mcs/class/corlib/System.Runtime.InteropServices/GCHandle.cs

   1 //
   2 // System.Runtime.InteropServices/GCHandle.cs
   3 //
   4 // Authors:
   5 //   Ajay kumar Dwivedi (adwiv@yahoo.com) ??
   6 //   Paolo Molaro (lupus@ximian.com)
   7 //
   8
   9 //
  10 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  11 //
  12 // Permission is hereby granted, free of charge, to any person obtaining
  13 // a copy of this software and associated documentation files (the
  14 // "Software"), to deal in the Software without restriction, including
  15 // without limitation the rights to use, copy, modify, merge, publish,
  16 // distribute, sublicense, and/or sell copies of the Software, and to
  17 // permit persons to whom the Software is furnished to do so, subject to
  18 // the following conditions:
  19 //
  20 // The above copyright notice and this permission notice shall be
  21 // included in all copies or substantial portions of the Software.
  22 //
  23 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  27 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  28 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  29 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  30 //
  31
  32 using System;
  33 using System.Runtime.CompilerServices;
  34 using System.Runtime.InteropServices;
  35
  36 namespace System.Runtime.InteropServices
  37 {
  38         /// <summary>
  39         /// Summary description for GCHandle.
  40         /// </summary>
  41         public struct GCHandle
  42         {
  43                 // fields
  44                 private int handle;
  45
  46                 private GCHandle(IntPtr h)
  47                 {
  48                         handle = (int)h;
  49                 }
  50
  51                 // Constructors
  52                 private GCHandle(object obj)
  53                         : this(obj, GCHandleType.Normal)
  54                 {}
  55
  56                 private GCHandle(object value, GCHandleType type)
  57                 {
  58                         handle = GetTargetHandle (value, 0, type);
  59                 }
  60
  61                 // Properties
  62
  63                 public bool IsAllocated
  64                 {
  65                         get
  66                         {
  67                                 return (handle != 0);
  68                         }
  69                 }
  70
  71                 public object Target
  72                 {
  73                         get
  74                         {
  75                                 return GetTarget (handle);
  76                         }
  77                         set
  78                         {
  79                                 handle = GetTargetHandle (value, handle, (GCHandleType)(-1));
  80                         }
  81                 }
  82
  83                 // Methods
  84                 public IntPtr AddrOfPinnedObject()
  85                 {
  86                         IntPtr res = GetAddrOfPinnedObject(handle);
  87                         if (res == IntPtr.Zero)
  88                                 throw new InvalidOperationException("The handle is not of Pinned type");
  89                         return res;
  90                 }
  91
  92                 public static System.Runtime.InteropServices.GCHandle Alloc(object value)
  93                 {
  94                         return new GCHandle (value);
  95                 }
  96
  97                 public static System.Runtime.InteropServices.GCHandle Alloc(object value, GCHandleType type)
  98                 {
  99                         return new GCHandle (value,type);
 100                 }
 101
 102                 public void Free()
 103                 {
 104                         FreeHandle(handle);
 105                         handle = 0;
 106                 }
 107
 108                 public static explicit operator IntPtr (GCHandle value)
 109                 {
 110                         return (IntPtr) value.handle;
 111                 }
 112
 113                 public static explicit operator GCHandle(IntPtr value)
 114                 {
 115                         return new GCHandle (value);
 116                 }
 117
 118                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
 119                 private extern static object GetTarget(int handle);
 120
 121                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
 122                 private extern static int GetTargetHandle(object obj, int handle, GCHandleType type);
 123
 124                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
 125                 private extern static void FreeHandle(int handle);
 126
 127                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
 128                 private extern static IntPtr GetAddrOfPinnedObject(int handle);
 129         }
 130 }
 131