private void OnCollectionChanged()

in src/Microsoft.Xaml.Behaviors/AttachableCollection.cs [96:164]
65 lines of code
12 McCabe index (conditional complexity)

        private void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
        {
            switch (e.Action)
            {
                // We fix the snapshot to mirror the structure, even if an exception is thrown. This may not be desirable.
                case NotifyCollectionChangedAction.Add:
                    foreach (T item in e.NewItems)
                    {
                        try
                        {
                            this.VerifyAdd(item);
                            this.ItemAdded(item);
                        }
                        finally
                        {
                            this.snapshot.Insert(this.IndexOf(item), item);
                        }
                    }
                    break;

                case NotifyCollectionChangedAction.Replace:
                    foreach (T item in e.OldItems)
                    {
                        this.ItemRemoved(item);
                        this.snapshot.Remove(item);
                    }
                    foreach (T item in e.NewItems)
                    {
                        try
                        {
                            this.VerifyAdd(item);
                            this.ItemAdded(item);
                        }
                        finally
                        {
                            this.snapshot.Insert(this.IndexOf(item), item);
                        }
                    }
                    break;

                case NotifyCollectionChangedAction.Remove:
                    foreach (T item in e.OldItems)
                    {
                        this.ItemRemoved(item);
                        this.snapshot.Remove(item);
                    }
                    break;

                case NotifyCollectionChangedAction.Reset:
                    foreach (T item in this.snapshot)
                    {
                        this.ItemRemoved(item);
                    }
                    this.snapshot = new Collection<T>();
                    foreach (T item in this)
                    {
                        this.VerifyAdd(item);
                        this.ItemAdded(item);
                    }
                    break;
                case NotifyCollectionChangedAction.Move:
                default:
                    Debug.Fail("Unsupported collection operation attempted.");
                    break;
            }
#if DEBUG
			this.VerifySnapshotIntegrity();
#endif
        }