cpp-shared-random-generator/include/random/tape.h

//
//  tape.hpp
//  shared_random_generator
//
//  Created by Sam Jaffe on 3/19/23.
//  Copyright © 2023 Sam Jaffe. All rights reserved.
//

#pragma once

#include <string>
#include <tuple>
#include <variant>
#include <vector>

#include <random/device.h>

namespace engine::random {
class Tape : public Device {
public:
  // Allow for the serialization and de-serialization of this Tape
  using serial_type =
      std::vector<std::tuple<bool, std::string, double, double, double>>;

private:
  enum class Type : char;
  template <typename T> struct EntryT {
    EntryT(T min, T max) : min(min), max(max), result() {}
    EntryT(T min, T max, T result) : min(min), max(max), result(result) {}

    T min;
    T max;
    T result;
  };
  
  struct Entry {
    template <typename T>
    Entry(Type type, EntryT<T> params) : type(type), params(params) {}

    Type type;
    std::variant<EntryT<double>, EntryT<unsigned int>> params;
  };

private:
  size_t index_{0}; // transient
  std::vector<Entry> entries_;

public:
  Tape() = default;
  Tape(serial_type serial);
  explicit operator serial_type() const;

  unsigned int exclusive(unsigned int max) override;
  double exclusive(double min, double max) override;
  double inclusive(double min, double max) override;

  void exclusive(unsigned int max, unsigned int result);
  void exclusive(double min, double max, double result);
  void inclusive(double min, double max, double result);

private:
  template <typename T> T fetch(Type type, T min, T max);
};
}