Qualification (was RE: gnubol: Re: ref touch points

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

Speaking of the qualification rules,
 I just wanted to make certain that "you all" had come across the rule that
says that it *IS* legal to have data-items (or procedure-names) that are NOT
unique - and cannot be made unique - as long as they are never referenced in
any procedure division statement.  Eg.  The following is a valid program:

  Identification Division.
    Program-ID. Whatever.
  Data Division.
   Working-Storage Section.
  01 XYZ.
     05  ABC  Pic X.
  01 XYZ.
     05  ABC  Pic 9.
  Procedure Division.
  aSection.
   aParagraph.
        Display "here"
          .
  aSection.
   aParagraph.
        Display "there"
         .
   aParagraph.
        Stop Run
            .


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 Michael McKernan
> Sent: Saturday, December 04, 1999 11:58 AM
> To: gnu-cobol@lusars.net
> Cc: mck@tivoli.mv.com; mck@tivoli.mv.com
> Subject: Re: gnubol: Re: ref touch points
>
>
> >>>>> "Mike" == Michael McKernan <mck@tivoli.mv.com>
> >>>>> wrote the following on Sat, 04 Dec 1999 12:22:23 -0500
>
>   Mike> No, I have not made myself clear.  This is not a parsing
>   Mike> issue.  Let's say we have the following records.
>
>       01 A.			01 B.
>          02 B.			   02 B.
> 	    03 C.		      03 C.
> 	       04 D.		         04 D.
> 	          05 X.			    05 Y.
> 		     06 Z PIC 9.	       06 Z PIC X.
>
>   Mike> The programmer may legitimately reference Z of Y and it is a
>   Mike> unique reference.  Since the name at the top of the tree need
>   Mike> not be among the qualifiers, it becomes very inefficient to
>   Mike> do the lookup top-down.  What we do instead, is form chains
>   Mike> while we're building the symbol table of all the symbol table
>   Mike> entries that have the same name, then use those chains to
>   Mike> accomplish the lookup bottom-up.  We are now searching only
>   Mike> the trees that contain the data-name instead of searching
>   Mike> every tree in the program.
>
> I should also have noted that when you start at an internal node and
> search upward, you are searching only a single unique path to the top
> of the tree.  In a top-down search, it is necessary to investigate
> every branch.
>
>
>
> --
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