cpp11/inst/include/cpp11/attribute_proxy.hpp at master · tmastny/cpp11 · GitHub

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#pragma once

#include <initializer_list> // for initializer_list

#include <string> // for string, basic_string

#include "cpp11/R.hpp" // for SEXP, SEXPREC, Rf_install, PROTECT, Rf_...

#include "cpp11/as.hpp" // for as_sexp

#include "cpp11/protect.hpp" // for protect, safe, protect::function

namespace cpp11 {

class sexp;

template <typename T>

class attribute_proxy {

private:

const T& parent_;

SEXP symbol_;

public:

attribute_proxy(const T& parent, const char* index)

: parent_(parent), symbol_(safe[Rf_install](index)) {}

attribute_proxy(const T& parent, const std::string& index)

: parent_(parent), symbol_(safe[Rf_install](index.c_str())) {}

attribute_proxy(const T& parent, SEXP index) : parent_(parent), symbol_(index) {}

template <typename C>

attribute_proxy& operator=(C rhs) {

SEXP value = PROTECT(as_sexp(rhs));

Rf_setAttrib(parent_.data(), symbol_, value);

UNPROTECT(1);

return *this;

}

template <typename C>

attribute_proxy& operator=(std::initializer_list<C> rhs) {

SEXP value = PROTECT(as_sexp(rhs));

Rf_setAttrib(parent_.data(), symbol_, value);

UNPROTECT(1);

return *this;

}

operator SEXP() const { return safe[Rf_getAttrib](parent_.data(), symbol_); }

};

} // namespace cpp11

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