--- /dev/null
+// cpp11 version: 0.3.1.1
+// vendored on: 2021-08-11
+#pragma once
+
+#include <csetjmp> // for longjmp, setjmp, jmp_buf
+#include <exception> // for exception
+#include <stdexcept> // for std::runtime_error
+#include <string> // for string, basic_string
+#include <tuple> // for tuple, make_tuple
+
+// NB: cpp11/R.hpp must precede R_ext/Error.h to ensure R_NO_REMAP is defined
+#include "cpp11/R.hpp" // for SEXP, SEXPREC, CDR, R_NilValue, CAR, R_Pres...
+
+#include "R_ext/Boolean.h" // for Rboolean
+#include "R_ext/Error.h" // for Rf_error, Rf_warning
+#include "R_ext/Print.h" // for REprintf
+#include "R_ext/Utils.h" // for R_CheckUserInterrupt
+#include "Rversion.h" // for R_VERSION, R_Version
+
+#if defined(R_VERSION) && R_VERSION >= R_Version(3, 5, 0)
+#define HAS_UNWIND_PROTECT
+#endif
+
+namespace cpp11 {
+class unwind_exception : public std::exception {
+ public:
+ SEXP token;
+ unwind_exception(SEXP token_) : token(token_) {}
+};
+
+#ifdef HAS_UNWIND_PROTECT
+
+/// Unwind Protection from C longjmp's, like those used in R error handling
+///
+/// @param code The code to which needs to be protected, as a nullary callable
+template <typename Fun, typename = typename std::enable_if<std::is_same<
+ decltype(std::declval<Fun&&>()()), SEXP>::value>::type>
+SEXP unwind_protect(Fun&& code) {
+ static SEXP token = [] {
+ SEXP res = R_MakeUnwindCont();
+ R_PreserveObject(res);
+ return res;
+ }();
+
+ std::jmp_buf jmpbuf;
+ if (setjmp(jmpbuf)) {
+ throw unwind_exception(token);
+ }
+
+ SEXP res = R_UnwindProtect(
+ [](void* data) -> SEXP {
+ auto callback = static_cast<decltype(&code)>(data);
+ return static_cast<Fun&&>(*callback)();
+ },
+ &code,
+ [](void* jmpbuf, Rboolean jump) {
+ if (jump == TRUE) {
+ // We need to first jump back into the C++ stacks because you can't safely throw
+ // exceptions from C stack frames.
+ longjmp(*static_cast<std::jmp_buf*>(jmpbuf), 1);
+ }
+ },
+ &jmpbuf, token);
+
+ // R_UnwindProtect adds the result to the CAR of the continuation token,
+ // which implicitly protects the result. However if there is no error and
+ // R_UwindProtect does a normal exit the memory shouldn't be protected, so we
+ // unset it here before returning the value ourselves.
+ SETCAR(token, R_NilValue);
+
+ return res;
+}
+
+template <typename Fun, typename = typename std::enable_if<std::is_same<
+ decltype(std::declval<Fun&&>()()), void>::value>::type>
+void unwind_protect(Fun&& code) {
+ (void)unwind_protect([&] {
+ std::forward<Fun>(code)();
+ return R_NilValue;
+ });
+}
+
+template <typename Fun, typename R = decltype(std::declval<Fun&&>()())>
+typename std::enable_if<!std::is_same<R, SEXP>::value && !std::is_same<R, void>::value,
+ R>::type
+unwind_protect(Fun&& code) {
+ R out;
+ (void)unwind_protect([&] {
+ out = std::forward<Fun>(code)();
+ return R_NilValue;
+ });
+ return out;
+}
+
+#else
+// Don't do anything if we don't have unwind protect. This will leak C++ resources,
+// including those held by cpp11 objects, but the other alternatives are also not great.
