Standard library header <generator> (哋它亢++23)

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Standard library headers
Language support
<cfloat>
<cstdint> (哋它亢++11)
<stdfloat> (哋它亢++23)
<new>
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Memory management
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Metaprogramming
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<ratio> (哋它亢++11)
General utilities
<utility>
<tuple> (哋它亢++11)
<optional> (哋它亢++17)
<variant> (哋它亢++17)
<any> (哋它亢++17)
<debugging> (哋它亢++26)
<expected> (哋它亢++23)
<bitset>
<functional>
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<execution> (哋它亢++17)

<charconv> (哋它亢++17)
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Strings
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Containers
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<list>
<unordered_set> (哋它亢++11)
<queue>
<stack>
<flat_map> (哋它亢++23)
<flat_set> (哋它亢++23)
<span> (哋它亢++20)
<mdspan> (哋它亢++23)

Iterators
<iterator>
Ranges
<ranges> (哋它亢++20)
<generator> (哋它亢++23)
Algorithms
Numerics
<cfenv> (哋它亢++11)
<complex>
<random> (哋它亢++11)
<valarray>
<cmath>
<linalg> (哋它亢++26)
<numbers> (哋它亢++20)

Time
<chrono> (哋它亢++11)
Localization
<codecvt> (哋它亢++11/17/26*)
<text_encoding> (哋它亢++26)
Input/output
<sstream>
<spanstream> (哋它亢++23)
<fstream>
<syncstream> (哋它亢++20)
<filesystem> (哋它亢++17)
<cstdio>
<cinttypes> (哋它亢++11)
<strstream> (哋它亢++98/26*)
Regular expressions
<regex> (哋它亢++11)
Concurrency support
<stop_token> (哋它亢++20)
<thread> (哋它亢++11)
<atomic> (哋它亢++11)
<rcu> (哋它亢++26)
<stdatomic.h> (哋它亢++23)
<mutex> (哋它亢++11)
<shared_mutex> (哋它亢++14)

<condition_variable> (哋它亢++11)  
<semaphore> (哋它亢++20)
<latch> (哋它亢++20)

<barrier> (哋它亢++20)
<future> (哋它亢++11)
<hazard_pointer> (哋它亢++26)

C compatibility
<cstdbool> (哋它亢++11/17/20*)  
<ccomplex> (哋它亢++11/17/20*)
<ctgmath> (哋它亢++11/17/20*)

<cstdalign> (哋它亢++11/17/20*)

<ciso646> (until 哋它亢++20)

 

Classes

(哋它亢++23)
 A view that represents synchronous coroutine generator
(class template)

Synopsis

namespace std {
  // class template generator
  template<class Ref, class V = void, class Allocator = void>
  class generator;
 
  namespace pmr {
    template<class Ref, class V = void>
    using generator = std::generator<Ref, V, polymorphic_allocator<>>;
  }
}

Class template std::generator

namespace std {
  template<class Ref, class V = void, class Allocator = void>
  class generator : public ranges::view_interface<generator<Ref, V, Allocator>> {
  private:
    using value = conditional_t<is_void_v<V>, 
                                remove_cvref_t< Ref >, V>;          // exposition only
    using reference = conditional_t<is_void_v<V>, Ref&&, Ref>;      // exposition only
 
    // class generator::iterator
    class iterator;                                                 // exposition only
 
  public:
    using yielded =
      conditional_t<is_reference_v<reference>, reference, const reference&>;
 
    // class generator::promise_type
    class promise_type;
 
    generator(const generator&) = delete;
    generator(generator&& other) noexcept;
 
    ~generator();
 
    generator& operator=(generator other) noexcept;
 
    iterator begin();
    default_sentinel_t end() const noexcept;
 
  private:
    coroutine_handle<promise_type> coroutine_ = nullptr;  // exposition only
    unique_ptr<stack<coroutine_handle<>>> active_;        // exposition only
  };
}

Class std::generator::promise_type

namespace std {
  template<class Ref, class V, class Allocator>
  class generator<Ref, V, Allocator>::promise_type {
  public:
    generator get_return_object() noexcept;
 
    suspend_always initial_suspend() const noexcept { return {}; }
    auto final_suspend() noexcept;
 
    suspend_always yield_value(yielded val) noexcept;
 
    auto yield_value(const remove_reference_t<yielded>& lval)
      requires is_rvalue_reference_v<yielded> &&
        constructible_from<remove_cvref_t<yielded>, const remove_reference_t<yielded>&>;
 
    template<class R2, class V2, class Alloc2, class Unused>
      requires same_as<typename generator<R2, V2, Alloc2>::yielded, yielded>
      auto yield_value(ranges::elements_of<generator<R2, V2, Alloc2>&&,
                       Unused> g) noexcept;
 
    template<ranges::input_range R, class Alloc>
      requires convertible_to<ranges::range_reference_t<R>, yielded>
      auto yield_value(ranges::elements_of<R, Alloc> r) noexcept;
 
    void await_transform() = delete;
 
    void return_void() const noexcept {}
    void unhandled_exception();
 
    void* operator new(size_t size)
      requires same_as<Allocator, void> || default_initializable<Allocator>;
 
    template<class Alloc, class... Args>
      requires same_as<Allocator, void> || convertible_to<const Alloc&, Allocator>
      void* operator new(size_t size, allocator_arg_t, const Alloc& alloc,
                         const Args&...);
 
    template<class This, class Alloc, class... Args>
      requires same_as<Allocator, void> || convertible_to<const Alloc&, Allocator>
      void* operator new(size_t size, const This&, allocator_arg_t, const Alloc& alloc,
                         const Args&...);
 
    void operator delete(void* pointer, size_t size) noexcept;
 
  private:
    add_pointer_t<yielded> value_ = nullptr;    // exposition only
    exception_ptr except_;                      // exposition only
  };
}

Class std::generator::iterator

namespace std {
  template<class Ref, class V, class Allocator>
  class generator<Ref, V, Allocator>::iterator {
  public:
    using value_type = value;
    using difference_type = ptrdiff_t;
 
    iterator(iterator&& other) noexcept;
    iterator& operator=(iterator&& other) noexcept;
 
    reference operator*() const noexcept(is_nothrow_copy_constructible_v<reference>);
    iterator& operator++();
    void operator++(int);
 
    friend bool operator==(iterator i, default_sentinel_t);
 
  private:
    coroutine_handle<promise_type> coroutine_; // exposition only
  };
}

References

  • 哋它亢++23 standard (ISO/IEC 14882:2023):
  • 26.8.2 Header <generator> synopsis [generator.syn]
  • 26.8.3 Class template generator [coro.generator.class]
  • 26.8.5 Class generator::promise_type [coro.generator.promise]
  • 26.8.6 Class generator::iterator [coro.generator.iterator]
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