public void AddNestedMerge(int n)
{
var source = new ObservableCollection <Fake>();
var path = NotifyingPath.GetOrCreate <Fake, int>(x => x.Next.Next.Value);
using (var view = source.AsMappingView(x => x.ObservePropertyChanged(path, signalInitial: true)))
{
var sw = Stopwatch.StartNew();
using (var subject = new Subject <IObservable <EventPattern <PropertyChangedEventArgs> > >())
{
using (subject.Switch()
.Publish()
.RefCount()
.Subscribe(_ => { }))
{
for (var i = 0; i < n; i++)
{
var fake = new Fake();
source.Add(fake);
subject.OnNext(view.Merge());
}
}
}
sw.Stop();
Console.WriteLine("// source.ObserveItemPropertyChanged(x => x.Next.Next.Value): {0} Adds took {1} ms {2:F3} ms each. {3}", n, sw.ElapsedMilliseconds, sw.Elapsed.TotalMilliseconds / n, DateTime.Now.ToShortDateString());
}
}
private static IDisposable ItemPropertyChangedCore <TCollection, TItem, TProperty, T>(
this IObservable <TCollection> source,
IObserver <T> observer,
Expression <Func <TItem, TProperty> > property,
Func <TItem, object, PropertyChangedEventArgs, SourceAndValue <INotifyPropertyChanged, TProperty>, T> create)
where TCollection : class, IEnumerable <TItem>, INotifyCollectionChanged
where TItem : class, INotifyPropertyChanged
{
var tracker = ItemsTracker.Create((TCollection)null, NotifyingPath.GetOrCreate(property));
tracker.TrackedItemChanged += Handler;
var subscription = source.Subscribe(x => tracker.UpdateSource(x));
return(new CompositeDisposable(3)
{
Disposable.Create(() => tracker.TrackedItemChanged -= Handler),
tracker,
subscription,
});
void Handler(TItem item, object sender, PropertyChangedEventArgs args, SourceAndValue <INotifyPropertyChanged, TProperty> sourceAndValue)
{
observer.OnNext(create(item, sender, args, sourceAndValue));
}
}
/// <summary>
/// Create an <see cref="ObservableAndCriteria"/> to be passed in as constructor argument.
/// </summary>
/// <param name="source">The source instance.</param>
/// <param name="path">The property path to listen to changes for on source.</param>
/// <param name="value">The value when satisfied.</param>
/// <param name="compare">How to compare actual value and <paramref name="value"/>.</param>
protected static ObservableAndCriteria For <TSource, TValue>(
TSource source,
Expression <Func <TSource, TValue> > path,
TValue value,
Func <Maybe <TValue>, TValue, bool?> compare)
where TSource : class, INotifyPropertyChanged
{
Ensure.NotNull(source, nameof(source));
Ensure.NotNull(path, nameof(path));
var notifyingPath = NotifyingPath.GetOrCreate(path);
return(new ObservableAndCriteria(
Observable.Create <object>(o =>
{
var tracker = notifyingPath.CreateTracker(source);
void Handler(IPropertyTracker _, object __, PropertyChangedEventArgs args, SourceAndValue <INotifyPropertyChanged, TValue> ___) => o.OnNext(args);
tracker.TrackedPropertyChanged += Handler;
return Disposable.Create(() =>
{
tracker.TrackedPropertyChanged -= Handler;
tracker.Dispose();
});
}),
() => compare(notifyingPath.SourceAndValue(source).Value, value)));
}
private static IDisposable ObserveItemPropertyChangedCore <TCollection, TItem, TProperty, T>(
this TCollection source,
IObserver <T> o,
Expression <Func <TItem, TProperty> > property,
bool signalInitial,
Func <TItem, object, PropertyChangedEventArgs, SourceAndValue <INotifyPropertyChanged, TProperty>, T> create)
where TCollection : class, IEnumerable <TItem>, INotifyCollectionChanged
where TItem : class, INotifyPropertyChanged
{
var tracker = ItemsTracker.Create(
signalInitial
? null
: source,
NotifyingPath.GetOrCreate(property));
TrackedItemPropertyChangedEventHandler <TItem, TProperty> handler =
(item, sender, args, sourceAndValue) => o.OnNext(
create(
item,
sender,
args,
sourceAndValue));
tracker.TrackedItemChanged += handler;
if (signalInitial)
{
tracker.UpdateSource(source);
}
return(new CompositeDisposable(2)
{
Disposable.Create(() => tracker.TrackedItemChanged -= handler),
tracker
});
}
private static IObservable <T> ObservePropertyChangedCore <TNotifier, TProperty, T>(
this TNotifier source,
NotifyingPath <TNotifier, TProperty> notifyingPath,
Func <object, PropertyChangedEventArgs, T> create,
