#ifndef LEMON_SIMANN_H

 #define LEMON_SIMANN_H

 namespace lemon {

   const double INFTY = 1e24;

   class SimAnnBase {

   public:

     class Controller;

   private:

     Controller *controller;

   protected:

     double curr_cost;

     double prev_cost;

     double best_cost;

     virtual void mutate() = 0;

     virtual void revert() = 0;

     virtual void saveAsBest() = 0;

   public:

     SimAnnBase() {

       curr_cost = prev_cost = best_cost = INFTY;

     }

     void setController(Controller &_controller) { controller = &_controller; }

     double getBestCost() { return best_cost; }

     void run() {

       while (controller->next()) {

         mutate();

         if (controller->accept(prev_cost - curr_cost)) {

           controller->acceptEvent();

           if (curr_cost < best_cost) {

             saveAsBest();

             controller->improveEvent();

           }

         }

         else {

           revert();

           controller->rejectEvent();

         }

       }

     }

     class Controller {

     public:

       virtual void acceptEvent() {}

       virtual void improveEvent() {}

       virtual void rejectEvent() {}

       virtual bool next() = 0;

       virtual bool accept(double cost_diff) = 0;

     };

   };

   template <typename E>

   class SimAnn : public SimAnnBase {

   private:

     E *curr_ent;

     E *prev_ent;

     E *best_ent;

   public:

     SimAnn() : SimAnnBase() {}

     void setEntity(E &Ent) {

       curr_ent = new E(Ent);

       prev_ent = new E(Ent);

       best_ent = new E(Ent);

     }

     E getBestEntity() { return *best_ent; }

     void mutate() {

       *prev_ent = *curr_ent;

       prev_cost = curr_cost;

       curr_cost = curr_ent->mutate();

     }

     void revert() {

       E *tmp = curr_ent;

       curr_ent = prev_ent;

       prev_ent = tmp;

       curr_cost = prev_cost;

     }

     void saveAsBest() {

       *best_ent = *curr_ent;

       best_cost = curr_cost;

     }

   };

   class EntitySkeleton {

   public:

     // returns the new cost

     double mutate() { return 0.0; }

   };

   template <typename E>

   class SimAnn2 : public SimAnnBase {

   private:

     E *curr_ent;

     E *best_ent;

   public:

     SimAnn2() : SimAnnBase() {}

     void setEntity(E &Ent) {

       curr_ent = new E(Ent);

       best_ent = new E(Ent);

     }

     E getBestEntity() { return *best_ent; }

     void mutate() {

       curr_ent->mutate();

     }

     void revert() {

       curr_ent->revert();

     }

     void saveAsBest() {

       *best_ent = *curr_ent;

       best_cost = curr_cost;

     }

   };

   class EntitySkeleton2 {

   public:

     // returns the new cost

     double mutate() { return 0.0; }

     // restores the entity to its previous state i.e. reverts the effects of

     // the last mutate()

     void revert() {}

   };

 }

 #endif