R devel - Nov 2011 - Question on parsing R code from C

Hi all,

I am facing the necessity to parse R code from C-side. As a first approximation 
the goal would be a re-implementation of the R shell (not Rgui).

I read the document at http://cran.r-project.org/doc/manuals/R-exts.html section
5.12, and the related source code example. 

I have some questions:

1. I need to declare the types and function signatures that I am going to use 
for this task without having to actually include the R headers. Can I safely 
declare SEXP according to the following ?
typedef struct SEXP *unknwn_handle;
More in general, is there a reference document for the C API (listing function 
signatures, and type definitions) ?

2. If the parsed R code of the working implementation contain commands like 
plot(), will the opportune windows pop-up as if I were using the R shell (on 
both windows and unix systems) ?

3. What initialization do I need to perform to be in exactly the same starting 
state as if I had executed the R shell with the --vanilla option?


Any help or feedback is appreciated.

Thank you.

Kind regard

On Nov 8, 2011, at 2:42 PM, KR wrote:
> Hi all,
> 
> I am facing the necessity to parse R code from C-side. As a first
approximation
> the goal would be a re-implementation of the R shell (not Rgui).
> 
> I read the document at http://cran.r-project.org/doc/manuals/R-exts.html
section
> 5.12, and the related source code example. 
> 
> I have some questions:
> 
> 1. I need to declare the types and function signatures that I am going to
use
> for this task without having to actually include the R headers. Can I
safely
> declare SEXP according to the following ?
> typedef struct SEXP *unknwn_handle;
I'm not sure I understand this really - it doesn't define SEXP. I would
expect something like

typedef void *SEXP;

Which may work for declarations. Note, however, that for the actual code
you'll need to include the headers anyway.

> More in general, is there a reference document for the C API (listing
function
> signatures, and type definitions) ?
> 
http://r.research.att.com/man/R-exts.html is the documentation and the headers
(Rinternals.h mainly) is the canonical reference.

> 2. If the parsed R code of the working implementation contain commands like
> plot(), will the opportune windows pop-up as if I were using the R shell
(on
> both windows and unix systems) ?
> 
It depends on your settings - plot() uses whatever graphics device you tell it
to use, so plot() doesn't decide about that. If you use the proper
interactive graphics device *and* make sure you're serving the REPL then it
may work. Beware of interactions with your other parts, though, since you are
responsible for ensuring that it works.

> 3. What initialization do I need to perform to be in exactly the same
starting
> state as if I had executed the R shell with the --vanilla option?
> 
It depends on the OS and the way you are initializing R. In the simple case pass
the "--vanilla" as the argument when initializing R. Please read the
section about embedding, it has examples. Also see the other R GUIs to
understand the complexities involved.

BTW: you subject has absolutely nothing to do with your question - your'e
asking about embedding R ;)

Cheers,
Simon


> 
> Any help or feedback is appreciated.
> 
> Thank you.
> 
> Kind regard
> 
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