#include <compare>
 
namespace std {
  class thread;
 
  void swap(thread& x, thread& y) noexcept;
 
  // class jthread
  class jthread;
 
  namespace this_thread {
    thread::id get_id() noexcept;
 
    void yield() noexcept;
    template<class Clock, class Duration>
      void sleep_until(const chrono::time_point<Clock, Duration>& abs_time);
    template<class Rep, class Period>
      void sleep_for(const chrono::duration<Rep, Period>& rel_time);
  }
}

namespace std {
  class thread {
  public:
    // types
    class id;
    using native_handle_type = /* implementation-defined */;
 
    // construct/copy/destroy
    thread() noexcept;
    template<class F, class... Args> explicit thread(F&& f, Args&&... args);
    ~thread();
    thread(const thread&) = delete;
    thread(thread&&) noexcept;
    thread& operator=(const thread&) = delete;
    thread& operator=(thread&&) noexcept;
 
    // members
    void swap(thread&) noexcept;
    bool joinable() const noexcept;
    void join();
    void detach();
    id get_id() const noexcept;
    native_handle_type native_handle();
 
    // static members
    static unsigned int hardware_concurrency() noexcept;
  };
}

namespace std {
  class jthread {
  public:
    // types
    using id = thread::id;
    using native_handle_type = thread::native_handle_type;
 
    // constructors, move, and assignment
    jthread() noexcept;
    template<class F, class... Args> explicit jthread(F&& f, Args&&... args);
    ~jthread();
    jthread(const jthread&) = delete;
    jthread(jthread&&) noexcept;
    jthread& operator=(const jthread&) = delete;
    jthread& operator=(jthread&&) noexcept;
 
    // members
    void swap(jthread&) noexcept;
    [[nodiscard]] bool joinable() const noexcept;
    void join();
    void detach();
    [[nodiscard]] id get_id() const noexcept;
    [[nodiscard]] native_handle_type native_handle();
 
    // stop token handling
    [[nodiscard]] stop_source get_stop_source() noexcept;
    [[nodiscard]] stop_token get_stop_token() const noexcept;
    bool request_stop() noexcept;
 
    // specialized algorithms
    friend void swap(jthread& lhs, jthread& rhs) noexcept;
 
    // static members
    [[nodiscard]] static unsigned int hardware_concurrency() noexcept;
 
  private:
    stop_source ssource;        // exposition only
  };
}

namespace std {
  class thread::id {
  public:
    id() noexcept;
  };
 
  bool operator==(thread::id x, thread::id y) noexcept;
  strong_ordering operator<=>(thread::id x, thread::id y) noexcept;
 
  template<class CharT, class Traits>
    basic_ostream<CharT, Traits>&
      operator<<(basic_ostream<CharT, Traits>& out, thread::id id);
 
  // hash support
  template<class T> struct hash;
  template<> struct hash<thread::id>;
}