Re: gnubol: Re: Magic tokens

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

>>>>> "Bob" == RKRayhawk  <RKRayhawk@aol.com>
>>>>> wrote the following on Mon, 6 Dec 1999 16:10:55 EST

  Bob> Let me quote some material that went back and forth enough I
  Bob> don't know who said what, but it is important. Then if you
  Bob> will consider my comment below.


  Bob> In a message dated 12/4/99 9:41:38 PM EST, mck@tivoli.mv.com
  Bob> writes:

  Bob> << >>>> "Mike" == Michael McKernan <mck@tivoli.mv.com>
  >>>>>> wrote the following on Sat, 04 Dec 1999 21:23:50 -0500
 
  Mike> Tim, I don't know if this translates to bison very well, but
  Mike> I am thinking along these lines.
 
  Bob>  add_imperative
  Bob>     : add_common { size_err end_add | end_add }
  Bob>     ;
  Bob>  add_stmt
  Bob>     : add_common { size_err } { end_add }
  Bob>     ;
  Bob>  add_common
  Bob>     : ADD
  Bob>       ( CORR identifier TO identifier { ROUNDED }
  Bob>       | ( identifier | NUMERIC_LITERAL )+
  Bob>          ( giving_phrase
  Bob>          ! TO ( identifier | NUMERIC_LITERAL ) giving_phrase
  Bob>          | TO ( identifier { ROUNDED } )+
  Bob>          )
  Bob>       )
  Bob>     ;
 
  Mike> A greedy parser will grab the size error for the appropriate
  Mike> verb.  (You'll remember that {} means optional.)
 
  Bob>  Well, now that I look at it, it may be a reduce/reduce
  Bob> conflict since both rules are capable of deriving the same
  Bob> string.  Well, FWIW.
 
 
  >>>


  Bob> At any given time we need competition between
  Bob> A)
  Bob>   simple unterminated arithmetic statement
  Bob>   simple explicitly terminated arithmetic statement
  Bob>   sticky arithmetic with a conditional unterminated (A.3)
  Bob>   arithmetic with a conditional terminated (thus no longer
  Bob>   sticky) (A.4)
  Bob> B)
  Bob>   sticky arithmetic with both conditional branches yet
  Bob>   unterminated arithmetic with both conditional branches 
  Bob>   terminated (thus nolonger sticky)

  Bob> (B.2)

Honest Bob, there is no problem.  Once we buy into the nearest
preceding eligible verb binding rule, we can only hold on and go
where it takes us.  There are no choices, no alternatives.  The
grammar above is entirely adequate (along with the rules referenced
but not shown); nothing more is needed.

Best regards,

Mike



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