642 lines
22 KiB
Python
642 lines
22 KiB
Python
# Copyright 2015 The Tornado Authors
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""Flexible routing implementation.
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Tornado routes HTTP requests to appropriate handlers using `Router`
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class implementations. The `tornado.web.Application` class is a
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`Router` implementation and may be used directly, or the classes in
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this module may be used for additional flexibility. The `RuleRouter`
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class can match on more criteria than `.Application`, or the `Router`
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interface can be subclassed for maximum customization.
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`Router` interface extends `~.httputil.HTTPServerConnectionDelegate`
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to provide additional routing capabilities. This also means that any
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`Router` implementation can be used directly as a ``request_callback``
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for `~.httpserver.HTTPServer` constructor.
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`Router` subclass must implement a ``find_handler`` method to provide
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a suitable `~.httputil.HTTPMessageDelegate` instance to handle the
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request:
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.. code-block:: python
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class CustomRouter(Router):
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def find_handler(self, request, **kwargs):
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# some routing logic providing a suitable HTTPMessageDelegate instance
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return MessageDelegate(request.connection)
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class MessageDelegate(HTTPMessageDelegate):
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def __init__(self, connection):
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self.connection = connection
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def finish(self):
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self.connection.write_headers(
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ResponseStartLine("HTTP/1.1", 200, "OK"),
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HTTPHeaders({"Content-Length": "2"}),
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b"OK")
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self.connection.finish()
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router = CustomRouter()
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server = HTTPServer(router)
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The main responsibility of `Router` implementation is to provide a
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mapping from a request to `~.httputil.HTTPMessageDelegate` instance
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that will handle this request. In the example above we can see that
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routing is possible even without instantiating an `~.web.Application`.
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For routing to `~.web.RequestHandler` implementations we need an
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`~.web.Application` instance. `~.web.Application.get_handler_delegate`
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provides a convenient way to create `~.httputil.HTTPMessageDelegate`
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for a given request and `~.web.RequestHandler`.
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Here is a simple example of how we can we route to
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`~.web.RequestHandler` subclasses by HTTP method:
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.. code-block:: python
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resources = {}
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class GetResource(RequestHandler):
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def get(self, path):
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if path not in resources:
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raise HTTPError(404)
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self.finish(resources[path])
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class PostResource(RequestHandler):
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def post(self, path):
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resources[path] = self.request.body
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class HTTPMethodRouter(Router):
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def __init__(self, app):
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self.app = app
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def find_handler(self, request, **kwargs):
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handler = GetResource if request.method == "GET" else PostResource
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return self.app.get_handler_delegate(request, handler, path_args=[request.path])
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router = HTTPMethodRouter(Application())
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server = HTTPServer(router)
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`ReversibleRouter` interface adds the ability to distinguish between
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the routes and reverse them to the original urls using route's name
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and additional arguments. `~.web.Application` is itself an
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implementation of `ReversibleRouter` class.
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`RuleRouter` and `ReversibleRuleRouter` are implementations of
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`Router` and `ReversibleRouter` interfaces and can be used for
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creating rule-based routing configurations.
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Rules are instances of `Rule` class. They contain a `Matcher`, which
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provides the logic for determining whether the rule is a match for a
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particular request and a target, which can be one of the following.
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1) An instance of `~.httputil.HTTPServerConnectionDelegate`:
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.. code-block:: python
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router = RuleRouter([
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Rule(PathMatches("/handler"), ConnectionDelegate()),
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# ... more rules
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])
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class ConnectionDelegate(HTTPServerConnectionDelegate):
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def start_request(self, server_conn, request_conn):
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return MessageDelegate(request_conn)
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2) A callable accepting a single argument of `~.httputil.HTTPServerRequest` type:
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.. code-block:: python
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router = RuleRouter([
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Rule(PathMatches("/callable"), request_callable)
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])
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def request_callable(request):
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request.write(b"HTTP/1.1 200 OK\\r\\nContent-Length: 2\\r\\n\\r\\nOK")
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request.finish()
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3) Another `Router` instance:
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.. code-block:: python
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router = RuleRouter([
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Rule(PathMatches("/router.*"), CustomRouter())
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])
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Of course a nested `RuleRouter` or a `~.web.Application` is allowed:
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.. code-block:: python
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router = RuleRouter([
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Rule(HostMatches("example.com"), RuleRouter([
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Rule(PathMatches("/app1/.*"), Application([(r"/app1/handler", Handler)]))),
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]))
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])
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server = HTTPServer(router)
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In the example below `RuleRouter` is used to route between applications:
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.. code-block:: python
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app1 = Application([
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(r"/app1/handler", Handler1),
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# other handlers ...
