text: from __future__ import annotations
  
  import asyncio
  
  from inspect import isawaitable
  from typing import Any, Dict, List, Optional, Tuple, Union
  
  from sanic_routing import BaseRouter, Route, RouteGroup  # type: ignore
  from sanic_routing.exceptions import NotFound  # type: ignore
  from sanic_routing.utils import path_to_parts  # type: ignore
  
  from sanic.exceptions import InvalidSignal
  from sanic.log import error_logger, logger
  from sanic.models.handler_types import SignalHandler
  
  
  RESERVED_NAMESPACES = {
      "server": (
          # "server.main.start",
          # "server.main.stop",
          "server.init.before",
          "server.init.after",
          "server.shutdown.before",
          "server.shutdown.after",
      ),
      "http": (
          "http.lifecycle.begin",
          "http.lifecycle.complete",
          "http.lifecycle.exception",
          "http.lifecycle.handle",
          "http.lifecycle.read_body",
          "http.lifecycle.read_head",
          "http.lifecycle.request",
          "http.lifecycle.response",
          "http.routing.after",
          "http.routing.before",
          "http.lifecycle.send",
          "http.middleware.after",
          "http.middleware.before",
      ),
  }
  
  
  def _blank():
      ...
  
  
  class Signal(Route):
      ...
  
  
  class SignalGroup(RouteGroup):
      ...
  
  
  class SignalRouter(BaseRouter):
      def __init__(self) -> None:
          super().__init__(
              delimiter=".",
              route_class=Signal,
              group_class=SignalGroup,
              stacking=True,
          )
          self.ctx.loop = None
  
      def get(  # type: ignore
          self,
          event: str,
          condition: Optional[Dict[str, str]] = None,
      ):
          extra = condition or {}
          try:
              group, param_basket = self.find_route(
                  f".{event}",
                  self.DEFAULT_METHOD,
                  self,
                  {"__params__": {}, "__matches__": {}},
                  extra=extra,
              )
          except NotFound:
              message = "Could not find signal %s"
              terms: List[Union[str, Optional[Dict[str, str]]]] = [event]
              if extra:
                  message += " with %s"
                  terms.append(extra)
              raise NotFound(message % tuple(terms))
  
          # Regex routes evaluate and can extract params directly. They are set
          # on param_basket["__params__"]
          params = param_basket["__params__"]
          if not params:
              # If param_basket["__params__"] does not exist, we might have
              # param_basket["__matches__"], which are indexed based matches
              # on path segments. They should already be cast types.
              params = {
                  param.name: param_basket["__matches__"][idx]
                  for idx, param in group.params.items()
              }
  
          return group, [route.handler for route in group], params
  
      async def _dispatch(
          self,
          event: str,
          context: Optional[Dict[str, Any]] = None,
          condition: Optional[Dict[str, str]] = None,
          fail_not_found: bool = True,
          reverse: bool = False,
      ) -> Any:
          try:
              group, handlers, params = self.get(event, condition=condition)
          except NotFound as e:
              if fail_not_found:
                  raise e
              else:
                  if self.ctx.app.debug:
                      error_logger.warning(str(e))
                  return None
  
          events = [signal.ctx.event for signal in group]
          for signal_event in events:
              signal_event.set()
          if context:
              params.update(context)
  
          if not reverse:
              handlers = handlers[::-1]
          try:
              for handler in handlers:
                  if condition is None or condition == handler.__requirements__:
                      maybe_coroutine = handler(**params)
                      if isawaitable(maybe_coroutine):
                          retval = await maybe_coroutine
                          if retval:
                              return retval
                      elif maybe_coroutine:
                          return maybe_coroutine
              return None
          finally:
              for signal_event in events:
                  signal_event.clear()
  
      async def dispatch(
          self,
          event: str,
          *,
          context: Optional[Dict[str, Any]] = None,
          condition: Optional[Dict[str, str]] = None,
          fail_not_found: bool = True,
          inline: bool = False,
          reverse: bool = False,
      ) -> Union[asyncio.Task, Any]:
          dispatch = self._dispatch(
              event,
              context=context,
              condition=condition,
              fail_not_found=fail_not_found and inline,
              reverse=reverse,
          )
          logger.debug(f"Dispatching signal: {event}")
  
          if inline:
              return await dispatch
  
          task = asyncio.get_running_loop().create_task(dispatch)
          await asyncio.sleep(0)
          return task
  
      def add(  # type: ignore
          self,
          handler: SignalHandler,
          event: str,
          condition: Optional[Dict[str, Any]] = None,
      ) -> Signal:
          parts = self._build_event_parts(event)
          if parts[2].startswith("<"):
              name = ".".join([*parts[:-1], "*"])
          else:
              name = event
  
          handler.__requirements__ = condition  # type: ignore
  
          return super().add(
              event,
              handler,
              requirements=condition,
              name=name,
              append=True,
          )  # type: ignore
  
      def finalize(self, do_compile: bool = True, do_optimize: bool = False):
          self.add(_blank, "sanic.__signal__.__init__")
  
          try:
              self.ctx.loop = asyncio.get_running_loop()
          except RuntimeError:
              raise RuntimeError("Cannot finalize signals outside of event loop")
  
          for signal in self.routes:
              signal.ctx.event = asyncio.Event()
  
          return super().finalize(do_compile=do_compile, do_optimize=do_optimize)
  
      def _build_event_parts(self, event: str) -> Tuple[str, str, str]:
          parts = path_to_parts(event, self.delimiter)
          if (
              len(parts) != 3
              or parts[0].startswith("<")
              or parts[1].startswith("<")
          ):
              raise InvalidSignal("Invalid signal event: %s" % event)
  
          if (
              parts[0] in RESERVED_NAMESPACES
              and event not in RESERVED_NAMESPACES[parts[0]]
              and not (parts[2].startswith("<") and parts[2].endswith(">"))
          ):
              raise InvalidSignal(
                  "Cannot declare reserved signal event: %s" % event
              )
          return parts
  