[Qt-interest] eventTest() and parallel states in QStateMachine

[Daniel Zollinger]

OK, now I got your point, Thanks a lot!

2011/2/10 <noam.rosenthal at nokia.com>

>
> Right. In that case there's nothing much you can do on the algorithm level.
>
...

> That is if you design your statechart in the way you describe, which counts
> on the assumption that eventTest would be called only once, that is
> apparently not something you can count on :)
>

You're right, but the algorithm could be much more powerful, if someone
could rely on only one invocation of eventTest().
As far as I understand, the problem arises because of the common ancestry of
parallel states. If selectTransition would remember the already handled
states, the transitions would be tested only once.

function selectTransitions(event):
    enabledTransitions = new OrderedSet()
 +  handledStates = new OrderedSet()
    atomicStates =
configuration.toList().filter(isAtomicState).sort(documentOrder)
    for state in atomicStates:
        if not isPreempted(state, enabledTransitions):
            loop: for s in [state].append(getProperAncestors(state, null)):
+               if !handledStates.contains(s):
+                   handledStates.add(s)
                    for t in s.transition:
                        if t.event and nameMatch(t.event, event.name)
and conditionMatch(t):
                            enabledTransitions.add(t)
                            break loop
    return enabledTransitions

I'm not familiar with lisp, so I don't know whether or not to delete
handledStates at the end of selectTransitons, but I think you get my point.
:-)

Daniel
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