Re: segfault in glib-mkenums

[Max Horn <max quendi de>]

At 18:35 Uhr -0400 15.09.2001, Owen Taylor wrote:
> Max Horn <max quendi de> writes:
>
> >  A work around for the crash in glib-mkenums, that I believe should
> >  work on other OSes, too, and will even speed up glib-mkenums a bit is
> >  to change the three occurences of
> >
> >       while (m@/\*([^*]|\*[^/*])*\**$ x) {
> > 	my $new;
> > 	defined ($new = <>) || die "Unmatched comment in $ARGV";
> > 	$_ .= $new;
> >       }
>
> Hmmm, this got "deimproved" from the original version in
> gtk+/gtk/makeenums.pl in GTK+-1.2:
>
> 	while (m@/\*
> 	       ([^*]|\*(?!/))*$
> 	       @x) {
> 	    my $new;
> 	    defined ($new = <$file>) || die "Unmatched comment";
> 	    $_ .= $new;
> 	}

Ah I already wondered why the "x" option was specified if no 
comments/formatting are added to the regexp :)


> I believe the difference in efficiency here is that Perl can be
> smarter with fixed length repeating expression of the form:
>
>  (a|b)*
>
> Than one with a variable length repeating expression of the
> form:
>
>  (a|bb)*

Yeah; and I suspect the heavy recursion that kills me is at least 
partly due to this.


[...]


>  >
> >       while (m@/\*([^*]|\*[^/*])*\**$ x) {
> > 	my $new;
> > 	defined ($new = <>) || die "Unmatched comment in $ARGV";
> > 	next unless ($new =~ m \*/$@);
> > 	$_ .= $new;
> >       }
> >
> >
> >  This will skip intermediate lines in multi-line comments. Unless there
> >  is a flaw with this that I overlooked, it would be cool if it could be
> >  added to glib-mkenums in CVS! Thanks.
>
> This doesn't quite work, because we actually need the complete
> comment to handle multi-line pseudocomments.
>
> typedef enum {
>   foo_blah_abcd, /<*
>                      nick=blah_abcd
>                    *>/
>   foo_blah_efgh
> } Foo;


AAAhh! OK, I was not aware of these pseudo comments, I only took a 
quick look at the code. That of course explains the current code.


> You could write something like:
>
>       while (m@/\*([^*]|\*[^/*])*\**$ x) {
>  	my $new;
>  	defined ($new = <>) || die "Unmatched comment in $ARGV";
>  	next unless ($new =~ m \*/$@);
>  	$_ .= $new;
>       }
>
> if ([$_ ends in an open comment]) {
>     while (1) {
>         my $new;
>         defined ($new = <$file>) || die "Unmatched comment in $ARGV";
>         $_ .= $new;
>         break if ([$new closes comment] && ![$new ends in an open comment]);
>     }
> }
>
> But the simpler n^2 algorithm with the makeenums.pl regex's should
> work fine for comments up to a few hundred lines anyways.

Sadly, not at all for me :/. I know I know it is not your fault :) It 
is Perl who uses excessivly recursion.

Getting Perl to compile is not that easy, I will have to reformat one 
partition to UFS file system, since Perl won't build on a HFS+ 
filesystem, which apple machines usually use ... <sigh>

Anyway, for now I can workaround this problem, there are more 
pressing issues I need to look into :)


Thanks fo ryour help,

Max
--
-----------------------------------------------
Max Horn
Software Developer

email: <mailto:max quendi de>
phone: (+49) 6151-494890