1 files changed, 75 insertions, 0 deletions
diff --git a/src/arrow/r/inst/include/cpp11/environment.hpp b/src/arrow/r/inst/include/cpp11/environment.hpp
new file mode 100644
index 000000000..038fb60a8
--- /dev/null
+++ b/src/arrow/r/inst/include/cpp11/environment.hpp
@@ -0,0 +1,75 @@
+// cpp11 version: 0.3.1.1
+// vendored on: 2021-08-11
+#pragma once
+
+#include <string>  // for string, basic_string
+
+#include "Rversion.h"         // for R_VERSION, R_Version
+#include "cpp11/R.hpp"        // for SEXP, SEXPREC, Rf_install, Rf_findVarIn...
+#include "cpp11/as.hpp"       // for as_sexp
+#include "cpp11/protect.hpp"  // for protect, protect::function, safe, unwin...
+#include "cpp11/sexp.hpp"     // for sexp
+
+#if R_VERSION >= R_Version(4, 0, 0)
+#define HAS_REMOVE_VAR_FROM_FRAME
+#endif
+
+#ifndef HAS_REMOVE_VAR_FROM_FRAME
+#include "cpp11/function.hpp"
+#endif
+
+namespace cpp11 {
+
+class environment {
+ private:
+  sexp env_;
+
+  class proxy {
+    SEXP parent_;
+    SEXP name_;
+
+   public:
+    proxy(SEXP parent, SEXP name) : parent_(parent), name_(name) {}
+
+    template <typename T>
+    proxy& operator=(T value) {
+      safe[Rf_defineVar](name_, as_sexp(value), parent_);
+      return *this;
+    }
+    operator SEXP() const { return safe[Rf_findVarInFrame3](parent_, name_, TRUE); };
+    operator sexp() const { return SEXP(); };
+  };
+
+ public:
+  environment(SEXP env) : env_(env) {}
+  proxy operator[](SEXP name) const { return {env_, name}; }
+  proxy operator[](const char* name) const { return operator[](safe[Rf_install](name)); }
+  proxy operator[](const std::string& name) const { return operator[](name.c_str()); }
+
+  bool exists(SEXP name) const {
+    SEXP res = safe[Rf_findVarInFrame3](env_, name, FALSE);
+    return res != R_UnboundValue;
+  }
+  bool exists(const char* name) const { return exists(safe[Rf_install](name)); }
+
+  bool exists(const std::string& name) const { return exists(name.c_str()); }
+
+  void remove(SEXP name) {
+    PROTECT(name);
+#ifdef HAS_REMOVE_VAR_FROM_FRAME
+    R_removeVarFromFrame(name, env_);
+#else
+    auto remove = package("base")["remove"];
+    remove(name, "envir"_nm = env_);
+#endif
+    UNPROTECT(1);
+  }
+
+  void remove(const char* name) { remove(safe[Rf_install](name)); }
+
+  R_xlen_t size() const { return Rf_xlength(env_); }
+
+  operator SEXP() const { return env_; }
+};
+
+}  // namespace cpp11