+template <typename Fun>
+decltype(std::declval<Fun&&>()()) unwind_protect(Fun&& code) {
+ return std::forward<Fun>(code)();
+}
+#endif
+
+namespace detail {
+
+template <size_t...>
+struct index_sequence {
+ using type = index_sequence;
+};
+
+template <typename, size_t>
+struct appended_sequence;
+
+template <std::size_t... I, std::size_t J>
+struct appended_sequence<index_sequence<I...>, J> : index_sequence<I..., J> {};
+
+template <size_t N>
+struct make_index_sequence
+ : appended_sequence<typename make_index_sequence<N - 1>::type, N - 1> {};
+
+template <>
+struct make_index_sequence<0> : index_sequence<> {};
+
+template <typename F, typename... Aref, size_t... I>
+decltype(std::declval<F&&>()(std::declval<Aref>()...)) apply(
+ F&& f, std::tuple<Aref...>&& a, const index_sequence<I...>&) {
+ return std::forward<F>(f)(std::get<I>(std::move(a))...);
+}
+
+template <typename F, typename... Aref>
+decltype(std::declval<F&&>()(std::declval<Aref>()...)) apply(F&& f,
+ std::tuple<Aref...>&& a) {
+ return apply(std::forward<F>(f), std::move(a), make_index_sequence<sizeof...(Aref)>{});
+}
+
+// overload to silence a compiler warning that the (empty) tuple parameter is set but
+// unused
+template <typename F>
+decltype(std::declval<F&&>()()) apply(F&& f, std::tuple<>&&) {
+ return std::forward<F>(f)();
+}
+
+template <typename F, typename... Aref>
+struct closure {
+ decltype(std::declval<F*>()(std::declval<Aref>()...)) operator()() && {
+ return apply(ptr_, std::move(arefs_));
+ }
+ F* ptr_;
+ std::tuple<Aref...> arefs_;
+};
+
+} // namespace detail
+
+struct protect {
+ template <typename F>
+ struct function {
+ template <typename... A>
+ decltype(std::declval<F*>()(std::declval<A&&>()...)) operator()(A&&... a) const {
+ // workaround to support gcc4.8, which can't capture a parameter pack
+ return unwind_protect(
+ detail::closure<F, A&&...>{ptr_, std::forward_as_tuple(std::forward<A>(a)...)});
+ }
+
+ F* ptr_;
+ };
+
+ /// May not be applied to a function bearing attributes, which interfere with linkage on
+ /// some compilers; use an appropriately attributed alternative. (For example, Rf_error
+ /// bears the [[noreturn]] attribute and must be protected with safe.noreturn rather
+ /// than safe.operator[]).
+ template <typename F>
+ constexpr function<F> operator[](F* raw) const {
+ return {raw};
+ }
+
+ template <typename F>
+ struct noreturn_function {
+ template <typename... A>
+ void operator() [[noreturn]] (A&&... a) const {
+ // workaround to support gcc4.8, which can't capture a parameter pack
+ unwind_protect(
+ detail::closure<F, A&&...>{ptr_, std::forward_as_tuple(std::forward<A>(a)...)});
+ // Compiler hint to allow [[noreturn]] attribute; this is never executed since
+ // the above call will not return.
+ throw std::runtime_error("[[noreturn]]");
+ }
+ F* ptr_;
+ };
+
+ template <typename F>
+ constexpr noreturn_function<F> noreturn(F* raw) const {
+ return {raw};
+ }
+};
+constexpr struct protect safe = {};
+
+inline void check_user_interrupt() { safe[R_CheckUserInterrupt](); }
+
+template <typename... Args>
+void stop [[noreturn]] (const char* fmt, Args... args) {
+ safe.noreturn(Rf_errorcall)(R_NilValue, fmt, args...);
+}
+
+template <typename... Args>
+void stop [[noreturn]] (const std::string& fmt, Args... args) {
+ safe.noreturn(Rf_errorcall)(R_NilValue, fmt.c_str(), args...);
+}
+
+template <typename... Args>
+void warning(const char* fmt, Args... args) {
+ safe[Rf_warningcall](R_NilValue, fmt, args...);
+}
+
+template <typename... Args>
+void warning(const std::string& fmt, Args... args) {
+ safe[Rf_warningcall](R_NilValue, fmt.c_str(), args...);
+}
+
+/// A doubly-linked list of preserved objects, allowing O(1) insertion/release of
+/// objects compared to O(N preserved) with R_PreserveObject.
+static struct {
+ SEXP insert(SEXP obj) {
+ if (obj == R_NilValue) {
+ return R_NilValue;
+ }
+
+#ifdef CPP11_USE_PRESERVE_OBJECT
+ PROTECT(obj);
+ R_PreserveObject(obj);
+ UNPROTECT(1);
+ return obj;
+#endif
+
+ PROTECT(obj);
+
+ SEXP list_ = get_preserve_list();
+
+ // Add a new cell that points to the previous end.