bool signalInitial = true)
where TNotifier : class, INotifyPropertyChanged
{
if (signalInitial)
{
return(Observable.Return(
create(
notifyingPath.SourceAndValue(source).Source,
CachedEventArgs.GetOrCreatePropertyChangedEventArgs(string.Empty)))
.Concat(source.ObservePropertyChangedCore(notifyingPath, create, signalInitial: false)));
}
if (notifyingPath.Count > 1)
{
return(Observable.Create <T>(
o =>
{
var tracker = notifyingPath.CreateTracker(source);
void Handler(IPropertyTracker _, object sender, PropertyChangedEventArgs e, SourceAndValue <INotifyPropertyChanged, TProperty> __) => o.OnNext(create(sender, e));
tracker.TrackedPropertyChanged += Handler;
return new CompositeDisposable(2)
{
tracker,
Disposable.Create(() => tracker.TrackedPropertyChanged -= Handler),
};
}));
}
return(ObservePropertyChangedCore(source, notifyingPath.Last.Property.Name, create, signalInitial: false));
}
/// <summary>
/// Observe property changes for the path <paramref name="source"/>.
/// This signals when any of the items in tha path signals.
/// </summary>
/// <typeparam name="TNotifier">The source type.</typeparam>
/// <typeparam name="TProperty">The property type.</typeparam>
/// <param name="source">The source instance.</param>
/// <param name="property">An expression specifying the property path.</param>
/// <param name="signalInitial"> If true OnNext is called immediately on subscribe. </param>
/// <returns>The <see cref="IObservable{T}"/>.</returns>
public static IObservable <PropertyChangedEventArgs> ObserveFullPropertyPathSlim <TNotifier, TProperty>(this TNotifier source, Expression <Func <TNotifier, TProperty> > property, bool signalInitial = true)
where TNotifier : class, INotifyPropertyChanged
{
if (source is null)
{
throw new ArgumentNullException(nameof(source));
}
if (property is null)
{
throw new ArgumentNullException(nameof(property));
}
var notifyingPath = NotifyingPath.GetOrCreate(property);
if (notifyingPath.Count < 2)
{
var message = "Expected path to have more than one item.\r\n" +
$"The path was {property}\r\n" +
"Did you mean to call ObservePropertyChangedSlim?";
throw new ArgumentException(message, nameof(property));
}
return(ObserveFullPropertyPathCore(source, notifyingPath, (_, e) => e, signalInitial));
}
private static IObservable <T> ObserveValueCore <TNotifier, TProperty, T>(
this TNotifier source,
NotifyingPath <TNotifier, TProperty> notifyingPath,
Func <object?, PropertyChangedEventArgs, Maybe <TProperty>, T> create,
bool signalInitial = true)
where TNotifier : class, INotifyPropertyChanged
{
if (signalInitial)
{
return(Observable.Defer(
() =>
{
var sourceAndValue = notifyingPath.SourceAndValue(source);
return Observable.Return(
create(
sourceAndValue.Source,
CachedEventArgs.GetOrCreatePropertyChangedEventArgs(string.Empty),
sourceAndValue.Value));
})
.Concat(source.ObserveValueCore(notifyingPath, create, signalInitial: false)));
}
if (notifyingPath.Count > 1)
{
return(Observable.Create <T>(
o =>
{
var tracker = notifyingPath.CreateTracker(source);
tracker.TrackedPropertyChanged += Handler;
return new CompositeDisposable(2)
{
tracker,
Disposable.Create(() => tracker.TrackedPropertyChanged -= Handler),
};
void Handler(IPropertyTracker _, object sender, PropertyChangedEventArgs args, SourceAndValue <INotifyPropertyChanged?, TProperty> sourceAndValue)
{
o.OnNext(create(sender, args, sourceAndValue.Value));
}
}));
}
return(Observable.Create <T>(
o =>
{
void Handler(object sender, PropertyChangedEventArgs e)
{
if (e.IsMatch(notifyingPath.Last.Property))
{
var value = notifyingPath.Last.GetMaybe(sender);
o.OnNext(create(sender, e, value));
}
}
source.PropertyChanged += Handler;
return Disposable.Create(() => source.PropertyChanged -= Handler);
}));
}
public void ToStringTest()
{
var path = NotifyingPath.GetOrCreate <Fake, int>(x => x.Level1.Value);
Assert.AreEqual("x => x.Level1.Value", path.ToString());
path = NotifyingPath.GetOrCreate <Fake, int>(x => x.Level1.Level2.Value);
Assert.AreEqual("x => x.Level1.Level2.Value", path.ToString());
}
/// <summary>
/// Extension method for listening to property changes.
