From: David Krmpotic <davidk@...>
Date: 2007-02-06T05:37:45+09:00
Subject: Regular expressions (extracting urls)

Hi!

I have to extract an url from the text and make it a link (a href...)..
The trick is that I have to be careful not to replace the url, that are
already a part of the link.

so:

link = "Go here: http://www.something.com!"
link.gsub!(/https?:\/\/[a-z0-9\.\-\_=&\+\/\?]+/i, '<a
href=\'\0\'>\0</a>')

link becomes:
link = "Go here: <a
href='http://www.something.com'>http://www.something.com</a>!"

Now...

When the link is this:
link = "Go here: <a
href='http://www.something.com'>http://www.something.com</a>!"

The regular expression must not replace it!

I know that for example if I want to exclude the links that start with
xhttp, I can write:
link.gsub!(/([^x]https?:\/\/[a-z0-9\.\-\_=&\+\/\?]+)/i, '<a
href=\'\1\'>\1</a>')

but how can I exclude links that start with href=" and href=' ?
The problem is that I don't know how to specify that HREF cannot
preceede the link (cannot write [^href], [^(href)] doesn't seem to work
either and it also screws \n ... )


Please help !

David

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