Improved performance of _replace_cdata_list_attribute_values, and greatly reduced the number of times it is called.

1 files changed, 10 insertions, 8 deletions

diff --git a/bs4/builder/__init__.py b/bs4/builder/__init__.py
index e59dae2..740f5f2 100644
--- a/bs4/builder/__init__.py
+++ b/bs4/builder/__init__.py
@@ -147,16 +147,18 @@ class TreeBuilder(object):
 
         Modifies its input in place.
         """
+        if not attrs:
+            return attrs
         if self.cdata_list_attributes:
             universal = self.cdata_list_attributes.get('*', [])
             tag_specific = self.cdata_list_attributes.get(
-                tag_name.lower(), [])
-            for cdata_list_attr in itertools.chain(universal, tag_specific):
-                if cdata_list_attr in attrs:
-                    # Basically, we have a "class" attribute whose
-                    # value is a whitespace-separated list of CSS
-                    # classes. Split it into a list.
-                    value = attrs[cdata_list_attr]
+                tag_name.lower(), None)
+            for attr in attrs.keys():
+                if attr in universal or (tag_specific and attr in tag_specific):
+                    # We have a "class"-type attribute whose string
+                    # value is a whitespace-separated list of
+                    # values. Split it into a list.
+                    value = attrs[attr]
                     if isinstance(value, basestring):
                         values = whitespace_re.split(value)
                     else:
@@ -167,7 +169,7 @@ class TreeBuilder(object):
                         # leave the value alone rather than trying to
                         # split it again.
                         values = value
-                    attrs[cdata_list_attr] = values
+                    attrs[attr] = values
         return attrs
 
 class SAXTreeBuilder(TreeBuilder):