Things do look problematic here.
Could you create a small example duplicating the failure? An advantage
of these is that it clarifies for me exactly what you expect to happen.
A complication here is that in addition to Perl undef's, I introduced
"whatever" variables to Marpa. These are allowed to have any value --
presumably they'd be for cases where you ignore the value. That is, an
'undefined' value must be undef, but a 'whatever' value can be undef one
time, 42 the next, and "hello" the next.
"Whatever" values were intended to save stack operations. Marpa's NAIF
did these via callback, so every stack op save was a big win. When a
whatever value needs to be put on the stack, it's a no-op, whereas when
an Perl undef needs to be put on the stack, it's a callback -- a vast
difference in resource.
With the SLIF, I implement callbacks more cheaply, and future changes
may reduce this cost further. This means the time and trouble to track
whatever values is probably not worth it. "Whatever" values may be
deprecated in Libmarpa. I think I kept them out of the Marpa::R2
documentation, so this deprecation would only be relevant at the
Libmarpa and THIF levels.
-- jeffrey
On 01/07/2014 02:12 AM, Ruslan Zakirov wrote:
Hi,
I know that at some point ignorable products was optimized and
resulted in undefined (=== random) values in actions, but hell let me
do what I mean.
Doc says pass reference to value and I'm passing it reference to undef.
It worked just fine at some point but then it was broken.
Responsible change is
dae6a5697dec6a5bb039418e3329db615e535dec and the following part in
particular:
- push @{$token_values}, ${$value_ref};
+my $value = ${$value_ref};
+last SET_VALUE_IX if not defined $value;
+ push @{$token_values}, $value;
I don't see how it is related to whole change.
Also, I see that "# Position 1 is reserved for undef" in $token_values
then this probably just a bug and the following should be applied:
diff --git a/cpan/lib/Marpa/R2/Recognizer.pm
b/cpan/lib/Marpa/R2/Recognizer.pm
index d700590..219e839 100644
--- a/cpan/lib/Marpa/R2/Recognizer.pm
+++ b/cpan/lib/Marpa/R2/Recognizer.pm
@@ -669,10 +669,9 @@ sub Marpa::R2::Recognizer::alternative {
{
Marpa::R2::exception('alternative(): value must be undef
or ref');
} ## end if ( $ref_type ne 'SCALAR' and $ref_type ne 'REF'
and...)
+ last SET_VALUE_IX if not defined $$value_ref;
$value_ix = scalar @{$token_values};
- my $value = ${$value_ref};
- last SET_VALUE_IX if not defined $value;
- push @{$token_values}, $value;
+ push @{$token_values}, $$value_ref;
} ## end SET_VALUE_IX:
$length //= 1;
--
Best regards, Ruslan.
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