nkryptic/index-base.html

## gistfile1.rst

      
    Raw
  

              gistfile1.rst
            
          
    The expected output when rendering index.html is:
<!doctype html>
<head>
  <title>example</title>
</head>
<body>
  <h2>before</h2>
  <h2><span>start</span> <span>the middle</span> <span>end</span></h2>
  <h2>after</h2>
</body>
</html>

The expected output when rendering index2.html is:
<!doctype html>
<head>
  <title>example</title>
</head>
<body>
  <h2>before</h2>
  <h2>after</h2>
</body>
</html>

The expected output when rendering index3.html is:
<!doctype html>
<head>
  <title>example</title>
</head>
<body>
  <h2>before</h2>
  <h2><span>start</span> <span>right in</span> <span>the middle</span> <span>end</span></h2>
  <h2>after</h2>
</body>
</html>


## index-base.html
<!doctype html>
<head>
  <title>example</title>
</head>
<body>
  <h2>before</h2>
  {% load ifblock from myapp_tags %}
  {% ifblock middle %}
    <h2><span>start</span> {{ blockoutput }} <span>end</span></h2>
  {% endifblock %}
  <h2>after</h2>
</body>
</html>

## index.html
{% extends "index-base.html" %}
{% block middle %}<span>the middle</span>{% endblock %}

## index2.html
{% extends "index-base.html" %}

## index3.html
{% extends "index.html" %}
{% block middle %}<span>right in</span> {{ block.super }}{% endblock %}

## myapp_tags.py
from django.template import Library, TemplateSyntaxError
from django.template.loader_tags import BlockNode, BLOCK_CONTEXT_KEY

register = Library()


class IfBlockNode(BlockNode):

    def __repr__(self):
        return "<IfBlock Node: %s. Contents: %r>" % (self.name, self.nodelist)

    def render(self, context):
        block_context = context.render_context.get(BLOCK_CONTEXT_KEY)
        context.push()
        if block_context is None:
            result = ''
        else:
            push = block = block_context.pop(self.name)
            if block is None or block is self:
                result = ''
            else:
                context.push()
                # Create new block so we can store context without
                # thread-safety issues.
                block = IfBlockNode(block.name, block.nodelist)
                block.context = context
                context['block'] = block
                result = block.nodelist.render(context)
                context.pop()
                context['blockoutput'] = result
                result = self.nodelist.render(context)
            if push is not None:
                block_context.push(self.name, push)
        context.pop()
        return result

    def super(self):
        render_context = self.context.render_context
        if BLOCK_CONTEXT_KEY in render_context:
            block = render_context[BLOCK_CONTEXT_KEY].get_block(self.name)
            if block is not None and not isinstance(block, IfBlockNode):
                return super(IfBlockNode, self).render(self.context)
        return ''


@register.tag(name="ifblock")
def do_ifblock(parser, token):
    bits = token.contents.split()
    if len(bits) != 2:
        raise TemplateSyntaxError("'%s' tag takes only one argument" % bits[0])
    block_name = bits[1]
    # Keep track of the names of BlockNodes found in this template, so we can
    # check for duplication.
    try:
        if block_name in parser.__loaded_blocks:
            msg = "'%s' tag with name '%s' appears more than once"
            raise TemplateSyntaxError(msg % (bits[0], block_name))
        parser.__loaded_blocks.append(block_name)
    except AttributeError:  # parser.__loaded_blocks isn't a list yet
        parser.__loaded_blocks = [block_name]

    nodelist = parser.parse(('endifblock', 'endifblock %s' % block_name))
    parser.delete_first_token()
    return IfBlockNode(block_name, nodelist)
	<!doctype html>
	<head>
	<title>example</title>
	</head>
	<body>
	<h2>before</h2>
	{% load ifblock from myapp_tags %}
	{% ifblock middle %}
	<h2><span>start</span> {{ blockoutput }} <span>end</span></h2>
	{% endifblock %}
	<h2>after</h2>
	</body>
	</html>
	{% extends "index-base.html" %}
	{% block middle %}<span>the middle</span>{% endblock %}
	{% extends "index.html" %}
	{% block middle %}<span>right in</span> {{ block.super }}{% endblock %}
	from django.template import Library, TemplateSyntaxError
	from django.template.loader_tags import BlockNode, BLOCK_CONTEXT_KEY

	register = Library()


	class IfBlockNode(BlockNode):

	def __repr__(self):
	return "<IfBlock Node: %s. Contents: %r>" % (self.name, self.nodelist)

	def render(self, context):
	block_context = context.render_context.get(BLOCK_CONTEXT_KEY)
	context.push()
	if block_context is None:
	result = ''
	else:
	push = block = block_context.pop(self.name)
	if block is None or block is self:
	result = ''
	else:
	context.push()
	# Create new block so we can store context without
	# thread-safety issues.
	block = IfBlockNode(block.name, block.nodelist)
	block.context = context
	context['block'] = block
	result = block.nodelist.render(context)
	context.pop()
	context['blockoutput'] = result
	result = self.nodelist.render(context)
	if push is not None:
	block_context.push(self.name, push)
	context.pop()
	return result

	def super(self):
	render_context = self.context.render_context
	if BLOCK_CONTEXT_KEY in render_context:
	block = render_context[BLOCK_CONTEXT_KEY].get_block(self.name)
	if block is not None and not isinstance(block, IfBlockNode):
	return super(IfBlockNode, self).render(self.context)
	return ''


	@register.tag(name="ifblock")
	def do_ifblock(parser, token):
	bits = token.contents.split()
	if len(bits) != 2:
	raise TemplateSyntaxError("'%s' tag takes only one argument" % bits[0])
	block_name = bits[1]
	# Keep track of the names of BlockNodes found in this template, so we can
	# check for duplication.
	try:
	if block_name in parser.__loaded_blocks:
	msg = "'%s' tag with name '%s' appears more than once"
	raise TemplateSyntaxError(msg % (bits[0], block_name))
	parser.__loaded_blocks.append(block_name)
	except AttributeError: # parser.__loaded_blocks isn't a list yet
	parser.__loaded_blocks = [block_name]

	nodelist = parser.parse(('endifblock', 'endifblock %s' % block_name))
	parser.delete_first_token()
	return IfBlockNode(block_name, nodelist)