Exit a State
When there is a valid transition out of a state, that state is marked for exit. A state is marked for exit in one of these ways:
The outgoing transition originates at the state boundary.
The outgoing transition crosses the state boundary.
The destination state is a parallel state child of an activated state.
Workflow for Exiting a State
This flow chart shows the progression of events in Stateflow® for exiting a state. In this flow chart, the current state refers to the state in which a decision or a process is taking place.
Exit Actions
Exit actions for a state execute when the state is active and a
valid transition from the state exists. A state performs its exit
actions before becoming inactive.
Exit actions are preceded by the prefix exit or
ex, followed by a required colon (:), and then
followed by one or more actions. Separate multiple actions with a carriage return,
semicolon (;), or a comma (,).
Exit a State Example
In this example, the Stateflow chart is initialized and the entry actions are
performed for StateA and StateA1. For this chart,
the during actions for this chart have occurred twice. A new time
step occurs, and then the chart wakes up.
By following the Workflow for Stateflow Chart Execution and the Workflow for Evaluating Transitions,
StateB has been marked for entry. StateA is the
source of the transition. At this time step x = 5, y =
2, and z = 0.
By following the flow chart for state exit actions until the chart goes to sleep, the execution steps for this chart are in this order:
StateAis not a superstate ofStateB.Perform the exit actions of
StateAand markStateAas inactive. Nowz = 1.StateAdoes not have a parent state.Go to Entry Actions.
These steps complete the exit workflow for
StateA. However, the chart is not yet asleep.
Perform the Workflow for Entering a Chart or State for
StateB to complete the time step.
Exit a State by Using Supertransitions
A supertransition is a transition between different levels in a chart. A supertransition can be between a state in a top-level chart and a state in one of its substates, or between states residing in different substates. You can create supertransitions that span any number of levels in your chart.
When a state is exited through a supertransition, after the exit actions for the
source of the transition are executed, its superstates are marked inactive and exit
actions of the superstates are executed. In this example, StateA2 is
marked for exit and StateB1 is marked for
entry. At this point, x = 5, y =
5, and z = 0.
By following the Workflow for Entering a Chart or State until the chart
goes to sleep, the execution steps for exiting the state StateA2 are
in this order:
StateA2is not a superstate of the destination state (StateB1).Perform the
exitactions forStateA2and markStateA2as inactive.StateA2does have a parent state,StateA.StateAis not a superstate of the destination state (StateB1).Perform the
exitactions forStateA, and markStateAas inactive.StateAdoes not have a parent state.
These actions complete the exit workflow for
StateA2 and StateA. However, the chart is not
yet asleep.
Perform the Workflow for Entering a Chart or State for
StateB and StateB1 to complete the time
step.