Question

I want to parse this CSS Selector (and others of a similar form):
div.class1#myid.class2[key=value]

and have it match “.class1” and “.class2” but I can’t figure out what regex to use..

example: http://www.rubular.com/r/3dxpzyJLeK

In an ideal world, I’d also want to extract the:

• type (i.e. div)
• class (i.e. a list of classes)
• id (i.e myid)
• key (i.e. key)
• operator (i.e. =)
• value (i.e. value)

but I can’t get the basics going!

Any help would be massively appreciated 🙂

Thanks!

Answer 1

Thanks all very much for your suggestions and help. I tied it all together into the following two Regex Patterns:

This one parses the CSS selector string (e.g. div#myid.myclass[attr=1,fred=3]) http://www.rubular.com/r/2L0N5iWPEJ

cssSelector = re.compile(r'^(?P<type>[\*|\w|\-]+)?(?P<id>#[\w|\-]+)?(?P<classes>\.[\w|\-|\.]+)*(?P<data>\[.+\])*$')

>>> cssSelector.match("table#john.test.test2[hello]").groups()
('table', '#john', '.test.test2', '[hello]')
>>> cssSelector.match("table").groups()
('table', None, None, None)
>>> cssSelector.match("table#john").groups()
('table', '#john', None, None)
>>> cssSelector.match("table.test.test2[hello]").groups()
('table', None, '.test.test2', '[hello]')
>>> cssSelector.match("table#john.test.test2").groups()
('table', '#john', '.test.test2', None)
>>> cssSelector.match("*#john.test.test2[hello]").groups()
('*', '#john', '.test.test2', '[hello]')
>>> cssSelector.match("*").groups()
('*', None, None, None)

And this one does the attributes (e.g. [link,key~=value]) http://www.rubular.com/r/2L0N5iWPEJ:

attribSelector = re.compile(r'(?P<word>\w+)\s*(?P<operator>[^\w\,]{0,2})\s*(?P<value>\w+)?\s*[\,|\]]')

>>> a = attribSelector.findall("[link, ds9 != test, bsdfsdf]")
>>> for x in a: print x
('link', '', '')
('ds9', '!=', 'test')
('bsdfsdf', '', '')

A couple of things to note:
1) This parses attributes using comma delimitation (since I am not using strict CSS).
2) This requires patterns take the format: tag, id, classes, attributes

The first regex does tokens, so the whitespace and ‘>’ separated parts of a selector string. This is because I wanted to use it to check against my own object graph 🙂

Thanks again!