(Sorry for duplicates, I did not use my registered email before) Hi there, I've been working with Statecharts and esp. SCXML for a longer time now. I started implementing an interpreter in C# and C++ first for my Diploma-Thesis, which got then published in "Game AI Wisdom 4" and later found use in my companies Point&Click-Adventure Engine. Now i started to work on an interpreter written in ActionScript to get a library that any Flex developer can slap into her RIA/game. So when I came back I found the description of the Algorithm for interpreting SCXML's and that was a great help to re-implement my interpreter. However I stumbled upon a part in the mainEventLoop after implementing it and running some Test-SCXML's... maybe I did not get it right, but I think there maybe a mistake: Take a scxml snipplet like this: <parallel id="InTest"> <state id="s1"> <initial> <transition target="s11"/> </initial> <state id="s11"/> <final id="s12"/> </state> <state id="s2"> <initial> <transition target="s21"/> </initial> <state id="s21"/> <final id="s22"/> </state> <transition event="InTest.Done" target="f"/> </parallel> ....... // now take any newly enabled null transitions and any transitions triggered by internal events macroStepComplete = false; until(macroStepComplete): enabledTransitions = selectEventlessTransitions() if (enabledTransitions.isEmpty()): internalEvent = internalQueue.dequeue()// this call returns immediately if no event is available if (internalEvent): datamodel.assignValue("event", internalEvent) enabledTransitions = selectTransitions(internalEvent) if (enabledTransitions): microstep(enabledTransitions.toList() else: macroStepComplete = true ...... Suppose during the execution of an external event more than one internal event is queued. This happens often if a parallel-state is "Done" and its children are as well. In the case listed above, there would be generated the events s1.Done, s2.Done and InTest.Done in that order (if proper transitions would exist and the events would be fired). During the next macro step, the first internalEvent is dequeued ("s1.Done"), but no transition will be enabled. That would mark the macroStep as complete and no other internal event is handled until the next external event is dispatched. Imho, there should be done something like this more likely: if (enabledTransitions): microstep(enabledTransitions.toList() else: macroStepComplete = internalQueue.isEmpty() So, if the internalQueue is not empty, the macrostep will dequeue the next event in the internal queue. Any opinions? Best regards, Philipp KolhoffReceived on Tuesday, 28 July 2009 08:43:15 GMT
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