rinde.sim.util.fsm.State Maven / Gradle / Ivy
package rinde.sim.util.fsm;
import javax.annotation.Nullable;
/**
* Defines a state in a state machine.
*
* @param Event type, see {@link StateMachine} for details.
* @param Context type, see {@link StateMachine} for details.
* @author Rinde van Lon
*/
public interface State {
/**
* @return The name of the state.
*/
String name();
/**
* Should handle the event. Allows the state to take control and react to the
* event.
* @param event The event that should be handled.
* @param context The context of the state.
* @return An event or null. If null is returned
* there will be no state transition. If the returned event is not
* supported by this state (as defined by the {@link StateMachine}) a
* {@link RuntimeException} will be thrown by the {@link StateMachine}
* .
*/
@Nullable
E handle(@Nullable E event, C context);
/**
* This method is called at the moment the {@link StateMachine} 'enters' this
* state (i.e. during a state transition). It is called just before the
* {@link #handle(Object, Object)} is called.
* @param event The event that triggered the transition.
* @param context The context of the state.
*/
void onEntry(E event, C context);
/**
* This method is called at the moment the {@link StateMachine} 'exits' this
* state (i.e. during a state transition).
* @param event The event that triggered the transition.
* @param context The context of the state.
*/
void onExit(E event, C context);
}