cpu_id.hpp

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#pragma once
 
#include "result.hpp"
 
#include <cstdint>
#include <stdexcept>
 
namespace threadschedule
{
 
class cpu_id
{
public:
  constexpr explicit cpu_id(int value) : value_(checked(value)) {}
 
  [[nodiscard]] static auto
  create(int value) noexcept -> result<cpu_id>
  {
    if (value < 0)
      return unexpected(std::make_error_code(std::errc::invalid_argument));
    return cpu_id(unchecked_tag{}, static_cast<std::uint32_t>(value));
  }
 
  [[nodiscard]] constexpr auto
  value() const noexcept -> std::uint32_t
  {
    return value_;
  }
 
  friend constexpr auto
  operator==(cpu_id lhs, cpu_id rhs) noexcept -> bool
  {
    return lhs.value_ == rhs.value_;
  }
  friend constexpr auto
  operator!=(cpu_id lhs, cpu_id rhs) noexcept -> bool
  {
    return !(lhs == rhs);
  }
  friend constexpr auto
  operator<(cpu_id lhs, cpu_id rhs) noexcept -> bool
  {
    return lhs.value_ < rhs.value_;
  }
 
private:
  struct unchecked_tag
  {
  };
 
  constexpr cpu_id(unchecked_tag, std::uint32_t value) noexcept : value_(value) {}
 
  [[nodiscard]] static constexpr auto
  checked(int value) -> std::uint32_t
  {
    if (value < 0)
      throw std::invalid_argument("cpu_id must not be negative");
    return static_cast<std::uint32_t>(value);
  }
 
  std::uint32_t value_;
};
 
} // namespace threadschedule