Docserver: Implement the content providers infrastructure, where a

chrome/common/extensions/docs/server2/content_provider.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.
+
+from HTMLParser import HTMLParser
+import mimetypes
+import logging
+import os
+
+from compiled_file_system import SingleFile
+from directory_zipper import DirectoryZipper
+from file_system import ToUnicode
+from future import Gettable, Future
+from third_party.handlebar import Handlebar
+
+
+class ContentAndType(object):
+  '''Return value from ContentProvider.GetContentAndType.
+  '''
+
+  def __init__(self, content, content_type):
+    self.content = content
+    self.content_type = content_type
+
+
+class ContentProvider(object):
+  '''Returns file contents correctly typed for their content-types (in the HTTP
+  sense). Content-type is determined from Python's mimetype library which
+  guesses based on the file extension.
+
+  Typically the file contents will be either str (for binary content) or
+  unicode (for text content). However, HTML files *may* be returned as
+  Handlebar templates (if supports_templates is True on construction), in which
+  case the caller will presumably want to Render them.
+  '''
+
+  def __init__(self,
+               name,
+               compiled_fs_factory,
+               file_system,
+               supports_templates=False,
+               supports_zip=False):
+    # Public.
+    self.name = name
+    self.file_system = file_system
+    # Private.
+    self._content_cache = compiled_fs_factory.Create(file_system,
+                                                     self._CompileContent,
+                                                     ContentProvider)
+    self._supports_templates = supports_templates
+    if supports_zip:
+      self._directory_zipper = DirectoryZipper(compiled_fs_factory, file_system)
+    else:
+      self._directory_zipper = None
+
+  @SingleFile
+  def _CompileContent(self, path, text):
+    assert text is not None, path
+    mimetype = mimetypes.guess_type(path)[0]
+    if mimetype is None:
+      content = text
+      mimetype = 'text/plain'
+    elif mimetype == 'text/html':
+      content = ToUnicode(text)
+      if self._supports_templates:
+        content = Handlebar(content)
+    elif (mimetype.startswith('text/') or
+          mimetype in ('application/javascript', 'application/json')):
+      content = ToUnicode(text)
+    else:
+      content = text
+    return ContentAndType(content, mimetype)
+
+  def GetContentAndType(self, host, path):
+    path = path.lstrip('/')
+    base, ext = os.path.splitext(path)
+
+    # Check for a zip file first, if zip is enabled.
+    if self._directory_zipper and ext == '.zip':
+      zip_future = self._directory_zipper.Zip(base)
+      return Future(delegate=Gettable(
+          lambda: ContentAndType(zip_future.Get(), 'application/zip')))
+
+    return self._content_cache.GetFromFile(path, binary=True)
+
+  def Cron(self):
+    # TODO(kalman): Implement.
+    pass