stoplight.java

SMC takes a state machine stored in a .sm file and generates a State pattern in twelve programming l

        // Southern light.
        g2.setPaint(_lights[SOUTH][RED]);
        g2.fill(new Ellipse2D.Double((_positions[1].x + LAMP_SPACE),
                                     (_positions[2].y + LAMP_SPACE),
                                     LAMP_DIAMETER,
                                     LAMP_DIAMETER));
        g2.setPaint(_lights[SOUTH][YELLOW]);
        g2.fill(new Ellipse2D.Double((_positions[1].x + LAMP_SPACE),
                                     (_positions[2].y + (LAMP_SPACE * 2) + LAMP_DIAMETER),
                                     LAMP_DIAMETER,
                                     LAMP_DIAMETER));
        g2.setPaint(_lights[SOUTH][GREEN]);
        g2.fill(new Ellipse2D.Double((_positions[1].x + LAMP_SPACE),
                                     (_positions[2].y + (LAMP_SPACE * 3) + (LAMP_DIAMETER * 2)),
                                     LAMP_DIAMETER,
                                     LAMP_DIAMETER));

        // Western light.
        g2.setPaint(_lights[WEST][GREEN]);
        g2.fill(new Ellipse2D.Double((_positions[0].x + LAMP_SPACE),
                                     (_positions[1].y + LAMP_SPACE),
                                     LAMP_DIAMETER,
                                     LAMP_DIAMETER));
        g2.setPaint(_lights[WEST][YELLOW]);
        g2.fill(new Ellipse2D.Double((_positions[0].x + (LAMP_SPACE * 2) + LAMP_DIAMETER),
                                     (_positions[1].y + LAMP_SPACE),
                                     LAMP_DIAMETER,
                                     LAMP_DIAMETER));
        g2.setPaint(_lights[WEST][RED]);
        g2.fill(new Ellipse2D.Double((_positions[0].x + (LAMP_SPACE * 3) + (LAMP_DIAMETER * 2)),
                                     (_positions[1].y + LAMP_SPACE),
                                     LAMP_DIAMETER,
                                     LAMP_DIAMETER));
    }

    public void handleTimeout()
    {
        // Get rid of the current timer.
        _stoplightTimer = null;

        _fsm.Timeout();
        return;
    }

    //----------------------------------------
    // State Machine Actions
    //
    public void InitLights()
    {
        // The lights are initially all black.
        int i;
        int j;
        for (i = 0; i < 4; ++i)
        {
            for (j = 0; j < 3; ++j)
            {
                _lights[i][j] = Color.black;
            }
        }

        return;
    }

    public void TurnLight(String light, String color)
    {
        if (light.compareTo("EWLIGHT") == 0)
        {
            if (color.compareTo("RED") == 0)
            {
                _lights[EAST][GREEN] = Color.black;
                _lights[EAST][YELLOW] = Color.black;
                _lights[EAST][RED] = Color.red;
                _lights[WEST][GREEN] = Color.black;
                _lights[WEST][YELLOW] = Color.black;
                _lights[WEST][RED] = Color.red;
            }
            else if (color.compareTo("GREEN") == 0)
            {
                _lights[EAST][GREEN] = Color.green;
                _lights[EAST][YELLOW] = Color.black;
                _lights[EAST][RED] = Color.black;
                _lights[WEST][GREEN] = Color.green;
                _lights[WEST][YELLOW] = Color.black;
                _lights[WEST][RED] = Color.black;
            }
            else if (color.compareTo("YELLOW") == 0)
            {
                _lights[EAST][GREEN] = Color.black;
                _lights[EAST][YELLOW] = Color.yellow;
                _lights[EAST][RED] = Color.black;
                _lights[WEST][GREEN] = Color.black;
                _lights[WEST][YELLOW] = Color.yellow;
                _lights[WEST][RED] = Color.black;
            }
        }
        else if (light.compareTo("NSLIGHT") == 0)
        {
            if (color.compareTo("RED") == 0)
            {
                _lights[NORTH][GREEN] = Color.black;
                _lights[NORTH][YELLOW] = Color.black;
                _lights[NORTH][RED] = Color.red;
                _lights[SOUTH][GREEN] = Color.black;
                _lights[SOUTH][YELLOW] = Color.black;
                _lights[SOUTH][RED] = Color.red;
            }
            else if (color.compareTo("GREEN") == 0)
            {
                _lights[NORTH][GREEN] = Color.green;
                _lights[NORTH][YELLOW] = Color.black;
                _lights[NORTH][RED] = Color.black;
                _lights[SOUTH][GREEN] = Color.green;
                _lights[SOUTH][YELLOW] = Color.black;
                _lights[SOUTH][RED] = Color.black;
            }
            else if (color.compareTo("YELLOW") == 0)
            {
                _lights[NORTH][GREEN] = Color.black;
                _lights[NORTH][YELLOW] = Color.yellow;
                _lights[NORTH][RED] = Color.black;
                _lights[SOUTH][GREEN] = Color.black;
                _lights[SOUTH][YELLOW] = Color.yellow;
                _lights[SOUTH][RED] = Color.black;
            }
        }
        return;
    }

