Replace all urls in string not matching url pattern in php

Question

I'm using the following code to filter out urls from a block of HTML text in PHP.

preg_replace('#<a(?![^>]+?href="?http://keepthisdomain.com/foo/bar"?).*?>(.*?)</a>#i', '\1', $text);

It's intended to replace all url's that do not match the specified url pattern. However I do want to include all tags that have the attribute rel="shadowbox[a]" set.

How can I modify this preg_replace to do that?

To clarify, which is a match: (1) a tags with the specified URL pattern and the rel="shadowbox[a]" attribute, or (2) a tags with the specified URL pattern or the rel="shadowbox[a]" attribute? — elixenide
– elixenide, Commented Mar 5, 2014 at 21:33
P.S. You are better off not using regex at all and using a parser instead, for the reasons set forth in this answer. — elixenide
– elixenide, Commented Mar 5, 2014 at 21:35
It's a tag with the rel="shadowbox[a]" attribute. I want to keep those urls (along with all hyperlinks that link to keepthisdomain.com/foo/bar) — lordmj
– lordmj, Commented Mar 5, 2014 at 21:42

Community · Accepted Answer · 2017-05-23 11:57:49Z

0

You are better off not using regex at all and using a parser instead, for the reasons set forth in this answer.

That said, you can do it with regex, but it's tricky:

preg_replace('#<a(?![^>]+?\bhref="?http://keepthisdomain\.com/foo/bar"?|[^>]+\brel="shadowbox\[a\]").*?>(.*?)</a>#i', '\1', $text);

Details on the regex:

<a(?![^>]+?\bhref="?http://keepthisdomain\.com/foo/bar"?|[^>]+\brel="shadowbox\[a\]").*?>(.*?)</a>

Regular expression visualization

Out of the following four tags, only the third would be replaced:

<a href="http://keepthisdomain.com/foo/bar">foo</a> // left alone
<a href="http://keepthisdomain.com/foo/bar" rel="shadowbox[a]">foo</a> // left alone
<a href="http://rejectthis.com/foo/bar">foo</a> // REPLACED
<a href="http://rejectthis.com/foo/bar" rel="shadowbox[a]">foo</a> // left alone

Edited with a minor tweak to make it match a literal . in .com, using \.

edited May 23, 2017 at 11:57

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answered Mar 5, 2014 at 21:45

elixenide

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