llstatemachine.h

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#ifndef LL_LLSTATEMACHINE_H
#define LL_LLSTATEMACHINE_H

#include <string>

#include "llerror.h"
#include <map>

class LLUniqueID
{
        friend bool     operator==(const LLUniqueID &a, const LLUniqueID &b);
        friend bool     operator!=(const LLUniqueID &a, const LLUniqueID &b);
protected:
        static U32      sNextID;
        U32                     mId;
public:
        LLUniqueID(){mId = sNextID++;}
        virtual ~LLUniqueID(){}
        U32             getID() {return mId;}
};

class LLFSMTransition : public LLUniqueID
{
public:
        LLFSMTransition() : LLUniqueID(){};
        virtual std::string getName()const { return "unnamed"; }
};

class LLFSMState : public LLUniqueID
{
public:
        LLFSMState() : LLUniqueID(){};
        virtual void onEntry(void *){};
        virtual void onExit(void *){};
        virtual void execute(void *){};
        virtual std::string getName() const { return "unnamed"; }
};

class LLStateDiagram
{
typedef std::map<LLFSMTransition*, LLFSMState*> Transitions;

friend std::ostream& operator<<(std::ostream &s, LLStateDiagram &FSM);
friend class LLStateMachine;

protected:
        typedef std::map<LLFSMState*, Transitions> StateMap;
        StateMap                        mStates;
        Transitions                     mDefaultTransitions;
        LLFSMState*                     mDefaultState;
        BOOL                            mUseDefaultState;

public:
        LLStateDiagram();
        virtual ~LLStateDiagram();

protected:
        // add a state to the state graph, executed implicitly when adding transitions
        BOOL addState(LLFSMState *state);

        // add a directed transition between 2 states
        BOOL addTransition(LLFSMState& start_state, LLFSMState& end_state, LLFSMTransition& transition);

        // add an undirected transition between 2 states
        BOOL addUndirectedTransition(LLFSMState& start_state, LLFSMState& end_state, LLFSMTransition& transition);

        // add a transition that is taken if none other exist
        void addDefaultTransition(LLFSMState& end_state, LLFSMTransition& transition);

        // process a possible transition, and get the resulting state
        LLFSMState* processTransition(LLFSMState& start_state, LLFSMTransition& transition);

        // add a transition that exists for every state
        void setDefaultState(LLFSMState& default_state);

        // return total number of states with no outgoing transitions
        S32 numDeadendStates();

        // does this state exist in the state diagram?
        BOOL stateIsValid(LLFSMState& state);

        // get a state pointer by ID
        LLFSMState* getState(U32 state_id);

public:
        // save the graph in a DOT file for rendering and visualization
        BOOL saveDotFile(const char* filename);
};

class LLStateMachine
{
protected:
        LLFSMState*                     mCurrentState;
        LLFSMState*                     mLastState;
        LLFSMTransition*        mLastTransition;
        LLStateDiagram*         mStateDiagram;

public:
        LLStateMachine();
        virtual ~LLStateMachine();

        // set state diagram
        void setStateDiagram(LLStateDiagram* diagram);

        // process this transition
        void processTransition(LLFSMTransition &transition, void* user_data);

        // returns current state
        LLFSMState*     getCurrentState() const;

        // execute current state
        void runCurrentState(void *data);

        // set state by state pointer
        BOOL setCurrentState(LLFSMState *initial_state, void* user_data, BOOL skip_entry = TRUE);

        // set state by unique ID
        BOOL setCurrentState(U32 state_id, void* user_data, BOOL skip_entry = TRUE);
};

#endif //_LL_LLSTATEMACHINE_H

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