observable_value.hpp

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#ifndef OBSERVABLE_VALUE_HPP
#define OBSERVABLE_VALUE_HPP
 
#include <memory>
#include <set>
 
#include "IObserver/IObserver.hpp"
 
template <typename TType>
class ObservableValue
{
private:
    TType                       _value;
    std::set<IObserver<TType>*> _subscriber;
 
    void notify() const
    {
        for (auto* observer : _subscriber)
        {
            if (observer)
                observer->update(_value);
        }
    }
 
public:
    ObservableValue() = default;
    ~ObservableValue()
    {
        while (!_subscriber.empty())
            unsubscribe(*_subscriber.begin());
    }
 
    ObservableValue(TType value)
    {
        _value = std::move(value);
    }
 
    ObservableValue& operator=(const TType& newValue)
    {
        if (newValue != _value)
            set(newValue);
 
        return *this;
    }
 
    void subscribe(IObserver<TType>* observer)
    {
        if (observer)
            _subscriber.insert(observer);
    }
 
    void unsubscribe(IObserver<TType>* observer)
    {
        if (observer)
            _subscriber.erase(observer);
    }
 
    void set(TType newValue)
    {
        if (newValue != _value)
        {
            _value = std::move(newValue);
            notify();
        }
    }
 
    int countSubscriber() const
    {
        return _subscriber.size();
    }
 
    const TType& get() const
    {
        return _value;
    }
};
#endif