ParamsArray.cs

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namespace System;
 
internal readonly struct ParamsArray
{
    private static readonly object[] s_oneArgArray = new object[1];
 
    private static readonly object[] s_twoArgArray = new object[2];
 
    private static readonly object[] s_threeArgArray = new object[3];
 
    private readonly object _arg0;
 
    private readonly object _arg1;
 
    private readonly object _arg2;
 
    private readonly object[] _args;
 
    public int Length => _args.Length;
 
    public object this[int index]
    {
        get
        {
            if (index != 0)
            {
                return GetAtSlow(index);
            }
            return _arg0;
        }
    }
 
    public ParamsArray(object arg0)
    {
        _arg0 = arg0;
        _arg1 = null;
        _arg2 = null;
        _args = s_oneArgArray;
    }
 
    public ParamsArray(object arg0, object arg1)
    {
        _arg0 = arg0;
        _arg1 = arg1;
        _arg2 = null;
        _args = s_twoArgArray;
    }
 
    public ParamsArray(object arg0, object arg1, object arg2)
    {
        _arg0 = arg0;
        _arg1 = arg1;
        _arg2 = arg2;
        _args = s_threeArgArray;
    }
 
    public ParamsArray(object[] args)
    {
        int num = args.Length;
        _arg0 = ((num > 0) ? args[0] : null);
        _arg1 = ((num > 1) ? args[1] : null);
        _arg2 = ((num > 2) ? args[2] : null);
        _args = args;
    }
 
    private object GetAtSlow(int index)
    {
        return index switch
        {
            1 => _arg1, 
            2 => _arg2, 
            _ => _args[index], 
        };
    }
}