Issue 3092 - Support use of Jinja2 template inheritance

cms/utils.py

 # coding: utf-8
 
 # This file is part of the Adblock Plus web scripts,
 # Copyright (C) 2006-2015 Eyeo GmbH
 #
 # Adblock Plus is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 3 as
 # published by the Free Software Foundation.
 #
 # Adblock Plus is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
 # along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
 
+import re
+
 from cms.converters import converters, TemplateConverter
 
 def get_page_params(source, locale, page, format=None, site_url_override=None,
                     localized_string_callback=None):
   # Guess page format if omitted, but default to Markdown for friendlier exceptions
   if format is None:
     for format in converters.iterkeys():
       if source.has_page(page, format):
         break
     else:
       format = "md"
 
   params = {
     "source": source,
     "template": "default",
     "locale": locale,
     "page": page,
     "pagedata": source.read_page(page, format),
     "config": source.read_config(),
     "localized_string_callback": localized_string_callback,
+    "jinja2_inheritence": False
   }
 
   localefile = page
   if params["config"].has_option("locale_overrides", page):
     localefile = params["config"].get("locale_overrides", page)
   params["localedata"] = source.read_locale(params["locale"], localefile)
 
   if params["config"].has_option("general", "siteurl"):
     if site_url_override:
       params["site_url"] = site_url_override
     else:
       params["site_url"] = params["config"].get("general", "siteurl")
 
   try:
     converter = converters[format](params)
   except KeyError:
     raise Exception("Page %s uses unknown format %s" % (page, format))
 
-  # Note: The converter might change some parameters so we can only read in
-  # template data here.
-  params["templatedata"] = source.read_template(params["template"])
+  if format == "tmpl" and re.search(r"{%\s*extends.+?%}", params["pagedata"][0]):
+    params["jinja2_inheritence"] = True
+  else:
+    # Note: The converter might change some parameters so we can only read in
+    # template data here.
+    params["templatedata"] = source.read_template(params["template"])
 
   defaultlocale = params["config"].get("general", "defaultlocale")
   params["defaultlocale"] = defaultlocale
 
   locales = [
     l
     for l in source.list_locales()
     if source.has_locale(l, localefile)
   ]
   if defaultlocale not in locales:
     locales.append(defaultlocale)
   locales.sort()
   params["available_locales"] = locales
 
-  params["head"], params["body"] = converter()
+  if params["jinja2_inheritence"]:
+    params["body"] = converter()
+  else:
+    params["head"], params["body"] = converter()
+
   if converter.total_translations > 0:
     params["translation_ratio"] = (1 -
         float(converter.missing_translations) / converter.total_translations)
   else:
     params["translation_ratio"] = 1
 
   return params
 
 def process_page(source, locale, page, format=None, site_url_override=None,
                  localized_string_callback=None):
-  return TemplateConverter(
-    get_page_params(source, locale, page, format,
-                    site_url_override, localized_string_callback),
-    key="templatedata"
-  )()
+  page_params = get_page_params(source, locale, page, format,
+                                site_url_override, localized_string_callback)
+
+  if page_params["jinja2_inheritence"]:
+    return page_params["body"]
+  else:
+    return TemplateConverter(
+      page_params,
+      key="templatedata"
+    )()