Preparing full text search input for use in PostgreSQL 8.3

Hi,

It's nice that we have plainto_tsquery in addition to to_tsquery
because it's syntax is closer to what end users are used to (more like
Google search syntax with it's implicit "AND"). plainto_tsquery
however "cannot recognize either Boolean operators or weight
labels" (see: http://www.postgresql.org/docs/8.3/interactive/textsearch-controls.html#TEXTSEARCH-PARSING-QUERIES).
I wonder if anyone knows an open source project that created a piece
of code that parses any user input and converts it into proper query
syntax for to_tsquery (or returns an error message if no proper query
can be contructed).

Thanks!

Rudolph