// if the listener object is reclaimed you may stop receiving messages because
// the handler may then also be GCed, so the caller is responsible for keeping it alive
private void AddListener <T>(out MessageListener <T> listener, MessageHandler <T> handler, object key, bool keyIsWeak)
{
if (handler == null)
{
throw new ArgumentNullException("handler");
}
List <HandlerEntry> entries;
int? keyHash = null;
WeakReference weakKey = null;
if (key == null)
{
if (!untargeted.TryGetValue(typeof(T), out entries))
{
entries = new List <HandlerEntry>();
untargeted.Add(typeof(T), entries);
}
}
else
{
Dictionary <int, List <HandlerEntry> > entryLists;
if (!targeted.TryGetValue(typeof(T), out entryLists))
{
entryLists = new Dictionary <int, List <HandlerEntry> >();
targeted.Add(typeof(T), entryLists);
}
keyHash = key.GetHashCode();
if (!entryLists.TryGetValue(keyHash.Value, out entries))
{
entries = new List <HandlerEntry>();
entryLists.Add(keyHash.Value, entries);
}
if (keyIsWeak)
{
weakKey = new WeakReference(key);
key = null;
}
}
entries.Add(new HandlerEntry(new WeakReference(handler), weakKey, key));
listener = new MessageListener <T>(handler, keyHash);
}
// remove listeners explicitly using this method when they are no longer wanted,
// because waiting for the GC to reclaim your handler is highly undeterministic
public bool RemoveListener <T>(ref MessageListener <T> listener)
{
List <HandlerEntry> entries;
if (!listener.KeyHashCode.HasValue)
{
if (!untargeted.TryGetValue(typeof(T), out entries))
{
return(false);
}
}
else
{
Dictionary <int, List <HandlerEntry> > entryLists;
if (!targeted.TryGetValue(typeof(T), out entryLists))
{
return(false);
}
if (!entryLists.TryGetValue(listener.KeyHashCode.Value, out entries))
{
return(false);
}
}
for (int i = 0; i < entries.Count; ++i)
{
var entry = entries[i];
object handler = entry.Handler.Target;
if (handler == null)
{
entries.RemoveAt(i--);
continue;
}
if (handler.Equals(listener.Handler))
{
entries.RemoveAt(i);
listener = new MessageListener <T>(null, null);
return(true);
}
}
return(false);
}
public void AddListenerWithWeakKey <T>(object key, out MessageListener <T> listener, MessageHandler <T> handler)
{
AddListener(out listener, handler, key, true);
}
public void AddListenerWithStrongKey <T>(object key, out MessageListener <T> listener, MessageHandler <T> handler)
{
AddListener(out listener, handler, key, false);
}
public void AddListener <T>(out MessageListener <T> listener, MessageHandler <T> handler)
{
AddListener(out listener, handler, null, false);
}