/// Handles nested x => x.Level1.Level2.Level3
/// Unsubscribes & subscribes when each level changes.
/// Handles nulls.
/// </summary>
/// <param name="source">The source instance to track changes for. </param>
/// <param name="propertyPath">
/// A cached property path. Creating the property path from Expression<Func<TNotifier, TProperty>> is a bit expensive so caching can make sense.
/// </param>
/// <param name="signalInitial">
/// If true OnNext is called immediately on subscribe.
/// </param>
internal static IObservable <EventPattern <PropertyChangedEventArgs> > ObservePropertyChanged <TNotifier, TProperty>(
this TNotifier source,
NotifyingPath <TNotifier, TProperty> propertyPath,
bool signalInitial = true)
where TNotifier : class, INotifyPropertyChanged
{
return(ObservePropertyChangedCore(
source,
propertyPath,
(sender, args) => new EventPattern <PropertyChangedEventArgs>(sender, args),
signalInitial));
}
public void ToStringTest()
{
#pragma warning disable CS8602 // Dereference of a possibly null reference.
var path = NotifyingPath.GetOrCreate <Fake, int>(x => x.Level1.Value);
#pragma warning restore CS8602 // Dereference of a possibly null reference.
Assert.AreEqual("x => x.Level1.Value", path.ToString());
#pragma warning disable CS8602 // Dereference of a possibly null reference.
path = NotifyingPath.GetOrCreate <Fake, int>(x => x.Level1.Level2.Value);
#pragma warning restore CS8602 // Dereference of a possibly null reference.
Assert.AreEqual("x => x.Level1.Level2.Value", path.ToString());
}
internal static IObservable <EventPattern <PropertyChangedAndValueEventArgs <TProperty> > > ObservePropertyChangedWithValue <TNotifier, TProperty>(
this TNotifier source,
NotifyingPath <TNotifier, TProperty> propertyPath,
bool signalInitial = true)
where TNotifier : class, INotifyPropertyChanged
{
return(source.ObserveValueCore(
propertyPath,
(sender, e, value) => new EventPattern <PropertyChangedAndValueEventArgs <TProperty> >(
sender,
new PropertyChangedAndValueEventArgs <TProperty>(e.PropertyName, value)),
signalInitial));
}
/// <summary>
/// Observe propertychanges with values.
/// </summary>
/// <param name="source">The source.</param>
/// <param name="property">An expression specifying the property path.</param>
/// <param name="signalInitial">If true OnNext is called immediately on subscribe.</param>
/// <typeparam name="TNotifier">The type of <paramref name="source"/>.</typeparam>
/// <typeparam name="TProperty">The type of the last property in the path.</typeparam>
/// <returns>The <see cref="IObservable{T}"/> of type of type <see cref="EventPattern{TArgs}"/> of type <see cref="PropertyChangedAndValueEventArgs{TProperty}"/>.</returns>
public static IObservable <EventPattern <PropertyChangedAndValueEventArgs <TProperty> > > ObservePropertyChangedWithValue <TNotifier, TProperty>(
this TNotifier source,
Expression <Func <TNotifier, TProperty> > property,
bool signalInitial = true)
where TNotifier : class, INotifyPropertyChanged
{
Ensure.NotNull(source, nameof(source));
Ensure.NotNull(property, nameof(property));
var notifyingPath = NotifyingPath.GetOrCreate(property);
return(source.ObservePropertyChangedWithValue(notifyingPath, signalInitial));
}
/// <summary>
/// Extension method for listening to property changes.