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])
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app2 = Application([
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(r"/app2/handler", Handler2),
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# other handlers ...
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])
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router = RuleRouter([
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Rule(PathMatches("/app1.*"), app1),
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Rule(PathMatches("/app2.*"), app2)
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])
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server = HTTPServer(router)
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For more information on application-level routing see docs for `~.web.Application`.
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.. versionadded:: 4.5
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"""
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from __future__ import absolute_import, division, print_function
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import re
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from functools import partial
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from tornado import httputil
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from tornado.httpserver import _CallableAdapter
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from tornado.escape import url_escape, url_unescape, utf8
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from tornado.log import app_log
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from tornado.util import basestring_type, import_object, re_unescape, unicode_type
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try:
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import typing # noqa
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except ImportError:
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pass
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class Router(httputil.HTTPServerConnectionDelegate):
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"""Abstract router interface."""
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def find_handler(self, request, **kwargs):
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# type: (httputil.HTTPServerRequest, typing.Any)->httputil.HTTPMessageDelegate
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"""Must be implemented to return an appropriate instance of `~.httputil.HTTPMessageDelegate`
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that can serve the request.
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Routing implementations may pass additional kwargs to extend the routing logic.
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:arg httputil.HTTPServerRequest request: current HTTP request.
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:arg kwargs: additional keyword arguments passed by routing implementation.
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:returns: an instance of `~.httputil.HTTPMessageDelegate` that will be used to
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process the request.
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"""
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raise NotImplementedError()
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def start_request(self, server_conn, request_conn):
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return _RoutingDelegate(self, server_conn, request_conn)
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class ReversibleRouter(Router):
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"""Abstract router interface for routers that can handle named routes
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and support reversing them to original urls.
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"""
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def reverse_url(self, name, *args):
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"""Returns url string for a given route name and arguments
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or ``None`` if no match is found.
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:arg str name: route name.
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:arg args: url parameters.
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:returns: parametrized url string for a given route name (or ``None``).
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"""
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raise NotImplementedError()
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class _RoutingDelegate(httputil.HTTPMessageDelegate):
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def __init__(self, router, server_conn, request_conn):
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self.server_conn = server_conn
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self.request_conn = request_conn
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self.delegate = None
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self.router = router # type: Router
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def headers_received(self, start_line, headers):
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request = httputil.HTTPServerRequest(
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connection=self.request_conn,
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server_connection=self.server_conn,
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start_line=start_line, headers=headers)
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self.delegate = self.router.find_handler(request)
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if self.delegate is None:
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app_log.debug("Delegate for %s %s request not found",
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start_line.method, start_line.path)
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self.delegate = _DefaultMessageDelegate(self.request_conn)
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return self.delegate.headers_received(start_line, headers)
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def data_received(self, chunk):
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return self.delegate.data_received(chunk)
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def finish(self):
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self.delegate.finish()
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def on_connection_close(self):
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self.delegate.on_connection_close()
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class _DefaultMessageDelegate(httputil.HTTPMessageDelegate):
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def __init__(self, connection):
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self.connection = connection
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def finish(self):
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self.connection.write_headers(
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httputil.ResponseStartLine("HTTP/1.1", 404, "Not Found"), httputil.HTTPHeaders())
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self.connection.finish()
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class RuleRouter(Router):
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"""Rule-based router implementation."""
