Use is_iterator function to determine if the response content is iterable, rather than just testing if it is a generator.

This is in preparation for a fix for #1288. Note - we could test against
collections.Iterator, but this seems like a cleaner way of doing it for now.

3 files changed, 17 insertions, 4 deletions

diff --git a/cherrypy/lib/__init__.py b/cherrypy/lib/__init__.py
index 554b3920..2c851ec4 100644
--- a/cherrypy/lib/__init__.py
+++ b/cherrypy/lib/__init__.py
@@ -3,6 +3,19 @@
 # Deprecated in CherryPy 3.2 -- remove in CherryPy 3.3
 from cherrypy.lib.reprconf import unrepr, modules, attributes
 
+def is_iterator(obj):
+    '''Returns a boolean indicating if the object provided implements
+     the iterator protocol (i.e. like a generator). This will return
+     false for objects which iterable, but not iterators themselves.'''
+    from types import GeneratorType
+    if isinstance(obj, GeneratorType):
+        return True
+    elif not hasattr(obj, '__iter__'):
+        return False
+    else:
+        # Types which implement the protocol must return themselves when
+        # invoking 'iter' upon them.
+        return iter(obj) is obj
 
 class file_generator(object):
 
diff --git a/cherrypy/lib/cptools.py b/cherrypy/lib/cptools.py
index 134c8e47..66c9c1b8 100644
--- a/cherrypy/lib/cptools.py
+++ b/cherrypy/lib/cptools.py
@@ -6,6 +6,7 @@ import re
 import cherrypy
 from cherrypy._cpcompat import basestring, md5, set, unicodestr
 from cherrypy.lib import httputil as _httputil
+from cherrypy.lib import is_iterator
 
 
 #                     Conditional HTTP request support                     #
@@ -493,12 +494,10 @@ def flatten(debug=False):
     This allows cherrypy.response.body to consist of 'nested generators';
     that is, a set of generators that yield generators.
     """
-    import types
-
     def flattener(input):
         numchunks = 0
         for x in input:
-            if not isinstance(x, types.GeneratorType):
+            if not is_iterator(x):
                 numchunks += 1
                 yield x
             else:
diff --git a/cherrypy/lib/sessions.py b/cherrypy/lib/sessions.py
index 23115c50..42c89d8c 100644
--- a/cherrypy/lib/sessions.py
+++ b/cherrypy/lib/sessions.py
@@ -101,6 +101,7 @@ from cherrypy._cpcompat import copyitems, pickle, random20, unicodestr
 from cherrypy.lib import httputil
 from cherrypy.lib import lockfile
 from cherrypy.lib import locking
+from cherrypy.lib import is_iterator
 
 missing = object()
 
@@ -778,7 +779,7 @@ def save():
     else:
         # If the body is not being streamed, we save the data now
         # (so we can release the lock).
-        if isinstance(response.body, types.GeneratorType):
+        if is_iterator(response.body):
             response.collapse_body()
         cherrypy.session.save()
 save.failsafe = True