標準庫標頭檔案 <coroutine> (C++20)

 

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語言支援 <cfloat> <climits> <compare> (C++20) <contracts> (C++26) <coroutine> (C++20) <csetjmp> <csignal> <cstdarg> <cstddef> <cstdint> (C++11) <cstdlib> <exception> <initializer_list> (C++11)    <limits> <new> <source_location> (C++20) <stdfloat> (C++23) <typeinfo> <version> (C++20) 概念 <concepts> (C++20) 診斷 <cassert> <cerrno> <debugging> (C++26) <stacktrace> (C++23) <stdexcept> <system_error> (C++11) 記憶體管理 <memory> <memory_resource> (C++17) <scoped_allocator> (C++11) 超程式設計 <type_traits> (C++11) <ratio> (C++11)

通用工具 <any> (C++17) <bitset> <bit> (C++20) <charconv> (C++17) <expected> (C++23) <format> (C++20) <functional> <optional> (C++17) <tuple> (C++11) <typeindex> (C++11) <utility> <variant> (C++17) 容器 <array> (C++11) <deque> <flat_map> (C++23) <flat_set> (C++23) <forward_list> (C++11) <hive> (C++26) <inplace_vector> (C++26)    <list> <map> <mdspan> (C++23) <queue> <set> <span> (C++20) <stack> <unordered_map> (C++11) <unordered_set> (C++11) <vector> 迭代器 <iterator> Ranges <generator> (C++23) <ranges> (C++20)

演算法 <algorithm> <numeric> 字串 <cctype> <cstring> <cuchar> (C++11) <cwchar> <cwctype> <string_view> (C++17) <string> 文字處理 <clocale> <codecvt> (C++11/17/26*) <locale> <regex> (C++11) <text_encoding> (C++26)    數值 <cfenv> (C++11) <cmath> <complex> <linalg> (C++26) <numbers> (C++20) <random> (C++11) <simd> (C++26) <valarray> 時間 <chrono> (C++11) <ctime> C 相容性 <ccomplex> (C++11/17/20*) <ciso646> (直到 C++20) <cstdalign> (C++11/17/20*) <cstdbool> (C++11/17/20*) <ctgmath> (C++11/17/20*)

輸入/輸出 <cinttypes> (C++11) <cstdio> <filesystem> (C++17) <fstream> <iomanip> <iosfwd> <iostream> <ios> <istream> <ostream> <print> (C++23) <spanstream> (C++23) <sstream> <streambuf> <strstream> (C++98/26*) <syncstream> (C++20) 併發支援 <atomic> (C++11) <barrier> (C++20) <condition_variable> (C++11) <future> (C++11) <hazard_pointer> (C++26) <latch> (C++20) <mutex> (C++11) <rcu> (C++26) <semaphore> (C++20) <shared_mutex> (C++14) <stdatomic.h> (C++23) <stop_token> (C++20) <thread> (C++11) 執行支援 <execution> (C++17)

 

此標頭檔案是語言支援庫的一部分。

包含
<compare> (C++20)	三路比較運算子支援
類
coroutine_traits (C++20)	用於發現協程 promise 型別的 trait 型別 (類模板)
coroutine_handle (C++20)	用於引用已暫停或正在執行的協程 (類模板)
std::hash<std::coroutine_handle> (C++20)	對 std::coroutine_handle 的雜湊支援 (類模板特化)
無操作協程
noop_coroutine_promise (C++20)	用於沒有可觀察效果的協程 (類)
noop_coroutine_handle (C++20)	std::coroutine_handle<std::noop_coroutine_promise>，旨在引用無操作協程 (型別定義)
平凡可等待物件
suspend_never (C++20)	指示 await 表示式不應暫停 (類)
suspend_always (C++20)	指示 await 表示式應始終暫停 (類)
函式
operator==operator<=> (C++20)	比較兩個 coroutine_handle 物件 (函式)
無操作協程
noop_coroutine (C++20)	建立一個協程控制代碼，當恢復或銷燬時沒有可觀察到的效果 (函式)

