On 8/20/2007 1:27 PM, Ali - wrote: >> A-> Hi,> A-> Is there any parser generator like www.antlr.org? Moreover, how >> does simple > A-> code assistance work currently in R? By 'simple code >> assistance' I meant > A-> things like:> > A-> Object$M<TAB> --> >> Object$Method> > If you really meant a list with components> or an S4 object >> with slots,> such code completion works at least since R 2.5.1, because of> >> the recent 'rcompletion' extensions of Deepayan Sarkar,> and of course in >> ESS (Emacs Speaks Statistics),> and I think in several other >> GUI/Environments as well.> > But if you are thinking OOP as in Java or C++ >> (and I think you> *are* thinking along that way), then rather learn> that S >> (and hence R) do OOP in a function-centric rather than class-centric> way; >> something which seems to be quite hard to grasp for many> who have been >> brought up in Java-like schools....> If you are still interested in R, look >> out for documents with> "S4" (or "formal methods and classes") and "R" in >> the title ;-) > I am looking for an implemented parser generator of 'R', not only S4 classes > or OOP style. By 'R', I mean 'R', it's that simple. > > I am not a big fan of the inconsistency in R grammer for the price of freedom > in bringing new inventions such as S4.
What inconsistencies are you talking about? There are plenty of semantic inconsistencies, but I can't think of any at the parser level. In general the parser doesn't know anything about S3, S4, etc. I understand this is a controversial subject and that many claim that in this way more options are brought to R. However, this makes R to look like a 'confused' language to me which is undecided between function-centric and object-oriented. We have the OOP package, the methods package and now the S4 classes which are very different to S3 and my understanding is that the S3-based packages are not automatically upgradable to S4. What if in 7 years or so the authors decide to have a S5 class scheme which is very different to both S3 and S4? > > In this way, it seems to me that there is no 'standard' in R. You may choose > a flavour for R like R-S4 or R-S3 or R-this or R-that, and then develop your > package based on that flavour. However, it looks like R-this and R-that > flavours are actually different languages sharing some syntax. > Here is a good demonstration for this problem: can we have one 'universal' > parser for R? Or do we need an R-this-parser and R-that-parser for each > flavour? There's currently only one parser for R, generated from src/main/gram.y. It seems that Martin said yes to the second question. > > Moreover, my question is still somehow un-answered: Is there any existing > ANTLR-based parser for R? I understand that in omegahat.org project, people > used ANTLR for RSJava, but i am not sure if that had anything to do with an > R-parser. I doubt it. The parser for R is written in yacc/bison, and since nobody has pointed to one based on ANTLR, it probably doesn't exist. Duncan Murdoch ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
