On Jun 7, 2006, at 8:08 AM, Klaas-Jan Stol wrote:
I had a look at this, but I'm not that good at Perl, and regular
expressions. However, I found where things go wrong, so someone who
really groks REs may fix it.
I'm no Abigail, :-) but I'll try to help.
THe problem is (well, at least I think it is) at about line 440 in
pmc2c.pl
sub parse_pmc {
my $code = shift;
my $signature_re = qr{
^
(?: #blank spaces and comments and spurious
semicolons
[;\n\s]*
(?:/\*.*?\*/)? # C-like comments
)*
You're asking for multiple instances of something that could be
empty. I don't know if this is problematic, but I suspect it might
cause unnecessary backtracking. I would write: (?: [;\n\s] | (?:/
\*.*?\*/) )*
(METHOD\s+)? #method flag
(\w+\**) #type <<<==========I'd say
this should be (\w+\s*\**) so it matches a word (the return type),
optional spaces, and then optial *'s to indicate a pointer
\s+
(\w+) #method name
In the case where there are no '*'s in the text, the pattern '\s*'
eats up all the whitespace so the following '\s+' doesn't match.
Although I don't understand why backtracking wouldn't kick in and
make things match up, albeit inefficiently.
Try writing: ( \w+ (?: \s* \*+ )? )
(Some word characters optionally followed by any whitespace and some
'*'.)
\s*
\( ([^\(]*) \) #parameters
}sx;
If the fix as I noted above is done, things don't compile anymore.
I'm sorry I can't provide a real fix, but at least it's easier to
fix now, hopefully.
The real solution would use regular expressions but not rely on them.
I've been reading Higher Order Perl, by Mark Jason Dominus. It has a
chapter on writing parsers which is applicable to this discussion,
and I cannot recommend it highly enough.
Higher Order Perl
http://hop.perl.plover.com/
Josh
kind regards,
klaas-jan
Leopold Toetsch (via RT) wrote:
# New Ticket Created by Leopold Toetsch # Please include the
string: [perl #39313]
# in the subject line of all future correspondence about this
issue. # <URL: https://rt.perl.org/rt3/Ticket/Display.html?id=39313 >
It's easy to add 'invalide' code to .pmc files. E.g. I had defined:
METHOD parent() {
return PMC_pmc_val(SELF) ? PMC_pmc_val(SELF) : PMCNULL;
}
Due to the absence of a return value, the PMC compiler just
ignores this 'method' without further notice.
This also is happening, if there's just a whitespace before the '*':
METHOD PMC *parent() {
return PMC_pmc_val(SELF) ? PMC_pmc_val(SELF) : PMCNULL;
}
This totally valid C type declaration is just ignored.
Fixes welcome,
leo
