Enables attribute list support for lists in Python Markdown.

attr_list.py

# -*- coding: utf-8 -*-

from __future__ import unicode_literals

import re

from markdown.extensions import Extension
from markdown.extensions.attr_list import AttrListTreeprocessor as _AttrListTreeprocessor, isheader
from markdown.util import isBlockLevel


class AttrListExtension(Extension):
    def extendMarkdown(self, md, md_globals):
        md.treeprocessors.add('attr_list', AttrListTreeprocessor(md), '>prettify')

class AttrListTreeprocessor(_AttrListTreeprocessor):
    BASE_RE = r'\{\:([^\}]*)\}'
    PARENT_RE = r'\{\^([^\}]*)\}'
    HEADER_RE = re.compile(r'[ ]+%s[ ]*$' % BASE_RE)
    BLOCK_RE = re.compile(r'\n[ ]*%s[ ]*$' % BASE_RE)
    LIST_RE = re.compile(r'\n[ ]*%s[ ]*$' % PARENT_RE)
    INLINE_RE = re.compile(r'^%s' % BASE_RE)
    
    
    def _get_last_child(self, elem):
        if len(elem):
            return self._get_last_child(elem[-1])
        
        return elem
    
    def _is_list(self, elem):
        return elem.tag in ['dl', 'ol', 'ul']
    
    
    def run(self, doc):
        for elem in doc.getiterator():
            if isBlockLevel(elem.tag):
                if self._is_list(elem):
                    lc = self._get_last_child(elem)
                    attr = None
                    
                    if lc.tail.strip():
                        attr = 'tail'
                    elif lc.text.strip():
                        attr = 'text'
                    
                    if attr:
                        text = getattr(lc, attr)
                        
                        m = self.LIST_RE.search(text)
                        
                        if m:
                            self.assign_attrs(elem, m.group(1))
                            setattr(lc, attr, text[:m.start()])
                    
                    continue
                
                # Block level: check for attrs on last line of text
                RE = self.BLOCK_RE
                
                if isheader(elem) or elem.tag == 'dt':
                    # header or def-term: check for attrs at end of line
                    RE = self.HEADER_RE
                
                if len(elem) and elem.tag == 'li':
                    # special case list items. children may include a ul or ol.
                    pos = None
                    # find the ul or ol position
                    for i, child in enumerate(elem):
                        if child.tag in ['ul', 'ol']:
                            pos = i
                            
                            break
                    
                    if pos is None and elem[-1].tail:
                        # use tail of last child. no ul or ol.
                        m = RE.search(elem[-1].tail)
                        
                        if m:
                            self.assign_attrs(elem, m.group(1))
                            elem[-1].tail = elem[-1].tail[:m.start()]
                    elif pos is not None and pos > 0 and elem[pos-1].tail:
                        # use tail of last child before ul or ol
                        m = RE.search(elem[pos-1].tail)
                        
                        if m:
                            self.assign_attrs(elem, m.group(1))
                            elem[pos-1].tail = elem[pos-1].tail[:m.start()]
                    elif elem.text:
                        # use text. ul is first child.
                        m = RE.search(elem.text)
                        
                        if m:
                            self.assign_attrs(elem, m.group(1))
                            elem.text = elem.text[:m.start()]
                elif len(elem) and elem[-1].tail:
                    # has children. Get from tail of last child
                    m = RE.search(elem[-1].tail)
                    
                    if m:
                        self.assign_attrs(elem, m.group(1))
                        elem[-1].tail = elem[-1].tail[:m.start()]
                        
                        if isheader(elem):
                            # clean up trailing #s
                            elem[-1].tail = elem[-1].tail.rstrip('#').rstrip()
                elif elem.text:
                    # no children. Get from text.
                    m = RE.search(elem.text)
                    
                    if m:
                        self.assign_attrs(elem, m.group(1))
                        elem.text = elem.text[:m.start()]
                        
                        if isheader(elem):
                            # clean up trailing #s
                            elem.text = elem.text.rstrip('#').rstrip()
            else:
                # inline: check for attrs at start of tail
                if elem.tail:
                    m = self.INLINE_RE.match(elem.tail)
                    
                    if m:
                        self.assign_attrs(elem, m.group(1))
                        elem.tail = elem.tail[m.end():]

def makeExtension(configs = None):
    if configs is None:
        configs = {}
    
    return AttrListExtension(configs)

I found a bug, lc.tail is null on line 42 for mardown like this:

1. Apple
1. (Banana)[#pear]

Here is a fix.