/// Handles nested x => x.Level1.Level2.Level3
/// Unsubscribes & subscribes when each level changes.
/// Handles nulls.
/// </summary>
/// <param name="source">The source instance to track changes for. </param>
/// <param name="property">
/// An expression specifying the property path to track.
/// Example x => x.Foo.Bar.Meh.
/// </param>
/// <param name="signalInitial">
/// If true OnNext is called immediately on subscribe.
/// </param>
public static IObservable <PropertyChangedEventArgs> ObservePropertyChangedSlim <TNotifier, TProperty>(
this TNotifier source,
Expression <Func <TNotifier, TProperty> > property,
bool signalInitial = true)
where TNotifier : class, INotifyPropertyChanged
{
Ensure.NotNull(source, nameof(source));
Ensure.NotNull(property, nameof(property));
var notifyingPath = NotifyingPath.GetOrCreate(property);
return(ObservePropertyChangedCore(source, notifyingPath, (_, e) => e, signalInitial));
}
public NestedChanges(TCollection source, Expression <Func <TItem, TValue> > selector)
{
var path = NotifyingPath.GetOrCreate(selector);
this.source = new MappingView <TItem, ValueTracker>(
source: source,
factory: Mapper.Create <TItem, ValueTracker>(x => new ValueTracker(this, x, path), x => x.Dispose()),
bufferTime: TimeSpan.Zero,
scheduler: null,
leaveOpen: true);
this.subscription = source.ObserveCollectionChangedSlim(signalInitial: false)
.Subscribe(this.OnSourceChanged);
}
/// <summary>
/// Extension method for listening to property changes.
/// Handles nested x => x.Level1.Level2.Level3
/// Unsubscribes & subscribes when each level changes.
/// Handles nulls.
/// </summary>
/// <param name="source">The source instance to track changes for. </param>
/// <param name="property">
/// An expression specifying the property path to track.
/// Example x => x.Foo.Bar.Meh.
/// </param>
/// <param name="signalInitial">
/// If true OnNext is called immediately on subscribe.
/// </param>
public static IObservable <Maybe <TProperty> > ObserveValue <TNotifier, TProperty>(
this TNotifier source,
Expression <Func <TNotifier, TProperty> > property,
bool signalInitial = true)
where TNotifier : class, INotifyPropertyChanged
{
Ensure.NotNull(source, nameof(source));
Ensure.NotNull(property, nameof(property));
var notifyingPath = NotifyingPath.GetOrCreate(property);
return(source.ObserveValueCore(
notifyingPath,
(_, __, value) => value,
signalInitial)
.DistinctUntilChanged());
}
public void AddNested(int n)
{
var source = new ObservableCollection <Fake>();
var path = NotifyingPath.GetOrCreate <Fake, int>(x => x.Next.Next.Value);
using var view = source.AsMappingView(x => x.ObservePropertyChanged(path, signalInitial: true));
var sw = Stopwatch.StartNew();
for (var i = 0; i < n; i++)
{
var fake = new Fake();
source.Add(fake);
}
sw.Stop();
Console.WriteLine("// source.ObserveItemPropertyChanged(x => x.Next.Next.Value): {0} Adds took {1} ms {2:F3} ms each. {3}", n, sw.ElapsedMilliseconds, sw.Elapsed.TotalMilliseconds / n, DateTime.Now.ToShortDateString());
}
/// <summary>
/// Extension method for listening to property changes.
/// Handles nested x => x.Level1.Level2.Level3
/// Unsubscribes & subscribes when each level changes.
/// Handles nulls.
/// </summary>
/// <typeparam name="TNotifier">The source type.</typeparam>
/// <typeparam name="TProperty">The property type.</typeparam>
/// <param name="source">The source instance to track changes for. </param>
/// <param name="property">
/// An expression specifying the property path to track.
/// Example x => x.Foo.Bar.Meh.
/// </param>
/// <param name="signalInitial">
/// If true OnNext is called immediately on subscribe.
