private static Task <T> FromAsync <T>(Func <AsyncCallback, IAsyncResult> begin, Func <IAsyncResult, T> end)
{
var tcs = new DispatchingTaskCompletionSource <T>();
try
{
var result = begin(ar =>
{
if (!ar.CompletedSynchronously)
{
CompleteAsync(tcs, ar, end);
}
});
if (result.CompletedSynchronously)
{
CompleteAsync(tcs, result, end);
}
}
catch (Exception ex)
{
tcs.TrySetException(ex);
}
return(tcs.Task);
}
private static void CompleteAsync <T>(DispatchingTaskCompletionSource <T> tcs, IAsyncResult ar, Func <IAsyncResult, T> end)
{
try
{
tcs.TrySetResult(end(ar));
}
catch (OperationCanceledException)
{
tcs.TrySetCanceled();
}
catch (Exception ex)
{
tcs.TrySetException(ex);
}
}