EnumVariantViewOfEnumerator.cs

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using System.Collections;
using System.Runtime.InteropServices.ComTypes;
 
namespace System.Runtime.InteropServices.CustomMarshalers;
 
internal sealed class EnumVariantViewOfEnumerator : IEnumVARIANT, ICustomAdapter
{
    public System.Collections.IEnumerator Enumerator { get; }
 
    public EnumVariantViewOfEnumerator(System.Collections.IEnumerator enumerator)
    {
        if (enumerator == null)
        {
            throw new ArgumentNullException("enumerator");
        }
        Enumerator = enumerator;
    }
 
    public IEnumVARIANT Clone()
    {
        if (Enumerator is ICloneable cloneable)
        {
            return new EnumVariantViewOfEnumerator((System.Collections.IEnumerator)cloneable.Clone());
        }
        throw new COMException(SR.Arg_EnumNotCloneable, -2147467259);
    }
 
    public int Next(int celt, object[] rgVar, IntPtr pceltFetched)
    {
        int num = 0;
        try
        {
            if (celt > 0 && rgVar == null)
            {
                return -2147024809;
            }
            while (num < celt && Enumerator.MoveNext())
            {
                rgVar[num++] = Enumerator.Current;
            }
            if (pceltFetched != IntPtr.Zero)
            {
                Marshal.WriteInt32(pceltFetched, num);
            }
        }
        catch (Exception ex)
        {
            return ex.HResult;
        }
        if (num != celt)
        {
            return 1;
        }
        return 0;
    }
 
    public int Reset()
    {
        try
        {
            Enumerator.Reset();
        }
        catch (Exception ex)
        {
            return ex.HResult;
        }
        return 0;
    }
 
    public int Skip(int celt)
    {
        try
        {
            while (celt > 0 && Enumerator.MoveNext())
            {
                celt--;
            }
        }
        catch (Exception ex)
        {
            return ex.HResult;
        }
        if (celt != 0)
        {
            return 1;
        }
        return 0;
    }
 
    public object GetUnderlyingObject()
    {
        return Enumerator;
    }
}