CollectionHelpers.cs

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using System.Collections.Generic;
 
namespace System.Collections;
 
internal static class CollectionHelpers
{
    internal static void ValidateCopyToArguments(int sourceCount, Array array, int index)
    {
        if (array == null)
        {
            throw new ArgumentNullException("array");
        }
        if (array.Rank != 1)
        {
            throw new ArgumentException(System.SR.Arg_RankMultiDimNotSupported, "array");
        }
        if (array.GetLowerBound(0) != 0)
        {
            throw new ArgumentException(System.SR.Arg_NonZeroLowerBound, "array");
        }
        if (index < 0 || index > array.Length)
        {
            throw new ArgumentOutOfRangeException("index", System.SR.ArgumentOutOfRange_NeedNonNegNum);
        }
        if (array.Length - index < sourceCount)
        {
            throw new ArgumentException(System.SR.Arg_ArrayPlusOffTooSmall);
        }
    }
 
    internal static void CopyTo<T>(ICollection<T> collection, Array array, int index)
    {
        ValidateCopyToArguments(collection.Count, array, index);
        if (collection is ICollection collection2)
        {
            collection2.CopyTo(array, index);
            return;
        }
        if (array is T[] array2)
        {
            collection.CopyTo(array2, index);
            return;
        }
        if (!(array is object[] array3))
        {
            throw new ArgumentException(System.SR.Argument_InvalidArrayType, "array");
        }
        try
        {
            foreach (T item in collection)
            {
                array3[index++] = item;
            }
        }
        catch (ArrayTypeMismatchException)
        {
            throw new ArgumentException(System.SR.Argument_InvalidArrayType, "array");
        }
    }
}