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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
// This class represents the Ole Automation binder.
// #define DISPLAY_DEBUG_INFO
namespace System {
using System;
using System.Runtime.InteropServices;
using System.Reflection;
using Microsoft.Win32;
using CultureInfo = System.Globalization.CultureInfo;
// Made serializable in anticipation of this class eventually having state.
[Serializable]
internal class OleAutBinder : DefaultBinder
{
// ChangeType
// This binder uses OLEAUT to change the type of the variant.
[System.Security.SecuritySafeCritical] // overrides transparent member
public override Object ChangeType(Object value, Type type, CultureInfo cultureInfo)
{
Variant myValue = new Variant(value);
if (cultureInfo == null)
cultureInfo = CultureInfo.CurrentCulture;
#if DISPLAY_DEBUG_INFO
Console.WriteLine("In OleAutBinder::ChangeType converting variant of type: {0} to type: {1}", myValue.VariantType, type.Name);
#endif
if (type.IsByRef)
{
#if DISPLAY_DEBUG_INFO
Console.WriteLine("Stripping byref from the type to convert to.");
#endif
type = type.GetElementType();
}
// If we are trying to convert from an object to another type then we don't
// need the OLEAUT change type, we can just use the normal COM+ mechanisms.
if (!type.IsPrimitive && type.IsInstanceOfType(value))
{
#if DISPLAY_DEBUG_INFO
Console.WriteLine("Source variant can be assigned to destination type");
#endif
return value;
}
Type srcType = value.GetType();
// Handle converting primitives to enums.
if (type.IsEnum && srcType.IsPrimitive)
{
#if DISPLAY_DEBUG_INFO
Console.WriteLine("Converting primitive to enum");
#endif
return Enum.Parse(type, value.ToString());
}
#if !FEATURE_CORECLR
// Special case the convertion from DBNull.
if (srcType == typeof(DBNull))
{
// The requested type is a DBNull so no convertion is required.
if (type == typeof(DBNull))
return value;
// Visual J++ supported converting from DBNull to null so customers
// have requested (via a CDCR) that DBNull be convertible to null.
// We don't however allow this when converting to a value class, since null
// doesn't make sense for these, or to object since this would change existing
// semantics.
if ((type.IsClass && type != typeof(Object)) || type.IsInterface)
return null;
}
#endif //!FEATURE_CORECLR
// Use the OA variant lib to convert primitive types.
try
{
#if DISPLAY_DEBUG_INFO
Console.WriteLine("Using OAVariantLib.ChangeType() to do the conversion");
#endif
// Specify the LocalBool flag to have BOOL values converted to local language rather
// than 0 or -1.
Object RetObj = OAVariantLib.ChangeType(myValue, type, OAVariantLib.LocalBool, cultureInfo).ToObject();
#if DISPLAY_DEBUG_INFO
Console.WriteLine("Object returned from ChangeType is of type: " + RetObj.GetType().Name);
#endif
return RetObj;
}
#if DISPLAY_DEBUG_INFO
catch(NotSupportedException e)
#else
catch(NotSupportedException)
#endif
{
#if DISPLAY_DEBUG_INFO
Console.Write("Exception thrown: ");
Console.WriteLine(e);
#endif
throw new COMException(Environment.GetResourceString("Interop.COM_TypeMismatch"), unchecked((int)0x80020005));
}
}
}
}
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