When I came up with the Microformat parser, I decided the best way to parse the HTML for microcontent is by using CSS selectors. They’re simple to write, easy to understand and already familiar to anyone working with (X)HTML. It turned out to be a good choice and a time saver.
PHP and later on with Ruby. (Somewhere on my computer, there’s also a JavaScript implementation)
Right now I’m looking at the new CSS3 working draft and trying to decide which new features to add. Matching attribute values that begin, end or contain a string looks simple. I also like the new combinators for Foo follows Bar (Bar ~ Foo) and Foo is not Bar (Foo:not(Bar)). There’s much more in the new selector specification, but these ones strike me as the most interesting.
It might also be time to see if I can extract the CSS selector code out of the parser for use in other places.
And expect more Microformat goodness to come soon. The move to WordPress 2.0 broke my existing plug-in, so it’s time to figure out how to use the WYSIWYG editor. I also have working, but unpolished code for doing cool stuff with events, and some ideas on listings. Just need the time to get the code in shape.