Efficient Text Parsing and Replacement

[k_shehadeh]

I've developed a simple template system wherein I replace text found within a set of enclosing text blocks ('[BEGIN] [END]', for example) with dynamically generated HTML code. To do this, the algorithm uses a strpos and substr, etc to parse the file and output the new HTML. The problem is that this is entirely too slow for my purposes. So I was wondering if anyone had any ideas for how I could better use PHP to get the results I need. The problem is that there can be multiple [BEGIN][END] tags throughout the file and I have to be able to support any whitespace characters in the tags or the contained text (e.g. [BEGIN ] or [ BEGIN ]). It would be great if there was some magical regular expression that will help me with this (I don't know the first thing about regexp). Any thoughts?

[elToro]

There's a nice, simple, fast one that comes with the book Web Application Development with PHP by Tobias Ratschiller and Till Gerken. I'd paste some of the code here, but I'm not sure whether it's freely redistributable. The comments don't say.

Edit: Found it online here.