honor indirect relationships when looking for related polls

wortschlucker/src/wortschlucker.py

@@ -96,6 +96,13 @@ class Poll(sqlobject.SQLObject):
     timestamp_creation = sqlobject.DateTimeCol()
 
     def get_related_polls(self):
+        """ get all directly and indirectly connected polls up to a certain
+        distance
+        """
+        return PollMesh(self).get_related_polls()
+
+    def get_related_polls_direct(self):
+        """ get all directly connected polls """
         related = []
         related.extend([poll.second for poll in PollRelation.selectBy(first=self.id)])
         related.extend([poll.first for poll in PollRelation.selectBy(second=self.id)])
@@ -162,6 +169,32 @@ class Poll(sqlobject.SQLObject):
         return str(self.timestamp_creation)
 
 
+class PollMesh:
+    """ generate a mesh of directly or indirectly related polls
+
+    Basically this is just a recursive search for unique related polls that are
+    connected to the base poll with less than (e.g.) five nodes in between.
+    """
+
+    def __init__(self, poll, depth=5):
+        self.related = []
+        # start to collect the related polls immediately
+        self.__collect_related_polls(poll, depth)
+
+    def __collect_related_polls(self, current_poll, current_depth):
+        """ recursive scanning for unique related polls up to a certain distance
+        """
+        related = current_poll.get_related_polls_direct()
+        new_queue = [poll for poll in related if not poll in self.related]
+        self.related.extend(new_queue)
+        if current_depth > 0:
+            for poll in new_queue:
+                self.__collect_related_polls(poll, current_depth - 1)
+        
+    def get_related_polls(self):
+        return self.related
+        
+
 def validate_poll_setting(key, value):
     if not key in POLL_SETTINGS.keys():
         return None