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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