65 lines
2.6 KiB
C#
65 lines
2.6 KiB
C#
// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT License.
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// See the LICENSE file in the project root for more information.
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using System.Threading;
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namespace System.Reactive.Disposables
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{
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/// <summary>
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/// Represents a disposable resource which only allows a single assignment of its underlying disposable resource.
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/// If an underlying disposable resource has already been set, future attempts to set the underlying disposable resource will throw an <see cref="InvalidOperationException"/>.
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/// </summary>
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public struct SingleAssignmentDisposableValue
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{
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private IDisposable? _current;
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/// <summary>
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/// Gets a value that indicates whether the object is disposed.
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/// </summary>
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public bool IsDisposed =>
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// We use a sentinel value to indicate we've been disposed. This sentinel never leaks
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// to the outside world (see the Disposable property getter), so no-one can ever assign
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// this value to us manually.
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Volatile.Read(ref _current) == BooleanDisposable.True;
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/// <summary>
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/// Gets or sets the underlying disposable. After disposal, the result of getting this property is undefined.
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/// </summary>
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/// <exception cref="InvalidOperationException">Thrown if the <see cref="SingleAssignmentDisposable"/> has already been assigned to.</exception>
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public IDisposable? Disposable
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{
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get => Disposables.Disposable.GetValueOrDefault(ref _current);
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set
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{
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var result = Disposables.Disposable.TrySetSingle(ref _current, value);
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if (result == TrySetSingleResult.AlreadyAssigned)
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{
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throw new InvalidOperationException(Strings_Core.DISPOSABLE_ALREADY_ASSIGNED);
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}
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}
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}
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/// <summary>
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/// Disposes the underlying disposable.
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/// </summary>
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public void Dispose()
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{
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Disposables.Disposable.Dispose(ref _current);
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}
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/// <inheritdoc/>
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public override bool Equals(object? obj) => false;
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/// <inheritdoc/>
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public override int GetHashCode() => 0;
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#pragma warning disable IDE0060 // (Remove unused parameter.) Required part of public API
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public static bool operator ==(SingleAssignmentDisposableValue left, SingleAssignmentDisposableValue right) => false;
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public static bool operator !=(SingleAssignmentDisposableValue left, SingleAssignmentDisposableValue right) => true;
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#pragma warning restore IDE0060
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}
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}
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