Added a registry for tree builders and made it possible to find a tree builder that has the features you want from the BeautifulSoup constructor.

1 files changed, 14 insertions, 1 deletions

diff --git a/beautifulsoup/builder/_lxml.py b/beautifulsoup/builder/_lxml.py
index c2f368c..4c7a826 100644
--- a/beautifulsoup/builder/_lxml.py
+++ b/beautifulsoup/builder/_lxml.py
@@ -5,13 +5,24 @@ __all__ = [
 
 from lxml import etree
 from beautifulsoup.element import Comment, Doctype
-from beautifulsoup.builder import TreeBuilder, HTMLTreeBuilder
+from beautifulsoup.builder import (
+    FAST,
+    HTML,
+    HTMLTreeBuilder,
+    PERMISSIVE,
+    TreeBuilder,
+    XML)
 from beautifulsoup.dammit import UnicodeDammit
 import types
 
+LXML = 'lxml'
+
 class LXMLTreeBuilderForXML(TreeBuilder):
     DEFAULT_PARSER_CLASS = etree.XMLParser
 
+    # Well, it's permissive by XML parser standards.
+    features = [LXML, XML, FAST, PERMISSIVE]
+
     @property
     def default_parser(self):
         # This can either return a parser object or a class, which
@@ -79,6 +90,8 @@ class LXMLTreeBuilderForXML(TreeBuilder):
 
 class LXMLTreeBuilder(HTMLTreeBuilder, LXMLTreeBuilderForXML):
 
+    features = [LXML, HTML, FAST]
+
     @property
     def default_parser(self):
         return etree.HTMLParser