FSMBase.c

Go to the documentation of this file.

void fsmbDebugPrint (string s)
{
    //Print("" + s); // comment/uncomment to hide/see debug logs
}
void fsmbDebugSpam (string s)
{
    //Print("" + s); // comment/uncomment to hide/see debug spam
}
 
 
class FSMTransition<Class FSMStateBase, Class FSMEventBase, Class FSMActionBase, Class FSMGuardBase>
{
    ref FSMStateBase m_srcState;
    ref FSMEventBase m_event; // @NOTE: NULL event means "completion transition" in UML speak
    ref FSMStateBase m_dstState; // @NOTE: NULL dst state == UML terminate pseudonode
    ref FSMActionBase m_action;
    ref FSMGuardBase m_guard;
 
    void FSMTransition (FSMStateBase src, FSMEventBase e, FSMStateBase dst, FSMActionBase a = NULL, FSMGuardBase g = NULL)
    {
        m_srcState = src;
        m_event = e;
        m_dstState = dst;
        m_action = a;
        m_guard = g;
    }
};
 
enum ProcessEventResult
{
    FSM_OK,
    FSM_TERMINATED,
    FSM_ABORTED,
    FSM_NO_TRANSITION,
};
 
class FSMBase<Class FSMStateBase, Class FSMEventBase, Class FSMActionBase, Class FSMGuardBase>
{
    protected ref FSMStateBase m_state; 
    protected ref FSMStateBase m_initialState; 
    protected ref FSMEventBase m_initialEvent; 
    protected ref array<ref FSMTransition<FSMStateBase, FSMEventBase, FSMActionBase, FSMGuardBase>> m_transitions; 
 
    void FSMBase ()
    {
        m_transitions = new array<ref FSMTransition<FSMStateBase, FSMEventBase, FSMActionBase, FSMGuardBase>>;
    }
 
    FSMStateBase GetCurrentState ()
    {
        return m_state;
    }
 
    void SetInitialState (FSMStateBase initial_state)
    {
        m_initialState = initial_state;
    }
 
    void Start (FSMEventBase initial_event = NULL)
    {
        fsmbDebugPrint("[fsm] " + this.ToString() + "::Start(" + initial_event.ToString() + "), init_state=" + m_initialState.ToString());
 
        m_state = m_initialState;
        m_state.OnEntry(initial_event);
    }
 
    bool IsRunning () { return m_state != NULL; }
 
    void Terminate (FSMEventBase terminal_event = NULL)
    {
        if (IsRunning())
        {
            m_state.OnExit(terminal_event);
            m_state = NULL;
        }
    }
 
    void Update (float dt)
    {
        if (IsRunning())
            m_state.OnUpdate(dt);
    }
    
    void AddTransition (FSMTransition<FSMStateBase, FSMEventBase, FSMActionBase, FSMGuardBase> t)
    {
        m_transitions.Insert(t);
    }
 
    ProcessEventResult ProcessEvent (FSMEventBase e)
    {
        FSMStateBase curr_state = m_state;
 
        int count = m_transitions.Count();
        for (int i = 0; i < count; ++i)
        {
            FSMTransition<FSMStateBase, FSMEventBase, FSMActionBase, FSMGuardBase> row = m_transitions.Get(i);
            if (row.m_srcState.Type() == curr_state.Type() && row.m_event.Type() == e.Type())
            {
                FSMTransition<FSMStateBase, FSMEventBase, FSMActionBase, FSMGuardBase> t = m_transitions.Get(i);
                bool hasGuard = t.m_guard != NULL;
                if (!hasGuard || (hasGuard && t.m_guard.GuardCondition(e)))     // 1) exec guard (if any)
                {
                    ProcessLocalTransition(t, e); // 2) process transition allowed by guard
                }
            }
        }
        return ProcessEventResult.FSM_NO_TRANSITION;
    }
 
    protected ProcessEventResult ProcessLocalTransition (FSMTransition<FSMStateBase, FSMEventBase, FSMActionBase, FSMGuardBase> t, FSMEventBase e)
    {
        fsmbDebugPrint("[fsm] (local) state=" + t.m_srcState.ToString() + "-------- event=" + e.ToString() + "[G=" + t.m_guard.ToString() +"]/A=" + t.m_action.ToString() + " --------|> dst=" + t.m_dstState.ToString());
 
        m_state.OnExit(e);          // 1) call onExit on old state
 
        if (t.m_action)
            t.m_action.Action(e);   // 2) execute transition action (if any)
 
        m_state = t.m_dstState;     // 3) change state to new
 
        if (t.m_dstState != NULL)
        {
            m_state.OnEntry(e);     // 4a) call onEntry on new state
            return ProcessEventResult.FSM_OK;
        }
        else
        {
            fsmbDebugPrint("[fsm] terminating fsm: state=" + t.m_srcState.ToString() + " event=" + e.ToString());
            return ProcessEventResult.FSM_TERMINATED; // 4b) or terminate
        }
    }
};