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def __init__(self, rules=None):
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"""Constructs a router from an ordered list of rules::
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RuleRouter([
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Rule(PathMatches("/handler"), Target),
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# ... more rules
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])
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You can also omit explicit `Rule` constructor and use tuples of arguments::
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RuleRouter([
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(PathMatches("/handler"), Target),
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])
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`PathMatches` is a default matcher, so the example above can be simplified::
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RuleRouter([
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("/handler", Target),
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])
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In the examples above, ``Target`` can be a nested `Router` instance, an instance of
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`~.httputil.HTTPServerConnectionDelegate` or an old-style callable,
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accepting a request argument.
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:arg rules: a list of `Rule` instances or tuples of `Rule`
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constructor arguments.
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"""
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self.rules = [] # type: typing.List[Rule]
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if rules:
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self.add_rules(rules)
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def add_rules(self, rules):
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"""Appends new rules to the router.
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:arg rules: a list of Rule instances (or tuples of arguments, which are
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passed to Rule constructor).
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"""
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for rule in rules:
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if isinstance(rule, (tuple, list)):
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assert len(rule) in (2, 3, 4)
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if isinstance(rule[0], basestring_type):
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rule = Rule(PathMatches(rule[0]), *rule[1:])
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else:
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rule = Rule(*rule)
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self.rules.append(self.process_rule(rule))
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def process_rule(self, rule):
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"""Override this method for additional preprocessing of each rule.
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:arg Rule rule: a rule to be processed.
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:returns: the same or modified Rule instance.
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"""
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return rule
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def find_handler(self, request, **kwargs):
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for rule in self.rules:
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target_params = rule.matcher.match(request)
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if target_params is not None:
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if rule.target_kwargs:
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target_params['target_kwargs'] = rule.target_kwargs
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delegate = self.get_target_delegate(
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rule.target, request, **target_params)
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if delegate is not None:
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return delegate
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return None
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def get_target_delegate(self, target, request, **target_params):
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"""Returns an instance of `~.httputil.HTTPMessageDelegate` for a
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Rule's target. This method is called by `~.find_handler` and can be
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extended to provide additional target types.
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:arg target: a Rule's target.
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:arg httputil.HTTPServerRequest request: current request.
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:arg target_params: additional parameters that can be useful
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for `~.httputil.HTTPMessageDelegate` creation.
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"""
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if isinstance(target, Router):
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return target.find_handler(request, **target_params)
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elif isinstance(target, httputil.HTTPServerConnectionDelegate):
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return target.start_request(request.server_connection, request.connection)
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elif callable(target):
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return _CallableAdapter(
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partial(target, **target_params), request.connection
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)
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return None
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class ReversibleRuleRouter(ReversibleRouter, RuleRouter):
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"""A rule-based router that implements ``reverse_url`` method.
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Each rule added to this router may have a ``name`` attribute that can be
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used to reconstruct an original uri. The actual reconstruction takes place
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in a rule's matcher (see `Matcher.reverse`).
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"""
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def __init__(self, rules=None):
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self.named_rules = {} # type: typing.Dict[str]
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super(ReversibleRuleRouter, self).__init__(rules)
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def process_rule(self, rule):
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rule = super(ReversibleRuleRouter, self).process_rule(rule)
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if rule.name:
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if rule.name in self.named_rules:
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app_log.warning(
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"Multiple handlers named %s; replacing previous value",
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rule.name)
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self.named_rules[rule.name] = rule
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return rule
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def reverse_url(self, name, *args):
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if name in self.named_rules:
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return self.named_rules[name].matcher.reverse(*args)
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for rule in self.rules:
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if isinstance(rule.target, ReversibleRouter):
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reversed_url = rule.target.reverse_url(name, *args)
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if reversed_url is not None:
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return reversed_url
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return None
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class Rule(object):
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"""A routing rule."""
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def __init__(self, matcher, target, target_kwargs=None, name=None):
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"""Constructs a Rule instance.
