koperkapel/actors/navigator.py

   1 """ A navigable graph of actors. """
   2
   3
   4 class ActorNavigator:
   5     """ A navigable graph of actors. """
   6
   7     def __init__(self):
   8         self._actors = {}
   9         self._graph = {}
  10         self._current_id = None
  11
  12     @property
  13     def current(self):
  14         return self._actors.get(self._current_id)
  15
  16     def connect_pair(self, a1, a2, edge):
  17         self._actors[id(a1)] = a1
  18         self._actors[id(a2)] = a2
  19         if self._current_id is None:
  20             self._current_id = id(a1)
  21         a1edges = self._graph.setdefault(id(a1), {})
  22         a1edges[edge] = id(a2)
  23
  24     def connect(self, actors, edges, reverse=None, wrap=True):
  25         if not edges or not actors:
  26             return
  27         first, previous, current = None, None, None
  28         for actor in actors:
  29             previous, current = current, actor
  30             if previous is None:
  31                 first = current
  32                 continue
  33             for edge in edges:
  34                 self.connect_pair(previous, current, edge)
  35         if wrap and first is not current:
  36             for edge in edges:
  37                 self.connect_pair(current, first, edge)
  38         if reverse is not None:
  39             self.connect(list(reversed(actors)), reverse)
  40
  41     def follow(self, edge):
  42         future = self._graph.get(self._current_id, {}).get(edge)
  43         if future:
  44             old, self._current_id = self._current_id, future
  45             return self._actors[old], self._actors[future]
  46         return None, None