GCHandle.cs :  » 2.6.4-mono-.net-core » System.Runtime » System » Runtime » InteropServices » C# / CSharp Open Source

//
// System.Runtime.InteropServices/GCHandle.cs
//
// Authors:
//   Ajay kumar Dwivedi (adwiv@yahoo.com) ??
//   Paolo Molaro (lupus@ximian.com)
//

//
// Copyright (C) 2004, 2009 Novell, Inc (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

using System;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;

namespace System.Runtime.InteropServices{

  [ComVisible(true)]
  [MonoTODO("Struct should be [StructLayout(LayoutKind.Sequential)] but will need to be reordered for that.")]
  public struct GCHandle 
  {
    // fields
    private int handle;

    private GCHandle(IntPtr h)
    {
      handle = (int)h;
    }
    
    // Constructors
    private GCHandle(object obj)
      : this(obj, GCHandleType.Normal)
    {}

    private GCHandle(object value, GCHandleType type)
    {
      // MS does not crash/throw on (most) invalid GCHandleType values (except -1)
      if ((type < GCHandleType.Weak) || (type > GCHandleType.Pinned))
        type = GCHandleType.Normal;
      handle = GetTargetHandle (value, 0, type);
    }

    // Properties

    public bool IsAllocated 
    { 
      get
      {
        return (handle != 0);
      }
    }

    public object Target
    { 
      get
      {
        if (!IsAllocated)
          throw new InvalidOperationException (Locale.GetText ("Handle is not allocated"));
        return GetTarget (handle);
      } 
      set
      {
        handle = GetTargetHandle (value, handle, (GCHandleType)(-1));
      } 
    }

    // Methods
    public IntPtr AddrOfPinnedObject()
    {
      IntPtr res = GetAddrOfPinnedObject(handle);
      if (res == (IntPtr)(-1))
        throw new ArgumentException ("Object contains non-primitive or non-blittable data.");
      if (res == (IntPtr)(-2))
        throw new InvalidOperationException("Handle is not pinned.");
      return res;
    }

    public static System.Runtime.InteropServices.GCHandle Alloc(object value)
    {
      return new GCHandle (value);
    }

    public static System.Runtime.InteropServices.GCHandle Alloc(object value, GCHandleType type)
    {
      return new GCHandle (value,type);
    }

    public void Free()
    {
      FreeHandle(handle);
      handle = 0;
    }
    
    public static explicit operator IntPtr (GCHandle value)
    {
      return (IntPtr) value.handle;
    }
    
    public static explicit operator GCHandle(IntPtr value)
    {
      if (value == IntPtr.Zero)
        throw new ArgumentException ("GCHandle value cannot be zero");
      if (!CheckCurrentDomain ((int)value))
        throw new ArgumentException ("GCHandle value belongs to a different domain");
      return new GCHandle (value);
    }

    [MethodImplAttribute(MethodImplOptions.InternalCall)]
    private extern static bool CheckCurrentDomain (int handle);
    
    [MethodImplAttribute(MethodImplOptions.InternalCall)]
    private extern static object GetTarget(int handle);

    [MethodImplAttribute(MethodImplOptions.InternalCall)]
    private extern static int GetTargetHandle(object obj, int handle, GCHandleType type);
    
    [MethodImplAttribute(MethodImplOptions.InternalCall)]
    private extern static void FreeHandle(int handle);
    
    [MethodImplAttribute(MethodImplOptions.InternalCall)]
    private extern static IntPtr GetAddrOfPinnedObject(int handle);

    public static bool operator ==(GCHandle a, GCHandle b)
    {
      return a.Equals(b);
    }

    public static bool operator !=(GCHandle a, GCHandle b)
    {
      return (!(a.Equals(b)));
    }
    
    public override bool Equals(object o)
    {
      if (o == null || !(o is GCHandle))
        return false;

      return (handle == ((GCHandle)o).handle);
    }

    public override int GetHashCode()
    {
      return handle.GetHashCode ();
    }

    public static GCHandle FromIntPtr (IntPtr value)
    {
      return (GCHandle)value;
    }

    public static IntPtr ToIntPtr (GCHandle value)
    {
      return (IntPtr)value;
    }
  } 
}