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:arg Matcher matcher: a `Matcher` instance used for determining
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whether the rule should be considered a match for a specific
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request.
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:arg target: a Rule's target (typically a ``RequestHandler`` or
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`~.httputil.HTTPServerConnectionDelegate` subclass or even a nested `Router`,
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depending on routing implementation).
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:arg dict target_kwargs: a dict of parameters that can be useful
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at the moment of target instantiation (for example, ``status_code``
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for a ``RequestHandler`` subclass). They end up in
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``target_params['target_kwargs']`` of `RuleRouter.get_target_delegate`
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method.
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:arg str name: the name of the rule that can be used to find it
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in `ReversibleRouter.reverse_url` implementation.
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"""
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if isinstance(target, str):
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# import the Module and instantiate the class
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# Must be a fully qualified name (module.ClassName)
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target = import_object(target)
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self.matcher = matcher # type: Matcher
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self.target = target
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self.target_kwargs = target_kwargs if target_kwargs else {}
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self.name = name
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def reverse(self, *args):
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return self.matcher.reverse(*args)
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def __repr__(self):
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return '%s(%r, %s, kwargs=%r, name=%r)' % \
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(self.__class__.__name__, self.matcher,
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self.target, self.target_kwargs, self.name)
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class Matcher(object):
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"""Represents a matcher for request features."""
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def match(self, request):
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"""Matches current instance against the request.
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:arg httputil.HTTPServerRequest request: current HTTP request
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:returns: a dict of parameters to be passed to the target handler
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(for example, ``handler_kwargs``, ``path_args``, ``path_kwargs``
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can be passed for proper `~.web.RequestHandler` instantiation).
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An empty dict is a valid (and common) return value to indicate a match
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when the argument-passing features are not used.
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``None`` must be returned to indicate that there is no match."""
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raise NotImplementedError()
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def reverse(self, *args):
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"""Reconstructs full url from matcher instance and additional arguments."""
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return None
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class AnyMatches(Matcher):
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"""Matches any request."""
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def match(self, request):
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return {}
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class HostMatches(Matcher):
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"""Matches requests from hosts specified by ``host_pattern`` regex."""
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def __init__(self, host_pattern):
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if isinstance(host_pattern, basestring_type):
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if not host_pattern.endswith("$"):
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host_pattern += "$"
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self.host_pattern = re.compile(host_pattern)
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else:
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self.host_pattern = host_pattern
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def match(self, request):
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if self.host_pattern.match(request.host_name):
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return {}
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return None
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class DefaultHostMatches(Matcher):
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"""Matches requests from host that is equal to application's default_host.
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Always returns no match if ``X-Real-Ip`` header is present.
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"""
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def __init__(self, application, host_pattern):
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self.application = application
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self.host_pattern = host_pattern
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def match(self, request):
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# Look for default host if not behind load balancer (for debugging)
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if "X-Real-Ip" not in request.headers:
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if self.host_pattern.match(self.application.default_host):
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return {}
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return None
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class PathMatches(Matcher):
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"""Matches requests with paths specified by ``path_pattern`` regex."""
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def __init__(self, path_pattern):
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if isinstance(path_pattern, basestring_type):
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if not path_pattern.endswith('$'):
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path_pattern += '$'
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self.regex = re.compile(path_pattern)
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else:
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self.regex = path_pattern
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assert len(self.regex.groupindex) in (0, self.regex.groups), \
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("groups in url regexes must either be all named or all "
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"positional: %r" % self.regex.pattern)
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self._path, self._group_count = self._find_groups()
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def match(self, request):
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match = self.regex.match(request.path)
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if match is None:
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return None
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if not self.regex.groups:
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return {}
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path_args, path_kwargs = [], {}
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# Pass matched groups to the handler. Since
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# match.groups() includes both named and
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# unnamed groups, we want to use either groups
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# or groupdict but not both.
