, 1)
 
     def insertForwardIndexEntry(self, entry, documentId):
         """Take the entry provided and put it in the correct place