How to write a own parser for full text search

Hi all,
I have installed PostgreSQL server on a Windows Server 2008 server and I
need to write a more complex parser than the default one in PostgreSQL.
Searching on internet i found this example:
http://www.sai.msu.su/~megera/postgres/gist/tsearch/V2/docs/HOWTO-parser-tsearch2.html
where the parser is written in C language. I would know if can I write
the parser in another language (Java, I'm very poor in C)? And, if I
can, what kind of file would contain the functions of the parser (a dll
file, a class file).
The last question is: in that example are used some functions
(PG_GETARG_POINTER, PG_GETARG_INT32, and so on) that seem PostgreSQL
specific functions; which functions can I use in java?
May be these are banal questions, but I'm a newbee and I don't found
more resources on Internet! :)

Thanks in advance,
Antonio.