Fix portability to windows by replacing std::itoa with std::generate

Author: xiamx

src/fasttext.cc

@@ -195,7 +195,8 @@ std::vector<int32_t> FastText::selectEmbeddings(int32_t cutoff) const {
   Vector norms(input_->m_);
   input_->l2NormRow(norms);
   std::vector<int32_t> idx(input_->m_, 0);
-  std::iota(idx.begin(), idx.end(), 0);
+  int n = { 0 };
+  std::generate(idx.begin(), idx.end(), [&n] {return ++n; });
   auto eosid = dict_->getId(Dictionary::EOS);
   std::sort(idx.begin(), idx.end(),
       [&norms, eosid] (size_t i1, size_t i2) {

src/productquantizer.cc

@@ -112,7 +112,8 @@ void ProductQuantizer::MStep(const real* x0, real* centroids,
 
 void ProductQuantizer::kmeans(const real *x, real* c, int32_t n, int32_t d) {
   std::vector<int32_t> perm(n,0);
-  std::iota(perm.begin(), perm.end(), 0);
+  int gn = { 0 };
+  std::generate(perm.begin(), perm.end(), [&gn] {return ++gn; });
   std::shuffle(perm.begin(), perm.end(), rng);
   for (auto i = 0; i < ksub_; i++) {
     memcpy (&c[i * d], x + perm[i] * d, d * sizeof(real));
@@ -131,7 +132,8 @@ void ProductQuantizer::train(int32_t n, const real * x) {
     exit(1);
   }
   std::vector<int32_t> perm(n, 0);
-  std::iota(perm.begin(), perm.end(), 0);
+  int gn = { 0 };
+  std::generate(perm.begin(), perm.end(), [&gn] {return ++gn; });
   auto d = dsub_;
   auto np = std::min(n, max_points_);
   real* xslice = new real[np * dsub_];