/// <summary>
/// Converts a <see cref="CollectionModification{T}"/> to a list of <see cref="CollectionNotification{T}"/>.
/// </summary>
/// <typeparam name="T">The object that provides modification information.</typeparam>
/// <param name="modification">The <see cref="CollectionModification{T}"/> to be converted.</param>
/// <returns>A list of <see cref="CollectionNotification{T}"/> containing
/// <see cref="CollectionNotificationKind.OnAdded"/> when the specified <paramref name="modification"/> is <see cref="CollectionModificationKind.Add"/>,
/// <see cref="CollectionNotificationKind.OnRemoved"/> when the specified <paramref name="modification"/> is <see cref="CollectionModificationKind.Remove"/>, or
/// <see cref="CollectionNotificationKind.OnCleared"/> when the specified <paramref name="modification"/> is <see cref="CollectionModificationKind.Clear"/>.</returns>
public static IList <CollectionNotification <T> > ToNotifications <T>(this CollectionModification <T> modification)
{
Contract.Requires(modification != null);
Contract.Ensures(Contract.Result <IList <CollectionNotification <T> > >() != null);
Contract.Ensures(Contract.Result <IList <CollectionNotification <T> > >().IsReadOnly);
var list = new List <CollectionNotification <T> >();
IList <T> values;
switch (modification.Kind)
{
case CollectionModificationKind.Add:
values = modification.Values;
for (int i = 0; i < values.Count; i++)
{
list.Add(CollectionNotification.CreateOnAdded <T>(values[i]));
}
break;
case CollectionModificationKind.Remove:
values = modification.Values;
for (int i = 0; i < values.Count; i++)
{
list.Add(CollectionNotification.CreateOnRemoved <T>(values[i]));
}
break;
case CollectionModificationKind.Clear:
list.Add(CollectionNotification.CreateOnCleared <T>());
break;
}
IList <CollectionNotification <T> > result = list.AsReadOnly();
Contract.Assume(result.IsReadOnly);
return(result);
}
/// <summary>
/// Converts <see cref="INotifyCollectionChanged.CollectionChanged"/> events into an observable sequence of <see cref="CollectionNotification{T}"/>.
/// </summary>
/// <typeparam name="T">The object that provides notification information.</typeparam>
/// <param name="source">An implementation of <see cref="INotifyCollectionChanged"/> that raises events when a collection changes.</param>
/// <remarks>
/// An <see cref="NotifyCollectionChangedAction.Add"/> event is projected into zero or more <see cref="CollectionNotificationKind.OnAdded"/> notifications.
/// A <see cref="NotifyCollectionChangedAction.Remove"/> event is projected into zero or more <see cref="CollectionNotificationKind.OnRemoved"/> notifications.
/// A <see cref="NotifyCollectionChangedAction.Move"/> event is projected into zero or more <see cref="CollectionNotificationKind.OnReplaced"/> notifications
/// where <see cref="CollectionNotification{T}.Value"/> and <see cref="CollectionNotification{T}.ReplacedValue"/> refer to the same value.
/// A <see cref="NotifyCollectionChangedAction.Replace"/> event is projected into zero or more <see cref="CollectionNotificationKind.OnReplaced"/> notifications.
/// A <see cref="NotifyCollectionChangedAction.Reset"/> event is projected into a single <see cref="CollectionNotificationKind.OnCleared"/> notification.
/// </remarks>
/// <returns>An observable sequence of <see cref="CollectionNotification{T}"/> objects corresponding to raised events.</returns>
#else
/// <summary>
/// Converts <see cref="INotifyCollectionChanged.CollectionChanged"/> events into an observable sequence of <see cref="CollectionNotification{T}"/>.
/// </summary>
/// <typeparam name="T">The object that provides notification information.</typeparam>
/// <param name="source">An implementation of <see cref="INotifyCollectionChanged"/> that raises events when a collection changes.</param>
/// <remarks>
/// An <see cref="NotifyCollectionChangedAction.Add"/> event is projected into zero or more <see cref="CollectionNotificationKind.OnAdded"/> notifications.
/// A <see cref="NotifyCollectionChangedAction.Remove"/> event is projected into zero or more <see cref="CollectionNotificationKind.OnRemoved"/> notifications.
/// A <see cref="NotifyCollectionChangedAction.Replace"/> event is projected into zero or more <see cref="CollectionNotificationKind.OnReplaced"/> notifications.
/// A <see cref="NotifyCollectionChangedAction.Reset"/> event is projected into a single <see cref="CollectionNotificationKind.OnCleared"/> notification.
/// </remarks>
/// <returns>An observable sequence of <see cref="CollectionNotification{T}"/> objects corresponding to raised events.</returns>
#endif
public static IObservable <CollectionNotification <T> > AsCollectionNotifications <T>(this INotifyCollectionChanged source)
{
Contract.Requires(source != null);
Contract.Ensures(Contract.Result <IObservable <CollectionNotification <T> > >() != null);
return(Observable.FromEventPattern <NotifyCollectionChangedEventHandler, NotifyCollectionChangedEventArgs>(
eh => source.CollectionChanged += eh,
eh => source.CollectionChanged -= eh)
.SelectMany(e =>
{
var args = e.EventArgs;
switch (args.Action)
{
case NotifyCollectionChangedAction.Add:
return EnsureSequence <T>(args.NewItems).Select(CollectionNotification.CreateOnAdded).ToObservable();
case NotifyCollectionChangedAction.Remove:
return EnsureSequence <T>(args.OldItems).Select(CollectionNotification.CreateOnRemoved).ToObservable();
#if !SILVERLIGHT
case NotifyCollectionChangedAction.Move:
return EnsureSequence <T>(args.OldItems).Select(value => CollectionNotification.CreateOnReplaced(value, value)).ToObservable();
#endif
case NotifyCollectionChangedAction.Replace:
return EnsureSequence <T>(args.NewItems)
.Zip(
EnsureSequence <T>(args.OldItems),
(newValue, oldValue) => CollectionNotification.CreateOnReplaced(oldValue, newValue))
.ToObservable();
case NotifyCollectionChangedAction.Reset:
return Observable.Return(CollectionNotification.CreateOnCleared <T>());
default:
throw new InvalidOperationException();
}
}));
}