na_locf.cpp

// [[Rcpp::plugins(cpp11)]]

#include <Rcpp.h>

using namespace Rcpp;

template <int RTYPE>
Vector<RTYPE> na_locf_impl(Vector<RTYPE> x) {
    std::size_t n = x.size();
    auto v = x[0];
    for (std::size_t i = 0; i < n; ++i) {
        if (Vector<RTYPE>::is_na(x[i]))
            x[i] = v;
        else
            v = x[i];
    }
    return x;
}

// [[Rcpp::export]]
SEXP na_locf(SEXP x) {
    RCPP_RETURN_VECTOR(na_locf_impl, x);
}