private static Task <TOuterResult> ThenImpl <TTask, TOuterResult>(this TTask task, Func <TTask, Task <TOuterResult> > continuation, CancellationToken cancellationToken, bool runSynchronously)
where TTask : Task
{
// Stay on the same thread if we can
if (task.IsCompleted)
{
if (task.IsFaulted)
{
return(TaskHelpers.FromErrors <TOuterResult>(task.Exception.InnerExceptions));
}
if (task.IsCanceled || cancellationToken.IsCancellationRequested)
{
return(TaskHelpers.Canceled <TOuterResult>());
}
if (task.Status == TaskStatus.RanToCompletion)
{
try
{
return(continuation(task));
}
catch (Exception ex)
{
return(TaskHelpers.FromError <TOuterResult>(ex));
}
}
}
// Split into a continuation method so that we don't create a closure unnecessarily
return(ThenImplContinuation(task, continuation, cancellationToken, runSynchronously));
}
/// <summary>
/// Changes the return value of a task to the given result, if the task ends in the RanToCompletion state.
/// This potentially imposes an extra ContinueWith to convert a non-completed task, so use this with caution.
/// </summary>
internal static Task <TResult> ToTask <TResult>(this Task task, CancellationToken cancellationToken = default(CancellationToken), TResult result = default(TResult))
{
if (task == null)
{
return(null);
}
// Stay on the same thread if we can
if (task.IsCompleted)
{
if (task.IsFaulted)
{
return(TaskHelpers.FromErrors <TResult>(task.Exception.InnerExceptions));
}
if (task.IsCanceled || cancellationToken.IsCancellationRequested)
{
return(TaskHelpers.Canceled <TResult>());
}
if (task.Status == TaskStatus.RanToCompletion)
{
return(TaskHelpers.FromResult(result));
}
}
// Split into a continuation method so that we don't create a closure unnecessarily
return(ToTaskContinuation(task, result));
}
public static Task <TResult> ToTask <TResult>(this Task task,
CancellationToken cancellationToken = default(CancellationToken), TResult result = default(TResult))
{
if (task == null)
{
return(null);
}
if (task.IsCompleted)
{
if (task.IsFaulted)
{
return(TaskHelpers.FromErrors <TResult>(task.Exception.InnerExceptions));
}
if (task.IsCanceled || cancellationToken.IsCancellationRequested)
{
return(TaskHelpers.Canceled <TResult>());
}
if (task.Status == TaskStatus.RanToCompletion)
{
return(TaskHelpers.FromResult(result));
}
}
return(ToTaskContinuation(task, result));
}
private static Task <TOuterResult> ThenImpl <TTask, TOuterResult>(this TTask task,
Func <TTask, Task <TOuterResult> > continuation, CancellationToken cancellationToken, bool runSynchronously)
where TTask : Task
{
if (task.IsCompleted)
{
if (task.IsFaulted)
{
return(TaskHelpers.FromErrors <TOuterResult>(task.Exception.InnerExceptions));
}
if (task.IsCanceled || cancellationToken.IsCancellationRequested)
{
return(TaskHelpers.Canceled <TOuterResult>());
}
if (task.Status == TaskStatus.RanToCompletion)
{
try
{
return(continuation(task));
}
catch (Exception ex)
{
return(TaskHelpers.FromError <TOuterResult>(ex));
}
}
}
return(ThenImplContinuation(task, continuation, cancellationToken, runSynchronously));
}
public void FromErrors_Generic_ReturnsFaultedTaskWithGivenExceptions()
{
var exceptions = new[] { new Exception(), new InvalidOperationException() };
Task <string> result = TaskHelpers.FromErrors <string>(exceptions);
Assert.NotNull(result);
Assert.True(result.IsFaulted);
Assert.Equal(exceptions, result.Exception.InnerExceptions.ToArray());
}
internal static Task <TOuterResult> CastFromobject <TOuterResult>(this Task <object> task)
