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对于一个项目，我目前正在尝试为想象中的飞机编写一个小型飞行员辅助系统。任务是学习 Ada Spark，而不是航空电子设备。我已经对我希望使用的飞机组件进行了建模，在主文件中进行了一些测试以检查组件是否按预期工作，一切都很好，现在我要在函数中添加前置条件和后置条件以确保我的飞机是超级的安全的。一种这样的安全措施是确保在飞机被拖曳时不能打开发动机，反之亦然，在发动机打开时切换到拖曳。

我将引擎建模为高度复杂的记录，具有一个属性，类型 OnOff，它采用值 On 或 Off 之一。注意我计划扩展属性，所以它不会保留一个属性记录。

这是引擎规范文件

package engines with SPARK_Mode
is

type OnOff is (On, Off);
type Engine is record
  isOn: OnOff;
end record;


procedure switchOn (x : in out Engine);
procedure switchOff (x : in out Engine);

end engines;

我的飞机是这样组装的：

   type Plane is record
     engine1: Engine;
     engine2: Engine;
     gearOfLanding: LandingGear;
     doorPax1, doorPax2, doorServ1, doorServ2, 
     doorCockpit: Door;
     panelOfReadings: ReadingsPanel;
     panelOfAlerts: AlertsPanel;
     planOfFlight: FlightPlan;
     speedLimits: SpeedLimit;
     altitudeLimits: AltitudeLimit;
     attitudeLimits: AttitudeLimit; 
     litresPerMile: Integer;
     fuelTank1: FuelTank;
  end record;

planes 文件中的过程 switchOnEngine 将引擎作为输入，并从引擎文件中调用 switchOn。这是规格，下面是正文：

  procedure switchOnEngine (x : in out Engine; y : in Plane) with
    Pre => y.panelOfReadings.mode /= Tow,
    Post => x = (isOn => On) and y.panelOfReadings.mode /= Tow;



  procedure switchOnEngine (x : in out Engine; y : in Plane)
  is
  begin
      switchOn(x);
  
  end switchOnEngine;

飞机作为变量传入，因此我可以检查我的前后条件的各种属性，但我收到警告消息，我不确定如何解决。

precondition might fail
cannot prove y.panelOfReadings.mode /= Tow e.g when .......mode =>Tow

以下行也从我控制我的飞机的主文件中给出错误

switchOnEngine(AirForceOne.engine1, AirForceOne);

formal parameters x and y are aliased, and this is being marked as a 'high' priority warning.

这是主文件中飞机的初始化

AirForceOne : Plane := (
   engine1 => (isOn => Off),
   engine2 => (isOn => Off),
   litresPerMile => 5,
   gearOfLanding => (isExtended => Extended),
   doorPax1 => (isClosed => Closed, isLocked => Unlocked),
   doorPax2 => (isClosed => Closed, isLocked => Unlocked),
   doorServ1 => (isClosed => Closed, isLocked => Unlocked),
   doorServ2  => (isClosed => Closed, isLocked => Unlocked),
   doorCockpit => (isClosed => Closed, isLocked => Unlocked),
   fuelTank1 => (capacity=>26000, currentFuel=>26000),
   planOfFlight => (distFromDest => 1500),
   panelOfReadings =>
       (mode => Tow,
        currentSpeed => 0,
        altitud => 0,
        attitud =>
            (currentPitch=>0,
             currentRoll =>0)
       ),
   panelOfAlerts =>
       (approachingStallSpeed => Off,
        unRestrictedSpeed => Off,
        withinLandingSpdRange => Off,
        withinOptCruiseAlt => Off,
        withinOptCruiseSpeed => Off,
        takeoffSpeedReached => Off,
        fuelStatus => Off,
        maxPitchAngleExceeded => Off,
        maxRollAngleExceeded => Off),
   speedLimits =>
       (minLanding => 180,
        maxLanding => 200,
        minStall => 110,
        minTakeoff => 130,
        maxRestricted => 300,
        maxGroundMode => 10),
   altitudeLimits =>
       (minFlight => 500,
        maxFlight => 41000,
        optCruiseAlt => 36000,
        maxRestrictedSpeed => 10000,
        maxInitiateFlareMode => 100),
   attitudeLimits =>
       (maxRoll => 30,
        maxPitch => 30,
        minRoll => -30,
        minPitch => -30)
 );

任何帮助都会很棒。我认为在飞机不能被拖曳的前提下建议就足够了，但似乎还不够。

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1 回答 1

3

的目的Switchonengine是改变飞机的状态。编写它来改变引擎的状态会使事情复杂化。

Max_Engines : constant := 100; -- The Lillium jet has 36, so I hope this is enough

type Engine_Num is range 1 .. Max_Engines;

type Engine_Info is ...

type Engine_Map is array (Engine_Num range <>) of Engine_Info with
   Dynamic_Predicate => Engine_Map'First = 1;

type Plane_Info (Num_Engines : Engine_Num) is record
   Engine : Engine_Map (1 .. Num_Engines);
   ...

procedure Turn_On (Engine : in Engine_Num; Plane : in out Plane_Info) with
   Pre => Engine in 1 .. Plane.Num_Engines and then
          (not Running (Plane.Engine (Engine) ) and not Under_Tow (Plane),
   Post => Running (Plane.Engine (Engine) );

Air_Force_One : Plane_Info (Num_Engines => 4);
于 2021-04-20T09:42:13.757 回答