Promise type that allows waiting for a result in both synchronous and asynchronous code. More...

#include <asyncpp/promise.h>

Public Types
using	result_type = TResult

Public Member Functions
	promise ()
	Construct a new promise object in its pending state.

	promise (const promise &other)
	Copy constructor.

promise &	operator= (const promise &other)
	Copy assignment.

bool	is_pending () const noexcept
	Check if the promise is pending.

bool	is_fulfilled () const noexcept
	Check if the promise is fulfilled.

bool	is_rejected () const noexcept
	Check if the promise is rejected.

void	fulfill (auto &&value)
	Fulfill the promise with a value.

bool	try_fulfill (auto &&value)
	Try to fulfill the promise with a value.

void	reject (std::exception_ptr error)
	Reject the promise with an exception.

bool	try_reject (std::exception_ptr error)
	Try to reject the promise with an exception.

template<typename TException , typename... Args>
void	reject (Args &&... args)
	Reject the promise with an exception.

template<typename TException , typename... Args>
bool	try_reject (Args &&... args)
	Try to reject the promise with an exception.

void	then (std::function< void(const TResult &)> then_cb, std::function< void(const std::exception_ptr &)> catch_cb)
	Register a callback to be executed once a result is available. If the promise is not pending the callback is directly executed.

void	on_settle (std::function< void()> settle_cb)
	Register a callback to be executed once a result is available. If the promise is not pending the callback is directly executed.

TResult &	get () const
	Synchronously get the result. If the promise is rejected the rejecting exception gets thrown.

template<class Rep , class Period >
TResult *	get (std::chrono::duration< Rep, Period > timeout) const
	Synchronously get the result with a timeout. If the promise is rejected the rejecting exception gets thrown.

std::pair< TResult *, std::exception_ptr >	try_get (std::nothrow_t) const noexcept
	Synchronously try get the result. If the promise is rejected the rejecting exception gets thrown.

TResult *	try_get () const
	Synchronously try get the result. If the promise is rejected the rejecting exception gets thrown.

auto	operator co_await () const noexcept
	Asynchronously get the result. If the promise is rejected the rejecting exception gets thrown.

Static Public Member Functions
static promise	make_fulfilled (TResult &&value)
	Get a fufilled promise with the specified value.

static promise	make_rejected (std::exception_ptr exception)
	Get a rejected promise with the specified exception.

template<typename TException , typename... Args>
static promise	make_rejected (Args &&... args)
	Get a rejected promise with the specified exception.

Protected Types
using	state = detail::promise_state<TResult, std::exception_ptr>

Protected Attributes
ref< state >	m_state {}

Detailed Description

template<typename TResult>
class asyncpp::promise< TResult >

Promise type that allows waiting for a result in both synchronous and asynchronous code.

Template Parameters

TResult Type of the result

Member Function Documentation

◆ fulfill()

template<typename TResult >

void asyncpp::promise< TResult >::fulfill ( auto && value )

inline

Fulfill the promise with a value.

Exceptions

std::logic_error if the promise is already fulfilled or rejected.

Parameters

value The value to store inside the promise

Note: Callbacks and waiting coroutines are resumed inside this call.

◆ get() [1/2]

template<typename TResult >

TResult & asyncpp::promise< TResult >::get ( ) const

inline

Synchronously get the result. If the promise is rejected the rejecting exception gets thrown.

Returns: TResult& Reference to the result value

◆ get() [2/2]

template<typename TResult >

template<class Rep , class Period >

TResult * asyncpp::promise< TResult >::get ( std::chrono::duration< Rep, Period > timeout ) const

inline

Synchronously get the result with a timeout. If the promise is rejected the rejecting exception gets thrown.

Returns: TResult* Pointer to the result value or nullptr on timeout

◆ is_fulfilled()

template<typename TResult >

bool asyncpp::promise< TResult >::is_fulfilled ( ) const

inlinenoexcept

Check if the promise is fulfilled.

Note: Unlike is_pending() this value is permanent.

Returns: true if the promise contains a value.

◆ is_pending()

template<typename TResult >

bool asyncpp::promise< TResult >::is_pending ( ) const

inlinenoexcept

Check if the promise is pending.

Note: This is a temporary snapshot and should only be used for logging. Consider the returned value potentially invalid by the moment the call returns.

◆ is_rejected()

template<typename TResult >

bool asyncpp::promise< TResult >::is_rejected ( ) const

inlinenoexcept

Check if the promise is rejected.

Note: Unlike is_pending() this value is permanent.

Returns: true if the promise contains an exception.

◆ make_fulfilled()

template<typename TResult >

static promise asyncpp::promise< TResult >::make_fulfilled ( TResult && value )

inlinestatic

Get a fufilled promise with the specified value.