{
// Stay on the same thread if we can
if (task.IsCompleted)
{
if (task.IsFaulted)
{
return(TaskHelpers.FromErrors <TOuterResult>(task.Exception.InnerExceptions));
}
if (task.IsCanceled)
{
return(TaskHelpers.Canceled <TOuterResult>());
}
if (task.Status == TaskStatus.RanToCompletion)
{
try
{
return(TaskHelpers.FromResult <TOuterResult>((TOuterResult)task.Result));
}
catch (Exception exception)
{
return(TaskHelpers.FromError <TOuterResult>(exception));
}
}
}
TaskCompletionSource <TOuterResult> tcs = new TaskCompletionSource <TOuterResult>();
// schedule a synchronous task to cast: no need to worry about sync context or try/catch
task.ContinueWith(innerTask =>
{
if (innerTask.IsFaulted)
{
tcs.SetException(innerTask.Exception.InnerExceptions);
}
else if (innerTask.IsCanceled)
{
tcs.SetCanceled();
}
else
{
try
{
tcs.SetResult((TOuterResult)innerTask.Result);
}
catch (Exception exception)
{
tcs.SetException(exception);
}
}
}, TaskContinuationOptions.ExecuteSynchronously);
return(tcs.Task);
}
public static Task <TOuterResult> CastFromObject <TOuterResult>(this Task <object> task)
{
if (task.IsCompleted)
{
if (task.IsFaulted)
{
return(TaskHelpers.FromErrors <TOuterResult>(task.Exception.InnerExceptions));
}
if (task.IsCanceled)
{
return(TaskHelpers.Canceled <TOuterResult>());
}
if (task.Status == TaskStatus.RanToCompletion)
{
try
{
return(TaskHelpers.FromResult((TOuterResult)task.Result));
}
catch (Exception exception)
{
return(TaskHelpers.FromError <TOuterResult>(exception));
}
}
}
var tcs = new TaskCompletionSource <TOuterResult>();
task.ContinueWith(innerTask =>
{
if (innerTask.IsFaulted)
{
tcs.SetException(innerTask.Exception.InnerExceptions);
}
else if (innerTask.IsCanceled)
{
tcs.SetCanceled();
}
else
{
try
{
tcs.SetResult((TOuterResult)innerTask.Result);
}
catch (Exception exception)
{
tcs.SetException(exception);
}
}
}, TaskContinuationOptions.ExecuteSynchronously);
return(tcs.Task);
}
private static Task <TOuterResult> ThenImplContinuation <TOuterResult, TTask>(TTask task, Func <TTask, Task <TOuterResult> > continuation, CancellationToken cancellationToken)
where TTask : Task
{
SynchronizationContext syncContext = SynchronizationContext.Current;
return(task.ContinueWith(innerTask =>
{
if (innerTask.IsFaulted)
{
return TaskHelpers.FromErrors <TOuterResult>(innerTask.Exception.InnerExceptions);
}
if (innerTask.IsCanceled || cancellationToken.IsCancellationRequested)
{
return TaskHelpers.Canceled <TOuterResult>();
}
TaskCompletionSource <Task <TOuterResult> > tcs = new TaskCompletionSource <Task <TOuterResult> >();
if (syncContext != null)
{
syncContext.Post(state =>
{
try
{
tcs.TrySetResult(continuation(task));
}
catch (Exception ex)
{
tcs.TrySetException(ex);
}
}, state: null);
}
else
{
tcs.TrySetResult(continuation(task));
}
return tcs.Task.FastUnwrap();
}).FastUnwrap());
}
public static Task <object> CastToObject(this Task task)
{
if (task.IsCompleted)
{
if (task.IsFaulted)
{
return(TaskHelpers.FromErrors <object>(task.Exception.InnerExceptions));
}
if (task.IsCanceled)
{
return(TaskHelpers.Canceled <object>());
}
if (task.Status == TaskStatus.RanToCompletion)
{
return(TaskHelpers.FromResult((object)null));
}
}
var tcs = new TaskCompletionSource <object>();
task.ContinueWith(innerTask =>
{
if (innerTask.IsFaulted)
{
tcs.SetException(innerTask.Exception.InnerExceptions);
}
else if (innerTask.IsCanceled)
{
tcs.SetCanceled();
}
else
{
tcs.SetResult(null);
}
}, TaskContinuationOptions.ExecuteSynchronously);
return(tcs.Task);
}