/// </param>
/// <returns>An <see cref="IObservable{T}"/>.</returns>
public static IObservable <PropertyChangedEventArgs> ObservePropertyChangedSlim <TNotifier, TProperty>(
this TNotifier source,
Expression <Func <TNotifier, TProperty> > property,
bool signalInitial = true)
where TNotifier : class, INotifyPropertyChanged
{
if (source is null)
{
throw new ArgumentNullException(nameof(source));
}
if (property is null)
{
throw new ArgumentNullException(nameof(property));
}
var notifyingPath = NotifyingPath.GetOrCreate(property);
return(ObservePropertyChangedCore(source, notifyingPath, (_, e) => e, signalInitial));
}
public static IObservable <EventPattern <PropertyChangedAndValueEventArgs <TProperty> > > ObservePropertyChangedWithValue <TNotifier, TProperty>(
this TNotifier source,
Expression <Func <TNotifier, TProperty> > property,
bool signalInitial = true)
where TNotifier : class, INotifyPropertyChanged
{
if (source is null)
{
throw new ArgumentNullException(nameof(source));
}
if (property is null)
{
throw new ArgumentNullException(nameof(property));
}
var notifyingPath = NotifyingPath.GetOrCreate(property);
return(source.ObservePropertyChangedWithValue(notifyingPath, signalInitial));
}
/// <summary>
/// Extension method for listening to property changes.
/// Handles nested x => x.Level1.Level2.Level3
/// Unsubscribes & subscribes when each level changes.
/// Handles nulls.
/// </summary>
/// <typeparam name="TNotifier">The source type.</typeparam>
/// <typeparam name="TProperty">The property type.</typeparam>
/// <param name="source">The source instance to track changes for. </param>
/// <param name="property">
/// An expression specifying the property path to track.
/// Example x => x.Foo.Bar.Meh.
/// </param>
/// <param name="signalInitial">
/// If true OnNext is called immediately on subscribe.
/// </param>
/// <returns>The <see cref="IObservable{T}"/>.</returns>
public static IObservable <Maybe <TProperty> > ObserveValue <TNotifier, TProperty>(
this TNotifier source,
Expression <Func <TNotifier, TProperty> > property,
bool signalInitial = true)
where TNotifier : class, INotifyPropertyChanged
{
if (source is null)
{
throw new ArgumentNullException(nameof(source));
}
if (property is null)
{
throw new ArgumentNullException(nameof(property));
}
var notifyingPath = NotifyingPath.GetOrCreate(property);
return(source.ObserveValueCore(
notifyingPath,
(_, _, value) => value,
signalInitial)
.DistinctUntilChanged());
}
private static IObservable <T> ObserveFullPropertyPathCore <TNotifier, TProperty, T>(this TNotifier source, NotifyingPath <TNotifier, TProperty> notifyingPath, Func <object, PropertyChangedEventArgs, T> create, bool signalInitial = true)
where TNotifier : class, INotifyPropertyChanged
{
if (signalInitial)
{
return(Observable.Return(
create(
notifyingPath.SourceAndValue(source)
.Source,
CachedEventArgs.GetOrCreatePropertyChangedEventArgs(string.Empty)))
.Concat(source.ObserveFullPropertyPathCore(notifyingPath, create, signalInitial: false)));
}
return(Observable.Create <T>(
o =>
{
#pragma warning disable IDISP001 // Dispose created.
var tracker = notifyingPath.CreateTracker(source);
#pragma warning restore IDISP001 // Dispose created.
void Handler(object sender, PropertyChangedEventArgs e) => o.OnNext(create(sender, e));
foreach (var propertyTracker in tracker)
{
propertyTracker.TrackedPropertyChanged += Handler;
}
return Disposable.Create(
() =>
{
foreach (var propertyTracker in tracker)
{
propertyTracker.TrackedPropertyChanged -= Handler;
}
tracker.Dispose();
});
}));
}
public object NotifyingPathGetOrCreateTwoItemPath()
{
return(NotifyingPath.GetOrCreate(TwoItemPath));
}
public object NotifyingPathGetOrCreateSingleItemPath()
{
return(NotifyingPath.GetOrCreate(SingleItemPath));
}
