Need variable width negative lookbehind replacement

Posted by Technoh on Stack Overflow See other posts from Stack Overflow or by Technoh
Published on 2010-04-27T21:43:40Z Indexed on 2010/04/27 21:53 UTC
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regex

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php

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negative-lookbehind

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lookbehind

I have looked at many questions here (and many more websites) and some provided hints but none gave me a definitive answer. I know regular expressions but I am far from being a guru. This particular question deals with regex in PHP.

I need to locate words in a text that are not surrounded by a hyperlink of a given class. For example, I might have

This <a href="blabblah" class="no_check">elephant</a> is green and this elephant is blue while this <a href="blahblah">elephant</a> is red.

I would need to match against the second and third elephants but not the first (identified by test class "no_check"). Note that there could more attributes than just href and class within hyperlinks. I came up with

((?<!<a .*class="no_check".*>)\belephant\b)

which works beautifully in regex test software but not in PHP.

Any help is greatly appreciated. If you cannot provide a regular expression but can find some sort of PHP code logic that would circumvent the need for it, I would be equally grateful.

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