StateManager Class Template

Manages state transitions using a rule-based system. More...

Declaration

template <typename StateType> class helios::engine::state::StateManager<StateType> { ... }

Public Member Typedefs Index

template <typename StateType>
using	EngineRoleTag = helios::engine::common::tags::ManagerRole

Public Constructors Index

template <typename StateType>
StateManager (std::span< const StateTransitionRule< StateType > > rules)
	Constructs a state manager with transition rules. More...

Public Member Functions Index

template <typename StateType>
StateManager &	addStateListener (std::unique_ptr< StateTransitionListener< StateType > > listener) noexcept
	Registers a state transition listener. More...
template <typename StateType>
void	flush (helios::engine::runtime::world::UpdateContext &updateContext) noexcept
	Processes pending state commands. More...
template <typename StateType>
bool	submit (const StateCommand< StateType > stateCommand) noexcept
	Submits a state command for processing. More...
template <typename StateType>
void	init (helios::engine::runtime::world::GameWorld &gameWorld)
	Initializes the manager and registers with GameWorld. More...
template <typename StateType>
void	reset ()
	Clears all pending commands. More...

Private Member Functions Index

template <typename StateType>
void	signalExit (const StateType from, const StateType to, const StateTransitionIdType< StateType > transitionId, helios::engine::runtime::world::UpdateContext &updateContext)
	Notifies listeners of state exit. More...
template <typename StateType>
void	signalTransition (const StateType from, const StateType to, const StateTransitionIdType< StateType > transitionId, helios::engine::runtime::world::UpdateContext &updateContext)
	Notifies listeners of the transition. More...
template <typename StateType>
void	signalEnter (const StateType from, const StateType to, const StateTransitionIdType< StateType > transitionId, helios::engine::runtime::world::UpdateContext &updateContext)
	Notifies listeners of state entry. More...

Private Member Attributes Index

template <typename StateType>
std::vector< StateCommand< StateType > >	pending_
	Queue of pending state commands. More...
template <typename StateType>
std::vector< std::unique_ptr< StateTransitionListener< StateType > > >	listeners_
	Registered transition listeners. More...
template <typename StateType>
std::vector< StateTransitionRule< StateType > >	rules_
	Transition rules defining valid state changes. More...

Description

Manages state transitions using a rule-based system.

Implements both Manager and TypedStateCommandHandler interfaces. Processes state transition commands by matching against registered rules, executing guards, and notifying listeners.

## Transition Flow

1. Commands are submitted via submit() and queued 2. During flush(), the last pending command is processed 3. Rules are checked to find a matching transition 4. If a guard is present, it must return true 5. Listeners are notified: onStateExit -> onStateTransition -> onStateEnter 6. Session state is updated

Template Parameters

StateType

The state enum type.

See Also

StateTransitionRule

See Also

StateTransitionListener

See Also

StateCommand

Definition at line 68 of file StateManager.ixx.

Public Member Typedefs

EngineRoleTag

template <typename StateType>

using helios::engine::state::StateManager< StateType >::EngineRoleTag = helios::engine::common::tags::ManagerRole

Definition at line 148 of file StateManager.ixx.

148 using EngineRoleTag = helios::engine::common::tags::ManagerRole;

Public Constructors

StateManager()

template <typename StateType>

helios::engine::state::StateManager< StateType >::StateManager (std::span< const StateTransitionRule< StateType > > rules)

inline explicit

Constructs a state manager with transition rules.

Parameters

rules

Span of valid transition rules.

Definition at line 155 of file StateManager.ixx.

155 explicit StateManager(std::span<const StateTransitionRule<StateType>> rules)

156 : rules_(rules.begin(), rules.end()) {}

Public Member Functions

addStateListener()

template <typename StateType>

StateManager & helios::engine::state::StateManager< StateType >::addStateListener (std::unique_ptr< StateTransitionListener< StateType > > listener)

inline noexcept

Registers a state transition listener.

Parameters

listener

The listener to add.

Returns

Reference to this manager for chaining.

Definition at line 165 of file StateManager.ixx.

165 StateManager& addStateListener(std::unique_ptr<StateTransitionListener<StateType>> listener) noexcept {

166 listeners_.push_back(std::move(listener));

167 return *this;

168 }

flush()

template <typename StateType>

void helios::engine::state::StateManager< StateType >::flush (helios::engine::runtime::world::UpdateContext & updateContext)

inline noexcept

Processes pending state commands.

Processes the last pending command, finds matching rules, executes guards, and triggers the transition if valid.

Parameters

updateContext

The current frame's update context.

Definition at line 178 of file StateManager.ixx.

