ion::SignalToken< T > Class Template Reference

Signal token that has an associated SignalSource and last known value. More...

#include <ion/signal.hpp>

Public Types
using	ValueType = T

Public Member Functions
Initialization.
	SignalToken () noexcept=default
	Default-initialized token.
	SignalToken (SignalSource< T > const *signal, std::optional< ValueType > last=std::nullopt) noexcept
	Initialize token.
	SignalToken (SignalToken const &) noexcept=default
auto	operator= (SignalToken const &) noexcept -> SignalToken &=default
	SignalToken (SignalToken &&other) noexcept
	Move-construct token, leaving other in an invalid state.
auto	operator= (SignalToken &&other) noexcept -> SignalToken &
	Move-assign token, leaving other in an invalid state.
Observers
constexpr auto	IsValid () const noexcept -> bool
auto	Load () const noexcept -> ValueType
constexpr auto	GetSource () const -> SignalSource< ValueType > const *
constexpr auto	GetLast () const noexcept -> ValueType
	Get last observed value.
Modifiers
constexpr void	SetLast (ValueType last) noexcept
	Set last observed value.
auto	Update () noexcept -> ValueType

Related Symbols
(Note that these are not member symbols.)
template<class T>
constexpr auto	operator== (SignalToken< T > const &lhs, SignalToken< T > const &rhs) noexcept -> bool
	Equality comparison.
template<class T>
constexpr auto	operator!= (SignalToken< T > const &lhs, SignalToken< T > const &rhs) noexcept -> bool
	Inequality comparison.
Wait and yield current signal value.
template<class T>
auto	Wait (SignalToken< T > &token) noexcept -> T
	Wait until signal source changes and return current value.
template<class T, class Predicate>
auto	Wait (SignalToken< T > &token, Predicate &&stop_waiting) noexcept -> T
	Wait with predicate.
Wait and yield Status<T>.
template<class T>
auto	Wait (StatusTag, SignalToken< T > &token) noexcept -> Status< T >
	Wait until signal source changes and return current and previous values.
template<class T, class Predicate>
auto	Wait (StatusTag, SignalToken< T > &token, Predicate &&stop_waiting) noexcept -> Status< T >
	Wait with predicate.
Wait and yield changes since last.
template<class T>
auto	Wait (DifferenceTag, SignalToken< T > &token) noexcept -> T
	Wait until signal source changes and return difference (current - previous) value.
template<class T, class Predicate>
auto	Wait (DifferenceTag, SignalToken< T > &token, Predicate &&stop_waiting) noexcept -> T
	Wait until signal source changes and return difference (current - previous) value.
Wait for either of two signals.
Effects Load and compare each of the signals with previous value. The first one to change will be recorded in the WaitAnyResult::index. Depending on the selected overload the result of WaitAnyResult::result is either the current, difference or the Status containing both previous and current value.
template<class T1, class T2>
auto	WaitAny (SignalToken< T1 > &token1, SignalToken< T2 > &token2) noexcept -> WaitAnyResult< T1, T2 >
	Wait for either of two signals to change.
template<class T1, class T2>
auto	WaitAny (StatusTag, SignalToken< T1 > &token1, SignalToken< T2 > &token2) noexcept -> WaitAnyResult< Status< T1 >, Status< T2 > >
	Wait for either of two signals to change.
template<class T1, class T2>
auto	WaitAny (DifferenceTag, SignalToken< T1 > &token1, SignalToken< T2 > &token2) noexcept -> WaitAnyResult< T1, T2 >
	Wait for either of two signals to change.

Detailed Description

template<class T>
class ion::SignalToken< T >

Signal token that has an associated SignalSource and last known value.

A SignalToken is valid (IsValid() == true) if it is associated with a SignalSource.

Moving a SignalToken will leave the moved-from object invalid.

See Signals for example.

Thread Safety

thread-compatible

Constructor & Destructor Documentation

SignalToken() [1/3]

template<class T>

ion::SignalToken< T >::SignalToken ( )

defaultnoexcept

Default-initialized token.

Postcondition

IsValid() == false

SignalToken() [2/3]

template<class T>

ion::SignalToken< T >::SignalToken ( SignalSource< T > const * signal, std::optional< ValueType > last = std::nullopt )

explicitnoexcept

Initialize token.

Parameters

signal	Associated signal.
last	Optional value to set as last known signal value. If nullopt is used and signal is valid the last value will be initialized from signal source.

SignalToken() [3/3]

template<class T>

ion::SignalToken< T >::SignalToken ( SignalToken< T > && other )

noexcept

Move-construct token, leaving other in an invalid state.

Parameters

other

SignalToken to move from.

Postcondition

other.IsValid() == false

Member Function Documentation

GetSource()

template<class T>

auto ion::SignalToken< T >::GetSource ( ) const -> SignalSource< ValueType > const *

nodiscardconstexpr

Returns

Signal source associated with this SignalToken.

IsValid()

template<class T>

auto ion::SignalToken< T >::IsValid ( ) const -> bool

nodiscardconstexprnoexcept

Returns

true if SignalToken is associated with a SignalSource.

false otherwise.

Load()

template<class T>

auto ion::SignalToken< T >::Load ( ) const -> ValueType

nodiscardnoexcept

  Loads signal value but *does not* set last value.

  @pre `IsValid() == true`
  @sa Update()
  \par Memory Order
 \parblock Loads value from associated signal source using relaxed memory order (no

synchronize-with relationships).

operator=()

template<class T>

auto ion::SignalToken< T >::operator= ( SignalToken< T > && other ) -> SignalToken &

noexcept

Move-assign token, leaving other in an invalid state.

Parameters

other

SignalToken to move from.

Postcondition

other.IsValid() == false

SetLast()

template<class T>

void ion::SignalToken< T >::SetLast ( ValueType last )

constexprnoexcept

Set last observed value.

Parameters

last	Value to set as "last" known value from signal.

Update()

template<class T>

auto ion::SignalToken< T >::Update ( ) -> ValueType

noexcept

  Load from signal and set last value.

  @pre IsValid() == true
  @return New signal source value.
  @post `r.Update() == r.GetLast()`
  @sa Load()
  \par Memory Order
 \parblock Loads value from associated signal source using relaxed memory order (no

synchronize-with relationships).