bugdown: Linkify using a Markdown extension

This prevents trying to linkify inside code blocks.

(imported from commit 97dd20ecee19f41650aa98e68aa8e9908ece5b33)

zephyr/lib/bugdown/__init__.py

@@ -12,6 +12,14 @@ class Gravatar(markdown.inlinepatterns.Pattern):
             % (gravatar_hash(match.group('email')),))
         return img
 
+class AutoLink(markdown.inlinepatterns.Pattern):
+    def handleMatch(self, match):
+        url = match.group('url')
+        a = markdown.util.etree.Element('a')
+        a.set('href', url)
+        a.text = url
+        return a
+
 class Bugdown(markdown.Extension):
     def extendMarkdown(self, md, md_globals):
         del md.inlinePatterns['image_link']
@@ -21,6 +29,10 @@ class Bugdown(markdown.Extension):
 
         md.inlinePatterns.add('gravatar', Gravatar(r'!gravatar\((?P<email>[^)]*)\)'), '_begin')
 
+        # A link starts after whitespace and continues to the next whitespace.
+        link_regex = r'(\s|\A)(?P<url>https?://[^\s]+)'
+        md.inlinePatterns.add('autolink', AutoLink(link_regex), '_begin')
+
 # We need to re-initialize the markdown engine every 30 messages
 # due to some sort of performance leak in the markdown library.
 MAX_MD_ENGINE_USES = 30
@@ -28,11 +40,6 @@ MAX_MD_ENGINE_USES = 30
 _md_engine = None
 _use_count = 0
 
-# A link starts after whitespace, and cannot contain spaces,
-# end parentheses, or end brackets (which would confuse Markdown).
-# FIXME: Use one of the actual linkification extensions.
-_link_regex = re.compile(r'(\s|\A)(?P<url>https?://[^\s\])]+)')
-
 def _linkify(match):
     url = match.group('url')
     return ' [%s](%s) ' % (url, url)
@@ -49,8 +56,6 @@ def convert(md):
                 codehilite.makeExtension(configs=[('force_linenos', False)]),
                 Bugdown()])
 
-    md = _link_regex.sub(_linkify, md)
-
     try:
         html = _md_engine.convert(md)
     except: