Compile C++ code

cpp_source() compiles and loads a single C++ file for use in R. cpp_function() compiles and loads a single function for use in R. cpp_eval() evaluates a single C++ expression and returns the result.

cpp_source(
  file,
  code = NULL,
  env = parent.frame(),
  clean = TRUE,
  quiet = TRUE,
  cxx_std = Sys.getenv("CXX_STD", "CXX11"),
  dir = tempfile()
)

cpp_function(
  code,
  env = parent.frame(),
  clean = TRUE,
  quiet = TRUE,
  cxx_std = Sys.getenv("CXX_STD", "CXX11")
)

cpp_eval(
  code,
  env = parent.frame(),
  clean = TRUE,
  quiet = TRUE,
  cxx_std = Sys.getenv("CXX_STD", "CXX11")
)

Arguments

file

A file containing C++ code to compile

code

If non-null, the C++ code to compile

env

The R environment where the R wrapping functions should be defined.

clean

If TRUE, cleanup the files after sourcing

quiet

If 'TRUE`, do not show compiler output

cxx_std

The C++ standard to use, the CXX_STD make macro is set to this value. The default value queries the CXX_STD environment variable, or uses 'CXX11' if unset.

dir

The directory to store the generated source files. tempfile() is used by default. The directory will be removed if clean is TRUE.

Value

For cpp_source() and [cpp_function()] the results of dyn.load() (invisibly). For [cpp_eval()] the results of the evaluated expression.

Details

Within C++ code you can use [[cpp11::linking_to("pkgxyz")]] to link to external packages. This is equivalent to putting those packages in the LinkingTo field in a package DESCRIPTION.

Examples

cpp_source(
  code = '#include "cpp11/integers.hpp"

  [[cpp11::register]]
  int num_odd(cpp11::integers x) {
    int total = 0;
    for (int val : x) {
      if ((val % 2) == 1) {
        ++total;
      }
    }
    return total;
  }
  ')

num_odd(as.integer(c(1:10, 15, 23)))
#> [1] 7

if (interactive() && require("progress")) {

cpp_source(
  code = '
#include <cpp11/R.hpp>
#include <RProgress.h>

[[cpp11::linking_to("progress")]]

[[cpp11::register]] void
show_progress() {
  RProgress::RProgress pb("Processing [:bar] ETA: :eta");

  pb.tick(0);
  for (int i = 0; i < 100; i++) {
    usleep(2.0 / 100 * 1000000);
    pb.tick();
  }
}
')

show_progress()
}