Number with infinity
(Mylib/Math/unbounded.cpp)

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• Last update: 2021-04-23 23:44:44+09:00
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Operations

Requirements

Notes

Problems

References

Required by

• Bellman-Ford algorithm (Mylib/Graph/ShortestPath/bellman_ford.cpp)

Verified with

• test/aoj/GRL_1_B/main.test.cpp

Code

#pragma once
#include <iostream>

template <typename T>
struct unbounded {
private:
  enum class tag_t { POSITIVE_INFINITY,
                     NEGATIVE_INFINITY,
                     FINITE } tag_;
  T value_;

  unbounded(tag_t tag_) : tag_(tag_) {}

public:
  using value_type = T;

  unbounded() : tag_(tag_t::FINITE), value_(T()) {}
  unbounded(T value_) : tag_(tag_t::FINITE), value_(value_) {}
  unbounded(const unbounded<T>& that) : tag_(that.tag_), value_(that.value_) {}

  bool is_positive_inf() const { return tag_ == tag_t::POSITIVE_INFINITY; }
  bool is_negative_inf() const { return tag_ == tag_t::NEGATIVE_INFINITY; }
  bool is_finite() const { return tag_ == tag_t::FINITE; }

  T value() const { return value_; }
  T& value() { return value_; }

  static auto positive_inf() {
    return unbounded(tag_t::POSITIVE_INFINITY);
  }

  static auto negative_inf() {
    return unbounded(tag_t::NEGATIVE_INFINITY);
  }

  friend std::ostream& operator<<(std::ostream& s, const unbounded& a) {
    switch (a.tag_) {
      case tag_t::POSITIVE_INFINITY: s << "∞"; break;
      case tag_t::NEGATIVE_INFINITY: s << "-∞"; break;
      case tag_t::FINITE: s << a.value_;
    }
    return s;
  }

  unbounded operator-() const {
    if (is_finite())
      return -value_;
    else if (is_positive_inf())
      return unbounded::negative_inf();
    return unbounded::positive_inf();
  }

  auto& operator+=(unbounded that) {
    if (is_finite()) {
      if (that.is_finite())
        value_ += that.value_;
      else
        tag_ = that.tag_;
    }
    return *this;
  }

  auto operator+(unbounded that) const {
    return unbounded(*this) += that;
  }

  auto& operator-=(unbounded that) {
    return (*this) += (-that);
  }

  auto operator-(unbounded that) const {
    return unbounded(*this) -= that;
  }

  int compare(unbounded that) const {
    if (is_positive_inf()) {
      if (that.is_positive_inf())
        return 0;
      else
        return 1;
    } else if (is_negative_inf()) {
      if (that.is_negative_inf())
        return 0;
      else
        return -1;
    } else {
      if (that.is_positive_inf())
        return -1;
      else if (that.is_negative_inf())
        return 1;
      else
        return (value_ > that.value_) - (value_ < that.value_);
    }
  }

  bool operator==(unbounded that) const { return compare(that) == 0; }
  bool operator!=(unbounded that) const { return compare(that) != 0; }
  bool operator<(unbounded that) const { return compare(that) < 0; }
  bool operator<=(unbounded that) const { return compare(that) <= 0; }
  bool operator>(unbounded that) const { return compare(that) > 0; }
  bool operator>=(unbounded that) const { return compare(that) >= 0; }
};

#line 2 "Mylib/Math/unbounded.cpp"
#include <iostream>

template <typename T>
struct unbounded {
private:
  enum class tag_t { POSITIVE_INFINITY,
                     NEGATIVE_INFINITY,
                     FINITE } tag_;
  T value_;

  unbounded(tag_t tag_) : tag_(tag_) {}

public:
  using value_type = T;

  unbounded() : tag_(tag_t::FINITE), value_(T()) {}
  unbounded(T value_) : tag_(tag_t::FINITE), value_(value_) {}
  unbounded(const unbounded<T>& that) : tag_(that.tag_), value_(that.value_) {}

  bool is_positive_inf() const { return tag_ == tag_t::POSITIVE_INFINITY; }
  bool is_negative_inf() const { return tag_ == tag_t::NEGATIVE_INFINITY; }
  bool is_finite() const { return tag_ == tag_t::FINITE; }

  T value() const { return value_; }
  T& value() { return value_; }

  static auto positive_inf() {
    return unbounded(tag_t::POSITIVE_INFINITY);
  }

  static auto negative_inf() {
    return unbounded(tag_t::NEGATIVE_INFINITY);
  }

  friend std::ostream& operator<<(std::ostream& s, const unbounded& a) {
    switch (a.tag_) {
      case tag_t::POSITIVE_INFINITY: s << "∞"; break;
      case tag_t::NEGATIVE_INFINITY: s << "-∞"; break;
      case tag_t::FINITE: s << a.value_;
    }
    return s;
  }

  unbounded operator-() const {
    if (is_finite())
      return -value_;
    else if (is_positive_inf())
      return unbounded::negative_inf();
    return unbounded::positive_inf();
  }

  auto& operator+=(unbounded that) {
    if (is_finite()) {
      if (that.is_finite())
        value_ += that.value_;
      else
        tag_ = that.tag_;
    }
    return *this;
  }

  auto operator+(unbounded that) const {
    return unbounded(*this) += that;
  }

  auto& operator-=(unbounded that) {
    return (*this) += (-that);
  }

  auto operator-(unbounded that) const {
    return unbounded(*this) -= that;
  }

  int compare(unbounded that) const {
    if (is_positive_inf()) {
      if (that.is_positive_inf())
        return 0;
      else
        return 1;
    } else if (is_negative_inf()) {
      if (that.is_negative_inf())
        return 0;
      else
        return -1;
    } else {
      if (that.is_positive_inf())
        return -1;
      else if (that.is_negative_inf())
        return 1;
      else
        return (value_ > that.value_) - (value_ < that.value_);
    }
  }

  bool operator==(unbounded that) const { return compare(that) == 0; }
  bool operator!=(unbounded that) const { return compare(that) != 0; }
  bool operator<(unbounded that) const { return compare(that) < 0; }
  bool operator<=(unbounded that) const { return compare(that) <= 0; }
  bool operator>(unbounded that) const { return compare(that) > 0; }
  bool operator>=(unbounded that) const { return compare(that) >= 0; }
};

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