Re: [Groff] parsing a corner specification

[Clarke Echols]

According to my eroff manual (from Elan Computer Group, Inc.)
the circle allowed-attribute list allows radius, diameter,
height, width, at, invis, same, and text.  "at" takes a position
argument.

You might try a 'move _to_;' then the circle specification...
The semicolon separates operations and they can be chained
together.  The 'at' attribute locates the center of the circle
at the position specified.

Pic isn't something I've used much at all, so I'm definitely
no guru here.

Clarke

Joel E. Denny wrote:
> I am trying to understand GNU pic's parser as it relates to an extension I 
> am working on for Bison.  However, I've never used pic before, so some of 
> my questions may be naive.
>
> I checked out Groff from CVS and built it.  The most recent ChangeLog 
> entry at the time was 2007-07-15.
>
> I then ran:
>
>   % cat > test.pic
>   .PS
>   A: circle "A"
>   B: A left
>   circle "B" at B
>   .PE
>   % src/preproc/pic/pic test.pic > test.groff
>   src/preproc/pic/pic:test.pic:4: syntax error before `left'
>   src/preproc/pic/pic:test.pic:4: giving up on this picture
>
> However:
>
>   % cat > test.pic
>   .PS
>   A: circle "A"
>   B: A upper left
>   circle "B" at B
>   .PE
>   % src/preproc/pic/pic test.pic > test.groff
>
> There is no error, and the circle labeled B is positioned at the upper 
> left corner of the circle labeled A.
>
> The only difference in the input is the word "upper".  Is this apparent 
> discrepancy in behavior intended?  If not, should both or neither of these 
> inputs be a syntax error?
>
> I've searched the web and Open Group for some roff or pic standards 
> document.  So far, I haven't found one.  Does one exist?  `man roff' says 
> Groff is the de facto standard.  Is that still the closest we have to a 
> formal standard?
>
> Thanks.