Create usable links for seminar rooms

For "events", room specifications like "SR 1" are often used. However,
this is not a valid room numer as expected by the twiki map.

Translate "SR [1234]" to correct room numbers for the link target.

mpicms/base/templatetags/base_tags.py

@@ -29,7 +29,6 @@ def remove_i18n(url):
 # 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]"
@@ -42,11 +41,27 @@ def remove_i18n(url):
             r"|HS\d\d"
             r"|GH[01]\d"
             r"|[K0123]\.[1234]\.F?\d\d"
-        ")" )
+            r"|SR ?([1234])" )
+
+SR_MAP= {
+    "1": "0.3.73",
+    "2": "0.3.05",
+    "3": "0.3.06",
+    "4": "0.2.01",
+}
+
+def room_match_to_link(match):
+    room = match.group(0)
+    target_room = room
+    if room.startswith("SR"):
+        sr_number = match.group(1)
+        if sr_number in SR_MAP:
+            target_room = SR_MAP[sr_number]
+    return '<a href="http://twiki.molgen.mpg.de/foswiki/bin/room/' + target_room + '">' + room + '</a>'
 
 @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))
+        return mark_safe(ROOM_PATTERN.sub(room_match_to_link, rooms))