    public void InformCanvas(String greenlight)
    {
        // Tell the owning canvas that the light has changed.
        // Also tell the canvas if a light is now green.
        if (greenlight.compareTo("YELLOW") == 0)
        {
            _owner.lightChanged(TrafficCanvas.YELLOW_LIGHT);
        }
        else if (greenlight.compareTo("EastWest") == 0)
        {
            _owner.lightChanged(TrafficCanvas.EW_LIGHT);
        }
        else
        {
            _owner.lightChanged(TrafficCanvas.NS_LIGHT);
        }

        return;
    }

    public void SetTimer(String direction)
    {
        int duration;

        if (direction.compareTo("NorthSouth") == 0)
        {
            duration = _nsLightDuration;
        }
        else if (direction.compareTo("EastWest") == 0)
        {
            duration = _ewLightDuration;
        }
        else
        {
            duration = _yellowDuration;
        }

        SetTimer(duration);

        return;
    }

    public void SetTimer(int duration)
    {
        // Remember when this timer was set and how long it
        // lasts. This information is needed for pausing and
        // continuing.
        _timerStart = new java.util.Date();
        _timerDuration = duration;

        // If the timer already exists, then get rid of it.
        if (_stoplightTimer != null)
        {
            // If the timer is running, then stop it, reset
            // its timeout value and run it again.
            if (_stoplightTimer.isRunning() == true)
            {
                _stoplightTimer.stop();
            }

            _stoplightTimer = null;
        }

        _stoplightTimer = new Timer(_timerDuration,
                                    new StoplightTimeoutListener(this));
        _stoplightTimer.setRepeats(false);
        _stoplightTimer.start();

        return;
    }

    public void PauseTimer()
    {
        // Figure out how much time is left on the timer and
        // use that value when continuing the timer.
        java.util.Date currTime = new java.util.Date();

        // Stop the timer now and do the calculations after.
        if (_stoplightTimer != null &&
            _stoplightTimer.isRunning() == true)
        {
            _stoplightTimer.stop();
        }

        _timerDuration = _timerDuration -
                (int) (currTime.getTime() - _timerStart.getTime());
        if (_timerDuration < 0)
        {
            _timerDuration = 0;
        }
        _timerStart = null;

        return;
    }

    public void ContinueTimer()
    {
        // Pick up where we left off by restarting the timer.
        SetTimer(_timerDuration);

        return;
    }

    public void StopTimer()
    {
        // Stop the timer and clear the timer data.
        if (_stoplightTimer != null &&
            _stoplightTimer.isRunning() == true)
        {
            _stoplightTimer.stop();
        }
        _stoplightTimer = null;
        _timerDuration = 0;
        _timerStart = null;

        return;
    }

// Member data.

    //----------------------------------------
    // Dynamic data.
    //
    // private StoplightContext _fsm;
    private Point[] _positions;
    private Dimension _size;
    private TrafficCanvas _owner;
    private StoplightContext _fsm;

    // Keep track of each light's current color.
    private Color[][] _lights;

    // Remember when the timer was started and how long the
    // timer is running.
    private java.util.Date _timerStart;
    private int _timerDuration;
    private Timer _stoplightTimer;

    // Stop light timing.
    private int _nsLightDuration;
    private int _ewLightDuration;
    private int _yellowDuration;

    //----------------------------------------
    // Static data.
    //
    public static final int NORTH = 0;
    public static final int EAST = 1;
    public static final int SOUTH = 2;
    public static final int WEST = 3;

    private static final int LAMP_DIAMETER = 6;
    private static final int LAMP_SPACE = 3;
    private static final int GREEN = 0;
    private static final int YELLOW = 1;
    private static final int RED = 2;


    //----------------------------------------
    // Nested classes.
    //
    private final class StoplightTimeoutListener
        implements ActionListener
    {
        public StoplightTimeoutListener(Stoplight owner)
        {
            _owner = owner;
        }

        public void actionPerformed(ActionEvent e)
        {
            _owner.handleTimeout();
            return;
        }

        private Stoplight _owner;
    }
}