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I've got a bunch of HTML pages, in which I'd like to convert CSS-formatted text snippets into standard HTML tags. e.g <span class="bold">some text</span> will become <b>some text</b>

I'm stuck at nested span fragments:

<span class="italic"><span class="bold">XXXXXXXX</span></span>
<span class="italic">some text<span class="bold">nested text<span class="underline">deep nested text</span></span></span>

I'd like to convert the fragment using Python's regex library. What would be the optimal strategy to regex search-&-replace the above input?

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1  
Why must it be done by regular expression? –  hwnd 2 days ago
 
It's just a personal preference. I know it could be done with recusive plain string search... But somehow I find regex solutions to be more elegant... –  user1656343 2 days ago
2  
The optimal strategy would really be to use something other than regular expressions, which are terribly underpowered for this. Beautiful Soup is the most popular go-to solution for parsing HTML in Python. –  qwrrty 2 days ago
 
It probably won't be so elegant. To do tag balancing, you need something stronger than regex. If you still want to use regular expressions, you'll need to use a loop. –  Michael 2 days ago
1  
The ultimate html-regex rant is here. –  John1024 2 days ago
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1 Answer

up vote 1 down vote

My solution using lxml and cssselect and a bit of Python:

#!/usr/bin/env python

import cssselect  # noqa
from lxml.html import fromstring


html = """
<span class="italic"><span class="bold">XXXXXXXX</span></span>
<span class="italic">some text<span class="bold">nested text<span class="underline">deep nested text</span></span></span>
"""

class_to_style = {
    "underline": "u",
    "italic": "i",
    "bold": "b",
}

output = []
doc = fromstring(html)
spans = doc.cssselect("span")
for span in spans:
    if span.attrib.get("class"):
        output.append("<{0}>{1}</{0}>".format(class_to_style[span.attrib["class"]], span.text or ""))
print "".join(output)

Output:

<i></i><b>XXXXXXXX</b><i>some text</i><b>nested text</b><u>deep nested text</u>

NB: This is a naive solution and does not produce the correct output as you'd have to keep a queue of open tags and close them at the end.

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1  
Awesome! I was unaware of cssselect until now! Thanks @James Mills ! –  user1656343 yesterday
 
Welcome I use it quite a lot in my work :) pypi.python.org/pypi/spyda –  James Mills yesterday
 
Oops! It doesn't work as expected.. the output should be: <i><b>XXXXXXXX</b></i><i>some text<b>nested text<u>deep nested text</b></u></i> –  user1656343 yesterday
 
Yes my solution is naive at best. You'll have to keep a queue of open tags and close them at the end. I'm sure you can do this? :) Updated my answer to reflect this. (Have to leave you a little work!) –  James Mills yesterday
 
You're right I'm exploring csselect & spyda. Thanks for the heads up! –  user1656343 yesterday
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