Steven Kirk
8 years ago
committed by
GitHub
GitHub
26 changed files with 1004 additions and 550 deletions
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// Copyright (c) The Avalonia Project. All rights reserved.
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// Licensed under the MIT license. See licence.md file in the project root for full license information.
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using System; |
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using System.Reactive; |
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using System.Reactive.Disposables; |
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namespace Avalonia.Reactive |
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{ |
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/// <summary>
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/// An <see cref="IObservable{T}"/> with an additional description.
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/// </summary>
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/// <typeparam name="T">The type of the elements in the sequence.</typeparam>
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public class AvaloniaObservable<T> : ObservableBase<T>, IDescription |
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{ |
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private readonly Func<IObserver<T>, IDisposable> _subscribe; |
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/// <summary>
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/// Initializes a new instance of the <see cref="AvaloniaObservable{T}"/> class.
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/// </summary>
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/// <param name="subscribe">The subscribe function.</param>
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/// <param name="description">The description of the observable.</param>
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public AvaloniaObservable(Func<IObserver<T>, IDisposable> subscribe, string description) |
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{ |
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Contract.Requires<ArgumentNullException>(subscribe != null); |
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_subscribe = subscribe; |
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Description = description; |
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} |
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/// <summary>
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/// Gets the description of the observable.
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/// </summary>
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public string Description { get; } |
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/// <inheritdoc/>
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protected override IDisposable SubscribeCore(IObserver<T> observer) |
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{ |
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return _subscribe(observer) ?? Disposable.Empty; |
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} |
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} |
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} |
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using System; |
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namespace Avalonia.Reactive |
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{ |
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internal class AvaloniaPropertyChangedObservable : |
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LightweightObservableBase<AvaloniaPropertyChangedEventArgs>, |
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IDescription |
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{ |
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private readonly WeakReference<IAvaloniaObject> _target; |
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private readonly AvaloniaProperty _property; |
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public AvaloniaPropertyChangedObservable( |
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IAvaloniaObject target, |
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AvaloniaProperty property) |
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{ |
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_target = new WeakReference<IAvaloniaObject>(target); |
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_property = property; |
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} |
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public string Description => $"{_target.GetType().Name}.{_property.Name}"; |
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protected override void Initialize() |
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{ |
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if (_target.TryGetTarget(out var target)) |
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{ |
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target.PropertyChanged += PropertyChanged; |
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} |
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} |
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protected override void Deinitialize() |
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{ |
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if (_target.TryGetTarget(out var target)) |
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{ |
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target.PropertyChanged -= PropertyChanged; |
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} |
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} |
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private void PropertyChanged(object sender, AvaloniaPropertyChangedEventArgs e) |
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{ |
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if (e.Property == _property) |
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{ |
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PublishNext(e); |
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} |
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} |
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} |
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} |
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using System; |
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namespace Avalonia.Reactive |
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{ |
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internal class AvaloniaPropertyObservable<T> : LightweightObservableBase<T>, IDescription |
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{ |
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private readonly WeakReference<IAvaloniaObject> _target; |
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private readonly AvaloniaProperty _property; |
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private T _value; |
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public AvaloniaPropertyObservable( |
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IAvaloniaObject target, |
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AvaloniaProperty property) |
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{ |
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_target = new WeakReference<IAvaloniaObject>(target); |
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_property = property; |
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} |
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public string Description => $"{_target.GetType().Name}.{_property.Name}"; |
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protected override void Initialize() |
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{ |
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if (_target.TryGetTarget(out var target)) |
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{ |
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_value = (T)target.GetValue(_property); |
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target.PropertyChanged += PropertyChanged; |
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} |
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} |
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protected override void Deinitialize() |
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{ |
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if (_target.TryGetTarget(out var target)) |
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{ |
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target.PropertyChanged -= PropertyChanged; |
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} |
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} |
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protected override void Subscribed(IObserver<T> observer, bool first) |
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{ |
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observer.OnNext(_value); |
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} |
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private void PropertyChanged(object sender, AvaloniaPropertyChangedEventArgs e) |
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{ |
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if (e.Property == _property) |
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{ |
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_value = (T)e.NewValue; |
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PublishNext(_value); |
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} |
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} |
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} |
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} |
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using System; |
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using System.Collections.Generic; |
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using System.Reactive; |
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using System.Reactive.Disposables; |
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using System.Threading; |
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using Avalonia.Threading; |
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namespace Avalonia.Reactive |
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{ |
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/// <summary>
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/// Lightweight base class for observable implementations.
