Refactor the devserver to make it easier to control caching

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
+from third_party.json_schema_compiler.model import UnixName
+import svn_constants
+
+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.GetOrCreateIdentity()
+
+  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:])
+
+    if any(path.startswith(prefix)
+           for prefix in ('extensions/', 'apps/', 'static/')):
+      return path
+
+    if '/' in path_without_channel or path_without_channel == '404.html':
+      return path
+
+    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')))
+
+    if self._channel is None or not starts_with_channel:
+      apps_path = 'apps/%s' % path_without_channel
+      extensions_path = 'extensions/%s' % path_without_channel
+    else:
+      apps_path = '%s/apps/%s' % (self._channel, path_without_channel)
+      extensions_path = '%s/extensions/%s' % (self._channel,
+                                              path_without_channel)
+
+    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