Re: [GNU-COBOL] GNU-COBOL list reborn

[Michael McKernan <mck@tivoli.mv.com>]

Tim Josling wrote:
> What would happen if the "2" was instead a function call (which
> counts as an "identifier"), like
> 
> move a to b(function exponential(2):3).
> 
> or a complex identifier, like
> 
> move a to b(z of x of y of t of u of w:3).
> 
Thanks for keeping me honest, Tim.  I should have checked the standard, but
I must have been thinking about the restricted level 1 version.  Sorry.

> What I am getting at here is that the colon is not necessarily
> any particular finite number of tokens ahead. Without knowing
> anything about the parser generator, it concerns me that many
> parser have finite lookahead
>
The rules should have looked like this

	identifier : ident (qualifier)*
			   ( (OPAREN arith_exp COLON)? refmod
			   |	( (OPAREN)? subscripts { refmod }
				|
				)
			   )
		   ;

	refmod	: OPAREN arith_expr COLON { arith_expr } CPAREN
		;

Pccts is the exception, Tim. It _does_ have infinite look-ahead. That sounds
expensive, but it's only used when it's required so as a practical matter,
it isn't a problem.  In the "built by hand" parser that I last used, we did
have a rule that would accept either subscript or refmod, but I think that
must have left some cleaning up to do in the semantics pass. I have no idea
how other parsers handle it.
  



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