constraining chars for all cols of a table

Hi:

I have to constrain the chars used for table columns. For example...
create table foo (col1 text, col2 text, col3 text);
... where
col1 has to be all uppercase, nothing but [A-Z]
col2 has to be all lowercase [a-z] plus [0-9] is also allowed
col3 can be mixed case plus [0-9] and sqr brackets (but nothing else).

I could put a check constraint on each/every table column, but that seems complicated and potentially slow.

I could do this check using the existing insert and update before triggers, but then I'd have to loop through all the columns and decide one by one how to
check them. Again, slow and complicated.

Is there a better way? Whatever I do, I'd have to be able to capture violations to provide informative feedback to the users through the perl script that'll actually be doing the insert/update.

Thanks in Advance !