regexp quick fix, identifying elements in html

chr15t0 · 06-04-2006, 04:48 AM

guys -

I know there are modules on cpan which will help with this, but I just want to know if it can be done with a pure regex.. a guy at worked asked me this yesterday - he just wanted a quick oneliner. I tried and got stuck and now it's really niggling me.. anyway, what do you reckon:

A page of html contains sections like this:

<span>bla foo bla bla foo moo</span><div> bla foo bla bla foo</div>

The challenge is to write a regexp which will replace all occurences of 'foo' with 'bar', but only if between div tags - ie the ones in the span won't be affected.

Does anyone think that's possible in a single expression?

christo

jim mcnamara · 06-04-2006, 11:40 AM

http://www.regular-expressions.info/refadv.html

check the lookaround (lookbehind) section
or
the section on \G

These allow you to specify that your foo occurs after a </splat>
You can also use sed, it has syntax to look for a second foo on a line

Code:

's/foo/bar/2'  replace #2 foo
sed 's/\(.*\)foo/\1bar/'   replace last foo

chr15t0 · 06-06-2006, 03:35 AM

if anybody's wondering, I fixed it with the following expression:

1 while s/&(?=[\w&]+<\/link>)/&/g;

if you want to see it in action, just run the following script:

Code:

#!/usr/bin/perl

$_="<title>foo&bar</title><link>but&thisand&this</link><link>foo&barfsfoo&badrffoo&basrfoo&bar</link><link>booo&thisand&this</link>";

print "$_\n";
1 while s/&(?=[\w&]+<\/link>)/&amp;/g;
print "$_\n";

christo