text: /**
   * Copyright (c) 2016-present, Facebook, Inc.
   * All rights reserved.
   *
   * This source code is licensed under the MIT license found in the
   * LICENSE file in the root directory of this source tree.
   */
  
  #pragma once
  
  #include <cstring>
  #include <istream>
  #include <ostream>
  #include <random>
  #include <vector>
  
  #include "real.h"
  #include "vector.h"
  #include "memstream.h"
  
  namespace fasttext {
  
  class ProductQuantizer {
   protected:
    const int32_t nbits_ = 8;
    const int32_t ksub_ = 1 << nbits_;
    const int32_t max_points_per_cluster_ = 256;
    const int32_t max_points_ = max_points_per_cluster_ * ksub_;
    const int32_t seed_ = 1234;
    const int32_t niter_ = 25;
    const real eps_ = 1e-7;
  
    int32_t dim_;
    int32_t nsubq_;
    int32_t dsub_;
    int32_t lastdsub_;
  
    std::vector<real> centroids_;
  
    std::minstd_rand rng;
  
   public:
    ProductQuantizer() {}
    ProductQuantizer(int32_t, int32_t);
  
    real* get_centroids(int32_t, uint8_t);
    const real* get_centroids(int32_t, uint8_t) const;
  
    real assign_centroid(const real*, const real*, uint8_t*, int32_t) const;
    void Estep(const real*, const real*, uint8_t*, int32_t, int32_t) const;
    void MStep(const real*, real*, const uint8_t*, int32_t, int32_t);
    void kmeans(const real*, real*, int32_t, int32_t);
    void train(int, const real*);
  
    real mulcode(const Vector&, const uint8_t*, int32_t, real) const;
    void addcode(Vector&, const uint8_t*, int32_t, real) const;
    void compute_code(const real*, uint8_t*) const;
    void compute_codes(const real*, uint8_t*, int32_t) const;
  
    void save(std::ostream&) const;
    void load(MemStream &);
  };
  
  } // namespace fasttext
  