mcs/class/System.Core/System.Threading.Tasks/TaskExtensions.cs

   1 //
   2 // TaskExtensions.cs
   3 //
   4 // Author:
   5 //       Jérémie "Garuma" Laval <jeremie.laval@gmail.com>
   6 //
   7 // Copyright (c) 2010 Jérémie "Garuma" Laval
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining
  10 // a copy of this software and associated documentation files (the
  11 // "Software"), to deal in the Software without restriction, including
  12 // without limitation the rights to use, copy, modify, merge, publish,
  13 // distribute, sublicense, and/or sell copies of the Software, and to
  14 // permit persons to whom the Software is furnished to do so, subject to
  15 // the following conditions:
  16 //
  17 // The above copyright notice and this permission notice shall be
  18 // included in all copies or substantial portions of the Software.
  19 //
  20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27 //
  28
  29 #if NET_4_0 || MOBILE
  30
  31 using System;
  32 using System.Threading.Tasks;
  33
  34 namespace System.Threading.Tasks
  35 {
  36         public static class TaskExtensions
  37         {
  38                 const TaskContinuationOptions opt = TaskContinuationOptions.ExecuteSynchronously;
  39
  40                 public static Task<TResult> Unwrap<TResult> (this Task<Task<TResult>> task)
  41                 {
  42                         if (task == null)
  43                                 throw new ArgumentNullException ("task");
  44
  45                         TaskCompletionSource<TResult> src = new TaskCompletionSource<TResult> ();
  46
  47                         task.ContinueWith (t1 => CopyCat (t1, src, () => t1.Result.ContinueWith (t2 => CopyCat (t2, src, () => src.SetResult (t2.Result)), opt)), opt);
  48
  49                         return src.Task;
  50                 }
  51
  52                 public static Task Unwrap (this Task<Task> task)
  53                 {
  54                         if (task == null)
  55                                 throw new ArgumentNullException ("task");
  56
  57                         TaskCompletionSource<object> src = new TaskCompletionSource<object> ();
  58
  59                         task.ContinueWith (t1 => CopyCat (t1, src, () => t1.Result.ContinueWith (t2 => CopyCat (t2, src, () => src.SetResult (null)), opt)), opt);
  60
  61                         return src.Task;
  62                 }
  63
  64                 static void CopyCat<TResult> (Task source,
  65                                               TaskCompletionSource<TResult> dest,
  66                                               Action normalAction)
  67                 {
  68                         if (source.IsCanceled)
  69                                 dest.SetCanceled ();
  70                         else if (source.IsFaulted)
  71                                 dest.SetException (source.Exception.InnerExceptions);
  72                         else
  73                                 normalAction ();
  74                 }
  75         }
  76 }
  77
  78 #endif