function to filter out tokens (sql syntax lexical)?

Hallo,

according to
http://www.postgresql.org/docs/8.4/interactive/sql-syntax-lexical.htm
A token can be a key word, an identifier, a quoted identifier, a literal
(or constant), or a special character symbol.

I suppose these different tokens are used by the internal parser?
So my questions is,
is there a function one could use to filter out the specific tokes?

Example:

Given the statement: INSERT INTO MY_TABLE VALUES (3, 'hi there');

We can do something like:

select filter_tokens($$INSERT INTO MY_TABLE VALUES (3, 'hi there');$$);

With output:

token | type
Insert keyword
into keyword
my_table identifier
values keyword
..
'hi there' literal

or in another way with similar functionality?

mvg,
Wim