[Mesa-dev] [GLSL] defined expressions

[Carl Worth]

On Mon, 06 Dec 2010 20:23:52 +0000, José Fonseca <jfonseca at vmware.com> wrote:
> I suppose it is possible for space to be significant on a conditional
> expression, e.g.,
> 
>   #if foo ()
> 
> vs 
> 
>   #if foo

There's no significant whitespace here. A function-like macro can be
invoked without or without intervening whitespace between the macro name
and the '(' character. (It's only when *defining* the macro that the
space is significant.)

Meanwhile, a single macro "foo" cannot exist as both a function-like and
an object-like macro at the same time.

> If there isn't an obvious cleaner solution, would you mind I commit my
> original patch:
...
>         +|      DEFINED SPACE IDENTIFIER {
>         +               int v = hash_table_find (parser->defines, $3) ? 1 : 0;
>         +               $$ = _token_create_ival (parser, INTEGER, v);
>         +       }
>          |      DEFINED '(' IDENTIFIER ')' {
>                         int v = hash_table_find (parser->defines, $3) ? 1 : 0;
>                         $$ = _token_create_ival (parser, INTEGER, v);

This is at least inadequate in that it doesn't also add the case for:

	DEFINED SPACE '(' IDENTIFIER ')'

But a much cleaner solution would be to simply change the
conditional_tokens production to not have "space_tokens = 1". Ken and I
discussed this over lunch today and he agreed to do that.

> It doesn't makes things any worse, and it would allow us to focus on
> other problems.

Yes, getting this fixed and moving on will be great. :-)

-Carl

-- 
carl.d.worth at intel.com
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