[R-pkg-devel] New package with C++ code causes R abort in RStudio, not in R console.

[Vladimir Dergachev]

Hi Luc,

On Tue, 12 Nov 2024, Luc De Wilde wrote:

> Dear Vladimir,
>
> thank you for your reply.
>
> The model syntax is not simple though and the parser needs to look at the meaning in SEM terms to accept or reject certain things.

What do you mean by "SEM terms" ? I have not seen a situation yet that a 
grammar could not be handled by bison, it does have mechanism to deal with 
exceptions to pure LR syntax.

>
> Moreover, this is only a first step and later other calculations need to 
> be done in C++, which is why I find it important to know exactly why the 
> code works in R console but not in RStudio, and of course what can be 
> done to make it work in RStudio also.

My thought was that perhaps some sort of memory issues occurs because of 
the hand-written parser.

For example, one possibility is that stack sizes in R and Rstudio could be 
different. So if you are parsing something recursively it might work in 
one and not another.

The parsers generated by flex and bison are designed to handle arbitrary 
length inputs.

best

Vladimir Dergachev

>
> Kind regards,
>
>
> Luc De Wilde
>
> ________________________________________
> Van: Vladimir Dergachev <volodya using mindspring.com>
> Verzonden: dinsdag 12 november 2024 18:15
> Aan: Luc De Wilde <Luc.DeWilde using UGent.be>
> CC: r-package-devel using r-project.org <r-package-devel using r-project.org>; Yves Rosseel <Yves.Rosseel using UGent.be>
> Onderwerp: Re: [R-pkg-devel] New package with C++ code causes R abort in RStudio, not in R console.
>
>
> Hi Luc,
>
>   The standard tools for writing parsers are "flex" and "bison" - they
> generate code automatically and so can save you a lot of effort. For
> language with simple syntax you can get away with just using "flex".
>
>   Here are some examples:
>
> Flex:
>
> https://westes.github.io/flex/manual/Simple-Examples.html#Simple-Examples
>
> Bison:
>
> https://www.gnu.org/software/bison/manual/bison.html#Infix-Calc
>
> best
>
> Vladimir Dergachev
>
> On Tue, 12 Nov 2024, Luc De Wilde wrote:
>
>> Dear R package developers,
>>
>> I'm helping with the development of the lavaan package (see https://lavaan.ugent.be/) and currently writing a C++ version of the parser of the model syntax in lavaan. The package with C++ code is in  https://github.com/lucdw/lavaanC.
>>
>> When testing with a bunch of models, there is one model that causes an abort of the R session in RStudio (on Windows), but in the R console or in a batch job it causes no errors. The model is the following :
>> model <- '
>>     F1 =~ "a b"*X1
>>     F2 =~ a * X1 + 3*X2 # dat is hier een beetje commentaar
>>     # efa block 2
>>     efa("efa2")*f3 +
>>     efa("efa2")*f4 =~ y1 + y2 + y3 + y1:y3
>>     f4 := 3.14159 * F2
>>     F1 ~ start(0.76)*F2 + a*F2
>>     a == (b + f3)^2
>>     b1 > exp(b2 + b3) '
>>
>> and the translation can be tested - after installing lavaanC - with
>>
>> lavaanC::lav_parse_model_string_c(model)
>>
>> As mentioned, this causes an abort of the R session when executed in RStudio on Windows (10 or 11), but passes without problem in the R console or a batch job.
>>
>> Because many users are using RStudio I 'd like to tackle this problem, but don't know how to pinpoint the cause of the problem. I hope some of you have an idea how to handle this problem ...
>>
>> All the best,
>>
>>
>> Luc De Wilde
>>
>> ______________________________________________
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>>
>