text: """ ``router`` module.
  """
  
  from warnings import warn
  
  from wheezy.routing.builders import build_route
  from wheezy.routing.config import route_builders as default_route_builders
  from wheezy.routing.utils import route_name
  
  
  def url(pattern, handler, kwargs=None, name=None):
      """Converts parameters to tupple of length four.
      Used for convenience to name parameters and skip
      unused.
      """
      return pattern, handler, kwargs, name
  
  
  class PathRouter(object):
      """"""
  
      __slots__ = (
          "mapping",
          "match_map",
          "path_map",
          "inner_path_map",
          "route_builders",
      )
  
      def __init__(self, route_builders=None):
          """"""
          self.route_builders = route_builders or default_route_builders
          # match
          self.match_map = {}
          self.mapping = []
          # path
          self.path_map = {}
          self.inner_path_map = {}
  
      def add_route(self, pattern, handler, kwargs=None, name=None):
          """Adds a pattern to route table"""
          name = name or route_name(handler)
          if name in self.path_map:  # pragma: nocover
              warn("PathRouter: overriding route: %s." % name)
          # build finishing route
          route = build_route(pattern, True, kwargs, name, self.route_builders)
          self.path_map[name] = route.path
          if route.exact_matches:
              for pattern, kwargs in route.exact_matches:
                  if pattern in self.match_map:  # pragma: nocover
                      warn("PathRouter: overriding path: %s." % pattern)
                  self.match_map[pattern] = (handler, kwargs)
              route.exact_matches = None
          else:
              self.mapping.append((route.match, handler))
  
      def include(self, pattern, included, kwargs=None):
          """Includes nested routes below the current."""
          # try build intermediate route
          route = build_route(pattern, False, kwargs, None, self.route_builders)
          if not isinstance(included, PathRouter):
              router = PathRouter(self.route_builders)
              router.add_routes(included)
              included = router
          if route.exact_matches:
              for p, kwargs in route.exact_matches:
                  for k, v in included.match_map.items():
                      k = p + k
                      if k in self.match_map:  # pragma: nocover
                          warn("PathRouter: overriding path: %s." % k)
                      h, kw = v
                      self.match_map[k] = (h, dict(kwargs, **kw))
              route.exact_matches = None
              included.match_map = {}
              if included.mapping:
                  self.mapping.append((route.match, included))
          else:
              self.mapping.append((route.match, included))
          route_path = route.path
          for name, path in included.path_map.items():
              if name in self.inner_path_map:  # pragma: nocover
                  warn("PathRouter: overriding route: %s." % name)
              self.inner_path_map[name] = (route_path, path)
          included.path_map = None
          for name, paths in included.inner_path_map.items():
              if name in self.inner_path_map:  # pragma: nocover
                  warn("PathRouter: overriding route: %s." % name)
              self.inner_path_map[name] = tuple([route_path] + list(paths))
          included.inner_path_map = None
          # print('include %s => %s / %s' % (pattern, len(self.match_map),
          #                                 len(included.mapping)))
  
      def add_routes(self, mapping):
          """Adds routes represented as a list of tuple
          (pattern, handler, kwargs=None, name=None) to route table.
          """
          for m in mapping:
              length = len(m)
              kwargs, name = None, None
              if length == 2:
                  pattern, handler = m
              elif length == 3:
                  pattern, handler, kwargs = m
              else:
                  pattern, handler, kwargs, name = m
              if isinstance(handler, (tuple, list, PathRouter)):
                  self.include(pattern, handler, kwargs)
              else:
                  self.add_route(pattern, handler, kwargs, name)
          # print('add_routes => %s / %s' % (len(self.match_map),
          #                                 len(self.mapping)))
  
      def match(self, path):
          """Tries to find a match for the given path in route table.
          Returns a tupple of (handler, kwargs)
          """
          if path in self.match_map:
              return self.match_map[path]
          for match, handler in self.mapping:
              matched, kwargs = match(path)
              if matched >= 0:
                  # TODO: isinstance(handler, PathRouter)
                  match = getattr(handler, "match", None)
                  if not match:
                      return handler, kwargs
                  handler, kwargs_inner = match(path[matched:])
                  if handler:
                      if not kwargs:
                          return handler, kwargs_inner
                      if kwargs_inner:
                          kwargs = dict(kwargs, **kwargs_inner)
                      return handler, kwargs
          return None, {}
  
      def path_for(self, name, **kwargs):
          """Returns the url for the given route name."""
          if name in self.path_map:
              return self.path_map[name](kwargs)
          else:
              return "".join(
                  [path(kwargs) for path in self.inner_path_map[name]]
              )
  