Build C, C++ and Fortran sources next to the Zig code

Adds Config/rzig/mixed: true to DESCRIPTION. The generated configure then leaves OBJECTS unset, so that R compiles every C, C++ and Fortran source file of src/ with its own compilers and links them with the Zig library, and src/entry.c leaves R_init_<pkg> to the package. The package's R_init_<pkg> registers its own routines with rzig_register(), which adds the Zig routines to the .Call routines:

Usage

use_rzig_mixed(path)

Arguments

path

Path to the package root.

Value

The path of DESCRIPTION, invisibly.

Details

#include <R_ext/Rdynload.h>

void rzig_register(DllInfo *dll, const R_CMethodDef *c_methods,
                   const R_CallMethodDef *call_methods,
                   const R_FortranMethodDef *fortran_methods,
                   const R_ExternalMethodDef *external_methods);

static const R_CallMethodDef call_methods[] = {
    {"legacy_add", (DL_FUNC) &legacy_add, 2},
    {NULL, NULL, 0}
};

void R_init_mypkg(DllInfo *dll) {
    rzig_register(dll, NULL, call_methods, NULL, NULL);
}

Dynamic symbol lookup stays disabled; the R code may name the routines by symbol or by string. A C routine with the name of a Zig export is not registered (a message says so when the package loads). use_rzig() with mixed = TRUE calls this function before it scaffolds the package.

Examples

package_path <- tempfile("rzig-mixed-", tmpdir = tempdir())
dir.create(package_path)
writeLines(c("Package: examplepkg", "Version: 0.0.1"),
  file.path(package_path, "DESCRIPTION"))
use_rzig_mixed(package_path)
#> Package examplepkg builds its C, C++ and Fortran sources next to the Zig code
read.dcf(file.path(package_path, "DESCRIPTION"), fields = "Config/rzig/mixed")
#>      Config/rzig/mixed
#> [1,] "true"           
unlink(package_path, recursive = TRUE)