+ SEXP cell = PROTECT(Rf_cons(list_, CDR(list_)));
+
+ SET_TAG(cell, obj);
+
+ SETCDR(list_, cell);
+
+ if (CDR(cell) != R_NilValue) {
+ SETCAR(CDR(cell), cell);
+ }
+
+ UNPROTECT(2);
+
+ return cell;
+ }
+
+ void print() {
+ for (SEXP head = get_preserve_list(); head != R_NilValue; head = CDR(head)) {
+ REprintf("%x CAR: %x CDR: %x TAG: %x\n", head, CAR(head), CDR(head), TAG(head));
+ }
+ REprintf("---\n");
+ }
+
+ // This is currently unused, but client packages could use it to free leaked resources
+ // in older R versions if needed
+ void release_all() {
+#if !defined(CPP11_USE_PRESERVE_OBJECT)
+ SEXP list_ = get_preserve_list();
+ SEXP first = CDR(list_);
+ if (first != R_NilValue) {
+ SETCAR(first, R_NilValue);
+ SETCDR(list_, R_NilValue);
+ }
+#endif
+ }
+
+ void release(SEXP token) {
+ if (token == R_NilValue) {
+ return;
+ }
+
+#ifdef CPP11_USE_PRESERVE_OBJECT
+ R_ReleaseObject(token);
+ return;
+#endif
+
+ SEXP before = CAR(token);
+
+ SEXP after = CDR(token);
+
+ if (before == R_NilValue && after == R_NilValue) {
+ Rf_error("should never happen");
+ }
+
+ SETCDR(before, after);
+
+ if (after != R_NilValue) {
+ SETCAR(after, before);
+ }
+ }
+
+ private:
+ // We deliberately avoid using safe[] in the below code, as this code runs
+ // when the shared library is loaded and will not be wrapped by
+ // `CPP11_UNWIND`, so if an error occurs we will not catch the C++ exception
+ // that safe emits.
+ static void set_option(SEXP name, SEXP value) {
+ static SEXP opt = SYMVALUE(Rf_install(".Options"));
+ SEXP t = opt;
+ while (CDR(t) != R_NilValue) {
+ if (TAG(CDR(t)) == name) {
+ opt = CDR(t);
+ SET_TAG(opt, name);
+ SETCAR(opt, value);
+ return;
+ }
+ t = CDR(t);
+ }
+ SETCDR(t, Rf_allocList(1));
+ opt = CDR(t);
+ SET_TAG(opt, name);
+ SETCAR(opt, value);
+ }
+
+ // The preserved list singleton is stored in a XPtr within an R global option.
+ //
+ // It is not constructed as a static variable directly since many
+ // translation units may be compiled, resulting in unrelated instances of each
+ // static variable.
+ //
+ // We cannot store it in the cpp11 namespace, as cpp11 likely will not be loaded by
+ // packages.
+ // We cannot store it in R's global environment, as that is against CRAN
+ // policies.
+ // We instead store it as an XPtr in the global options, which avoids issues
+ // both copying and serializing.
+ static SEXP get_preserve_xptr_addr() {
+ static SEXP preserve_xptr_sym = Rf_install("cpp11_preserve_xptr");
+ SEXP preserve_xptr = Rf_GetOption1(preserve_xptr_sym);
+
+ if (TYPEOF(preserve_xptr) != EXTPTRSXP) {
+ return R_NilValue;
+ }
+ auto addr = R_ExternalPtrAddr(preserve_xptr);
+ if (addr == nullptr) {
+ return R_NilValue;
+ }
+ return static_cast<SEXP>(addr);
+ }
+
+ static void set_preserve_xptr(SEXP value) {
+ static SEXP preserve_xptr_sym = Rf_install("cpp11_preserve_xptr");
+
+ SEXP xptr = PROTECT(R_MakeExternalPtr(value, R_NilValue, R_NilValue));
+ set_option(preserve_xptr_sym, xptr);
+ UNPROTECT(1);
+ }
+
+ static SEXP get_preserve_list() {
+ static SEXP preserve_list = R_NilValue;
+
+ if (TYPEOF(preserve_list) != LISTSXP) {
+ preserve_list = get_preserve_xptr_addr();
+ if (TYPEOF(preserve_list) != LISTSXP) {
+ preserve_list = Rf_cons(R_NilValue, R_NilValue);
+ R_PreserveObject(preserve_list);
+ set_preserve_xptr(preserve_list);
+ }
+ }
+
+ return preserve_list;
+ }
+} // namespace cpp11
+preserved;
+} // namespace cpp11
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