dirichlet.h

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#ifndef META_STATS_DIRICHLET_H_
#define META_STATS_DIRICHLET_H_

#include <cstdint>
#include <memory>
#include "util/sparse_vector.h"

namespace meta
{
namespace stats
{

template <class T>
class dirichlet
{
  public:
    dirichlet(double alpha, uint64_t n);

    template <class Iter>
    dirichlet(Iter begin, Iter end);

    dirichlet(const dirichlet& other);

    dirichlet(dirichlet&& other);

    dirichlet& operator=(dirichlet rhs);

    ~dirichlet();

    double pseudo_counts(const T& event) const;

    double pseudo_counts() const;

    void swap(dirichlet& other);

  private:

    enum class type
    {
        SYMMETRIC,
        ASYMMETRIC
    } type_;

    union parameters
    {
        parameters()
        {
           // nothing
        }

        parameters(double alpha)
        {
            fixed_alpha_ = alpha;
        }

        template <class Iter>
        parameters(Iter begin, Iter end)
        {
            new (&sparse_alpha_) util::sparse_vector<T, double>{begin, end};
        }

        ~parameters()
        {
            // nothing
        }

        double fixed_alpha_;
        util::sparse_vector<T, double> sparse_alpha_;
    } params_;

    double alpha_sum_;
};
}
}

#include "stats/dirichlet.tcc"
#endif