Class _ApplicationRouter

python/python3/tornado/web.py:1922–1958

Routing implementation used internally by `Application`. Provides a binding between `Application` and `RequestHandler`. This implementation extends `~.routing.ReversibleRuleRouter` in a couple of ways: * it allows to use `RequestHandler` subclasses as `~.routing.Rule` target and

class _ApplicationRouter(ReversibleRuleRouter):
    """Routing implementation used internally by `Application`.

    Provides a binding between `Application` and `RequestHandler`.
    This implementation extends `~.routing.ReversibleRuleRouter` in a couple of ways:
        * it allows to use `RequestHandler` subclasses as `~.routing.Rule` target and
        * it allows to use a list/tuple of rules as `~.routing.Rule` target.
        ``process_rule`` implementation will substitute this list with an appropriate
        `_ApplicationRouter` instance.
    """

    def __init__(
        self, application: "Application", rules: Optional[_RuleList] = None
    ) -> None:
        assert isinstance(application, Application)
        self.application = application
        super().__init__(rules)

    def process_rule(self, rule: Rule) -> Rule:
        rule = super().process_rule(rule)

        if isinstance(rule.target, (list, tuple)):
            rule.target = _ApplicationRouter(
                self.application, rule.target  # type: ignore
            )

        return rule

    def get_target_delegate(
        self, target: Any, request: httputil.HTTPServerRequest, **target_params: Any
    ) -> Optional[httputil.HTTPMessageDelegate]:
        if isclass(target) and issubclass(target, RequestHandler):
            return self.application.get_handler_delegate(
                request, target, **target_params
            )

        return super().get_target_delegate(target, request, **target_params)


class Application(ReversibleRouter):