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handle enum with underlying type char #74

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Merged
jimhester merged 2 commits into from
Aug 6, 2020
Merged

handle enum with underlying type char #74

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dbcc8c5
handle enum with underlying type char
romainfrancois Aug 5, 2020
a451f4b
Update inst/include/cpp11/as.hpp
romainfrancois Aug 6, 2020
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13 changes: 13 additions & 0 deletions cpp11test/src/test-as.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -90,6 +90,19 @@ context("as_cpp-C++") {
UNPROTECT(1);
}

test_that("as_cpp<enum:char>(INTSEXP)") {
enum class Response: char { YES, NO, MAYBE };
SEXP r = PROTECT(Rf_allocVector(INTSXP, 1));

for (Response e : {Response::YES, Response::NO, Response::MAYBE, static_cast<Response>(42)}) {
INTEGER(r)[0] = static_cast<int>(e);
auto x = cpp11::as_cpp<Response>(r);
expect_true(x == e);
}

UNPROTECT(1);
}

test_that("as_cpp<double>(REALSXP)") {
SEXP r = PROTECT(Rf_allocVector(REALSXP, 1));
REAL(r)[0] = 1.2;
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8 changes: 7 additions & 1 deletion inst/include/cpp11/as.hpp
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Expand Up @@ -96,7 +96,13 @@ enable_if_integral<T, T> as_cpp(SEXP from) {
template <typename E>
enable_if_enum<E, E> as_cpp(SEXP from) {
if (Rf_isInteger(from)) {
return static_cast<E>(as_cpp<typename std::underlying_type<E>::type>(from));
using underlying_type = typename std::underlying_type<E>::type;
using int_type = typename std::conditional<
std::is_same<char, underlying_type>::value,
int, // as_cpp<char> would trigger undesired string conversions
underlying_type
>::type;
return static_cast<E>(as_cpp<int_type>(from));
}

stop("Expected single integer value");
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