memoryless.hpp

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#ifndef SSMPACK_PROCESS_MEMORYLESS_HPP
#define SSMPACK_PROCESS_MEMORYLESS_HPP

#include "ssmkit/distribution/conditional.hpp"
#include "ssmkit/process/base_process.hpp"

#include <algorithm>
#include <cmath>
#include <type_traits>
#include <vector>

namespace ssmkit {
namespace process {

template <typename TPDF, typename TParamMap>
class Memoryless : public BaseProcess<Memoryless<TPDF, TParamMap>> {
 private:
  distribution::Conditional<TPDF, TParamMap> cpdf_;

 public:
  
  Memoryless(distribution::Conditional<TPDF, TParamMap> cpdf)
      : cpdf_(std::move(cpdf)) {}
  
  
  auto initialize() -> decltype(std::declval<TPDF>().random()) {
    /* memoryless doesn't have sensible initialization so initialize simply
     * returns the default value of the random variable type.
     */
    decltype(std::declval<TPDF>().random()) rv;
    return rv;
  }

  template <typename... Args>
  auto random(const Args &... args) -> decltype(std::declval<TPDF>().random()) {
    return cpdf_.random(args...);
  }

  template <typename... Args>
  double likelihood(const decltype(std::declval<TPDF>().random()) &rv,
                    const Args &... args) {
    return cpdf_.likelihood(rv, args...);
  }

  distribution::Conditional<TPDF, TParamMap> & 
  getCPDF() {return cpdf_;}
};

template <typename TPDF, typename TParamMap>
Memoryless<TPDF, TParamMap>
makeMemoryless(distribution::Conditional<TPDF, TParamMap> cpdf) {
  return Memoryless<TPDF, TParamMap>(cpdf);
}

} // namespace process
} // namespace ssmkit

#endif // SSMPACK_PROCESS_MEMORYLESS_HPP