+
+ def proxy(self):
+ return WorldDictProxy(self._state)
+
+ def apply_event(self, action, *args, **kw):
+ handler = getattr(self, "_apply_%s" % (action,))
+ return handler(action, *args, **kw)
+
+
+def _maybe_subproxy(proxy, name, value):
+ """ Return a sub world proxy if appropriate. """
+ if isinstance(value, dict):
+ prefix = "%s%s." % (proxy._prefix, name)
+ return WorldDictProxy(value, _prefix=prefix, _top=proxy._top)
+ elif isinstance(value, list):
+ prefix = "%s%s." % (proxy._prefix, name)
+ return WorldListProxy(value, _prefix=prefix, _top=proxy._top)
+ return value
+
+
+class WorldBaseProxy:
+ """ Base for world proxies. """
+
+ def __init__(self, state, _prefix='', _top=None):
+ if _top is None:
+ _top = self
+ _events = []
+ else:
+ _events = None
+ self.__dict__.update({
+ "_state": state,
+ "_prefix": _prefix,
+ "_top": _top,
+ "_events": _events,
+ })
+
+ def _record_change(self, fullname, value, action="set"):
+ self._events.append(WorldEvent(action, {
+ fullname: value
+ }))
+
+ def pop_events(self):
+ events, self._events = self._events, []
+ return events
+
+
+class WorldDictProxy(WorldBaseProxy):
+ """ World dictionary proxy that records changes and produces events. """
+
+ def __setattr__(self, name, value):
+ self._top._record_change("%s%s" % (self._prefix, name), value)
+
+ def __getattr__(self, name):
+ # return None for attributes that don't exist
+ value = self._state.get(name)
+ return _maybe_subproxy(self, name, value)
+
+ def __setitem__(self, name, value):
+ return self.__setattr__(name, value)
+
+ def __getitem__(self, name):
+ return self.__getattr__(name)
+
+ def items(self):
+ return (
+ (k, _maybe_subproxy(self, k, v)) for k, v in self._state.items())
+
+
+class WorldListProxy(WorldBaseProxy):
+ """ World list proxy that records changes and produces events. """
+
+ def __setitem__(self, index, value):
+ self._top._record_change("%s%s" % (self._prefix, index), value)
+
+ def __getitem__(self, index):
+ return _maybe_subproxy(self, index, self._state[index])
+
+ def __len__(self):
+ return len(self._state)
+
+ def __bool__(self):
+ return bool(self._state)
+
+ def append(self, value):
+ self._top._record_change(self._prefix, value, action="append")
+
+ def pop(self, pos=0):
+ self._top._record_change(self._prefix, pos, action="pop")