Add template filter add_room_links

Add a filter which greps room patterns in a string and converts them to
a link to our twiki room map.

mpicms/base/templatetags/base_tags.py

@@ -1,4 +1,9 @@
+import re
+
 from django import template
+from django.template.defaultfilters import stringfilter
+from django.utils.html import conditional_escape
+from django.utils.safestring import mark_safe
 
 from mpicms.base.utils import get_room_link
 
@@ -26,3 +31,30 @@ def remove_i18n(url):
     if url.startswith('/en') or url.startswith('/de'):
         return url[3:] 
     return url
+
+
+# The ROOM_PATTERN should be in sync with the twiki plugin setting
+# in http://twiki.molgen.mpg.de/foswiki/System/RoomsPlugin
+
+ROOM_PATTERN = re.compile(
+        "("
+            r"R[0-4]\d\d[abc]?"
+            r"|[012]\.[012][012]\d\.?\d?[ab]?"
+            r"|B[01]\.[01][0-9]"
+            r"|KB\.0[01]|E[012]\da?"
+            r"|K4?\.[012][012]\d?(?:\.\d)?"
+            r"|K[B123]\.\d\d\d?[abc]?"
+            r"|W[012]\d[abc]?"
+            r"|K[TV]1?\.[012]\d[abcdefg]?"
+            r"|TH[0-5]\d[ab]?"
+            r"|HS\d\d"
+            r"|GH[01]\d"
+            r"|[K0123]\.[1234]\.F?\d\d"
+        ")" )
+
+@register.filter(needs_autoescape=True)
+@stringfilter
+def add_room_links(rooms, autoescape=True):
+        if autoescape:
+            rooms = conditional_escape(rooms)
+        return mark_safe(ROOM_PATTERN.sub(r'<a href="http://twiki.molgen.mpg.de/foswiki/bin/room/\1">\1</a>', rooms))