Issue 3092 - Support use of Jinja2 template inheritance

cms/utils.py

Index: cms/utils.py
diff --git a/cms/utils.py b/cms/utils.py
index 66d8498f74582a93b1fff3ccac87879d2877654b..9199e322d9fa942ddeb97e6f93cb018739edeaaa 100644
--- a/cms/utils.py
+++ b/cms/utils.py
@@ -15,6 +15,8 @@
 # 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,
@@ -35,6 +37,7 @@ def get_page_params(source, locale, page, format=None, site_url_override=None,
     "pagedata": source.read_page(page, format),
     "config": source.read_config(),
     "localized_string_callback": localized_string_callback,
+    "jinja2_inheritence": False
   }
 
   localefile = page
@@ -53,9 +56,12 @@ def get_page_params(source, locale, page, format=None, site_url_override=None,
   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
@@ -70,7 +76,11 @@ def get_page_params(source, locale, page, format=None, site_url_override=None,
   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)
@@ -81,8 +91,13 @@ def get_page_params(source, locale, page, format=None, site_url_override=None,
 
 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"
+    )()