cpp-mathematic-limit/include/math/limit.h

//
//  limit.h
//  utilities
//
//  Created by Sam Jaffe on 10/22/13.
//  Copyright (c) 2013 Sam Jaffe. All rights reserved.
//

#pragma once

#include <stdexcept>

#include <math/clamp.h>

namespace math {

struct {
} assert_bounds;
using AssertBounds = decltype(assert_bounds);

template <typename T, T MINIMUM_VALUE, T MAXIMUM_VALUE> class Bound final {
public:
  static_assert(MINIMUM_VALUE <= MAXIMUM_VALUE,
                "The minimum value must be less than or equal to the maximum");

  using value_type = T;
  using underlying_type = value_type;

  static constexpr const value_type min = MINIMUM_VALUE;
  static constexpr const value_type max = MAXIMUM_VALUE;

private:
  value_type value{min};

public:
  constexpr Bound() = default;
  constexpr Bound(value_type const & val) noexcept
      : value(clamp(val, min, max)) {}

  Bound(AssertBounds, value_type val) : value(val) {
    if (val < min || max < val) {
      throw std::out_of_range{"Must construct a value within range"};
    }
  }

  Bound & operator-=(value_type by) { return *this = Bound(value - by); }
  Bound & operator+=(value_type by) { return *this = Bound(value + by); }
  Bound operator+(value_type by) const { return Bound{*this} += by; }
  Bound operator-(value_type by) const { return Bound{*this} -= by; }
  Bound & operator--() { return *this -= 1; }
  Bound & operator++() { return *this += 1; }

  Bound operator--(int) {
    Bound tmp = *this;
    operator--();
    return tmp;
  }

  Bound operator++(int) {
    Bound tmp = *this;
    operator++();
    return tmp;
  }

  operator value_type() const { return value; }
};

template <typename T, T MINMAX> using SymBound = Bound<T, -MINMAX, +MINMAX>;
template <typename T, T VAL>
using UniBound =
    std::conditional_t<0 <= VAL, Bound<T, 0, VAL>, Bound<T, VAL, 0>>;

template <typename L, L l1, L h1, typename R, R l2, R h2>
auto operator+(Bound<L, l1, h1> lhs, Bound<R, l2, h2> rhs) {
  return L(lhs) + R(rhs);
}

template <typename L, L l1, L h1, typename R, R l2, R h2>
auto operator-(Bound<L, l1, h1> lhs, Bound<R, l2, h2> rhs) {
  return L(lhs) - R(rhs);
}

template <typename L, L l1, L h1, typename R, R l2, R h2>
auto operator*(Bound<L, l1, h1> lhs, Bound<R, l2, h2> rhs) {
  return L(lhs) * R(rhs);
}

template <typename L, L l1, L h1, typename R, R l2, R h2>
auto operator/(Bound<L, l1, h1> lhs, Bound<R, l2, h2> rhs) {
  return L(lhs) / R(rhs);
}
}