Observer.h

#pragma once
 
#include "mc/_HeaderOutputPredefine.h"
#include "mc/deps/core/utility/Subject.h"
 
namespace Core {
 
template <class DerivedType, class LockType>
class Observer {
public:
    using SubjectType = ::Core::Subject<DerivedType, LockType>;
 
    SubjectType* mpSubject{};
 
public:
    Observer(Observer const&)               = delete;
    Observer&    operator=(Observer const&) = delete;
    SubjectType* getSubject() { return mpSubject; }
 
    Observer() = default;
    Observer(SubjectType& subject) : mpSubject(std::addressof(subject)) {}
 
    void removeFromSubject() {
        if (mpSubject) {
            mpSubject->removeObserver(*static_cast<DerivedType*>(this));
        }
    }
 
    virtual ~Observer() { removeFromSubject(); }
 
    virtual void _onSubjectDestroyed() {}
};
 
template <class ObserverType, class LockType>
Subject<ObserverType, LockType>::~Subject() {
    std::lock_guard<LockType> l{getLock()};
    for (auto& observer : mObservers) {
        observer->mpSubject = nullptr;
        observer->_onSubjectDestroyed();
    }
}
 
} // namespace Core