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Re: union and stuff
From: |
Leah |
Subject: |
Re: union and stuff |
Date: |
Fri, 10 Oct 2003 08:40:09 -0600 |
On 09 Oct 2003 22:54:22 -0700
Paul Eggert <address@hidden> wrote:
> Leah <address@hidden> writes:
>
> > Is there a better way than placing...
> >
> > #define union struct
> >
> > ...in the user declarations, to allow more than one type of value to
> > be stored in a semantic value?
>
> Sure: leave the union alone, but have one of its members be the
> structure.
As an example:
%union
{
int num;
char *str;
}
%token NUM
%token STR
%type <num> NUM num
%type <str> STR str
%%
num: NUM
| str { $$ = $<num>1; }
;
str: STR { $<num>$ = atoi($1); $$ = $1; }
;
%%
Slightly contrived, maybe, but it shows the idea. It's more convenient
to refer to 'str' as $$ and $<num>$ than it is to refer to it as $$.str
and $$.num, but with YYSTYPE being a union it isn't possible for a
semantic value to simultaneously be a <num> and a <str>.
> > Is the help-bison list not working anymore?
>
> Sorry, I don't read it. What problem are you having with it?
It seems not to be receiving messages. Also the archives don't list
September or October.
--
Leah