SPI access to PostgreSQL query plan

Hi,

Is there a way to have access to PostgreSQL query plan and/or predicates inside a function using spi (or any other way)?
For example:

explain select * from my_func() as (code int, name varchar) where name like 'a%'; 
                          QUERY PLAN
--------------------------------------------------------------
 Function Scan on my_func  (cost=0.00..15.00 rows=5 width=36)
   Filter: ((name)::text ~~ 'a%'::text) 

I would like to know, inside the my_func function that PostgreSQL will filter the function's returned result on the name column 
with a like operator matching 'a%'. Since inside the my_func function I do another database query, I could "pre-filter" this 
query and reduce the amount of records returned.

If the whole plan cannot be exposed to spi, can only the part involved on filtering/manipulating the records returned from
 the function call?

Is the query plan saved in memory at a place where a spi function can have access? 

Regards,

Cristiano Duarte.