#!/usr/bin/env python

import re

p_emphasis = ur'(?<!\\)\*(\S.*?)(?<!\s)\*'
p_paragraph = ur'\A(?=\S)|(?<=\A\n)(?=\S)|(?<=\n\n)(?=\S)'
p_link = ur'(?s)(?<!\\)\*([^*]+)\*(\W?)(?:[^\S\n]+|\n(?!\n))+(\S*[./]\S+)'

r_link = re.compile(p_link)
r_emphasis = re.compile(p_emphasis)
r_paragraph = re.compile(p_paragraph)

def s_link(match): 
   text, punctuation, link = match.groups()
   if not ':' in link: link = 'http://' + link
   return '<a href="%s">%s</a>%s' % (link, text, punctuation)

def hypertext(text): 
   text = text.replace('<', '&lt;')
   text = r_link.sub(s_link, text)
   text = r_emphasis.sub(r'<strong>\g<1></strong>', text)
   text = r_paragraph.sub('<p>', text)
   text = text.replace(' \\n\n', '<br>\n')
   return text.replace('\\*', '*')

example = """
The *commonly used* http://example.org/ example domains *changed recently*,
tech.slashdot.org/story/11/01/30/1823241/Examplecom-Has-Changed and now
redirect to an *IANA page* www.iana.org/domains/example/ instead. The IANA is
operated by *ICANN*. icann.org

*[ICANN Logo]* inamidst.com/stuff/2011/icann

*The ICANN Logo*
"""

if __name__ == '__main__': 
   print hypertext(example)