1 files changed, 78 insertions, 0 deletions
diff --git a/src/arrow/r/inst/include/cpp11/function.hpp b/src/arrow/r/inst/include/cpp11/function.hpp
new file mode 100644
index 000000000..06e602ac6
--- /dev/null
+++ b/src/arrow/r/inst/include/cpp11/function.hpp
@@ -0,0 +1,78 @@
+// cpp11 version: 0.3.1.1
+// vendored on: 2021-08-11
+#pragma once
+
+#include <string.h>  // for strcmp
+
+#include <string>   // for string, basic_string
+#include <utility>  // for forward
+
+#include "cpp11/R.hpp"          // for SEXP, SEXPREC, CDR, Rf_install, SETCAR
+#include "cpp11/as.hpp"         // for as_sexp
+#include "cpp11/named_arg.hpp"  // for named_arg
+#include "cpp11/protect.hpp"    // for protect, protect::function, safe
+#include "cpp11/sexp.hpp"       // for sexp
+
+namespace cpp11 {
+
+class function {
+ public:
+  function(SEXP data) : data_(data) {}
+
+  template <typename... Args>
+  sexp operator()(Args&&... args) const {
+    // Size of the arguments plus one for the function name itself
+    R_xlen_t num_args = sizeof...(args) + 1;
+
+    sexp call(safe[Rf_allocVector](LANGSXP, num_args));
+
+    construct_call(call, data_, std::forward<Args>(args)...);
+
+    return safe[Rf_eval](call, R_GlobalEnv);
+  }
+
+ private:
+  SEXP data_;
+
+  template <typename... Args>
+  SEXP construct_call(SEXP val, const named_arg& arg, Args&&... args) const {
+    SETCAR(val, arg.value());
+    SET_TAG(val, safe[Rf_install](arg.name()));
+    val = CDR(val);
+    return construct_call(val, std::forward<Args>(args)...);
+  }
+
+  // Construct the call recursively, each iteration adds an Arg to the pairlist.
+  // We need
+  template <typename T, typename... Args>
+  SEXP construct_call(SEXP val, const T& arg, Args&&... args) const {
+    SETCAR(val, as_sexp(arg));
+    val = CDR(val);
+    return construct_call(val, std::forward<Args>(args)...);
+  }
+
+  // Base case, just return
+  SEXP construct_call(SEXP val) const { return val; }
+};
+
+class package {
+ public:
+  package(const char* name) : data_(get_namespace(name)) {}
+  package(const std::string& name) : data_(get_namespace(name.c_str())) {}
+  function operator[](const char* name) {
+    return safe[Rf_findFun](safe[Rf_install](name), data_);
+  }
+  function operator[](const std::string& name) { return operator[](name.c_str()); }
+
+ private:
+  static SEXP get_namespace(const char* name) {
+    if (strcmp(name, "base") == 0) {
+      return R_BaseEnv;
+    }
+    sexp name_sexp = safe[Rf_install](name);
+    return safe[Rf_findVarInFrame](R_NamespaceRegistry, name_sexp);
+  }
+
+  SEXP data_;
+};
+}  // namespace cpp11