5 // Martin Baulig <martin.baulig@xamarin.com>
7 // Copyright (c) 2013 Xamarin Inc. (http://www.xamarin.com)
9 // Permission is hereby granted, free of charge, to any person obtaining a copy
10 // of this software and associated documentation files (the "Software"), to deal
11 // in the Software without restriction, including without limitation the rights
12 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
13 // copies of the Software, and to permit persons to whom the Software is
14 // furnished to do so, subject to the following conditions:
16 // The above copyright notice and this permission notice shall be included in
17 // all copies or substantial portions of the Software.
19 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
20 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
22 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
23 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
24 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
28 using System.Runtime.Serialization;
29 using System.Runtime.InteropServices;
32 [SerializableAttribute]
33 public sealed class WeakReference<T> : ISerializable
37 bool trackResurrection;
39 public WeakReference (T target)
40 : this (target, false)
44 public WeakReference (T target, bool trackResurrection)
46 this.trackResurrection = trackResurrection;
47 var handleType = trackResurrection ? GCHandleType.WeakTrackResurrection : GCHandleType.Weak;
48 handle = GCHandle.Alloc (target, handleType);
51 WeakReference (SerializationInfo info, StreamingContext context)
54 throw new ArgumentNullException ("info");
56 trackResurrection = info.GetBoolean ("TrackResurrection");
57 var target = info.GetValue ("TrackedObject", typeof (T));
59 var handleType = trackResurrection ? GCHandleType.WeakTrackResurrection : GCHandleType.Weak;
60 handle = GCHandle.Alloc (target, handleType);
63 public void GetObjectData (SerializationInfo info, StreamingContext context)
66 throw new ArgumentNullException ("info");
68 info.AddValue ("TrackResurrection", trackResurrection);
70 if (handle.IsAllocated)
71 info.AddValue ("TrackedObject", handle.Target);
73 info.AddValue ("TrackedObject", null);
76 public void SetTarget (T target)
78 handle.Target = target;
81 public bool TryGetTarget (out T target)
83 if (!handle.IsAllocated) {
88 target = (T)handle.Target;
89 return target != null;