charToRaw and charToRaw Rcpp implementation.

raw_char.cpp

// [[Rcpp::plugins(cpp17)]]
#include <Rcpp.h>

// [[Rcpp::export(rng = false)]]
Rcpp::RawVector Cpp_charToRaw1(const std::string& s) {
  Rcpp::RawVector res(s.begin(), s.end());
  return res;
}

// [[Rcpp::export(rng = false)]]
Rcpp::RawVector Cpp_charToRaw2(const char* s) {
  Rcpp::RawVector res(s, s + std::strlen(s));
  return res;
}

// [[Rcpp::export(rng = false)]]
std::vector<unsigned char> Cpp_charToRaw3(const char* s) {
  std::vector<unsigned char> res(s, s + std::strlen(s));
  return res;
}

// [[Rcpp::export(rng = false)]]
std::vector<unsigned char> Cpp_charToRaw4(const char* s) {
  std::string_view sv(s);
  std::vector<unsigned char> res(sv.begin(), sv.end());
  return res;
}

// [[Rcpp::export(rng = false)]]
Rcpp::RawVector Cpp_charToRaw5(const char* s) {
  std::string_view sv(s);
  Rcpp::RawVector res(sv.begin(), sv.end());
  return res;
}

// [[Rcpp::export(rng = false)]]
std::string Cpp_rawToChar1(Rcpp::RawVector x) {
  std::string out(reinterpret_cast<const char*>(x.begin()), x.size());
  return out;
}

// [[Rcpp::export(rng = false)]]
std::string Cpp_rawToChar2(Rcpp::RawVector x) {
  std::string out((x.begin()), x.end());
  return out;
}

// [[Rcpp::export(rng=false)]]
std::string Cpp_rawToChar3(const std::vector<unsigned char>& x) {
  return std::string(x.begin(), x.end());
}

// [[Rcpp::export(rng=false)]]
const char* Cpp_rawToChar4(const std::vector<unsigned char>& x) {
  const char* res = reinterpret_cast<const char*>(x.data());
  return res;
}

/***R
s = "Test string. Test string. Test string. Test string."
bench::mark(
  Cpp_charToRaw1(s),
  Cpp_charToRaw2(s),
  Cpp_charToRaw3(s),
  Cpp_charToRaw4(s),
  Cpp_charToRaw5(s),
  charToRaw(s),
  iterations = 100000
)
r = charToRaw(s)
bench::mark(
  Cpp_rawToChar1(r),
  Cpp_rawToChar2(r),
  Cpp_rawToChar3(r),
  Cpp_rawToChar4(r),
  rawToChar(r),
  iterations = 100000
)
*/

> s = "Test string. Test string. Test string. Test string."

> bench::mark(
+   Cpp_charToRaw1(s),
+   Cpp_charToRaw2(s),
+   Cpp_charToRaw3(s),
+   Cpp_charToRaw4(s),
+   Cpp_charToRaw5(s),
+   charToRaw(s),
+  .... [TRUNCATED] 
# A tibble: 6 x 13
  expression          min median `itr/sec` mem_alloc `gc/sec`  n_itr  n_gc total_time result
  <bch:expr>        <bch> <bch:>     <dbl> <bch:byt>    <dbl>  <int> <dbl>   <bch:tm> <list>
1 Cpp_charToRaw1(s) 633ns  703ns  1081646.        0B      0   100000     0     92.5ms < [51…
2 Cpp_charToRaw2(s) 525ns  596ns  1475564.        0B      0   100000     0     67.8ms < [51…
3 Cpp_charToRaw3(s) 579ns  645ns  1314849.        0B      0   100000     0     76.1ms < [51…
4 Cpp_charToRaw4(s) 569ns  637ns  1457694.        0B      0   100000     0     68.6ms < [51…
5 Cpp_charToRaw5(s) 522ns  584ns  1582075.        0B     15.8  99999     1     63.2ms < [51…
6 charToRaw(s)      382ns  442ns  2075378.        0B      0   100000     0     48.2ms < [51…
# … with 3 more variables: memory <list>, time <list>, gc <list>

> r = charToRaw(s)

> bench::mark(
+   Cpp_rawToChar1(r),
+   Cpp_rawToChar2(r),
+   Cpp_rawToChar3(r),
+   Cpp_rawToChar4(r),
+   rawToChar(r),
+   iterations = 100000
+ .... [TRUNCATED] 
# A tibble: 5 x 13
  expression          min median `itr/sec` mem_alloc `gc/sec`  n_itr  n_gc total_time result
  <bch:expr>        <bch> <bch:>     <dbl> <bch:byt>    <dbl>  <int> <dbl>   <bch:tm> <list>
1 Cpp_rawToChar1(r) 735ns  804ns  1114922.        0B      0   100000     0     89.7ms <chr …
2 Cpp_rawToChar2(r) 742ns  799ns  1136085.        0B     11.4  99999     1       88ms <chr …
3 Cpp_rawToChar3(r) 778ns  832ns  1127151.        0B      0   100000     0     88.7ms <chr …
4 Cpp_rawToChar4(r) 744ns  802ns  1139719.        0B     11.4  99999     1     87.7ms <chr …
5 rawToChar(r)      713ns  767ns  1188818.        0B      0   100000     0     84.1ms <chr …
# … with 3 more variables: memory <list>, time <list>, gc <list>
>