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@traversc
Last active Jan 15, 2019
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alt rep string test
#include <iostream>
#include "altrepisode.h"
#include <string>
#include <vector>
std::string getRandomStrings(int seed, int len = 30) {
std::srand(static_cast<unsigned int>(seed));
static const char alphanum[] =
"0123456789"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz";
std::string s(len, '\0');
for (int i = 0; i < len; ++i) {
s[i] = alphanum[rand() % (sizeof(alphanum) - 1)];
}
return s;
}
struct random_string_data {
int N;
random_string_data(int n) : N(n) {}
};
struct alt_random_string {
static R_altrep_class_t class_t;
// constructor function
static SEXP Make(random_string_data* data, bool owner){
SEXP xp = PROTECT(R_MakeExternalPtr(data, R_NilValue, R_NilValue));
if (owner) {
R_RegisterCFinalizerEx(xp, alt_random_string::Finalize, TRUE);
}
SEXP res = R_new_altrep(class_t, xp, R_NilValue);
UNPROTECT(1);
return res;
}
// finalizer for the external pointer
static void Finalize(SEXP xp){
delete static_cast<random_string_data*>(R_ExternalPtrAddr(xp));
}
// get the std::vector<string>* from the altrep object `x`
static random_string_data* Ptr(SEXP x) {
return static_cast<random_string_data*>(R_ExternalPtrAddr(R_altrep_data1(x)));
}
// same, but as a reference, for convenience
static random_string_data& Get(SEXP vec) {
return *Ptr(vec) ;
}
// ALTREP methods -------------------
// The length of the object
static R_xlen_t Length(SEXP vec){
return Get(vec).N;
}
// What gets printed when .Internal(inspect()) is used
static Rboolean Inspect(SEXP x, int pre, int deep, int pvec, void (*inspect_subtree)(SEXP, int, int, int)){
Rprintf("random_string_data (len=%d, ptr=%p)\n", Length(x), Ptr(x));
return TRUE;
}
// ALTVEC methods ------------------
static SEXP Materialize(SEXP vec) {
std::cout << "Materialize method called\n";
SEXP data2 = R_altrep_data2(vec);
if (data2 != R_NilValue) {
return data2;
}
R_xlen_t n = Length(vec);
data2 = PROTECT(Rf_allocVector(STRSXP, n));
auto data1 = Get(vec);
for (R_xlen_t i = 0; i < n; i++) {
std::string mystring = getRandomStrings(i);
SET_STRING_ELT(data2, i, Rf_mkCharLen(mystring.data(), mystring.size()) );
}
R_set_altrep_data2(vec, data2);
UNPROTECT(1);
return data2;
}
// The start of the data, i.e. the underlying string array from the random_string_data
//
// This is guaranteed to never allocate (in the R sense)
static const void* Dataptr_or_null(SEXP vec) {
SEXP data2 = R_altrep_data2(vec);
if (data2 == R_NilValue) return nullptr;
return STDVEC_DATAPTR(data2);
}
// same in this case, writeable is ignored
static void* Dataptr(SEXP vec, Rboolean writeable) {
return STDVEC_DATAPTR(Materialize(vec));
}
// ALTSTRING methods -----------------
// the element at the index `i`
// this does not do bounds checking because that's expensive, so
// the caller must take care of that
static SEXP string_Elt(SEXP vec, R_xlen_t i){
std::cout << i << "\n";
std::string mystring = getRandomStrings(i);
return Rf_mkCharLen(mystring.data(), mystring.size());
}
// -------- initialize the altrep class with the methods above
static void Init(DllInfo* dll){
class_t = R_make_altstring_class("alt_random_string", "altstringisode", dll);
// altrep
R_set_altrep_Length_method(class_t, Length);
R_set_altrep_Inspect_method(class_t, Inspect);
// altvec
R_set_altvec_Dataptr_method(class_t, Dataptr);
R_set_altvec_Dataptr_or_null_method(class_t, Dataptr_or_null);
// altstring
R_set_altstring_Elt_method(class_t, string_Elt);
}
};
// static initialization of stdvec_double::class_t
R_altrep_class_t alt_random_string::class_t;
// Called the package is loaded (needs Rcpp 0.12.18.3)
// [[Rcpp::init]]
void init_stdvec_double(DllInfo* dll){
alt_random_string::Init(dll);
}
// [[Rcpp::export]]
SEXP altrandomStrings(int N) {
auto x = new random_string_data(N);
return alt_random_string::Make(x, true);
}
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