概要

#include <compare>
 
namespace std {
  // coroutine traits
  template<class R, class... ArgTypes>
    struct coroutine_traits;
 
  // coroutine handle
  template<class Promise = void>
    struct coroutine_handle;
 
  // comparison operators
  constexpr bool operator==(coroutine_handle<> x, coroutine_handle<> y) noexcept;
  constexpr strong_ordering operator<=>(coroutine_handle<> x, 
                                        coroutine_handle<> y) noexcept;
 
  // hash support
  template<class T> struct hash;
  template<class P> struct hash<coroutine_handle<P>>;
 
  // no-op coroutines
  struct noop_coroutine_promise;
 
  template<> struct coroutine_handle<noop_coroutine_promise>;
  using noop_coroutine_handle = coroutine_handle<noop_coroutine_promise>;
 
  noop_coroutine_handle noop_coroutine() noexcept;
 
  // trivial awaitables
  struct suspend_never;
  struct suspend_always;
}

類模板 std::coroutine_handle

namespace std {
  template<>
  struct coroutine_handle<void>
  {
    // construct/reset
    constexpr coroutine_handle() noexcept;
    constexpr coroutine_handle(nullptr_t) noexcept;
    coroutine_handle& operator=(nullptr_t) noexcept;
 
    // export/import
    constexpr void* address() const noexcept;
    static constexpr coroutine_handle from_address(void* addr);
 
    // observers
    constexpr explicit operator bool() const noexcept;
    bool done() const;
 
    // resumption
    void operator()() const;
    void resume() const;
    void destroy() const;
 
  private:
    void* ptr;  // exposition only
  };
 
  template<class Promise>
  struct coroutine_handle
  {
    // construct/reset
    constexpr coroutine_handle() noexcept;
    constexpr coroutine_handle(nullptr_t) noexcept;
    static coroutine_handle from_promise(Promise&);
    coroutine_handle& operator=(nullptr_t) noexcept;
 
    // export/import
    constexpr void* address() const noexcept;
    static constexpr coroutine_handle from_address(void* addr);
 
    // conversion
    constexpr operator coroutine_handle<>() const noexcept;
 
    // observers
    constexpr explicit operator bool() const noexcept;
    bool done() const;
 
    // resumption
    void operator()() const;
    void resume() const;
    void destroy() const;
 
    // promise access
    Promise& promise() const;
 
  private:
    void* ptr;  // exposition only 
  };
}

類 std::noop_coroutine_promise

namespace std {
  struct noop_coroutine_promise {};
}

類 std::coroutine_handle<std::noop_coroutine_promise>

namespace std {
  template<>
  struct coroutine_handle<noop_coroutine_promise>
  {
    // conversion
    constexpr operator coroutine_handle<>() const noexcept;
 
    // observers
    constexpr explicit operator bool() const noexcept;
    constexpr bool done() const noexcept;
 
    // resumption
    constexpr void operator()() const noexcept;
    constexpr void resume() const noexcept;
    constexpr void destroy() const noexcept;
 
    // promise access
    noop_coroutine_promise& promise() const noexcept;
 
    // address
    constexpr void* address() const noexcept;
  private:
    coroutine_handle(/* unspecified */);
    void* ptr; // exposition only 
  };
}

類 std::suspend_never

namespace std {
  struct suspend_never {
    constexpr bool await_ready() const noexcept { return true; }
    constexpr void await_suspend(coroutine_handle<>) const noexcept {}
    constexpr void await_resume() const noexcept {}
  };
}

類 std::suspend_always

namespace std {
  struct suspend_always {
    constexpr bool await_ready() const noexcept { return false; }
    constexpr void await_suspend(coroutine_handle<>) const noexcept {}
    constexpr void await_resume() const noexcept {}
  };
}