ceph/src/arrow/r/inst/include/cpp11/attribute_proxy.hpp

   1 // cpp11 version: 0.3.1.1
   2 // vendored on: 2021-08-11
   3 #pragma once
   4
   5 #include <initializer_list>  // for initializer_list
   6 #include <string>            // for string, basic_string
   7
   8 #include "cpp11/R.hpp"        // for SEXP, SEXPREC, Rf_install, PROTECT, Rf_...
   9 #include "cpp11/as.hpp"       // for as_sexp
  10 #include "cpp11/protect.hpp"  // for protect, safe, protect::function
  11
  12 namespace cpp11 {
  13
  14 class sexp;
  15
  16 template <typename T>
  17 class attribute_proxy {
  18  private:
  19   const T& parent_;
  20   SEXP symbol_;
  21
  22  public:
  23   attribute_proxy(const T& parent, const char* index)
  24       : parent_(parent), symbol_(safe[Rf_install](index)) {}
  25
  26   attribute_proxy(const T& parent, const std::string& index)
  27       : parent_(parent), symbol_(safe[Rf_install](index.c_str())) {}
  28
  29   attribute_proxy(const T& parent, SEXP index) : parent_(parent), symbol_(index) {}
  30
  31   template <typename C>
  32   attribute_proxy& operator=(C rhs) {
  33     SEXP value = PROTECT(as_sexp(rhs));
  34     Rf_setAttrib(parent_.data(), symbol_, value);
  35     UNPROTECT(1);
  36     return *this;
  37   }
  38
  39   template <typename C>
  40   attribute_proxy& operator=(std::initializer_list<C> rhs) {
  41     SEXP value = PROTECT(as_sexp(rhs));
  42     Rf_setAttrib(parent_.data(), symbol_, value);
  43     UNPROTECT(1);
  44     return *this;
  45   }
  46
  47   operator SEXP() const { return safe[Rf_getAttrib](parent_.data(), symbol_); }
  48 };
  49
  50 }  // namespace cpp11