RE: PERFORM token (was RE: gnubol: Hacks needed to parse COBOL

["William M. Klein" <wmklein@ix.netcom.com>]

How about 6 levels deep in the '85 Standard - it was 3 in '74.

Bill Klein
  wmklein <at> ix.netcom.com

> -----Original Message-----
> From: owner-gnu-cobol@wallace.lusars.net
> [mailto:owner-gnu-cobol@wallace.lusars.net]On Behalf Of
> RKRayhawk@aol.com
> Sent: Friday, December 03, 1999 8:52 AM
> To: gnu-cobol@lusars.net
> Subject: Re: PERFORM token (was RE: gnubol: Hacks needed to parse COBOL
>
>
> In a message dated 12/3/99 8:19:26 AM EST, mck@tivoli.mv.com writes:
>
> ....
> <<
>  varying_phrase
>     : VARYING identifier
>       FROM (identifier | INTEGER)
>       BY (identifier | INTEGER)
>       UNTIL condition
>     ;
>   >>
> ...
> This is a side note not responsive to the main point of your post, the
> VARYING UNTIL clause can be optionally three levels deep
>
>     : VARYING id  FROM  id BY id UNTIL condition
>           AFTER id  FROM  id BY id UNTIL condition
>           AFTER id  FROM  id BY id UNTIL condition
>
> I expect you know that, but just to be as supportive as possible,
> I've noted
> it..
>
> It is interesting that the FROM token can occur also in arithmetic
> statements
> and so we may need precedence markers on VARYING FROM clauses and SUBTRACT
> statements just to get them fitted out correctly precedence wise. That
> comment applies to bison. But the precedence issue and
> shift/reduce behavior
> is just as relevant to PCCTS, is it not? How do you establish token
> precedence, and how to override in these kind of statements.
>
> And just to make sure that we don't run out of monkey wrenches to monkey
> around with, notice that AFTER can occur in WRITE and INSPECT statements,
> where our shift/reduce concerns will surely be distinct from those in the
> varying VARYING clause. And come to think about it AFTER can also
> appear in a
> completely different role in the PERFORM's TEST clauses. It thus weaves in
> and out of the PERFORM statement's shift / reduce domain. A very
> cool token
> if there ever was one. %prec can help here in bison, how are such
> precedence
> governed shift/reduce concerns addressed in PCCTS.
>
> Best Wishes
> Bob Rayhawk
> RKRayhawk@aol.com
>
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