26 Ranges library [ranges]

26.8 Range generators [coro.generator]

26.8.3 Class template generator [coro.generator.class]

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 // [coro.generator.iterator], class generator::iterator class iterator; // exposition only public: using yielded = conditional_t<is_reference_v<reference>, reference, const reference&>; // [coro.generator.promise], 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 }; }

Mandates:

(1.1)
If Allocator is not void, allocator_traits<Allocator>::pointer is a pointer type.
(1.2)
value is a cv-unqualified object type.
(1.3)
reference is either a reference type, or a cv-unqualified object type that models copy_constructible .
(1.4)
Let RRef denote remove_reference_t<reference>&& if reference is a reference type, and reference otherwise.
Each of:
- (1.4.1)
  common_reference_with<reference&&, value&>,
- (1.4.2)
  common_reference_with<reference&&, RRef&&>, and
- (1.4.3)
  common_reference_with<RRef&&, const value&>
is modeled.
[Note 1:
These requirements ensure the exposition-only iterator type can model indirectly_readable and thus input_iterator .
— end note]

If Allocator is not void, it shall meet the Cpp17Allocator requirements.

Specializations of generator model view and input_range .

The behavior of a program that adds a specialization for generator is undefined.