178 void flush(

179 helios::engine::runtime::world::UpdateContext& updateContext

180 ) noexcept {

181

182 if (pending_.empty()) {

183 return;

184 }

185

186 auto command = pending_.back();

187

188 auto transitionRequest = command.transitionRequest();

189

190 auto& session = updateContext.session();

191 auto currentFrom = session.state<StateType>();

192 auto from = transitionRequest.from();

193 auto transitionId = transitionRequest.transitionId();

194

195

196 if (currentFrom != from) {

197 pending_.clear();

198 return;

199 }

200

201

202 for (auto& rule : rules_) {

203 if (rule.from() == from && rule.transitionId() == transitionId) {

204

205 if (rule.guard()) {

206 if (!rule.guard()(updateContext, transitionRequest)) {

207 break;

208 }

209 }

210

211 signalExit(from, rule.to(), transitionId, updateContext);

212 signalTransition(from, rule.to(), transitionId, updateContext);

213 session.setStateFrom<StateType>(StateTransitionContext<StateType>{rule.from(), rule.to(), transitionId});

214 signalEnter(from, rule.to(), transitionId, updateContext);

215 }

216 }

217

218 pending_.clear();

219 }

init()

template <typename StateType>

void helios::engine::state::StateManager< StateType >::init (helios::engine::runtime::world::GameWorld & gameWorld)

inline

Initializes the manager and registers with GameWorld.

Parameters

gameWorld

The game world to register with.

Definition at line 240 of file StateManager.ixx.

240 void init(helios::engine::runtime::world::GameWorld& gameWorld) {

241 gameWorld.registerCommandHandler<StateCommand<StateType>>(*this);

242 }

reset()

template <typename StateType>

void helios::engine::state::StateManager< StateType >::reset ()

inline

Clears all pending commands.

Definition at line 247 of file StateManager.ixx.

247 void reset() {

248 // intentionally left empty. Clearing the pending queue would also mean

249 // that any pending state transisions **required by the reset** are nuked.

250 }

submit()

template <typename StateType>

bool helios::engine::state::StateManager< StateType >::submit (const StateCommand< StateType > stateCommand)

inline noexcept

Submits a state command for processing.

Parameters

stateCommand

The command to queue.

Returns

True (always accepts commands).

Definition at line 228 of file StateManager.ixx.

228 bool submit(

229 const StateCommand<StateType> stateCommand

230 ) noexcept {

231 pending_.push_back(stateCommand);

232 return true;

233 };

Private Member Functions

signalEnter()

template <typename StateType>

void helios::engine::state::StateManager< StateType >::signalEnter (const StateType from, const StateType to, const StateTransitionIdType< StateType > transitionId, helios::engine::runtime::world::UpdateContext & updateContext)

inline

Notifies listeners of state entry.

Parameters

from	The source state.
to	The state being entered.
transitionId	The transition identifier.
updateContext	The current frame's update context.

Definition at line 134 of file StateManager.ixx.

134 void signalEnter(

135 const StateType from,

136 const StateType to,

137 const StateTransitionIdType<StateType> transitionId,

138 helios::engine::runtime::world::UpdateContext& updateContext) {

139

140 for (auto& listener : listeners_) {

141 listener->onStateEnter(updateContext, to);

142

143 }

144 }

signalExit()

template <typename StateType>

void helios::engine::state::StateManager< StateType >::signalExit (const StateType from, const StateType to, const StateTransitionIdType< StateType > transitionId, helios::engine::runtime::world::UpdateContext & updateContext)

inline

Notifies listeners of state exit.

Parameters

from	The state being exited.
to	The target state.
transitionId	The transition identifier.
updateContext	The current frame's update context.

Definition at line 93 of file StateManager.ixx.

93 void signalExit(

94 const StateType from,

95 const StateType to,

96 const StateTransitionIdType<StateType> transitionId,

97 helios::engine::runtime::world::UpdateContext& updateContext) {

98

99 for (auto& listener : listeners_) {

100 listener->onStateExit(updateContext, from);

101 }

102 }

signalTransition()

template <typename StateType>

void helios::engine::state::StateManager< StateType >::signalTransition (const StateType from, const StateType to, const StateTransitionIdType< StateType > transitionId, helios::engine::runtime::world::UpdateContext & updateContext)

inline

Notifies listeners of the transition.

Parameters

from	The source state.
to	The target state.
transitionId	The transition identifier.
updateContext	The current frame's update context.

Definition at line 112 of file StateManager.ixx.

112 void signalTransition(

113 const StateType from,

114 const StateType to,

115 const StateTransitionIdType<StateType> transitionId,

116 helios::engine::runtime::world::UpdateContext& updateContext) {

117

118 for (auto& listener : listeners_) {

119 listener->onStateTransition(

120 updateContext,

121 StateTransitionContext<StateType>{from, to, transitionId}

122 );

123 }

124 }

Private Member Attributes

listeners_

template <typename StateType>

std::vector<std::unique_ptr<StateTransitionListener<StateType> > > helios::engine::state::StateManager< StateType >::listeners_

Registered transition listeners.

Definition at line 78 of file StateManager.ixx.

78 std::vector<std::unique_ptr<StateTransitionListener<StateType>>> listeners_;

pending_

template <typename StateType>

std::vector<StateCommand<StateType> > helios::engine::state::StateManager< StateType >::pending_

Queue of pending state commands.

Definition at line 73 of file StateManager.ixx.

73 std::vector<StateCommand<StateType>> pending_;

rules_

template <typename StateType>

std::vector<StateTransitionRule<StateType> > helios::engine::state::StateManager< StateType >::rules_

Transition rules defining valid state changes.

Definition at line 83 of file StateManager.ixx.

83 std::vector<StateTransitionRule<StateType>> rules_;

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

• StateManager.ixx

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