StateMachine

In UML, a StateMachine is a Behavior that expresses the event-driven Behavior of a system element by traversing a graph of States through Transitions triggered by Event occurrences.

SimpleModeling uses a StateMachine when Transition rules carry central meaning in the Domain Model. It does not introduce a StateMachine for every State; it first determines whether State, Constraints, and Operation contracts are sufficient.

The canonical core boundary in simplemodeling-lib consists of StateMachine[S, E] , State , Transition[S, E] , Guard[S, E] , and Effect[S, E] . Transition candidates are selected by current State and Event, ordered by ascending priority and declaration order for ties, and the first candidate is selected. A Guard Failure stops processing as an evaluation failure rather than being treated as a non-match.