--- /dev/null
+#ifndef __DISPATCHER_HXX__
+#define __DISPATCHER_HXX__
+
+#include <set>
+#include <string>
+#include <map>
+
+namespace YACS
+{
+ namespace ENGINE
+ {
+ class Node;
+ class Executor;
+
+/*! \brief Base class for observer in observer pattern
+ *
+ * When an event occurs, a registered observer is notified by
+ * calling its notifyObserver method with 2 arguments : the object
+ * which has emitted the event and the event type. There is no more
+ * data. It's the responsability of the observer to request all needed
+ * information from the emitting object.
+ *
+ */
+ class Observer
+ {
+ public:
+ virtual void notifyObserver(Node* object,const std::string& event);
+ virtual ~Observer();
+ };
+
+/*! \brief Base class for dispatcher in observer pattern
+ *
+ * Dispatcher and Observer objects can be used to be notified about events
+ * that occurs in editing or executing a calculation schema.
+ *
+ * When an object wants to notify an event, it calls the dispatch method
+ * of the dispatcher with 2 arguments : the object reference and an event type.
+ * The dispatcher which is a singleton is obtained by calling the class method
+ * getDispatcher.
+ * The dispatcher notifies all the registered observers by calling their notifyObserver
+ * method.
+ *
+ * Observers can be registered by calling the addObserver method with two
+ * arguments : an object reference and an event type. This observer will be
+ * notify with events coming only from this object.
+ *
+ * Limitation : emitting objects can be only Node
+ *
+ */
+ class Dispatcher
+ {
+ public:
+ virtual void dispatch(Node* object,const std::string& event);
+ virtual void addObserver(Observer* observer,Node* object,const std::string& event);
+ virtual void removeObserver(Observer* observer,Node* object,const std::string& event);
+ virtual void printObservers();
+ static Dispatcher* getDispatcher();
+ static void setDispatcher(Dispatcher* dispatcher);
+ virtual ~Dispatcher();
+ protected:
+ std::map< std::pair<Node*,std::string> , std::set<Observer*> > _observers;
+ std::map< std::pair<Executor*,std::string> , std::set<Observer*> > _observExec;
+ static Dispatcher* _singleton;
+ };
+
+ }
+}
+
+#endif