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/// </summary>
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/// <typeparam name="T">The observable type.</typeparam>
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/// <remarks>
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/// <see cref="ObservableBase{T}"/> is rather heavyweight in terms of allocations and memory
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/// usage. This class provides a more lightweight base for some internal observable types
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/// in the Avalonia framework.
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/// </remarks>
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public abstract class LightweightObservableBase<T> : IObservable<T> |
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{ |
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private Exception _error; |
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private List<IObserver<T>> _observers = new List<IObserver<T>>(); |
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public IDisposable Subscribe(IObserver<T> observer) |
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{ |
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Contract.Requires<ArgumentNullException>(observer != null); |
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Dispatcher.UIThread.VerifyAccess(); |
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var first = false; |
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for (; ; ) |
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{ |
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if (Volatile.Read(ref _observers) == null) |
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{ |
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if (_error != null) |
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{ |
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observer.OnError(_error); |
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} |
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else |
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{ |
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observer.OnCompleted(); |
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} |
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return Disposable.Empty; |
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} |
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lock (this) |
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{ |
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if (_observers == null) |
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{ |
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continue; |
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} |
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first = _observers.Count == 0; |
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_observers.Add(observer); |
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break; |
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} |
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} |
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if (first) |
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{ |
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Initialize(); |
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} |
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Subscribed(observer, first); |
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return new RemoveObserver(this, observer); |
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} |
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void Remove(IObserver<T> observer) |
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{ |
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if (Volatile.Read(ref _observers) != null) |
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{ |
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lock (this) |
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{ |
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var observers = _observers; |
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if (observers != null) |
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{ |
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observers.Remove(observer); |
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if (observers.Count == 0) |
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{ |
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observers.TrimExcess(); |
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} |
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else |
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{ |
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return; |
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} |
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} else |
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{ |
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return; |
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} |
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} |
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Deinitialize(); |
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} |
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} |
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sealed class RemoveObserver : IDisposable |
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{ |
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LightweightObservableBase<T> _parent; |
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IObserver<T> _observer; |
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public RemoveObserver(LightweightObservableBase<T> parent, IObserver<T> observer) |
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{ |
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_parent = parent; |
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Volatile.Write(ref _observer, observer); |
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} |
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public void Dispose() |
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{ |
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var observer = _observer; |
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Interlocked.Exchange(ref _parent, null)?.Remove(observer); |
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_observer = null; |
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} |
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} |
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protected abstract void Initialize(); |
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protected abstract void Deinitialize(); |
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protected void PublishNext(T value) |
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{ |
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if (Volatile.Read(ref _observers) != null) |
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{ |
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IObserver<T>[] observers; |
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lock (this) |
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{ |
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if (_observers == null) |
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{ |
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return; |
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} |
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observers = _observers.ToArray(); |
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} |
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foreach (var observer in observers) |
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{ |
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observer.OnNext(value); |
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} |
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} |
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} |
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protected void PublishCompleted() |
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{ |
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if (Volatile.Read(ref _observers) != null) |
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{ |
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IObserver<T>[] observers; |
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lock (this) |
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{ |
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if (_observers == null) |
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{ |
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return; |
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} |
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observers = _observers.ToArray(); |
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Volatile.Write(ref _observers, null); |
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} |
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foreach (var observer in observers) |
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{ |
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observer.OnCompleted(); |
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} |
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Deinitialize(); |
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} |
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} |
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protected void PublishError(Exception error) |
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{ |
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if (Volatile.Read(ref _observers) != null) |
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{ |
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IObserver<T>[] observers; |
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lock (this) |
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{ |
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if (_observers == null) |
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{ |
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return; |
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} |
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_error = error; |
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observers = _observers.ToArray(); |
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Volatile.Write(ref _observers, null); |
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} |
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foreach (var observer in observers) |
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{ |
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observer.OnError(error); |
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} |
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Deinitialize(); |
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} |