Parameters

value Value for the fulfilled promise

Returns: A promise in its fulfilled state

◆ make_rejected() [1/2]

template<typename TResult >

template<typename TException , typename... Args>

static promise asyncpp::promise< TResult >::make_rejected ( Args &&... args )

inlinestatic

Get a rejected promise with the specified exception.

Template Parameters

TException The type of the exception to store

Parameters

args	Parameters to pass to the exception type constructor

Returns: A promise in its rejected state

◆ make_rejected() [2/2]

template<typename TResult >

static promise asyncpp::promise< TResult >::make_rejected ( std::exception_ptr exception )

inlinestatic

Get a rejected promise with the specified exception.

Parameters

exception Exception to store in the rejected promise

Returns: A promise in its rejected state

◆ on_settle()

template<typename TResult >

void asyncpp::promise< TResult >::on_settle ( std::function< void()> settle_cb )

inline

Register a callback to be executed once a result is available. If the promise is not pending the callback is directly executed.

Parameters

cb	Callback to invoke as soon as a result is available.

◆ operator co_await()

template<typename TResult >

auto asyncpp::promise< TResult >::operator co_await ( ) const

inlinenoexcept

Asynchronously get the result. If the promise is rejected the rejecting exception gets thrown.

Returns: TResult& Pointer to the result value

◆ reject() [1/2]

template<typename TResult >

template<typename TException , typename... Args>

void asyncpp::promise< TResult >::reject ( Args &&... args )

inline

Reject the promise with an exception.

Exceptions

std::logic_error if the promise is already fulfilled or rejected

Template Parameters

TException The exception type to use for rejection

Parameters

args	Arguments passed to the constructor of the exception type

Note: Callbacks and waiting coroutines are resumed inside this call

◆ reject() [2/2]

template<typename TResult >

void asyncpp::promise< TResult >::reject ( std::exception_ptr error )

inline

Reject the promise with an exception.

Exceptions

std::logic_error if the promise is already fulfilled or rejected

Parameters

ex	The exception to use for rejection

Note: Callbacks and waiting coroutines are resumed inside this call

◆ then()

template<typename TResult >

void asyncpp::promise< TResult >::then	(	std::function< void(const TResult &)>	then_cb,
		std::function< void(const std::exception_ptr &)>	catch_cb )

inline

Register a callback to be executed once a result is available. If the promise is not pending the callback is directly executed.

Parameters

cb	Callback to invoke as soon as a result is available.

◆ try_fulfill()

template<typename TResult >

bool asyncpp::promise< TResult >::try_fulfill ( auto && value )

inline

Try to fulfill the promise with a value.

Returns: True if the promise was fulfilled, false if the promise was not pending

Parameters

value The value to store inside the promise

Note: Callbacks and waiting coroutines are resumed inside this call.

◆ try_get() [1/2]

template<typename TResult >

TResult * asyncpp::promise< TResult >::try_get ( ) const

inline

Synchronously try get the result. If the promise is rejected the rejecting exception gets thrown.

Returns: TResult* Pointer to the result value or nullptr on timeout

◆ try_get() [2/2]

template<typename TResult >

std::pair< TResult *, std::exception_ptr > asyncpp::promise< TResult >::try_get ( std::nothrow_t ) const

inlinenoexcept

Synchronously try get the result. If the promise is rejected the rejecting exception gets thrown.

Returns: TResult* Pointer to the result value or nullptr on timeout

◆ try_reject() [1/2]

template<typename TResult >

template<typename TException , typename... Args>

bool asyncpp::promise< TResult >::try_reject ( Args &&... args )

inline

Try to reject the promise with an exception.

Returns: True if the promise was rejected, false if the promise was not pending

Template Parameters

TException The exception type to use for rejection

Parameters

args	Arguments passed to the constructor of the exception type

Note: Callbacks and waiting coroutines are resumed inside this call

◆ try_reject() [2/2]

template<typename TResult >

bool asyncpp::promise< TResult >::try_reject ( std::exception_ptr error )

inline

Try to reject the promise with an exception.

Returns: True if the promise was rejected, false if the promise was not pending

Parameters

ex	The exception to use for rejection

Note: Callbacks and waiting coroutines are resumed inside this call

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

asyncpp/promise.h

Public Types

Public Member Functions

Static Public Member Functions

Protected Types

Protected Attributes

Detailed Description

Member Function Documentation

◆ fulfill()

◆ get() [1/2]

◆ get() [2/2]

◆ is_fulfilled()

◆ is_pending()

◆ is_rejected()

◆ make_fulfilled()

◆ make_rejected() [1/2]

◆ make_rejected() [2/2]

◆ on_settle()

◆ operator co_await()

◆ reject() [1/2]

◆ reject() [2/2]

◆ then()

◆ try_fulfill()

◆ try_get() [1/2]

◆ try_get() [2/2]

◆ try_reject() [1/2]

◆ try_reject() [2/2]