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if self.regex.groupindex:
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path_kwargs = dict(
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(str(k), _unquote_or_none(v))
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for (k, v) in match.groupdict().items())
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else:
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path_args = [_unquote_or_none(s) for s in match.groups()]
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return dict(path_args=path_args, path_kwargs=path_kwargs)
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def reverse(self, *args):
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if self._path is None:
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raise ValueError("Cannot reverse url regex " + self.regex.pattern)
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assert len(args) == self._group_count, "required number of arguments " \
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|
"not found"
|
|
if not len(args):
|
|
return self._path
|
|
converted_args = []
|
|
for a in args:
|
|
if not isinstance(a, (unicode_type, bytes)):
|
|
a = str(a)
|
|
converted_args.append(url_escape(utf8(a), plus=False))
|
|
return self._path % tuple(converted_args)
|
|
|
|
def _find_groups(self):
|
|
"""Returns a tuple (reverse string, group count) for a url.
|
|
|
|
For example: Given the url pattern /([0-9]{4})/([a-z-]+)/, this method
|
|
would return ('/%s/%s/', 2).
|
|
"""
|
|
pattern = self.regex.pattern
|
|
if pattern.startswith('^'):
|
|
pattern = pattern[1:]
|
|
if pattern.endswith('$'):
|
|
pattern = pattern[:-1]
|
|
|
|
if self.regex.groups != pattern.count('('):
|
|
# The pattern is too complicated for our simplistic matching,
|
|
# so we can't support reversing it.
|
|
return None, None
|
|
|
|
pieces = []
|
|
for fragment in pattern.split('('):
|
|
if ')' in fragment:
|
|
paren_loc = fragment.index(')')
|
|
if paren_loc >= 0:
|
|
pieces.append('%s' + fragment[paren_loc + 1:])
|
|
else:
|
|
try:
|
|
unescaped_fragment = re_unescape(fragment)
|
|
except ValueError:
|
|
# If we can't unescape part of it, we can't
|
|
# reverse this url.
|
|
return (None, None)
|
|
pieces.append(unescaped_fragment)
|
|
|
|
return ''.join(pieces), self.regex.groups
|
|
|
|
|
|
class URLSpec(Rule):
|
|
"""Specifies mappings between URLs and handlers.
|
|
|
|
.. versionchanged: 4.5
|
|
`URLSpec` is now a subclass of a `Rule` with `PathMatches` matcher and is preserved for
|
|
backwards compatibility.
|
|
"""
|
|
def __init__(self, pattern, handler, kwargs=None, name=None):
|
|
"""Parameters:
|
|
|
|
* ``pattern``: Regular expression to be matched. Any capturing
|
|
groups in the regex will be passed in to the handler's
|
|
get/post/etc methods as arguments (by keyword if named, by
|
|
position if unnamed. Named and unnamed capturing groups
|
|
may not be mixed in the same rule).
|
|
|
|
* ``handler``: `~.web.RequestHandler` subclass to be invoked.
|
|
|
|
* ``kwargs`` (optional): A dictionary of additional arguments
|
|
to be passed to the handler's constructor.
|
|
|
|
* ``name`` (optional): A name for this handler. Used by
|
|
`~.web.Application.reverse_url`.
|
|
|
|
"""
|
|
super(URLSpec, self).__init__(PathMatches(pattern), handler, kwargs, name)
|
|
|
|
self.regex = self.matcher.regex
|
|
self.handler_class = self.target
|
|
self.kwargs = kwargs
|
|
|
|
def __repr__(self):
|
|
return '%s(%r, %s, kwargs=%r, name=%r)' % \
|
|
(self.__class__.__name__, self.regex.pattern,
|
|
self.handler_class, self.kwargs, self.name)
|
|
|
|
|
|
def _unquote_or_none(s):
|
|
"""None-safe wrapper around url_unescape to handle unmatched optional
|
|
groups correctly.
|
|
|
|
Note that args are passed as bytes so the handler can decide what
|
|
encoding to use.
|
|
"""
|
|
if s is None:
|
|
return s
|
|
return url_unescape(s, encoding=None, plus=False)
|