Question

我在NuSMV中写了两个模块，但是我收到了错误，＆＃34;案例条件并非详尽无遗＆＃34;此错误指向代码中的最后一个case语句。我不知道如何解决这个问题，因为我目前拥有的案例是变量所需的唯一案例。第一个模块＆＃34; train＆＃34;实例化两次，以便两列火车可以在一条轨道上。模块＆＃34;控制器＆＃34;充当控制器，接收来自两列火车的输入并防止它们同时在桥上。

以下是代码：

MODULE main
VAR
  trainE : Train(controller1.signalE);
  trainW : Train(controller1.signalW);
  controller1 : controller(trainE.out, trainW.out);

  INVARSPEC(!(trainE.mode = bridge & trainW.mode = bridge))
MODULE Train(signal)
    VAR 
    mode: {away, wait, bridge};
    out: {None, arrive, leave};
    ASSIGN
        init(mode) := away;
        init(out) := None;

        --Task A1
        next(out)  := case
                    mode = away: arrive;
                    mode = bridge: leave;
                    TRUE: None;
        esac;

        --Task A2
        next(mode) := case
                    mode = away & next(out) = arrive: wait;
                    mode = bridge & next(out) = leave: away;
                    mode = wait & signal = green: bridge;
                    TRUE: mode;

        esac;

MODULE controller(outE, outW)
    VAR
        signalE: {green, red};
        signalW: {green, red};
        west: {green, red};
        east: {green, red};
        nearE: boolean;
        nearW: boolean;
    ASSIGN
        init(west):= red;
        init(east):= red;
        init(nearW):= FALSE;
        init(nearE):= FALSE;

        --Task A1
        next(signalW):= west;

        --Task A2
        next(signalE):= east;

        --Task A3
        next(nearE):= case
                        outE = arrive: TRUE;
                        outE = leave: FALSE;
                        esac;
        next(nearW):= case
                        outW = arrive: TRUE;
                        outW = leave: FALSE;
                        esac;
        next(east):= case
                        next(nearE) = FALSE: red;
                        west = red: green;
                        esac;
        next(west):= case
                        next(nearW) = FALSE: red;
                        east = red: green;
                        esac;

Answer 1

您在所有case条件中实际上都有相同的错误：

file test.smv: line 68: case conditions are not exhaustive
file test.smv: line 64: case conditions are not exhaustive
file test.smv: line 60: case conditions are not exhaustive
file test.smv: line 56: case conditions are not exhaustive

让我们考虑第56行的错误。您写了以下案例：

next(nearE) := case
    outE = arrive : TRUE;
    outE = leave  : FALSE;
esac;

现在，outE是与trainE.out相关联的输入。在模块Train内，out被声明为一个变量，可以包含 3个可能的值：{None, arrive, leave}。但是，在您的代码中，仅为两个可能的nearE 的当前值指定outE的未来值。因此， NuSMV 正确地抱怨，因为在当前状态nearE等于{{1}时，它不知道在下一个状态下应该为outE分配什么值}。

因此，为了解决此错误，您应该考虑在None时想要发生什么，并将该规范添加到模型中。

如果您不希望outE = None的值发生变化，通常的设计做法是添加捕获所有案例条件，如下所示：

nearE

案件情况并非详尽无遗？

1 个答案: