From: gga <GGarramuno@...>
Date: 2007-02-08T02:45:06+09:00
Subject: Re: Regular expressions (extracting urls)

On 5 feb, 17:37, David Krmpotic <dav...@easy.com> wrote:
> 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=' ?

You can exclude full words if you write regexes such as:

/(?!href=['"])/

Be careful about greediness, thou.   If you are doing any web
scraping, you also should look into something like WWW::Mechanize,
instead of re-inventing the wheel.