File size: 3,310 Bytes
8c763fb | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 | // Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System;
using System.Dynamic;
using System.Linq.Expressions;
using System.Management.Automation.InteropServices;
namespace System.Management.Automation.ComInterop
{
internal sealed class BoundDispEvent : DynamicObject
{
private readonly object _rcw;
private readonly Guid _sourceIid;
private readonly int _dispid;
internal BoundDispEvent(object rcw, Guid sourceIid, int dispid)
{
_rcw = rcw;
_sourceIid = sourceIid;
_dispid = dispid;
}
/// <summary>
/// Provides the implementation of performing AddAssign and SubtractAssign binary operations.
/// </summary>
/// <param name="binder">The binder provided by the call site.</param>
/// <param name="handler">The handler for the operation.</param>
/// <param name="result">The result of the operation.</param>
/// <returns>True if the operation is complete, false if the call site should determine behavior.</returns>
public override bool TryBinaryOperation(BinaryOperationBinder binder, object handler, out object result)
{
if (binder.Operation == ExpressionType.AddAssign)
{
result = InPlaceAdd(handler);
return true;
}
if (binder.Operation == ExpressionType.SubtractAssign)
{
result = InPlaceSubtract(handler);
return true;
}
result = null;
return false;
}
private static void VerifyHandler(object handler)
{
if (handler is Delegate && handler.GetType() != typeof(Delegate))
{
return; // delegate
}
if (handler is IDynamicMetaObjectProvider)
{
return; // IDMOP
}
if (handler is DispCallable)
{
return;
}
throw Error.UnsupportedHandlerType();
}
/// <summary>
/// Adds a handler to an event.
/// </summary>
/// <param name="handler">The handler to be added.</param>
/// <returns>The original event with handler added.</returns>
private object InPlaceAdd(object handler)
{
Requires.NotNull(handler);
VerifyHandler(handler);
ComEventsSink comEventSink = ComEventsSink.FromRuntimeCallableWrapper(_rcw, _sourceIid, true);
comEventSink.AddHandler(_dispid, handler);
return this;
}
/// <summary>
/// Removes handler from the event.
/// </summary>
/// <param name="handler">The handler to be removed.</param>
/// <returns>The original event with handler removed.</returns>
private object InPlaceSubtract(object handler)
{
Requires.NotNull(handler);
VerifyHandler(handler);
ComEventsSink comEventSink = ComEventsSink.FromRuntimeCallableWrapper(_rcw, _sourceIid, false);
comEventSink?.RemoveHandler(_dispid, handler);
return this;
}
}
}
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