[63c1f6] | 1 | /*
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| 2 | * Observer.hpp
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| 3 | *
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| 4 | * Created on: Jan 19, 2010
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| 5 | * Author: crueger
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| 6 | */
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| 7 |
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| 8 | #ifndef OBSERVER_HPP_
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| 9 | #define OBSERVER_HPP_
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| 10 |
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| 11 | #include <map>
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| 12 | #include <set>
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| 13 |
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| 14 | /**
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| 15 | * Basic structure for the observer pattern
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| 16 | *
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| 17 | * Observers register themselves with the observables to be notified when something changes.
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| 18 | * In the Observable code that changes attributes should be wrapped in
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| 19 | * START_OBSERVER ... END_OBSERVER blocks. If other methods are called that also contain
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| 20 | * Observation blocks from there, these functions wont trigger notifications. Only the end
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| 21 | * of the final observation block triggers the update of Observers.
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| 22 | *
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| 23 | * Each observerable can have sub-observables. When one of these sub-observables changes and
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| 24 | * notifies its observers the observable that contains them will also notify its observers.
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| 25 | * This passing on of updates is blocked, when the main-observable is in the process of
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| 26 | * updating many of its internal sub-observables. This means the update is not passed, if
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| 27 | * it is produced while the main-observable itself is within any Observation block.
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| 28 | */
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| 29 |
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| 30 | class Observable;
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| 31 |
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| 32 | class Observer
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| 33 | {
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[d5f216] | 34 | friend class Observable;
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[63c1f6] | 35 | public:
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| 36 | Observer();
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| 37 | virtual ~Observer();
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| 38 |
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[d5f216] | 39 | protected:
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[63c1f6] | 40 | virtual void update(Observable *publisher)=0;
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| 41 | virtual void subjectKilled(Observable *publisher)=0;
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| 42 | };
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| 43 |
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| 44 | class Observable : public Observer {
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| 45 | public:
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| 46 | Observable();
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| 47 | virtual ~Observable();
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| 48 |
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| 49 | virtual void signOn(Observer *target);
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| 50 | virtual void signOff(Observer *target);
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| 51 |
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[d5f216] | 52 | protected:
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[63c1f6] | 53 | virtual void update(Observable *publisher);
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| 54 | virtual void subjectKilled(Observable *publisher);
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| 55 |
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| 56 | virtual void notifyAll();
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| 57 | protected:
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[d5f216] | 58 | // Observer mechanism is done from a static central place
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[63c1f6] | 59 | /**
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| 60 | * Internal method.
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| 61 | * Do not call directly. Use START_OBSERVER macro instead
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| 62 | */
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| 63 | static void start_observer_internal(Observable *publisher);
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| 64 | /**
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| 65 | * Internal method.
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| 66 | * Do not call directly. Use FINISH_OBSERVER macro instead
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| 67 | */
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| 68 | static void finish_observer_internal(Observable *publisher);
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| 69 |
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| 70 | private:
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| 71 | static std::map<Observable*, int> depth;
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| 72 | static std::multimap<Observable*,Observer*> callTable;
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| 73 | static std::set<Observable*> busyObservables;
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| 74 | };
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| 75 |
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| 76 |
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| 77 |
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| 78 | #define START_OBSERVER Observable::start_observer_internal(this);do{do{}while(0)
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| 79 | #define FINISH_OBSERVER }while(0);Observable::finish_observer_internal(this)
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| 80 | #endif /* OBSERVER_HPP_ */
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