Re: Match at least one?

[Evan Lavelle]

If there are only 3 mandatory blocks then, in principle, you can look 
for all possible combinations in the input:

message
  : M1 M2 M3
  | M1 M3 M2
  | M2 M1 M3
  | M2 M3 M1
  | M3 M1 M2
  | M3 M2 M1
  ;

However, you've got a problem in that you need 'at least one' of the 
mandatory blocks, and the repeats can presumably come in any order. 
Explicitly listing all expected variants can be useful in simple cases, 
but not in this case.

So, you're right, you need to do some post-processing. This is easy - 
just push the type of the block you've just parsed onto a list whenever 
you see a block, and then process the list when you've seen your 
terminator. This is the "right" way to do it - keep the parser for 
parsing, and do any semantic analysis afterwards.

-Evan