I'm getting content from database:

`$data="some markup <pre> <code> some code </code> </pre> some markup"`

What I want to do is following

If $data has `<pre> <code> </code> </pre>` inside, then do something and pass `some code` through htmlspecialchars() function. Then merge as it was before. Something like:

`$data="some markup <pre> <code> htmlspecialchars(some code) </code> </pre> some markup"`

Can't figure out how to do it..