Implementation of a hex string conversion

[lamium2]

Hello, I wanted to store xxhash64 strings as integer64 and was surprised that there is no function that can convert hex strings directly to integer64.

As a workaround, I wrote a Rcpp function:

cppFunction('
NumericVector hex_to_int64_cpp(CharacterVector hex_strings) {
  int n = hex_strings.size();
  NumericVector out(n);
  
  for(int i = 0; i < n; ++i) {
    if (CharacterVector::is_na(hex_strings[i])) {
      out[i] = NA_REAL;
    } else {
      const char* s = hex_strings[i];
      char* endptr;
      unsigned long long val = std::strtoull(s, &endptr, 16);
      ((unsigned long long*)out.begin())[i] = val;
    }
  }
  out.attr("class") = "integer64";
  return out;
}
')

In my opinion, such a function would be quite practical for efficiently storing 64-bit hashes created with digest. Perhaps this could be an idea for a new feature. Thanks!

[MichaelChirico]

could you check on the development version of bit64? as.character should now support this directly