Re: YACC rules to regex rules ?

[perlfan]

This may not help and is not what you asked for, but may lead you to a helpful path nonetheless. thread on converting YACC to ANTLR. The link of interest is 404'ing, but thankfully the Internet never forgets (most of the time). The link there provides a zip. So it's also Java I think, so sorry.

[LanX]

Thanks.

I think I can solve it by myself, the format in a2p.y (which I had to google on github) looks a lot like perlretut#Defining-named-patterns plus embedded Perl code.

I'm just asking here before I reinvent the wheel.

[LanX]

> perlretut#Defining-named-patterns plus embedded Perl code

Unfortunately it's not obvious how to implement precedence and associativity with named patterns.

This requires at least one lookahead for an operator.

Reimplementing the C code from Yacc and Lex would be quite slow.

I looked at CPAN for efficient recursive parsers allowing "precedence" but not much luck.

• Marpa::R2 requires an XS module
• Parse::RecDescent doesn't mention precedence
• Regexp::Grammars neither

I'm giving up here.

While I'm sure it's possible to translate YACC rules to efficient regular expressions, it would be quite time consuming.

Parser generators are not trivial.

Update

FWIW I found some good threads on the topic, but it'd be cool to transform YACC rules to efficient regexes, because we could easily adapt a parser to language changes.

NB: There are multiple versions of AWK available.

Some interesting threads

• Parsing with Regexes and Beyond
• Re: Use cases for 'sub Pckg::func { }' ?

[tybalt89]

There is or used to be a Parse::Yapp

[Anonymous Monk]

??

https://metacpan.org/source/BJOERN/Parse-ABNF-0.30/eg/abnf2xlx.pl

RFC: A walkthrough from JSON ABNF to Regexp::Grammars

Convert Augmented BNF (ABNF) to Regexp::Grammars

my($parser)=new Parse::Yapp(inputfile => $filename);
Work( $parser->{GRAMMAR} );