R_parseVector and syntax error [was: error messages while parsing with rniParse]
Simon Urbanek wrote:
On Jun 18, 2009, at 17:02 , Duncan Murdoch wrote:
Romain Francois wrote:
Hello,
[I'm redirecting this here from stats-rosuda-devel]
When parsing R code through R_parseVector and the code generates an
error (syntax error), is there a way to grab the error.
It looks like yyerror populates the buffer "R_ParseErrorMsg", but
then the variable is not part of the public api.
Would it be possible to add yet another entry point to the parser
that would basically wrap R_parseVector so that it would have an
extra char* argument that would bring back the error message if
there is an error?
I would oppose that. Suggest ways to reduce the complexity of the
parser interface and I'd be interested. It's a nightmare to make
any changes there.
You can always call the R function wrapped in try(), so it's not as
though this would give you anything that you don't already have
access to.
I'm not quite following - we're talking about R_ParseVector in C code so the point is that the C code gets access to the error message so it can relay it to the user.
I understood that. But the C code can get the error message by evaluating an R expression and looking at the result.
There are no R-level functions involved here. The issue here for the moment is that this information is retrievable at R level but not (officially) at the C level.
I wouldn't mind exposing the underlying information in a clean way, but the string in R_ParseVector isn't all a front end should get. At the time of an R_ParseVector syntax error, the parser knows what token it couldn't handle, and it knows its classification, and the location in the file where it came from. Not all of that makes it through to the error message.
As for reducing complexity - technically, there is no complexity added since all this is already in place ... [adding extra char * argument to ParseVector may not be the best way but that's not what I'm arguing for].
It was what I was arguing against. Duncan Murdoch
Or am I missing something?
Cheers, S
Romain
Simon Urbanek wrote:
On Jun 15, 2009, at 12:05 , Romain Francois wrote:
Hello,
In JRI, is there a way to get the error message that is generated
by the
parser through rniParse
For example, if I have this :
long y = re.rniParse( "rnorm( 10 ))", 1 ) ;
this obviously generates a parse error, so y will be the same as
(R_NilValue) :
long null_id = re.rniEval( re.rniParse( "NULL", 1 ), 0 ) ;
I guess the underlying question is : "Is R_ParseErrorMsg exposed to
JRI".
AFAICT R_ParseErrorMsg and friends are not exposed by the R API -
they are not accessible outside, so they cannot be use by JRI. It
would be nice if there was a way of accessing that info, but R
doesn't currently support that.
Cheers,
Simon
The reason is I would like to bring back the message as part of an
exception generated when the code does not parse.
Romain
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