python - BeautifulSoup: get css classes from html

Question

Is there a way to get CSS classes from an HTML file using BeautifulSoup? Example snippet:

<style type="text/css">

 p.c3 {text-align: justify}

 p.c2 {text-align: left}

 p.c1 {text-align: center}

</style>

Perfect output would be:

cssdict = {
    'p.c3': {'text-align': 'justify'},
    'p.c2': {'text-align': 'left'},
    'p.c1': {'text-align': 'center'}
}

although something like this would do:

L = [
    ('p.c3', {'text-align': 'justify'}),  
    ('p.c2', {'text-align': 'left'}),    
    ('p.c1', {'text-align': 'center'})
]

Answer 1

BeautifulSoup itself doesn't parse CSS style declarations at all, but you can extract such sections then parse them with a dedicated CSS parser.

Depending on your needs, there are several CSS parsers available for python; I'd pick cssutils (requires python 2.5 or up (including python 3)), it is the most complete in it's support, and supports inline styles too.

Other options are css-py and tinycss.

To grab and parse such all style sections (example with cssutils):

import cssutils
sheets = []
for styletag in tree.findAll('style', type='text/css')
    if not styletag.string: # probably an external sheet
        continue
    sheets.append(cssutils.parseStyle(styletag.string))

With cssutil you can then combine these, resolve imports, and even have it fetch external stylesheets.