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} |
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protected virtual void Subscribed(IObserver<T> observer, bool first) |
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{ |
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} |
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} |
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} |
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@ -0,0 +1,76 @@ |
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using System; |
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using Avalonia.Threading; |
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namespace Avalonia.Reactive |
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{ |
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public abstract class SingleSubscriberObservableBase<T> : IObservable<T>, IDisposable |
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{ |
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private Exception _error; |
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private IObserver<T> _observer; |
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private bool _completed; |
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public IDisposable Subscribe(IObserver<T> observer) |
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{ |
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Contract.Requires<ArgumentNullException>(observer != null); |
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Dispatcher.UIThread.VerifyAccess(); |
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if (_observer != null) |
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{ |
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throw new InvalidOperationException("The observable can only be subscribed once."); |
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} |
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if (_error != null) |
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{ |
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observer.OnError(_error); |
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} |
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else if (_completed) |
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{ |
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observer.OnCompleted(); |
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} |
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else |
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{ |
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_observer = observer; |
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Subscribed(); |
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} |
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return this; |
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} |
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void IDisposable.Dispose() |
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{ |
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Unsubscribed(); |
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_observer = null; |
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} |
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protected abstract void Unsubscribed(); |
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protected void PublishNext(T value) |
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{ |
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_observer?.OnNext(value); |
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} |
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protected void PublishCompleted() |
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{ |
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if (_observer != null) |
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{ |
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_observer.OnCompleted(); |
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_completed = true; |
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Unsubscribed(); |
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_observer = null; |
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} |
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} |
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protected void PublishError(Exception error) |
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{ |
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if (_observer != null) |
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{ |
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_observer.OnError(error); |
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_error = error; |
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Unsubscribed(); |
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_observer = null; |
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} |
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} |
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protected abstract void Subscribed(); |
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} |
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} |
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@ -1,85 +0,0 @@ |
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// Copyright (c) The Avalonia Project. All rights reserved.
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// Licensed under the MIT license. See licence.md file in the project root for full license information.
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using System; |
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using System.Reactive; |
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using System.Reactive.Disposables; |
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using System.Reactive.Linq; |
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using System.Reactive.Subjects; |
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using Avalonia.Utilities; |
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namespace Avalonia.Reactive |
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{ |
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internal class WeakPropertyChangedObservable : ObservableBase<object>, |
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IWeakSubscriber<AvaloniaPropertyChangedEventArgs>, IDescription |
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{ |
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private WeakReference<IAvaloniaObject> _sourceReference; |
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private readonly AvaloniaProperty _property; |
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private readonly Subject<object> _changed = new Subject<object>(); |
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private int _count; |
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public WeakPropertyChangedObservable( |
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WeakReference<IAvaloniaObject> source, |
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AvaloniaProperty property, |
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string description) |
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{ |
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_sourceReference = source; |
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_property = property; |
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Description = description; |
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} |
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public string Description { get; } |
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public void OnEvent(object sender, AvaloniaPropertyChangedEventArgs e) |
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{ |
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if (e.Property == _property) |
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{ |
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_changed.OnNext(e.NewValue); |
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} |
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} |
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protected override IDisposable SubscribeCore(IObserver<object> observer) |
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{ |
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IAvaloniaObject instance; |
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if (_sourceReference.TryGetTarget(out instance)) |
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{ |
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if (_count++ == 0) |
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{ |
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WeakSubscriptionManager.Subscribe( |
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instance, |
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nameof(instance.PropertyChanged), |
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this); |
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} |
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observer.OnNext(instance.GetValue(_property)); |
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return Observable.Using(() => Disposable.Create(DecrementCount), _ => _changed) |
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.Subscribe(observer); |
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} |
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else |
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{ |
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_changed.OnCompleted(); |
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observer.OnCompleted(); |
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return Disposable.Empty; |
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} |
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} |
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private void DecrementCount() |
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{ |
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if (--_count == 0) |
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{ |
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IAvaloniaObject instance; |
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if (_sourceReference.TryGetTarget(out instance)) |
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{ |
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WeakSubscriptionManager.Unsubscribe( |
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instance, |
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nameof(instance.PropertyChanged), |
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this); |
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} |
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} |
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} |
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} |
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} |
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