PureStateMachine< StateType > Class Template Reference

A minimal and flexible finite state machine (FSM) implementation. More...

#include <state_machine.hpp>

Classes
struct	Event
	Represents a state-related event emitted during an update. More...
struct	Transition
	Represents a possible transition from one state to another. More...

Public Types
enum class	EventType { ENTER_STATE , UPDATE_STATE , EXIT_STATE , TRANSITION }
	The type of event emitted by the state machine. More...
enum class	Mode { MULTI_EVENT , SINGLE_EVENT }
	Determines how many events are emitted per update tick. More...
using	Condition = std::function<bool()>

Public Member Functions
	PureStateMachine (StateType initial_state, Mode mode=Mode::MULTI_EVENT)
	Constructs a new PureStateMachine with an initial state and mode.
void	add_state (StateType state)
	Adds a new state to the machine.
void	add_transition (StateType from, StateType to, Condition condition)
	Adds a conditional transition between two states.
std::vector< Event >	update_pure ()
	Updates the state machine and emits events describing what happened.
StateType	get_state () const
	Gets the current state.
void	set_mode (Mode new_mode)
	Sets the current operational mode of the FSM.
Mode	get_mode () const
	Gets the current operational mode.

Detailed Description

template<typename StateType>
class PureStateMachine< StateType >

A minimal and flexible finite state machine (FSM) implementation.

This class provides a generic state machine framework that can operate in two modes:

• MULTI_EVENT: Emits multiple events per update (enter, update, exit, and transition).
• SINGLE_EVENT: Emits only one event per update, suitable for systems that process one event at a time.

It does not perform side effects directly—only emits Event objects describing what happened. Users can then handle these events externally in their own systems.

Template Parameters

StateType

The enum or integral type representing all possible states.

Member Typedef Documentation

Condition

template<typename StateType>

using PureStateMachine< StateType >::Condition = std::function<bool()>

Member Enumeration Documentation

EventType

template<typename StateType>

enum class PureStateMachine::EventType

strong

The type of event emitted by the state machine.

Enumerator
ENTER_STATE	Indicates entry into a new state.
UPDATE_STATE	Indicates the current state is being updated.
EXIT_STATE	Indicates exit from a previous state.
TRANSITION	Indicates a transition between two states.

Mode

template<typename StateType>

enum class PureStateMachine::Mode

strong

Determines how many events are emitted per update tick.

Enumerator
MULTI_EVENT	Default mode: may emit multiple events per tick.
SINGLE_EVENT	Alternate mode: only one event per tick.

Constructor & Destructor Documentation

PureStateMachine()

template<typename StateType>

PureStateMachine< StateType >::PureStateMachine ( StateType initial_state, Mode mode = Mode::MULTI_EVENT )

inlineexplicit

Constructs a new PureStateMachine with an initial state and mode.

Parameters

initial_state	The starting state of the machine.
mode	The event emission mode (default: MULTI_EVENT).

Member Function Documentation

add_state()

template<typename StateType>

void PureStateMachine< StateType >::add_state ( StateType state )

inline

Adds a new state to the machine.

Parameters

state

The state to add.

add_transition()

template<typename StateType>

void PureStateMachine< StateType >::add_transition ( StateType from, StateType to, Condition condition )

inline

Adds a conditional transition between two states.

Parameters

from	The state from which the transition originates.
to	The state to transition to.
condition	A callable returning true if the transition should occur.

get_mode()

template<typename StateType>

Mode PureStateMachine< StateType >::get_mode ( ) const

inlinenodiscard

Gets the current operational mode.

Returns

The current mode.

get_state()

template<typename StateType>

StateType PureStateMachine< StateType >::get_state ( ) const

inlinenodiscard

Gets the current state.

Returns

The current state.

set_mode()

template<typename StateType>

void PureStateMachine< StateType >::set_mode ( Mode new_mode )

inline

Sets the current operational mode of the FSM.

Parameters

new_mode

The new mode to use.

update_pure()

template<typename StateType>

std::vector< Event > PureStateMachine< StateType >::update_pure ( )

inlinenodiscard

Updates the state machine and emits events describing what happened.

The emitted events depend on the current mode:

• In MULTI_EVENT mode, multiple events may be emitted per tick (enter, update, transition, etc.).
• In SINGLE_EVENT mode, only one event is emitted per tick.

Returns

A vector of events representing what occurred during the update.

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

• src/utility/state_machine/state_machine.hpp