provide access to the parsed Nokogiri document fragment when rendering marked up content.

lib/gollum/markup.rb

@@ -44,7 +44,12 @@ module Gollum
       end
       data = process_tags(data)
       data = process_code(data)
-      data = sanitize.clean!(data) if sanitize
+      if sanitize || block_given?
+        doc  = Nokogiri::HTML::DocumentFragment.parse(data)
+        doc  = sanitize.clean_node!(doc) if sanitize
+        yield doc if block_given?
+        data = doc_to_html(doc)
+      end
       data = process_tex(data)
       data.gsub!(/<p><\/p>/, '')
       data

lib/gollum/page.rb

@@ -132,8 +132,8 @@ module Gollum
     # Public: The formatted contents of the page.
     #
     # Returns the String data.
-    def formatted_data
-      @blob && @wiki.markup_class.new(self).render(historical?)
+    def formatted_data(&block)
+      @blob && @wiki.markup_class.new(self).render(historical?, &block)
     end
 
     # Public: The format of the page.