18/5 - 2007 1

VIP Elevator – second model

A VDM++ Project

Made By: Sune Wolff

18/5 - 2007 2

Agenda

Summary of First Model Desired Improvements Class Diagram Mapping Intelligent Elevator Intelligent Queue Achieved Improvements

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Summary of First Model

Basic first model FIFO queue for placing orders

Using ordered sequence of floors Elevator moved between floors in

atomic fashion

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Desired Improvements

Introduce classes for buttons and sensors Make use of mapping

Make elevator more intelligent Keep track of direction Choose next floor based on direction and distance

Introduce automatic test Read test sequence from file

Make sure the VIP receives special treatment No neighbours in elevator when VIP wants to use it Execute VIP order as soon as possible

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Class DiagramWorld

Run()World()

Environment

Environment()

-environment

Elevator

VipExit()VipEnter()Elevator()MoveElevator()NeighbourExit()NeighbourEnter()ActivateSensor()PushOuterButton()UpdateCurrent()PushInnerButton()UpdateDir()

Queue

Queue()QueueFull()QueueEmpty()PutInQueue()GetNextFromQueue()

EC

EC()

-ec

+$elevator

+$vipQueue

+$innerQueue

+$outerQueue

Turnstile

locked : bool

Turnstile()LockTurnstile()UnlockTurnstile()IsTurnstileLocked()

+$tsController

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Mapping

class ECinstance variables public static floorMap : map Elevator`Floor to nat :=

{<none> |-> -1, <ground> |-> 0, <one> |-> 1, <two> |-> 2, <three> |-> 3, <penthouse> |->

4}; public static invFloorMap : map nat to Elevator`Floor := inverse floorMap;end EC

class Elevatoroperations public UpdateCurrent: Dir * Floor ==> Floor UpdateCurrent(dir, cur) == (dcl curNum : nat := EC`floorMap(cur); if (dir = <up> and cur <> <penthouse>) then curNum := curNum + 1 elseif (dir = <down> and cur <> <ground>) then curNum := curNum – 1; return EC`invFloorMap (curNum); );end Elevator

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Intelligent Elevator

public MoveElevator: () ==> Floor MoveElevator() == (if (not EC`vipQueue.QueueEmpty() and EC`innerQueue.QueueEmpty()) then (nextFloor := EC`vipQueue.GetNextFromQueue(direction, currentFloor, nextFloor); currentFloor := UpdateCurrent(direction, currentFloor); return nextFloor) elseif (not EC`innerQueue.QueueEmpty()) then (nextFloor := EC`innerQueue.GetNextFromQueue(direction, currentFloor, nextFloor); currentFloor := UpdateCurrent(direction, currentFloor); return nextFloor) elseif (not EC`outerQueue.QueueEmpty()) then (nextFloor := EC`outerQueue.GetNextFromQueue(direction, currentFloor, nextFloor); currentFloor := UpdateCurrent(direction, currentFloor); return nextFloor) else (UpdateDir(direction); return <none>;

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Intelligent Queue

public GetNextFromQueue: Elevator`Dir * Elevator`Floor * Elevator`Floor ==> [Elevator`Floor]

GetNextFromQueue(dir, cur, next) == (dcl nextFloor : Elevator`Floor := next; dcl nextSet : set of Elevator`Floor := {}; dcl top : Elevator`Floor := <penthouse>; dcl bottom : Elevator`Floor := <ground>; for all f in set elevatorQueue do (if (dir = <up> and EC`floorMap(f) > EC`floorMap(cur)) then (nextSet := nextSet union {f}; for all nextF in set nextSet do (if (next = <none>) then (if (EC`floorMap(nextF) < EC`floorMap(top)) then (nextFloor := nextF; top := nextF;) elseif (EC`floorMap(nextF) < EC`floorMap(nextFloor)) then nextFloor := nextF;

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Intelligent Queue #2

if (nextFloor <> next and next <> <none>)then (elevatorQueue := elevatorQueue union {next}; elevatorQueue := {y | y in set elevatorQueue & y <> nextFloor};

)elseif (next = <none>)then elevatorQueue := {y | y in set elevatorQueue & y <> nextFloor};return nextFloor;

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Achieved Improvements

Introduce classes for buttons and sensors Make use of mapping

Make elevator more intelligent Keep track of direction Choose next floor based on direction and distance

Introduce automatic test Read test sequence from file

Make sure the VIP receives special treatment No neighbours in elevator when VIP wants to use it Execute VIP order as soon as possible

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VDMUnit