search string / query format

I'm going to create a search page that accepts input similar to places like Yahoo and Google. Example input would be: Keyword AND keyword2 Keyword -keyword2 +keyword3 "keyword keyword2" -keyword3 Rather than reinvent things though, I'm wondering if anyone here happens to have a script or function that will handle that type of input. It would be great if someone already has a function that accepts the initial query, a table to query against, and a list of fields to query against, and returns the appropirate SQL statement. Also, I've heard that MySQL's indexing can support some of this, but I'm not sure how much. Thanks in advance for any pointers or info you might have on this. -Ed