Implement hello2

Author: yutannihilation

R/hello.R

@@ -10,6 +10,14 @@ hello <- function() {
   .Call(hello_wrapper)
 }
 
+#' @export
+#' @rdname hellorust
+#' @examples hello()
+#' @useDynLib hellorust hello_wrapper2
+hello2 <- function(name) {
+  .Call(hello_wrapper2, name)
+}
+
 #' @export
 #' @rdname hellorust
 #' @examples random()

src/myrustlib/api.h

@@ -5,6 +5,7 @@ extern "C" {
 #endif
 
 char * string_from_rust();
+char * string_from_rust2(const char*);
 int32_t random_number();
 void run_threads();
 

src/myrustlib/src/hello.rs

@@ -1,5 +1,5 @@
 use std;
-use std::ffi::CString;
+use std::ffi::{CStr, CString};
 use std::os::raw::c_char;
 
 #[no_mangle]
@@ -9,3 +9,18 @@ pub extern fn string_from_rust() -> *const c_char {
     std::mem::forget(s);
     p
 }
+
+// Utility function to convert c_char to string
+fn c_char_to_string(c: *const c_char) -> String {
+    unsafe { CStr::from_ptr(c).to_string_lossy().into_owned() }
+}
+
+#[no_mangle]
+pub extern fn string_from_rust2(c_name: *const c_char) -> *const c_char {
+    let name = c_char_to_string(c_name);
+
+    let s = CString::new(format!("Hello {} !", name)).unwrap();
+    let p = s.as_ptr();
+    std::mem::forget(s);
+    p
+}

src/wrapper.c

@@ -10,6 +10,12 @@ SEXP hello_wrapper(){
   return Rf_ScalarString(Rf_mkCharCE(string_from_rust(), CE_UTF8));
 }
 
+SEXP hello_wrapper2(SEXP name){
+  char* res = string_from_rust2(Rf_translateCharUTF8(STRING_ELT(name, 0)));
+  return Rf_ScalarString(Rf_mkCharCE(res, CE_UTF8));
+}
+
+
 SEXP random_wrapper(){
   return Rf_ScalarInteger(random_number());
 }
@@ -22,6 +28,7 @@ SEXP threads_wapper(){
 // Standard R package stuff
 static const R_CallMethodDef CallEntries[] = {
   {"hello_wrapper", (DL_FUNC) &hello_wrapper, 0},
+  {"hello_wrapper2", (DL_FUNC) &hello_wrapper2, 0},
   {"random_wrapper", (DL_FUNC) &random_wrapper, 0},
   {"threads_wapper", (DL_FUNC) &threads_wapper, 0},
   {NULL, NULL, 0}