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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
/*============================================================
**
**
** Purpose: part of ComEventHelpers APIs which allow binding
** managed delegates to COM's connection point based events.
**
**/
namespace System.Runtime.InteropServices {
using System;
using System.Diagnostics;
// see code:ComEventsHelper#ComEventsArchitecture
internal class ComEventsSink : ICustomQueryInterface
{
#region private fields
private Guid _iidSourceItf;
private ComTypes.IConnectionPoint _connectionPoint;
private int _cookie;
private ComEventsMethod _methods;
private ComEventsSink _next;
#endregion
#region ctor
internal ComEventsSink(object rcw, Guid iid) {
_iidSourceItf = iid;
this.Advise(rcw);
}
#endregion
#region static members
internal static ComEventsSink Find(ComEventsSink sinks, ref Guid iid) {
ComEventsSink sink = sinks;
while (sink != null && sink._iidSourceItf != iid) {
sink = sink._next;
}
return sink;
}
internal static ComEventsSink Add(ComEventsSink sinks, ComEventsSink sink) {
sink._next = sinks;
return sink;
}
internal static ComEventsSink RemoveAll(ComEventsSink sinks) {
while (sinks != null) {
sinks.Unadvise();
sinks = sinks._next;
}
return null;
}
internal static ComEventsSink Remove(ComEventsSink sinks, ComEventsSink sink) {
BCLDebug.Assert(sinks != null, "removing event sink from empty sinks collection");
BCLDebug.Assert(sink != null, "specify event sink is null");
if (sink == sinks) {
sinks = sinks._next;
} else {
ComEventsSink current = sinks;
while (current != null && current._next != sink)
current = current._next;
if (current != null) {
current._next = sink._next;
}
}
sink.Unadvise();
return sinks;
}
#endregion
#region public methods
public ComEventsMethod RemoveMethod(ComEventsMethod method) {
_methods = ComEventsMethod.Remove(_methods, method);
return _methods;
}
public ComEventsMethod FindMethod(int dispid) {
return ComEventsMethod.Find(_methods, dispid);
}
public ComEventsMethod AddMethod(int dispid) {
ComEventsMethod method = new ComEventsMethod(dispid);
_methods = ComEventsMethod.Add(_methods, method);
return method;
}
#endregion
static Guid IID_IManagedObject = new Guid("{C3FCC19E-A970-11D2-8B5A-00A0C9B7C9C4}");
CustomQueryInterfaceResult ICustomQueryInterface.GetInterface(ref Guid iid, out IntPtr ppv) {
ppv = IntPtr.Zero;
if (iid == this._iidSourceItf || iid == typeof(NativeMethods.IDispatch).GUID) {
ppv = Marshal.GetComInterfaceForObject(this, typeof(NativeMethods.IDispatch), CustomQueryInterfaceMode.Ignore);
return CustomQueryInterfaceResult.Handled;
}
else if (iid == IID_IManagedObject)
{
return CustomQueryInterfaceResult.Failed;
}
return CustomQueryInterfaceResult.NotHandled;
}
#region private methods
private void Advise(object rcw) {
BCLDebug.Assert(_connectionPoint == null, "comevent sink is already advised");
ComTypes.IConnectionPointContainer cpc = (ComTypes.IConnectionPointContainer)rcw;
ComTypes.IConnectionPoint cp;
cpc.FindConnectionPoint(ref _iidSourceItf, out cp);
object sinkObject = this;
cp.Advise(sinkObject, out _cookie);
_connectionPoint = cp;
}
private void Unadvise() {
BCLDebug.Assert(_connectionPoint != null, "can not unadvise from empty connection point");
try {
_connectionPoint.Unadvise(_cookie);
Marshal.ReleaseComObject(_connectionPoint);
} catch (System.Exception) {
// swallow all exceptions on unadvise
// the host may not be available at this point
} finally {
_connectionPoint = null;
}
}
#endregion
};
}
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