Fixed #7318 -- Cleaned up the template inheritance logic, specifically to handle the case where the parent template has no template tags/blocks. Took the opportunity to optimize the logic a little. Thanks to Matthias Kestenholz <mk@spinlock.ch> for the original report and test case.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@7688 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/template/loader_tags.py

@@ -69,10 +69,6 @@ class ExtendsNode(Node):
 
     def render(self, context):
         compiled_parent = self.get_parent(context)
-        pos = 0
-        while isinstance(compiled_parent.nodelist[pos], TextNode):
-            pos += 1
-        parent_is_child = isinstance(compiled_parent.nodelist[pos], ExtendsNode)
         parent_blocks = dict([(n.name, n) for n in compiled_parent.nodelist.get_nodes_by_type(BlockNode)])
         for block_node in self.nodelist.get_nodes_by_type(BlockNode):
             # Check for a BlockNode with this node's name, and replace it if found.
@@ -83,8 +79,16 @@ class ExtendsNode(Node):
                 # parent block might be defined in the parent's *parent*, so we
                 # add this BlockNode to the parent's ExtendsNode nodelist, so
                 # it'll be checked when the parent node's render() is called.
-                if parent_is_child:
-                    compiled_parent.nodelist[pos].nodelist.append(block_node)
+
+                # Find out if the parent template has a parent itself
+                for node in compiled_parent.nodelist:
+                    if not isinstance(node, TextNode):
+                        # If the first non-text node is an extends, handle it.
+                        if isinstance(node, ExtendsNode):
+                            node.nodelist.append(block_node)
+                        # Extends must be the first non-text node, so once you find
+                        # the first non-text node you can stop looking. 
+                        break
             else:
                 # Keep any existing parents and add a new one. Used by BlockNode.
                 parent_block.parent = block_node.parent

tests/regressiontests/templates/tests.py

@@ -704,6 +704,12 @@ class Templates(unittest.TestCase):
             # Inheritance from local context with variable parent template
             'inheritance25': ("{% extends context_template.1 %}{% block first %}2{% endblock %}{% block second %}4{% endblock %}", {'context_template': [template.Template("Wrong"), template.Template("1{% block first %}_{% endblock %}3{% block second %}_{% endblock %}")]}, '1234'),
 
+            # Set up a base template to extend
+         	'inheritance26': ("no tags", {}, 'no tags'),
+
+         	# Inheritance from a template that doesn't have any blocks
+         	'inheritance27': ("{% extends 'inheritance26' %}", {}, 'no tags'),
+         	
             ### I18N ##################################################################
 
             # {% spaceless %} tag