/// <summary>
/// Invoked to execute the state machine.
/// </summary>
/// <param name="e">Provides an optional event type to post at normal priority before starting execution</param>
/// <returns>A value of type R</returns>
/// <exception cref="System.InvalidOperationException">Thrown if an event is chosen for
/// execution and no transition from the current state maches the event.
/// </exception>
/// <exception cref="EnteredErrorStateException">Thrown if execution enters an error state</exception>
/// <remarks>
/// The state machine runs until one of the following conditions is met:
/// - There are no remaining events to process
/// - A stop or error state is entered
/// - An event is encountered and no transition matches the event type
/// - An action raises an exception
/// For each state, the next event to be processed is chosen from the head of the
/// internal event queue, and if no event is found, then the external event queue.
/// </remarks>
public R Execute(int?e)
{
if (e.HasValue)
{
PostNormalPriorityEvent(e.Value);
}
R returnValue = default;
switch (ExecutionState)
{
case ExecutionStates.Idle:
ExecutionState = ExecutionStates.Executing;
while (StateClassifications[CurrentState] == StateTypes.Normal && (CurrentEvent = GetNextEvent()).HasValue)
{
EventTrace.Add(new EventTraceInstance(CurrentState, CurrentEvent.Value));
Transition <Action> transition = Transitions[CurrentState, CurrentEvent.Value];
foreach (Action a in transition.Actions)
{
try
{
returnValue = a();
}
catch (UnexpectedEventException)
{
throw;
}
catch (Exception exc)
{
ExecutionState = ExecutionStates.Exception;
throw new ActionRaisedException(this,
(CurrentState >= StateNames.GetLowerBound(0) && CurrentState <= StateNames.GetUpperBound(0) ? StateNames[CurrentState] : CurrentState.ToString()),
exc);
}
}
CurrentState = transition.NextState;
}
if (StateClassifications[CurrentState] == StateTypes.Error)
{
ExecutionState = ExecutionStates.Errored;
throw new EnteredErrorStateException(this,
(CurrentEvent.Value >= EventNames.GetLowerBound(0) && CurrentEvent.Value <= EventNames.GetUpperBound(0) ? EventNames[CurrentEvent.Value] : CurrentEvent.Value.ToString()),
(CurrentState >= StateNames.GetLowerBound(0) && CurrentState <= StateNames.GetUpperBound(0) ? StateNames[CurrentState] : CurrentState.ToString()));
}
ExecutionState = ExecutionStates.Idle;
return(returnValue);
case ExecutionStates.Errored:
case ExecutionStates.Exception:
throw new EnteredErrorStateException(this,
(CurrentEvent.Value >= EventNames.GetLowerBound(0) && CurrentEvent.Value <= EventNames.GetUpperBound(0) ? EventNames[CurrentEvent.Value] : CurrentEvent.Value.ToString()),
(CurrentState >= StateNames.GetLowerBound(0) && CurrentState <= StateNames.GetUpperBound(0) ? StateNames[CurrentState] : CurrentState.ToString()));
case ExecutionStates.Executing:
case ExecutionStates.Finished:
return(returnValue);
default:
throw new NotImplementedException();
}
}
/// <summary>
/// Invoked when none of the transitions for the current state have a trigger event matching the current event type
/// </summary>
protected R InvalidTransition()
{
throw new UnexpectedEventException(this,
(CurrentEvent.Value >= EventNames.GetLowerBound(0) && CurrentEvent.Value <= EventNames.GetUpperBound(0) ? EventNames[CurrentEvent.Value] : CurrentEvent.Value.ToString()),
(CurrentState >= StateNames.GetLowerBound(0) && CurrentState <= StateNames.GetUpperBound(0) ? StateNames[CurrentState] : CurrentState.ToString()));
}