Observer.h

/*
 *  Copyright (C) 2005-2018 Team Kodi
 *  This file is part of Kodi - https://kodi.tv
 *
 *  SPDX-License-Identifier: GPL-2.0-or-later
 *  See LICENSES/README.md for more information.
 */

#pragma once

#include "threads/CriticalSection.h"

#include <atomic>
#include <vector>

class Observable;
class ObservableMessageJob;

typedef enum
{
  ObservableMessageNone,
  ObservableMessagePeripheralsChanged,
  ObservableMessageSettingsChanged,
  ObservableMessageButtonMapsChanged,
  // Used for example when the subtitle alignment position change
  ObservableMessagePositionChanged,
  ObservableMessageGamePortsChanged,
  ObservableMessageGameAgentsChanged,
} ObservableMessage;

class Observer
{
public:
  Observer() = default;
  virtual ~Observer() = default;
  virtual void Notify(const Observable &obs, const ObservableMessage msg) = 0;
};

class Observable
{
  friend class ObservableMessageJob;

public:
  Observable() = default;
  virtual ~Observable() = default;
  virtual Observable &operator=(const Observable &observable);

  virtual void RegisterObserver(Observer *obs);

  virtual void UnregisterObserver(Observer *obs);

  virtual void NotifyObservers(const ObservableMessage message = ObservableMessageNone);

  virtual void SetChanged(bool bSetTo = true);

  virtual bool IsObserving(const Observer &obs) const;

protected:
  void SendMessage(const ObservableMessage message);

  std::atomic<bool>       m_bObservableChanged{false}; 
  std::vector<Observer *> m_observers;                 
  mutable CCriticalSection m_obsCritSection; 
};