cpp-dice-roller/include/dice-roll/die.h

//
//  die.hpp
//  dice-roll
//
//  Created by Sam Jaffe on 12/1/18.
//  Copyright © 2018 Sam Jaffe. All rights reserved.
//

#pragma once

#include <iosfwd>
#include <string>
#include <vector>

namespace dice {
enum class sign { PLUS = 1, MINUS = -1, ZERO = 0 };

template <typename T> static sign sgn(T val) {
  return sign((T(0) < val) - (val < T(0)));
}

int sgn(sign);

struct keep {
  enum { All, Highest, Lowest } method;
  int amount;
};

struct die {
  sign sgn;
  int num, sides;
  keep keep{keep::All, 0};
};

struct mod {
  operator int() const;
  sign sign;
  int value;
};

/**
 * In some cases, the roller is not interested in the actual value of the dice
 * rolled, but only if they pass some metric.
 * This object allows us to perform that check, and then conveniently obfuscate
 * the numbers rolled so that the player cannot intuit their odds of success in
 * the short term.
 */
struct difficulty_class {
  enum class test { None, Less, LessOrEqual, Greater, GreaterOrEqual };

  bool operator()(int value) const;

  test comp{test::None};
  int against{0};
};

// Default value: 1{+0}
struct dice {
  int num{1};
  std::vector<die> of{};
  std::vector<mod> modifier{+0};
  difficulty_class dc{};
};

/**
 * @brief A generator function to turn a string representation of a dice roll
 * into a C++ object
 * @param strdice A string representation of a dice roll, represented as one of
 * the following expression classes: Die = [1-9]?\d*d[1-9]\d* SingleRoll:
 * ($Die|\d+)((+|-)($Die|\d+))* RepeatRoll: [1-9]\d*\{$SingleRoll\}
 * @return a dice object representing the roll
 * @throws dice::unexpected_token if a parse failure occurs
 */
dice from_string(std::string const & strdice);

std::ostream & operator<<(std::ostream & out, sign s);
std::ostream & operator<<(std::ostream & out, dice const & d);
std::istream & operator>>(std::istream & out, dice & d);
}