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// SPDX-License-Identifier: LGPL-3.0-or-later
// Author: Kristian Lytje
#pragma once
#include <utility/observer_ptr.h>
#include <utility/Observer.h>
#include <list>
#include <memory>
namespace ausaxs::utility {
namespace detail {
template<typename T> concept observer_type = requires(T t, const T& value) {
{ t.notify(value) } -> std::same_as<void>;
};
}
template<typename T>
class Observable {
public:
Observable() = default;
~Observable() {
for (auto& o : observers) {
o->on_delete();
o->on_delete = [] () {}; // clear the on_delete callback to avoid dangling pointer to this
}
}
/**
* @brief Notify all observers of a new value.
*/
void notify(const T& value) {
for (auto& o : observers) {
o->notify(value);
}
}
/**
* @brief Create a new observer and attach it to this observable.
*
* When the returned observer is destroyed, it will detach itself from this observable.
*/
std::unique_ptr<Observer<T>> make_observer() {
auto o = std::make_unique<Observer<T>>();
o->on_delete = [this, ptr=o.get()] () {
this->detach_observer(ptr);
};
this->attach_observer(o.get());
return o;
}
private:
void attach_observer(observer_ptr<Observer<T>> observer) {
observers.push_back(observer);
}
void detach_observer(observer_ptr<Observer<T>> observer) {
observers.remove(observer);
}
std::list<observer_ptr<Observer<T>>> observers;
};
}
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