tmb and div nodes

tags.py

from django import template

register = template.Library()

class ParseClassesNode(template.Node):
    def parse_until(self, parser, token, end):
        contents = token.split_contents()
        self.classes = ' '.join(contents[1:])
        self.nodelist = parser.parse((end,))
        parser.delete_first_token()

class TmbNode(ParseClassesNode):
    def __init__(self, parser, token):
        self.parse_until(parser, token, 'endtmb')

    def render(self, context):
        top_contents = []
        bottom_contents = []
        middle_contents = []
        for node in self.nodelist:
            if isinstance(node, DivNode) and node.classes == 'top':
                top_contents.append(node.render(context))
            elif isinstance(node, DivNode) and node.classes == 'bottom':
                bottom_contents.append(node.render(context))
            else:
                middle_contents.append(node.render(context))
        if not top_contents:
            top_contents = ['<div class="top"/>']
        if not bottom_contents:
            bottom_contents = ['<div class="bottom"/>']

        return '<div class="%s">%s</div>' % (self.classes, ''.join(top_contents + middle_contents + bottom_contents))

class DivNode(ParseClassesNode):
    def __init__(self, parser, token):
        self.parse_until(parser, token, 'enddiv')

    def render(self, context):
        contents = self.nodelist.render(context)
        return '<div class="%s">%s</div>' % (self.classes, contents)

register.tag('tmb', TmbNode)
register.tag('div', DivNode)