public static ReadOnlyDictionarySubject <TKey, TValue> Collect <TKey, TValue>(this IObservable <CollectionModification <KeyValuePair <TKey, TValue> > > source)
{
Contract.Requires(source != null);
Contract.Ensures(Contract.Result <ReadOnlyDictionarySubject <TKey, TValue> >() != null);
var subscription = new SingleAssignmentDisposable();
var dictionary = new DictionarySubject <TKey, TValue>(subscription);
subscription.Disposable = source.Subscribe(dictionary);
return(new ReadOnlyDictionarySubject <TKey, TValue>(dictionary));
}
/// <summary>
/// Adds the elements from the specified observable sequence into a <see cref="ReadOnlyDictionarySubject{TKey,TValue}"/>.
/// </summary>
/// <typeparam name="TKey">The type of the keys in the dictionary.</typeparam>
/// <typeparam name="TValue">The type of the values in the dictionary.</typeparam>
/// <param name="source">The sequence from which elements are collected.</param>
/// <param name="keySelector">A function that maps values to keys.</param>
/// <returns>A <see cref="ReadOnlyDictionarySubject{TKey,TValue}"/> that receives the elements from the specified sequence.</returns>
public static ReadOnlyDictionarySubject <TKey, TValue> Collect <TKey, TValue>(this IObservable <TValue> source, Func <TValue, TKey> keySelector)
{
Contract.Requires(source != null);
Contract.Requires(keySelector != null);
Contract.Ensures(Contract.Result <ReadOnlyDictionarySubject <TKey, TValue> >() != null);
var subscription = new SingleAssignmentDisposable();
var dictionary = new DictionarySubject <TKey, TValue>(subscription);
subscription.Disposable = source.Subscribe(value => dictionary[keySelector(value)] = value, dictionary.OnError, dictionary.OnCompleted);
return(new ReadOnlyDictionarySubject <TKey, TValue>(dictionary));
}
protected override void Main()
{
var source = new DictionarySubject <string, CustomValue>();
var monitorKeys = new[] { "A", "C", "D", "E", "F", "G" };
// PropertyChanges doesn't work on KeyValuePair because it doesn't have any property change events.
// So we must strip off the key and create a sequence of collection notifications for the values only.
using (source
.Where(
exists: _ => false,
onAdded: added => monitorKeys.Contains(added.Key),
onReplaced: (replaced, added) => monitorKeys.Contains(replaced.Key) && monitorKeys.Contains(added.Key),
onRemoved: removed => monitorKeys.Contains(removed.Key),
onCleared: () => false)
.Select(
_ => null,
added => CollectionNotification.CreateOnAdded(added.Value),
(replaced, added) => CollectionNotification.CreateOnReplaced(replaced.Value, added.Value),
removed => CollectionNotification.CreateOnRemoved(removed.Value),
() => null)
.PropertyChanges()
.Select(e => new { Object = (CustomValue)e.Sender, Property = e.EventArgs.PropertyName })
.Subscribe(value => TraceLine("Changed {0}: {1}", value.Property, value.Object)))
{
var a = new CustomValue("A");
var b = new CustomValue("B");
var c = new CustomValue("C");
source.Add(a.Name, a);
source.Add(b.Name, b);
source.Add(c.Name, c);
a.Child = new CustomValue("D");
b.Child = new CustomValue("E");
c.Child = new CustomValue("F");
a.Child.Child = new CustomValue("G");
a.Number = 1;
b.Number = 1;
c.Number = 1;
a.Child.Number = 100;
b.Child.Number = 101;
c.Child.Number = 102;
var child = a.Child;
var grandchild = child.Child;
grandchild.Number = 103;
child.Child = null;
grandchild.Number = 104;
child.Number = 105;
a.Child = null;
child.Number = 106;
source.Remove(a.Name);
a.Number = 2;
b.Number = 2;
c.Number = 2;
child.Number = 200;
b.Child.Number = 201;
c.Child.Number = 202;
grandchild.Number = 203;
source.Remove(b.Name);
source.Remove(c.Name);
a.Number = 4;
b.Number = 4;
c.Number = 4;
child.Number = 300;
b.Child.Number = 301;
c.Child.Number = 302;
grandchild.Number = 303;
}
}
