Regex to replace html links to plain-text URLs

Question

I need to replace links in html:

<a href="http://example.com"&gt;&lt;/a&gt;

To just plain-text url address:

http://example.com

UPD. Some clarification here, i need this to strip down html tags from text but preserve link locations. It's purely for internal use, so there won't be any crazy edge-case code. Language is python in this case, but i don't see how's that relevant.

Answer 1

>>> s="""blah <a href="http://example.com"&gt;&lt;/a&gt; blah <a href="http://www.google.com"&gt;test&lt;/a&gt;"""
>>> import re
>>> pat=re.compile("<a\s+href=\"(.*?)\">.*?</a>",re.M|re.DOTALL|re.I)
>>> pat.findall(s)
['http://example.com', 'http://www.google.com']
>>> pat.sub("\\1",s)
'blah http://example.com blah http://www.google.com'

for more complex operations, use BeautifulSoup

Answer 2

Instead of using regex, you could try to use unlink with minidom

Answer 3

As I said before if you are ok with some mistakes and/or have some amount of control over the input, you can make some compromises in completeness and use Regex. Since your update says this is the case, here's a regex that should work for you:

/<a\s(?:.(?!=href))*?href="([^"]*)"[^>]*?>(.*?)</a>/gi

• $1: The HREF
• $2: Everything inside the tag.

This will handle all the test cases below except the last three lines:

Hello this is some text <a href="/test">This is a link</a> and this is some more text.
<a href="/test">Just a link on this line.</a>
There are <a href="/test">two links </a> on <a href="http://www.google.com"&gt;this line</a>!
Now we need to test some <a href="http://www.google.com" class="test">other attributes.</a>. They can be <a class="test" href="http://www.google.com"&gt;before&lt;/a&gt; or after.
Or they can be <a rel="nofollow" href="http://www.google.com" class="myclass">both</a>
Also we need to deal with <a href="/test" class="myclass" style=""><span class="something">Nested tags and empty attributes</span></a>.
Make sure that we don't do anything with <a name="marker">anchors with no href</a>
Make sure we skip other <address href="/test">tags that start with a even if they are closed with an a</a>
Lastly try some other <a href="#">types</a> of <a href="">href</a> attributes.

Also we need to skip <a malformed tags.  </a>.  But <a href="#">this</a> is where regex fails us.
We will also fail if the user has used <a href='javascript:alert("the reason"))'>single quotes for some reason</a>
Other invalid HTML such as <a href="/link1" href="/link2">links with two hrefs</a> will have problems for obvious reasons.