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

   1 # Copyright 2015 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4
   5 import posixpath
   6
   7 from environment import GetAppVersion
   8 from future import Future
   9 from urllib import urlencode
  10 from urlparse import urlparse, parse_qs
  11
  12 def _MakeHeaders(headers={}):
  13   headers['User-Agent'] = 'Chromium-Docserver/%s' % GetAppVersion()
  14   headers['Cache-Control'] = 'max-age=0'
  15   return headers
  16
  17
  18 def _AddQueryToUrl(url, new_query):
  19   """Adds query paramters to a URL. This merges the given set of query params
  20   with any that were already a part of the URL.
  21   """
  22   parsed_url = urlparse(url)
  23   query = parse_qs(parsed_url.query)
  24   query.update(new_query)
  25   query_string = urlencode(query, True)
  26   return '%s://%s%s?%s#%s' % (parsed_url.scheme, parsed_url.netloc,
  27       parsed_url.path, query_string, parsed_url.fragment)
  28
  29
  30 class UrlFetcher(object):
  31   def __init__(self):
  32     self._base_path = None
  33
  34   def SetBasePath(self, base_path):
  35     assert base_path is None or not base_path.endswith('/'), base_path
  36     self._base_path = base_path
  37
  38   def Fetch(self, url, headers={}, query={}):
  39     return self.FetchImpl(_AddQueryToUrl(self._FromBasePath(url), query),
  40         _MakeHeaders(headers))
  41
  42   def FetchAsync(self, url, headers={}, query={}):
  43     return self.FetchAsyncImpl(_AddQueryToUrl(self._FromBasePath(url), query),
  44         _MakeHeaders(headers))
  45
  46   def FetchImpl(self, url, headers):
  47     """Fetches a URL synchronously.
  48     """
  49     raise NotImplementedError(self.__class__)
  50
  51   def FetchAsyncImpl(self, url, headers):
  52     """Fetches a URL asynchronously and returns a Future with the result.
  53     """
  54     raise NotImplementedError(self.__class__)
  55
  56   def _FromBasePath(self, url):
  57     assert not url.startswith('/'), url
  58     if self._base_path is not None:
  59       url = posixpath.join(self._base_path, url) if url else self._base_path
  60     return url