smcvbgenerator.java

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

            _source.println();
            _source.print(_indent);
            _source.println(
                "    '------------------------------------------------------------");
            _source.print(_indent);
            _source.println("    ' Shared data");
            _source.print(_indent);
            _source.println("    '");
            _source.println();
            _source.print(_indent);
            _source.print("    ");
            _source.println(
                "Private Shared _transitions As IDictionary");
            _source.println();
            _source.print(_indent);
            _source.println("    Shared Sub New()");
            _source.println();
            _source.print(_indent);
            _source.print("        ");
            _source.println("_transitions = New Hashtable()");

            // Now place the transition names into the list.
            for (SmcTransition transition: allTransitions)
            {
                transName = transition.getName();

                // If the transition is in this state, then its
                // value is 1.
                if (stateTransitions.contains(
                        transition) == true)
                {
                    transDefinition = 1;
                }
                // If the transition is defined in this map's
                // default state, then the value is 2.
                else if (defaultTransitions.contains(
                             transition) == true)
                {
                    transDefinition = 2;
                }
                // Otherwise the value is 0 - undefined.
                else
                {
                    transDefinition = 0;
                }

                _source.print(_indent);
                _source.print("        ");
                _source.print("_transitions.Add(\"");
                _source.print(transName);
                _source.print("\", ");
                _source.print(transDefinition);
                _source.println(")");
            }

            _source.println();
            _source.print(_indent);
            _source.println("    End Sub");
        }

        _source.print(_indent);
        _source.println("End Class");

        return;
    } // end of visit(SmcState)

    public void visit(SmcTransition transition)
    {
        SmcState state = transition.getState();
        SmcMap map = state.getMap();
        String context = map.getFSM().getContext();
        String mapName = map.getName();
        String stateName = state.getClassName();
        String transName = transition.getName();
        List<SmcParameter> parameters =
            transition.getParameters();
        List<SmcGuard> guards = transition.getGuards();
        boolean nullCondition = false;
        Iterator<SmcParameter> pit;
        Iterator<SmcGuard> git;
        SmcGuard guard;

        _source.println();
        _source.print(_indent);
        _source.print("    Public Overrides Sub ");

        // If this is the Default transition, then change its
        // name to "Default_" because Default is a VB keyword.
        if (transName.equals("Default") == true)
        {
            _source.print("Default_");
        }
        else
        {
            _source.print(transName);
        }

        _source.print("(ByRef context As ");
        _source.print(context);
        _source.print("Context");

        // Add user-defined parameters.
        for (SmcParameter param: parameters)
        {
            _source.print(", ");
            param.accept(this);
        }
        _source.println(")");
        _source.println();

        // Generate the ctxt local variable if needed.
        if (transition.hasCtxtReference() == true)
        {
            _source.print(_indent);
            _source.print("        Dim ctxt As ");
            _source.print(context);
            _source.println(" = context.Owner");
        }

        // Generate the loopbackFlag for the Default state only
        // and only if at least one of the guards references a
        // non-nil end state.
        if (stateName.equals("Default") == true &&
            transition.hasNonNilEndState() == true)
        {
            _source.print(_indent);
            _source.println(
                "        Dim loopbackFlag As Boolean = False");
            _source.println();
        }

        // Output transition to debug stream.
        if (Smc.isDebug() == true)
        {
            String sep;

            _source.println("#If TRACE Then");
            _source.print(_indent);
            _source.println("        Trace.WriteLine( _");
            _source.print(_indent);
            _source.print("            \"TRANSITION   : ");
            _source.print(mapName);
            _source.print(".");
            _source.print(stateName);
            _source.print(".");
            _source.print(transName);

            _source.print("(");
            for (pit = parameters.iterator(), sep = "";
                 pit.hasNext() == true;
                 sep = ", ")
            {
                _source.print(sep);
                (pit.next()).accept(this);
            }
            _source.print(")");

            _source.println("\")");
            _source.println("#End If");
            _source.println();
        }

        // Loop through the guards and print each one.
        for (git = guards.iterator(),
                 _guardIndex = 0,
                 _guardCount = guards.size();
             git.hasNext() == true;
             ++_guardIndex)
        {
            guard = git.next();

            // Count up the guards with no condition.
            if (guard.getCondition().length() == 0)
            {
                nullCondition = true;
            }

            guard.accept(this);
        }

        // If all guards have a condition, then create a final
        // "else" clause which passes control to the default
        // transition. Pass all arguments into the default
        // transition.
        if (_guardIndex > 0 && nullCondition == false)
        {
            _source.println();
            _source.print(_indent);
            _source.println("        Else");
            _source.print(_indent);
            _source.print("            MyBase.");
            _source.print(transName);
            _source.print("(context");

            for (SmcParameter param: parameters)
            {
                _source.print(", ");
                _source.print(param.getName());
            }

