| Subject: | RD_AUTOSTUB does not work with precompiled parsers |
So, this works to set RD_TRACE:
perl -MParse::RecDescent -s - -RD_TRACE grammar NewMakepp::Grammar
Unfortunately, it looks like the path taken by the precompilation fails
to actually check for undefined rules. This may be a bug, or may have
been intentional, I'll have to follow up with Damian.
Even if this were fixed, I'm not sure how useful the '-s' command line
option is, as -RD_AUTOSTUB will set $::RD_AUTOSTUB to '1'. An
undocumented feature of $::RD_AUTOSTUB is that if it has a boolean-true
value, an undefined rule named 'foo' will not get the production
foo: 'foo'
but instead get the production:
foo: $::RD_AUTOSTUB
Which, for -s -RD_AUTOSTUB, will generate:
foo: '1'
1: '1'
Which probably isn't what you wanted in the first place.
Long story short, RD_AUTOSTUB doesn't currently work with precompilation
of parsers. You'll have to either not precompile, or define your own
stub productions.
Note that this isn't unique to the command line, but appears to be a
problem with the Precompile method. The callstack is something like:
script: Parse::RecDescent->Precompile($grammar, $class, $sourcefile)
Precompile: $self = Parse::RecDescent->new($grammar,1,$class)
new: $self->Replace($grammar, 1, $class)
Replace: _generate($self, $grammar, 1(fromsplice), 1, $class);
_generate: my ($self, $grammar, $replace, $isimplicit, $isleftop) =
(@_, 0);
So, the '1' added to @_ from Precompile in the call to new() ends up
becoming $isimplicit.
$isimplicit prevents $self->_check_grammar() from being called, which is
the function that does the RD_AUTOSTUB checking/generation. I'll have
to look into why _check_grammar is skipped for $isimplicit cases.
There also appears to be another bug here, where the $class parameter
gets incorrectly propagated from Precompile into $isleftop inside of
_generate, which is probably not correct. Unless I've misread the code
somewhere.