This class models a state machine. It keeps track of the current state and allows to invoke its associated state function. The return value of the state function determines the new state to transition into. Additionally, a context of type StateMachineContext can be assigned to the state machine. Contexts allow for replacing states with other states. This makes sense to write inner protocols BeginState -> StateA -> ... -> StateN -> EndState and to embed them into outer protocols. The outer protocol can transition into BeginState and take control back by replacing EndState with one of its own states by setting a respective context. All states (of type StateMachineState) have to be registered upon construction of the StateMachine instance. More...

Public Types
using	StateType = StateMachineStateT

using	StateEnumType = typename StateType::StateEnumType
	Refer to class StateMachineState. More...

using	ContextType = StateMachineContext< StateMachineStateT >

Public Member Functions
template<typename... StateMachineStateTs>
	StateMachine (const StateType &InitialState, const StateMachineStateTs &... States)
	Constructs a state machine assigning possible states to it. Automatically also adds `InitialState`, so don't include it into `States`. More...

const StateType *	GetCurrentState () const noexcept
	Returns a pointer to the current state. More...

const ContextType *	GetContext () const noexcept
	Returns a pointer to the current context. More...

void	SetCurrentState (StateEnumType NewState)
	Sets the current state as identified by an element from `StateEnumType`. More...

void	SetContext (const ContextType *NewContext)
	Sets the current state machine context. More...

void	ResetContext ()
	Removes the current state machine context. More...

template<typename... ArgTs>
void	Invoke (instance_of_t< typename StateType::CallableType > &Instance, ArgTs &&... Args)
	Invokes the state function associated with the current state machine state on an instance of the class the state functions are member functions of. Refer to class StateMachineState. Also sets the state machine's state to the return value of the state function. More...

Private Attributes
const std::unordered_map< StateEnumType, const StateType * >	StatesList
	Map of possible states. All states are uniquely identified by an element from `StateEnumType`. Refer to StateMachineState. More...

Atomic members for thread-safety
Atomic to allow reading the current state and context from one thread and setting the current state and context from another thread without further synchronization.
std::atomic< const StateType * >	CurrentState

std::atomic< const ContextType * >	CurrentContext

Detailed Description

template<typename StateMachineStateT>
class Util::StateMachine< StateMachineStateT >

This class models a state machine. It keeps track of the current state and allows to invoke its associated state function. The return value of the state function determines the new state to transition into. Additionally, a context of type StateMachineContext can be assigned to the state machine. Contexts allow for replacing states with other states. This makes sense to write inner protocols BeginState -> StateA -> ... -> StateN -> EndState and to embed them into outer protocols. The outer protocol can transition into BeginState and take control back by replacing EndState with one of its own states by setting a respective context. All states (of type StateMachineState) have to be registered upon construction of the StateMachine instance.

Template Parameters

StateMachineStateT State type of type StateMachineState the state machine operates on

Definition at line 1434 of file Util.h.

Member Typedef Documentation

◆ ContextType

template<typename StateMachineStateT >

using Util::StateMachine< StateMachineStateT >::ContextType = StateMachineContext<StateMachineStateT>

Definition at line 1439 of file Util.h.

◆ StateEnumType

template<typename StateMachineStateT >

using Util::StateMachine< StateMachineStateT >::StateEnumType = typename StateType::StateEnumType

Refer to class StateMachineState.

Definition at line 1438 of file Util.h.

◆ StateType

template<typename StateMachineStateT >

using Util::StateMachine< StateMachineStateT >::StateType = StateMachineStateT

Definition at line 1437 of file Util.h.

Constructor & Destructor Documentation

◆ StateMachine()

template<typename StateMachineStateT >

template<typename... StateMachineStateTs>

Util::StateMachine< StateMachineStateT >::StateMachine	(	const StateType &	InitialState,
		const StateMachineStateTs &...	States
	)

inline

Constructs a state machine assigning possible states to it. Automatically also adds InitialState, so don't include it into States.

Template Parameters

...StateMachineStateTs Type of the States parameter pack

Parameters

InitialState	Initial state of the state machine.
...States	Possible states the state machine can transition into. Pass states by reference to prevent from null pointers.

Definition at line 1450 of file Util.h.

Member Function Documentation

◆ GetContext()

template<typename StateMachineStateT >

const ContextType* Util::StateMachine< StateMachineStateT >::GetContext ( ) const

inlinenoexcept

Returns a pointer to the current context.

Definition at line 1456 of file Util.h.

◆ GetCurrentState()

template<typename StateMachineStateT >

const StateType* Util::StateMachine< StateMachineStateT >::GetCurrentState ( ) const

inlinenoexcept

Returns a pointer to the current state.

Definition at line 1455 of file Util.h.

◆ Invoke()

template<typename StateMachineStateT >

template<typename... ArgTs>

void Util::StateMachine< StateMachineStateT >::Invoke	(	instance_of_t< typename StateType::CallableType > &	Instance,
		ArgTs &&...	Args
	)

inline

Invokes the state function associated with the current state machine state on an instance of the class the state functions are member functions of. Refer to class StateMachineState. Also sets the state machine's state to the return value of the state function.

Template Parameters

...ArgTs Type of the parameter pack to forward to the state function

Parameters

Instance	Instance to invoke the state function on
...Args	Parameters to forward to the state function

Exceptions

InvalidStateException is thrown if the current state is nullptr.

Definition at line 1492 of file Util.h.

◆ ResetContext()

template<typename StateMachineStateT >

void Util::StateMachine< StateMachineStateT >::ResetContext ( )

inline

Removes the current state machine context.

Definition at line 1480 of file Util.h.

◆ SetContext()

template<typename StateMachineStateT >

void Util::StateMachine< StateMachineStateT >::SetContext ( const ContextType * NewContext )

inline

Sets the current state machine context.

Parameters

NewContext Context to set

Definition at line 1475 of file Util.h.

◆ SetCurrentState()

template<typename StateMachineStateT >

void Util::StateMachine< StateMachineStateT >::SetCurrentState ( StateEnumType NewState )

inline

Sets the current state as identified by an element from StateEnumType.

Parameters

NewState Identifier of the new state machine state

Exceptions

throw std::out_of_range is thrown if NewState does not exist in StatesList.

Definition at line 1463 of file Util.h.

Member Data Documentation

◆ CurrentContext

template<typename StateMachineStateT >

std::atomic<const ContextType*> Util::StateMachine< StateMachineStateT >::CurrentContext

private

Definition at line 1516 of file Util.h.

◆ CurrentState

template<typename StateMachineStateT >

std::atomic<const StateType*> Util::StateMachine< StateMachineStateT >::CurrentState

private

Definition at line 1515 of file Util.h.

◆ StatesList

template<typename StateMachineStateT >

const std::unordered_map<StateEnumType, const StateType*> Util::StateMachine< StateMachineStateT >::StatesList

private

Map of possible states. All states are uniquely identified by an element from StateEnumType. Refer to StateMachineState.

Definition at line 1508 of file Util.h.

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

Util.h

Public Types

Public Member Functions

Private Attributes

Detailed Description

template<typename StateMachineStateT> class Util::StateMachine< StateMachineStateT >

Member Typedef Documentation

◆ ContextType

◆ StateEnumType

◆ StateType

Constructor & Destructor Documentation

◆ StateMachine()

Member Function Documentation

◆ GetContext()

◆ GetCurrentState()

◆ Invoke()

◆ ResetContext()

◆ SetContext()

◆ SetCurrentState()

Member Data Documentation

◆ CurrentContext

◆ CurrentState

◆ StatesList

template<typename StateMachineStateT>
class Util::StateMachine< StateMachineStateT >