OAVariantLib.cs

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using System;
using System.Globalization;
using System.Reflection;
using System.Runtime.CompilerServices;
 
namespace Microsoft.Win32;
 
internal static class OAVariantLib
{
    internal static readonly Type[] ClassTypes = new Type[23]
    {
        typeof(Empty),
        typeof(void),
        typeof(bool),
        typeof(char),
        typeof(sbyte),
        typeof(byte),
        typeof(short),
        typeof(ushort),
        typeof(int),
        typeof(uint),
        typeof(long),
        typeof(ulong),
        typeof(float),
        typeof(double),
        typeof(string),
        typeof(void),
        typeof(DateTime),
        typeof(TimeSpan),
        typeof(object),
        typeof(decimal),
        null,
        typeof(Missing),
        typeof(DBNull)
    };
 
    internal static Variant ChangeType(Variant source, Type targetClass, short options, CultureInfo culture)
    {
        if (targetClass == null)
        {
            throw new ArgumentNullException("targetClass");
        }
        if (culture == null)
        {
            throw new ArgumentNullException("culture");
        }
        Variant result = default(Variant);
        ChangeTypeEx(ref result, ref source, culture.LCID, targetClass.TypeHandle.Value, GetCVTypeFromClass(targetClass), options);
        return result;
    }
 
    private static int GetCVTypeFromClass(Type ctype)
    {
        int num = -1;
        for (int i = 0; i < ClassTypes.Length; i++)
        {
            if (ctype.Equals(ClassTypes[i]))
            {
                num = i;
                break;
            }
        }
        if (num == -1)
        {
            num = 18;
        }
        return num;
    }
 
    [MethodImpl(MethodImplOptions.InternalCall)]
    private static extern void ChangeTypeEx(ref Variant result, ref Variant source, int lcid, IntPtr typeHandle, int cvType, short flags);
}