dpp::awaitable< T > Class Template Reference

Generic awaitable class, represents a future value that can be co_await-ed on. More...

Inheritance diagram for dpp::awaitable< T >:

Collaboration diagram for dpp::awaitable< T >:

Classes
struct	awaiter
	Awaiter returned by co_await. More...

Public Member Functions
	awaitable ()=default
	Construct an empty awaitable. More...
	awaitable (const awaitable &)=delete
	Copy construction is disabled. More...
	awaitable (awaitable &&rhs) noexcept
	Move from another awaitable. More...
	~awaitable ()
	Destructor. More...
awaitable &	operator= (const awaitable &)=delete
	Copy assignment is disabled. More...
awaitable &	operator= (awaitable &&rhs) noexcept
	Move from another awaitable. More...
bool	valid () const noexcept
	Check whether this awaitable refers to a valid promise. More...
bool	await_ready () const
	Check whether or not co_await-ing this would suspend the caller, i.e. if we have the result or not. More...
template<typename Derived >
	requires (std::is_base_of_v< awaitable, std::remove_cv_t< Derived >>) friend awaiter< Derived & > operator co_await(Derived &obj) noexcept
	Overload of the co_await operator. More...
template<typename Derived >
	requires (std::is_base_of_v< awaitable, std::remove_cv_t< Derived >>) friend awaiter< Derived && > operator co_await(Derived &&obj) noexcept
	Overload of the co_await operator. Returns an awaiter referencing this awaitable. More...

Protected Types
using	shared_state = detail::promise::promise_base< T >
using	state_flags = detail::promise::state_flags
using	result_type = T
	The type of the result produced by this task. More...

Protected Member Functions
	awaitable (shared_state *promise) noexcept
	Construct from a promise. More...
uint8_t	abandon ()
	Abandons the promise. More...

Protected Attributes
shared_state *	state_ptr = nullptr
	Non-owning pointer to the promise, which must be kept alive for the entire lifetime of the awaitable. More...

Friends
class	detail::promise::promise_base< T >

Detailed Description

template<typename T>
class dpp::awaitable< T >

Generic awaitable class, represents a future value that can be co_await-ed on.

Roughly equivalent of std::future for coroutines, with the crucial distinction that the future does not own a reference to a "shared state". It holds a non-owning reference to the promise, which must be kept alive for the entire lifetime of the awaitable.

Template Parameters

T	Type of the asynchronous value

See also

promise

Member Typedef Documentation

result_type

template<typename T >

using dpp::awaitable< T >::result_type = T

protected

The type of the result produced by this task.

shared_state

template<typename T >

using dpp::awaitable< T >::shared_state = detail::promise::promise_base<T>

protected

state_flags

template<typename T >

using dpp::awaitable< T >::state_flags = detail::promise::state_flags

protected

Constructor & Destructor Documentation

awaitable() [1/4]

template<typename T >

dpp::awaitable< T >::awaitable ( shared_state *  promise )

inlineprotectednoexcept

Construct from a promise.

Parameters

promise

The promise to refer to.

awaitable() [2/4]

template<typename T >

dpp::awaitable< T >::awaitable ( )

default

Construct an empty awaitable.

Such an awaitable must be assigned a promise before it can be awaited.

awaitable() [3/4]

template<typename T >

dpp::awaitable< T >::awaitable ( const awaitable< T > &  )

delete

Copy construction is disabled.

awaitable() [4/4]

template<typename T >

dpp::awaitable< T >::awaitable ( awaitable< T > &&  rhs )

inlinenoexcept

Move from another awaitable.

Parameters

rhs	The awaitable to move from, left in an unspecified state after this.

~awaitable()

template<typename T >

dpp::awaitable< T >::~awaitable

Destructor.

May signal to the promise that it was destroyed.

Member Function Documentation

abandon()

template<typename T >

auto dpp::awaitable< T >::abandon

protected

Abandons the promise.

Set the promise's state to broken and unlinks this awaitable.

Returns

uint8_t Flags previously held before setting them to broken

await_ready()

template<typename T >

bool dpp::awaitable< T >::await_ready

Check whether or not co_await-ing this would suspend the caller, i.e. if we have the result or not.

Returns

bool Whether we already have the result or not

operator=() [1/2]

template<typename T >

awaitable& dpp::awaitable< T >::operator= ( awaitable< T > &&  rhs )

inlinenoexcept

Move from another awaitable.

Parameters

rhs	The awaitable to move from, left in an unspecified state after this.

Returns

*this

operator=() [2/2]

template<typename T >

awaitable& dpp::awaitable< T >::operator= ( const awaitable< T > &  )

delete

Copy assignment is disabled.

requires() [1/2]

template<typename T >

template<typename Derived >

dpp::awaitable< T >::requires ( std::is_base_of_v< awaitable< T >, std::remove_cv_t< Derived >>  ) &

inlinenoexcept

Overload of the co_await operator.

Returns

Returns an awaiter referencing this awaitable.

requires() [2/2]

template<typename T >

template<typename Derived >

dpp::awaitable< T >::requires ( std::is_base_of_v< awaitable< T >, std::remove_cv_t< Derived >>  ) &&

inlinenoexcept

Overload of the co_await operator. Returns an awaiter referencing this awaitable.

Returns

Returns an awaiter referencing this awaitable.

valid()

template<typename T >

bool dpp::awaitable< T >::valid

noexcept

Check whether this awaitable refers to a valid promise.

Returns

bool Whether this awaitable refers to a valid promise or not

Friends And Related Function Documentation

detail::promise::promise_base< T >

template<typename T >

friend class detail::promise::promise_base< T >

friend

Member Data Documentation

state_ptr

template<typename T >

shared_state* dpp::awaitable< T >::state_ptr = nullptr

protected

Non-owning pointer to the promise, which must be kept alive for the entire lifetime of the awaitable.