observable_value.hpp

// Copyright 2020 Pokitec
// All rights reserved.
 
#pragma once
 
#include "observable_base.hpp"
 
namespace tt::detail {
 
template<typename T>
class observable_value final : public observable_base<T> {
private:
    T value;
 
public:
    observable_value() noexcept :
        observable_base<T>(), value() {}
 
    observable_value(T const &value) noexcept :
        observable_base<T>(), value(value) {}
 
    virtual T load() const noexcept override {
        ttlet lock = std::scoped_lock(observable_base<T>::mutex);
        return value;
    }
 
    virtual bool store(T const &new_value) noexcept override {
        observable_base<T>::mutex.lock();
 
        ttlet old_value = value;
        if (new_value != old_value) {
            value = new_value;
            observable_base<T>::mutex.unlock();
            this->notify(old_value, new_value);
            return true;
        } else {
            observable_base<T>::mutex.unlock();
            return false;
        }
    }
};
 
}