Docserver: there is only one.

chrome/common/extensions/docs/server2/path_canonicalizer.py

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import logging
 import os
+import posixpath
+import traceback
+
+from branch_utility import BranchUtility
+from file_system import FileNotFoundError
 from third_party.json_schema_compiler.model import UnixName
 import svn_constants
 
+def _SimplifyFileName(file_name):
+  return (posixpath.splitext(file_name)[0]
+      .lower()
+      .replace('.', '')
+      .replace('-', '')
+      .replace('_', ''))
+
 class PathCanonicalizer(object):
   '''Transforms paths into their canonical forms. Since the dev server has had
   many incarnations - e.g. there didn't use to be apps/ - there may be old
   paths lying around the webs. We try to redirect those to where they are now.
   '''
-  def __init__(self, channel, compiled_fs_factory):
-    self._channel = channel
-    self._identity_fs = compiled_fs_factory.CreateIdentity(PathCanonicalizer)
+  def __init__(self, compiled_fs_factory):
+    # Map of simplified API names (for typo detection) to their real paths.
+    def make_public_apis(_, file_names):
+      return {_SimplifyFileName(name): name for name in file_names}

[cduvall, 2013/05/15 00:50:50]

use dict((...

[not at google - send to devlin, 2013/05/15 01:26:50]

Done.

+    self._public_apis = compiled_fs_factory.Create(make_public_apis,
+                                                   PathCanonicalizer)
 
   def Canonicalize(self, path):
-    starts_with_channel, path_without_channel = (False, path)
-    if path.startswith('%s/' % self._channel):
-      starts_with_channel, path_without_channel = (
-          True, path[len(self._channel) + 1:])
+    '''Returns the canonical path for |path|, and whether that path is a
+    permanent canonicalisation (e.g. when we redirect from a channel to a
+    channel-less URL) or temporary (e.g. when we redirect from an apps-only API
+    to an extensions one - we may at some point enable it for extensions).
+    '''
+    class ReturnType(object):
+      def __init__(self, path, permanent):
+        self.path = path
+        self.permanent = permanent
+      # Catch incorrect comparisons by disabling ==/!=.
+      def __eq__(self): raise NotImplementedError()

[cduvall, 2013/05/15 00:50:50]

these need to take another argument or you get a TypeError instead of the
NotImplementedError.

[not at google - send to devlin, 2013/05/15 01:26:50]

ah. thanks.

+      def __ne__(self): raise NotImplementedError()
 
-    if any(path.startswith(prefix)
-           for prefix in ('extensions/', 'apps/', 'static/')):
-      return path
+    # Strip any channel info off it. There are no channels anymore.
+    for channel_name in BranchUtility.GetAllChannelNames():
+      channel_prefix = channel_name + '/'
+      if path.startswith(channel_prefix):
+        # Redirect now so that we can set the permanent-redirect bit.  Channel
+        # redirects are the only things that should be permanent redirects;
+        # anything else *could* change, so is temporary.
+        return ReturnType(path[len(channel_prefix):], True)
 
-    if '/' in path_without_channel or path_without_channel == '404.html':
-      return path
+    # No further work needed for static.
+    if path.startswith('static/'):
+      return ReturnType(path, False)
 
-    apps_templates = self._identity_fs.GetFromFileListing(
-        '/'.join((svn_constants.PUBLIC_TEMPLATE_PATH, 'apps')))
-    extensions_templates = self._identity_fs.GetFromFileListing(
-        '/'.join((svn_constants.PUBLIC_TEMPLATE_PATH, 'extensions')))
+    # People go to just "extensions" or "apps". Redirect to the directory.
+    if path in ('extensions', 'apps'):
+      return ReturnType(path + '/', False)
 
-    if self._channel is None or not starts_with_channel:
-      apps_path = 'apps/%s' % path_without_channel
-      extensions_path = 'extensions/%s' % path_without_channel
+    # The rest of this function deals with trying to figure out what API page
+    # for extensions/apps to redirect to, if any. We see a few different cases
+    # here:
+    #  - Unqualified names ("browserAction.html"). These are easy to resolve;
+    #    figure out whether it's an extension or app API and redirect.
+    #     - but what if it's both? Well, assume extensions. Maybe later we can
+    #       check analytics and see which is more popular.
+    #  - Wrong names ("apps/browserAction.html"). This really does happen,
+    #    damn it, so do the above logic but record which is the default.
+    if any(path.startswith(prefix) for prefix in ('extensions/', 'apps/')):

[cduvall, 2013/05/15 00:50:50]

i believe you can do:
path.startswith(('extensions/', 'apps/'))

[not at google - send to devlin, 2013/05/15 01:26:50]

Done.

+      default_platform, reference_path = path.split('/', 1)
     else:
-      apps_path = '%s/apps/%s' % (self._channel, path_without_channel)
-      extensions_path = '%s/extensions/%s' % (self._channel,
-                                              path_without_channel)
+      default_platform, reference_path = ('extensions', path)
 
-    unix_path = UnixName(os.path.splitext(path_without_channel)[0])
-    if unix_path in extensions_templates:
-      return extensions_path
-    if unix_path in apps_templates:
-      return apps_path
-    return extensions_path
+    try:
+      apps_public = self._public_apis.GetFromFileListing(
+          '/'.join((svn_constants.PUBLIC_TEMPLATE_PATH, 'apps')))
+      extensions_public = self._public_apis.GetFromFileListing(
+          '/'.join((svn_constants.PUBLIC_TEMPLATE_PATH, 'extensions')))
+    except FileNotFoundError:
+      # Probably offline.
+      logging.warning(traceback.format_exc())
+      return ReturnType(path, False)
+
+    simple_reference_path = _SimplifyFileName(reference_path)
+    apps_path = apps_public.get(simple_reference_path)
+    extensions_path = extensions_public.get(simple_reference_path)
+
+    if apps_path is None:
+      if extensions_path is None:
+        # No idea. Just return the original path. It'll probably 404.
+        pass
+      else:
+        path = 'extensions/%s' % extensions_path
+    else:
+      if extensions_path is None:
+        path = 'apps/%s' % apps_path
+      else:
+        assert apps_path == extensions_path
+        path = '%s/%s' % (default_platform, apps_path)
+
+    return ReturnType(path, False)