The goal of cbuild is to provide tools for working with C both interactively and when constructing an R package. The two broad goals are:
Provide a way to interactively source C code into your R session.
See source_function()
and source_code()
to get started.
Provide an automatic registration system for R package developers
that use C, see process_attributes()
. It can automatically
generate the init.c
file for you, using a comment system similar
to Rcpp::export
. For example, the following would generate an
entry for the C function fn()
in init.c
, and generate the glue
code to export it as an R routine named fn
, which you could call
from the R side with .Call(fn, 1)
:
// [[ export() ]]
SEXP fn(SEXP x) {
return x;
}
You can install the development version from GitHub with:
# install.packages("devtools")
devtools::install_github("DavisVaughan/cbuild")
library(cbuild)
The easiest way to get started is with source_function()
, which allows
you to source a C function from text. It automatically includes R.h
and Rinternals.h
for you to use.
fn <- source_function("
SEXP fn(SEXP x) {
return x;
}
")
fn(1)
#> [1] 1
From there, you can use source_code()
to source larger chunks of code.
Tag functions that you want to export with // [[ export() ]]
.
fns <- source_code("
static SEXP helper(SEXP x) {
return x;
}
// [[ export() ]]
SEXP fn1(SEXP x) {
return helper(x);
}
// [[ export() ]]
SEXP fn2(SEXP x, SEXP y) {
double result = REAL(x)[0] + REAL(y)[0];
return Rf_ScalarReal(result);
}
")
fns$fn1(1)
#> [1] 1
fns$fn2(1, 2)
#> [1] 3
If you have a full file to source, you can use source_file()
.
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