            _source.println(")");
            _source.print(_indent);
            _source.println("        End If");
        }
        // Need to add a final newline after a multiguard block.
        else if (_guardCount > 1)
        {
            _source.print(_indent);
            _source.println("        End If");
            _source.println();
        }

        _source.print(_indent);
        _source.println("    End Sub");

        return;
    } // end of visit(SmcTransition)

    public void visit(SmcGuard guard)
    {
        SmcTransition transition = guard.getTransition();
        SmcState state = transition.getState();
        SmcMap map = state.getMap();
        String context = map.getFSM().getContext();
        String mapName = map.getName();
        String stateName = state.getClassName();
        int transType = guard.getTransType();
        boolean defaultFlag =
            stateName.equalsIgnoreCase("Default");
        boolean loopbackFlag = false;
        String indent1;
        String indent2;
        String indent3;
        String indent4;
        String endStateName = guard.getEndState();
        String fqEndStateName = "";
        String pushStateName = guard.getPushState();
        String condition = guard.getCondition();
        List<SmcAction> actions = guard.getActions();

        // If this guard's end state is not of the form
        // "map::state", then prepend the map name to the
        // state name.
        // DON'T DO THIS IF THIS IS A POP TRANSITION!
        // The "state" is actually a transition name.
        if (transType != Smc.TRANS_POP &&
            endStateName.length () > 0 &&
            endStateName.equals(NIL_STATE) == false)
        {
            endStateName = scopeStateName(endStateName, mapName);
        }

        stateName = scopeStateName(stateName, mapName);
        pushStateName = scopeStateName(pushStateName, mapName);

        loopbackFlag =
            isLoopback(transType, stateName, endStateName);

        // The guard code generation is a bit tricky. The first
        // question is how many guards are there? If there are
        // more than one, then we will need to generate the
        // proper "if-then-else" code.
        if (_guardCount > 1)
        {
            indent1 = _indent + "            ";

            // There are multiple guards.
            // Is this the first guard?
            if (_guardIndex == 0 && condition.length() > 0)
            {
                // Yes, this is the first. This means an "if"
                // should be used.
                _source.print(_indent);
                _source.print("        If ");
                _source.print(condition);
                _source.println(" _");
                _source.print(_indent);
                _source.println("        Then");
            }
            else if (condition.length() > 0)
            {
                // No, this is not the first transition but it
                // does have a condition. Use an "else if".
                _source.println();
                _source.print(_indent);
                _source.print("        ElseIf ");
                _source.print(condition);
                _source.println(" _");
                _source.print(_indent);
                _source.println("        Then");
            }
            else
            {
                // This is not the first transition and it has
                // no condition.
                _source.println();
                _source.print(_indent);
                _source.println("        Else");
            }
        }
        else
        {
            // There is only one guard. Does this guard have
            // a condition?
            if (condition.length() == 0)
            {
                // No. This is a plain, old. vanilla transition.
                indent1 = _indent + "        ";
            }
            else
            {
                // Yes there is a condition.
                indent1 = _indent + "            ";
                _source.print(_indent);
                _source.print("        If ");
                _source.print(condition);
                _source.println(" _");
                _source.print(_indent);
                _source.println("        Then");
            }
        }

        // Now that the necessary conditions are in place, it's
        // time to dump out the transition's actions. First, do
        // the proper handling of the state change. If this
        // transition has no actions, then set the end state
        // immediately. Otherwise, unset the current state so
        // that if an action tries to issue a transition, it will
        // fail.
        if (actions.size() == 0)
        {
            fqEndStateName = endStateName;
        }
        // Save away the current state if this is a loopback
        // transition. Storing current state allows the
        // current state to be cleared before any actions are
        // executed. Remember: actions are not allowed to
        // issue transitions and clearing the current state
        // prevents them from doing do.
        else if (loopbackFlag == true)
        {
            fqEndStateName = "endState";
            _source.print(_indent);
            _source.print("Dim ");
            _source.print(fqEndStateName);
            _source.print(" As ");
            _source.print(context);
            _source.println("State = context.State");
            _source.println();
        }
        else
        {
            fqEndStateName = endStateName;
        }

        // Decide if runtime loopback checking must be done.
        if (defaultFlag == true &&
            transType != Smc.TRANS_POP &&
            loopbackFlag == false)
        {
            _source.print(indent1);
            _source.print("If context.State.Name = ");
            _source.print(fqEndStateName);
            _source.println(".Name _");
            _source.print(indent1);
            _source.println("Then");
            _source.print(indent1);
            _source.println("    loopbackFlag = True");