/// <summary>
/// Add an observer to the observer collection
/// </summary>
/// <param name="observer"></param>
public virtual void Register(ICollectionObserver <T> observer)
{
if (Observers.Contains(observer))
{
return;
}
Observers.Add(observer);
}
/// <summary>
/// Remove an observer from the observer collection
/// </summary>
/// <param name="observer"></param>
public virtual void Unregister(ICollectionObserver <T> observer)
{
if (!Observers.Contains(observer))
{
return;
}
Observers.Remove(observer);
}
private bool TryGetDisposable(ICollectionObserver <T> observer, out IDisposable disposable)
{
var index = observers.FindIndex(tuple => tuple.Item1 == observer);
if (0 > index)
{
disposable = Disposable.Empty;
return(false);
}
disposable = observers[index].Item2;
return(true);
}
private void RemoveObserver(ICollectionObserver <T> observer)
{
IDisposable disposable;
lock (gate)
{
var index = observers.FindIndex(tuple => tuple.Item1 == observer);
if (0 > index)
{
return;
}
disposable = observers[index].Item2;
observers.RemoveAt(index);
}
disposable.Dispose();
}
public IDisposable Subscribe(ICollectionObserver <T> observer)
{
if (null == observer)
{
throw new ArgumentNullException(nameof(observer));
}
IDisposable disposable;
lock (gate)
{
if (false == TryGetDisposable(observer, out disposable))
{
disposable = Disposable.Create(observer, RemoveObserver);
observers.Add(new Tuple <ICollectionObserver <T>, IDisposable>(observer, disposable));
}
}
return(disposable);
}
