R help - Aug 2007 - Any parser generator / code assistance for R?

Hi,

Is there any parser generator like www.antlr.org?  Moreover, how does simple 
code assistance work currently in R? By 'simple code assistance' I meant
things like:

Object$M<TAB> --> Object$Method

>>>>> "A-" == Ali - <saveez at hotmail.com>
>>>>>     on Sat, 18 Aug 2007 00:40:52 +0100 writes:
    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  ;-)

Regards,
Martin

> 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. 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? 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.
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On 8/17/07, Ali - <saveez at hotmail.com> wrote:
> Hi,
>
> Is there any parser generator like www.antlr.org?  Moreover, how does
simple
Given the response, it looks like no one has come up with an antlr
parser for R but there are some facilities within R itself.

showTree() in the R codetools package which can generate a
Lisp style expression for any R expression:
> library(codetools)
> showTree(quote(for(i in myvec[1:3]) print(i+88*2+3*4)))
(for i ([ myvec (: 1 3)) (print (+ (+ i (* 88 2)) (* 3 4))))

Looking at the source of showTree would show you how to walk
an R parse tree.

The Ryacas R package has a recursive descent R parser that is used to
process R code translating it to yacas and it also can translate OpenMath
XML code generated by yacas to R.  See:
http://ryacas.googlecode.com