min を得る演算のモノイド (utility/monoid/min.cpp)

#ifndef H_min_monoid
#define H_min_monoid

/**
 * @brief min を得る演算のモノイド
 * @author えびちゃん
 */

#include <algorithm>
#include <utility>

#include "utility/limits.cpp"

template <typename Tp>
class min_monoid {
public:
  using value_type = Tp;

private:
  value_type M_x = limits<Tp>::max();

public:
  min_monoid() = default;  // identity

  min_monoid(value_type const& x): M_x(x) {}

  min_monoid& operator +=(min_monoid const& that) {
    M_x = std::min(M_x, that.M_x);
    return *this;
  }
  friend bool operator ==(min_monoid const& lhs, min_monoid const& rhs) {
    return lhs.M_x == rhs.M_x;
  }

  friend min_monoid operator +(min_monoid lhs, min_monoid const& rhs) {
    return lhs += rhs;
  }
  friend bool operator !=(min_monoid const& lhs, min_monoid const& rhs) {
    return !(lhs == rhs);
  }

  value_type const& get() const { return M_x; }
};

#endif  /* !defined(H_min_monoid) */

#line 1 "utility/monoid/min.cpp"



/**
 * @brief min を得る演算のモノイド
 * @author えびちゃん
 */

#include <algorithm>
#include <utility>

#line 1 "utility/limits.cpp"



/**
 * @brief 型依存の定数
 * @author えびちゃん
 */

#include <limits>
#line 11 "utility/limits.cpp"

template <typename Tp>
class limits: public std::numeric_limits<Tp> {};

template <typename T1, typename T2>
class limits<std::pair<T1, T2>> {
public:
  static constexpr auto min() {
    return std::make_pair(limits<T1>::min(), limits<T2>::min());
  }
  static constexpr auto max() {
    return std::make_pair(limits<T1>::max(), limits<T2>::max());
  }
};


#line 13 "utility/monoid/min.cpp"

template <typename Tp>
class min_monoid {
public:
  using value_type = Tp;

private:
  value_type M_x = limits<Tp>::max();

public:
  min_monoid() = default;  // identity

  min_monoid(value_type const& x): M_x(x) {}

  min_monoid& operator +=(min_monoid const& that) {
    M_x = std::min(M_x, that.M_x);
    return *this;
  }
  friend bool operator ==(min_monoid const& lhs, min_monoid const& rhs) {
    return lhs.M_x == rhs.M_x;
  }

  friend min_monoid operator +(min_monoid lhs, min_monoid const& rhs) {
    return lhs += rhs;
  }
  friend bool operator !=(min_monoid const& lhs, min_monoid const& rhs) {
    return !(lhs == rhs);
  }

  value_type const& get() const { return M_x; }
};