//
// Provides boilerplate implementation for implementing asnychronous
// BeginXXXX and EndXXXX methods over a synchronous implementation.
//
public static AsyncResult <T> BeginSync <T>(AsyncCallback asyncCallback, object asyncState, object owner, string operationId, Func <T> syncFunc)
{
Debug.Assert(!string.IsNullOrEmpty(operationId));
Debug.Assert(syncFunc != null);
var asyncResult = new AsyncResult <T>(asyncCallback, asyncState, owner, operationId);
try
{
asyncResult.SetResult(syncFunc());
asyncResult.Complete(null, true);
}
catch (Exception e)
{
asyncResult.Complete(e, true);
}
return(asyncResult);
}
public static AsyncResult Begin(
Func <Func <AsyncCallback>, IEnumerable <IAsyncResult> > starter,
AsyncCallback asyncCallback, object state,
object owner, string operationId)
{
if (starter == null)
{
throw new ArgumentNullException("starter");
}
var result = new AsyncResult(asyncCallback, state, owner, operationId);
IEnumerator <IAsyncResult> are = null;
AsyncCallback quantum = null;
IAsyncResult nar = null;
var busy = false;
var popped = new bool[1];
quantum = ar => // ReSharper disable AccessToModifiedClosure
{
Debug.Assert(are != null);
Debug.Assert(quantum != null);
if (are.Current != null && ar == null)
{
throw new ArgumentNullException("ar");
}
if (busy)
{
// Debug.Assert(ar.CompletedSynchronously);
Debug.Assert(nar == null);
nar = ar;
}
else
{
if (!ReferenceEquals(ar, are.Current))
{
throw new ArgumentException(null, "ar");
}
do
{
bool done;
popped[0] = false;
busy = true;
try
{
done = !are.MoveNext();
}
catch (Exception e)
{
try { are.Dispose(); } // ReSharper disable EmptyGeneralCatchClause
catch { } // ReSharper restore EmptyGeneralCatchClause
result.Complete(e);
return;
}
finally
{
busy = false;
}
if (done)
{
result.Complete();
ar = null;
}
else
{
if (!popped[0])
{
throw new InvalidOperationException();
}
ar = nar;
nar = null;
}
}while (ar != null);
}
};
// ReSharper restore AccessToModifiedClosure
var cbf = new Func <AsyncCallback>(() =>
{
if (popped[0])
{
throw new InvalidOperationException();
}
popped[0] = true;
return(quantum);
});
try
{
are = starter(cbf).GetEnumerator();
}
catch (Exception e)
{
result.Complete(e, true);
return(result);
}
quantum(null);
return(result);
}