Markup twitter hashtags and usernames within a html fragment

twitter-html-transform.py

#!/usr/bin/env python
"""
The twitter-text-python library (https://pypi.python.org/pypi/twitter-text-python) can be used
to urlify text containing @<username>s and #<hashtag>s. It is a bit trickier if you want to do
the same with HTML, but BeautifulSoup makes it straightforward.
"""
from bs4 import BeautifulSoup, NavigableString
from ttp import ttp

parse_text = ttp.Parser().parse

#non-exhaustive list of tags you want to leave as is
EXCLUDE_TAGS = frozenset(['a', 'style', 'script', 'title', 'link'])

def transform_html(html):
    """Markup twitter hashtags and usernames within a html fragment

    >>> fragment = '<p>my name is @SorenKQuotes and my site is <a href="http://site.com/index.html#link">here</a></p>'
    >>> for a in BeautifulSoup(fragment).findAll('a'):
    ...     print(a)
    <a href="http://site.com/index.html#link">here</a>

    >>> fragment = transform_html(fragment)

    >>> for a in BeautifulSoup(fragment).findAll('a'):
    ...     print(a)
    <a href="https://twitter.com/SorenKQuotes">@SorenKQuotes</a>
    <a href="http://site.com/index.html#link">here</a>
    """
    soup = BeautifulSoup(html)
    for tag in soup.findAll():
        if tag.name.lower() in EXCLUDE_TAGS:
            continue
        for child in tag.contents:
            if isinstance(child, NavigableString):
                child.replace_with(
                    BeautifulSoup(parse_text(child).html)
                )
    return unicode(soup)


if __name__ == '__main__':
    import doctest
    doctest.testmod()