[Groff] Re: gpic bug

[Russ Cox]

This is the rules for position and everything it depends
on except expr, which are just arithmetic expressions.

Both 0,0 and (0,0) work for me in

        box with ___ at (0,0)

I also note that the AT&T pic grammar has 208 shift/reduce
conflicts, although with appropriate explicit precedence tags
I'm sure they could be removed.  But since the default resolution
is apparently what we want, it hasn't been a problem.

Russ

position:               /* absolute, not relative */
          place
        | '(' position ')'                      { $$ = $2; }
        | expr ',' expr                         { $$ = makepos($1, $3); }
        | position '+' expr ',' expr            { $$ = fixpos($1, $3, $5); }
        | position '-' expr ',' expr            { $$ = fixpos($1, -$3, -$5); }
        | position '+' '(' expr ',' expr ')'    { $$ = fixpos($1, $4, $6); }
        | position '-' '(' expr ',' expr ')'    { $$ = fixpos($1, -$4, -$6); }
        | position '+' place                    { $$ = addpos($1, $3); }
        | position '-' place                    { $$ = subpos($1, $3); }
        | '(' place ',' place ')'       { $$ = makepos(getcomp($2,DOTX), 
getcomp($4,DOTY)); }
        | expr LT position ',' position GT      { $$ = makebetween($1, $3, $5); 
}
        | expr BETWEEN position AND position    { $$ = makebetween($1, $3, $5); 
}
        ;

place:
          PLACENAME             { y = getvar($1); $$ = y.o; }
        | PLACENAME CORNER      { y = getvar($1); $$ = getpos(y.o, $2); }
        | CORNER PLACENAME      { y = getvar($2); $$ = getpos(y.o, $1); }
        | HERE                  { $$ = gethere(); }
        | last type             { $$ = getlast($1, $2); }
        | last type             { $$ = getlast($1, $2); }
        | last type CORNER      { $$ = getpos(getlast($1, $2), $3); }
        | CORNER last type      { $$ = getpos(getlast($2, $3), $1); }
        | NTH type              { $$ = getfirst($1, $2); }
        | NTH type CORNER       { $$ = getpos(getfirst($1, $2), $3); }
        | CORNER NTH type       { $$ = getpos(getfirst($2, $3), $1); }
        | blockname
        | blockname CORNER      { $$ = getpos($1, $2); }
        | CORNER blockname      { $$ = getpos($2, $1); }
        ;

blockname:
          last BLOCK '.' PLACENAME      { $$ = getblock(getlast($1,$2), $4); }
        | NTH BLOCK '.' PLACENAME       { $$ = getblock(getfirst($1,$2), $4); }
        | PLACENAME '.' PLACENAME       { y = getvar($1); $$ = getblock(y.o, 
$3); }
        ;

last:
          last LAST             { $$ = $1 + 1; }
        | NTH LAST              { $$ = $1; }
        | LAST                  { $$ = 1; }
        | LAST                  { $$ = 1; }
        ;

type:
          BOX
        | CIRCLE
        | ELLIPSE
        | ARC
        | LINE
        | ARROW
        | SPLINE
        | BLOCK
        ;