cmp.hpp

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//
// Created by YongGyu Lee on 5/8/24.
//
 
#ifndef VCCC_UTILITY_CMP_HPP_
#define VCCC_UTILITY_CMP_HPP_
 
#include <type_traits>
 
#include "vccc/__type_traits/conjunction.hpp"
#include "vccc/__type_traits/is_character.hpp"
#include "vccc/__type_traits/negation.hpp"
#include "vccc/__type_traits/remove_cvref.hpp"
 
namespace vccc {
namespace detail {
 
template<typename T, typename U, typename... SameSignity>
constexpr bool cmp_equal_impl(T t, U u, SameSignity...) noexcept {
  return t == u;
}
 
template<typename T, typename U>
constexpr bool cmp_equal_impl(T t, U u, std::true_type, std::false_type) noexcept {
  return t >= 0 && std::make_unsigned_t<T>(t) == u;
}
 
template<typename T, typename U>
constexpr bool cmp_equal_impl(T t, U u, std::false_type, std::true_type) noexcept {
  return u >= 0 && std::make_unsigned_t<U>(u) == t;
}
 
template<typename T, typename U, typename... SameSignity>
constexpr bool cmp_less_impl(T t, U u, SameSignity...) noexcept {
  return t < u;
}
 
template<typename T, typename U>
constexpr bool cmp_less_impl(T t, U u, std::true_type, std::false_type) noexcept {
  return t < 0 || std::make_unsigned_t<T>(t) < u;
}
 
template<typename T, typename U>
constexpr bool cmp_less_impl(T t, U u, std::false_type, std::true_type) noexcept {
  return u >= 0 && t < std::make_unsigned_t<U>(u);
}
 
template<typename T>
using cmp_requires_one =
    conjunction<
        std::is_integral<T>,
        negation<is_character<T>>,
        negation<std::is_same<T, bool>>
    >;
template<typename T, typename U>
using cmp_requires = conjunction<cmp_requires_one<remove_cvref_t<T>>, cmp_requires_one<remove_cvref_t<U>>>;
 
} // namespace detail
 
 
template<typename T, typename U>
constexpr bool cmp_equal(T t, U u) noexcept {
  static_assert(detail::cmp_requires<T, U>::value, "Both values must be integral, not a character type and not bool");
  return vccc::detail::cmp_equal_impl(t, u, std::is_signed<T>{}, std::is_signed<U>{});
}
 
template<typename T, typename U>
constexpr bool cmp_not_equal(T t, U u) noexcept {
  return !vccc::cmp_equal(t, u);
}
 
template<typename T, typename U>
constexpr bool cmp_less(T t, U u) noexcept {
  static_assert(detail::cmp_requires<T, U>::value, "Both values must be integral, not a character type and not bool");
  return vccc::detail::cmp_less_impl(t, u, std::is_signed<T>{}, std::is_signed<U>{});
}
 
template<typename T, typename U>
constexpr bool cmp_greater(T t, U u) noexcept {
  return vccc::cmp_less(u, t);
}
 
template<class T, class U>
constexpr bool cmp_less_equal(T t, U u) noexcept {
  return !vccc::cmp_less(u, t);
}
 
template<class T, class U>
constexpr bool cmp_greater_equal(T t, U u) noexcept {
  return !vccc::cmp_less(t, u);
}
 
 
} // namespace vccc
 
#endif // VCCC_UTILITY_CMP_HPP_