wwa::coro::async_generator< Result > Class Template Reference

An asynchronous generator that produces values of type Result. More...

#include <async_generator.h>

Collaboration diagram for wwa::coro::async_generator< Result >:

Classes
class	iterator
	An input iterator that asynchronously produces values of type Result. More...
class	promise_type
	The promise type of the generator. More...

Public Member Functions
constexpr	async_generator () noexcept=default
	Default constructor.
constexpr	async_generator (async_generator &&other) noexcept
	Move constructor.
	~async_generator ()
	Destructor.
auto	begin () noexcept
	Returns an awaitable iterator to the current item of the generator.
constexpr auto	end () const noexcept
	Returns a sentinel iterator.
async_generator &	operator= (async_generator &&other) noexcept
	Move assignment operator.

Detailed Description

template<typename Result>
class wwa::coro::async_generator< Result >

An asynchronous generator that produces values of type Result.

The generator is a coroutine that produces values of type Result asynchronously. Unlike synchronous counterparts, an asynchronous generator can use co_await in its body. The caller must use co_await on the begin() iterator and its increment operator.

Example:

wwa::coro::async_generator<int> async_first_n(int n)
{
    int v = 0;
    while (v < n) {
        co_yield v;
        // Asynchronous generators can use `co_await`; synchronous ones cannot
        v = co_await get_next_value(v);
    }
}

auto gen = async_first_n(5);
auto it  = co_await gen.begin();  // IMPORTANT! co_await is required
auto end = gen.end();
 
while (it != end) {
    std::cout << *it << "\n";
    co_await ++it;  // IMPORTANT! co_await is required
}

Template Parameters

Result

The type of the values produced by the generator.

Examples

advance_with_begin.cpp, async_generator.cpp, and sync_generator_adapter.cpp.

Definition at line 47 of file async_generator.h.

Constructor & Destructor Documentation

async_generator() [1/2]

template<typename Result>

wwa::coro::async_generator< Result >::async_generator ( )

constexprdefaultnoexcept

Default constructor.

Constructs an empty generator (begin() == end()).

async_generator() [2/2]

template<typename Result>

wwa::coro::async_generator< Result >::async_generator ( async_generator< Result > && other )

inlineconstexprnoexcept

Move constructor.

Constructs a generator by moving the coroutine handle from another generator.

Parameters

other

The other generator to move from.

Definition at line 512 of file async_generator.h.

~async_generator()

template<typename Result>

wwa::coro::async_generator< Result >::~async_generator ( )

inline

Destructor.

Destroys the generator and the coroutine handle.

Definition at line 524 of file async_generator.h.

Member Function Documentation

begin()

template<typename Result>

auto wwa::coro::async_generator< Result >::begin ( )

inlinenodiscardnoexcept

Returns an awaitable iterator to the current item of the generator.

This method returns an awaitable iterator to the current item of the generator. Because generators cannot be restarted, this method can be used to iterate over the generator:

auto gen = async_first_n(5);
auto it  = co_await gen.begin();
auto end = gen.end();
 
do {
    std::cout << *it << " ";
} while (co_await gen.begin() != end);

Attention

The caller must use co_await on the return value of this method.

Returns

Awaitable iterator.

Definition at line 576 of file async_generator.h.

end()

template<typename Result>

auto wwa::coro::async_generator< Result >::end ( ) const

inlinenodiscardconstexprnoexcept

Returns a sentinel iterator.

This method returns a sentinel iterator that marks the end of the generator.

Returns

Sentinel iterator.

Definition at line 592 of file async_generator.h.

operator=()

template<typename Result>

async_generator & wwa::coro::async_generator< Result >::operator= ( async_generator< Result > && other )

inlinenoexcept

Move assignment operator.

Assigns the contents of another generator to this generator by moving them.

Parameters

other

The other generator to move.

Returns

Reference to this generator.

Definition at line 543 of file async_generator.h.

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The documentation for this class was generated from the following file:

• async_generator.h