json_clean: Some performance improvements

Author: martinRenou

ipykernel/jsonutil.py

@@ -43,6 +43,7 @@
 # front of PDF base64-encoded
 PDF64 = b'JVBER'
 
+
 def encode_images(format_dict):
     """b64-encodes images in a displaypub format dict
 
@@ -91,15 +92,15 @@ def json_clean(obj):
 
     """
     # types that are 'atomic' and ok in json as-is.
-    atomic_ok = (str, type(None))
+    atomic_ok = (bool, str, type(None))
 
     # containers that we need to convert into lists
-    container_to_list = (tuple, set, types.GeneratorType)
+    container_to_list = (list, tuple, set, types.GeneratorType)
 
     # Since bools are a subtype of Integrals, which are a subtype of Reals,
     # we have to check them in that order.
 
-    if isinstance(obj, bool):
+    if isinstance(obj, atomic_ok):
         return obj
 
     if isinstance(obj, numbers.Integral):
@@ -111,20 +112,14 @@ def json_clean(obj):
         if math.isnan(obj) or math.isinf(obj):
             return repr(obj)
         return float(obj)
-    
-    if isinstance(obj, atomic_ok):
-        return obj
-    
+
     if isinstance(obj, bytes):
         # unanmbiguous binary data is base64-encoded
         # (this probably should have happened upstream)
         return b2a_base64(obj).decode('ascii')
 
     if isinstance(obj, container_to_list) or (
         hasattr(obj, '__iter__') and hasattr(obj, next_attr_name)):
-        obj = list(obj)
-
-    if isinstance(obj, list):
         return [json_clean(x) for x in obj]
 
     if isinstance(obj, dict):
@@ -138,11 +133,12 @@ def json_clean(obj):
                              'key collision would lead to dropped values')
         # If all OK, proceed by making the new dict that will be json-safe
         out = {}
-        for k,v in obj.items():
+        for k, v in obj.items():
             out[str(k)] = json_clean(v)
         return out
+
     if isinstance(obj, datetime):
         return obj.strftime(ISO8601)
-    
+
     # we don't understand it, it's probably an unserializable object
     raise ValueError("Can't clean for JSON: %r" % obj)