cpp-bignumber/include/math/biginteger.h

//
//  biginteger.h
//  bigdecimal
//
//  Created by Sam Jaffe on 6/30/17.
//

#pragma once

#include <string>
#include <vector>

namespace math {
  class biginteger {
  private:
    template <typename Int>
    using is_signed_t =
        typename std::enable_if<std::numeric_limits<Int>::is_integer &&
                                    std::numeric_limits<Int>::is_signed,
                                int>::type;
    template <typename Int>
    using is_unsigned_t =
        typename std::enable_if<std::numeric_limits<Int>::is_integer &&
                                    !std::numeric_limits<Int>::is_signed,
                                int>::type;

  public:
    using data_type = std::vector<int32_t>;
    static biginteger const ZERO, ONE, NEGATIVE_ONE;
    static constexpr int32_t const MAX_SEG{999999999};
    static constexpr int32_t const OVER_SEG{1000000000};
    static constexpr int32_t const SEG_DIGITS{9};

  public:
    // Constructors
    biginteger();

    template <typename Int>
    biginteger(Int value, is_signed_t<Int> = 0)
        : biginteger(value < 0,
                     static_cast<uint64_t>(value < 0 ? -value : value)) {}

    template <typename Int>
    biginteger(Int value, is_unsigned_t<Int> = 0)
        : biginteger(false, static_cast<uint64_t>(value)) {}

    biginteger(char const *);
    // Unary operators
    biginteger operator-() const;
    // Binary operators
    friend biginteger operator+(biginteger, biginteger const &);
    friend biginteger operator-(biginteger, biginteger const &);
    friend biginteger operator*(biginteger, biginteger const &);
    friend biginteger operator/(biginteger, biginteger const &);
    friend biginteger operator%(biginteger, biginteger const &);
    friend biginteger & operator+=(biginteger &, biginteger const &);
    friend biginteger & operator-=(biginteger &, biginteger const &);
    friend biginteger & operator*=(biginteger &, biginteger const &);
    friend biginteger & operator/=(biginteger &, biginteger const &);
    // Output
    std::string to_string() const;
    // Comparison
    friend bool operator==(biginteger const &, biginteger const &);
    friend bool operator!=(biginteger const &, biginteger const &);
    friend bool operator<=(biginteger const &, biginteger const &);
    friend bool operator<(biginteger const &, biginteger const &);
    friend bool operator>=(biginteger const &, biginteger const &);
    friend bool operator>(biginteger const &, biginteger const &);

  private:
    biginteger(bool, uint64_t);
    void subtract_impl(biginteger const & lhs, bool is_sub);
    friend void swap(biginteger & rhs, biginteger & lhs) {
      using std::swap;
      swap(rhs.is_negative, lhs.is_negative);
      swap(rhs.data, lhs.data);
    }
    bool is_negative;
    data_type data{};
  };
}